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Sample records for methyl bromide exposure

  1. Uptake and excretion of ( UC)methyl bromide as influenced by exposure concentration

    SciTech Connect

    Medinsky, M.A.; Dutcher, J.S.; Bond, J.A.; Henderson, R.F.; Mauderly, J.L.; Snipes, M.B.; Mewhinney, J.A.; Cheng, Y.S.; Birnbaum, L.S.

    1985-01-01

    Uptake of methyl bromide and pathways for excretion of UC were investigated in male Fischer-344 rats after nose-only inhalation of 50, 300, 5700, or 10,400 nmol (1.6 to 310 ppm) of ( UC)methyl bromide/liter of air for 6 hr. Fractional uptake of methyl bromide decreased at the highest concentrations, 5700 and 10,400 nmol/liter, with 37 and 27% of the inhaled methyl bromide absorbed, respectively, compared to 48% at the lower levels. Total methyl bromide absorbed was 9 or 40 mol/kg body wt after exposure to 50 or 300 nmol/liter, respectively. Elimination of UC was linearly related to the amount of methyl bromide absorbed as determined from urine, feces, expired CO2, and parent compound collected for 66 hr after the end of exposure. Exhaled UCO2 was the dominant route of excretion, with from 1.2 to 110 mol (50% of amount absorbed) exhaled, and was described by a two-component negative exponential function; 85% was exhaled with t1/2 of 4 hr, and the remaining 15% was exhaled with a t1/2 of 17 hr. The rate of exhalation of UCO2 was not affected by the amount of ( UC)methyl bromide absorbed. From 0.4 to 54 mol was excreted in urine (20% of amount absorbed). The half-time for excretion of UC in urine was approximately 10 hr, and the rate of excretion was not dependent on the amount of ( UC)methyl bromide absorbed. Little UC was exhaled as methyl bromide (<4% of the dose) or excreted in feces (<2%). At the end of 66 hr, 25% of the UC absorbed remained in the rats. Liver, kidneys, adrenals, lungs, thymus, and turbinates (maxilloturbinates, ethmoturbinates, and nasal epithelial membrane) contained the highest concentrations of UC. Results indicated that uptake of inhaled methyl bromide could be saturated. Any ( UC)methyl bromide equivalents absorbed, however, would be excreted by concentration-independent mechanisms. 20 references, 5 figures, 4 tables.

  2. Severe Illness from Methyl Bromide Exposure at a Condominium Resort--U.S. Virgin Islands, March 2015.

    PubMed

    Kulkarni, Prathit A; Duncan, Mary Anne; Watters, Michelle T; Graziano, Leah T; Vaouli, Elena; Cseh, Larry F; Risher, John F; Orr, Maureen F; Hunte-Ceasar, Tai C; Ellis, Esther M

    2015-07-24

    On March 22, 2015, the Agency for Toxic Substances and Disease Registry (ATSDR) was notified by the U.S. Environmental Protection Agency (EPA) of four cases of suspected acute methyl bromide toxicity among family members vacationing at a condominium resort in the U.S. Virgin Islands. Methyl bromide is a pesticide that has been banned in the United States for use in homes and other residential settings. An investigation conducted by the U.S. Virgin Islands Department of Health (VIDOH), the U.S. Virgin Islands Department of Planning and Natural Resources (DPNR), and EPA confirmed that methyl bromide had been used as a fumigant on March 18 in the building where the family had been residing, 2 days before they were transported to the hospital; three family members had life-threatening illness. On March 25, 2015, a stop-use order for methyl bromide was issued by DPNR to the pest control company that had performed the fumigation. Subsequent investigation revealed that previous fumigation with methyl bromide had occurred on October 20, 2014, at the same condominium resort. In addition to the four ill family members, 37 persons who might have been exposed to methyl bromide as a result of the October 2014 or March 2015 fumigations were identified by VIDOH and ATSDR. Standardized health questionnaires were administered to 16 of the 20 persons for whom contact information was available; six of 16 had symptoms consistent with methyl bromide exposure, including headache and fatigue. Pest control companies should be aware that use of methyl bromide is banned in homes and other residential settings, and clinicians should be aware of the toxicologic syndrome that exposure to methyl bromide can cause.

  3. Post-exposure treatment with nasal atropine methyl bromide protects against microinstillation inhalation exposure to sarin in guinea pigs

    SciTech Connect

    Che, Magnus M.; Conti, Michele; Boylan, Megan; Sabnekar, Praveena; Rezk, Peter; Sciuto, Alfred M.; Doctor, Bhupendra P.; Nambiar, Madhusoodana P.

    2009-09-15

    We evaluated the protective efficacy of nasal atropine methyl bromide (AMB) which does not cross the blood-brain barrier against sarin inhalation exposure. Age and weight matched male guinea pigs were exposed to 846.5 mg/m{sup 3} sarin using a microinstillation inhalation exposure technique for 4 min. The survival rate at this dose was 20%. Post-exposure treatment with nasal AMB (2.5 mg/kg, 1 min) completely protected against sarin induced toxicity (100% survival). Development of muscular tremors was decreased in animals treated with nasal AMB. Post-exposure treatment with nasal AMB also normalized acute decrease in blood oxygen saturation and heart rate following sarin exposure. Inhibition of blood AChE and BChE activities following sarin exposure was reduced in animals treated with nasal AMB, indicating that survival increases the metabolism of sarin or expression of AChE. The body weight loss of animals exposed to sarin and treated with nasal AMB was similar to saline controls. No differences were observed in lung accessory lobe or tracheal edema following exposure to sarin and subsequent treatment with nasal AMB. Total bronchoalveolar lavage fluid (BALF) protein, a biomarker of lung injury, showed trends similar to saline controls. Surfactant levels post-exposure treatment with nasal AMB returned to normal, similar to saline controls. Alkaline phosphatase levels post-exposure treatment with nasal AMB were decreased. Taken together, these data suggest that nasal AMB blocks the copious airway secretion and peripheral cholinergic effects and protects against lethal inhalation exposure to sarin thus increasing survival.

  4. Post-exposure treatment with nasal atropine methyl bromide protects against microinstillation inhalation exposure to sarin in guinea pigs.

    PubMed

    Che, Magnus M; Conti, Michele; Chanda, Soma; Boylan, Megan; Sabnekar, Praveena; Rezk, Peter; Amari, Ethery; Sciuto, Alfred M; Gordon, Richard K; Doctor, Bhupendra P; Nambiar, Madhusoodana P

    2009-09-15

    We evaluated the protective efficacy of nasal atropine methyl bromide (AMB) which does not cross the blood-brain barrier against sarin inhalation exposure. Age and weight matched male guinea pigs were exposed to 846.5 mg/m(3) sarin using a microinstillation inhalation exposure technique for 4 min. The survival rate at this dose was 20%. Post-exposure treatment with nasal AMB (2.5 mg/kg, 1 min) completely protected against sarin induced toxicity (100% survival). Development of muscular tremors was decreased in animals treated with nasal AMB. Post-exposure treatment with nasal AMB also normalized acute decrease in blood oxygen saturation and heart rate following sarin exposure. Inhibition of blood AChE and BChE activities following sarin exposure was reduced in animals treated with nasal AMB, indicating that survival increases the metabolism of sarin or expression of AChE. The body weight loss of animals exposed to sarin and treated with nasal AMB was similar to saline controls. No differences were observed in lung accessory lobe or tracheal edema following exposure to sarin and subsequent treatment with nasal AMB. Total bronchoalveolar lavage fluid (BALF) protein, a biomarker of lung injury, showed trends similar to saline controls. Surfactant levels post-exposure treatment with nasal AMB returned to normal, similar to saline controls. Alkaline phosphatase levels post-exposure treatment with nasal AMB were decreased. Taken together, these data suggest that nasal AMB blocks the copious airway secretion and peripheral cholinergic effects and protects against lethal inhalation exposure to sarin thus increasing survival.

  5. An Ill Wind: Methyl Bromide Use Near California Schools, 1998.

    ERIC Educational Resources Information Center

    Ross, Zev; Walker, Bill

    A California study investigates the use of the toxic pesticide methyl bromide near the state's public schools, explains why proposed safety rules have failed to protect children and others from exposure, and examines regions at particular exposure risk. Study results show an increasing exposure to methyl bromide near schools already at risk while…

  6. Methyl bromide users search for science

    SciTech Connect

    Winegar, E.D.

    1995-01-01

    Workers, neighbors and the ozone are protected by regulation from this chemical, but those needing it complain that a solid foundation is lacking for the rules. Although not yet featured on {open_quotes}60 Minutes,{close_quotes} the pesticide methyl bromide is gaining widespread attention because of its central position in debates about worker health and safety, environmental toxics exposure and global ozone depletion.

  7. A new methyl bromide gas generator for inhalation toxicity studies.

    PubMed

    Hori, H; Hyakudo, T; Tanaka, I

    1992-09-01

    A simple generator for methyl bromide gas has been newly developed by us. For inhalation toxicity studies, until now, there have been few generators capable of producing a constant and stable concentration of methyl bromide gas easily because of its high volatility. The principle of this new generator is based on gas-liquid equilibrium. The gas is generated from the surface of liquid methyl bromide in an evaporator made of a Teflon tube. The generator can produce up to 10,000 ppm of methyl bromide gas in a 0.1 m3 exposure chamber, and the concentration of this generated gas is able to be kept within +/- 0.8% over a long period of time. The generator has proved to be useful for investigating the effects of methyl bromide on health in inhalation toxicity studies.

  8. Degeneration and regeneration of the olfactory epithelium following inhalation exposure to methyl bromide: pathology, cell kinetics, and olfactory function.

    PubMed

    Hurtt, M E; Thomas, D A; Working, P K; Monticello, T M; Morgan, K T

    1988-06-30

    The effects of acute inhalation exposure to methyl bromide (MeBr) on the olfactory epithelium of male F-344 rats was investigated by morphologic examination of animals killed at varying timepoints during and following exposure to 200 ppm MeBr 6 hr/day for 5 days. Cell replication rate and histopathology were used to assess the kinetics of repair. In addition, olfactory function, using the buried food pellet test, was assessed and the result compared with morphological recovery. Extensive destruction of the olfactory epithelium was evident in animals killed directly after a single 6-hr exposure to MeBr. Histologic features of these lesions indicate that the primary, or most severe, effect of MeBr exposure was on the sustentacular cells and mature sensory cells; basal cells were generally unaffected. By Day 3, despite continued exposure, there was replacement of the olfactory epithelium by a squamous cell layer that increased in thickness and basophilic cytoplasmic staining over the next 2 days of exposure. One week postexposure, the epithelial region was covered by a layer of polyhedral, basophilic cells, and from 2 to 10 weeks postexposure, the epithelium exhibited progressive reorganization to reform the original olfactory epithelium pattern. By Week 10, 75-80% of the olfactory epithelium appeared morphologically normal. Cell replication showed a single peak of olfactory epithelial cell proliferation at Day 3 of exposure, with a labeling index of 14.5% compared to 0.7% in controls. Cell replication rates returned gradually to control levels by Week 10 postexposure. Behavioral tests of olfactory function in animals after a single 6-hr exposure to 200 ppm MeBr demonstrated a loss of the sense of smell, with recovery of this function by Day 6. Exposure to 90 ppm caused no observable effect on olfactory function or morphology. These findings demonstrate that the olfactory mucosa is highly sensitive to the toxic effects of MeBr and that olfactory epithelial cell

  9. Measuring methyl bromide emissions from fields

    SciTech Connect

    Yates, S.R.; Gan, J.; Ernst, F.F.; Yates, M.V.

    1995-12-31

    Methyl bromide is used extensively for pest control. Recent evidence suggests that methyl bromide may react with stratospheric ozone and, due to the Clean Air Act, is scheduled for phase-out within the next 5 to 10 years. As indicated in a recent report from The National Agricultural Pesticide Impact Assessment Program, there will be substantial economic impact on the agricultural community if the use of methyl bromide is restricted. There are several areas of uncertainty concerning the agricultural use of methyl bromide. Foremost is the quantification of mass emitted to the atmosphere from agricultural fields. To address this, two field experiments were conducted to directly measure methyl bromide emissions. In the first experiment, methyl bromide was injected at approximately 25 cm depth and the soil was covered with 1 mil high-density polyethylene plastic. The second experiment was similar except that methyl bromide was injected at approximately 68 cm depth and the soil was not covered. From these experiments, the emission rate into the atmosphere and the subsurface transport of methyl bromide was determined. Both experiments include a field-scale mass balance to verify the accuracy of the flux-measurement methods as well as to check data consistency. The volatilization rate and mass lost was determined from estimates of the degradation and from several atmospheric and chamber flux methods.

  10. Health and Environmental Effects Profile for methyl bromide

    SciTech Connect

    Not Available

    1986-06-01

    The Health and Environmental Effects Profile for methyl bromide was prepared to support listings of hazardous constituents of a wide range of waste streams under Section 3001 of the Resource Conservation and Recovery Act (RCRA) and to provide health-related limits for emergency actions under Section 101 of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). Both published literature and information obtained from Agency program office files were evaluated as they pertained to potential human health, aquatic life, and environmental effects. Quantitative estimates are presented provided sufficient data are available. Methyl bromide has been determined to be a systemic toxicant. An Acceptable Daily Intake (ADI), for methyl bromide is 0.0014 mg/kg/day for oral exposure. The Reportable Quantity (RQ) value for methyl bromide is 100.

  11. Disposition of ( UC)methyl bromide in rats after inhalation

    SciTech Connect

    Bond, J.A.; Dutcher, J.S.; Medinsky, M.A.; Henderson, R.F.; Birnbaum, L.S.

    1985-01-01

    The purpose of this investigation was to determine the disposition and metabolism of ( UC)methyl bromide in rats after inhalation. Male Fischer-344 rats were exposed nose only to a vapor concentration of 337 nmol ( UC)methyl bromide/liter air (9.0 ppm, 25C, 620 torr) for 6 hr. Urine, feces, expired air, and tissues were collected for up to 65 hr after exposure. Elimination of UC as UCO2 was the major route of excretion with about 47% (3900 nmol/rat) of the total ( UC)methyl bromide absorbed excreted by this route. CO2 excretion exhibited a biphasic elimination pattern with 85% of the UCO2 being excreted with a half-time of 3.9 +/- 0.1 hr (anti x +/- SE) and 15% excreted with a half-time of 11.4 +/- 0.2 hr. Half-times for elimination of UC in urine and feces were 9.6 +/- 0.1 and 16.1 +/- 0.1 hr, respectively. By 65 hr after exposure, about 75% of the initial radioactivity had been excreted with 25% remaining in the body. Radioactivity was widely distributed in tissues immediately following exposure with lung (250 nmol equivalents/g), adrenal (240 nmol equivalents/g), and nasal turbinates (110 nmol equivalents/g) containing the highest concentrations of UC. Radioactivity in livers immediately after exposure accounted for about 17% of the absorbed methyl bromide. Radioactivity in all other tissues examined accounted for about 10% of the absorbed methyl bromide. Elimination half-times of UC from tissues were on the order of 1.5 to 8 hr. In all tissues examined, over 90% of the UC in the tissues was methyl bromide metabolities. The data from this study indicate that after inhalation methyl bromide is rapidly metabolized in tissues and readily excreted. 22 references, 4 figures, 4 tables.

  12. Emission of methyl bromide from biomass burning

    SciTech Connect

    Manoe, S.; Andreae, M.O. )

    1994-03-04

    Bromine is, per atom, far more efficient than chlorine in destroying stratospheric ozone, and methyl bromide is the single largest source of stratospheric bromine. The two main previously known sources of this compound are emissions from the ocean and from the compound's use as an agricultural pesticide. Laboratory biomass combustion experiments showed that methyl bromide was emitted in the smoke from various fuels tested. Methyl bromide was also found in smoke plumes from wildfires in savannas, chaparral, and boreal forest. Global emissions of methyl bromide from biomass burning are estimated to be in the range of 10 to 50 gigagrams per year, which is comparable to the amount produced by ocean emission and pesticide use and represents a major contribution ([approximately]30 percent) to the stratospheric bromine budget.

  13. Methyl bromide as a microbicidal fumigant for tree nuts.

    PubMed Central

    Schade, J E; King, A D

    1977-01-01

    Methyl bromide (MeBr) has broad microbicidal activity, but its use as a disinfectant for food is limited by the resulting bromide residues. Increasing the MeBr concentration, exposure temperature, or exposure period of a treatment tended to increase both the microbicidal efficacy of MeBr and the bromide residues. Its sporicidal activity was less at high than at low relative humidity within the range of 20 to 99%. Both the efficacy and the resulting residues of a MeBr treatment varied inversely with the load of product in a fumigation chamber due to sorption of the fumigant. Fumigation tests with almond kernels inoculated with Escherichia coli or Salmonella typhimurium indicated that MeBr can be used to disinfect whole nut kernels without resulting in excessive bromide residues, although the MeBr level necessary is higher than that normally used for insect control. PMID:406844

  14. 77 FR 35295 - Methyl Bromide; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-13

    .... Background In the Federal Register of April 6, 2012 (77 FR 20752) (FRL-9345- 1), EPA issued a proposed rule... methyl bromide in or on cotton, undelinted seed under the Federal Food, Drug, and Cosmetic Act (FFDCA... on cotton, undelinted seed at 150 parts per million (ppm). EPA issued a proposed rule that...

  15. Can Georgia growers replace methyl bromide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The price and availability of methyl bromide is limiting its use on Georgia farms; the need for an alternative is essential for sustainable vegetable production in GA. Three alternatives were evaluated in on-farm trials in the spring 2007 in Tift, Colquitt and Echols Counties. Treatments were replic...

  16. 40 CFR 180.124 - Methyl bromide; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Methyl bromide; tolerances for... § 180.124 Methyl bromide; tolerances for residues. (a) General. A tolerance is established for residues of the fumigant methyl bromide, including metabolites and degradates, in or on the commodity in...

  17. Methyl bromide fumigation of packed table grapes: Effect of shipping box on gas concentrations and phytotoxicity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Current methyl bromide schedules for table grapes to control mealybugs are approved for fruit packed in Toyon Kraft Veneer (TKV) boxes. The question arose concerning equivalence of exposure to methyl bromide if an Extruded Polystyrene (EPS) box was used in lieu of the TKV box for table grapes being ...

  18. Measurements of atmospheric methyl bromide and bromoform

    SciTech Connect

    Cicerone, R.J.; Heidt, L.E.; Pollock, W.H.

    1988-04-20

    We have measured gaseous methyl bromide (CH/sub 3/Br) and bromoform (CHBr/sub 3/) in air samples that were gathered approximately weekly from five ground-level sites: Point Barrow, Alaska; Mauna Loa Observatory and Cape Kumukahi, Hawaii; Matatula, Samoa; and Kaitorete Spit, New Zealand. Approximately 750 samples have been analyzed for CH/sub 3/Br between January 1985 and October 1987 and 990 samples have been analyzed for CHBr/sub 3/ between early 1984 and September 1987, all by gas chromatography/mass spectroscopy. Methyl bromide concentrations are typically 10--11 parts per trillion (ppt) by volume; there are no clear indications of temporal increases. Bromoform concentrations are typically 2--3 ppt, but large seasonal variations are seen at Point Barrow. copyright American Geophysical Union 1988

  19. [Research advances in methyl bromide in the ocean].

    PubMed

    Du, Hui-na; Xie, Wen-xia; Cui, Yu-qian; Chen, Jian-lei; Ye, Si-yuan

    2014-12-01

    Methyl bromide is an important atmospheric trace gas, which plays significant roles in the global warming and atmospheric chemistry. The ocean plays important and complex roles in the global biogeochemical cycles of methyl bromide, not only the source of atmospheric methyl bromide, but also the sink. Therefore, developing the chemical research of the soluble methyl bromide in the ocean, will not only have a certain guiding significance to the atmospheric ozone layer protection, but also provide a theoretical basis for estimating methyl bromide's contribution to the global environmental change on global scale. This paper reviewed the research advances on methyl bromide in the ocean, from the aspects of the biogeochemical cycle of methyl bromide in the ocean, the analysis and determination method, the concentration distribution, the sea-to-air flux and its sources and sinks in the atmosphere. Some deficiencies in the current studies were put forward, and the directions of the future studies were prospected. PMID:25876424

  20. [Research advances in methyl bromide in the ocean].

    PubMed

    Du, Hui-na; Xie, Wen-xia; Cui, Yu-qian; Chen, Jian-lei; Ye, Si-yuan

    2014-12-01

    Methyl bromide is an important atmospheric trace gas, which plays significant roles in the global warming and atmospheric chemistry. The ocean plays important and complex roles in the global biogeochemical cycles of methyl bromide, not only the source of atmospheric methyl bromide, but also the sink. Therefore, developing the chemical research of the soluble methyl bromide in the ocean, will not only have a certain guiding significance to the atmospheric ozone layer protection, but also provide a theoretical basis for estimating methyl bromide's contribution to the global environmental change on global scale. This paper reviewed the research advances on methyl bromide in the ocean, from the aspects of the biogeochemical cycle of methyl bromide in the ocean, the analysis and determination method, the concentration distribution, the sea-to-air flux and its sources and sinks in the atmosphere. Some deficiencies in the current studies were put forward, and the directions of the future studies were prospected.

  1. Methyl bromide: Ocean sources, ocean sinks, and climate sensitivity

    SciTech Connect

    Anbar, A.D.; Yung, Y.L.; Chavez, F.P.

    1996-03-01

    This study was performed to examine conflicting conclusions of two previously published studies which estimated the size of oceanic sources of methyl bromide. In addition, the sensitivity of atmospheric methyl bromide to climatic variations was examined. A steady state mass balance model was used to reexamine data from the previous studies. Linear scaling of methyl bromide production rates to chlorophyll content provided agreement between the two models. The results suggest that the open ocean is a small net sink for atmospheric methyl bromide, rather than a large net source. A high rate of biological production of methyl bromide in seawater is also strongly indicated. A coupled ocean-atmosphere model indicated that methyl bromide variations induced by climatic change can be larger than those resulting from 25% variations in anthropogenic sources. Quantifying marine production rates of methyl bromide is suggested as a necessary step in assessing stratospheric ozone loss. 63 refs., 10 figs., 2 tabs.

  2. Methyl bromide volatility measurements from treated fields

    SciTech Connect

    Majewski, M.S.; Woodrow, J.E.; Seiber, J.N. |

    1995-12-31

    Methyl bromide is used as an agricultural soil fumigant and concern is growing over the role it may play in the depletion of stratospheric ozone. Methyl bromide is applied using various techniques and little is known about how much of the applied fumigant volatilizes into the atmosphere after application. The post-application volatilization losses of methyl bromide from two fields using different application practices were measured using an aerodynamic-gradient technique. One field was covered with a high-barrier plastic film tarp during application and the other was left uncovered, but the furrows made by the injection shanks were bedded over. The cumulative volatilization losses from the tarped field were 22% of the nominal application within the first 5 days of the experiment and about 32% of the nominal application within 9 days including the one day after the tarp was removed on day 8. The nontarped field lost 89%of the nominal application by volatilization in 5 days. The error associated, with each flux measurement, as well as variations in daily flux losses with differing sampling period lengths show the degree of variability inherent in this type of study.

  3. Degradation of methyl bromide in anaerobic sediments

    USGS Publications Warehouse

    Oremland, R.S.; Miller, L.G.; Strohmaler, F.E.

    1994-01-01

    Methyl bromide (MeBr) was anaerobically degraded in saltmarsh sediments after reaction with sulfide. The product of this nucleophilic substitution reaction was methanethiol, which underwent further chemical and bacterial reactions to form dimethyl sulfide. These two gases appeared transiently during sediment incubations because they were metabolized by methanogenic and sulfate-reducing bacteria. A second, less significant reaction of MeBr was the exchange with chloride, forming methyl chloride, which was also susceptible to attack by sulfide. Incubation of 14C-labeled methyl iodide as an analogue of MeBr resulted in the formation of 14CH4 and 14CO2 and also indicated that sulfate-reducing bacteria as well as methanogens metabolized the methylated sulfur intermediates. These results suggest that exposed sediments with abundant free sulfide, such as coastal salt-marshes, may constitute a sink for atmospheric MeBr.

  4. Methyl bromide emissions from tarped fields

    SciTech Connect

    Cicerone, R.J.; Williams, J.; Wang, N.Y.

    1995-12-31

    Once in the stratosphere, bromine atoms can destroy ozone effectively. Because of this potential effect, certain organobromine compounds including methyl bromide (MeBr) are being controlled or eliminated by national and international regulations. It would be valuable to determine the fraction of MeBr used in soil fumigations that subsequently enters the atmosphere to better assess the need for, and value of, strong regulations. We have designed and conducted several experiments accompanying field fumigations with MeBr/chloropicrin mixtures. In each of three field-fumigation experiments new Irvine, CA in which the fumigated field was covered immediately with plastic tarping, we have deployed static flux chambers on top of the tarping and measured escape fluxes of MeBr. After tarp removal, the same chambers were replaced on the bare soil to continue the measurements. We have also measured soil bromide contents before and after the fumigation. One experiment yielded an escape fraction of 80 to 87% (with 19% remaining as bromide) while the other two experiments yielded escape fractions of 30 to 35% (with about 70% remaining as bromide). This paper will summarize stratospheric bromine chemistry, describe the field experiments and discuss factors that influence emissions, including soil pH, moisture and organic content and injection technique. We acknowledge TriCal, Inc. for many helpful discussions and for professional field applications of MeBr.

  5. Problems with NIOSH method 2520 for methyl bromide

    SciTech Connect

    Tharr, D.

    1994-03-01

    The National Institute for Occupational Safety and Health (NIOSH) publishes the NIOSH Manual of Analytical Methods (NMAM), a collection of analytical methods for characterizing exposures to environmental chemicals. When an industrial hygienist selects a method to monitor worker exposure, it is important to remember that not all the methods in the NMAM have undergone the same level of evaluation, as the following case demonstrates. As part of an industrywide study of the health effects resulting from methyl bromide exposure in structural and agricultural applicators, NIOSH researchers conducted industrial hygiene monitoring for methyl bromide in Florida during July 1990. NIOSH method 2520 was used. This method recommends use of two charcoal tubes (400 mg/100 mg) in series, desorption with carbon disulfide, and analysis by gas chromatography with a flame ionization detector. Sampling results from these surveys indicated a capacity problem. A project was then initiated to determine the reason for the methyl bromide breakthrough that occurred during industrial hygiene monitoring. While conducting research to define and solve this problem, several other problems were identified: reduced adsorption capacity caused by high humidity, difficulty in preparing standard solutions, sample instability, change in recovery with loading, and insufficiently low quantitation limit. The addition of a drying tube to the sampling train, as well as changes to the analytical technique, to the desorption solvent, and to the time till analysis, resulted in an improved method for methyl bromide. This case study demonstrates the importance of noting the conditions under which a method was evaluated and the benefit of testing method performance under conditions likely to exist at a field site. 5 refs.

  6. Photodissociation of methyl chloride and methyl bromide in the atmosphere

    NASA Technical Reports Server (NTRS)

    Robbins, D. E.

    1976-01-01

    Methyl chloride (CH3Cl) and methyl bromide (CH3Br) have been suggested to be significant sources of the stratospheric halogens. The breakup of these compounds in the stratosphere by photodissociation or reaction with OH releases halogen atoms which catalytically destroy ozone. Experimental results are presented for ultraviolet photoabsorption cross sections of CH3Cl and CH3Br. Calculations are presented of loss rates for the methyl halides due to photodissociation and reaction with OH and of mixing ratios of these species in the stratosphere.

  7. The Thz Absorption of Methyl Bromide (CH_3BR)

    NASA Astrophysics Data System (ADS)

    Ramos, Marlon; Drouin, Brian J.

    2011-06-01

    The possibility of monitoring Methyl Bromide is of interest for both environmental and health concerns. It has an ozone depletion potential of 0.2% and falls under regulations of the Clean Air Act. Neurological effects from long term exposure may result from its major use as a pesticide. Recent improvements in microwave limb sounding at mm & submm wavelengths have resulted in retrievals of Methyl Chloride from atmospheric spectra. It is conceivable that Methyl Bromide would also be measurable by this technique. In an effort to extend and improve the previous work, the THz spectrum of Methyl Bromide has been measured at JPL. We used an isotopically enriched 13CH_3Br (90%) sample and recorded spectra from 750 - 1200 GHz. Our assignment covers the CH_379Br, CH_381Br, 13CH_379Br and 13CH_381Br isotopologues with J< 66 and K< 17 for the ground vibrational state. We plan to assign vibrational satellites and investigate possible perturbations near K =12 in the ground state.

  8. Methyl bromide fate in fumigated soils

    SciTech Connect

    Anderson, T.A.; Rice, P.J.; Cink, J.H.

    1995-12-31

    Although widespread use of methyl bromide (MeBr) as a sail and structure fumigant has previously been recognized as a potential significant source of atmospheric MeBr, losses have not been well quantified. Our research indicates that, in laboratory studies, MeBr is volatilized rapidly from fumigated soils and that volatility increases with temperature (35{degrees}C > 25{degrees}C and 15{degrees}C) and moisture (0.03 bar and 0.3 bar > 1 bar > 3 bar). Degradation of MeBr in soil, as indicated by production of bromide ion, was also directly related to temperature and moisture. Most of the soil degradation of MeBr in these studies appears to be abiotic based on the observation of toxicity (reduced microbial respiration) in fumigated soils. We also determined the transformation and movement of MeBr in undisturbed soil columns. These studies also indicated that MeBT volatilizes rapidly (> 50% in 48 h) from soil. In addition, MeBr was not detected in the leachate from the soil columns, however, bromide ion was detected at levels above background 48 h after fumigation and peaked at 5 weeks.

  9. 40 CFR 180.124 - Methyl bromide; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Methyl bromide; tolerances for residues. 180.124 Section 180.124 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances § 180.124 Methyl bromide; tolerances...

  10. 40 CFR 180.124 - Methyl bromide; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Methyl bromide; tolerances for residues. 180.124 Section 180.124 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances § 180.124 Methyl bromide; tolerances...

  11. Atmosphere-plant canopy interactions of methyl bromide

    SciTech Connect

    Taylor, G.E. Jr.; Leonard, T.D.; Gustin, M.S.

    1995-12-31

    In the planetary boundary layer, parcels of air containing background and elevated concentrations of methyl bromide commonly pass through plant canopies in managed (agriculture) and natural (forests, grasslands) ecosystems. It is hypothesized that leaf surfaces are a significant sink or methyl bromide on a local and regional scale and that failure to account for this sink results in a significant overestimation of methyl bromide transport to the stratosphere. Using highly controlled environments, studies are investigating the reactivity of leaf surfaces for methyl bromide at elevated and global background concentrations. Estimates of pathway resistances are being calculated and sites of deposition determined. The results indicate that plant canopies are a significant unrecognized sink for methyl bromide in the atmosphere.

  12. 7 CFR 305.6 - Methyl bromide fumigation treatment schedules.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., fumigation with methyl bromide for sapote fruit fly. Regulated citrus fruits originating inside an area quarantined for sapote fruit fly that are to be moved outside the quarantined area may be treated with...

  13. UV photodissociation of methyl bromide and methyl bromide cation studied by velocity map imaging

    SciTech Connect

    Blanchet, Valerie; Samartzis, Peter C.; Wodtke, Alec M.

    2009-01-21

    We employ the velocity map imaging technique to measure kinetic energy and angular distributions of state selected CH{sub 3} (v{sub 2}=0,1,2,3) and Br ({sup 2}P{sub 3/2}, {sup 2}P{sub 1/2}) photofragments produced by methyl bromide photolysis at 215.9 nm. These results show unambiguously that the Br and Br* forming channels result in different vibrational excitations of the umbrella mode of the methyl fragment. Low energy structured features appear on the images, which arise from CH{sub 3}Br{sup +} photodissociation near 330 nm. The excess energy of the probe laser photon is channeled into CH{sub 3}{sup +} vibrational excitation, most probably in the {nu}{sub 4} degenerate bend.

  14. The oceans: A source or a sink of methyl bromide?

    SciTech Connect

    Pilinis, C.; King, D.B.; Saltzman, E.S.

    1996-04-15

    The global ocean/atmosphere flux of methyl bromide has been estimated from shipboard measurements of the saturation anomaly. When such data are extrapolated globally on the basis of constant saturation anomaly, the ocean is a net sink for methyl bromide [Lobert et al.]. The same data can also be extrapolated on the basis of steady-state production rate of methyl bromide in the water column, allowing regional and seasonal variations in temperature to affect the saturation anomaly. The authors have carried out this type of extrapolation, and they found that the oceans are a strong net source of methyl bromide to the atmosphere. The difference arises mainly due to slow degradation rates in water of higher latitudes. A reduction of the applied production rate by more than 35% is needed in order to switch the ocean from a source to a sink of methyl bromide. These results demonstrate the sensitivity of current estimates of oceanic flux to assumptions about methyl bromide production and destruction in the water column. 19 refs., 2 fig.

  15. Adsorption Isotherm studies of Methyl Bromide adsorbed on Magnesium Oxide

    NASA Astrophysics Data System (ADS)

    Burns, Teresa; Sprung, Michael

    2005-03-01

    Understanding the interaction of polar molecules with ionic surfaces is technologically very important. Using high precision, volumetric adsorption isotherms the layering properties of methyl bromide on the MgO(100) surface were examined between 164 K and 179 K. Methyl bromide (Triple point = 179.49K) is found to exhibit two layering transitions within this temperature interval. Thermodynamic quantities derived from this study including the layering transition temperatures, the 2D compressibility, layer enthalpy and entropy of adsorption, and the isosteric enthalpy of adsorption will be presented. Comparisons with the adsorption properties of methyl chloride and methyl iodide will also be included.

  16. Residential Proximity to Methyl Bromide Use and Birth Outcomes in an Agricultural Population in California

    PubMed Central

    Gemmill, Alison; Gunier, Robert B.; Bradman, Asa; Eskenazi, Brenda

    2013-01-01

    Background: Methyl bromide, a fungicide often used in strawberry cultivation, is of concern for residents who live near agricultural applications because of its toxicity and potential for drift. Little is known about the effects of methyl bromide exposure during pregnancy. Objective: We investigated the relationship between residential proximity to methyl bromide use and birth outcomes. Methods: Participants were from the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) study (n = 442), a longitudinal cohort study examining the health effects of environmental exposures on pregnant women and their children in an agricultural community in northern California. Using data from the California Pesticide Use Reporting system, we employed a geographic information system to estimate the amount of methyl bromide applied within 5 km of a woman’s residence during pregnancy. Multiple linear regression models were used to estimate associations between trimester-specific proximity to use and birth weight, length, head circumference, and gestational age. Results: High methyl bromide use (vs. no use) within 5 km of the home during the second trimester was negatively associated with birth weight (β = –113.1 g; CI: –218.1, –8.1), birth length (β = –0.85 cm; CI: –1.44, –0.27), and head circumference (β = –0.33 cm; CI: –0.67, 0.01). These outcomes were also associated with moderate methyl bromide use during the second trimester. Negative associations with fetal growth parameters were stronger when larger (5 km and 8 km) versus smaller (1 km and 3 km) buffer zones were used to estimate exposure. Conclusions: Residential proximity to methyl bromide use during the second trimester was associated with markers of restricted fetal growth in our study. PMID:23603811

  17. Disposition of [14C]methyl bromide in rats after inhalation.

    PubMed

    Bond, J A; Dutcher, J S; Medinsky, M A; Henderson, R F; Birnbaum, L S

    1985-04-01

    Methyl bromide is used as a disinfectant to fumigate soil and a wide range of stored food commodities in warehouses and mills. Human exposure occurs during the manufacture and use of the chemical. The purpose of this investigation was to determine the disposition and metabolism of [14C]methyl bromide in rats after inhalation. Male Fischer-344 rats were exposed nose only to a vapor concentration of 337 nmol [14C]methyl bromide/liter air (9.0 ppm, 25 degrees C, 620 torr) for 6 hr. Urine, feces, expired air, and tissues were collected for up to 65 hr after exposure. Elimination of 14C as 14CO2 was the major route of excretion with about 47% (3900 nmol/rat) of the total [14C]methyl bromide absorbed excreted by this route. CO2 excretion exhibited a biphasic elimination pattern with 85% of the 14CO2 being excreted with a half-time of 3.9 +/- 0.1 hr (means +/- SE) and 15% excreted with a half-time of 11.4 +/- 0.2 hr. Half-times for elimination of 14C in urine and feces were 9.6 +/- 0.1 and 16.1 +/- 0.1 hr, respectively. By 65 hr after exposure, about 75% of the initial radioactivity had been excreted with 25% remaining in the body. Radioactivity was widely distributed in tissues immediately following exposure with lung (250 nmol equivalents/g), adrenal (240 nmol equivalents/g), kidney (180 nmol equivalents/g), liver (130 nmol equivalents/g), and nasal turbinates (110 nmol equivalents/g) containing the highest concentrations of 14C. Radioactivity in livers immediately after exposure accounted for about 17% of the absorbed methyl bromide. Radioactivity in all other tissues examined accounted for about 10% of the absorbed methyl bromide. Elimination half-times of 14C from tissues were on the order of 1.5 to 8 hr. In all tissues examined, over 90% of the 14C in the tissues was methyl bromide metabolites. The data from this study indicate that after inhalation methyl bromide is rapidly metabolized in tissues and readily excreted.

  18. Methyl bromide emissions from a covered field: II. Volatilization

    SciTech Connect

    Yates, S.R.; Gan, J.; Ernst, F.F.

    1996-01-01

    An experiment to investigate the environmental fate and transport of methyl bromide in agricultural fields is described. The methyl bromide volatilization rate was determined as a function of time for conditions where methyl bromide was applied at a rate of 843 kg in a 3.5-ha (i.e., 240 kg/ha) field covered with plastic at a depth of 25 cm. Three methods were used to estimate the methyl bromide volatilization rate, including: the aerodynamic, theoretical profile shape and integrated horizontal flux methods. The highest methyl bromide volatilization rates were at the beginning of the experiment. Within the first 24 h, approximately 36% of the applied methyl bromide mass was lost. Diurnally, the largest volatilization rates occurred during the day when temperatures were high and the atmosphere was unstable. Cooler temperatures, light winds, and neutral to stable atmospheric conditions were present at night, reducing the flux. The total emission calculated using these methods was found to be approximately 64% ({+-} 10%) of the applied mass. A mass balance was calculated using each flux estimation technique and several methods for analyzing the data. The average mass recovery using all the flux methods was 867 kg ({+-}83 kg), which was 102.8% ({+-}9.8%) of the applied (i.e., 843 kg). The range in the mass balance percent (i.e., percent of applied mass that is measured) is from 88 to 112%. The averaged mass balance percent for the aerodynamic method, which involved using the measured data directly, was approximately 100.8%. The total emission calculated using the aerodynamic method was found to be approximately 62% ({+-}11%) of the applied mass. 29 refs., 7 figs., 1 tab.

  19. REVIEW OF CONTROL OPTIONS FOR METHYL BROMIDE IN COMMODITY TREATMENT

    EPA Science Inventory

    The report describes recent developments in the control of methyl bromide (MeBr) and discusses technical considerations and requirements for and economic feasibility of recovery. (NOTE: MeBr, fumigant for agricultural commodities, is an ozone depleting chemical. The U.S. EPA has ...

  20. Methyl bromide phase out could affect future reforestation efforts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide has long been an integral component in producing healthy tree seedlings in forest nurseries of California, Idaho, Montana, Oregon and Washington. The fumigant was supposed to be completely phased out of use in the United States of America by 2005, but many forest nurseries continue to...

  1. Depleting methyl bromide residues in soil by reaction with bases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Despite generally being considered the most effective soil fumigant, methyl bromide (MeBr) use is being phased out because its emissions from soil can lead to stratospheric ozone depletion. However, a large amount is still currently used due to Critical Use Exemptions. As strategies for reducing the...

  2. Oceanic Uptake of Methyl Bromide: Implications for Oceanic Production

    NASA Astrophysics Data System (ADS)

    Yvon-Lewis, S. A.; Butler, J. H.; King, D. B.; Saltzman, E. S.; Tokarczyk, R.

    2002-12-01

    Methyl bromide (CH3Br) is a source of inorganic bromine (Br) in the stratosphere, where it contributes to the depletion of stratospheric ozone. Unlike the chlorofluorocarbons, which are entirely anthropogenic, methyl bromide has both natural and anthropogenic sources. At ~10 parts per trillion in the troposphere, methyl bromide is believed to be the single largest contributor of stratospheric Br. Once in the stratosphere, Br is approximately 50 times more effective in depleting stratospheric ozone than Cl. However, the budget for CH3Br remains largely unbalanced with known sinks outweighing sources by ~50%. With production and degradation occurring in the ocean, the ocean is both a source and a sink for CH3Br. The balance between production and degradation results in the net undersaturation of CH3Br that has been observed over much of the world's ocean with an estimated global net ocean sink ranging from -11 to -20 Gg/y [King et al., 2000 and references therein]. However, effects of climate change, such as changes in windspeed distribution or sea-surface temperature could alter this balance. Modeling the potential effect of such forcing on the net flux of this important trace gas requires an understanding of the factors controlling the distributions of production and degradation in the surface ocean. During three recent research cruises (North Atlantic, North Pacific, and Southern Ocean), CH3Br degradation rate constants were measured along with saturation anomalies. Here we incorporate these data into a gridded global box model to examine the distribution of oceanic production rates necessary to support the observations. King, D.B., J.H. Butler, S.A. Montzka, S.A. Yvon-Lewis, and J.W. Elkins, Implications of methyl bromide supersaturations in the temperate North Atlantic Ocean, J. of Geophys. Res., 105 (D15), 19763-19769, 2000.

  3. Oral teratogenicity studies of methyl bromide in rats and rabbits.

    PubMed

    Kaneda, M; Hojo, H; Teramoto, S; Maita, K

    1998-05-01

    Teratogenicity studies of methyl bromide, a widely used fumigant, were conducted in rats and rabbits. Methyl bromide was dissolved in corn oil and administered orally to groups of 24 copulated female Crj:CD (SD) rats at dose levels of 0 (corn oil), 3, 10 or 30 mg/kg/day on days 6-15 of gestation and to groups of 18 artificially inseminated female Kbl:JW rabbits at 0, 1, 3 or 10 mg/kg/day on days 6-18 of gestation. Maternal rats and rabbits were euthanized on respective days 20 and 27 of gestation. Foetuses were examined for survival, growth and teratological alterations. Maternal toxicity was evident in the high-dose groups for both species. In these groups, maternal body weight gains and food consumption were significantly decreased during the dosing and post-dosing periods. Necropsy of maternal rats also revealed erosive lesions in the stomach and the surrounding organs. However, no treatment-related adverse effects were found in foetuses of the treated groups for both rat and rabbit studies. These results led to the conclusion that methyl bromide was not foetotoxic or teratogenic to rat and rabbit foetuses up to dose levels of 30 and 10 mg/kg/day, respectively, at which maternal toxicity was evident for both species.

  4. Off-site air monitoring following methyl bromide chamber and building fumigations and evaluation of the ISCST air dispersion model

    SciTech Connect

    Barry, T.; Swgawa, R.; Wofford, P.

    1995-12-31

    The Department of Pesticide Regulation`s preliminary risk characterization of methyl bromide indicated an inadequate margin of safety for several exposure scenarios. Characterization of the air concentrations associated with common methyl bromide use patterns was necessary to determine specific scenarios that result in an unacceptable margin of safety. Field monitoring data were used in conjunction with the Industrial Source Complex, Short Tenn (ISCST) air dispersion model to characterize air concentrations associated with various types of methyl bromide applications. Chamber and building fumigations were monitored and modelled. For each fumigation the emission rates, chamber or building specifications and on-site meteorological data were input into the ISCST model. The model predicted concentrations were compared to measured air concentrations. The concentrations predicted by the ISCST model reflect both the pattern and magnitude of the measured concentrations. Required buffer zones were calculated using the ISCST output.

  5. Bacterial oxidation of methyl bromide in Mono Lake, California

    USGS Publications Warehouse

    Connell, T.L.; Joye, S.B.; Miller, L.G.; Oremland, R.S.

    1997-01-01

    The oxidation of methyl bromide (MeBr) in the water column of Mono Lake, CA, was studied by measuring the formation of H14CO3 from [14C]MeBr. Potential oxidation was detected throughout the water column, with highest rates occurring in the epilimnion (5-12 m depth). The oxidation of MeBr was eliminated by filter-sterilization, thereby demonstrating the involvement of bacteria. Vertical profiles of MeBr activity differed from those obtained for nitrification and methane oxidation, indicating that MeBr oxidation is not simply a co-oxidation process by either nitrifiers or methanotrophs. Furthermore, specific inhibitors of methane oxidation and/or nitrification (e.g., methyl fluoride, acetylene, allyl sulfide) had no effect upon the rate of MeBr oxidation in live samples. Of a variety of potential electron donors added to Mono Lake water, only trimethylamine resulted in the stimulation of MeBr oxidation. Cumulatively, these results suggest that the oxidation of MeBr in Mono Lake waters is attributable to trimethylamine-degrading methylotrophs. Neither methyl chloride nor methanol inhibited the oxidation of [14C]MeBr in live samples, indicating that these bacteria directly oxidized MeBr rather than the products of MeBr nucleophilic substitution reactions.

  6. Acrolein as Potential Alternative to Methyl Bromide in California-Grown Calla Lilies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cut flower and ornamental bulb industries rely heavily on a methyl bromide/chloropicrin (MB/Pic) mixture as a key pest management tool. The loss of methyl bromide (MB) will seriously affect the cut flower and bulb industry, and in the future, will require growers to use alternative fumigants. Theref...

  7. Floriculture Production with Iodomethane, 1, 3-dichloropropene and Chloropicrin as an Alternatie to Methyl Bromide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cut flower growers in California have routinely used methyl bromide and chloropicrin soil fumigation to control soilborne pathogens and weeds. Because of the ban on methyl bromide production and import, alternative treatments are required. Three field trials were established to test alternative trea...

  8. Destruction of methyl bromide sorbed to activated carbon by thiosulfate and electrolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide is widely used as a fumigant for post-harvest and quarantine uses at port facilities due to the low treatment times required, but it is vented to the atmosphere after its use. Due to the potential contributions of methyl bromide to stratospheric ozone depletion, technologies for the c...

  9. Error Evaluation of Methyl Bromide Aerodynamic Flux Measurements

    USGS Publications Warehouse

    Majewski, M.S.

    1997-01-01

    Methyl bromide volatilization fluxes were calculated for a tarped and a nontarped field using 2 and 4 hour sampling periods. These field measurements were averaged in 8, 12, and 24 hour increments to simulate longer sampling periods. The daily flux profiles were progressively smoothed and the cumulative volatility losses increased by 20 to 30% with each longer sampling period. Error associated with the original flux measurements was determined from linear regressions of measured wind speed and air concentration as a function of height, and averaged approximately 50%. The high errors resulted from long application times, which resulted in a nonuniform source strength; and variable tarp permeability, which is influenced by temperature, moisture, and thickness. The increase in cumulative volatilization losses that resulted from longer sampling periods were within the experimental error of the flux determination method.

  10. Methyl bromide emissions from a covered field: I. Experimental conditions and degradation in soil

    SciTech Connect

    Yates, S.R.; Gan, J.; Ernst, F.F.

    1996-01-01

    An experiment is described to investigate the environmental fate and transport of methyl bromide in agricultural systems. The experiment was designed to determine the dynamics of methyl bromide movement through soil, degradation, and total emissions to the atmosphere. This is of particular interest because it will allow an assessment of the environmental impacts (i.e., stratospheric ozone depletion) resulting from the agricultural use of methyl bromide. Methyl bromide was applied at a rate of 843 kg in a 3.5-ha (i.e., 240 kg/ha) field at a depth of 0.25 m and covered with a sheet of 1-mil polyethylene plastic. The maximum methyl bromide concentration in the atmosphere occurred at night between 0200 and 0600 h. During the first 3 d of the experiment, the maximum daily concentrations at 0.2 m above the soil surface were 30, 5, and 1 mg/(m{sup 3} of air), respectively. The trend of reduced emissions with time continued until the plastic was removed, when a momentary increase in the methyl bromide emissions occurred. The maximum soil gas concentration 24 h after injection was 30 g/m{sup 3} located at a 0.25-m depth. When the plastic was removed from the field (at 5.6 d), the maximum soil gas concentration was approximately 2 g/m{sup 3} at a 0.5-m depth. A mass-difference method for estimating the total methyl bromide emissions from the soil, based on degradation of methyl bromide to Br{sup -}, indicates that approximately 39% or 325 kg ({+-} 164 kg) of the applied methyl bromide was converted to Br{sup -} and, therefore, 61% or 518 kg ({+-} 164 kg) was lost via volatilization. 16 refs., 11 figs., 2 tabs.

  11. Atmospheric methyl bromide: Trends and global mass balance

    SciTech Connect

    Khalil, M.A.K.; Rasmussen, R.A.; Gunawardena, R. )

    1993-02-20

    Atmospheric methyl bromide is of considerable environmental importance as the largest reservoir of gaseous bromine in the atmosphere. Bromine gases can catalytically destroy stratospheric ozone. Since agricultural activities, automobiles, biomass burning, and other human activities produce CH[sub 3]Br, it is of interest to know its global mass balance and particularly the specific sources and sinks. In this paper the authors provide a decadal time series of global CH[sub 3]Br concentrations in the Earth's atmosphere. The data show that average concentrations are about 10 pptv and during the last 4 years may be increasing at 0.3 [plus minus] 0.1 pptv/yr (3%/yr [plus minus] 1%/yr). They estimate that the atmospheric lifetime of CH[sub 3]Br that is due to reaction with OH, is about 2 years, resulting in a calculated global emission rate of about 100 Gy/yr. Ocean supersaturations of 140-180% are observed, and atmospheric concentrations over the open oceans are higher than at comparably located coastal sites. The ocean source is estimated to be about 35 Gg/yr. The remaining emissions must come from other natural sources and anthropogenic activities. The results are based on some 2,200 samples obtained over more than a decade. Mass balance calculations explain most aspects of the present data but other implications are not easily reconciled, leaving open the possibility of undiscovered sources and sinks. 20 refs., 5 figs., 4 tabs.

  12. Bioreactors for removing methyl bromide following contained fumigations

    USGS Publications Warehouse

    Miller, L.G.; Baesman, S.M.; Oremland, R.S.

    2003-01-01

    Use of methyl bromide (MeBr) as a quarantine, commodity, or structural fumigant is under scrutiny because its release to the atmosphere contributes to the depletion of stratospheric ozone. A closed-system bioreactor consisting of 0.5 L of a growing culture of a previously described bacterium, strain IMB-1, removed MeBr (> 110 ??mol L-1) from recirculating air. Strain IMB-1 grew slowly to high cell densities in the bioreactor using MeBr as its sole carbon and energy source. Bacterial oxidation of MeBr produced CO2 and hydrobromic acid (HBr), which required continuous neutralization with NaOH for the system to operate effectively. Strain IMB-1 was capable of sustained oxidation of large amounts of MeBr (170 mmol in 46 d). In an open-system bioreactor (10-L fermenter), strain IMB-1 oxidized a continuous supply of MeBr (220 ??mol L-1 in air). Growth was continuous, and 0.5 mol of MeBr was removed from the air supply in 14 d. The specific rate of MeBr oxidation was 7 ?? 10-16 mol cell-1 h-1. Bioreactors such as these can therefore be used to remove large quantities of contaminant MeBr, which opens the possibility of biodegradation as a practical means for its disposal.

  13. Reactive films for mitigating methyl bromide emissions from fumigated soil.

    PubMed

    Xuan, Richeng; Ashworth, Daniel J; Luo, Lifang; Yates, Scott R

    2011-03-15

    Emissions of methyl bromide (MeBr) from agricultural fumigation can lead to depletion of the stratospheric ozone layer, and so its use is being phased out. However, as MeBr is still widely used under Critical Use Exemptions, strategies are still required to control such emissions. In this work, novel reactive films (RFs) were designed and their efficacy in limiting loss of MeBr from soil was tested. A reactive layer, containing dry ammonium thiosulfate (ATS), was sandwiched between two layers of plastic film, the lower layer being HDPE (high-density polyethylene film, which is permeable to MeBr) and the upper layer HDPE or VIF (virtually impermeable film). MeBr diffusion through, and transformation by, the RFs were tested in a stainless-steel permeability cell. Although ineffective when dry, the RFs substantially depleted MeBr when activated with water to produce ATS solution. MeBr half-life (t(1/2)) was around 9.0 h at 20 °C in the presence of activated RF, and was sensitive to temperature (t(1/2) 15.7 and 2.9 h at 10 and 40 °C, respectively). When the upper film layer was VIF, less than 0.15% of the added MeBr diffused through the film, with the remainder being transformed within the reactive layer. These findings indicate that such films have good potential to reduce MeBr loss from fumigated soils to the atmosphere.

  14. 76 FR 7200 - Methyl Bromide; Notice of Receipt of Requests To Voluntarily Amend Registrations To Terminate...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-09

    ... Certain Soil Uses AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: In accordance... bromide product registrations to terminate or delete one or more soil uses. The requests would delete all methyl bromide soil uses that do not meet the definition of a ``critical use,'' a...

  15. Fumigation of jute bags with ethylene oxide and methyl bromide to eradicate potato ring rot bacteria.

    PubMed

    RICHARDSON, L T; MONRO, H A

    1962-09-01

    In a series of full-scale tests, the effectiveness of various fumigant treatments for the eradication of potato ring rot bacteria from bulk lots of contaminated jute bags was evaluated. Survival of these bacteria on infested sample fibers located at various positions within and around a tightly wired bale was determined quantitatively from the growth lag in a liquid medium as indicated by the rate of turbidity development.Ethylene oxide, though highly toxic to Corynebacterium sepedonicum in laboratory tests, failed to penetrate the jute sufficiently to be effective in the interior of a bale. Methyl bromide showed better penetration, but was not sufficiently toxic at practical dosage levels. A mixture of 5% ethylene oxide and 10% methyl bromide achieved complete eradication throughout a bale in an 18-hr exposure period. On the basis of these results, eradication of ring rot bacteria from contaminated jute bags by fumigation with a combination of these two gases would appear to be feasible under commercial conditions.

  16. Carbon isotope fractionation of methyl bromide during agricultural soil fumigations

    USGS Publications Warehouse

    Bill, M.; Miller, L.G.; Goldstein, Allen H.

    2002-01-01

    The isotopic composition of methyl bromide (CH3Br) has been suggested to be a potentially useful tracer for constraining the global CH3Br budget. In order to determine the carbon isotopic composition of CH3Br emitted from the most significant anthropogenic application (pre-plant fumigation) we directly measured the ??13C of CH3Br released during commercial fumigation. We also measured the isotopic fractionation associated with degradation in agricultural soil under typical field fumigation conditions. The isotopic composition of CH3Br collected in soil several hours after injection of the fumigant was -44.5??? and this value increased to -20.7??? over the following three days. The mean kinetic isotope effect (KIE) associated with degradation of CH3Br in agricultural soil (12???) was smaller than the reported value for methylotrophic bacterial strain IMB-1, isolated from previously fumigated agricultural soil, but was similar to methylotrophic bacterial strain CC495, isolated from a pristine forest litter zone. Using this fractionation associated with the degradation of CH3Br in agricultural soil and the mean ??13C of the industrially manufactured CH3Br (-54.4???), we calculate that the agricultural soil fumigation source has a carbon isotope signature that ranges from -52.8??? to -42.0???. Roughly 65% of industrially manufactured CH3Br is used for field fumigations. The remaining 35% is used for structural and post-harvest fumigations with a minor amount used during industrial chemical manufacturing. Assuming that the structural and post-harvest fumigation sources of CH3Br are emitted without substantial fractionation, we calculate that the ??13C of anthropogenically emitted CH3Br ranges from -53.2??? to -47.5???.

  17. Bacterial oxidation of methyl bromide in fumigated agricultural soils

    USGS Publications Warehouse

    Miller, L.G.; Connell, T.L.; Guidetti, J.R.; Oremland, R.S.

    1997-01-01

    The oxidation of [14C]methyl bromide ([14C]MeBr) to 14CO2 was measured in field experiments with soils collected from two strawberry plots fumigated with mixtures of MeBr and chloropicrin (CCI3NO2). Although these fumigants are considered potent biocides, we found that the highest rates of MeBr oxidation occurred 1 to 2 days after injection when the fields were tarped, rather than before or several days after injection. No oxidation of MeBr occurred in heat-killed soils, indicating that microbes were the causative agents of the oxidation. Degradation of MeBr by chemical and/or biological processes accounted for 20 to 50% of the loss of MeBr during fumigation, with evasion to the atmosphere inferred to comprise the remainder. In laboratory incubations, complete removal of [14C]MeBr occurred within a few days, with 47 to 67% of the added MeBr oxidized to 14CO2 and the remainder of counts associated with the solid phase. Chloropicrin inhibited the oxidation of MeBr, implying that use of this substance constrains the extent of microbial degradation of MeBr during fumigation. Oxidation was by direct bacterial attack of MeBr and not of methanol, a product of the chemical hydrolysis of MeBr. Neither nitrifying nor methane-oxidizing bacteria were sufficiently active in these soils to account for the observed oxidation of MeBr, nor could the microbial degradation of MeBr be linked to cooxidation with exogenously supplied electron donors. However, repeated addition of MeBr to live soils resulted in higher rates of its removal, suggesting that soil bacteria used MeBr as an electron donor for growth. To support this interpretation, we isolated a gram-negative, aerobic bacterium from these soils which grew with MeBr as a sole source of carbon and energy.

  18. The fate of alternative soil fumigants to methyl bromide

    NASA Astrophysics Data System (ADS)

    Qin, R.; Gao, S.

    2011-12-01

    Soil fumigation is an important agricultural practice for the control of soil-borne pests. Since the phase-out of methyl bromide, due to its role in the depletion of stratospheric ozone, several alternatives such as 1,3-dichloropropene (1,3-D), chloropicrin (CP), and dimethyl disulfide (DMDS) are being increasingly used. The major processes and factors affecting the fate of these chemicals are evaluated. The high volatility of fumigants leads to high emission loss when no proper containment is used. Recent tarping technology using low permeability films can significantly reduce emissions. Fumigant degradation rate becomes critical to the determination of fumigation rate that affects efficacy and residence time in soil. A series of laboratory incubation experiments were carried out to determine degradation rate of 1,3-D isomers, CP and DMDS in five different soils collected from California and Florida. Fumigant degradation rates depend highly on the amounts of fumigants in soil, chemical characteristics, and soil conditions. Fumigant degradation rate were found to increase for all fumigants as the fumigant amounts in soil decreased. The changes were smaller for 1,3-D isomers compared to CP and DMDS. In soils with the lowest application rate, the degradation rate of fumigants is in the order of CP > DMDS > cis-1,3-D > trans-1,3-D. Soil and environmental factors also affect fumigant degradation rate. These findings suggest that a proper application rate should be determined for specific fumigants in a soil when using low permeability tarp in order to achieve sufficient fumigation efficacy during a certain period of time while minimizing potential surge of emissions after tarp removal and/or long residence time in soil that may cause phytotoxicity or leaching.

  19. Methyl chloride and methyl bromide emissions from baking: an unrecognized anthropogenic source.

    PubMed

    Thornton, Brett F; Horst, Axel; Carrizo, Daniel; Holmstrand, Henry

    2016-05-01

    Methyl chloride and methyl bromide (CH3Cl and CH3Br) are the largest natural sources of chlorine and bromine, respectively, to the stratosphere, where they contribute to ozone depletion. We report the anthropogenic production of CH3Cl and CH3Br during breadbaking, and suggest this production is an abiotic process involving the methyl ester functional groups in pectin and lignin structural polymers of plant cells. Wide variations in baking styles allow only rough estimates of this flux of methyl halides on a global basis. A simple model suggests that CH3Br emissions from breadbaking likely peaked circa 1990 at approximately 200tonnes per year (about 0.3% of industrial production), prior to restrictions on the dough conditioner potassium bromate. In contrast, CH3Cl emissions from breadbaking may be of similar magnitude as acknowledged present-day CH3Cl industrial emissions. Because the mechanisms involve functional groups and compounds widely found in plant materials, this type of methyl halide production may occur in other cooking techniques as well. PMID:26878644

  20. Methyl chloride and methyl bromide emissions from baking: an unrecognized anthropogenic source.

    PubMed

    Thornton, Brett F; Horst, Axel; Carrizo, Daniel; Holmstrand, Henry

    2016-05-01

    Methyl chloride and methyl bromide (CH3Cl and CH3Br) are the largest natural sources of chlorine and bromine, respectively, to the stratosphere, where they contribute to ozone depletion. We report the anthropogenic production of CH3Cl and CH3Br during breadbaking, and suggest this production is an abiotic process involving the methyl ester functional groups in pectin and lignin structural polymers of plant cells. Wide variations in baking styles allow only rough estimates of this flux of methyl halides on a global basis. A simple model suggests that CH3Br emissions from breadbaking likely peaked circa 1990 at approximately 200tonnes per year (about 0.3% of industrial production), prior to restrictions on the dough conditioner potassium bromate. In contrast, CH3Cl emissions from breadbaking may be of similar magnitude as acknowledged present-day CH3Cl industrial emissions. Because the mechanisms involve functional groups and compounds widely found in plant materials, this type of methyl halide production may occur in other cooking techniques as well.

  1. The ocean in near equilibrium with atmospheric methyl bromide

    NASA Astrophysics Data System (ADS)

    Hu, Lei; Yvon-Lewis, Shari; Liu, Yina; Bianchi, Thomas S.

    2012-09-01

    Saturation-anomaly measurements of methyl bromide (CH3Br) were made in the eastern Pacific (3/30-4/27, 2010) and the eastern Atlantic (10/25-11/26, 2010) to assess the oceanic saturation state as the phaseout of fumigation - non-Quarantine and Pre-Shipment (non-QPS) uses of CH3Br nears completion and atmospheric concentrations continue to decline. These cruises occurred 16 years after the Bromine Latitudinal Air-Sea Transect (BLAST) cruises, which were conducted in the same regions and first established a global oceanic net sink of -12.6 Gg yr-1 for atmospheric CH3Br in 1994. Results from this study suggest saturation anomalies of CH3Br in the surface ocean have become less negative than those observed 16 years ago as the atmospheric burden has declined over the past decade. The global net sea-to-air flux was estimated at 0 to 3 Gg yr-1 in 2010, suggesting that the ocean may become a net small source to atmospheric CH3Br. There are no significant differences between this study and previous studies for measured biological loss rate constants and calculated annual production rates, suggesting that annual production rates and biological degradation rate constants for CH3Br in the surface ocean have likely remained relatively constant over the past 16 years. When including the biological loss rate constants from this study and all previous studies, the mean global biological loss rate constant is constrained to 0.05 ± 0.01 d-1 (at a 95% confidence level). Combining chemical and eddy degradation rate constants, and using an updated gas transfer velocity, we estimate the CH3Br partial atmospheric lifetime with respect to oceanic loss to be 3.1 (2.3 to 5.0) years. Although the new partial atmospheric lifetime is about 1.3 years longer than the best prior estimate, it does not change the overall atmospheric lifetime of CH3Br, 0.8 (0.7-0.9) years.

  2. Determination of methyl bromide in air samples by headspace gas chromatography

    SciTech Connect

    Woodrow, J.E.; McChesney, M.M.; Seiber, J.N.

    1988-03-01

    Methyl bromide is extensively used in agriculture (4 x 10/sup 6/ kg for 1985 in California alone as a fumigant to control nematodes, weeds, and fungi in soil and insect pests in harvested grains and nuts. Given its low boiling point (3.8/sup 0/C) and high vapor pressure (approx. 1400 Torr at 20/sup 0/C), methyl bromide will readily diffuse if not rigorously contained. Methods for determining methyl bromide and other halocarbons in air vary widely. A common practice is to trap the material from air on an adsorbent, such as polymeric resins, followed by thermal desorption either directly into the analytical instrumentation or after intermediary cryofocusing. While in some cases analytical detection limits were reasonable (parts per million range), many of the published methods were labor intensive and required special handling techniques that precluded high sample throughput. They describe here a method for the sampling and analysis of airborne methyl bromide that was designed to handle large numbers of samples through automating some critical steps of the analysis. The result was a method that allowed around-the-clock operation with a minimum of operator attention. Furthermore, the method was not specific to methyl bromide and could be used to determine other halocarbons in air.

  3. Methyl bromide: ocean sources, ocean sinks, and climate sensitivity.

    PubMed

    Anbar, A D; Yung, Y L; Chavez, F P

    1996-03-01

    The oceans play an important role in the geochemical cycle of methyl bromide (CH3Br), the major carrier of O3-destroying bromine to the stratosphere. The quantity of CH3Br produced annually in seawater is comparable to the amount entering the atmosphere each year from natural and anthropogenic sources. The production mechanism is unknown but may be biological. Most of this CH3Br is consumed in situ by hydrolysis or reaction with chloride. The size of the fraction which escapes to the atmosphere is poorly constrained; measurements in seawater and the atmosphere have been used to justify both a large oceanic CH3Br flux to the atmosphere and a small net ocean sink. Since the consumption reactions are extremely temperature-sensitive, small temperature variations have large effects on the CH3Br concentration in seawater, and therefore on the exchange between the atmosphere and the ocean. The net CH3Br flux is also sensitive to variations in the rate of CH3Br production. We have quantified these effects using a simple steady state mass balance model. When CH3Br production rates are linearly scaled with seawater chlorophyll content, this model reproduces the latitudinal variations in marine CH3Br concentrations observed in the east Pacific Ocean by Singh et al. [1983] and by Lobert et al. [1995]. The apparent correlation of CH3Br production with primary production explains the discrepancies between the two observational studies, strengthening recent suggestions that the open ocean is a small net sink for atmospheric CH3Br, rather than a large net source. The Southern Ocean is implicated as a possible large net source of CH3Br to the atmosphere. Since our model indicates that both the direction and magnitude of CH3Br exchange between the atmosphere and ocean are extremely sensitive to temperature and marine productivity, and since the rate of CH3Br production in the oceans is comparable to the rate at which this compound is introduced to the atmosphere, even small

  4. Methyl bromide: ocean sources, ocean sinks, and climate sensitivity.

    PubMed

    Anbar, A D; Yung, Y L; Chavez, F P

    1996-03-01

    The oceans play an important role in the geochemical cycle of methyl bromide (CH3Br), the major carrier of O3-destroying bromine to the stratosphere. The quantity of CH3Br produced annually in seawater is comparable to the amount entering the atmosphere each year from natural and anthropogenic sources. The production mechanism is unknown but may be biological. Most of this CH3Br is consumed in situ by hydrolysis or reaction with chloride. The size of the fraction which escapes to the atmosphere is poorly constrained; measurements in seawater and the atmosphere have been used to justify both a large oceanic CH3Br flux to the atmosphere and a small net ocean sink. Since the consumption reactions are extremely temperature-sensitive, small temperature variations have large effects on the CH3Br concentration in seawater, and therefore on the exchange between the atmosphere and the ocean. The net CH3Br flux is also sensitive to variations in the rate of CH3Br production. We have quantified these effects using a simple steady state mass balance model. When CH3Br production rates are linearly scaled with seawater chlorophyll content, this model reproduces the latitudinal variations in marine CH3Br concentrations observed in the east Pacific Ocean by Singh et al. [1983] and by Lobert et al. [1995]. The apparent correlation of CH3Br production with primary production explains the discrepancies between the two observational studies, strengthening recent suggestions that the open ocean is a small net sink for atmospheric CH3Br, rather than a large net source. The Southern Ocean is implicated as a possible large net source of CH3Br to the atmosphere. Since our model indicates that both the direction and magnitude of CH3Br exchange between the atmosphere and ocean are extremely sensitive to temperature and marine productivity, and since the rate of CH3Br production in the oceans is comparable to the rate at which this compound is introduced to the atmosphere, even small

  5. Methyl bromide: ocean sources, ocean sinks, and climate sensitivity

    NASA Technical Reports Server (NTRS)

    Anbar, A. D.; Yung, Y. L.; Chavez, F. P.

    1996-01-01

    The oceans play an important role in the geochemical cycle of methyl bromide (CH3Br), the major carrier of O3-destroying bromine to the stratosphere. The quantity of CH3Br produced annually in seawater is comparable to the amount entering the atmosphere each year from natural and anthropogenic sources. The production mechanism is unknown but may be biological. Most of this CH3Br is consumed in situ by hydrolysis or reaction with chloride. The size of the fraction which escapes to the atmosphere is poorly constrained; measurements in seawater and the atmosphere have been used to justify both a large oceanic CH3Br flux to the atmosphere and a small net ocean sink. Since the consumption reactions are extremely temperature-sensitive, small temperature variations have large effects on the CH3Br concentration in seawater, and therefore on the exchange between the atmosphere and the ocean. The net CH3Br flux is also sensitive to variations in the rate of CH3Br production. We have quantified these effects using a simple steady state mass balance model. When CH3Br production rates are linearly scaled with seawater chlorophyll content, this model reproduces the latitudinal variations in marine CH3Br concentrations observed in the east Pacific Ocean by Singh et al. [1983] and by Lobert et al. [1995]. The apparent correlation of CH3Br production with primary production explains the discrepancies between the two observational studies, strengthening recent suggestions that the open ocean is a small net sink for atmospheric CH3Br, rather than a large net source. The Southern Ocean is implicated as a possible large net source of CH3Br to the atmosphere. Since our model indicates that both the direction and magnitude of CH3Br exchange between the atmosphere and ocean are extremely sensitive to temperature and marine productivity, and since the rate of CH3Br production in the oceans is comparable to the rate at which this compound is introduced to the atmosphere, even small

  6. Dispersion characteristics and sinks for methyl bromide vapors downwind of treated agricultural fields

    SciTech Connect

    Seiber, J.N.; Woodrow, J.E.; Dowling, K.

    1995-12-31

    A study of methyl bromide volatilization and fate from a treated agricultural field was conducted in Monterey County, California, in 1994. Air concentrations were measured above and downwind from the field with the objective of comparing vertical and horizontal flux terms. Another objective was to compare observed downwind concentrations with those predicted by the Industrial Source Complex model, to begin the process of identifying potential sinks which might scavenge methyl bromide from the atmosphere. The final objective was to determine the limit of detection of our analytical method for airborne methyl bromide using field samples representing a wide range of concentrations. A description of the methods and results of the study will be presented, along with a discussion of data quality and interpretation.

  7. Efficacy of Methyl Bromide for Control of Different Life Stages of Stored-Product Psocids.

    PubMed

    Athanassiou, Christos G; Hasan, M Mahbub; Phillips, Thomas W; Aikins, M Jamie; Throne, James E

    2015-06-01

    The psocid species Liposcelis paeta Pearman, Liposcelis entomophila (Enderlein), Liposcelis decolor (Pearman), Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae), and Lepinotus reticulatus Enderlein (Psocoptera: Trogiidae) were evaluated in laboratory bioassays to determine their susceptibility to six concentrations of methyl bromide (0.027, 0.113, 0.280, 0.393, 0.452, and 0.616 g/m3) after 48 h of exposure at 27.5°C. The life stages that were evaluated were adults (for all species), nymphs (for all species except Lep. reticulatus), and eggs (for L. entomophila, L. decolor, and L. bostrychophila). Adults and nymphs were very susceptible, and complete mortality was recorded at concentrations between 0.027 and 0.280 g/m3. In contrast, eggs were by far more tolerant than adults and nymphs for all species tested. At 0.027 g/m3, mortality did not exceed 53%, while survival was high even at 0.113 g/m3. Complete (100%) egg mortality was recorded at 0.393 g/m3 for L. decolor and at 0.452 g/m3 for L. entomophila and L. bostrychophila; concentrations estimated to give 99% mortality for eggs of these three species were 0.710, 1.044, and 0.891 g/m3, respectively. These results show that stored-product psocids are susceptible to methyl bromide, but concentrations of ≥0.452 g/m3 should be used to control all life stages. PMID:26470271

  8. Disposition of [14C]methyl bromide in Fischer-344 rats after oral or intraperitoneal administration.

    PubMed

    Medinsky, M A; Bond, J A; Dutcher, J S; Birnbaum, L S

    1984-09-14

    Methyl bromide is used as a disinfectant to fumigate soil. The intent of our study was to determine the disposition of methyl bromide following a single acute administration. Male Fischer-344 rats were given 250 mumol of [14C] methyl bromide/kg body wt by either oral or i.p. administration. Urine, feces and expired air were collected and at the end of 72 h the rats were sacrificed and tissues analyzed to determine 14C excretion and tissue distribution. After i.p. administration of methyl bromide, the dominant route of excretion was exhalation of 14CO2, with 46% of the dose exhaled as 14CO2. In contrast, urinary excretion of 14C was the major route of elimination (43% of the dose) when methyl bromide was given orally. Very little of the 14C appeared in the feces (less than 3% of the dose) regardless of route of administration. In rats with bile duct cannulations, 46% of an oral dose appeared in the bile over a 24-h period. Collection of bile significantly decreased the exhalation of 14CO2 and 14C excreted in urine compared to controls. At 72 h after oral or i.p. administration, 14-17% of the 14C remained in the rats, with liver and kidney being the major organs of retention. Results indicate that route of administration can affect the pathways for excretion. In addition, excretion of 14C in bile, coupled with the low levels of radioactivity found in the feces, indicates that reabsorption of biliary metabolites from the gut plays a significant role in the disposition of [14C] methyl bromide.

  9. Acute toxicity and superficial damage to goldfish from the ionic liquid 1-methyl-3-octylimidazolium bromide.

    PubMed

    Li, Xiao-Yu; Zeng, Shi-Hu; Zhang, Wei-Hong; Liu, Li; Ma, Shuai; Wang, Jian-Ji

    2013-04-01

    In the present study, goldfish toxicity and superficial damage from 1-methyl-3-octylimidazolium bromide ([C8 mim]Br) exposure were evaluated by an acute toxicity test. These results show that the 24-h 50% lethal concentration for [C8 mim]Br in goldfish is 244 mg L(-1) , and this indicates that [C8 mim]Br is a chemical with moderate or low toxicity to organisms. Scanning electronic microscope and histological observations revealed that acute exposure to [C8 mim]Br induced obvious superficial damage to the skin, gill filaments, and intestinal villi of the goldfish, and this suggests that the skin, gills, and intestines may be the first direct targets of the ionic liquid in this fish. Histological examination also indicated that [C8 mim]Br-exposure caused damage to the goldfish's hepatopancreas and kidney, consisting mainly of hepatic cords in a loose connection, hepatic cytoplasmic vacuolation, renal parenchyma vacuolization, and intumescence of the renal tubule. In addition, we found that [C8 mim]Br caused a significant increase in malondialdehyde (MDA) level in the hepatopancreases from these goldfish, and thus we suggest that the MDA level may be a biomarker of [C8 mim]Br-toxicity in goldfish.

  10. 77 FR 48153 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-13

    ... for 2015, Deadline Extension AGENCY: Environmental Protection Agency (EPA). ACTION: Extension to... 2015. On August 3, 2012, EPA received a letter from methyl bromide stakeholders requesting an extension... applicants. Critical Use Exemption Applications for 2015 are now due to the agency on or before August...

  11. Methyl bromide release from activated carbon and the soil/water/carbon interface

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl Bromide (MB) is a major source of stratospheric bromine radical, a known depletor of ozone. The use of ozone-depleting chemicals, including MB, is regulated by the Montreal Protocol. Critical uses of MB are permitted, such as when postharvest fumigation is mandated by an importing country. Fo...

  12. 75 FR 41177 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-15

    ... extent, and by means of the procedures, set forth under 40 CFR part 2 subpart B; 41 FR 36752, 43 FR 40000, 50 FR 51661. If no claim of confidentiality accompanies the information when EPA receives it, EPA may... AGENCY Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption...

  13. Reduced rates and alternatives to methyl bromide for snapdragon production in Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A field trial was conducted to evaluate soil solarization, Midas™ (iodomethane:chloropicrin 50:50, Arysta LifeScience Corp., Cary, NC) and different rates and formulations of methyl bromide under standard and metalized films for the production of snapdragon (Antirrhinum majus) in Martin County, Flor...

  14. WEED COMMUNITY COMPOSITION IN TREE FRUIT NURSERIES TREATED WITH METHYL BROMIDE AND ALTERNATIVE FUMIGANTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several agricultural cropping systems, for decades, have relied on methyl bromide (MeBr) for pest control including weeds. Alternative fumigants are being sought worldwide because MeBr has been identified as an ozone-layer depleting substance. Weed communities respond dynamically to alterations in...

  15. Forest nurseries face critical choices with the loss of methyl bromide fumigation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Forest nurseries in the western United States have relied for decades on methyl bromide for the control of soilborne pathogens such as Cylindrocarpoin, Fusarium, and Pythium species that affect bareroot tree seedling production. However, increased state and federal regulations have led to a substan...

  16. 77 FR 29341 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-17

    ... to the provisions of the Montreal Protocol on Substances that Deplete the Ozone Layer for... AGENCY Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications... FURTHER INFORMATION CONTACT: General Information: U.S. EPA Stratospheric Ozone Information Hotline,...

  17. Methyl bromide and sulfuryl fluoride effectiveness against red flour beetle life stages

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The efficacy of methyl bromide (MB) and sulfuryl fluoride (SF) for managing all life stages of the red flour beetle, Tribolium castaneum, was investigated in the Hal Ross Flour Mill at Kansas State University. Eggs, young larvae, large larvae, pupae, and adults confined in plastic compartments with ...

  18. Steam disinfestation as a methyl bromide alternative in California cut flower nurseries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Steam may be an effective alternative to methyl bromide in cut flower production in California. Advantages of steam include broad spectrum pest control and a zero hour re-entry interval. The principle disadvantage of sheet steaming is cost effectiveness due to current energy prices and application...

  19. Evaluation of Reduced Methyl Bromide Rates in Field Grown Perennial Crop Nurseries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Preplant soil fumigation with methyl bromide (MB) has commonly been used in field grown nursery crops to provide broad-spectrum control of plant parasitic nematodes, disease pathogens, and weed propagules. Although MB use was officially phased out in 2005 due to negative effects on stratospheric oz...

  20. 76 FR 29238 - Methyl Bromide; Cancellation Order for Registration Amendments To Terminate Certain Soil Uses

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-20

    ... provided, EPA received no comments in response to the February 9, 2011, Federal Register notice (76 FR 7200... AGENCY Methyl Bromide; Cancellation Order for Registration Amendments To Terminate Certain Soil Uses... for the amendments to terminate soil uses, voluntarily requested by the registrants and accepted...

  1. Headspace gas chromatographic method for determination of methyl bromide in food ingredients

    SciTech Connect

    DeVries, J.W.; Broge, J.M.; Schroeder, J.P.; Bowers, R.H.; Larson, P.A.; Burns, N.M.

    1985-11-01

    A headspace gas chromatographic (GC) method, which can be automated, has been developed for determination of methyl bromide. This method has been applied to wheat, flour, cocoa, and peanuts. Samples to be analyzed are placed in headspace sample vials, water is added, and the vials are sealed with Teflon-lined septa. After an appropriate equilibration time at 32 degrees C, the samples are analyzed within 10 h. A sample of the headspace is withdrawn and analyzed on a gas chromatograph equipped with an electron capture detector (ECD). Methyl bromide levels were quantitated by comparison of peak area with a standard. The standard was generated by adding a known amount of methyl bromide to a portion of the matrix being analyzed and which was known to be methyl bromide free. The detection limit of the method was 0.4 ppb. The coefficient of variation (CV) was 6.5% for wheat, 8.3% for flour, 3.3% for cocoa, and 11.6% for peanuts.

  2. EVALUATION OF CONTAINMENT AND CONTROL OPTIONS FOR METHYL BROMIDE IN COMMODITY TREATMENT

    EPA Science Inventory

    The report gives results of an investigation of means for methyl bromide (MeBr) recovery, reuse, and destruction to prevent atmospheric emissions if its limited use were still allowed. (NOTE: MeBr is an ozone-depleting chemical scheduled to be phased out by the Clean Air Act by t...

  3. Leisingera methylohalidivorans gen. nov., sp. nov., a marine methylotroph that grows on methyl bromide

    USGS Publications Warehouse

    Schaefer, J.K.; Goodwin, K.D.; McDonald, I.R.; Murrell, J.C.; Oremland, R.S.

    2002-01-01

    A marine methylotroph, designated strain MB2T, was isolated for its ability to grow on methyl bromide as a sole carbon and energy source. Methyl chloride and methyl iodide also supported growth, as did methionine and glycine betaine. A limited amount of growth was observed with dimethyl sulfide. Growth was also noted with unidentified components of the complex media marine broth 2216, yeast extract and Casamino acids. No growth was observed on methylated amines, methanol, formate, acetate, glucose or a variety of other substrates. Growth on methyl bromide and methyl iodide resulted in their oxidation to CO2 with stoichiometric release of bromide and iodide, respectively. Strain MB2T exhibited growth optima at NaCl and Mg2+ concentrations similar to that of seawater. Phylogenetic analysis of the 16S rDNA sequence placed this strain in the ??-Proteobacteria in proximity to the genera Ruegeria and Roseobacter. It is proposed that strain MB2T (= ATCC BAA-92T = DSM 14336T) be designated Leisingera methylohalidivorans gen. nov., sp. nov.

  4. Characterization of methyl bromide and methyl chloride fluxes at temperate freshwater wetlands

    NASA Astrophysics Data System (ADS)

    Hardacre, Catherine J.; Heal, Mathew R.

    2013-01-01

    Methyl bromide (CH3Br) and methyl chloride (CH3Cl) are important natural sources of halogens to the atmosphere. A total of 568 CH3Br and 418 CH3Cl net flux measurements were made for up to 2 years at the same locations within four different wetlands in Scotland. Mean (± 1 standard deviation (SD)) CH3Br and CH3Cl net fluxes across all measurements at each wetland were: Auchencorth Moss, 8 (± 7) and 3560 (± 1260) ng m-2 h-1; Old Castle Farm, 420 (± 70) and 500 (± 260) ng m-2 h-1; Red Moss of Balerno, 500 (± 90) and 140,000 (± 36,000) ng m-2 h-1; and St Margaret's Marsh, 3600 (± 600) and -270 (± 450) ng m-2 h-1. None of the wetlands was a large net sink. Where substantial emissions were observed, these followed seasonal trends, increasing early in the growing season and declining in early autumn. Some diurnal cycles were observed, with emissions greatest during the day, although lower emissions were present at night. None of the measured environmental parameters was a strong "universal" driver for fluxes, which were heterogeneous within and between the wetlands, and larger on average than reported to date; plant species appeared to be the dominant factor, the latter confirmed by vegetation removal experiments. Calluna vulgaris and Phragmites australis emitted particularly large amounts of CH3Br, the former also emitting substantial CH3Cl. While acknowledging the substantial uncertainties in extrapolating globally, observations from this work suggest that wetlands contribute more CH3Br and CH3Cl to the atmosphere than current World Meteorological Organization estimates.

  5. Recovery of bromine from methyl bromide using amorphous MnO{sub x} photocatalysts

    SciTech Connect

    Lin, Jung-Chou; Suib, S.L.; Cutlip, M.B.

    1996-07-01

    Amorphous MnO{sub x} (AMO) has been prepared by the reaction of potassium permanganate and oxalic acid. Surface area measurements and pore size distribution analyses show that AMO has high surface (200 m{sup 2}/g) area and a microporous structure. Kinetic results indicate that methyl bromide degradation using AMO photocatalysts is due to a combination of thermocatalytic and photocatalytic reactions; however, the photocatalytic reaction is predominant. Detailed studies show that both molecular oxygen and bulk lattice oxygen of AMO can be involved in the oxidation of methyl bromide to carbon dioxide. Kinetic data, Auger analyses, and FTIR spectra suggest that both oxidation state changes of Mn and the presence of bromide adsorbed on the surface might lead to deactivation of the catalyst. According to mass balance calculations and analyses with potassium iodide solutions with starch, the final products are bromine, carbon dioxide, and water. The overall reaction for methyl bromide degradation under illumination using AMO photocatalyst can be expressed as CH{sub 3}Br{sub (g)} + 7/4O{sub 2(g)} {yields} CO{sub 2(g)} + 3/2H{sub 2}O(g) + {1/2}Br{sub 2(g)}. 27 refs., 10 figs., 2 tabs.

  6. Methyl bromide as a building disinfectant: interaction with indoor materials and resulting byproduct formation.

    PubMed

    Corsi, Richard L; Walker, Matthew B; Liljestrand, Howard M; Hubbard, Heidi F; Poppendieck, Dustin G

    2007-05-01

    Several buildings were contaminated with Bacillus anthracis in the fall of 2001. These events required consideration of how to disinfect large indoor spaces for continued worker occupation. The interactions of gaseous disinfectants with indoor materials may inhibit the disinfection process, cause persistence of the disinfectant, and lead to possible byproduct formation and persistence. Methyl bromide (CH3Br) is a candidate for disinfection/deactivation of biological agents in buildings. In this study, 24 indoor materials were exposed to CH3Br for 16 hr at concentrations ranging from 100 to 2500 ppm in 48-L electropolished stainless steel chambers. CH3Br concentrations were measured during and after disinfection. Its interactions with materials were observed to be small, with nearly complete and rapid desorption. Between 3% and 8% of CH3Br adsorbed to four materials (office partition, ceiling tile, particle-board, and gypsum wallboard with satin paint), and the degree of adsorption decreased with increasing relative humidity. The percentage of adsorption to all other materials was <2%. This result suggests that when designing disinfection events with CH3Br, loss to indoor materials can be neglected in terms of disinfectant dose calculations. Possible reaction products were identified and/or quantified before and after exposure to CH3Br. Several monomethylated and dimethylated aliphatic compounds were observed in chamber air at low concentrations after the exposures of six materials to CH3Br. Concentration increases also occurred for chemicals that were observed to naturally off-gas from materials before exposure to CH3Br, suggesting that CH3Br may play a role in enhancing the natural off-gassing of chemicals, for example, by competitive displacement of compounds that already existed in the materials. The results described in this paper should facilitate the design of building disinfection systems involving CH3Br.

  7. Strain IMB-1, a novel bacterium for the removal of methyl bromide in fumigated agricultural soils

    USGS Publications Warehouse

    Connell, Hancock T.L.; Costello, A.M.; Lidstrom, M.E.; Oremland, R.S.

    1998-01-01

    A facultatively methylotrophic bacterium, strain IMB-1, that has been isolated from agricultural soil grows on methyl bromide (MeBr), methyl iodide, methyl chloride, and methylated amines, as well as on glucose, pyruvate, or acetate. Phylogenetic analysis of its 16S rRNA gene sequence indicates that strain IMB-1 classes in the alpha subgroup of the class Proteobacteria and is closely related to members of the genus Rhizobium. The ability of strain IMB-1 to oxidize MeBr to CO2 is constitutive in cells regardless of the growth substrate. Addition of cell suspensions of strain IMB-1 to soils greatly accelerates the oxidation of MeBr, as does pretreatment of soils with low concentrations of methyl iodide. These results suggest that soil treatment strategies can be devised whereby bacteria can effectively consume MeBr during field fumigations, which would diminish or eliminate the outward flux of MeBr to the atmosphere.

  8. Atmospheric chemistry of toxic contaminants 4. Saturated halogenated aliphatics: Methyl bromide, epichlorhydrin, phosgene

    SciTech Connect

    Grosjean, D. )

    1991-01-01

    Mechanisms are outlined for the reactions that contribute to in-situ formation and atmospheric removal of the saturated halogenated aliphatic contaminants methyl bromide, epichlorhydrin, and phosgene. In-situ formation is important only for phosgene and involves the reaction of OH with chloroethenes and other chlorinated hydrocarbons. A ranking of these phosgene precursors is given using data for precursor ambient concentrations and chemical reactivity. The three toxic compounds studied are long-lived in the atmosphere, where removal of phosgene and methyl bromide by chemical reactions is negligibly slow. Epichlorhydrin is removed slowly by reaction with OH, leading to formaldehyde, chloroacetaldehyde, and the chlorinated peroxyacyl nitrate CH{sub 2}ClC(O)OONO{sub 2}.

  9. Reactions of ground-state and electronically excited sodium atoms with methyl bromide and molecular chlorine

    SciTech Connect

    Weiss, P.S.; Mestdagh, J.M.; Schmidt, H.; Covinsky, M.H.; Lee, Y.T. )

    1991-04-18

    The reactions of ground- and excited-state Na atoms with methyl bromide (CH{sub 3}Br) and chlorine (Cl{sub 2}) have been studied by using the crossed molecular beams method. For both reactions, the cross sections increase with increasing electronic energy. The product recoil energies change little with increasing Na electronic energy, implying that the product internal energies increase substantially. For Na + CH{sub 3}Br, the steric angle of acceptance opens with increasing electronic energy.

  10. Anharmonic force fields from analytic second derivatives: Method and application to methyl bromide

    NASA Astrophysics Data System (ADS)

    Schneider, Winfried; Thiel, Walter

    1989-05-01

    An efficient finite difference procedure is described for calculating anharmonic normal-coordinate force constants from quantum-chemical analytic second derivatives. Displacements along normal coordinates are used to generate those cubic and quartic force constants which are needed in a second-order perturbation treatment of anharmonicity. The anharmonic force field of methyl bromide is predicted, and the calculated spectroscopic constants compared with experimental data.

  11. Prediction of methyl bromide flux from area sources using the ISCST model

    SciTech Connect

    Ross, L.J.; Johnson, B.; Kim, K.D.; Hsu, J.

    1996-07-01

    Growing concern about atmospheric exposure of humans to pesticides has led to increased air monitoring in California. Air monitoring data typically consist of measurements made downwind from point or area sources. The utility of monitoring at fixed stations is limited for establishing buffer zones to protect neighboring populations from pesticide exposure. A modeling approach designed to use these data would provide the flexibility needed to establish buffer zones. The Industrial Source Complex Short Term (ISCST) model is a gaussian plume dispersion model that predicts air concentrations around point or area sources using emission rates (flux) and meteorological conditions as model inputs. The flux data, however, are typically not collected in the field nor available in the literature. In order to use the field data currently available, we developed a procedure using methyl bromide (MeBr) concentrations around two area sources and the ISCST model, to back-calculate flux. In addition, MeBr flux was measured concurrently by cooperators conducting an independent study. Air concentrations, together with actual meteorological data, were used as inputs to the ISCST model. Flux of MeBr was then back-calculated using a two step process: (1) an arbitrary flux value of 100 {mu}g m{sup {minus}2} s{sup {minus}1} was used as an initial input value. Resultant air concentrations predicted by the model were then regressed on air concentrations predicted by the model were then regressed on air concentrations measured offsite and (2) the resultant regression coefficient was then used to adjust the arbitrary flux to a back-calculated flux. Using another regression analysis, back-calculated and measured flux rates were found to be significantly correlated, indicating this approach may be suitable for indirect estimation of flux. Implications for the use of this method in establishing buffer zones designed to protect human health are discussed. 14 refs., 5 figs., 1 tab.

  12. The suppression of opposed-jet methane-air flames by methyl bromide

    SciTech Connect

    Miller, E.; McMillion, L.G. )

    1992-04-01

    This paper reports on an opposed-jet diffusion flame burner that was used in conjunction with an emission infrared spectrometer to study the effects of the addition of methyl bromide on the combustion of methane with air. An optical system permitted incremental scanning of a laminar diffusion flame formed between two horizontally opposed burner tubes. The image of the flat flame was focused on an auxiliary slit of the spectrometer by optical mirrors and scanned by moving the slit passed the image. For a methane-air flame with an overall stoichiometric ratio, {phi}, of 0.86, the spectra for the 3700-2400 cm{sup {minus}1} region (H{sub 2}O, OH, CO{sub 2}, CH{sub 3}, and HCHO bands) and 2400 to 2000 cm{sup {minus}1} (CO and CO{sub 2} bands) were compared with the spectra obtained when methyl bromide was added to the air-side of the burner. Supplementary measurements were made on methane-air and methane-oxygen-nitrogen flames with {phi} values in the range of 0.74 - 2.0. In some cases, the methane was diluted with nitrogen, and the methyl bromide was added to either the fuel or the air side of the burner.

  13. Determination of methyl bromide in air resulting from pre-plant fumigations of plowed fields

    SciTech Connect

    Woodrow, J.E.; Honaganahalli, P.; Seiber, J.N.

    1995-12-31

    A method for measuring residues of methyl bromide in air entails concentrating the fumigant on charcoal from an airstream at a flowrate of 100 ml/min, desorption of the trapped material with benzyl alcohol solvent in a sealed vial at 60-110{degrees}C for 10-15 min, and then sampling of the equilibrated vapor for gas chromatographic assay using electron-capture detection. The desorbed vapor is chromatographed on a 27 in x 0.32 mm (id) porous-layer open tubular column, on which methyl bromide has a retention time of about 6 min at 90{degrees}C and at a carrier gas flowrate of 3-3.5 ml/min. Using this method, standard curves were linear over at least three orders of magnitude and a practical limit of detection for field air was about 20 ng/m{sup 3} ({approximately}5 ppt). This method has been used in studies concerned with methyl bromide volatilization from fumigated fields and with ambient background levels.

  14. A CHRONIC INHALATION STUDY OF METHYL BROMIDE TOXICITY IN B6C3F1 MICE. (FINAL REPORT TO THE NATIONAL TOXICOLOGY PROGRAM)

    SciTech Connect

    HABER, S.B.

    1987-06-26

    This report provides a detailed account of a two year chronic inhalation study of methyl bromide toxicity in B6C3Fl mice conducted for the National Toxicology Program. Mice were randomized into three dose groups (10, 33 and 100 ppm methyl bromide) and one control group (0 ppm) per sex and exposed 5 days/week, 6 hours/day, for a total of 103 weeks. Endpoints included body weight; clinical signs and mortality, and at 6, 15 and 24 months of exposure, animals were sacrificed for organ weights, hematology and histopathology. In addition, a subgroup of animals in each dosage group was monitored for neurobehavioral and neuropathological changes. After only 20 weeks of exposure, 48% of the males and 12% of the females in the 100 ppm group had died. Exposures were terminated in that group and the surviving mice were observed for the duration of the study. Exposure of B6C3Fl mice to methyl bromide, even for only 20 weeks, produced significant changes in growth rate, mortality, organ weights and neurobehavioral functioning. These changes occurred in both males and females, but were more pronounced in males.

  15. Improving food and agriculture productivity and the environment: Canadian initiatives in methyl bromide alternatives and emission control technologies. Revised edition

    SciTech Connect

    Marcotte, M.; Tibelius, C.

    1998-12-31

    Methyl bromide, a fumigant used in the agricultural sector, was listed as an ozone-depleting substance under the Montreal Protocol and is scheduled for phasing out in Canada. This report begins with a review of the joint industry/government approach being taken to plan and manage this phase-out. It then reviews alternative solutions that have been formulated and tested as replacements for the use of methyl bromide in greenhouse cultivation, soil fumigation, strawberry transplant production, tobacco production, grain production, and food processing facilities. Contact names and addresses are provided for those seeking further information. The final sections describe activities in methyl bromide recovery and recycling and list industry and government organizations that have expertise in methyl bromide alternatives.

  16. High-resolution slice imaging of quantum state-to-state photodissociation of methyl bromide

    SciTech Connect

    Lipciuc, M. Laura; Janssen, Maurice H. M.

    2007-12-14

    The photodissociation of rotationally state-selected methyl bromide is studied in the wavelength region between 213 and 235 nm using slice imaging. A hexapole state selector is used to focus a single (JK=11) rotational quantum state of the parent molecule, and a high speed slice imaging detector measures directly the three-dimensional recoil distribution of the methyl fragment. Experiments were performed on both normal (CH{sub 3}Br) and deuterated (CD{sub 3}Br) parent molecules. The velocity distribution of the methyl fragment shows a rich structure, especially for the CD{sub 3} photofragment, assigned to the formation of vibrationally excited methyl fragments in the {nu}{sub 1} and {nu}{sub 4} vibrational modes. The CH{sub 3} fragment formed with ground state Br({sup 2}P{sub 3/2}) is observed to be rotationally more excited, by some 230-340 cm{sup -1}, compared to the methyl fragment formed with spin-orbit excited Br({sup 2}P{sub 1/2}). Branching ratios and angular distributions are obtained for various methyl product states and they are observed to vary with photodissociation energy. The nonadiabatic transition probability for the {sup 3}Q{sub 0+}{yields}{sup 1}Q{sub 1} transition is calculated from the images and differences between the isotopes are observed. Comparison with previous non-state-selected experiments indicates an enhanced nonadiabatic transition probability for state-selected K=1 methyl bromide parent molecules. From the state-to-state photodissociation experiments the dissociationenergy for both isotopes was determined, D{sub 0}(CH{sub 3}Br)=23 400{+-}133 cm{sup -1} and D{sub 0}(CD{sub 3}Br)=23 827{+-}94 cm{sup -1}.

  17. Life without methyl bromide: the Italian experience in replacing the fumigant.

    PubMed

    Gullino, M L; Clini, C; Garibaldi, A

    2005-01-01

    Methyl bromide (MB) has been the most widely used chemical for the fumigation of soil, commodities, buildings and furniture for over seventy years. Since January 1st 2005, it has been phased-out in industrialized countries, where only critical uses are allowed, because of international regulatory measures designed to reduce substances that potentially deplete the stratospheric ozone layer. Italy ranked second in the world, after USA, in MB consumption, due to the importance of horticultural crop production. In order to replace the use of MB, research in Italy was aimed at: a) reducing the use of MB and its emission (short-term goal); b) developing alternative pest control methods, based on available technologies (mid-term goal); c) developing new MB alternatives (mid- and long-term goal). Italian growers switched to other fumigants, applied at reduced dosages, lowering their environmental impact and risk of worker exposure. Moreover, the adoption of non-chemical alternatives slowly but steadily increased as a result of the many activities (demonstration trials, seminars, etc.) carried out in the country. The gradual shift to MB alternatives over a 10 year period, as well as the use of half rates of MB under virtually impermeable plastic films (VIFs), has generally prevented the feared loss of competitiveness of Italian horticulture. Extension in cooperation with the fumigation companies was able to provide growers with a range of methods for soil disinfestation. The experience gained in Italy and how it can help developing countries to define strategies and training programmes needed to comply with the Montreal Protocol is discussed.

  18. Low-temperature methyl bromide fumigation of emerald ash borer (Coleoptera: Buprestidae) in ash logs.

    PubMed

    Barak, Alan V; Elder, Peggy; Fraser, Ivich

    2011-02-01

    Ash (Fraxinus spp.) logs, infested with fully developed, cold-acclimated larval and prepupal emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), were fumigated with methyl bromide (MeBr) at 4.4 and 10.0 degrees C for 24 h. Concentrations X time dosages of MeBr obtained were 1579 and 1273 g-h/m3 (24-h exposure) at 4.4 and 10.0 degrees C after applied doses of 112 and 96 g/m3, respectively. MeBr concentrations were simultaneously measured with a ContainIR infrared monitor and Fumiscope thermal conductivity meter calibrated for MeBr to measure the effect of CO2 on Fumiscope concentration readings compared with the infrared (IR) instrument. The presence of CO2 caused false high MeBr readings. With the thermal conductivity meter, CO2 measured 11.36 g/m3 MeBr per 1% CO2 in clean air, whereas the gas-specific infrared ContainIR instrument measured 9.55% CO2 as 4.2 g/m3 MeBr (0.44 g/m3 per 1% CO2). The IR instrument was 0.4% as sensitive to CO2 as the thermal conductivity meter. After aeration, fumigated and control logs were held for 8 wk to capture emerging beetles. No A. planipennis adults emerged from any of the fumigated logs, whereas 262 emerged from control logs (139 and 123/m2 at 4.4 and 10.0 degrees C, respectively). An effective fumigation dose and minimum periodic MeBr concentrations are proposed. The use of a CO2 scrubber in conjunction with nonspecific thermal conductivity instruments is necessary to more accurately measure MeBr concentrations.

  19. Description of Toluene Inhibition of Methyl Bromide Biodegradation in Seawater and Isolation of a Marine Toluene Oxidizer That Degrades Methyl Bromide

    PubMed Central

    Goodwin, Kelly D.; Tokarczyk, Ryszard; Stephens, F. Carol; Saltzman, Eric S.

    2005-01-01

    Methyl bromide (CH3Br) and methyl chloride (CH3Cl) are important precursors for destruction of stratospheric ozone, and oceanic uptake is an important component of the biogeochemical cycle of these methyl halides. In an effort to identify and characterize the organisms mediating halocarbon biodegradation, we surveyed the effect of potential cometabolic substrates on CH3Br biodegradation using a 13CH3Br incubation technique. Toluene (160 to 200 nM) clearly inhibited CH3Br and CH3Cl degradation in seawater samples from the North Atlantic, North Pacific, and Southern Oceans. Furthermore, a marine bacterium able to co-oxidize CH3Br while growing on toluene was isolated from subtropical Western Atlantic seawater. The bacterium, Oxy6, was also able to oxidize o-xylene and the xylene monooxygenase (XMO) pathway intermediate 3-methylcatechol. Patterns of substrate oxidation, lack of acetylene inhibition, and the inability of the toluene 4-monooxygenase (T4MO)-containing bacterium Pseudomonas mendocina KR1 to degrade CH3Br ruled out participation of the T4MO pathway in Oxy6. Oxy6 also oxidized a variety of toluene (TOL) pathway intermediates such as benzyl alcohol, benzylaldehyde, benzoate, and catechol, but the inability of Pseudomonas putida mt-2 to degrade CH3Br suggested that the TOL pathway might not be responsible for CH3Br biodegradation. Molecular phylogenetic analysis identified Oxy6 to be a member of the family Sphingomonadaceae related to species within the Porphyrobacter genus. Although some Sphingomonadaceae can degrade a variety of xenobiotic compounds, this appears to be the first report of CH3Br degradation for this class of organism. The widespread inhibitory effect of toluene on natural seawater samples and the metabolic capabilities of Oxy6 indicate a possible link between aromatic hydrocarbon utilization and the biogeochemical cycle of methyl halides. PMID:16000753

  20. Description of toluene inhibition of methyl bromide biodegradation in seawater and isolation of a marine toluene oxidizer that degrades methyl bromide.

    PubMed

    Goodwin, Kelly D; Tokarczyk, Ryszard; Stephens, F Carol; Saltzman, Eric S

    2005-07-01

    Methyl bromide (CH3Br) and methyl chloride (CH3Cl) are important precursors for destruction of stratospheric ozone, and oceanic uptake is an important component of the biogeochemical cycle of these methyl halides. In an effort to identify and characterize the organisms mediating halocarbon biodegradation, we surveyed the effect of potential cometabolic substrates on CH3Br biodegradation using a 13CH3Br incubation technique. Toluene (160 to 200 nM) clearly inhibited CH3Br and CH3Cl degradation in seawater samples from the North Atlantic, North Pacific, and Southern Oceans. Furthermore, a marine bacterium able to co-oxidize CH3Br while growing on toluene was isolated from subtropical Western Atlantic seawater. The bacterium, Oxy6, was also able to oxidize o-xylene and the xylene monooxygenase (XMO) pathway intermediate 3-methylcatechol. Patterns of substrate oxidation, lack of acetylene inhibition, and the inability of the toluene 4-monooxygenase (T4MO)-containing bacterium Pseudomonas mendocina KR1 to degrade CH3Br ruled out participation of the T4MO pathway in Oxy6. Oxy6 also oxidized a variety of toluene (TOL) pathway intermediates such as benzyl alcohol, benzylaldehyde, benzoate, and catechol, but the inability of Pseudomonas putida mt-2 to degrade CH3Br suggested that the TOL pathway might not be responsible for CH3Br biodegradation. Molecular phylogenetic analysis identified Oxy6 to be a member of the family Sphingomonadaceae related to species within the Porphyrobacter genus. Although some Sphingomonadaceae can degrade a variety of xenobiotic compounds, this appears to be the first report of CH3Br degradation for this class of organism. The widespread inhibitory effect of toluene on natural seawater samples and the metabolic capabilities of Oxy6 indicate a possible link between aromatic hydrocarbon utilization and the biogeochemical cycle of methyl halides. PMID:16000753

  1. Aerodynamic measurements of methyl bromide volatilization from tarped and nontarped fields

    USGS Publications Warehouse

    Majewski, M.S.; McChesney, M.M.; Woodrow, J.E.; Prueger, J.H.; Seiber, J.N.

    1995-01-01

    Methyl bromide (MeBr) is used extensively in agriculture as a soil fumigant and there is growing concern over the role it may play in the depletion of stratospheric ozone. Methyl bromide is applied using various techniques and very little is known about how much of the applied fumigant volatilizes into the atmosphere after the application. This held study was designed to estimate the post-application methyl bromide volatilization loss rates from two different application practices. The fields were approximately 6 km apart in Monterey County, California, and were treated in conformity with local practices as of 1992. The MeBr was injected at a depth of 25 to 30 cm. One field was covered simultaneously with a high-barrier plastic film tarp during the application, and the other was left uncovered, but the furrows made by the injection shanks were bedded over. Volatilization fluxes were estimated using an aerodynamic-gradient technique immediately following the completion of the application process and continued for 9 d for the tarped held and 6 d for the nontarped field. The cumulative volatilization losses from the tarped field were 22% of the nominal application within the first 5 d of the experiment and about 32% of the nominal application within 9 d including the one day after the tarp was removed on Day 8 after application. In contrast, the nontarped field lost 89% of the nominal application by volatilization in 5 d. The volatilization rate from the tarped field was shown to he significantly lower than the nontarped field at a 95% confidence level.

  2. Aerodynamic measurements of methyl bromide volatilization from tarped and nontarped fields

    SciTech Connect

    Majewski, M.S.; McChesney, M.M.; Woodrow, J.E.; Seiber, J.N.

    1995-07-01

    Methyl bromide (MeBr) is used extensively in agriculture as a soil fumigant and there is growing concern over the role it may play in the depletion of stratospheric ozone. Methyl bromide is applied using various techniques and very little is known about how much of the applied fumigant volatilizes into the atmosphere after the application. This field study was designed to estimate the post-application methyl bromide volatilization loss rates from two different application practices. The fields were approximately 6 km apart in Monterey County, California, and were treated in conformity with local practices as of 1992. The MeBr was injected at a depth of 25 to 30 cm. One field was covered simultaneously with a high-barrier plastic film tarp during the application, and the other was left uncovered, but the furrows made by the injection shanks were bedded over. Volatilization fluxes were estimated using an aerodynamic-gradient technique immediately following the completion of the application process and continued for 9 d for the tarped field and 6 d for the nontarped field. The cumulative volatilization losses from the tarped field were 22% of the nominal application within the first 5 d of the experiment and about 32% of the nominal application within 9 d including the one day after the tarp was removed on Day 8 after application. In contrast, the nontarped field lost 89% of the nominal application by volatilization in 5 d. The volatilization rate from the tarped field was shown to be significantly lower than the nontarped field at a 95% confidence level. 43 refs., 5 figs., 3 tabs.

  3. Supported nickel bromide catalyst for atom transfer radical polymerization (ATRP) of methyl methacrylate.

    PubMed

    Duquesne, E; Degée, Ph; Habimana, J; Dubois, Ph

    2004-03-21

    A new supported catalytic system, i.e. nickel bromide catalyst ligated by triphenylphosphine (TPP) ligands immobilized onto crosslinked polystyrene resins (PS-TPP) is reported. Per se, this catalyst does not allow any control over the polymerization of methyl methacrylate (MMA) initiated by ethyl 2-bromoisobutyrate but, in the presence of a given amount of purposely added free TPP, it promotes controlled ATRP of MMA. Indeed colorless PMMA chains of low polydispersity indices are readily recovered, the molecular weight of which linearly increases with monomer conversion and agrees with the expected values. Recycling of the supported catalyst is evidenced and does not prevent the polymerization from being controlled. PMID:15010758

  4. Crystal structure of 2-bromo-3-di-methyl-amino-N,N,N',N',4-penta-methyl-4-(tri-methyl-sil-yloxy)pent-2-eneamidinium bromide.

    PubMed

    Tiritiris, Ioannis; Kress, Ralf; Kantlehner, Willi

    2015-12-01

    The reaction of the ortho-amide 1,1,1-tris-(di-methyl-amino)-4-methyl-4-(tri-methyl-sil-yloxy)pent-2-yne with bromine in benzene, yields the title salt, C15H33BrN3OSi(+)·Br(-). The C-N bond lengths in the amidinium unit are 1.319 (6) and 1.333 (6) Å, indicating double-bond character, pointing towards charge delocalization within the NCN plane. The C-Br bond length of 1.926 (5) Å is characteristic for a C-Br single bond. Additionally, there is a bromine-bromine inter-action [3.229 (3) Å] present involving the anion and cation. In the crystal, weak C-H⋯Br inter-actions between the methyl H atoms of the cation and the bromide ions are present. PMID:26870498

  5. Tailoring acidity of HZSM-5 nanoparticles for methyl bromide dehydrobromination by Al and Mg incorporation

    PubMed Central

    2014-01-01

    Three kinds of HZSM-5 nanoparticles with different acidity were tailored by impregnating MgO or varying Si/Al ratios. Both the textural and acidic properties of the as-prepared nanoparticles were characterized by nitrogen adsorption-desorption measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM), ammonia temperature-programmed desorption (NH3-TPD) and Fourier transform infrared spectroscopy (FTIR or Py-FTIR). It was found that the intensity of Lewis acid sites with weak strength was enhanced by impregnating MgO or reducing Al concentration, and such an enhancement could be explained by the formation of Mg(OH)+ or charge unbalance of the MgO framework on the surface of HZSM-5 support. The effect of HZSM-5 nanoparticles' acidity on methyl bromide dehydrobromination as catalyst was evaluated. As the results, MgHZ-360 catalyst with the highest concentration of Lewis acid sites showed excellent stability, which maintained methyl bromide conversion of up 97% in a period of 400 h on stream. Coke characterization by BET measurements and TGA/DTA and GC/MS analysis revealed that polymethylated naphthalenes species were formed outside the channels of the catalyst with higher acid intensity and higher Brønsted acid concentration during the initial period of reaction, while graphitic carbon formed in the channels of catalyst with lower acid intensity and higher Lewis acid concentration during the stable stage. PMID:25328502

  6. Moving away from methyl bromide: political economy of pesticide transition for California strawberries since 2004.

    PubMed

    Mayfield, Erin N; Norman, Catherine Shelley

    2012-09-15

    We examine the progress of the phaseout of the use of the pesticide methyl bromide in the production of California field strawberries. This phaseout is required under the Montreal Protocol and has been contentious in this sector, which receives exemptions from the schedule initially agreed under the treaty, and in international negotiations over the future of the Protocol. We examine the various ex-ante predictions of the impacts on growers, consumers and trade patterns in light of several years of declining allocations under the Critical Use provisions of the Protocol and the 2010 approval of iodomethane for use in California and subsequent 2012 withdrawal of this alternative from the US market. We find that, contrary to ex-ante industry claims, the years of declining methyl bromide use have been years of rising yields, acreage, exports, revenues and market share for California growers, even when faced with a global recession and increased imports from Mexican growers who retain the right to use the chemical under the Protocol. This has implications for the Protocol as a whole and for the remainder of the US phaseout of this chemical in particular. PMID:22575205

  7. Postharvest treatment of fresh fruit from California with methyl bromide for control of light brown apple moth (Lepidoptera: Tortricidae).

    PubMed

    Walse, Spencer S; Myers, Scott W; Liu, Yong-Biao; Bellamy, David E; Obenland, David; Simmons, Greg S; Tebbets, Steve

    2013-06-01

    Methyl bromide (MB) chamber fumigations were evaluated for postharvest control of light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), in fresh fruit destined for export from California. To simulate external feeding, larvae were contained in gas-permeable cages and distributed throughout loads of peaches, plums, nectarines (all Prunus spp.), apples (Malus spp.), raspberries (Rubus spp.), or grapes (Vitis spp.). Varying the applied MB dose and the differential sorption of MB by the loads resulted in a range of exposures, expressed as concentration x time cross products (CTs) that were verified by gas-chromatographic quantification of MB in chamber headspace over the course of each fumigation. CTs > or = 60 and > or = 72 mg liter(-1) h at 10.0 +/- 0.5 and 15.6 +/- 0.5 degrees C (x +/- s, average +/- SD), respectively, yielded complete mortality of approximately 6,200 larvae at each temperature. These confirmatory fumigations corroborate E. postvittana mortality data for the first time in relation to measured MB exposures and collectively comprise the largest number of larval specimens tested to date. In addition, akinetic model of MB sorption was developed for the quarantine fumigation of fresh fruit based on the measurement of exposures and how they varied across the fumigation trials. The model describes how to manipulate the applied MB dose, the load factor, and the load geometry for different types of packaged fresh fruit so that the resultant exposure is adequate for insect control.

  8. Photochemistry of Methyl Bromide on the α-Cr2O3(0001) Surface

    SciTech Connect

    Henderson, Michael A.

    2010-09-30

    The photochemical properties of the Cr-terminated α-Cr2O3(0001) surface were explored using methyl bromide (CH3Br) as a probe molecule. CH3Br adsorbed and desorbed molecularly from the Cr-terminated α-Cr2O3(0001) surface without detectable thermal decomposition. Temperature programmed desorption (TPD) revealed a CH3Br desorption state at 240 K for coverages up to 0.5 ML, followed by more weakly bound molecules desorbing at 175 K for coverages up to 1 ML. Multilayer exposures led to desorption at ~130 K. The CH3Br sticking coefficient was unity at 105 K for coverages up to monolayer saturation, but decreased as the multilayer formed. In contrast, pre-oxidation of the surface (using an oxygen plasma source) led to capping of surface Cr3+ sites and near complete removal of CH3Br TPD states above 150 K. The photochemistry of chemisorbed CH3Br was explored on the Cr-terminated surface using post-irradiation TPD and photon stimulated desorption (PSD). Irradiation of adsorbed CH3Br with broad band light from a Hg arc lamp resulted in both photodesorption and photodecomposition of the parent molecule at a combined cross section of ~10-22 cm2. Parent PSD was indicative of molecular photodesorption, but CH3 was also detected in PSD and Br atoms were left on the surface, both reflective of photo-induced CH3-Br bond dissociation. Use of a 385 nm cut-off filter effectively shut down the photodissociation pathway but not the parent molecule photodesorption process. From these observations it is inferred that d-to-d transitions in α-Cr2O3, occurring at photon energies <3 eV, are not responsible for photodecomposition of 2 adsorbed CH3Br. It is unclear to what extent band-to-band versus direct CH3Br photolysis play in CH3-Br bond dissociation initiated by more energetic photons.

  9. Electroanalytical study of SYBR Green I and ethidium bromide intercalation in methylated and unmethylated amplicons.

    PubMed

    Ioannou, Andrea K; Alexiadou, Despina K; Kouidou, Sofia A; Voulgaropoulos, Anastasios N; Girousi, Stella Th

    2010-01-11

    This work involves the electrochemical study of the interaction of SYBR Green I (SG) with native DNA using differential pulse voltammetry at a carbon paste electrode (CPE) and alternating current voltammetry at a hanging mercury drop electrode (HMDE). At the CPE the peak current intensity at 1.0 V decreased by increasing the concentration of SG. At the HMDE, a decrease in the current intensity of the DNA peak at -1.2 V was also observed by increasing the concentration of SG. These results electrochemically confirmed that SG intercalates within the DNA double helix and changes its conformation. Through the present work the differentiation of differently methylated analytes was achieved by application of alternative current and differential pulse voltammetric techniques. Amplicons (PCR products) corresponding to the GC-rich p53 exon 5 containing cytosine and its methylated analogue, synthesized by substituting 60% of cytosine by 5-methyl-cytosine, were amplified and investigated electrochemically in the presence of SG and ethidium bromide (EtBr) by differential pulse voltammetry. Considerable peak current differences were observed in the presence of SG and EtBr for unmethylated exon 5 vs. methylated. Therefore, both SG and EtBr could serve as electrochemical probes for identifying different DNA conformations.

  10. Biological properties of sodium alkyl methyl ester sulfonate/alkyltrimethylammonium bromide surfactant mixtures.

    PubMed

    Wong, S P; Lim, W H; Cheng, S F; Chuah, C H

    2012-01-01

    Quaternary ammonium compounds (QACs) are commonly used as disinfectant in medical care, food industry, detergents and glue industries. This is due to a small concentration of QACs is sufficient to inhibit the growth of various bacteria strains. In this work, the inhibitive power of cationic surfactants, alkyltrimethylammonium bromide (C(n)TAB) in the presence of anionic surfactants, sodium alkyl methyl ester α-sulfonate (C(n)MES) was studied. The growth inhibition test with gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria were used to determine the toxicity of single and mixed surfactants. Results from this work showed that certain mixed surfactants have lower minimum inhibition concentration (MIC) as compared to the single C(n)TAB surfactants. Besides that, it was also found that alkyl chain length and the mixing ratios of the surfactants play a significant role in determining the mixture inhibitive power.

  11. Evaluation of containment and control options for methyl bromide in commodity treatment. Final report

    SciTech Connect

    DeWolf, G.B.; Harrison, M.R.

    1994-07-01

    Methyl bromide (MeBr), with the chemical formula CH3Br, also called bromomethane, is listed by the 1991 Montreal Protocol as an ozone depleting chemical similar to the other halogenated hydrocarbons such as the chloro-fluorocarbons (CFCs). The U.S. Environmental Protection Agency's (EPA's) regulations authorized by the Clean Air Act (CAA) call for a phaseout of MeBr by the year 2001. MeBr is widely used in United States agriculture as a fumigant. This study has gathered preliminary data that can be used to determine if some of the essential agricultural commodity fumigation applications for MeBr could be continued by the use of some emission control methods on those commodity fumigation applications.

  12. 78 FR 14508 - Notice of Affirmation of Addition of a Treatment Schedule for Methyl Bromide Fumigation of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-06

    ... Manual of the treatment described in the notice published at 77 FR 31564-31566 on May 29, 2012. FOR.... 305.3(b), we published a notice \\2\\ in the Federal Register on May 29, 2012 (77 FR 31564-31566, Docket... methyl bromide fumigation of cottonseed for the fungal plant pathogen Fusarium oxysporum f....

  13. Optimizing postharvest methyl bromide treatments to control spotted wing drosophila, Drosophila suzukii, in sweet cherries from Western USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide (MB) chamber fumigations were evaluated for postharvest control of spotted wing drosophila (SWD), Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), in fresh sweet cherry exports from Western USA. Sweet cherries were infested with SWD, incubated to maximize numbers of the most M...

  14. Aerosols and contact insecticides as alternatives to methyl bromide in flour mills, food production facilities, and food warehouses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fumigant methyl bromide (MB) is being phased out of production and usage to control stored product insects in flour and rice mills, as well as feed and food production plants, in the United States (US) and other developed countries throughout the world. A phase-out schedule has also been establi...

  15. Acute toxicity and responses of antioxidant systems to 1-methyl-3-octylimidazolium bromide at different developmental stages of goldfish.

    PubMed

    Li, Xiao-Yu; Zeng, Shi-Hu; Dong, Xiang-Yi; Ma, Jun-Guo; Wang, Jian-Ji

    2012-01-01

    Acute toxicity of 1-methyl-3-octylimidazolium bromide ([C(8)mim]Br) to goldfish at different developmental stages and responses of the antioxidant system in adult goldfish were evaluated in the present study. The results indicate that post-embryonic developmental toxicity of [C(8)mim]Br on goldfish is developmental-stage dependent. The juvenile and larva goldfish are more sensitive to [C(8)mim]Br-toxicity than the adult fish. Histological observations in adult goldfish reveal that acute [C(8)mim]Br exposure damages the hepatopancreas, intestines, and kidneys, indicating that these are possible target organs of [C(8)mim]Br toxicity in goldfish. Subsequent biochemical assays in adult goldfish show that [C(8)mim]Br also induces changes in the activities of the superoxide dismutase, catalase, glutathione peroxidase, and glutathione content of fish hepatopancreas. These results suggest that [C(8)mim]Br exposure may induce oxidant stress and lipid peroxidation in hepatopancreas of adult goldfish. In addition, we also find that [C(8)mim]Br causes a remarkable increase in malondialdehyde (MDA) levels in the hepatopancreas of adult goldfish, and thus we think that the MDA level change can be a biomarker of [C(8)mim]Br toxicity in goldfish. The present study indicates that ionic liquids can be a threat to the survival, growth, and development of the fish population once they are accidentally leaked into aquatic ecosystems.

  16. Cytotoxicity, oxidative stress, and apoptosis in HepG2 cells induced by ionic liquid 1-methyl-3-octylimidazolium bromide.

    PubMed

    Li, Xiaoyu; Ma, Junguo; Wang, Jianji

    2015-10-01

    The present study aimed to determine the cytotoxicity of 1-methyl-3-octylimidazolium bromide ([C8mim]Br) on the human hepatocellular carcinoma (HepG2) cells in order to elucidate the biochemical and molecular mechanism of [C8mim]Br-cytotoxicity. For this purpose, cell viability, oxidative stress, apoptosis, caspase activity, and apoptosis-related gene expression in HepG2 cells following [C8mim]Br-exposure were evaluated. The results showed that viability of HepG2 cells was decreased by [C8mim]Br-exposure in a concentration-dependent pattern. Moreover, biochemical assays reveal that [C8mim]Br-exposure can induce apoptosis, cause overproduction of reactive oxygen species (ROS), inhibit superoxide dismutase and catalase, reduce glutathione content, and increase the cellular malondialdehyde level of HepG2 cells. The transcriptions of p53 and bax were markedly up-regulated while bcl-2 was significantly down-regulated in HepG2 cells after [C8mim]Br-exposure, suggesting that p53 and bcl-2 family may be involved in the cytotoxicity and apoptosis of HepG2 cells caused by [C8mim]Br. In addition, we also found that caspase-3, caspase-8, and caspase-9 were significantly activated in HepG2 cells following [C8mim]Br-exposure. Our results suggest that ROS may be a key early signal of [C8mim]Br-induced apoptosis and caspases play a key role in the initiation and execution of apoptosis of HepG2 cells. PMID:26099465

  17. Evaluation of Methyl Bromide Alternatives Efficacy against Soil-Borne Pathogens, Nematodes and Soil Microbial Community

    PubMed Central

    Xie, Hongwei; Yan, Dongdong; Mao, Liangang; Wang, Qiuxia; Li, Yuan; Ouyang, Canbin; Guo, Meixia; Cao, Aocheng

    2015-01-01

    Methyl bromide (MB) and other alternatives were evaluated for suppression of Fusarium spp., Phytophthora spp., and Meloidogyne spp. and their influence on soil microbial communities. Both Fusarium spp. and Phytophthora spp. were significantly reduced by the MB (30.74 mg kg-1), methyl iodide (MI: 45.58 mg kg-1), metham sodium (MS: 53.92 mg kg-1) treatments. MS exhibited comparable effectiveness to MB in controlling Meloidogyne spp. and total nematodes, followed by MI at the tested rate. By contrast, sulfuryl fluoride (SF: 33.04 mg kg-1) and chloroform (CF: 23.68 mg kg-1) showed low efficacy in controlling Fusarium spp., Phytophthora spp., and Meloidogyne spp. MB, MI and MS significantly lowered the abundance of different microbial populations and microbial biomass in soil, whereas SF and CF had limited influence on them compared with the control. Diversity indices in Biolog studies decreased in response to fumigation, but no significant difference was found among treatments in PLFA studies. Principal component and cluster analyses of Biolog and PLFA data sets revealed that MB and MI treatments greatly influenced the soil microbial community functional and structural diversity compared with SF treatment. These results suggest that fumigants with high effectiveness in suppressing soil-borne disease could significantly influence soil microbial community. PMID:25723395

  18. Destruction of methyl bromide sorbed to activated carbon by thiosulfate or electrolysis.

    PubMed

    Yang, Yu; Li, Yuanqing; Walse, Spencer S; Mitch, William A

    2015-04-01

    Methyl bromide (CH3Br) is widely used as a fumigant for postharvest and quarantine applications for agricultural products at port facilities due to the short treatment period required, but it is vented from fumigation chambers to the atmosphere after its use. Due to the potential contributions of CH3Br to stratospheric ozone depletion, technologies for the capture and degradation of the CH3Br are needed to enable its continued use. Although granular activated carbon (GAC) has been used for CH3Br capture and thiosulfate has been used for destruction of CH3Br in aqueous solution, this research explored techniques for direct destruction of CH3Br sorbed to GAC. Submerging the GAC in an aqueous thiosulfate solution achieved debromination of CH3Br while sorbed to the GAC, but it required molar concentrations of thiosulfate because of the high CH3Br loading and produced substantial concentrations of methyl thiosulfate. Submergence of the GAC in water and use of the GAC as the cathode of an electrolysis unit also debrominated sorbed CH3Br. The reaction appeared to involve a one-electron transfer, producing methyl radicals that incorporated into the GAC. Destruction rates increased with decreasing applied voltage down to ∼-1.2 V vs the standard hydrogen electrode. Cycling experiments conducted at -0.77 V indicated that >80% debromination of CH3Br was achieved over ∼ 30 h with ∼ 100% Coulombic efficiency. Sorptive capacity and degradation efficiency were maintained over at least 3 cycles. Capture of CH3Br fumes from fumigation chambers onto GAC, and electrolytic destruction of the sorbed CH3Br could mitigate the negative impacts of CH3Br usage pending the development of suitable replacement fumigants. PMID:25789797

  19. Influence of soil fumigation by methyl bromide and methyl iodide on rhizosphere and phyllosphere microbial community structure.

    PubMed

    Ibekwe, A M; Papiernik, S K; Yang, C-H

    2010-07-01

    Rhizosphere and phyllosphere microbial communities were evaluated on roots and leaves of growth chamber-grown lettuce (Lactuca sativa (L.) cv. Green Forest) plants by culture-dependent and -independent methods after soil fumigation. Denaturing gradient gel electrophoresis (DGGE) with 16S rRNA primers followed by cloning and sequencing was used to identify major rRNA bands from the rhizosphere and phyllosphere. Three weeks after fumigation, there were no differences (P = 0.16) in rhizosphere microbial communities between the fumigated treatments and the control. The same effect was observed during week seven after fumigation (P=0.49). Also, no significant differences (P=0.49) were found in the phyllosphere microbial communities between the fumigated treatments and the control during the growth period of the plant. A majority of the bands in the rhizosphere were related to known bacterial sequences with a 96 to 100 % sequence similarity. Some of the derived sequences were related to Pseudomonas syringae pv. tomato DC300 and Bradyrhizobium japonicum USDA 110. A total of 23 isolates were identified from leaf surface by both culture-dependent and independent methods, and only Photorhabdus luminescens was found on leaf surface using both techniques. All the Biolog isolates from phyllosphere were from the Proteobacteria phylum compared to the culture-independent bands from the leaves that were from different bacterial phyla. Based on our data, methyl bromide (MeBr) and methyl iodide (MeI) did not have any significant negative effects on rhizosphere and phyllosphere microbial communities throughout the growing period of lettuce. PMID:20512733

  20. Modification of the surfaces of Wyoming montmorillonite by the cationic surfactants alkyl trimethyl, dialkyl dimethyl, and trialkyl methyl ammonium bromides.

    PubMed

    Xi, Yunfei; Frost, Ray L; He, Hongping

    2007-01-01

    Surfaces of a Wyoming SWy-2 sodium montmorillonite were modified using microwave radiation through intercalation with the cationic surfactants octadecyl-trimethyl ammonium bromide, dimethyldioctadecylammonium bromide, and methyl-tri-octadecyl ammonium bromide by an ion exchange mechanism. Changes in the surfaces and structure were characterized using X-ray diffraction (XRD), thermal analysis (TG) and infrared (IR) spectroscopy. Different configurations of surfactants within montmorillonite interlayer are proposed based on d(001) basal spacings. A range of surfactant molecular environments within the surface-modified montmorillonite are proposed based upon their thermal decomposition. IR spectroscopy using a smart endurance single bounce diamond attenuated total reflection (ATR) cell has been used to study the changes in the spectra of CH asymmetric and symmetric stretching modes of the surfactants to provide more information of the surfactant molecular configurations.

  1. Degradation of methyl bromide by methanotrophic bacteria in cell suspensions and soils

    USGS Publications Warehouse

    Oremland, R.S.; Miller, L.G.; Culbertson, C.W.; Connell, T.L.; Jahnke, L.

    1994-01-01

    Cell suspensions of Methylococcus capsulatus mineralized methyl bromide (MeBr), as evidenced by its removal from the gas phase, the quantitative recovery of Br- in the spent medium, and the production of 14CO2 from [14C]MeBr. Methyl fluoride (MeF) inhibited oxidation of methane as well as that of [14C]MeBr. The rate of MeBr consumption by cells varied inversely with the supply of methane, which suggested a competitive relationship between these two substrates. However, MeBr did not support growth of the methanotroph. In soils exposed to high levels (10,000 ppm) of MeBr, methane oxidation was completely inhibited. At this concentration, MeBr removal rates were equivalent in killed and live controls, which indicated a chemical rather than biological removal reaction. At lower concentrations (1,000 ppm) of MeBr, methanotrophs were active and MeBr consumption rates were 10-fold higher in live controls than in killed controls. Soils exposed to trace levels (10 ppm) of MeBr demonstrated complete consumption within 5 h of incubation, while controls inhibited with MeF or incubated without O2 had 50% lower removal rates. Aerobic soils oxidized [14C]MeBr to 14CO2, and MeF inhibited oxidation by 72%. Field experiments demonstrated slightly lower MeBr removal rates in chambers containing MeF than in chambers lacking MeF. Collectively, these results show that soil methanotrophic bacteria, as well as other microbes, can degrade MeBr present in the environment.

  2. Degradation of methyl bromide by methanotrophic bacteria in cell suspensions and soils.

    PubMed Central

    Oremland, R S; Miller, L G; Culbertson, C W; Connell, T L; Jahnke, L

    1994-01-01

    Cell suspensions of Methylococcus capsulatus mineralized methyl bromide (MeBr), as evidence by its removal from the gas phase, the quantitative recovery of Br- in the spent medium, and the production of 14CO2 from [14C]MeBr. Methyl fluoride fluoride (MeF) inhibited oxidation of methane as well as that of [14C]MeBr. The rate of MeBr consumption by cells varied inversely with the supply of methane, which suggested a competitive relationship between these two substrates. However, MeBr did not support growth of the methanotroph. In soils exposed to high levels (10,000 ppm) of MeBr, methane oxidation was completely inhibited. At this concentration, MeBr removal rates were equivalent in killed and live controls, which indicated a chemical rather than biological removal reaction. At lower concentration (1,000 ppm) of MeBr, methanotrophs were active and MeBr consumption rates were 10-fold higher in live controls than in killed controls. Soils exposed to trace levels (10 ppm) of MeBr demonstrated complete consumption within 5 h of incubation, while controls inhibited with MeF or incubated without O2 had 50% lower removal rates. Aerobic soils oxidized [14C]MeBr to 14CO2, and MeF inhibited oxidation by 72%. Field experiments demonstrated slightly lower MeBr removal rates in chambers containing MeF than in chambers lacking MeF. Collectively, these results show that soil methanotrophic bacteria, as well as other microbes, can degrade MeBr present in the environment. PMID:7986039

  3. The Challenge of Research and Extension to Define and Implement Alternatives to Methyl Bromide

    PubMed Central

    Noling, J. W.; Becker, J. O.

    1994-01-01

    Over the past 30 years, methyl bromide (MBr), a broad spectrum fumigant, has been used extensively for soilborne disease and pest control in the production of many fruit, vegetable, turf, and nursery crops. Recently, agricultural emissions of MBr were implicated as a potentially significant contributor to stratospheric ozone depletion. As a precautionary measure for global ozone protection, the U.S. Environmental Protection Agency has enforced federal legislation which mandates a complete phase-out of MBr use within the United States by 1 January 2001. Thus, new cost effective, environmentally compatible strategies for control of nematodes and other soilborne pests and pathogens must be developed and tested in a relatively short time to avoid significant losses in crop productivity. The extent to which certain agricultural industries that are now heavily reliant on MBr are affected will depend on the development of sustainable, integrated tactics to pest control, such as combinations of cultural, chemical, and biological tactics. New muhidisciplinary research and extension programs must be developed to address and overcome major constraints and incompatibilities that have prevented such tactics from being widely adopted. PMID:19279928

  4. A Comprehensive Theoretical Investigation of the Molecular Properties of Methyl Bromide (CH3Br)

    NASA Astrophysics Data System (ADS)

    Yu, Ang-Yang; Efil, Kürşat; Yang, Rui; Hu, Qing-Miao

    2015-12-01

    The properties of the ground and the lowest excited state of methyl bromide (CH3Br) have been studied with and without inclusion of the solvent effects in this work. The geometric parameters, energies, and frequencies of the ground state and the triplet state are calculated by using the MP2(full)/6-311++G** level of theory. The vertical excitation for the singlet state is also investigated. It is found that the theoretical results performed by the TDDFT/B3P86/6-311++G** method are in the best agreement with the experimental results. In addition, the dissociation energy of CH3Br molecule is computed at MP2(full)/6-311++G** level of theory for the gas phase and in water. The ionisation potential (IP), electron affinity (EA), electronegativity (χ), electrophilicity index (ω), hardness (η), softness (S), and chemical potential (μ) values are calculated from HOMO-LUMO energies both in the gas phase and in solvent (water). These theoretical results could serve as a guide for future experimental investigations.

  5. Methyl bromide emissions from a covered field: III. Correcting chamber flux for temperature

    SciTech Connect

    Yates, S.R.; Gan, J.; Ernst, F.F.; Wang, D.

    1996-07-01

    An experiment was conducted to investigate the environmental fate and transport of methyl bromide (MeBr) in agricultural systems. Part of this experiment involved the use of three flow-through chambers to estimate the MeBr flux through a sheet of clear polyethylene plastic covering the field. Using the chamber data, the total mass lost to the atmosphere was estimated to be 96% of the applied mass, and the results were highly variable between chambers (i.e., standard deviation of 298 kg or 35%). The air temperature inside the chamber was found to be much higher than the air temperature outside and was highly correlated with the diurnal variation in incoming solar radiation. Since the diffusion through polyethylene film was found to be strongly dependent on the temperature, a method was developed to correct the chamber flux density data for enhanced diffusion caused by increases in the temperature inside the chamber. After correcting for temperature, the estimated total MeBr emission was reduced to approximately 59% (21% standard deviation) of the applied amount, which is about 5% less than was measured using other methods. When chambers are used to measure volatilization of MeBr or other fumigants from fields covered with a sheet of polyethylene plastic, the chambers should be designed to minimize internal heating or some method should be used to correct the volatilization rate for the effects of temperature. 16 refs., 5 figs., 1 tab.

  6. Laboratory-scale measurements and simulations of effect of application methods on soil methyl bromide emission

    SciTech Connect

    Gan, J.; Yates, S.R.; Spencer, W.F.

    1997-01-01

    Methyl bromide (bromomethane, MeBr), which originates from the oceans, fumigation, and a few other sources, is reportedly contributing to the ozone depletion in the stratosphere. Due to the heavy reliance on this fumigant in the production of many crops, it is of particular importance to accurately quantify the atmospheric input of MeBr arising from agricultural uses, and develop feasible measures to minimize these emissions. In this study, we determined the effect of two important application variables, surface tarp and injection depth, on MeBr transport and transformation in the soil and its emission from the soil surface under controlled conditions. Following 20- and 30-cm injections, covering the soil surface with 1-mil (0.025 mm) high-density polyethylene film resulted in an average of 48% reduction in MeBr emission. Increasing the injection depth from 20 to 60 cm caused a decrease in MeBr emission of 54% under untarped conditions and 40% under tarped conditions. The influence of application methods on MeBr atmospheric emissions should be considered when estimating the contribution of agricultural fumigation to the overall atmospheric MeBr burden on a global scale. The results also indicate that MeBr emission after soil fumigation may be substantially minimized by using surface tarpaulins and deep injections. 34 refs., 5 figs., 1 tab.

  7. An investigation of the atmospheric sources and sinks of Methyl Bromide

    NASA Technical Reports Server (NTRS)

    Singh, Hanwant B.; Kanakidou, M.

    1993-01-01

    Methyl Bromide (CH3Br) is a ubiquitous component of the atmosphere and has been implicated as an important player in the depletion of stratospheric ozone. Atmospheric CH3Br abundances, interhemispheric gradients, oceanic concentrations, man-made emissions, and removal processes have been analyzed and interpreted with the help of a simple box model and a 2D global photochemical model. Its calculated atmospheric lifetime (T) of 1.7-1.9 years, based on reaction with OH radicals, is consistent with a global source of 90-110 Gg (10 exp 9 g)/year. Consequences of a much shorter lifetime of 1.2 years, due to possible deposition/hydrolysis losses, are also considered. Available data are used to estimate a CH3Br source that is 35 percent (20-50 percent) man-made and 65 percent (80-50 percent) natural. Oceans are substantially supersaturated and provide the most important natural source of about 60 (40-80) Gg/year.

  8. Stable bromine isotopic composition of methyl bromide released from plant matter

    NASA Astrophysics Data System (ADS)

    Horst, Axel; Holmstrand, Henry; Andersson, Per; Thornton, Brett F.; Wishkerman, Asher; Keppler, Frank; Gustafsson, Örjan

    2014-01-01

    Methyl bromide (CH3Br) emitted from plants constitutes a natural source of bromine to the atmosphere, and is a component in the currently unbalanced global CH3Br budget. In the stratosphere, CH3Br contributes to ozone loss processes. Studies of stable isotope composition may reduce uncertainties in the atmospheric CH3Br budget, but require well-constrained isotope fingerprints of the source end members. Here we report the first measurements of stable bromine isotopes (δ81Br) in CH3Br from abiotic plant emissions. Incubations of both KBr-fortified pectin, a ubiquitous cell-stabilizing macromolecule, and of a natural halophyte (Salicornia fruticosa), yielded an enrichment factor (ε) of -2.00 ± 0.23‰ (1σ, n = 8) for pectin and -1.82 ± 0.02‰ (1σ, n = 4) for Salicornia (the relative amount of the heavier 81Br was decreased in CH3Br compared to the substrate salt). For short incubations, and up to 10% consumption of the salt substrate, this isotope effect was similar for temperatures from 30 up to 300 °C. For longer incubations of up to 90 h at 180 °C the δ81Br values increased from -2‰ to 0‰ for pectin and to -1‰ for Salicornia. These δ81Br source signatures of CH3Br formation from plant matter combine with similar data for carbon isotopes to facilitate multidimensional isotope diagnostics of the CH3Br budget.

  9. Methyl bromide as a quarantine treatment for Chlorophorus annularis (Coleoptera: Cerambycidae) in raw bamboo poles.

    PubMed

    Barak, Alan V; Weidong, Yang; Daojian, Yu; Yi, Jiao; Lin, Kang; Zhilin, Chen; Xingyuan, Ling; Guoping, Zhan

    2009-06-01

    At least 26 different species of insects of quarantine significance were intercepted from 1985 to 2005 on bamboo (Bambusa spp.) garden stakes from China. Three fifths of the live insects were cerambycids in nine genera, including Chlorophorus annularis F., the bamboo borer. The current APHIS-PPQ treatment is fumigation schedule T404-d, which requires high doses of methyl bromide (MeBr) for 24 h. No specific fumigation data exist for C. annularis. Chinese and American quarantine scientists cooperated in testing to determine whether this schedule, or lower doses, would be effective as a quarantine treatment for C. annularis infesting dried bamboo poles. A lower dose based on APHIS tests for solid wood packing (SWP) failed (3/511 survivors) at 56 g/m3 for 24 h at 10.0 degrees C. We therefore tested five progressive doses at five temperatures intermediate between the lower SWP schedule and the much higher applied doses (e.g., 120 g/m3 for 24 h at 10.0 degrees C) of schedule T404-d. Fumigations of infested bamboo poles conducted in 403.2-liter chambers with 52% vol:vol loading at doses of 48, 64, 80, 96, and 112 g/m3 at 26.7, 21.1, 15.6, 10.0, and 4.4 degrees C, respectively (20 total replicates, with 4 replicates per dose), had no survivors among 2,847 larvae, 140 pupae, and 122 adults. Control replicates (three) had a total of 455 live stages (397 larvae, 31 pupae, and 27 adults). Tests conducted with a sea/land cargo container loaded to 80% capacity with bamboo poles verified the ability of the schedule to maintain effective concentrations over 24 h in commercial-sized fumigations. We propose a new bamboo quarantine treatment schedule at reduced rates of applied MeBr. PMID:19610402

  10. Soil treatment with hot air (Cultivit) as alternative to methyl bromide.

    PubMed

    Runia, W T; Molendijk, L P G; Neophytou, G; Greenberger, A

    2006-01-01

    A new development in physical soil treatment is the application of hot air. Hot air treatment is based on blowing extremely hot air into rotavating humid soil. The method has been developed and applied commercially in Israel for the last few years. An increased growth response (IGR) was observed in several crops like potato, cauliflower, kohlrabi and the flower Esclepia, when the soil was treated with hot air prior to planting. Scientific trials were performed in Israel and Cyprus to quantify IGR and to evaluate the efficacy against plant-parasitic nematodes. Squash was grown in tunnels on root-knot nematodes (Meloidogyne javanica and M. incognita) infested fields in sandy (Israel) and clay loam (Cyprus) soils. In Israel hot air treatment was compared with metam sodium and methyl bromide and a cold air treated control. In Cyprus hot air treatment was compared with untreated control. Hot air treatment increased squash yield in Israel with 90 % and in Cyprus with 150%. Root assessments showed that after hot air treatment the root-knot nematodes were still able to infest plants and cause galling damage. Nematode counts were not reduced by hot air treatment. It may be concluded that the general concept of soil disinfestation is not applicable to hot air treatment. Any positive effect in yield could not be explained by reduction in nematode populations in soil. Possible chemical and biological changes in the hot air treated soils need to be identified. Further research will determine the possibilities and limitations of this method in other crops and under various climatic conditions.

  11. Manganese uptake and distribution in the brain after methyl bromide-induced lesions in the olfactory epithelia.

    PubMed

    Thompson, Khristy J; Molina, Ramon M; Donaghey, Thomas; Savaliya, Sandeep; Schwob, James E; Brain, Joseph D

    2011-03-01

    Manganese (Mn) is an essential nutrient with potential neurotoxic effects. Mn deposited in the nose is apparently transported to the brain through anterograde axonal transport, bypassing the blood-brain barrier. However, the role of the olfactory epithelial cells in Mn transport from the nasal cavity to the blood and brain is not well understood. We utilized the methyl bromide (MeBr) lesion model wherein the olfactory epithelium fully regenerates in a time-dependent and cell type-specific manner over the course of 6-8 weeks postinjury. We instilled (54)MnCl(2) intranasally at different recovery periods to study the role of specific olfactory epithelial cell types in Mn transport. (54)MnCl(2) was instilled at 2, 4, 7, 21, and 56 days post-MeBr treatment. (54)Mn concentrations in the blood were measured over the first 4-h period and in the brain and other tissues at 7 days postinstillation. Age-matched control rats were similarly studied at 2 and 56 days. Blood and tissue (54)Mn levels were reduced initially but returned to control values by day 7 post-MeBr exposure, coinciding with the reestablishment of sustentacular cells. Brain (54)Mn levels also decreased but returned to control levels only by 21 days, the period near the completion of neuronal regeneration/bulbar reinnervation. Our data show that Mn transport to the blood and brain temporally correlated with olfactory epithelial regeneration post-MeBr injury. We conclude that (1) sustentacular cells are necessary for Mn transport to the blood and (2) intact axonal projections are required for Mn transport from the nasal cavity to the olfactory bulb and brain.

  12. An estimation of the global emission of methyl bromide from rapeseed ( Brassica napus) from 1961 to 2003

    NASA Astrophysics Data System (ADS)

    Mead, M. Iqbal; White, Iain R.; Nickless, Graham; Wang, Kuo-Ying; Shallcross, Dudley E.

    Gan et al. [Gan, J., Yates, S.R., Ohr, H.D., Sims, J.J., 1998. Production of methyl bromide by terrestrial higher plants. Geophysical Research Letters 25 (19), 3595-3598] have reported that plants of the family Brassicaceae take up bromide from soils and subsequently release methyl bromide (CH 3Br) to the atmosphere deriving a significant emission from this source of about 7 Gg(10 9 g) yr -1. In this study, we determine a yearly global emission rate for CH 3Br from one such species, rapeseed, from 1961 to 2003 using data on crop harvest index and growth rate in conjunction with global production data. This study suggests that CH 3Br emissions from rapeseed have increased 10-fold from 1961 to 2003 and by a factor of 3-4 since 1980. It also suggests that the geographical distribution of emissions has also changed substantially in the last 40 yr. The annual emission of CH 3Br from mustard and cabbage is also estimated; whilst relative levels emitted from these species are less significant, as these crops are continually exploited for new applications CH 3Br emissions are set to increase.

  13. Methyl bromide emission from fields partially covered with a high-density polyethylene and a virtually impermeable film

    SciTech Connect

    Wang, D.; Yates, S.R.

    1998-09-01

    Recent field studies in the interior valley of southern California have indicated that 56--73% of methyl bromide (MeBr) used in soil fumigation is lost to atmospheric emission when the fields are covered completely with a high-density polyethylene (HDPE) film. The emission can be reduced to less than 5% when a virtually impermeable film or Hytibar is used to cover the fields. This study was conducted to determine MeBr emission from bedded field plots where only the beds were covered with a HDPE or a virtually impermeable plastic film. The results provide an assessment on MeBr emission from field beds partially covered with the HDPE film and the suitability of using a virtually impermeable film for emission reduction. Methyl bromide gas was applied to replicated field beds covered with either a HDPE or the Hytibar film. The films were removed 6 days after MeBr application. Replicated soil cores were taken from different locations of the field beds, 20 days after MeBr application, for the determination of soil bromide ion concentrations. The total amount of MeBr degraded from each plot was calculated from the measured bromide ion concentrations, and the potential emission was determined as the difference between the amount of applied and that of degraded. Results indicated that the potential emission from this bedded system was about 95% for the HDPE treatment and 90% for the Hytibar-covered plots. Regardless of the small improvement with the virtually impermeable film, the experiment clearly indicates that partially covering the field with either a HDPE or a virtually impermeable film would result in unacceptably high emission losses.

  14. Rapid Consumption of Low Concentrations of Methyl Bromide by Soil Bacteria

    PubMed

    Hines; Crill; Varner; Talbot; Shorter; Kolb; Harriss

    1998-05-01

    A dynamic dilution system for producing low mixing ratios of methyl bromide (MeBr) and a sensitive analytical technique were used to study the uptake of MeBr by various soils. MeBr was removed within minutes from vials incubated with soils and ~10 parts per billion by volume of MeBr. Killed controls did not consume MeBr, and a mixture of the broad-spectrum antibiotics chloramphenicol and tetracycline inhibited MeBr uptake by 98%, indicating that all of the uptake of MeBr was biological and by bacteria. Temperature optima for MeBr uptake suggested a biological sink, yet soil moisture and temperature optima varied for different soils, implying that MeBr consumption activity by soil bacteria is diverse. The eucaryotic antibiotic cycloheximide had no effect on MeBr uptake, indicating that soil fungi were not involved in MeBr removal. MeBr consumption did not occur anaerobically. A dynamic flowthrough vial system was used to incubate soils at MeBr mixing ratios as low as those found in the remote atmosphere (5 to 15 parts per trillion by volume [pptv]). Soils consumed MeBr at all mixing ratios tested. Temperate forest and grassy lawn soils consumed MeBr most rapidly (rate constant [k] = 0.5 min-1), yet sandy temperate, boreal, and tropical forest soils also readily consumed MeBr. Amendments of CH4 up to 5% had no effect on MeBr uptake even at CH4:MeBr ratios of 10(7), and depth profiles of MeBr and CH4 consumption exhibited very different vertical rate optima, suggesting that methanotrophic bacteria, like those presently in culture, do not utilize MeBr when it is at atmospheric mixing ratios. Data acquired with gas flux chambers in the field demonstrated the very rapid in situ consumption of MeBr by soils. Uptake of MeBr at mixing ratios found in the remote atmosphere occurs via aerobic bacterial activity, displays first-order kinetics at mixing ratios from 5 pptv to ~1 part per million per volume, and is rapid enough to account for 25% of the global annual loss of

  15. Critical use of methyl bromide for soil disinfestation in Belgium during 2005.

    PubMed

    Viaene, N; Eloot, B; De Vis, R; Decadt, R; Vergote, N; Bleyaert, P; Peeters, L; Trybou, M; Heungens, K

    2006-01-01

    During 2005, Belgium enforced a strict procedure for the assignment of critical-use permits for methyl bromide (MeBr) as a soil disinfestant. This procedure involved an inspection of the site before disinfestation by a representative of a registered institute, and a mandatory demonstration of the presence of a pest or disease for which a critical use permit could be granted according to the Critical Use Nominations (CUNs). The procedure was subject to random inspections by an independent institute. The results of these inspections demonstrated proper and timely evaluation of the permit requests. A total of 113 requests for a MeBr disinfestation permit were submitted in 2005. Out of these, 105 referred to applications in 2005. The remaining 8 requests referred to applications in 2006 and were denied a permit based on the lack of MeBr quotum granted to Belgium for 2006. Of the 105 requests for applications in 2005, 93 received a MeBr application permit for soil disinfestation. These 93 permits represented 15911 kg or 37.3% of the total quotum assigned to Belgium in 2005 (42676 kg). Most of the quotum was used for butterhead lettuce (11456 kg or 72% of the applied MeBr). For most commodities, a surplus in quotum was available. However, for chrysanthemum, the amount requested for critical use exceeded the available quotum. The most important pests and diseases for which a permit was assigned were Meloidogyne, Sclerotinia, Rhizoctonia, Olpidium, Pythium, Pyrenochaeta, Verticillium, and a combination of these fungi and nematodes. The 12 requests for which no permit was granted represented 2010 kg or 11.3% of the total amount requested. In addition, institutes carrying out the assignment procedure reported at least 62 extra cases where they had been contacted by a grower but where no official permit request was filed based on the first inspection. When including those cases, the total reduction of the potentially used amount of MeBr is about 44 %. When adding an estimated

  16. Atmospheric methyl bromide (CH{sub 3}Br) from agricultural soil fumigations

    SciTech Connect

    Yagi, K.; Williams, J.; Wang, N.Y.; Cicerone, R.J.

    1995-03-31

    The treatment of agricultural soils with CH{sub 3}Br (MeBr) has been suggested to be a significant source of atmospheric MeBr which is involved in stratospheric ozone loss. A field fumigation experiment showed that, after 7 days, 34 percent of the applied MeBr had escaped into the atmosphere. The remaining 66 percent should have caused an increase in bromide in the soil; soil bromide increased by an amount equal to 70 percent of the applied MeBr, consistent with the flux measurements to within 4 percent. Comparison with an earlier experiment in which the escape of MeBr to the atmosphere was greater showed that higher soil pH, organic content and soil moisture, and deeper, more uniform injection of MeBr may in combination reduce the escape of MeBr. 17 refs., 3 figs., 1 tab.

  17. 77 FR 31564 - Notice of Availability of a Treatment Evaluation Document; Methyl Bromide Fumigation of Cottonseed

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-29

    ... Federal Register on April 6, 2012 (77 FR 20752-20756), EPA proposed to reinstate the tolerance of methyl... Animal and Plant Health Inspection Service Notice of Availability of a Treatment Evaluation Document... add to the Plant Protection and Quarantine Treatment Manual a treatment schedule for methyl...

  18. Evaluation of the combination of dimethyl disulfide and dazomet as an efficient methyl bromide alternative for cucumber production in China.

    PubMed

    Mao, Liangang; Yan, Dongdong; Wang, Qiuxia; Li, Yuan; Ouyang, Canbin; Liu, Pengfei; Shen, Jin; Guo, Meixia; Cao, Aocheng

    2014-05-28

    The combination of dimethyl disulfide (DMDS) and dazomet (DZ) is a potential alternative to methyl bromide (MB) for soil disinfestation. The efficacy of DMDS plus DZ in controlling key soilborne pests was evaluated in a laboratory study and in two commercial cucumber greenhouses. Laboratory studies found that all of the combinations had positive synergistic effects on root-knot nematodes, two key soilborne fungi, and two major weed seeds. Greenhouse trials revealed that the combination of DMDS and DZ (30 + 25 g m(-2)) successfully suppressed Meloidogyne spp. root galling, sharply reduced the colony-forming units of Fusarium spp. and Phytophthora spp. on media, maintained high cucumber yields, and was not significantly different from MB or DMDS alone, but better than DZ alone. All of the chemical treatments provided significantly better results than the nontreated control. The results indicate that the combination of DMDS and DZ is an efficient MB alternative for cucumber production. PMID:24820184

  19. Activated carbons from end-products of tree nut and tree fruit production as sorbents for removing methyl bromide in ventilation effluent from postharvest chamber fumigation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    End-products of tree nuts and tree fruits grown in California, USA were evaluated for the ability to remove methyl bromide from the ventilation effluent of postharvest chamber fumigations. Activated carbon sorbents from walnut and almond shells as well as peach and prune pits were prepared using dif...

  20. Postharvest treatment of fresh fruit from California with methyl bromide for postharvest control of light brown apple moth, Epiphyas postvittana (Walker)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide chamber fumigations were evaluated for postharvest control of light brown apple moth (LBAM), Epiphyas postvittana (Walker), in fresh fruit exports. To simulate external feeding, larvae were contained in gas-permeable cages and distributed throughout loads of peaches, plums, nectarines...

  1. PERENNIAL CROP NURSERIES TREATED WITH METHYL BROMIDE AND ALTERNATIVE FUMIGANTS: EFFECTS ON WEED SEED VIABILITY, WEED DENSITIES, AND TIME REQUIRED FOR HAND WEEDING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weed control provided by alternative fumigants to methyl bromide (MeBr) needs to be tested in perennial crop nurseries in California because MeBr is being phased out in accordance with the Montreal Protocol, few herbicides are registered for perennial nursery use, and costs of other control measures...

  2. Development of an activated carbon-based electrode for the capture and rapid electrolytic reductive debromination of methyl bromide from post-harvest fumigations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Due to concerns surrounding its ozone depletion potential, there is a need for technologies to capture and destroy methyl bromide (CH3Br) emissions from post-harvest fumigations applied to control agricultural pests. Previously we described a system in which CH3Br fumes vented from fumigation chambe...

  3. One-pot preparation of trifluoromethylated homoallylic N-acylhydrazines or α-methylene-γ-lactams from acylhydrazines, trifluoroacetaldehyde methyl hemiacetal, allyl bromide and tin.

    PubMed

    Du, Ganggang; Huang, Danfeng; Wang, Ke-Hu; Chen, Xiaowei; Xu, Yanli; Ma, Junyan; Su, Yingpeng; Fu, Ying; Hu, Yulai

    2016-01-28

    An efficient and convenient one-pot method for the preparation of trifluoromethylated homoallylic N-acylhydrazines or α-methylene-γ-lactams has been described. In this process, allyl bromide and metal tin are used instead of toxic stannanes, and commercially available aqueous trifluoroacetaldehyde methyl hemiacetal was used as a trifluoromethyl source.

  4. Persistent modification of Nav1.9 following chronic exposure to insecticides and pyridostigmine bromide.

    PubMed

    Nutter, Thomas J; Cooper, Brian Y

    2014-06-15

    Many veterans of the 1991 Gulf War (GW) returned from that conflict with a widespread chronic pain affecting deep tissues. Recently, we have shown that a 60day exposure to the insecticides permethrin, chlorpyrifos, and pyridostigmine bromide (NTPB) had little influence on nociceptor action potential forming Nav1.8, but increased Kv7 mediated inhibitory currents 8weeks after treatment. Using the same exposure regimen, we used whole cell patch methods to examine whether the influences of NTPB could be observed on Nav1.9 expressed in muscle and vascular nociceptors. During a 60day exposure to NTPB, rats exhibited lowered muscle pain thresholds and increased rest periods, but these measures subsequently returned to normal levels. Eight and 12weeks after treatments ceased, DRG neurons were excised from the sensory ganglia. Whole cell patch studies revealed little change in voltage dependent activation and deactivation of Nav1.9, but significant increases in the amplitude of Nav1.9 were observed 8weeks after exposure. Cellular studies, at the 8week delay, revealed that NTPB also significantly prolonged action potential duration and afterhyperpolarization (22°C). Acute application of permethrin (10μM) also increased the amplitude of Nav1.9 in skin, muscle and vascular nociceptors. In conclusion, chronic exposure to Gulf War agents produced long term changes in the amplitude of Nav1.9 expressed in muscle and vascular nociceptors. The reported increases in Kv7 amplitude may have been an adaptive response to increased Nav1.9, and effectively suppressed behavioral pain measures in the post treatment period. Factors that alter the balance between Nav1.9 and Kv7 could release spontaneous discharge and produce chronic deep tissue pain. PMID:24732443

  5. Methyl Bromide alternatives for vegetable production in Georgia: On-farm trials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three fumigant alternatives, methyl iodide plus chloropicirn (MIDAS), dimethyl disulfide plus chloropicrin (DMDS), and Telone II plus chloropicrin plus Vapam (3-Way) have exhibited promising results in small plot trials for the control of pests (weeds, pathogens, nematodes) in plasticulture producti...

  6. 1,3-Diallyl-2-methyl­benzimidazolium bromide dihydrate

    PubMed Central

    Ennajih, Hamid; Bouhfid, Rachid; Zouihri, Hafid; Essassi, El Mokhtar; Ng, Seik Weng

    2009-01-01

    The bonds in the five-membered ring of the title hydrated salt, C14H17N2 +·Br−·2H2O, are delocalized. The cation lies on a special position of m site symmetry such that the mirror plane passes through the imidazol­yl–methyl bond and is perpendicular to the plane of the cation. The anion lies on another special position of 2 site symmetry. The anion and uncoordinated water mol­ecule are linked into a chain by O—H⋯O hydrogen bonds. One of the water O atoms is disordered over two sites of equal occupancy. PMID:21577792

  7. Degradation of methyl bromide and methyl chloride in soil microcosms: Use of stable C isotope fractionation and stable isotope probing to identify reactions and the responsible microorganisms

    NASA Astrophysics Data System (ADS)

    Miller, Laurence G.; Warner, Karen L.; Baesman, Shaun M.; Oremland, Ronald S.; McDonald, Ian R.; Radajewski, Stefan; Murrell, J. Colin

    2004-08-01

    Bacteria in soil microcosm experiments oxidized elevated levels of methyl chloride (MeCl) and methyl bromide (MeBr), the former compound more rapidly than the latter. MeBr was also removed by chemical reactions while MeCl was not. Chemical degradation dominated the early removal of MeBr and accounted for more than half of its total loss. Fractionation of stable carbon isotopes during chemical degradation of MeBr resulted in a kinetic isotope effect (KIE) of 59 ± 7‰. Soil bacterial oxidation dominated the later removal of MeBr and MeCl and was characterized by different KIEs for each compound. The KIE for MeBr oxidation was 69 ± 9‰ and the KIE for MeCl oxidation was 49 ± 3‰. Stable isotope probing revealed that different populations of soil bacteria assimilated added 13C-labeled MeBr and MeCl. The identity of the active MeBr and MeCl degrading bacteria in soil was determined by analysis of 16S rRNA gene sequences amplified from 13C-DNA fractions, which identified a number of sequences from organisms not previously thought to be involved in methyl halide degradation. These included Burkholderia, the major clone type in the 13C-MeBr fraction, and Rhodobacter, Lysobacter and Nocardioides the major clone types in the 13C-MeCl fraction. None of the 16S rRNA gene sequences for methyl halide oxidizing bacteria currently in culture (including Aminobacter strain IMB-1 isolated from fumigated soil) were identified. Functional gene clone types closely related to Aminobacter spp. were identified in libraries containing the sequences for the cmuA gene, which codes for the enzyme known to catalyze the initial step in the oxidation of MeBr and MeCl. The cmuA gene was limited to members of the alpha-Proteobacteria whereas the greater diversity demonstrated by the 16S rRNA gene may indicate that other enzymes catalyze methyl halide oxidation in different groups of bacteria.

  8. Degradation of methyl bromide and methyl chloride in soil microcosms: Use of stable C isotope fractionation and stable isotope probing to identify reactions and the responsible microorganisms

    USGS Publications Warehouse

    Miller, L.G.; Warner, K.L.; Baesman, S.M.; Oremland, R.S.; McDonald, I.R.; Radajewski, S.; Murrell, J.C.

    2004-01-01

    Bacteria in soil microcosm experiments oxidized elevated levels of methyl chloride (MeCl) and methyl bromide (MeBr), the former compound more rapidly than the latter. MeBr was also removed by chemical reactions while MeCl was not. Chemical degradation dominated the early removal of MeBr and accounted for more than half of its total loss. Fractionation of stable carbon isotopes during chemical degradation of MeBr resulted in a kinetic isotope effect (KIE) of 59 ?? 7???. Soil bacterial oxidation dominated the later removal of MeBr and MeCl and was characterized by different KIEs for each compound. The KIE for MeBr oxidation was 69 ?? 9??? and the KIE for MeCl oxidation was 49 ?? 3???. Stable isotope probing revealed that different populations of soil bacteria assimilated added 13C-labeled MeBr and MeCl. The identity of the active MeBr and MeCl degrading bacteria in soil was determined by analysis of 16S rRNA gene sequences amplified from 13C-DNA fractions, which identified a number of sequences from organisms not previously thought to be involved in methyl halide degradation. These included Burkholderia , the major clone type in the 13C-MeBr fraction, and Rhodobacter, Lysobacter and Nocardioides the major clone types in the 13C-MeCl fraction. None of the 16S rRNA gene sequences for methyl halide oxidizing bacteria currently in culture (including Aminobacter strain IMB-1 isolated from fumigated soil) were identified. Functional gene clone types closely related to Aminobacter spp. were identified in libraries containing the sequences for the cmuA gene, which codes for the enzyme known to catalyze the initial step in the oxidation of MeBr and MeCl. The cmuA gene was limited to members of the alpha-Proteobacteria whereas the greater diversity demonstrated by the 16S rRNA gene may indicate that other enzymes catalyze methyl halide oxidation in different groups of bacteria. Copyright ?? 2004 Elsevier Ltd.

  9. Evaluation of the Efficacy of Methyl Bromide in the Decontamination of Building and Interior Materials Contaminated with Bacillus anthracis Spores.

    PubMed

    Wood, Joseph P; Wendling, Morgan; Richter, William; Lastivka, Andrew; Mickelsen, Leroy

    2016-04-01

    The primary goal of this study was to determine the conditions required for the effective inactivation of Bacillus anthracis spores on materials by using methyl bromide (MeBr) gas. Another objective was to obtain comparative decontamination efficacy data with three avirulent microorganisms to assess their potential for use as surrogates for B. anthracis Ames. Decontamination tests were conducted with spores of B. anthracis Ames and Geobacillus stearothermophilus, B. anthracis NNR1Δ1, and B. anthracis Sterne inoculated onto six different materials. Experimental variables included temperature, relative humidity (RH), MeBr concentration, and contact time. MeBr was found to be an effective decontaminant under a number of conditions. This study highlights the important role that RH has when fumigation is performed with MeBr. There were no tests in which a ≥6-log10 reduction (LR) of B. anthracis Ames was achieved on all materials when fumigation was done at 45% RH. At 75% RH, an increase in the temperature, the MeBr concentration, or contact time generally improved the efficacy of fumigation with MeBr. This study provides new information for the effective use of MeBr at temperatures and RH levels lower than those that have been recommended previously. The study also provides data to assist with the selection of an avirulent surrogate for B. anthracis Ames spores when additional tests with MeBr are conducted. PMID:26801580

  10. Evaluation of the Efficacy of Methyl Bromide in the Decontamination of Building and Interior Materials Contaminated with Bacillus anthracis Spores

    PubMed Central

    Wendling, Morgan; Richter, William; Lastivka, Andrew; Mickelsen, Leroy

    2016-01-01

    The primary goal of this study was to determine the conditions required for the effective inactivation of Bacillus anthracis spores on materials by using methyl bromide (MeBr) gas. Another objective was to obtain comparative decontamination efficacy data with three avirulent microorganisms to assess their potential for use as surrogates for B. anthracis Ames. Decontamination tests were conducted with spores of B. anthracis Ames and Geobacillus stearothermophilus, B. anthracis NNR1Δ1, and B. anthracis Sterne inoculated onto six different materials. Experimental variables included temperature, relative humidity (RH), MeBr concentration, and contact time. MeBr was found to be an effective decontaminant under a number of conditions. This study highlights the important role that RH has when fumigation is performed with MeBr. There were no tests in which a ≥6-log10 reduction (LR) of B. anthracis Ames was achieved on all materials when fumigation was done at 45% RH. At 75% RH, an increase in the temperature, the MeBr concentration, or contact time generally improved the efficacy of fumigation with MeBr. This study provides new information for the effective use of MeBr at temperatures and RH levels lower than those that have been recommended previously. The study also provides data to assist with the selection of an avirulent surrogate for B. anthracis Ames spores when additional tests with MeBr are conducted. PMID:26801580

  11. Potential impacts of imposing methyl bromide phaseout on US strawberry growers: a case study of a nomination for a critical use exemption under the Montreal Protocol.

    PubMed

    Norman, Catherine S

    2005-04-01

    The Montreal Protocol on Substances that Deplete the Ozone Layer requires developed countries to phaseout methyl bromide production and non-quarantine uses by 2005 and developing countries to do the same by 2015. Exemptions to phaseout have been significant in slowing the process of abatement; many countries have applied for exemptions for some uses, partly on grounds that phaseout is economically infeasible. Data on the US strawberry market are used to investigate grower costs arising from substitution away from methyl bromide, the impact of trends in and characteristics of the demand for fresh strawberries, and characteristics of trade with countries not yet required to eliminate use of the compound. It appears that actual net costs to growers will be much smaller than the simple increase in production costs cited in the US nomination for exemption.

  12. Bacterial oxidation of dibromomethane and methyl bromide in natural waters and enrichment cultures

    USGS Publications Warehouse

    Goodwin, K.D.; Schaefer, J.K.; Oremland, R.S.

    1998-01-01

    Bacterial oxidation of 14CH2Br2 and 14CH3Br was measured in freshwater, estuarine, seawater, and hypersaline-alkaline samples. In general, bacteria from the various sites oxidized similar amounts of 14CH2Br2 and comparatively less 14CH3Br. Bacterial oxidation of 14CH3Br was rapid in freshwater samples compared to bacterial oxidation of 14CH3Br in more saline waters. Freshwater was also the only site in which methyl fluoride-sensitive bacteria (e.g., methanotrophs or nitrifiers) governed brominated methane oxidation. Half-life calculations indicated that bacterial oxidation of CH2Br2 was potentially significant in all of the waters tested. In contrast, only in freshwater was bacterial oxidation of CH3Br as fast as chemical removal. The values calculated for more saline sites suggested that bacterial oxidation of CH3Br was relatively slow compared to chemical and physical loss mechanisms. However, enrichment cultures demonstrated that bacteria in seawater can rapidly oxidize brominated methanes. Two distinct cultures of nonmethanotrophic methylotrophs were recovered; one of these cultures was able to utilize CH2Br2 as a sole carbon source, and the other was able to utilize CH3Br as a sole carbon source.

  13. Identification of Methyl Halide-Utilizing Genes in the Methyl Bromide-Utilizing Bacterial Strain IMB-1 Suggests a High Degree of Conservation of Methyl Halide-Specific Genes in Gram-Negative Bacteria

    USGS Publications Warehouse

    Woodall, C.A.; Warner, K.L.; Oremland, R.S.; Murrell, J.C.; McDonald, I.R.

    2001-01-01

    Strain IMB-1, an aerobic methylotrophic member of the alpha subgroup of the Proteobacteria, can grow with methyl bromide as a sole carbon and energy source. A single cmu gene cluster was identified in IMB-1 that contained six open reading frames: cmuC, cmuA, orf146, paaE, hutI, and partial metF. CmuA from IMB-1 has high sequence homology to the methyltransferase CmuA from Methylobacterium chloromethanicum and Hyphomicrobium chloromethanicum and contains a C-terminal corrinoid-binding motif and an N-terminal methyl-transferase motif. However, cmuB, identified in M. chloromethanicum and H. chloromethanicum, was not detected in IMB-1.

  14. A study of the photodissociation physics of methyl bromide on gallium arsenide(110)

    SciTech Connect

    Schwarz, W.N.

    1992-01-01

    A study of the effects of laser light at various wavelengths, from UV (193 nm) to IR (860 nm), on the reaction of a well characterized ordered GaAs (110) surface with physisorbed CH[sub 3]Br is described. The adsorption of CH[sub 3]Br on the surface is found to be molecular. The amount of coverage is determined by a calibration of exposure versus number of monolayers. Information about the dynamics is obtained by the use of pulsed laser light of 20 ns pulse width combined with time-of-flight (TOF) measurements. The TOF spectra show five distinct features: (1) A direct dissociation peak is observed with UV light of 193 and 248 nm wavelength on samples with coverages >1 ML. For coverages <1 ML this channel is quenched due to resonant electron tunneling. (2) The peak initiated by DEA of hot electrons is fixed in energy at 1.1 eV, independent of the wavelength of the incident light, and has a threshold slightly below 351 nm. This peak is only detectable for coverages >1 ML. (3) The DEA feature due to thermalized electrons appears at different energies for 1 and 2 ML coverage. These energies are not sensitive to the wavelength of the incident laser light, and are located at 0.6 eV for 1 ML and at 0.25 eV for 2 ML. The threshold for this process coincides with the fundamental band gap of GaAs. Both peaks decays as a function of irradiation exposure. The DEA reaction product Br[sup [minus

  15. Dissociation of internal energy-selected methyl bromide ion revealed from threshold photoelectron-photoion coincidence velocity imaging

    NASA Astrophysics Data System (ADS)

    Tang, Xiaofeng; Zhou, Xiaoguo; Sun, Zhongfa; Liu, Shilin; Liu, Fuyi; Sheng, Liusi; Yan, Bing

    2014-01-01

    Dissociative photoionization of methyl bromide (CH3Br) in an excitation energy range of 10.45-16.90 eV has been investigated by using threshold photoelectron-photoion coincidence (TPEPICO) velocity imaging. The coincident time-of-flight mass spectra indicate that the ground state X2E of CH3Br+ is stable, and both A2A1 and B2E ionic excited states are fully dissociative to produce the unique fragment ion of CH3+. From TPEPICO 3D time-sliced velocity images of CH3+ dissociated from specific state-selected CH3Br+ ion, kinetic energy release distribution (KERD) and angular distribution of CH3+ fragment ion are directly obtained. Both spin-orbit states of Br(2P) atom can be clearly observed in fast dissociation of CH3Br+(A2A1) ion along C-Br rupture, while a KERD of Maxwell-Boltzmann profile is obtained in dissociation of CH3Br+(B2E) ion. With the aid of the re-calculated potential energy curves of CH3Br+ including spin-orbit coupling, dissociation mechanisms of CH3Br+ ion in A2A1 and B2E states along C-Br rupture are revealed. For CH3Br+(A2A1) ion, the CH3+ + Br(2P1/2) channel is occurred via an adiabatic dissociation by vibration, while the Br(2P3/2) formation is through vibronic coupling to the high vibrational level of X2E state followed by rapid dissociation. C-Br bond breaking of CH3Br+(B2E) ion can occur via slow internal conversion to the excited vibrational level of the lower electronic states and then dissociation.

  16. Laboratory production of bromoform, methylene bromide, and methyl iodide by macroalgae and distribution in nearshore southern California waters

    SciTech Connect

    Manley, S.L. ); Goodwin, K.; North, W.J. )

    1992-12-01

    Production rates of bromoform (CHBr[sub 3]), methylene bromide (CH[sub 2]Br[sub 2]), and methyl iodide (CH[sub 3]I) were measured in the laboratory for 11 species of marine macroalgae. Production rates of the volatile bromomethanes extrapolated to a global scale suggest that marine macroalgae produce 2 [times] 10[sup 11] g Br yr[sup [minus]1] (1 [times] 10[sup 9] mol Br yr[sup [minus]1]), 98% of which is bromoform. Laminarians (kelps) produce 61% of this organic Br. These calculations suggest that marine macroalgae are important in the biogeochemical cycling of Br. Seawater concentrations of CHBr[sub 3], CH[sub 2]Br[sub 2], and CH[sub 3]I were determined from various southern California coastal locales. High concentrations were measured in seawater from the canopy and the bottom of a dense bed of Macrocystis as compared to other sites. Surface seawater concentrations of these halomethanes showed a strong cross-shore gradient with the highest concentration in the kelp canopy and the lowest at 5 km offshore. Seawater adjacent to decaying macroalgae on the bottom of a submarine canyon was not enriched in halomethanes relative to surface water. Water exiting a productive estuary was enriched only with CH[sub 2]Br[sub 2], although two algal species that are abundant there (Ulva and Enteromorpha) showed high laboratory production rates of both CHBr[sub 3] and CH[sub 2]Br[sub 2]. 21 refs., 2 figs., 2 tabs.

  17. Consumption of Tropospheric Levels of Methyl Bromide by C1 Compound-Utilizing Bacteria and Comparison to Saturation Kinetics

    USGS Publications Warehouse

    Goodwin, K.D.; Varner, R.K.; Crill, P.M.; Oremland, R.S.

    2001-01-01

    Pure cultures of methylotrophs and methanotrophs are known to oxidize methyl bromide (MeBr); however, their ability to oxidize tropospheric concentrations (parts per trillion by volume [pptv]) has not been tested. Methylotrophs and methanotrophs were able to consume MeBr provided at levels that mimicked the tropospheric mixing ratio of MeBr (12 pptv) at equilibrium with surface waters (???2 pM). Kinetic investigations using picomolar concentrations of MeBr in a continuously stirred tank reactor (CSTR) were performed using strain IMB-1 and Leisingeria methylohalidivorans strain MB2T - terrestrial and marine methylotrophs capable of halorespiration. First-order uptake of MeBr with no indication of threshold was observed for both strains. Strain MB2T displayed saturation kinetics in batch experiments using micromolar MeBr concentrations, with an apparent Ks of 2.4 ??M MeBr and a Vmax of 1.6 nmol h-1 (106 cells)-1. Apparent first-order degradation rate constants measured with the CSTR were consistent with kinetic parameters determined in batch experiments, which used 35- to 1 ?? 107-fold-higher MeBr concentrations. Ruegeria algicola (a phylogenetic relative of strain MB2T), the common heterotrophs Escherichia coli and Bacillus pumilus, and a toluene oxidizer, Pseudomonas mendocina KR1, were also tested. These bacteria showed no significant consumption of 12 pptv MeBr; thus, the ability to consume ambient mixing ratios of MeBr was limited to C1 compound-oxidizing bacteria in this study. Aerobic C1 bacteria may provide model organisms for the biological oxidation of tropospheric MeBr in soils and waters.

  18. Are one or two dangerous? Methyl salicylate exposure in toddlers.

    PubMed

    Davis, Jonathan E

    2007-01-01

    Serious toxicity can result from exposure to small amounts of methyl salicylate. Methyl salicylate is widely available as a component in many over-the-counter brands of creams, ointments, lotions, liniments and medicated oils intended for topical application to relieve musculoskeletal aches and pains. Among the most potent forms of methyl salicylate is oil of wintergreen (98% methyl salicylate). Other products with varying concentrations of methyl salicylate are ubiquitous throughout many parts of the world, including a number of products marketed as Asian herbal remedies. The toxic potential of all of these formulations is often underestimated by health care providers and the general public. A comprehensive review of the existing medical literature on methyl salicylate poisoning was performed, and data compiled over the past two decades by the American Association of Poison Control Centers (AAPCC) was examined. Methyl salicylate continues to be a relatively common source of pediatric exposures. Persistent reports of life-threatening and fatal toxicity were found. In children less than 6 years of age, a teaspoon (5 mL) or less of oil of wintergreen has been implicated in several well-documented deaths. More needs to be done to educate both health care providers and the general public regarding the dangers of these widely available formulations.

  19. Dissociation of internal energy-selected methyl bromide ion revealed from threshold photoelectron-photoion coincidence velocity imaging

    SciTech Connect

    Tang, Xiaofeng; Zhou, Xiaoguo E-mail: yanbing@jlu.edu.cn; Liu, Shilin; Sun, Zhongfa; Liu, Fuyi; Sheng, Liusi; Yan, Bing E-mail: yanbing@jlu.edu.cn

    2014-01-28

    Dissociative photoionization of methyl bromide (CH{sub 3}Br) in an excitation energy range of 10.45–16.90 eV has been investigated by using threshold photoelectron-photoion coincidence (TPEPICO) velocity imaging. The coincident time-of-flight mass spectra indicate that the ground state X{sup 2}E of CH{sub 3}Br{sup +} is stable, and both A{sup 2}A{sub 1} and B{sup 2}E ionic excited states are fully dissociative to produce the unique fragment ion of CH{sub 3}{sup +}. From TPEPICO 3D time-sliced velocity images of CH{sub 3}{sup +} dissociated from specific state-selected CH{sub 3}Br{sup +} ion, kinetic energy release distribution (KERD) and angular distribution of CH{sub 3}{sup +} fragment ion are directly obtained. Both spin-orbit states of Br({sup 2}P) atom can be clearly observed in fast dissociation of CH{sub 3}Br{sup +}(A{sup 2}A{sub 1}) ion along C–Br rupture, while a KERD of Maxwell-Boltzmann profile is obtained in dissociation of CH{sub 3}Br{sup +}(B{sup 2}E) ion. With the aid of the re-calculated potential energy curves of CH{sub 3}Br{sup +} including spin-orbit coupling, dissociation mechanisms of CH{sub 3}Br{sup +} ion in A{sup 2}A{sub 1} and B{sup 2}E states along C–Br rupture are revealed. For CH{sub 3}Br{sup +}(A{sup 2}A{sub 1}) ion, the CH{sub 3}{sup +} + Br({sup 2}P{sub 1/2}) channel is occurred via an adiabatic dissociation by vibration, while the Br({sup 2}P{sub 3/2}) formation is through vibronic coupling to the high vibrational level of X{sup 2}E state followed by rapid dissociation. C–Br bond breaking of CH{sub 3}Br{sup +}(B{sup 2}E) ion can occur via slow internal conversion to the excited vibrational level of the lower electronic states and then dissociation.

  20. Evaluation of weather conditions for methyl bromide ambient air monitoring in Monterey, Santa Cruz, and Kern Counties in the year 2000.

    PubMed

    Li, LinYing; Johnson, Bruce; Segawa, Randy

    2006-01-01

    Weather condition is one of the most important factors affecting spatial and temporal distributions of air pollutants, especially for short-term air dispersion. Abnormal weather conditions might lead to higher or lower ambient air concentrations than they would be under normal weather conditions. Therefore, testing for normality of weather conditions during the air monitoring period is an essential step for evaluating ambient air monitoring results. In this paper, a distance method was used to select a most representative weather station from the available candidates. An array of meteorological elements were identified that affect air dispersion and transportation. A statistical method was used to determine whether the weather conditions during the air monitoring period were significantly different from that of previous years. Using methyl bromide ambient air monitoring as a case study, this paper documents the methods, procedures, and results of weather analysis for Monterey, Santa Cruz, and Kern Counties during ambient air monitoring periods for methyl bromide in the year 2000. With a few exceptions, the meteorological elements and atmospheric stability factors, such as wind speeds, wind directions, and stability classes, during the monitoring period were in the normal range. Although there were higher frequencies of stable atmospheric conditions in Monterey/Santa Cruz Counties than in Kern County, weather conditions during the monitoring period were not significantly different from normal local weather conditions of previous years. Consequently, the subchronic air concentrations observed during the ambient air monitoring periods for methyl bromide in the year 2000 was taken under typical weather conditions of those areas at that time of the year. PMID:16499148

  1. DNA methylation: conducting the orchestra from exposure to phenotype?

    PubMed

    Leenen, Fleur A D; Muller, Claude P; Turner, Jonathan D

    2016-01-01

    DNA methylation, through 5-methyl- and 5-hydroxymethylcytosine (5mC and 5hmC), is considered to be one of the principal interfaces between the genome and our environment, and it helps explain phenotypic variations in human populations. Initial reports of large differences in methylation level in genomic regulatory regions, coupled with clear gene expression data in both imprinted genes and malignant diseases, provided easily dissected molecular mechanisms for switching genes on or off. However, a more subtle process is becoming evident, where small (<10 %) changes to intermediate methylation levels are associated with complex disease phenotypes. This has resulted in two clear methylation paradigms. The latter "subtle change" paradigm is rapidly becoming the epigenetic hallmark of complex disease phenotypes, although we are currently hampered by a lack of data addressing the true biological significance and meaning of these small differences. Our initial expectation of rapidly identifying mechanisms linking environmental exposure to a disease phenotype led to numerous observational/association studies being performed. Although this expectation remains unmet, there is now a growing body of literature on specific genes, suggesting wide ranging transcriptional and translational consequences of such subtle methylation changes. Data from the glucocorticoid receptor (NR3C1) has shown that a complex interplay between DNA methylation, extensive 5'UTR splicing, and microvariability gives rise to the overall level and relative distribution of total and N-terminal protein isoforms generated. Additionally, the presence of multiple AUG translation initiation codons throughout the complete, processed mRNA enables translation variability, hereby enhancing the translational isoforms and the resulting protein isoform diversity, providing a clear link between small changes in DNA methylation and significant changes in protein isoforms and cellular locations. Methylation changes in

  2. Synthesis of tetraaza bromide macrocyclic and studies of its effect on poly(methyl methacrylate) grafted natural rubber (MG49) - lithium tertrafluoroborate (LiBF4) films

    NASA Astrophysics Data System (ADS)

    Mariam, Siti Nor; Yamin, Bohari M.; Ahmad, Azizan

    2013-11-01

    Good Poly(Methyl Methacrylate) Grafted natural Rubber (MG49) films with homogeneous and smooth surface were obtained in the presence of Lithium Tertrafluoroborate (LiBF4) and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-dienium bromide, (Me6N4H4)Br2 as dopants. The conductivity was found to be 3.63×10-6 S/cm an increase by seven fold compare to the undoped MG49.

  3. Synthesis of tetraaza bromide macrocyclic and studies of its effect on poly(methyl methacrylate) grafted natural rubber (MG49) - lithium tertrafluoroborate (LiBF{sub 4}) films

    SciTech Connect

    Mariam, Siti Nor; Yamin, Bohari M.; Ahmad, Azizan

    2013-11-27

    Good Poly(Methyl Methacrylate) Grafted natural Rubber (MG49) films with homogeneous and smooth surface were obtained in the presence of Lithium Tertrafluoroborate (LiBF{sub 4}) and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-dienium bromide, (Me{sub 6}N{sub 4}H{sub 4})Br{sub 2} as dopants. The conductivity was found to be 3.63×10{sup −6} S/cm an increase by seven fold compare to the undoped MG49.

  4. Arsenic exposure and DNA methylation among elderly men

    PubMed Central

    Lambrou, Angeliki; Baccarelli, Andrea; Wright, Robert O.; Weisskopf, Marc; Bollati, Valentina; Amarasiriwardena, Chitra; Vokonas, Pantel; Schwartz, Joel

    2012-01-01

    BACKGROUND Arsenic exposure has been linked to epigenetic modifications such as DNA methylation in in vitro and animal studies. This association has also been explored in highly exposed human populations, but studies among populations environmentally exposed to low arsenic levels are lacking. METHODS We evaluated the association between exposure to arsenic, measured in toenails, and blood DNA methylation in Alu and Long Interspersed Nucleotide Element-1 (LINE-1) repetitive elements in elderly men environmentally exposed to low levels of arsenic. We also explored potential effect modification by plasma folate, cobalamin (vitamin B12), and pyridoxine (vitamin B6). The study population was 581 participants from the Normative Aging Study in Boston, of whom 434, 140, and 7 had 1, 2, and 3 visits, respectively, between 1999-2002 and 2006-2007. We used mixed-effects models and included interaction terms to assess potential effect modification by nutritional factors. RESULTS There was a trend of increasing Alu and decreasing LINE-1 DNA methylation as arsenic exposure increased. In subjects with plasma folate below the median (< 14.1 ng/ml), arsenic was positively associated with Alu DNA methylation (β=0.08 [95% confidence interval = 0.03 to 0.13] for one interquartile range [0.06μg/g] increase in arsenic) while a negative association was observed in subjects with plasma folate above the median (β=-0.08 [-0.17 to 0.01]). CONCLUSIONS We found an association between arsenic exposure and DNA methylation in Alu repetitive elements that varied by folate level. This suggests a potential role for nutritional factors in arsenic toxicity. PMID:22833016

  5. Blast94: Bromine latitudinal air/sea transect 1994. Report on oceanic measurements of methyl bromide and other compounds. Technical memo

    SciTech Connect

    Lobert, J.M.; Butler, J.H.; Geller, L.S.; Yvon, S.A.; Montzka, S.A.

    1996-02-01

    Methyl bromide (CH3Br) is of particular interest because it is both produced and consumed in the ocean, thus allowing the ocean to act as a buffer for CH3Br in the atmosphere. The main objective of the two NOAA/CMDL Bromine Latitudinal Air/Sea Transect Expeditions has been to resolve the discrepancy in previously reported data for oceanic CH3Br, and to extend the understanding of the distribution and cycling of CH3Br between the atmosphere and ocean. This was pursued by making frequent, shipboard measurements of CH3Br in the surface water and the marine atmosphere along the cruise tracks and by obtaining depth profiles of CH3Br at selected stations. Secondary objectives included obtaining atmospheric and surface water data for other methyl halides, most notably CH3Cl, CH3I, CH2Br2, and CHBr3.

  6. Effects of soil type, moisture content, redox potential and methyl bromide fumigation on Kd values of radio-selenium in soil.

    PubMed

    Ashworth, D J; Moore, J; Shaw, G

    2008-07-01

    Understanding the processes that determine the solid-liquid partitioning (K(d) value) of Se is of fundamental importance in assessing the risk associated with the disposal of radio-selenium-containing waste. Using a mini-column (rather than batch) approach, K(d) values for (75)Se were determined over time in relation to soil moisture content (field capacity or saturated), redox potential and methyl bromide fumigation (used to disrupt the soil microbial population) in three contrasting soil types: clay loam, organic and sandy loam. The K(d) values were generally in the range 50-500 L kg(-1), with mean soil K(d) increasing with increasing organic matter content. Saturation with water lowered the measured redox potentials in the soils. However, only in the sandy loam soil did redox potential become negative, and this led to an increase in (75)Se K(d) value in this soil. Comparison of the data with the Eh-pH stability diagram for Se suggested that such strong reduction may have been consistent with the formation of the insoluble Se species, selenide. These findings, coupled with the fact that methyl bromide fumigation had no discernible effect on (75)Se K(d) value in the sandy loam soil, suggest that geochemical, rather than microbial, processes controlled (75)Se partitioning. The inter-relations between soil moisture content, redox potential and Se speciation should be considered in the modelling and assessment of radioactive Se fate and transport in the environment. PMID:18328605

  7. Severe peripheral neuropathy after exposure to monosodium methyl arsonate.

    PubMed

    Hessl, S M; Berman, E

    1982-05-01

    A case of severe peripheral neuropathy after several days of exposure to a pesticide spray containing monosodium methyl arsonate (MSMA) is reported. The clinical manifestations of symmetrical peripheral neuropathy with stocking-glove sensory deficit, decreased position sense, decreased and absent deep tendon reflexes, and muscle wasting are consistent with those described in other cases of arsenic intoxication. The anemia, leukopenia, and bone marrow changes of dyserythropoiesis in this case are also similar to those previously described with arsenic intoxication. The authors discuss the possible contribution of toxicity from exposure to other pesticides.

  8. Persistent modification of Na{sub v}1.9 following chronic exposure to insecticides and pyridostigmine bromide

    SciTech Connect

    Nutter, Thomas J. Cooper, Brian Y.

    2014-06-15

    Many veterans of the 1991 Gulf War (GW) returned from that conflict with a widespread chronic pain affecting deep tissues. Recently, we have shown that a 60 day exposure to the insecticides permethrin, chlorpyrifos, and pyridostigmine bromide (NTPB) had little influence on nociceptor action potential forming Na{sub v}1.8, but increased K{sub v}7 mediated inhibitory currents 8 weeks after treatment. Using the same exposure regimen, we used whole cell patch methods to examine whether the influences of NTPB could be observed on Na{sub v}1.9 expressed in muscle and vascular nociceptors. During a 60 day exposure to NTPB, rats exhibited lowered muscle pain thresholds and increased rest periods, but these measures subsequently returned to normal levels. Eight and 12 weeks after treatments ceased, DRG neurons were excised from the sensory ganglia. Whole cell patch studies revealed little change in voltage dependent activation and deactivation of Na{sub v}1.9, but significant increases in the amplitude of Na{sub v}1.9 were observed 8 weeks after exposure. Cellular studies, at the 8 week delay, revealed that NTPB also significantly prolonged action potential duration and afterhyperpolarization (22 °C). Acute application of permethrin (10 μM) also increased the amplitude of Na{sub v}1.9 in skin, muscle and vascular nociceptors. In conclusion, chronic exposure to Gulf War agents produced long term changes in the amplitude of Na{sub v}1.9 expressed in muscle and vascular nociceptors. The reported increases in K{sub v}7 amplitude may have been an adaptive response to increased Na{sub v}1.9, and effectively suppressed behavioral pain measures in the post treatment period. Factors that alter the balance between Na{sub v}1.9 and K{sub v}7 could release spontaneous discharge and produce chronic deep tissue pain. - Highlights: • Rats were treated 60 days with permethrin, chlorpyrifos and pyridostigmine bromide. • 8 weeks after treatments, Nav1.9 activation and deactivation were

  9. Preliminary study of propyl bromide exposure among New Jersey dry cleaners as a result of a pending ban on perchloroethylene.

    PubMed

    Blando, James D; Schill, Donald P; De La Cruz, Mary Pauline; Zhang, Lin; Zhang, Junfeng

    2010-09-01

    Many states are considering, and some states have actively pursued, banning the use of perchloroethylene (PERC) in dry cleaning establishments. Proposed legislation has led many dry cleaners to consider the use of products that contain greater than 90% n-propyl bromide (n-PB; also called 1-bromopropane or 1-BP). Very little information is known about toxicity and exposure to n-PB. Some n-PB-containing products are marketed as nonhazardous and "green" or "organic." This has resulted in some users perceiving the solvent as nontoxic and has resulted in at least one significant poisoning incident in New Jersey. In addition, many dry cleaning operators may not realize that the machine components and settings must be changed when converting from PERC to n-PB containing products. Not performing these modifications may result in overheating and significant leaks in the dry cleaning equipment. A preliminary investigation was conducted of the potential exposures to n-PB and isopropyl bromide (iso-PB; also called 2-bromopropane or 2-BP) among dry cleaners in New Jersey who have converted their machines from PERC to these new solvent products. Personal breathing zone and area samples were collected using the National Institute for Occupational Safety and Health Sampling and Analytical Method 1025, with a slight modification to gas chromatography conditions to facilitate better separation of n-PB from iso-PB. During the preliminary investigation, exposures to n-PB among some workers in two of three shops were measured that were greater than the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) for n-PB. The highest exposure measured among a dry cleaning machine operator was 54 parts per million (ppm) as an 8-hr time-weighted average, which is more than 5 times the ACGIH TLV of 10 ppm. The preliminary investigation also found that the work tasks most likely to result in the highest short-term exposures included the introduction of

  10. Modeling tribal exposures to methyl mercury from fish consumption.

    PubMed

    Xue, Jianping; Zartarian, Valerie; Mintz, Bruce; Weber, Marc; Bailey, Ken; Geller, Andrew

    2015-11-15

    Exposure assessment and risk management considerations for tribal fish consumption are different than for the general U.S. population because of higher fish intake from subsistence fishing and/or from unique cultural practices. This research summarizes analyses of available data and methodologies for estimating tribal fish consumption exposures to methyl mercury (MeHg). Large MeHg fish tissue data sets from the Environmental Protections Agency's (EPA's) Office of Water, USGS's EMMMA program, and other data sources, were integrated, analyzed, and combined with fish intake (consumption) data for exposure analyses using EPA's SHEDS-Dietary model. Results were mapped with GIS tools to depict spatial distributions of the MeHg in fish tissues and fish consumption exposure patterns. Contribution analyses indicates the major sources for those exposures, such as type and length of fish, geographical distribution (water bodies), and dietary exposure patterns. Sensitivity analyses identify the key variables and exposure pathways. Our results show that MeHg exposure of tribal populations from fish are about 3 to 10 times higher than the US general population and that exposure poses potential health risks. The estimated risks would be reduced as much as 50%, especially for high percentiles, just by avoiding consumption of fish species with higher MeHg concentrations such as walleye and bowfin, even without changing total fish intake. These exposure assessment methods and tools can help inform decisions regarding meal sizes and frequency, types of fish and water bodies to avoid, and other factors to minimize exposures and potential health risks from contaminated fish on tribal lands. PMID:26151654

  11. Reverse osmosis membrane composition, structure and performance modification by bisulphite, iron(III), bromide and chlorite exposure.

    PubMed

    Ferrer, O; Gibert, O; Cortina, J L

    2016-10-15

    Reverse osmosis (RO) membrane exposure to bisulphite, chlorite, bromide and iron(III) was assessed in terms of membrane composition, structure and performance. Membrane composition was determined by Rutherford backscattering spectrometry (RBS) and membrane performance was assessed by water and chloride permeation, using a modified version of the solution-diffusion model. Iron(III) dosage in presence of bisulphite led to an autooxidation of the latter, probably generating free radicals which damaged the membrane. It comprised a significant raise in chloride passage (chloride permeation coefficient increased 5.3-5.1 fold compared to the virgin membrane under the conditions studied) rapidly. No major differences in terms of water permeability and membrane composition were observed. Nevertheless, an increase in the size of the network pores, and a raise in the fraction of aggregate pores of the polyamide (PA) layer were identified, but no amide bond cleavage was observed. These structural changes were therefore, in accordance with the transport properties observed. PMID:27470468

  12. Morphology and local organization of water-containing (1R,2S)-dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide reverse micelles dispersed in toluene.

    PubMed

    Longo, Alessandro; Giannici, Francesco; Portale, Giuseppe; Banerjee, Dipanjan; Calandra, Pietro; Turco Liveri, Vincenzo

    2014-08-28

    The structure of (1R,2S)-dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide (DMEB) reverse micelles, at various water-to-surfactant molar ratio (Rw, Rw = [water]/[DMEB]) and DMEB concentrations, has been investigated by small angle X-ray scattering (SAXS) and extended X-ray absorption fine structure spectroscopy (EXAFS). SAXS data of dry reverse micelles are consistent with a model of spherical hydrophilic core surrounded by DMEB alkyl chains whose polydispersity decreases significantly with surfactant concentration. By adding water, a sphere to cylinder transition occurs leading to a one-dimensional growth of reverse micellar cores with Rw and surfactant concentration. The observed behavior was taken as an indication that water molecules are confined in the core of DMEB reverse micelles, quite uniformly distributed among them and mainly located among surfactant head groups. EXAFS data allow to focus within the hydrophilic micellar core to solve the short range local environment around the Br(-) counterion and to follow its changing with surfactant concentration and Rw. Analysis of Fourier transform of the EXAFS spectra indicates the existence of a local order nearby the bromide ions; pointing toward a quite structured hydrophilic core of DMEB reverse micelles. However, as a consequence of the fluid nature of reverse micelles, such local order is lower than that found in the lamellar structure of solid DMEB. Water confinement within the reverse micellar cores induces an increase of the local disorder suggesting an enhancement of the micellar core dynamics.

  13. Morphology and local organization of water-containing (1R,2S)-dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide reverse micelles dispersed in toluene

    NASA Astrophysics Data System (ADS)

    Longo, Alessandro; Giannici, Francesco; Portale, Giuseppe; Banerjee, Dipanjan; Calandra, Pietro; Liveri, Vincenzo Turco

    2014-08-01

    The structure of (1R,2S)-dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide (DMEB) reverse micelles, at various water-to-surfactant molar ratio (Rw, Rw = [water]/[DMEB]) and DMEB concentrations, has been investigated by small angle X-ray scattering (SAXS) and extended X-ray absorption fine structure spectroscopy (EXAFS). SAXS data of dry reverse micelles are consistent with a model of spherical hydrophilic core surrounded by DMEB alkyl chains whose polydispersity decreases significantly with surfactant concentration. By adding water, a sphere to cylinder transition occurs leading to a one-dimensional growth of reverse micellar cores with Rw and surfactant concentration. The observed behavior was taken as an indication that water molecules are confined in the core of DMEB reverse micelles, quite uniformly distributed among them and mainly located among surfactant head groups. EXAFS data allow to focus within the hydrophilic micellar core to solve the short range local environment around the Br- counterion and to follow its changing with surfactant concentration and Rw. Analysis of Fourier transform of the EXAFS spectra indicates the existence of a local order nearby the bromide ions; pointing toward a quite structured hydrophilic core of DMEB reverse micelles. However, as a consequence of the fluid nature of reverse micelles, such local order is lower than that found in the lamellar structure of solid DMEB. Water confinement within the reverse micellar cores induces an increase of the local disorder suggesting an enhancement of the micellar core dynamics.

  14. In Brief: Agreement signed for NSF participation in IODP; Asian dust storms' intensity, scale grow; Continued use of methyl bromide allowed

    NASA Astrophysics Data System (ADS)

    Jacobs, Judith; Showstack, Randy

    2004-04-01

    The U.S. National Science Foundation on 30 March signed a cooperative agreement with the Joint Oceanographic Institutions (JOI) in Washington, D.C., to lead U.S. participation in the Integrated Ocean Drilling Program (IODP). Large-scale, destructive dust and sand storms that originate in the dry regions of northern China and Mongolia are plaguing the Korean peninsula, Japan and other parts of northeast Asia nearly five times more frequently than in the 1950s, participants in a meeting sponsored by the U.N. Environment Programme (UNEP) learned on 30 March. Twelve countries have received ``critical use exemptions'' to continue using limited amounts of the pesticide methyl bromide in 2005.

  15. Palladium-catalyzed carbonylative coupling of (2-azaaryl)methyl anion equivalents with (hetero)aryl bromides.

    PubMed

    Jusseau, Xavier; Yin, Hongfei; Lindhardt, Anders T; Skrydstrup, Troels

    2014-11-24

    Conditions for the palladium-catalyzed coupling of (2-pyridyl)acetones with aryl bromides have been developed. Followed by an acid-promoted deacetylation step, the desired 1-(het)aryl-2-(2-pyridyl)ethanones were obtained in good to excellent yields with high functional group tolerance. Test reactions revealed that both the addition of MgCl2 and a specifically positioned heteroatom in the heteroaromatic ring were crucial for product formation indicating the importance of a chelated intermediate in the reaction mechanism. The reaction conditions proved suitable for a number of 5- and 6-membered heteroaromatic starting materials affording all products in good yields. The utility of the obtained 1-(het)aryl-2-(2-pyridyl)ethanones was demonstrated by the straightforward synthesis of several multiaromatic derivatives in only few additional steps.

  16. Association of second hand smoke exposures with DNA methylation in bladder carcinomas

    PubMed Central

    Wilhelm-Benartzi, Charlotte S.; Christensen, Brock C.; Koestler, Devin C.; Houseman, E. Andres; Schned, Alan R.; Karagas, Margaret R.; Kelsey, Karl T.; Marsit, Carmen J.

    2011-01-01

    Background The association between secondhand smoke (SHS) exposure and bladder cancer is inconclusive. Epigenetic alterations in bladder tumors have been linked to primary cigarette smoking and could add to the biological plausibility of an association between SHS exposure and bladder cancer. Hypothesis SHS exposure is associated with DNA methylation in bladder tumors. Methods Using an array-based approach, we profiled DNA methylation from never smoking cases of incident bladder cancer. Analyses examined associations between individual loci’s methylation with SHS variables (exposure in adulthood, childhood, occupationally and total exposure). A canonical pathway analysis was used to find pathways significantly associated with each SHS exposure type. Results There is a trend towards increased methylation of numerous CpG loci with increasing exposure to adulthood, occupational and total SHS. Discrete associations between methylation extent of several CpG loci and SHS exposures demonstrated significantly increased methylation of these loci across all types of SHS exposure. CpGs with SHS-related methylation alterations were associated with genes in pathways involved in carcinogenesis, immune modulation and immune signaling. Interpretation Exposure to SHS in adulthood, childhood, occupationally and in total are each significantly associated with changes in DNA methylation of several CpG loci in bladder tumors, adding biological plausibility to SHS as a risk factor for bladder cancer. PMID:21660454

  17. Phasing-out of methyl bromide (CH3Br) and usage of sulfuryl fluoride (SO2F2) for pest control in Europe

    NASA Astrophysics Data System (ADS)

    Reimann, S.; Brunner, D.; Vollmer, M. K.; Henne, S.; Maione, M.; Arduini, I.

    2011-12-01

    Methyl bromide (CH3Br) has been widely used for fumigation in agriculture, in food mills and for transport applications. Due to its high ozone-depleting potential, its use has been banned within the Montreal Protocol and its amendments, except for quarantine/pre-shipment uses. This led to a decline of global atmospheric background concentrations and of world-wide emissions. In Europe, emissions have declined concurrently and a generally good compliance with legislation is suggested based on emission estimates using inverse modelling of continuous measurements from the European high-altitude sites Jungfraujoch (Switzerland) and Monte Cimone (Italy). However, episodic pollution events of CH3Br show a violation of international legislation, as this substance has been banned in Europe from 2007 onwards in agriculture and from 2010 in quarantine/pre-shipment uses. Sulfuryl fluoride (SO2F2) is one of the replacement compounds for CH3Br in food processing structures. SO2F2 does not affect the ozone layer but is a potent greenhouse gas (100-year GWP: 4740) with a lifetime of 36 years. European emissions of SO2F2 are estimated by using measurements at Jungfraujoch. Large pollution events are very sporadic but consistently linked to emissions during long weekends and public holidays, presumably a preferable time to fumi-gate food processing structures.

  18. Determination of atmospheric methyl bromide by cryotrapping-gas chromatography and application to soil kinetic studies using a dynamic dilution system.

    PubMed

    Kerwin, R A; Crill, P M; Talbot, R W; Hines, M E; Shorter, J H; Kolb, C E; Harriss, R C

    1996-03-01

    Methyl bromide (CH(3)Br) is considered to be a major source of stratospheric Br, which contributes to the destruction of ozone. It is therefore necessary to understand the natural sinks of this compound and to accurately measure ambient mixing ratios. Methodology is described for the measurement of atmospheric CH(3)Br by cryotrapping-gas chromatography and its application to soil kinetics. A 2-propanol/dry ice cryotrap was used to preconcentrate CH(3)Br in standard and air samples, with subsequent detection using a gas chromatograph equipped with an O(2)-doped electron capture detector (GC-ECD). The GC-ECD cryotrapping method had a detection limit of 0.23 pmol of CH(3)Br. This is equivalent to the amount of CH(3)Br in a 500 mL sample of ambient air at the estimated northern hemisphere atmospheric mixing ratio of 11 parts per trillion by volume (pptv). A dynamic dilution system was developed to produce mixing ratios of CH(3)Br ranging between 4 and 1000 pptv. Calibrated mixing ratios of CH(3)Br produced with the dilution system were used to determine soil uptake kinetics employing a dynamic soil incubation method.

  19. Ambient PM exposure and DNA methylation in tumor suppressor genes: a cross-sectional study

    PubMed Central

    2011-01-01

    Exposure to ambient air particles matter (PM) has been associated with increased risk of lung cancer. Aberrant tumor suppressor gene promoter methylation has emerged as a promising biomarker for cancers, including lung cancer. Whether exposure to PM is associated with peripheral blood leukocyte (PBL) DNA methylation in tumor suppressor genes has not been evaluated. In 63 male healthy steel workers with well-characterized exposure to metal-rich particles nearby Brescia, Italy, we evaluated whether exposure to PM and metal components was associated with PBL DNA methylation in 4 tumor suppressor genes (i.e., APC, p16, p53 and RASSF1A). Blood samples were obtained on the 1st (baseline) and 4th day (post-exposure) of the same work week and DNA methylation was measured using pyrosequencing. A linear mixed model was used to examine the correlations of the exposure with promoter methylation levels. Mean promoter DNA methylation levels of APC or p16 were significantly higher in post-exposure samples compared to that in baseline samples (p-values = 0.005 for APC, and p-value = 0.006 for p16). By contrast, the mean levels of p53 or RASSF1A promoter methylation was decreased in post-exposure samples compared to that in baseline samples (p-value = 0.015 for p53; and p-value < 0.001 for RASSF1A). In post-exposure samples, APC methylation was positively associated with PM10 (β = 0.27, 95% CI: 0.13-0.40), and PM1 (β = 0.23, 95% CI: 0.09-0.38). In summary, ambient PM exposure was associated with PBL DNA methylation levels of tumor suppressor genes of APC, p16, p53 and RASSF1A, suggesting that such methylation alterations may reflect processes related to PM-induced lung carcinogenesis. PMID:21878113

  20. DOSE-RESPONSE MODELING FOR THE ASSESSMENT OF CUMULATIVE RISK DUE TO EXPOSURE TO N-METHYL CARBAMATE PESTICIDES

    EPA Science Inventory

    The US EPAs N-Methyl Carbamate Cumulative Risk Assessment (NMCRA) assesses the effect on acetylcholine esterase (AChE) activity of exposure to 10 N-methyl carbamate (NMC) pesticides through dietary, drinking water, and residential exposures.

  1. Locomotor and sensorimotor performance deficit in rats following exposure to pyridostigmine bromide, DEET, and permethrin, alone and in combination.

    PubMed

    Abou-Donia, M B; Goldstein, L B; Jones, K H; Abdel-Rahman, A A; Damodaran, T V; Dechkovskaia, A M; Bullman, S L; Amir, B E; Khan, W A

    2001-04-01

    Since their return from Persian Gulf War (PGW), many veterans have complained of symptoms including muscle and joint pain, ataxia, chronic fatigue, headache, and difficulty with concentration. The causes of the symptoms remain unknown. Because these veterans were exposed to a combination of chemicals including pyridostigmine bromide (PB), DEET, and permethrin, we investigated the effects of these agents, alone and in combination, on the sensorimotor behavior and central cholinergic system of rats. Male Sprague-Dawley rats (200-250 gm) were treated with DEET (40 mg/kg, dermal) or permethrin (0.13 mg/kg, dermal), alone and in combination with PB (1.3 mg/kg, oral, last 15 days only), for 45 days. Sensorimotor ability was assessed by a battery of behavioral tests that included beam-walk score, beam-walk time, incline plane performance, and forepaw grip on days 30 and 45 following the treatment. On day 45 the animals were sacrificed, and plasma and CNS cholinesterase, and brain choline acetyl transferase, muscarinic and nicotinic acetylcholine receptors were evaluated. Animals treated with PB, alone or in combination with DEET and permethrin, showed a significant deficit in beam-walk score as well as beam-walk time as compared with controls. Treatment with either DEET or permethrin, alone or in combination with each other, did not have a significant effect on beam-walk score. All chemicals, alone or in combination, resulted in a significant impairment in incline plane testing on days 30 and 45 following treatment. Treatment with PB, DEET, or permethrin alone did not have any inhibitory effect on plasma or brain cholinesterase activities, except that PB alone caused moderate inhibition in midbrain acetylcholinesterase (AChE) activity. Treatment with permethrin alone caused significant increase in cortical and cerebellar AChE activity. A combination of DEET and permethrin or PB and DEET led to significant decrease in AChE activity in brainstem and midbrain and brainstem

  2. Locomotor and sensorimotor performance deficit in rats following exposure to pyridostigmine bromide, DEET, and permethrin, alone and in combination.

    PubMed

    Abou-Donia, M B; Goldstein, L B; Jones, K H; Abdel-Rahman, A A; Damodaran, T V; Dechkovskaia, A M; Bullman, S L; Amir, B E; Khan, W A

    2001-04-01

    Since their return from Persian Gulf War (PGW), many veterans have complained of symptoms including muscle and joint pain, ataxia, chronic fatigue, headache, and difficulty with concentration. The causes of the symptoms remain unknown. Because these veterans were exposed to a combination of chemicals including pyridostigmine bromide (PB), DEET, and permethrin, we investigated the effects of these agents, alone and in combination, on the sensorimotor behavior and central cholinergic system of rats. Male Sprague-Dawley rats (200-250 gm) were treated with DEET (40 mg/kg, dermal) or permethrin (0.13 mg/kg, dermal), alone and in combination with PB (1.3 mg/kg, oral, last 15 days only), for 45 days. Sensorimotor ability was assessed by a battery of behavioral tests that included beam-walk score, beam-walk time, incline plane performance, and forepaw grip on days 30 and 45 following the treatment. On day 45 the animals were sacrificed, and plasma and CNS cholinesterase, and brain choline acetyl transferase, muscarinic and nicotinic acetylcholine receptors were evaluated. Animals treated with PB, alone or in combination with DEET and permethrin, showed a significant deficit in beam-walk score as well as beam-walk time as compared with controls. Treatment with either DEET or permethrin, alone or in combination with each other, did not have a significant effect on beam-walk score. All chemicals, alone or in combination, resulted in a significant impairment in incline plane testing on days 30 and 45 following treatment. Treatment with PB, DEET, or permethrin alone did not have any inhibitory effect on plasma or brain cholinesterase activities, except that PB alone caused moderate inhibition in midbrain acetylcholinesterase (AChE) activity. Treatment with permethrin alone caused significant increase in cortical and cerebellar AChE activity. A combination of DEET and permethrin or PB and DEET led to significant decrease in AChE activity in brainstem and midbrain and brainstem

  3. Capture of methyl bromide emissions with activated carbon following the fumigation of a small building contaminated with a Bacillus anthracis spore simulant.

    PubMed

    Wood, Joseph P; Clayton, Mathew J; McArthur, Timothy; Serre, Shannon D; Mickelsen, Leroy; Touati, Abderrahmane

    2015-02-01

    A wide-area Bacillus anthracis spore contamination incident will present immense challenges related to decontamination capacity. For this reason, fumigation with methyl bromide (MeBr) has been proposed as a potential remediation option. Although a few bench-scale laboratory studies have been conducted to evaluate activated carbon for the capture of MeBr, these studies were conducted at conditions replicating commodity fumigation using relatively low MeBr concentrations, temperatures, and/or relative humidity (RH) levels. The more rigorous MeBr fumigation requirements to fully inactivate B. anthracis spores are much more of a challenge for an activated carbon system (ACS) to capture MeBr, and warrant their own investigation. Further, while the aforementioned studies have shown activated carbon to be a possible option for the capture of MeBr in gas streams, these tests were conducted at laboratory bench scale, and thus lack operational perspective and data. Thus, we present for the first time the results of a full-scale study to evaluate an ACS employed for the capture of MeBr at conditions that would be used for decontaminating a building structure contaminated with B. anthracis spores. Airflow rate, temperature, RH, and MeBr levels were measured within the ACS during its operation. Despite the relatively high humidity, temperature, and MeBr levels, the MeBr capture efficiency of the ACS was demonstrated to be more than 99%. The concentration of MeBr exhausted from the structure was reduced from 41,000 to 136 ppmv in 3.5 hr, corresponding to an overall atmospheric emission rate of less than 2 kg. The practical adsorption rate of the ACS was determined to be 4.83 kg MeBr/100 kg carbon. The information and data presented here will facilitate future use of this technology when fumigating with MeBr.

  4. Emissions and distribution of methyl bromide in field beds applied at two rates and covered with two types of plastic mulches.

    PubMed

    Ou, Li-Tse; Thomas, John E; Allen, L Hartwell; Vu, Joseph C; Dickson, Donald W

    2007-01-01

    A field experiment was conducted to compare two plastic mulches and two application rates on surface emissions and subsurface distribution of methyl bromide (MBr) in field beds in Florida. Within 30 minutes after injection of MBr to 30 cm depth, MBr had diffused upward to soil surface in all beds covered with polyethylene film (PE) or virtually impermeable film (VIF) and applied at a high rate (392 kg/ha) and a low rate (196 kg/ha). Due to the highly permeable nature of PE, within 30 minutes after injection, MBr volatilized from the bed surfaces of the two PE-covered beds into the atmosphere. The amount of volatilization was greater for the high rate-treatment bed. On the other hand, volatilization of MBr from the bed surfaces of the two VIF-covered beds were negligible. Volatilization losses occurred from the edges of all the beds covered with PE or VIF and were greater from the high rate-treatment beds. Initial vertical diffusion of MBr in the subsurface of the beds covered with PE or VIF was mainly upward, as large concentrations of MBr were detected from near bed surfaces to 20 cm depth in these beds 30 minutes after injection and little or no MBr was found at 40 cm depth. The two VIF-covered beds exhibited greater MBr concentrations and longer resident times in the root zone (0.5-40 cm depth) than corresponding PE-covered beds. Concentrations of MBr in the root zone of the high rate-treatment beds were 3.6-6.1 times larger than the low rate-treatment beds during the first days after application. In conclusion, VIF promoted retention of MBr in the root zone and, if volatilization loss from bed edges can be blocked, volatilization loss from VIF-covered beds should be negligible.

  5. Real-World Verification of Methyl Bromide (CH3Br) Phase-Out in Europe and its Partial Replacement with Sulfuryl Fluoride (SO2F2)

    NASA Astrophysics Data System (ADS)

    Reimann, S.; Vollmer, M. K.; Brunner, D.; Henne, S.; Maione, M.; Arduini, I.

    2014-12-01

    In the last decades methyl bromide (CH3Br) has been widely used for pest control in agriculture, during transport and in susceptible environments such as grain elevators, flour mills. Due to its ozone-depleting properties most applications, except for quarantine-preshipment uses, are practically forbidden within the Montreal Protocol and its amendments. This led to a decline of both world-wide emissions and of global background concentrations. In Europe, emissions have declined concurrently, as CH3Br has not been allowed to be used in Europe from 2007 onwards in agriculture and from 2010 in quarantine/preshipment uses. Continuous measurements from the European high-altitude sites Jungfraujoch (Switzerland) and Monte Cimone (Italy) are used to verify this phase-out in different parts of Europe. Pollution events were still detected at these sites until around 2012, potentially indicating forbidden small scale usage of CH3Br in Europe. However, within the last 2 years the abundance and the height of these events have become very small - showing an overall good acceptance of the CH3Br ban in Europe. On the other hand, sulfuryl fluoride (SO2F2) is used as a partial replacement of CH3Br in the fumigation of food processing structures. It shows very distinct, sporadic peak events at the Jungfraujoch measurement site. SO2F2 does not affect the ozone layer but is a potent greenhouse gas (100-year GWP: 4740) with a lifetime of 36 years. European sources of SO2F2 were estimated by using measurements at Jungfraujoch.

  6. Vinyl bromide

    Integrated Risk Information System (IRIS)

    Vinyl bromide ; CASRN 593 - 60 - 2 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  7. Cyanogen bromide

    Integrated Risk Information System (IRIS)

    Cyanogen bromide ; CASRN 506 - 68 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  8. Developmental effects of methyl benzimidazolecarbamate following exposure during early pregnancy

    EPA Science Inventory

    Methyl 2-benzimidazolecarbamate (MBC) and its parent compound benomyl are used as agricultural fungicides. Both chemicals are embryotoxic if administered during organogenesis, and benomyl is teratogenic. Based on a previous study indicating a lack of maternal effects of MBC follo...

  9. DIETARY METHYL MERCURY EXPOSURE IN AMERICAN KESTRELS; PILOT STUDY

    EPA Science Inventory

    Anthropogenic mercury emissions have increased atmospheric mercury levels about threefold since the advent of industrial activity. Atmospheric deposition is the primary source of mercury in the environment hence mercury contamination has increased in similar fashion. Methyl mercu...

  10. PRKCZ methylation is associated with sunlight exposure in a North American but not a Mediterranean population.

    PubMed

    Aslibekyan, Stella; Dashti, Hassan S; Tanaka, Toshiko; Sha, Jin; Ferrucci, Luigi; Zhi, Degui; Bandinelli, Stefania; Borecki, Ingrid B; Absher, Devin M; Arnett, Donna K; Ordovas, Jose M

    2014-11-01

    Sunlight exposure has been shown to alter DNA methylation patterns across several human cell-types, including T-lymphocytes. Since epigenetic changes establish gene expression profiles, changes in DNA methylation induced by sunlight exposure warrant investigation. The purpose of this study was to assess the effects of sunlight exposure on CD4+ T-cell methylation patterns on an epigenome-wide scale in a North American population of European origin (n=991). In addition, we investigated the genetic contribution to epigenetic variation (methylQTL). We used linear regression to test the associations between methylation scores at 461,281 cytosine-phosphate-guanine (CpG) sites and sunlight exposure, followed by a genome-wide association analysis (methylQTL) to test for associations between methylation at the top CpG locus and common genetic variants, assuming an additive genetic model. We observed an epigenome-wide significant association between sunlight exposure and methylation status at cg26930596 (p=9.2×10(-8)), a CpG site located in protein kinase C zeta (PRKCZ), a gene previously shown to be entrained by light. MethylQTL analysis resulted in significant associations between cg26930596 and two intergenic single nucleotide polymorphisms on chromosome 3, rs4574216 (p=1.5×10(-10)) and rs4405858 (p=1.9×10(-9)). These common genetic variants reside downstream of WWTR1, a transcriptional co-activator of PRKCZ. Associations observed in the North American population, however, did not replicate in an independent Mediterranean cohort. Our preliminary results support the role of sunlight exposure in epigenetic processes, and lay the groundwork for future studies of the molecular link between sunlight and physiologic processes such as tumorigenesis and metabolism.

  11. PRKCZ methylation is associated with sunlight exposure in a North American but not a Mediterranean population

    PubMed Central

    Aslibekyan, Stella; Dashti, Hassan S.; Tanaka, Toshiko; Sha, Jin; Ferrucci, Luigi; Zhi, Degui; Bandinelli, Stefania; Borecki, Ingrid B.; Absher, Devin M.; Arnett, Donna K.; Ordovas, Jose M.

    2015-01-01

    Sunlight exposure has been shown to alter DNA methylation patterns across several human cell-types, including T-lymphocytes. Since epigenetic changes establish gene expression profiles, changes in DNA methylation induced by sunlight exposure warrant investigation. The purpose of this study was to assess the effects of sunlight exposure on CD4+ T-cell methylation patterns on an epigenome-wide scale in a North American population of European origin (n = 991). In addition, we investigated the genetic contribution to epigenetic variation (methylQTL). We used linear regression to test the associations between methylation scores at 461 281 cytosine-phosphate-guanine (CpG) sites and sunlight exposure, followed by a genome-wide association analysis (methylQTL) to test for associations between methylation at the top CpG locus and common genetic variants, assuming an additive genetic model. We observed an epigenome-wide significant association between sunlight exposure and methylation status at cg26930596 (p = 9.2 × 10−8), a CpG site located in protein kinase C zeta (PRKCZ), a gene previously shown to be entrained by light. MethylQTL analysis resulted in significant associations between cg26930596 and two intergenic single nucleotide polymorphisms on chromosome 3, rs4574216 (p = 1.5 × 10−10) and rs4405858 (p = 1.9 × 10−9). These common genetic variants reside downstream of WWTR1, a transcriptional co-activator of PRKCZ. Associations observed in the North American population, however, did not replicate in an independent Mediterranean cohort. Our preliminary results support the role of sunlight exposure in epigenetic processes, and lay the groundwork for future studies of the molecular link between sunlight and physiologic processes such as tumorigenesis and metabolism. PMID:25075435

  12. USE OF EXPOSURE-RELATED DOSE ESTIMATING MODEL (ERDEM) FOR ASSESSMENT OF AGGREGATE EXPOSURE OF INFANT AND CHILDREN TO N-METHYL CARBAMATE INSECTICIDES

    EPA Science Inventory

    A physiologically based pharmacokinetic (PBPK) model was developed within the Exposure Related Dose Estimating Model (ERDEM) framework to investigate selected exposure inputs related to recognized exposure scenarios of infants and children to N-methyl carbamate pesticides as spec...

  13. Exposure to persistent organic pollutants and sperm DNA methylation changes in Arctic and European populations.

    PubMed

    Consales, Claudia; Toft, Gunnar; Leter, Giorgio; Bonde, Jens Peter E; Uccelli, Raffaella; Pacchierotti, Francesca; Eleuteri, Patrizia; Jönsson, Bo A G; Giwercman, Aleksander; Pedersen, Henning S; Struciński, Paweł; Góralczyk, Katarzyna; Zviezdai, Valentyna; Spanò, Marcello

    2016-04-01

    Persistent organic pollutants (POPs), such as PCBs (polychlorinated biphenyls) and DDT [1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane], are environmental contaminants with potential endocrine disrupting activity. DNA methylation levels in peripheral blood lymphocytes have been associated with serum concentrations of POPs in Greenland Inuit and Korean populations. Greenland Inuits are characterized by the highest worldwide POP levels. In this cross-sectional study we evaluated the relationship between serum POP concentrations and DNA methylation levels in sperm of non-occupationally exposed fertile men from Greenland, Warsaw (Poland), and Kharkiv (Ukraine). Serum levels of PCB-153 [1,2,4-trichloro-5-(2,4,5-trichlorophenyl)benzene], as a proxy of the total PCBs body burden, and of p,p'-DDE [1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene], the main metabolite of DDT were measured. Sperm DNA methylation level was assessed globally by flow cytometric (FCM) immunodetection of 5-methyl-cytosines and at specific repetitive DNA sequences (Alu, LINE-1, Satα) by PCR-pyrosequencing after bisulfite conversion. Multivariate linear regression analysis was applied to investigate correlations between serum POP concentrations and DNA methylation. No consistent associations between exposure to POPs and sperm DNA methylation at repetitive DNA sequences were detected. A statistically significant global decrease in methylation was associated with exposure to either POP by FCM analysis. This is the first study to investigate environmental exposure to POPs and DNA methylation levels considering sperm as the target cells. Although POP exposure appears to have a limited negative impact on sperm DNA methylation levels in adult males, the global hypomethylation detected by one of the methods applied suggests that further investigation is warranted. PMID:26801515

  14. Global DNA methylation in gonads of adult zebrafish Danio rerio under bisphenol A exposure.

    PubMed

    Liu, Yan; Zhang, Yingying; Tao, Shiyu; Guan, Yongjing; Zhang, Ting; Wang, Zaizhao

    2016-08-01

    Altered DNA methylation is pervasively associated with changes in gene expression and signal transduction after exposure to a wide range of endocrine disrupting chemicals. As a weak estrogenic chemical, bisphenol A (BPA) has been extensively studied for reproductive toxicity. In order to explore the effects of BPA on epigenetic modification in gonads of zebrafish Danio rerio, we measured the global DNA methylation together with the gene expression of DNA methyltransferase (dnmts), glycine N-methyltransferase (gnmt), and ten-eleven translocation (tets) in gonads of D. rerio under BPA exposure by ELISA and quantitative real-time PCR method, respectively. The global level of DNA methylation was significantly decreased in ovaries after exposed to BPA for 7 days, and testes following 35-day exposure. Moreover, the global level of DNA methylation was also significantly reduced in testes after exposed to 15μg/L BPA for 7 days. Besides the alteration of the global level of DNA methylation, varying degrees of transcriptional changes of dnmts, gnmt and tets were detected in gonads of D. rerio under BPA exposure. The present study suggested that BPA might cause the global DNA demethylation in gonads of zebrafish by regulating the transcriptional changes of the DNA methylation/demethylation-associated genes (dnmts, gnmt, and tets). PMID:27101439

  15. Prenatal antidepressant exposure associated with CYP2E1 DNA methylation change in neonates

    PubMed Central

    Gurnot, Cécile; Martin-Subero, Ignacio; Mah, Sarah M; Weikum, Whitney; Goodman, Sarah J; Brain, Ursula; Werker, Janet F; Kobor, Michael S; Esteller, Manel; Oberlander, Tim F; Hensch, Takao K

    2015-01-01

    Some but not all neonates are affected by prenatal exposure to serotonin reuptake inhibitor antidepressants (SRI) and maternal mood disturbances. Distinguishing the impact of these 2 exposures is challenging and raises critical questions about whether pharmacological, genetic, or epigenetic factors can explain the spectrum of reported outcomes. Using unbiased DNA methylation array measurements followed by a detailed candidate gene approach, we examined whether prenatal SRI exposure was associated with neonatal DNA methylation changes and whether such changes were associated with differences in birth outcomes. Prenatal SRI exposure was first associated with increased DNA methylation status primarily at CYP2E1(βNon-exposed = 0.06, βSRI-exposed = 0.30, FDR = 0); however, this finding could not be distinguished from the potential impact of prenatal maternal depressed mood. Then, using pyrosequencing of CYP2E1 regulatory regions in an expanded cohort, higher DNA methylation status—both the mean across 16 CpG sites (P < 0.01) and at each specific CpG site (P < 0.05)—was associated with exposure to lower 3rd trimester maternal depressed mood symptoms only in the SRI-exposed neonates, indicating a maternal mood x SRI exposure interaction. In addition, higher DNA methylation levels at CpG2 (P = 0.04), CpG9 (P = 0.04) and CpG10 (P = 0.02), in the interrogated CYP2E1 region, were associated with increased birth weight independently of prenatal maternal mood, SRI drug exposure, or gestational age at birth. Prenatal SRI antidepressant exposure and maternal depressed mood were associated with altered neonatal CYP2E1 DNA methylation status, which, in turn, appeared to be associated with birth weight. PMID:25891251

  16. A Sandmeyer type reaction for bromination of 2-mercapto-1-methyl-imidazoline (N2C4H6S) into 2-bromo-1-methyl-imidazole (N2C4H5Br) in presence of copper(I) bromide.

    PubMed

    Lobana, Tarlok S; Sultana, Razia; Butcher, Ray J

    2011-11-21

    2-Mercapto-1-methyl-imidazoline (N(2)C(4)H(6)S) is converted at room temperature into 2-bromo-1-methyl-imidazole (N(2)C(4)H(5)Br) in presence of copper(I) bromide in acetonitrile-chloroform mixture via extrusion of sulfur as sulfate and oxidation of Cu(I) into Cu(II). 2-Bromo-1-methyl-imidazole was isolated as its self assembled tetranuclear Cu(II) cluster, [Cu(4)(η(1)-N-(N(2)C(4)H(5)Br)(4)(μ(4)-O)(μ-Br)(6)] 1 {η(1)-N-(N(2)C(4)H(5)Br) = 2-bromo-1-methyl-imidazole}. PMID:21960310

  17. Sun exposure related methylation in malignant and non-malignant skin lesions.

    PubMed

    Sathyanarayana, Ubaradka G; Moore, Angela Yen; Li, Lin; Padar, Asha; Majmudar, Kuntal; Stastny, Victor; Makarla, Prakash; Suzuki, Makoto; Minna, John D; Feng, Ziding; Gazdar, Adi F

    2007-01-01

    We investigated the aberrant promoter methylation status of 12 genes in skin lesions, both malignant (basal cell carcinomas (BCCs), n=68 and squamous cell carcinomas (SCCs), n=35) and non-malignant (tags, n=58) skin lesions and compared the results of lesions from sun exposed (SE) and sun protected (SP) regions. Methylation was studied using a methylation specific PCR (MSP) and methylation of CDH1 was also measured using a semi-quantitative fluorescence based real-time MSP method. The methylation index (MI) was calculated as the methylated fraction of the genes examined. In this report, we found high frequencies of methylation of several known or suspected tumor suppressor genes in tags and skin cancers. Among the 12 genes, for the cadherin genes CDH1 and CDH3 and for two of the laminin 5 encoding genes LAMA3 and LAMC2 methylation frequencies greater than 30% were noted in one or more specimen types. We investigated whether methylation was tumor related. Surprisingly, the differences in the methylation profile of genes among the three specimen types were modest, and the MI, indicators of overall methylation frequencies, was nearly identical. However, significant differences were noted in the frequencies of methylation among the three specimen types for the genes RASSF1A (P=0.002), CDH1 (P=0.007) and one or more of three CAD genes (P=0.02). Methylation was highly significantly related to sun exposure, and sun protected specimens had little or no methylation. As methylation of CDH1 was completely SE specific we analyzed all the skin samples using a semi-quantitative real-time PCR assay for the CDH1 gene. The concordance between standard MSP and real-time MSP for all the samples (n=161) was 75% (P<0.0001). While weak signals were detected in the SP samples by real time PCR, the differences between SE and SP specimens were 148 fold for tags and 390 fold for BCCs. These differences were highly significant (P<0.0001). These findings suggest that methylation commences in

  18. Effects of methyl mercury exposure on the growth of juvenile common loons

    USGS Publications Warehouse

    Kenow, K.P.; Gutreuter, S.; Hines, R.K.; Meyer, M.W.; Fournier, F.; Karasov, W.H.

    2003-01-01

    We conducted a dose-response laboratory study to quantify the level of mercury exposure associated with negative effects on the development of common loon chicks reared in captivity from hatch to 105 days. A dose regimen was implemented that provided exposure levels that bracketed relevant exposure levels of methyl mercury found in loon chicks across North America. We observed no overt signs of mercury toxicosis and detected no significant effect of dietary mercury exposure on growth or food consumption. However, asymptotic mass was lower in chicks that hatched from eggs collected from nests on low pH lakes relative to eggs from neutral pH lakes. Rapid excretion of methyl mercury during feather growth likely provides loon chicks protection from methyl mercury toxicity and may explain the lack of convincing toxicological findings in this study. Lake-source effects suggest that in ovo exposure to methyl mercury or other factors related to lake pH have consequences on chick development.

  19. Prenatal Exposure to DEHP Affects Spermatogenesis and Sperm DNA Methylation in a Strain-Dependent Manner.

    PubMed

    Prados, Julien; Stenz, Ludwig; Somm, Emmanuel; Stouder, Christelle; Dayer, Alexandre; Paoloni-Giacobino, Ariane

    2015-01-01

    Di-(2-ethylhexyl)phtalate (DEHP) is a plasticizer with endocrine disrupting properties found ubiquitously in the environment and altering reproduction in rodents. Here we investigated the impact of prenatal exposure to DEHP on spermatogenesis and DNA sperm methylation in two distinct, selected, and sequenced mice strains. FVB/N and C57BL/6J mice were orally exposed to 300 mg/kg/day of DEHP from gestation day 9 to 19. Prenatal DEHP exposure significantly decreased spermatogenesis in C57BL/6J (fold-change = 0.6, p-value = 8.7*10-4), but not in FVB/N (fold-change = 1, p-value = 0.9). The number of differentially methylated regions (DMRs) by DEHP-exposure across the entire genome showed increased hyper- and decreased hypo-methylation in C57BL/6J compared to FVB/N. At the promoter level, three important subsets of genes were massively affected. Promoters of vomeronasal and olfactory receptors coding genes globally followed the same trend, more pronounced in the C57BL/6J strain, of being hyper-methylated in DEHP related conditions. In contrast, a large set of micro-RNAs were hypo-methylated, with a trend more pronounced in the FVB/N strain. We additionally analyze both the presence of functional genetic variations within genes that were associated with the detected DMRs and that could be involved in spermatogenesis, and DMRs related with the DEHP exposure that affected both strains in an opposite manner. The major finding in this study indicates that prenatal exposure to DEHP can decrease spermatogenesis in a strain-dependent manner and affects sperm DNA methylation in promoters of large sets of genes putatively involved in both sperm chemotaxis and post-transcriptional regulatory mechanisms. PMID:26244509

  20. Prenatal Exposure to DEHP Affects Spermatogenesis and Sperm DNA Methylation in a Strain-Dependent Manner

    PubMed Central

    Somm, Emmanuel; Stouder, Christelle; Dayer, Alexandre; Paoloni-Giacobino, Ariane

    2015-01-01

    Di-(2-ethylhexyl)phtalate (DEHP) is a plasticizer with endocrine disrupting properties found ubiquitously in the environment and altering reproduction in rodents. Here we investigated the impact of prenatal exposure to DEHP on spermatogenesis and DNA sperm methylation in two distinct, selected, and sequenced mice strains. FVB/N and C57BL/6J mice were orally exposed to 300 mg/kg/day of DEHP from gestation day 9 to 19. Prenatal DEHP exposure significantly decreased spermatogenesis in C57BL/6J (fold-change = 0.6, p-value = 8.7*10-4), but not in FVB/N (fold-change = 1, p-value = 0.9). The number of differentially methylated regions (DMRs) by DEHP-exposure across the entire genome showed increased hyper- and decreased hypo-methylation in C57BL/6J compared to FVB/N. At the promoter level, three important subsets of genes were massively affected. Promoters of vomeronasal and olfactory receptors coding genes globally followed the same trend, more pronounced in the C57BL/6J strain, of being hyper-methylated in DEHP related conditions. In contrast, a large set of micro-RNAs were hypo-methylated, with a trend more pronounced in the FVB/N strain. We additionally analyze both the presence of functional genetic variations within genes that were associated with the detected DMRs and that could be involved in spermatogenesis, and DMRs related with the DEHP exposure that affected both strains in an opposite manner. The major finding in this study indicates that prenatal exposure to DEHP can decrease spermatogenesis in a strain-dependent manner and affects sperm DNA methylation in promoters of large sets of genes putatively involved in both sperm chemotaxis and post-transcriptional regulatory mechanisms. PMID:26244509

  1. Response to copper bromide exposure in Vicia sativa L. seeds: analysis of genotoxicity, nucleolar activity and mineral profile.

    PubMed

    Bellani, Lorenza M; Muccifora, Simonetta; Giorgetti, Lucia

    2014-09-01

    Copper bromide (CuBr2) effects on seed germination and plantlet development of Vicia sativa L. are evaluated through mitotic index, chromosome aberrations, nucleolar activity and mineral profile. CuBr2 induces a significant presence of micronuclei, sticky and c-metaphases, anaphase bridges and chromosome breaks. Increased number of nucleoli and scattering of AgNOR proteins from the nucleolus in the nuclear surface at CuBr2 1mM and in the cytoplasm at CuBr2 5mM, goes along with the decrease of root growth. In V. sativa embryo the content of many macro and micronutrients increases up to copper 1mM in agreement with reserve mobilization while at CuBr2 5mM some elements are present in lower amount. We hypothesize that inhibitory effects observed at 5mM are due either to a nutrient shortage or to a direct influence of copper on root cell division, evidenced by low mitotic index, high occurrence of chromosome aberrations and loss of material from the nucleolus.

  2. Exposure to methyl tertiary-butyl ether from oxygenated gasoline in Stamford, Connecticut

    SciTech Connect

    White, M.C.; Johnson, C.A.; Ashley, D.L.

    1995-05-01

    In 1993, state health officials in Connecticut invited the Centers for Disease Control and Prevention (CDC) to assist in an investigation of exposure to methyl tertiary-butyl ether in oxygenated gasoline in Stamford, Connecticut. Venous blood samples were collected from 14 commuters and from 30 other persons who worked in the vicinity of traffic or automobiles, and the samples were analyzed for methyl tertiary-butyl ether, tertiary-butyl alcohol, benzene, m-/p-xylene, o-xylene, and toluene. The highest levels of methyl tertiary-butyl ether in blood were measured among gasoline service station attendants (median = 15 {mu}g/l, range = 7.6-28.9 {mu}g/l). Blood levels of methyl tertiary-butyl ether were highly variable among persons who worked in car-repair shops (median = 1.73 {mu}g/l, range = 0.17-36.7 {mu}/l) and were generally lowest among commuters (median = 0.11 {mu}g/l, range = <0.05-2.60 {mu}g/l). Blood levels of methyl tertiary-butyl ether were correlated strongly with personal-breathing-zone samples of methyl tertiary-butyl ether and blood levels of other volatile organic compounds. This exposure information should prove useful to a future risk analysis of this high-volume chemical. 18 refs., 5 figs., 2 tabs.

  3. Modeling tribal exposures to methyl mercury from fish consumption

    EPA Science Inventory

    Exposure assessment and risk management considerations for tribal fish consumption are different than for the general U.S. population because of higher fish intake from subsistence fishing and/or from unique cultural practices. This research summarizes analyses of available data ...

  4. Effect of low-dose cadmium exposure on DNA methylation in the endangered European eel.

    PubMed

    Pierron, Fabien; Baillon, Lucie; Sow, Mohamedou; Gotreau, Salomé; Gonzalez, Patrice

    2014-01-01

    There is increasing evidence that epigenetics can play a key role in the etiology of diseases engendered by chronic pollutant exposure. Although epigenetics has received significant attention in the field of biomedicine during the last years, epigenetics research is surprisingly very limited in ecotoxicology. The aim of the present study was to investigate the possible effects of low-dose cadmium exposure on the DNA methylation profile in a critically endangered fish species, the European eel. Eels were exposed to environmentally realistic concentrations of cadmium (0.4 and 4 μg·L(-1)) during 45 days. The global CpG methylation status of eel liver was determined by means of a homemade ELISA assay. We then used a methylation-sensitive arbitrarily primed PCR method to identify genes that are differentially methylated between control and Cd-exposed eels. Our results show that cadmium exposure is associated with DNA hypermethylation and with a decrease in total RNA synthesis. Among hypermethylated sequences identified, several fragments presented high homologies with genes encoding for proteins involved in intracellular trafficking, lipid biosynthesis, and phosphatidic acid signaling pathway. In addition, few fragments presented high homologies with retrotransposon-like sequences. Our study illustrates how DNA methylation can be involved in the chronic stress response to Cd in fish. PMID:24328039

  5. Benzopyrene exposure disrupts DNA methylation and growth dynamics in breast cancer cells

    SciTech Connect

    Sadikovic, Bekim; Rodenhiser, David I. . E-mail: drodenhi@uwo.ca

    2006-11-01

    Exposures to environmental carcinogens and unhealthy lifestyle choices increase the incidence of breast cancer. One such compound, benzo(a)pyrene (BaP), leads to covalent DNA modifications and the deregulation of gene expression. To date, these mechanisms of BaP-induced carcinogenesis are poorly understood, particularly in the case of breast cancer. We tested the effects of BaP exposure on cellular growth dynamics and DNA methylation in four breast cancer cell lines since disruptions in DNA methylation lead to deregulated gene expression and the loss of genomic integrity. We observed robust time- and concentration-dependent loss of proliferation, S phase and G2M accumulation and apoptosis in p53 positive MCF-7 and T47-D cells. We observed minimal responses in p53 negative HCC-1086 and MDA MB 231 cells. Furthermore, BaP increased p53 levels in both p53 positive cell lines, as well as p21 levels in MCF-7 cells, an effect that was prevented by the p53-specific inhibitor pifithrin-{alpha}. No changes in global levels of DNA methylation levels induced by BaP were detected by the methyl acceptor assay (MAA) in any cell line, however, methylation profiling by AIMS (amplification of intermethylated sites) analysis showed dynamic, sequence-specific hypo- and hypermethylation events in all cell lines. We also identified BaP-induced hypomethylation events at a number of genomic repeats. Our data confirm the p53-specific disruption of the cell cycle as well as the disruption of DNA methylation as a consequence of BaP treatment, thus reinforcing the link between environmental exposures, DNA methylation and breast cancer.

  6. REFINED PBPK MODEL OF AGGREGATE EXPOSURE TO METHYL TERTIARY-BUTYL ETHER

    EPA Science Inventory

    Aggregate (multiple pathway) exposures to methyl tertiary-butyl ether (MTBE) in air and water occur via dermal, inhalation, and oral routes. Previously, physiologically-based pharmacokinetic (PBPK) models have been used to quantify the kinetic behavior of MTBE and its primary met...

  7. Methyl Iodide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl iodide (MeI, iodomethane, CH3I) was reported as a potential alternative to the stratospheric ozone-depleting fumigant methyl bromide (MeBr) in the mid-1990s (Sims et al., 1995; Ohr et al., 1996). It has since received significant research attention to determine its environmental fate and tran...

  8. Influence of Prenatal Arsenic Exposure and Newborn Sex on Global Methylation of Cord Blood DNA

    PubMed Central

    Pilsner, J. Richard; Hall, Megan N.; Liu, Xinhua; Ilievski, Vesna; Slavkovich, Vesna; Levy, Diane; Factor-Litvak, Pam; Yunus, Mahammad; Rahman, Mahfuzar; Graziano, Joseph H.; Gamble, Mary V.

    2012-01-01

    Background An emerging body of evidence indicates that early-life arsenic (As) exposure may influence the trajectory of health outcomes later in life. However, the mechanisms underlying these observations are unknown. Objective The objective of this study was to investigate the influence of prenatal As exposure on global methylation of cord blood DNA in a study of mother/newborn pairs in Matlab, Bangladesh. Design Maternal and cord blood DNA were available from a convenience sample of 101 mother/newborn pairs. Measures of As exposure included maternal urinary As (uAs), maternal blood As (mbAs) and cord blood As (cbAs). Several measures of global DNA methylation were assessed, including the [3H]-methyl-incorporation assay and three Pyrosequencing assays: Alu, LINE-1 and LUMA. Results In the total sample, increasing quartiles of maternal uAs were associated with an increase in covariate-adjusted means of newborn global DNA methylation as measured by the [3H]-methyl-incorporation assay (quartile 1 (Q1) and Q2 vs. Q4; p = 0.06 and 0.04, respectively). Sex-specific linear regression analyses, while not reaching significance level of 0.05, indicated that the associations between As exposures and Alu, LINE-1 and LUMA were positive among male newborns (N = 58) but negative among female newborns (N = 43); tests for sex differences were borderline significant for the association of cbAs and mbAs with Alu (p = 0.05 and 0.09, respectively) and for the association between maternal uAs and LINE-1 (p = 0.07). Sex-specific correlations between maternal urinary creatinine and newborn methyl-incorporation, Alu and LINE-1 were also evident (p<0.05). Conclusions These results suggest that prenatal As exposure is associated with global DNA methylation in cord blood DNA, possibly in a sex-specific manner. Arsenic-induced epigenetic modifications in utero may potentially influence disease outcomes later in life. Additional studies are needed to confirm these findings

  9. Stress and combined exposure to low doses of pyridostigmine bromide, DEET, and permethrin produce neurochemical and neuropathological alterations in cerebral cortex, hippocampus, and cerebellum.

    PubMed

    Abdel-Rahman, A; Abou-Donia, Suzanne; El-Masry, Eman; Shetty, Ashok; Abou-Donia, Mohamed

    2004-01-23

    Exposure to a combination of stress and low doses of the chemicals pyridostigmine bromide (PB), DEET, and permethrin in adult rats, a model of Gulf War exposure, produces blood-brain barrier (BBB) disruption and neuronal cell death in the cingulate cortex, dentate gyrus, thalamus, and hypothalamus. In this study, neuropathological alterations in other areas of the brain where no apparent BBB disruption was observed was studied following such exposure. Animals exposed to both stress and chemical exhibited decreased brain acetylcholinesterase (AChE) activity in the midbrain, brainstem, and cerebellum and decreased m2 muscarinic acetylcholine (ACh) receptor ligand binding in the midbrain and cerebellum. These alterations were associated with significant neuronal cell death, reduced microtubule-associated protein (MAP-2) expression, and increased glial fibrillary acidic protein (GFAP) expression in the cerebral cortex and the hippocampal subfields CA1 and CA3. In the cerebellum, the neurochemical alterations were associated with Purkinje cell loss and increased GFAP immunoreactivity in the white matter. However, animals subjected to either stress or chemicals alone did not show any of these changes in comparison to vehicle-treated controls. Collectively, these results suggest that prolonged exposure to a combination of stress and the chemicals PB, DEET, and permethrin can produce significant damage to the cerebral cortex, hippocampus, and cerebellum, even in the absence of apparent BBB damage. As these areas of the brain are respectively important for the maintenance of motor and sensory functions, learning and memory, and gait and coordination of movements, such alterations could lead to many physiological, pharmacological, and behavioral abnormalities, particularly motor deficits and learning and memory dysfunction. PMID:14675905

  10. DNA methylation: a mechanism linking environmental chemical exposures to risk of autism spectrum disorders?

    PubMed Central

    Keil, Kimberly P.; Lein, Pamela J.

    2016-01-01

    There is now compelling evidence that gene by environment interactions are important in the etiology of autism spectrum disorders (ASDs). However, the mechanisms by which environmental factors interact with genetic susceptibilities to confer individual risk for ASD remain a significant knowledge gap in the field. The epigenome, and in particular DNA methylation, is a critical gene expression regulatory mechanism in normal and pathogenic brain development. DNA methylation can be influenced by environmental factors such as diet, hormones, stress, drugs, or exposure to environmental chemicals, suggesting that environmental factors may contribute to adverse neurodevelopmental outcomes of relevance to ASD via effects on DNA methylation in the developing brain. In this review, we describe epidemiological and experimental evidence implicating altered DNA methylation as a potential mechanism by which environmental chemicals confer risk for ASD, using polychlorinated biphenyls (PCBs), lead, and bisphenol A (BPA) as examples. Understanding how environmental chemical exposures influence DNA methylation and how these epigenetic changes modulate the risk and/or severity of ASD will not only provide mechanistic insight regarding gene-environment interactions of relevance to ASD but may also suggest potential intervention strategies for these and potentially other neurodevelopmental disorders. PMID:27158529

  11. Biological effects of short-term, high-concentration exposure to methyl isocyanate. I. Study objectives and inhalation exposure design

    SciTech Connect

    Dodd, D.E.; Frank, F.R.; Fowler, E.H.; Troup, C.M.; Milton, R.M.

    1987-06-01

    Early reports from India indicated that humans were dying within minutes to a few hours from exposure to methyl isocyanate (MIC). Attempts to explain the cause(s) of these rapid mortalities is where Union Carbide Corporation concentrated its post-Bhopal toxicologic investigations. The MIC studies involving rats and guinea pigs focused primarily on the consequences of acute pulmonary damage. All MIC inhalation exposures were acute, of short duration (mainly 15 min), and high in concentration. MIC vapors were statically generated in a double chamber exposure design. Precautionary measures taken during exposures are discussed. Guinea pigs were more susceptible than rats to MIC exposure-related early mortality. A greater than one order of magnitude difference was observed between an MIC concentration that caused no early mortality in rats (3506 ppm) and an MIC concentration that caused partial (6%) early mortality in guinea pigs (225 ppm) for exposures of 10 to 15 min duration. For both species, the most noteworthy clinical signs during exposure were lacrimation, blepharospasm, and mouth breathing. Fifteen minute LC/sub 50/ tests with 14-day postexposure follow-up were conducted, and the LC/sub 50/ (95% confidence limit) values were 171 (114-256) ppm for rats and 112 (61-204) ppm for guinea pigs. Target exposure concentrations for the toxicologic investigations of MIC-induced early mortality were established. A short summary of pertinent results of Union Carbide Corporation's post-Bhopal toxicologic investigations is presented.

  12. Phenanthrene exposure induces cardiac hypertrophy via reducing miR-133a expression by DNA methylation.

    PubMed

    Huang, Lixing; Xi, Zhihui; Wang, Chonggang; Zhang, Youyu; Yang, Zhibing; Zhang, Shiqi; Chen, Yixin; Zuo, Zhenghong

    2016-01-01

    Growing evidence indicates that there is an emerging link between environmental pollution and cardiac hypertrophy, while the mechanism is unclear. The objective of this study was to examine whether phenanthrene (Phe) could cause cardiac hypertrophy, and elucidate the molecular mechanisms involved. We found that: 1) Phe exposure increased the heart weight and cardiomyocyte size of rats; 2) Phe exposure led to enlarged cell size, and increased protein synthesis in H9C2 cells; 3) Phe exposure induced important markers of cardiac hypertrophy, such as atrial natriuretic peptide, B-type natriuretic peptide, and c-Myc in H9C2 cells and rat hearts; 4) Phe exposure perturbed miR-133a, CdC42 and RhoA, which were key regulators of cardiac hypertrophy, in H9C2 cells and rat hearts; 5) Phe exposure induced DNA methyltransferases (DNMTs) in H9C2 cells and rat hearts; 6) Phe exposure led to methylation of CpG sites within the miR-133a locus and reduced miR-133a expression in H9C2 cells; 7) DNMT inhibition and miR-133a overexpression could both alleviate the enlargement of cell size and perturbation of CdC42 and RhoA caused by Phe exposure. These results indicated that Phe could induce cardiomyocyte hypertrophy in the rat and H9C2 cells. The mechanism might involve reducing miR-133a expression by DNA methylation. PMID:26830171

  13. Phenanthrene exposure induces cardiac hypertrophy via reducing miR-133a expression by DNA methylation

    PubMed Central

    Huang, Lixing; Xi, Zhihui; Wang, Chonggang; Zhang, Youyu; Yang, Zhibing; Zhang, Shiqi; Chen, Yixin; Zuo, Zhenghong

    2016-01-01

    Growing evidence indicates that there is an emerging link between environmental pollution and cardiac hypertrophy, while the mechanism is unclear. The objective of this study was to examine whether phenanthrene (Phe) could cause cardiac hypertrophy, and elucidate the molecular mechanisms involved. We found that: 1) Phe exposure increased the heart weight and cardiomyocyte size of rats; 2) Phe exposure led to enlarged cell size, and increased protein synthesis in H9C2 cells; 3) Phe exposure induced important markers of cardiac hypertrophy, such as atrial natriuretic peptide, B-type natriuretic peptide, and c-Myc in H9C2 cells and rat hearts; 4) Phe exposure perturbed miR-133a, CdC42 and RhoA, which were key regulators of cardiac hypertrophy, in H9C2 cells and rat hearts; 5) Phe exposure induced DNA methyltransferases (DNMTs) in H9C2 cells and rat hearts; 6) Phe exposure led to methylation of CpG sites within the miR-133a locus and reduced miR-133a expression in H9C2 cells; 7) DNMT inhibition and miR-133a overexpression could both alleviate the enlargement of cell size and perturbation of CdC42 and RhoA caused by Phe exposure. These results indicated that Phe could induce cardiomyocyte hypertrophy in the rat and H9C2 cells. The mechanism might involve reducing miR-133a expression by DNA methylation. PMID:26830171

  14. Associations between antibiotic exposure during pregnancy, birth weight and aberrant methylation at imprinted genes among offspring

    PubMed Central

    Vidal, A C; Murphy, S K; Murtha, A P; Schildkraut, J M; Soubry, A; Huang, Z; Neelon, S E B; Fuemmeler, B; Iversen, E; Wang, F; Kurtzberg, J; Jirtle, R L; Hoyo, C

    2013-01-01

    Objectives: Low birth weight (LBW) has been associated with common adult-onset chronic diseases, including obesity, cardiovascular disease, type II diabetes and some cancers. The etiology of LBW is multi-factorial. However, recent evidence suggests exposure to antibiotics may also increase the risk of LBW. The mechanisms underlying this association are unknown, although epigenetic mechanisms are hypothesized. In this study, we evaluated the association between maternal antibiotic use and LBW and examined the potential role of altered DNA methylation that controls growth regulatory imprinted genes in these associations. Methods: Between 2009–2011, 397 pregnant women were enrolled and followed until delivery. Prenatal antibiotic use was ascertained through maternal self-report. Imprinted genes methylation levels were measured at differentially methylated regions (DMRs) using bisulfite pyrosequencing. Generalized linear models were used to examine associations among antibiotic use, birth weight and DMR methylation fractions. Results: After adjusting for infant gender, race/ethnicity, maternal body mass index, delivery route, gestational weight gain, gestational age at delivery, folic acid intake, physical activity, maternal smoking and parity, antibiotic use during pregnancy was associated with 138 g lower birth weight compared with non-antibiotic use (β-coefficient=−132.99, s.e.=50.70, P=0.008). These associations were strongest in newborns of women who reported antibiotic use other than penicillins (β-coefficient=−135.57, s.e.=57.38, P=0.02). Methylation at five DMRs, IGF2 (P=0.05), H19 (P=0.15), PLAGL1 (P=0.01), MEG3 (P=0.006) and PEG3 (P=0.08), was associated with maternal antibiotic use; among these, only methylation at the PLAGL1 DMR was also associated with birth weight. Conclusion: We report an inverse association between in utero exposure to antibiotics and lower infant birth weight and provide the first empirical evidence supporting imprinted gene

  15. Effects of Low-Dose Diethylstilbestrol Exposure on DNA Methylation in Mouse Spermatocytes

    PubMed Central

    Yin, Li; Zheng, Li-juan; Jiang, Xiao; Liu, Wen-bin; Han, Fei; Cao, Jia; Liu, Jin-yi

    2015-01-01

    Evidence from previous studies suggests that the male reproductive system can be disrupted by fetal or neonatal exposure to diethylstilbestrol (DES). However, the molecular basis for this effect remains unclear. To evaluate the effects of DES on mouse spermatocytes and to explore its potential mechanism of action, the levels of DNA methyltransferases (DNMTs) and DNA methylation induced by DES were detected. The results showed that low doses of DES inhibited cell proliferation and cell cycle progression and induced apoptosis in GC-2 cells, an immortalized mouse pachytene spermatocyte-derived cell line, which reproduces primary cells responses to E2. Furthermore, global DNA methylation levels were increased and the expression levels of DNMTs were altered in DES-treated GC-2 cells. A total of 141 differentially methylated DNA sites were detected by microarray analysis. Rxra, an important component of the retinoic acid signaling pathway, and mybph, a RhoA pathway-related protein, were found to be hypermethylated, and Prkcd, an apoptosis-related protein, was hypomethylated. These results showed that low-dose DES was toxic to spermatocytes and that DNMT expression and DNA methylation were altered in DES-exposed cells. Taken together, these data demonstrate that DNA methylation likely plays an important role in mediating DES-induced spermatocyte toxicity in vitro. PMID:26588706

  16. Prenatal exposure to allergen, DNA methylation, and allergy in grandoffspring mice

    PubMed Central

    Niedzwiecki, M.; Zhu, H.; Corson, L.; Grunig, G.; Factor, P. H.; Chu, S.; Jiang, H.; Miller, R. L.

    2012-01-01

    Background Prenatal allergen exposure has been linked to both induction and protection of allergic sensitization in offspring. We hypothesized that prenatal exposure of mice (F0) to Aspergillus fumigatus (A. fumigatus) would be associated with decreased immunoglobulin (Ig) E and airway eosinophilia and alterations in CpG methylation of T-helper genes in third-generation mice (F2). Methods Female BALB/c mice were sensitized to A. fumigatus (62.5, 125, 1250 μg, or saline) and re-exposed to the same dose on days 7 and 14 (early) or days 12 and 17 (late) gestation. Grandoffspring were treated with A. fumigatus (62.5 μg) at 9 weeks. IgE, IgG1, and IgG2a levels and cell counts from bronchoalveolar lavage fluid were determined. Lung DNA was pyrosequenced at multiple sites in the interferon (IFN)-γ and interleukin (IL)-4 promoters. Results Grandoffspring of mothers dosed with 1250 μg early during pregnancy developed increased airway eosinophilia (P < 0.05). Grandoffspring of mothers dosed late in pregnancy developed lower IgE (P < 0.05) and airway eosinophilia (P < 0.05). Grandoffspring of mothers dosed early had lower methylation at IL-4 CpG−408 and CpG−393 compared to late dosed mice (P < 0.005 across all doses). Few correlations were found between methylation levels and airway eosinophilia and IgE. Conclusion Prenatal exposure to A. fumigatus late during pregnancy, but not early, was associated with lower IgE and airway eosinophilia in grandoffspring. Prenatal exposure to A. fumigatus was associated with changes in CpG methylation in the IFN-γ and IL-4 promoters that did not correlate consistently with indicators of allergic sensitization. PMID:22583153

  17. Lead Exposure during Early Human Development and DNA Methylation of Imprinted Gene Regulatory Elements in Adulthood

    PubMed Central

    Li, Yue; Xie, Changchun; Murphy, Susan K.; Skaar, David; Nye, Monica; Vidal, Adriana C.; Cecil, Kim M.; Dietrich, Kim N.; Puga, Alvaro; Jirtle, Randy L.; Hoyo, Cathrine

    2015-01-01

    Background: Lead exposure during early development causes neurodevelopmental disorders by unknown mechanisms. Epidemiologic studies have focused recently on determining associations between lead exposure and global DNA methylation; however, such approaches preclude the identification of loci that may alter human disease risk. Objectives: The objective of this study was to determine whether maternal, postnatal, and early childhood lead exposure can alter the differentially methylated regions (DMRs) that control the monoallelic expression of imprinted genes involved in metabolism, growth, and development. Methods: Questionnaire data and serial blood lead levels were obtained from 105 participants (64 females, 41 males) of the Cincinnati Lead Study from birth to 78 months. When participants were adults, we used Sequenom EpiTYPER assays to test peripheral blood DNA to quantify CpG methylation in peripheral blood leukocytes at DMRs of 22 human imprinted genes. Statistical analyses were conducted using linear regression. Results: Mean blood lead concentration from birth to 78 months was associated with a significant decrease in PEG3 DMR methylation (β = –0.0014; 95% CI: –0.0023, –0.0005, p = 0.002), stronger in males (β = –0.0024; 95% CI: –0.0038, –0.0009, p = 0.003) than in females (β = –0.0009; 95% CI: –0.0020, 0.0003, p = 0.1). Elevated mean childhood blood lead concentration was also associated with a significant decrease in IGF2/H19 (β = –0.0013; 95% CI: –0.0023, –0.0003, p = 0.01) DMR methylation, but primarily in females, (β = –0.0017; 95% CI: –0.0029, –0.0006, p = 0.005) rather than in males, (β = –0.0004; 95% CI: –0.0023, 0.0015, p = 0.7). Elevated blood lead concentration during the neonatal period was associated with higher PLAGL1/HYMAI DMR methylation regardless of sex (β = 0.0075; 95% CI: 0.0018, 0.0132, p = 0.01). The magnitude of associations between cumulative lead exposure and CpG methylation remained unaltered from

  18. Multigenerational epigenetic inheritance in humans: DNA methylation changes associated with maternal exposure to lead can be transmitted to the grandchildren

    PubMed Central

    Sen, Arko; Heredia, Nicole; Senut, Marie-Claude; Land, Susan; Hollocher, Kurt; Lu, Xiangyi; Dereski, Mary O.; Ruden, Douglas M.

    2015-01-01

    We report that the DNA methylation profile of a child’s neonatal whole blood can be significantly influenced by his or her mother’s neonatal blood lead levels (BLL). We recruited 35 mother-infant pairs in Detroit and measured the whole blood lead (Pb) levels and DNA methylation levels at over 450,000 loci from current blood and neonatal blood from both the mother and the child. We found that mothers with high neonatal BLL correlate with altered DNA methylation at 564 loci in their children’s neonatal blood. Our results suggest that Pb exposure during pregnancy affects the DNA methylation status of the fetal germ cells, which leads to altered DNA methylation in grandchildren’s neonatal dried blood spots. This is the first demonstration that an environmental exposure in pregnant mothers can have an epigenetic effect on the DNA methylation pattern in the grandchildren. PMID:26417717

  19. Third trimester phthalate exposure is associated with DNA methylation of growth-related genes in human placenta

    PubMed Central

    Zhao, Yan; Chen, Jiao; Wang, Xiu; Song, Qi; Xu, Hui-Hui; Zhang, Yun-Hui

    2016-01-01

    Strong evidence implicates maternal phthalate exposure during pregnancy in contributing to adverse birth outcomes. Recent research suggests these effects might be mediated through the improper regulation of DNA methylation in offspring tissue. In this study, we examined associations between prenatal phthalate exposure and DNA methylation in human placenta. We recruited 181 mother-newborn pairs (80 fetal growth restriction newborns, 101 normal newborns) in Wenzhou, China and measured third trimester urinary phthalate metabolite concentrations and placental DNA methylation levels of IGF2 and AHRR. We found urinary concentrations of mono (2-ethyl-5- hydroxyhexyl) phthalate (MEHHP), and mono (2-ethyl-5-oxohexyl) phthalate (MEOHP) were significantly inversely associated with placental IGF2 DNA methylation. The associations were much more evident in fetal growth restriction (FGR) newborns than those in normal newborns. These findings suggest that changes in placental DNA methylation might be part of the underlying biological pathway between prenatal phthalate exposure and adverse fetal growth. PMID:27653773

  20. Third trimester phthalate exposure is associated with DNA methylation of growth-related genes in human placenta

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Chen, Jiao; Wang, Xiu; Song, Qi; Xu, Hui-Hui; Zhang, Yun-Hui

    2016-09-01

    Strong evidence implicates maternal phthalate exposure during pregnancy in contributing to adverse birth outcomes. Recent research suggests these effects might be mediated through the improper regulation of DNA methylation in offspring tissue. In this study, we examined associations between prenatal phthalate exposure and DNA methylation in human placenta. We recruited 181 mother-newborn pairs (80 fetal growth restriction newborns, 101 normal newborns) in Wenzhou, China and measured third trimester urinary phthalate metabolite concentrations and placental DNA methylation levels of IGF2 and AHRR. We found urinary concentrations of mono (2-ethyl-5- hydroxyhexyl) phthalate (MEHHP), and mono (2-ethyl-5-oxohexyl) phthalate (MEOHP) were significantly inversely associated with placental IGF2 DNA methylation. The associations were much more evident in fetal growth restriction (FGR) newborns than those in normal newborns. These findings suggest that changes in placental DNA methylation might be part of the underlying biological pathway between prenatal phthalate exposure and adverse fetal growth.

  1. Biomonitoring of exposure to N-methyl-2-pyrrolidone in workers of the automobile industry.

    PubMed

    Meier, Swetlana; Schindler, Birgit K; Koslitz, Stephan; Koch, Holger M; Weiss, Tobias; Käfferlein, Heiko U; Brüning, Thomas

    2013-07-01

    N-methyl-2-pyrrolidone (NMP) is an important organic solvent for varnishes in industry. NMP has been previously shown to be a developmental toxicant in rodents. This study reports current exposures to NMP in the spraying department of an automobile plant using biological monitoring. Two specific metabolites, 5-hydroxy-N-methyl-2-pyrrolidone (5-HNMP) and 2-hydroxy-N-methyl-succinimide (2-HMSI), were analyzed in 69 urine samples of 14 workers exposed to NMP and 9 nonexposed controls. Three different working tasks ('loading' and 'cleaning' of the sprayer system and 'wiping/packing' of the sprayed materials) and three sampling times (preshift, postshift, and preshift of the following day) were studied in exposed workers. Median exposures of 5-HNMP and 2-HMSI in postshift urine of exposed workers were 0.91 and 0.52mg g(-1) creatinine, respectively, whereas median levels in controls were below the limit of detection. Decreased levels of 5-HNMP were observed in preshift urine samples on the following day (0.39mg g(-1) creatinine) in exposed workers, while the concentration of 2-HMSI did not change (0.49mg g(-1) creatinine). Highest exposures occurred during sprayer cleaning with a maximum level of 8.31mg g(-1) creatinine of 5-HNMP in postshift urine. In contrast to 'wipers/packers', no decrease in 5-HNMP could be observed in preshift urine samples on day 2 of the 'loaders' and 'cleaners'. Overall, exposure in terms of 5-HNMP postshift and 2-HMSI preshift of the following day were well below the current biological limit values of the European Union (70 and 20mg g(-1) creatinine). Our results provide initial data on NMP exposure in the automobile industry and suggest that the analysis of 5-HNMP in preshift samples also provides essential information, particularly in situations involving direct handling of liquid NMP-containing formulations.

  2. Prenatal exposures and DNA methylation in newborns: a pilot study in Durban, South Africa.

    PubMed

    Goodrich, Jaclyn M; Reddy, Poovendhree; Naidoo, Rajen N; Asharam, Kareshma; Batterman, Stuart; Dolinoy, Dana C

    2016-07-13

    The in utero environment has the potential to influence epigenetic programming and subsequently the health of offspring. Even though pregnant women living in urban Africa are exposed to multiple chemicals and infectious agents that may impact their developing children, the neonatal epigenome has not been studied in these regions. We assessed whether prenatal exposures to air pollution and maternal human immunodeficiency virus (HIV) are associated with changes to DNA methylation throughout the epigenome using a pilot sample from the Mother and Child Environmental (MACE) birth cohort, of which 36% of the mothers are HIV positive. Families living in a high air pollution region (south Durban, n = 11) and a low air pollution region (north Durban, n = 11) with comparable socioeconomic characteristics were selected for analysis. DNA methylation was quantified in cord blood plasma DNA at >430 000 CpG sites using the Infinium HumanMethylation450 BeadChip. Sites associated with living in south Durban or maternal HIV infection (p < 0.001) were more likely to be hypomethylated and located in CpG islands. Top differentially methylated sites by region of Durban were enriched in pathways related to xenobiotic metabolism, oxygen and gas transport, and sensory perception of chemical stimuli when performing gene set enrichment testing with LRpath. Differentially methylated sites by maternal HIV status were enriched in cytochrome P450s, pathways involved in detection of chemical stimuli, metabolic processes, and viral regulation and processing. Given the small sample size of the study, future work examining the impact of prenatal exposures to air pollution, maternal infection, and antiviral treatment on the epigenome and downstream health implications is merited in Sub-Saharan African populations. PMID:27359112

  3. Zebrafish embryos as a screen for DNA methylation modifications after compound exposure.

    PubMed

    Bouwmeester, Manon C; Ruiter, Sander; Lommelaars, Tobias; Sippel, Josefine; Hodemaekers, Hennie M; van den Brandhof, Evert-Jan; Pennings, Jeroen L A; Kamstra, Jorke H; Jelinek, Jaroslav; Issa, Jean-Pierre J; Legler, Juliette; van der Ven, Leo T M

    2016-01-15

    Modified epigenetic programming early in life is proposed to underlie the development of an adverse adult phenotype, known as the Developmental Origins of Health and Disease (DOHaD) concept. Several environmental contaminants have been implicated as modifying factors of the developing epigenome. This underlines the need to investigate this newly recognized toxicological risk and systematically screen for the epigenome modifying potential of compounds. In this study, we examined the applicability of the zebrafish embryo as a screening model for DNA methylation modifications. Embryos were exposed from 0 to 72 h post fertilization (hpf) to bisphenol-A (BPA), diethylstilbestrol, 17α-ethynylestradiol, nickel, cadmium, tributyltin, arsenite, perfluoroctanoic acid, valproic acid, flusilazole, 5-azacytidine (5AC) in subtoxic concentrations. Both global and site-specific methylation was examined. Global methylation was only affected by 5AC. Genome wide locus-specific analysis was performed for BPA exposed embryos using Digital Restriction Enzyme Analysis of Methylation (DREAM), which showed minimal wide scale effects on the genome, whereas potential informative markers were not confirmed by pyrosequencing. Site-specific methylation was examined in the promoter regions of three selected genes vasa, vtg1 and cyp19a2, of which vasa (ddx4) was the most responsive. This analysis distinguished estrogenic compounds from metals by direction and sensitivity of the effect compared to embryotoxicity. In conclusion, the zebrafish embryo is a potential screening tool to examine DNA methylation modifications after xenobiotic exposure. The next step is to examine the adult phenotype of exposed embryos and to analyze molecular mechanisms that potentially link epigenetic effects and altered phenotypes, to support the DOHaD hypothesis.

  4. Zebrafish embryos as a screen for DNA methylation modifications after compound exposure.

    PubMed

    Bouwmeester, Manon C; Ruiter, Sander; Lommelaars, Tobias; Sippel, Josefine; Hodemaekers, Hennie M; van den Brandhof, Evert-Jan; Pennings, Jeroen L A; Kamstra, Jorke H; Jelinek, Jaroslav; Issa, Jean-Pierre J; Legler, Juliette; van der Ven, Leo T M

    2016-01-15

    Modified epigenetic programming early in life is proposed to underlie the development of an adverse adult phenotype, known as the Developmental Origins of Health and Disease (DOHaD) concept. Several environmental contaminants have been implicated as modifying factors of the developing epigenome. This underlines the need to investigate this newly recognized toxicological risk and systematically screen for the epigenome modifying potential of compounds. In this study, we examined the applicability of the zebrafish embryo as a screening model for DNA methylation modifications. Embryos were exposed from 0 to 72 h post fertilization (hpf) to bisphenol-A (BPA), diethylstilbestrol, 17α-ethynylestradiol, nickel, cadmium, tributyltin, arsenite, perfluoroctanoic acid, valproic acid, flusilazole, 5-azacytidine (5AC) in subtoxic concentrations. Both global and site-specific methylation was examined. Global methylation was only affected by 5AC. Genome wide locus-specific analysis was performed for BPA exposed embryos using Digital Restriction Enzyme Analysis of Methylation (DREAM), which showed minimal wide scale effects on the genome, whereas potential informative markers were not confirmed by pyrosequencing. Site-specific methylation was examined in the promoter regions of three selected genes vasa, vtg1 and cyp19a2, of which vasa (ddx4) was the most responsive. This analysis distinguished estrogenic compounds from metals by direction and sensitivity of the effect compared to embryotoxicity. In conclusion, the zebrafish embryo is a potential screening tool to examine DNA methylation modifications after xenobiotic exposure. The next step is to examine the adult phenotype of exposed embryos and to analyze molecular mechanisms that potentially link epigenetic effects and altered phenotypes, to support the DOHaD hypothesis. PMID:26712470

  5. Crystal structure of 2,6-bis-(2-hy-droxy-5-methyl-phen-yl)-4-phenyl-pyridinium bromide di-chloro-methane hemisolvate hemihydrate.

    PubMed

    Mankaev, Badma N; Zaitsev, Kirill V; Karlov, Sergey S; Egorov, Mikhail P; Churakov, Andrei V

    2015-12-01

    The asymmetric unit in the structure of the title compound, C25H22NO2 (+)·Br (-)·0.5CH2Cl2·0.5H2O, comprises two pseudosymmetry-related cations, two bromide anions, a di-chloro-methane molecule and a water mol-ecule of solvation. The two independent cations are conformationally similar with the comparative dihedral angles between the central pyridine ring and the three benzene substituent rings being 3.0 (2), 36.4 (1) and 24.2 (1)°, and 3.7 (2), 36.5 (1) and 24.8 (1)°, respectively. In the crystal, the cations, anions and water mol-ecules are linked through O-H⋯O and O-H⋯Br hydrogen bonds, forming an insular unit. Within the cations there are also intra-molecular N-H⋯O hydrogen bonds. Adjacent centrosymmetrically related aggregates are linked by π-π stacking inter-actions between the pyridine ring and a benzene ring in both cations [ring-centroid separations = 3.525 (3) and 3.668 (3) Å], forming chains extending across the ac diagonal. Voids between these chains are filled by dichloromethane molecules. PMID:26870547

  6. Influence of developmental lead exposure on expression of DNA methyltransferases and methyl cytosine-binding proteins in hippocampus.

    PubMed

    Schneider, J S; Kidd, S K; Anderson, D W

    2013-02-13

    Developmental exposure to lead (Pb) has adverse effects on cognitive functioning and behavior that can persist into adulthood. Exposures that occur during fetal or early life periods may produce changes in brain related to physiological re-programming from an epigenetic influence such as altered DNA methylation status. Since DNA methylation is regulated by DNA methyltransferases and methyl cytosine-binding proteins, this study assessed the extent to which developmental Pb exposure might affect expression of these proteins in the hippocampus. Long Evans dams were fed chow with or without added Pb acetate (0, 150, 375, 750 ppm) prior to breeding and remained on the same diet through weaning (perinatal exposure group). Other animals were exposed to the same doses of Pb but exposure started on postnatal day 1 and continued through weaning (early postnatal exposure group). All animals were euthanized on day 55 and hippocampi were removed. Western blot analyses showed significant effects of Pb exposure on DNMT1, DNMT3a, and MeCP2 expression, with effects often seen at the lowest level of exposure and modified by sex and developmental window of Pb exposure. These data suggest potential epigenetic effects of developmental Pb exposure on DNA methylation mediated at least in part through dysregulation of methyltransferases. PMID:23246732

  7. DNA methylation is differentially associated with environmental cadmium exposure based on sex and smoking status.

    PubMed

    Virani, Shama; Rentschler, Katie M; Nishijo, Muneko; Ruangyuttikarn, Werawan; Swaddiwudhipong, Witaya; Basu, Niladri; Rozek, Laura S

    2016-02-01

    The adverse health effects of cadmium (Cd) are well known in human populations; however, much of what is known about biological mechanisms of Cd comes from in vitro and animal studies. The adverse health outcomes due to high levels of Cd exposure in the population of Mae Sot, Thailand have been extensively characterized. Here, for the first time, this population is being studied in an epigenetic context. The objective of this study was to characterize the association between DNA methylation markers and Cd exposure, taking into account sex and smoking differences, in an adult population at an increased risk of experiencing adverse health outcomes from high body burden of Cd. One hundred and sixty-nine residents from known exposure areas of Mae Sot, Thailand and one hundred residents from non-exposed areas nearby were surveyed in 2012. Urine and blood samples were collected for measurement of urinary Cd (UCd) and DNA methylation of Cd-related markers (DNMT3B, MGMT, LINE-1, MT2A). UCd levels were 7 times higher in the exposed compared to the unexposed populations (exposed median: 7.4 μg/L, unexposed median: 1.0 μg/L, p < 0.001). MGMT hypomethylation was associated with increasing levels of UCd in the total population. Sex-specific associations included MT2A and DNMT3B hypomethylation in women and LINE-1 hypermethylation in men with increasing UCd. Upon subanalysis, these associations separated by smoking status. In summary, environmental Cd exposure is associated with gene-specific DNA methylation in a sex and smoking dependent manner.

  8. Self-Assembly of Oleyl Bis(2-hydroxyethyl)methyl Ammonium Bromide with Sodium Dodecyl Sulfate and Their Interactions with Zein.

    PubMed

    Chen, Yao; Ji, Xiuling; Han, Yuchun; Wang, Yilin

    2016-08-16

    Surface tension and aggregation behavior in an aqueous solution of the mixture of cationic surfactant oleyl bis(2-hydroxyethyl)methylammonium bromide (OHAB) and anionic surfactant sodium dodecyl sulfate (SDS) have been studied by surface tension, conductivity, turbidity, zeta potential, isothermal titration microcalorimetry (ITC), cryogenic transmission electron microscopy (Cryo-TEM), and dynamic light scattering. The mixture shows pretty low critical micellar concentration and surface tension, and successively forms globular micelles, unilamellar vesicles, multilamellar vesicles, rod-like micelles, and globular micelles again by increasing the molar fraction of OHAB from 0 to 1.00. The cooperation of hydrophobic interaction between the alkyl chains, electrostatic attraction between the headgroups as well as hydrogen bonds between the hydroxyethyl groups leads to the abundant aggregation behaviors. Furthermore, the solubilization of zein by the OHAB/SDS aggregates and their interactions were studied by ITC, total organic carbon analysis (TOC), and Cryo-TEM. Compared with pure OHAB or pure SDS solution, the amount of zein solubilized by the OHAB/SDS mixture is significantly reduced. It means that the mixtures have much stronger abilities in solubilizing zein. This result has also been proved by the observed enthalpy changes for the interaction of OHAB/SDS mixture with zein. Mixing oppositely charged OHAB and SDS reduces the net charge of mixed aggregates, and thus, the electrostatic attraction between the aggregates and zein is weakened. Meanwhile, the large size of the aggregates may increase the steric repulsion to the zein backbone. This work reveals that surfactant mixtures with larger aggregates and smaller CMCs solubilize less zein, suggesting how to construct a highly efficient and nonirritant surfactant system for practical use. PMID:27452480

  9. Modulation of microsomal membrane associated detoxication enzymes activity by methyl isocyanate (MIC) exposure

    SciTech Connect

    Mishra, A.; Dwivedi, P.D.; Verma, A.S.; Mishra, J.; Sinha, M.; Dutta, K.K.; Ray, P.K. )

    1991-11-01

    In the industrial disaster at Bhopal, India in 1984 the leakage of 40 tons of methyl isocyanate (MIC) gas from a pesticide plant claimed over 2,500 lives and left an estimated population of 15,000 people suffering from a variety of ailments. MIC induced changes in respiratory functions including bronchial asthma, pulmonary oedema, necrosis of alveoli, hypersensitivity, pneumonities and incapacitated pulmonary functions. Reports have also indicated changes in the respiratory tract of animals as a result of exposure to MIC, the lung being the main target organ attacked by MIC. The authors earlier report of the high dose single exposure toxicity to methyl isocyanate leads to alterations in biotransformation enzymes and their isoenzymic pattern. Recently, a drastic decrease in Na{sup +}, K{sup +}, and Mg{sup ++} ATPase enzyme levels by repeated MIC exposure has been shown. The present study further explores the biochemical basis of MIC intoxication with reference to consecutive dose dependent toxicity in terms of alteration in phase 1 and phase 2 membrane bound detoxication enzymes.

  10. (BOSC) DOSE-RESPONSE MODELING FOR THE ASSESSMENT OF CUMULATIVE RISK DUE TO EXPOSURE TO N-METHYL CARBAMATE PRESTICIDES

    EPA Science Inventory

    THE US EPA'S N-METHYL CARBAMATE CUMULATIVE RISK ASSESSMENT (NMCRA) ASSESSES THE EFFECT ON ACETYLCHOLINE ESTERASE (AChE) ACTIVITY OF EXPOSURE TO 10 N-METHLY CARBAMATE (NMC)PESTICIDES THROUGH DIETARY, DRINKING WATER, AND RESIDENTIAL EXPOSURES. THESE DATA THUS INFORM, BUT DO NOT COM...

  11. Quality control and statistical modeling for environmental epigenetics: A study on in utero lead exposure and DNA methylation at birth

    PubMed Central

    Goodrich, Jaclyn M; Sánchez, Brisa N; Dolinoy, Dana C; Zhang, Zhenzhen; Hernández-Ávila, Mauricio; Hu, Howard; Peterson, Karen E; Téllez-Rojo, Martha M

    2015-01-01

    DNA methylation data assayed using pyrosequencing techniques are increasingly being used in human cohort studies to investigate associations between epigenetic modifications at candidate genes and exposures to environmental toxicants and to examine environmentally-induced epigenetic alterations as a mechanism underlying observed toxicant-health outcome associations. For instance, in utero lead (Pb) exposure is a neurodevelopmental toxicant of global concern that has also been linked to altered growth in human epidemiological cohorts; a potential mechanism of this association is through alteration of DNA methylation (e.g., at growth-related genes). However, because the associations between toxicants and DNA methylation might be weak, using appropriate quality control and statistical methods is important to increase reliability and power of such studies. Using a simulation study, we compared potential approaches to estimate toxicant-DNA methylation associations that varied by how methylation data were analyzed (repeated measures vs. averaging all CpG sites) and by method to adjust for batch effects (batch controls vs. random effects). We demonstrate that correcting for batch effects using plate controls yields unbiased associations, and that explicitly modeling the CpG site-specific variances and correlations among CpG sites increases statistical power. Using the recommended approaches, we examined the association between DNA methylation (in LINE-1 and growth related genes IGF2, H19 and HSD11B2) and 3 biomarkers of Pb exposure (Pb concentrations in umbilical cord blood, maternal tibia, and maternal patella), among mother-infant pairs of the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) cohort (n = 247). Those with 10 μg/g higher patella Pb had, on average, 0.61% higher IGF2 methylation (P = 0.05). Sex-specific trends between Pb and DNA methylation (P < 0.1) were observed among girls including a 0.23% increase in HSD11B2 methylation with 10

  12. Quality control and statistical modeling for environmental epigenetics: a study on in utero lead exposure and DNA methylation at birth.

    PubMed

    Goodrich, Jaclyn M; Sánchez, Brisa N; Dolinoy, Dana C; Zhang, Zhenzhen; Hernández-Ávila, Mauricio; Hu, Howard; Peterson, Karen E; Téllez-Rojo, Martha M

    2015-01-01

    DNA methylation data assayed using pyrosequencing techniques are increasingly being used in human cohort studies to investigate associations between epigenetic modifications at candidate genes and exposures to environmental toxicants and to examine environmentally-induced epigenetic alterations as a mechanism underlying observed toxicant-health outcome associations. For instance, in utero lead (Pb) exposure is a neurodevelopmental toxicant of global concern that has also been linked to altered growth in human epidemiological cohorts; a potential mechanism of this association is through alteration of DNA methylation (e.g., at growth-related genes). However, because the associations between toxicants and DNA methylation might be weak, using appropriate quality control and statistical methods is important to increase reliability and power of such studies. Using a simulation study, we compared potential approaches to estimate toxicant-DNA methylation associations that varied by how methylation data were analyzed (repeated measures vs. averaging all CpG sites) and by method to adjust for batch effects (batch controls vs. random effects). We demonstrate that correcting for batch effects using plate controls yields unbiased associations, and that explicitly modeling the CpG site-specific variances and correlations among CpG sites increases statistical power. Using the recommended approaches, we examined the association between DNA methylation (in LINE-1 and growth related genes IGF2, H19 and HSD11B2) and 3 biomarkers of Pb exposure (Pb concentrations in umbilical cord blood, maternal tibia, and maternal patella), among mother-infant pairs of the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) cohort (n = 247). Those with 10 μg/g higher patella Pb had, on average, 0.61% higher IGF2 methylation (P = 0.05). Sex-specific trends between Pb and DNA methylation (P < 0.1) were observed among girls including a 0.23% increase in HSD11B2 methylation with 10

  13. Quality control and statistical modeling for environmental epigenetics: a study on in utero lead exposure and DNA methylation at birth.

    PubMed

    Goodrich, Jaclyn M; Sánchez, Brisa N; Dolinoy, Dana C; Zhang, Zhenzhen; Hernández-Ávila, Mauricio; Hu, Howard; Peterson, Karen E; Téllez-Rojo, Martha M

    2015-01-01

    DNA methylation data assayed using pyrosequencing techniques are increasingly being used in human cohort studies to investigate associations between epigenetic modifications at candidate genes and exposures to environmental toxicants and to examine environmentally-induced epigenetic alterations as a mechanism underlying observed toxicant-health outcome associations. For instance, in utero lead (Pb) exposure is a neurodevelopmental toxicant of global concern that has also been linked to altered growth in human epidemiological cohorts; a potential mechanism of this association is through alteration of DNA methylation (e.g., at growth-related genes). However, because the associations between toxicants and DNA methylation might be weak, using appropriate quality control and statistical methods is important to increase reliability and power of such studies. Using a simulation study, we compared potential approaches to estimate toxicant-DNA methylation associations that varied by how methylation data were analyzed (repeated measures vs. averaging all CpG sites) and by method to adjust for batch effects (batch controls vs. random effects). We demonstrate that correcting for batch effects using plate controls yields unbiased associations, and that explicitly modeling the CpG site-specific variances and correlations among CpG sites increases statistical power. Using the recommended approaches, we examined the association between DNA methylation (in LINE-1 and growth related genes IGF2, H19 and HSD11B2) and 3 biomarkers of Pb exposure (Pb concentrations in umbilical cord blood, maternal tibia, and maternal patella), among mother-infant pairs of the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) cohort (n = 247). Those with 10 μg/g higher patella Pb had, on average, 0.61% higher IGF2 methylation (P = 0.05). Sex-specific trends between Pb and DNA methylation (P < 0.1) were observed among girls including a 0.23% increase in HSD11B2 methylation with 10

  14. Metabolic Programming of MEST DNA Methylation by Intrauterine Exposure to Gestational Diabetes Mellitus

    PubMed Central

    El Hajj, Nady; Pliushch, Galyna; Schneider, Eberhard; Dittrich, Marcus; Müller, Tobias; Korenkov, Michael; Aretz, Melanie; Zechner, Ulrich; Lehnen, Harald; Haaf, Thomas

    2013-01-01

    Epigenetic processes are primary candidates when searching for mechanisms that can stably modulate gene expression and metabolic pathways according to early life conditions. To test the effects of gestational diabetes mellitus (GDM) on the epigenome of the next generation, cord blood and placenta tissue were obtained from 88 newborns of mothers with dietetically treated GDM, 98 with insulin-dependent GDM, and 65 without GDM. Bisulfite pyrosequencing was used to compare the methylation levels of seven imprinted genes involved in prenatal and postnatal growth, four genes involved in energy metabolism, one anti-inflammatory gene, one tumor suppressor gene, one pluripotency gene, and two repetitive DNA families. The maternally imprinted MEST gene, the nonimprinted glucocorticoid receptor NR3C1 gene, and interspersed ALU repeats showed significantly decreased methylation levels (4–7 percentage points for MEST, 1–2 for NR3C1, and one for ALUs) in both GDM groups, compared with controls, in both analyzed tissues. Significantly decreased blood MEST methylation (3 percentage points) also was observed in adults with morbid obesity compared with normal-weight controls. Our results support the idea that intrauterine exposure to GDM has long-lasting effects on the epigenome of the offspring. Specifically, epigenetic malprogramming of MEST may contribute to obesity predisposition throughout life. PMID:23209187

  15. Sex-specific effects of early life cadmium exposure on DNA methylation and implications for birth weight

    PubMed Central

    Kippler, Maria; Engström, Karin; Mlakar, Simona Jurkovic; Bottai, Matteo; Ahmed, Sultan; Hossain, Mohammad Bakhtiar; Raqib, Rubhana; Vahter, Marie; Broberg, Karin

    2013-01-01

    Dietary cadmium exposure was recently found to alter DNA methylation in adults, but data on effects early in life are lacking. Our objective was to evaluate associations between prenatal cadmium exposure, DNA methylation and birth weight. In total 127 mother-child pairs from rural Bangladesh were studied. For comparison, we included 56 children at 4.5 y. Cadmium concentrations in mothers’ blood (gestational week 14) and children’s urine were measured by ICPMS. Global DNA methylation was analyzed by Infinium HumanMethylation450K BeadChip in cord blood and children’s blood. Maternal cadmium exposure was associated with cord blood DNA methylation (p-value < 10–16). The association was markedly sex-specific. In boys, 96% of the top 500 CpG sites showed positive correlations (rS-values > 0.50), whereas most associations in girls were inverse; only 29% were positive (rS > 0.45). In girls we found overrepresentation of methylation changes in genes associated with organ development, morphology and mineralization of bone, whereas changes in boys were found in cell death-related genes. Several individual CpG sites that were positively associated with cadmium were inversely correlated with birth weight, although none statistically significant after correction for multiple comparisons. The associations were, however, fairly robust in multivariable-adjusted linear regression models. We identified CpG sites that were significantly associated with cadmium exposure in both newborns and 4.5-y-old children. In conclusion, cadmium exposure in early life appears to alter DNA methylation differently in girls and boys. This is consistent with previous findings of sex-specific cadmium toxicity. Cadmium-related changes in methylation were also related to lower birth weight. PMID:23644563

  16. DNA methylation levels and long-term trihalomethane exposure in drinking water: an epigenome-wide association study.

    PubMed

    Salas, Lucas A; Bustamante, Mariona; Gonzalez, Juan R; Gracia-Lavedan, Esther; Moreno, Victor; Kogevinas, Manolis; Villanueva, Cristina M

    2015-01-01

    Trihalomethanes (THM) are undesired disinfection byproducts (DBPs) formed during water treatment. Mice exposed to DBPs showed global DNA hypomethylation and c-myc and c-jun gene-specific hypomethylation, while evidence of epigenetic effects in humans is scarce. We explored the association between lifetime THM exposure and DNA methylation through an epigenome-wide association study. We selected 138 population-based controls from a case-control study of colorectal cancer conducted in Barcelona, Spain, exposed to average lifetime THM levels ≤85 μg/L vs. >85 μg/L (N = 68 and N = 70, respectively). Mean age of participants was 70 years, and 54% were male. Average lifetime THM level in the exposure groups was 64 and 130 µg/L, respectively. DNA was extracted from whole blood and was bisulphite converted to measure DNA methylation levels using the Illumina HumanMethylation450 BeadChip. Data preprocessing was performed using RnBeads. Methylation was compared between exposure groups using empirical Bayes moderated linear regression for CpG sites and Gaussian kernel for CpG regions. ConsensusPathDB was used for gene set enrichment. Statistically significant differences in methylation between exposure groups was found in 140 CpG sites and 30 gene-related regions, after false discovery rate <0.05 and adjustment for age, sex, methylation first principal component, and blood cell proportion. The annotated genes were localized to several cancer pathways. Among them, 29 CpGs had methylation levels associated with THM levels (|Δβ|≥0.05) located in 11 genes associated with cancer in other studies. Our results suggest that THM exposure may affect DNA methylation in genes related to tumors, including colorectal and bladder cancers. Future confirmation studies are required.

  17. DNA methylation levels and long-term trihalomethane exposure in drinking water: an epigenome-wide association study

    PubMed Central

    Salas, Lucas A; Bustamante, Mariona; Gonzalez, Juan R; Gracia-Lavedan, Esther; Moreno, Victor; Kogevinas, Manolis; Villanueva, Cristina M

    2015-01-01

    Trihalomethanes (THM) are undesired disinfection byproducts (DBPs) formed during water treatment. Mice exposed to DBPs showed global DNA hypomethylation and c-myc and c-jun gene-specific hypomethylation, while evidence of epigenetic effects in humans is scarce. We explored the association between lifetime THM exposure and DNA methylation through an epigenome-wide association study. We selected 138 population-based controls from a case-control study of colorectal cancer conducted in Barcelona, Spain, exposed to average lifetime THM levels ≤85 μg/L vs. >85 μg/L (N = 68 and N = 70, respectively). Mean age of participants was 70 years, and 54% were male. Average lifetime THM level in the exposure groups was 64 and 130 µg/L, respectively. DNA was extracted from whole blood and was bisulphite converted to measure DNA methylation levels using the Illumina HumanMethylation450 BeadChip. Data preprocessing was performed using RnBeads. Methylation was compared between exposure groups using empirical Bayes moderated linear regression for CpG sites and Gaussian kernel for CpG regions. ConsensusPathDB was used for gene set enrichment. Statistically significant differences in methylation between exposure groups was found in 140 CpG sites and 30 gene-related regions, after false discovery rate <0.05 and adjustment for age, sex, methylation first principal component, and blood cell proportion. The annotated genes were localized to several cancer pathways. Among them, 29 CpGs had methylation levels associated with THM levels (|Δβ|≥0.05) located in 11 genes associated with cancer in other studies. Our results suggest that THM exposure may affect DNA methylation in genes related to tumors, including colorectal and bladder cancers. Future confirmation studies are required. PMID:26039576

  18. Arsenic Exposure From Drinking Water, Arsenic Methylation Capacity, and Carotid Intima-Media Thickness in Bangladesh

    PubMed Central

    Chen, Yu; Wu, Fen; Graziano, Joseph H.; Parvez, Faruque; Liu, Mengling; Paul, Rina Rani; Shaheen, Ishrat; Sarwar, Golam; Ahmed, Alauddin; Islam, Tariqul; Slavkovich, Vesna; Rundek, Tatjana; Demmer, Ryan T.; Desvarieux, Moise; Ahsan, Habibul

    2013-01-01

    We conducted a cross-sectional study to evaluate the interrelationships between past arsenic exposure, biomarkers specific for susceptibility to arsenic exposure, and carotid intima-media thickness (cIMT) in 959 subjects from the Health Effects of Arsenic Longitudinal Study in Bangladesh. We measured cIMT levels on average 7.2 years after baseline during 2010–2011. Arsenic exposure was measured in well water at baseline and in urine samples collected at baseline and during follow-up. Every 1-standard-deviation increase in urinary arsenic (357.9 µg/g creatinine) and well-water arsenic (102.0 µg/L) concentration was related to a 11.7-µm (95% confidence interval (CI): 1.8, 21.6) and 5.1-µm (95% CI: −0.2, 10.3) increase in cIMT, respectively. For every 10% increase in monomethylarsonic acid (MMA) percentage, there was an increase of 12.1 µm (95% CI: 0.4, 23.8) in cIMT. Among participants with a higher urinary MMA percentage, a higher ratio of urinary MMA to inorganic arsenic, and a lower ratio of dimethylarsinic acid to MMA, the association between well-water arsenic and cIMT was stronger. The findings indicate an effect of past long-term arsenic exposure on cIMT, which may be potentiated by suboptimal or incomplete arsenic methylation capacity. Future prospective studies are needed to confirm the association between arsenic methylation capacity and atherosclerosis-related outcomes. PMID:23788675

  19. Arsenic exposure from drinking water, arsenic methylation capacity, and carotid intima-media thickness in Bangladesh.

    PubMed

    Chen, Yu; Wu, Fen; Graziano, Joseph H; Parvez, Faruque; Liu, Mengling; Paul, Rina Rani; Shaheen, Ishrat; Sarwar, Golam; Ahmed, Alauddin; Islam, Tariqul; Slavkovich, Vesna; Rundek, Tatjana; Demmer, Ryan T; Desvarieux, Moise; Ahsan, Habibul

    2013-08-01

    We conducted a cross-sectional study to evaluate the interrelationships between past arsenic exposure, biomarkers specific for susceptibility to arsenic exposure, and carotid intima-media thickness (cIMT) in 959 subjects from the Health Effects of Arsenic Longitudinal Study in Bangladesh. We measured cIMT levels on average 7.2 years after baseline during 2010-2011. Arsenic exposure was measured in well water at baseline and in urine samples collected at baseline and during follow-up. Every 1-standard-deviation increase in urinary arsenic (357.9 µg/g creatinine) and well-water arsenic (102.0 µg/L) concentration was related to a 11.7-µm (95% confidence interval (CI): 1.8, 21.6) and 5.1-µm (95% CI: -0.2, 10.3) increase in cIMT, respectively. For every 10% increase in monomethylarsonic acid (MMA) percentage, there was an increase of 12.1 µm (95% CI: 0.4, 23.8) in cIMT. Among participants with a higher urinary MMA percentage, a higher ratio of urinary MMA to inorganic arsenic, and a lower ratio of dimethylarsinic acid to MMA, the association between well-water arsenic and cIMT was stronger. The findings indicate an effect of past long-term arsenic exposure on cIMT, which may be potentiated by suboptimal or incomplete arsenic methylation capacity. Future prospective studies are needed to confirm the association between arsenic methylation capacity and atherosclerosis-related outcomes.

  20. [Bromide encephalopathies (author's transl)].

    PubMed

    Loubrieu, G; Bourin, M; Bizière, K; Breteau, M; Autret, A

    1979-07-01

    Bromide encephalopathies are frequently reported in Northern America and Great Britain. There is no characteristic clinical pattern, the neurological symptoms are multiple, this is readily explained by the diffusion of bromide ions to all regions in the central nervous system. An accurate history (bromide intake, followed by the slow onset of digestive and neuropsychiatric symptoms) as well as an apparent hyperchloremia are of the greatest aid in suggesting the diagnosis. The incidence of this type of intoxication is greater in women over 50. The association of a salt free diet to bromide therapy favors the onset of clinical symptoms because of the competition between bromide and chloride at the choroid plexus and at the renal tubule.

  1. Neurotoxicity associated with occupational exposure to acetone, methyl ethyl ketone, and cyclohexanone.

    PubMed

    Mitran, E; Callender, T; Orha, B; Dragnea, P; Botezatu, G

    1997-01-01

    The neurotoxic effects of acetone, methyl ethyl ketone (MEK), and cyclohexanone on Romanian workers and the impact of those effects on industry environmental standards have been controversial subjects. To scientifically substantiate the standards, a study was conducted on three groups of workers to determine the changes induced by ketone solvents on the central and peripheral nervous systems. Groups of exposed workers and matched controls were studied for each solvent: acetone, 71 exposed and 86 controls from a coin printing factory; MEK, 41 exposed and 63 controls from a cable factory; and cyclohexanone, 75 exposed and 85 controls from a furniture factory. The subjects' mean age was 36 years. The mean length of exposure was 14 years. Study participants completed a questionnaire, responded to questions about alcohol consumption, submitted to a clinical examination, submitted samples for identification of biological exposure markers, and underwent motor nerve conduction velocity and neurobehavioral tests. Results showed that workers exposed to acetone were most affected in terms of human performance and evidence of neurotoxicity, followed by workers exposed to MEK and workers exposed to cyclohexanone. On the basis of the results, it was proposed that the 6-hr permissible exposure limits for acetone, MEK, and cyclohexanone be reduced to less than 500, 200, and 150 mg/m3, respectively.

  2. Lithography exposure characteristics of poly(methyl methacrylate) (PMMA) for carbon, helium and hydrogen ions

    NASA Astrophysics Data System (ADS)

    Puttaraksa, Nitipon; Norarat, Rattanaporn; Laitinen, Mikko; Sajavaara, Timo; Singkarat, Somsorn; Whitlow, Harry J.

    2012-02-01

    Poly(methyl methacrylate) is a common polymer used as a lithographic resist for all forms of particle (photon, ion and electron) beam writing. Faithful lithographic reproduction requires that the exposure dose, Θ, lies in the window Θ0⩽Θ<Θ, where Θ0 and Θ represent the clearing and cross-linking onset doses, respectively. In this work we have used the programmable proximity aperture ion beam lithography systems in Chiang Mai and Jyväskylä to determine the exposure characteristics in terms of fluence for 2 MeV protons, 3 MeV 4He and 6 MeV 12C ions, respectively. After exposure the samples were developed in 7:3 by volume propan-2-ol:de-ionised water mixture. At low fluences, where the fluence is below the clearing fluence, the exposed regions were characterised by rough regions, particularly for He with holes around the ion tracks. As the fluence (dose) increases so that the dose exceeds the clearing dose, the PMMA is uniformly removed with sharp vertical walls. When Θ exceeds the cross-linking onset fluence, the bottom of the exposed regions show undissolved PMMA.

  3. Crystal structure of bis(bis{(E)-[(6-{(E)-[(4-fluorobenzyl)imino]methyl}pyridin-2-yl)methylidene](4-fluorophenyl)amine}nickel(II)) tetra-bromide nona-hydrate.

    PubMed

    Basaran, Ismet; Rhaman, Md Mhahabubur; Powell, Douglas R; Hossain, Md Alamgir

    2015-12-01

    In the title complex, [Ni(C21H17F2N3)2]2Br4·9H2O, there are two independent metal complexes per asymmetric unit and two ligands per metal complex. The structural features (bond lengths and angles) of the two complexes are almost identical. In each complex, the nickel(II) ion is coordinated in an octa-hedral environment by six N atoms from two chelating (9E)-N-({6-[(E)-(4-fluoro-benzyl-imino)-meth-yl]pyridin-2-yl}methyl-ene)(4-fluoro-phen-yl)methanammine ligands. The Ni-N bond lengths range from 1.973 (2) to 2.169 (2) Å, while the chelate N-Ni-N angles range from 77.01 (10) to 105.89 (9)°. Additionally, there are four bromide anions and nine solvent water mol-ecules within the asymmetric unit. The water mol-ecules form a hydrogen-bonded network, displaying C-H⋯O, C-H⋯Br, O-H⋯Br, O-H⋯O and O-H⋯F inter-actions into layers parallel to (111). In each unit, the fluoro-phenyl rings of one ligand are stacked with the central ring of the other ligand via π-π inter-actions, with the closest centroid-to-plane distances being 3.445 (5), 3.636 (5), 3.397 (5) and 3.396 (5) Å. PMID:26870437

  4. Crystal structure of bis(bis{(E)-[(6-{(E)-[(4-fluorobenzyl)imino]methyl}pyridin-2-yl)methylidene](4-fluorophenyl)amine}nickel(II)) tetra­bromide nona­hydrate

    PubMed Central

    Basaran, Ismet; Rhaman, Md Mhahabubur; Powell, Douglas R.; Hossain, Md. Alamgir

    2015-01-01

    In the title complex, [Ni(C21H17F2N3)2]2Br4·9H2O, there are two independent metal complexes per asymmetric unit and two ligands per metal complex. The structural features (bond lengths and angles) of the two complexes are almost identical. In each complex, the nickel(II) ion is coordinated in an octa­hedral environment by six N atoms from two chelating (9E)-N-({6-[(E)-(4-fluoro­benzyl­imino)­meth­yl]pyridin-2-yl}methyl­ene)(4-fluoro­phen­yl)methanammine ligands. The Ni—N bond lengths range from 1.973 (2) to 2.169 (2) Å, while the chelate N—Ni—N angles range from 77.01 (10) to 105.89 (9)°. Additionally, there are four bromide anions and nine solvent water mol­ecules within the asymmetric unit. The water mol­ecules form a hydrogen-bonded network, displaying C—H⋯O, C—H⋯Br, O—H⋯Br, O—H⋯O and O—H⋯F inter­actions into layers parallel to (111). In each unit, the fluoro­phenyl rings of one ligand are stacked with the central ring of the other ligand via π–π inter­actions, with the closest centroid-to-plane distances being 3.445 (5), 3.636 (5), 3.397 (5) and 3.396 (5) Å. PMID:26870437

  5. Exposure assessment for methyl and total mercury from seafood consumption in Korea, 2005 to 2008.

    PubMed

    Moon, Hyo-Bang; Kim, Sang-Jo; Park, Hyejin; Jung, Yun Sun; Lee, Suuggyu; Kim, Yun-Hee; Choi, Minkyu

    2011-09-01

    Reports on the occurrence and intake assessment of mercury for Korean seafood are currently not available. This is the first report to estimate the intake of methyl (Me-Hg) and total mercury (T-Hg) from seafood consumption in Korea. The concentrations of Me-Hg and T-Hg in seafood ranged from 1.02 to 780 (mean: 55.6) ng g(-1) wet weight and 4.89 to 1008 (mean: 100) ng g(-1) wet weight, respectively. The residue levels of Me-Hg and T-Hg in Korean seafood were moderate compared with those found in other countries. The methylation ratios of fish, cephalopods and crustaceans were similar, but shellfish had lower values compared with other species. The intakes of Me-Hg and T-Hg from seafood consumption for the general population were estimated to be 38.8 and 73.8 ng kg(-1) body weight per day, respectively. Mackerel, tuna and squid made the highest contributions to the total intake of these contaminants. Among eight age groups, 30-49 year and 3-6 year age groups had the highest exposure to Me-Hg and T-Hg. The concentrations and intakes of Me-Hg and T-Hg from Korean seafood were less than the allowable residue levels and threshold intake levels suggested by Korean and international authorities. The present study may be useful for risk management of mercury in Korean seafood. PMID:21847486

  6. Inhibition of excision-repair of ultraviolet damage in human cells by exposure to methyl methanesulfonate.

    PubMed

    Park, S D; Choi, K H; Hong, S W; Cleaver, J E

    1981-07-01

    Unscheduled DNA synthesis and excision of pyrimidine dimers in human cells exposed to ultraviolet let were inhibited by exposure to methyl methanesulfonate (MMS, 1-2 mM), but repair of MMS damage was not inhibited by UV light. Because the pathways for excision of pyrimidine dimers and alkylation damage have previously been shown to be different, this observation implies a direct effect of alkylation on repair enzymes. We estimate that if inhibition is due to protein alkylation, the UV repair system must present an extremely large target to alkylation and may involve a complex of protein subunits in the order of 1 million daltons such that 1 or more alkylations occur per complex at the concentrations used. These results also indicate that the method of exposing cells to 2 DNA-damaging agents to determine whether they are repaired by common or different pathways can be quite unreliable because of other effects on the repair systems themselves. PMID:7196494

  7. Changes in Neuronal Dopamine Homeostasis following 1-Methyl-4-phenylpyridinium (MPP+) Exposure*

    PubMed Central

    Choi, Se Joon; Panhelainen, Anne; Schmitz, Yvonne; Larsen, Kristin E.; Kanter, Ellen; Wu, Min; Sulzer, David; Mosharov, Eugene V.

    2015-01-01

    1-Methyl-4-phenylpyridinium (MPP+), the active metabolite of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, selectively kills dopaminergic neurons in vivo and in vitro via a variety of toxic mechanisms, including mitochondrial dysfunction, generation of peroxynitrite, induction of apoptosis, and oxidative stress due to disruption of vesicular dopamine (DA) storage. To investigate the effects of acute MPP+ exposure on neuronal DA homeostasis, we measured stimulation-dependent DA release and non-exocytotic DA efflux from mouse striatal slices and extracellular, intracellular, and cytosolic DA (DAcyt) levels in cultured mouse ventral midbrain neurons. In acute striatal slices, MPP+ exposure gradually decreased stimulation-dependent DA release, followed by massive DA efflux that was dependent on MPP+ concentration, temperature, and DA uptake transporter activity. Similarly, in mouse midbrain neuronal cultures, MPP+ depleted vesicular DA storage accompanied by an elevation of cytosolic and extracellular DA levels. In neuronal cell bodies, increased DAcyt was not due to transmitter leakage from synaptic vesicles but rather to competitive MPP+-dependent inhibition of monoamine oxidase activity. Accordingly, monoamine oxidase blockers pargyline and l-deprenyl had no effect on DAcyt levels in MPP+-treated cells and produced only a moderate effect on the survival of dopaminergic neurons treated with the toxin. In contrast, depletion of intracellular DA by blocking neurotransmitter synthesis resulted in ∼30% reduction of MPP+-mediated toxicity, whereas overexpression of VMAT2 completely rescued dopaminergic neurons. These results demonstrate the utility of comprehensive analysis of DA metabolism using various electrochemical methods and reveal the complexity of the effects of MPP+ on neuronal DA homeostasis and neurotoxicity. PMID:25596531

  8. Aberrant 5’-CpG Methylation of Cord Blood TNFα Associated with Maternal Exposure to Polybrominated Diphenyl Ethers

    PubMed Central

    Wang, Xiaobin; Tang, Wan-Yee

    2015-01-01

    Growing evidence suggests that maternal exposures to endocrine disrupting chemicals during pregnancy may lead to poor pregnancy outcomes and increased fetal susceptibility to adult diseases. Polybrominated diphenyl ethers (PBDEs), which are ubiquitously used flame-retardants, could leach into the environment; and become persistent organic pollutants via bioaccumulation. In the United States, blood PBDE levels in adults range from 30–100 ng/g- lipid but the alarming health concern revolves around children who have reported blood PBDE levels 3 to 9-fold higher than adults. PBDEs disrupt endocrine, immune, reproductive and nervous systems. However, the mechanism underlying its adverse health effect is not fully understood. Epigenetics is a possible biological mechanism underlying maternal exposure-child health outcomes by regulating gene expression without changes in the DNA sequence. We sought to examine the relationship between maternal exposure to environmental PBDEs and promoter methylation of a proinflammatory gene, tumor necrosis factor alpha (TNFα). We measured the maternal blood PBDE levels and cord blood TNFα promoter methylation levels on 46 paired samples of maternal and cord blood from the Boston Birth Cohort (BBC). We showed that decreased cord blood TNFα methylation associated with high maternal PBDE47 exposure. CpG site-specific methylation showed significantly hypomethylation in the girl whose mother has a high blood PBDE47 level. Consistently, decreased TNFα methylation associated with an increase in TNFα protein level in cord blood. In conclusion, our finding provided evidence that in utero exposure to PBDEs may epigenetically reprogram the offspring’s immunological response through promoter methylation of a proinflammatory gene. PMID:26406892

  9. Aberrant 5'-CpG Methylation of Cord Blood TNFα Associated with Maternal Exposure to Polybrominated Diphenyl Ethers.

    PubMed

    Dao, Tyna; Hong, Xiumei; Wang, Xiaobin; Tang, Wan-Yee

    2015-01-01

    Growing evidence suggests that maternal exposures to endocrine disrupting chemicals during pregnancy may lead to poor pregnancy outcomes and increased fetal susceptibility to adult diseases. Polybrominated diphenyl ethers (PBDEs), which are ubiquitously used flame-retardants, could leach into the environment; and become persistent organic pollutants via bioaccumulation. In the United States, blood PBDE levels in adults range from 30-100 ng/g- lipid but the alarming health concern revolves around children who have reported blood PBDE levels 3 to 9-fold higher than adults. PBDEs disrupt endocrine, immune, reproductive and nervous systems. However, the mechanism underlying its adverse health effect is not fully understood. Epigenetics is a possible biological mechanism underlying maternal exposure-child health outcomes by regulating gene expression without changes in the DNA sequence. We sought to examine the relationship between maternal exposure to environmental PBDEs and promoter methylation of a proinflammatory gene, tumor necrosis factor alpha (TNFα). We measured the maternal blood PBDE levels and cord blood TNFα promoter methylation levels on 46 paired samples of maternal and cord blood from the Boston Birth Cohort (BBC). We showed that decreased cord blood TNFα methylation associated with high maternal PBDE47 exposure. CpG site-specific methylation showed significantly hypomethylation in the girl whose mother has a high blood PBDE47 level. Consistently, decreased TNFα methylation associated with an increase in TNFα protein level in cord blood. In conclusion, our finding provided evidence that in utero exposure to PBDEs may epigenetically reprogram the offspring's immunological response through promoter methylation of a proinflammatory gene. PMID:26406892

  10. Exposure to methyl tert-butyl ether and benzene among service station attendants and operators.

    PubMed Central

    Hartle, R

    1993-01-01

    Concerns for atmospheric pollution from auto exhaust have led to the blending of "oxygenates" with motor fuels. The most common oxygenate, methyl tert-butyl ether (MTBE) is currently required within several metropolitan areas (Denver and Phoenix) in the range of 12% of the motor fuel. Amendments to the Clean Air Act may expand this requirement to as many as 44 other areas of the United States in the near future. In consideration of the magnitude of potential uncontrolled exposures from its extensive use and a related concern involving the potential influence of MTBE blending on exposures to other constituents of gasoline (particularly benzene), an evaluation of exposures among service station attendants and operators was undertaken at the request, and in cooperation with, the American Petroleum Institute during the latter part of 1990. For application of the survey results to a broad audience, three categories or types of service stations were identified with regard to MTBE use and exposure potential: a) service stations that do not use MTBE or use it only as an octane enhancer, b) service stations with seasonal requirements to use 12-15% MTBE (the Denver, Colorado, and Phoenix, Arizona, metropolitan areas), and c) service stations equipped with stage II (active) vapor recovery systems (several coastal areas, most notably Southern California). At the two sampled service stations that use only minimal amounts of MTBE (less than 1%), only 1 of 32 personal breathing zone (PBZ) samples from attendants was above the analytical limit of detection, reported at 0.16 ppm. The geometric mean concentration of benzene among this same population (n = 32) was 0.04 ppm.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8020445

  11. Exposure to methyl tert-butyl ether and benzene among service station attendants and operators.

    PubMed

    Hartle, R

    1993-12-01

    Concerns for atmospheric pollution from auto exhaust have led to the blending of "oxygenates" with motor fuels. The most common oxygenate, methyl tert-butyl ether (MTBE) is currently required within several metropolitan areas (Denver and Phoenix) in the range of 12% of the motor fuel. Amendments to the Clean Air Act may expand this requirement to as many as 44 other areas of the United States in the near future. In consideration of the magnitude of potential uncontrolled exposures from its extensive use and a related concern involving the potential influence of MTBE blending on exposures to other constituents of gasoline (particularly benzene), an evaluation of exposures among service station attendants and operators was undertaken at the request, and in cooperation with, the American Petroleum Institute during the latter part of 1990. For application of the survey results to a broad audience, three categories or types of service stations were identified with regard to MTBE use and exposure potential: a) service stations that do not use MTBE or use it only as an octane enhancer, b) service stations with seasonal requirements to use 12-15% MTBE (the Denver, Colorado, and Phoenix, Arizona, metropolitan areas), and c) service stations equipped with stage II (active) vapor recovery systems (several coastal areas, most notably Southern California). At the two sampled service stations that use only minimal amounts of MTBE (less than 1%), only 1 of 32 personal breathing zone (PBZ) samples from attendants was above the analytical limit of detection, reported at 0.16 ppm. The geometric mean concentration of benzene among this same population (n = 32) was 0.04 ppm.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8020445

  12. Effects on specific promoter DNA methylation in zebrafish embryos and larvae following benzo[a]pyrene exposure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Benzo[a]pyrene (BaP) is an established reproductive and developmental toxicant. BaP exposure in humans and animals has been linked to infertility and multigenerational health consequences. DNA methylation is the most studied epigenetic mechanism that regulates gene expression, and mapping of methyla...

  13. Effects of methyl testosterone exposure on sexual differentiation in medaka, Oryzias latipes

    USGS Publications Warehouse

    Papoulias, D.M.; Noltie, D.B.; Tillitt, D.E.

    2000-01-01

    Studies were conducted to characterize effects of a known androgen on sexual differentiation and development of medaka, Oryzias latipes (d-rR strain), at two life stages. Embryos were injected with graded doses of methyl testosterone (MT) prior to epiboly. The occurrence of sex-reversal, and the gonadosomatic index (GSI) were evaluated in adults. Primary germ cells were counted and gonad volumes calculated for larvae to determine if sex-reversal could be detected at an early life stage. Sex-reversal of genetic females to phenotypic males was observed at both life stages. The GSI for phenotypic females was greater than for phenotypic males, while the GSI in XX males was similar to XY males. MT appeared to reduce the GSI of XX females exposed to MT but not sex-reversed. Our results indicate that embryonic exposure to androgens influences sexual development in medaka. Utilizing the d-rR strain of medaka allows detection of an effect as early as 2 weeks after chemical exposure making this a useful tool to screen chemicals for effects on sexual differentiation. Copyright (C) 2000.

  14. Prenatal alcohol exposure alters methyl metabolism and programs serotonin transporter and glucocorticoid receptor expression in brain

    PubMed Central

    Ngai, Ying Fai; Sulistyoningrum, Dian C.; O'Neill, Ryan; Innis, Sheila M.; Weinberg, Joanne

    2015-01-01

    Prenatal alcohol exposure (PAE) programs the fetal hypothalamic-pituitary-adrenal (HPA) axis, resulting in HPA dysregulation and hyperresponsiveness to stressors in adulthood. Molecular mechanisms mediating these alterations are not fully understood. Disturbances in one-carbon metabolism, a source of methyl donors for epigenetic processes, contributes to alcoholic liver disease. We assessed whether PAE affects one-carbon metabolism (including Mtr, Mat2a, Mthfr, and Cbs mRNA) and programming of HPA function genes (Nr3c1, Nr3c2, and Slc6a4) in offspring from ethanol-fed (E), pair-fed (PF), and ad libitum-fed control (C) dams. At gestation day 21, plasma total homocysteine and methionine concentrations were higher in E compared with C dams, and E fetuses had higher plasma methionine concentrations and lower whole brain Mtr and Mat2a mRNA compared with C fetuses. In adulthood (55 days), hippocampal Mtr and Cbs mRNA was lower in E compared with C males, whereas Mtr, Mat2a, Mthfr, and Cbs mRNA were higher in E compared with C females. We found lower Nr3c1 mRNA and lower nerve growth factor inducible protein A (NGFI-A) protein in the hippocampus of E compared with PF females, whereas hippocampal Slc6a4 mRNA was higher in E than C males. By contrast, hypothalamic Slc6a4 mRNA was lower in E males and females compared with C offspring. This was accompanied by higher hypothalamic Slc6a4 mean promoter methylation in E compared with PF females. These findings demonstrate that PAE is associated with alterations in one-carbon metabolism and has long-term and region-specific effects on gene expression in the brain. These findings advance our understanding of mechanisms of HPA dysregulation associated with PAE. PMID:26180184

  15. Embryonic caffeine exposure acts via A1 adenosine receptors to alter adult cardiac function and DNA methylation in mice.

    PubMed

    Buscariollo, Daniela L; Fang, Xiefan; Greenwood, Victoria; Xue, Huiling; Rivkees, Scott A; Wendler, Christopher C

    2014-01-01

    Evidence indicates that disruption of normal prenatal development influences an individual's risk of developing obesity and cardiovascular disease as an adult. Thus, understanding how in utero exposure to chemical agents leads to increased susceptibility to adult diseases is a critical health related issue. Our aim was to determine whether adenosine A1 receptors (A1ARs) mediate the long-term effects of in utero caffeine exposure on cardiac function and whether these long-term effects are the result of changes in DNA methylation patterns in adult hearts. Pregnant A1AR knockout mice were treated with caffeine (20 mg/kg) or vehicle (0.09% NaCl) i.p. at embryonic day 8.5. This caffeine treatment results in serum levels equivalent to the consumption of 2-4 cups of coffee in humans. After dams gave birth, offspring were examined at 8-10 weeks of age. A1AR+/+ offspring treated in utero with caffeine were 10% heavier than vehicle controls. Using echocardiography, we observed altered cardiac function and morphology in adult mice exposed to caffeine in utero. Caffeine treatment decreased cardiac output by 11% and increased left ventricular wall thickness by 29% during diastole. Using DNA methylation arrays, we identified altered DNA methylation patterns in A1AR+/+ caffeine treated hearts, including 7719 differentially methylated regions (DMRs) within the genome and an overall decrease in DNA methylation of 26%. Analysis of genes associated with DMRs revealed that many are associated with cardiac hypertrophy. These data demonstrate that A1ARs mediate in utero caffeine effects on cardiac function and growth and that caffeine exposure leads to changes in DNA methylation.

  16. Oxidative stress, telomere shortening, and DNA methylation in relation to low-to-moderate occupational exposure to welding fumes.

    PubMed

    Li, Huiqi; Hedmer, Maria; Wojdacz, Tomasz; Hossain, Mohammad Bakhtiar; Lindh, Christian H; Tinnerberg, Håkan; Albin, Maria; Broberg, Karin

    2015-10-01

    Evidence suggests that exposure to welding fumes is a risk factor for lung cancer. We examined relationships between low-to-moderate occupational exposure to particles from welding fumes and cancer-related biomarkers for oxidative stress, changes in telomere length, and alterations in DNA methylation. We enrolled 101 welders and 127 controls (all currently nonsmoking men) from southern Sweden. We performed personal sampling of respirable dust and measured 8-oxodG concentrations in urine using a simplified liquid chromatography tandem mass spectrometry method. Telomere length in peripheral blood was measured by quantitative polymerase chain reaction. Methylation status of 10 tumor suppressor genes was determined by methylation-sensitive high-resolution melting analysis. All analyses were adjusted for age, body mass index, previous smoking, passive smoking, current residence, and wood burning stove/boiler at home. Welders were exposed to respirable dust at 1.2 mg/m(3) (standard deviation, 3.3 mg/m(3); range, 0.1-19.3), whereas control exposures did not exceed 0.1 mg/m(3) (P < 0.001). Welders and controls did not differ in 8-oxodG levels (β = 1.2, P = 0.17) or relative telomere length (β = -0.053, P = 0.083) in adjusted models. Welders showed higher probability of adenomatous polyposis coli (APC) methylation in the unadjusted model (odds ratio = 14, P = 0.014), but this was not significant in the fully adjusted model (P = 0.052). Every working year as a welder was associated with 0.0066 units shorter telomeres (95% confidence interval -0.013 to -0.00053, P = 0.033). Although there were no clear associations between concentrations of respirable dust and the biomarkers, there were modest signs of associations between oxidative stress, telomere alterations, DNA methylation, and occupational exposure to low-to-moderate levels of particles. PMID:26013103

  17. Oxidative stress, telomere shortening, and DNA methylation in relation to low-to-moderate occupational exposure to welding fumes.

    PubMed

    Li, Huiqi; Hedmer, Maria; Wojdacz, Tomasz; Hossain, Mohammad Bakhtiar; Lindh, Christian H; Tinnerberg, Håkan; Albin, Maria; Broberg, Karin

    2015-10-01

    Evidence suggests that exposure to welding fumes is a risk factor for lung cancer. We examined relationships between low-to-moderate occupational exposure to particles from welding fumes and cancer-related biomarkers for oxidative stress, changes in telomere length, and alterations in DNA methylation. We enrolled 101 welders and 127 controls (all currently nonsmoking men) from southern Sweden. We performed personal sampling of respirable dust and measured 8-oxodG concentrations in urine using a simplified liquid chromatography tandem mass spectrometry method. Telomere length in peripheral blood was measured by quantitative polymerase chain reaction. Methylation status of 10 tumor suppressor genes was determined by methylation-sensitive high-resolution melting analysis. All analyses were adjusted for age, body mass index, previous smoking, passive smoking, current residence, and wood burning stove/boiler at home. Welders were exposed to respirable dust at 1.2 mg/m(3) (standard deviation, 3.3 mg/m(3); range, 0.1-19.3), whereas control exposures did not exceed 0.1 mg/m(3) (P < 0.001). Welders and controls did not differ in 8-oxodG levels (β = 1.2, P = 0.17) or relative telomere length (β = -0.053, P = 0.083) in adjusted models. Welders showed higher probability of adenomatous polyposis coli (APC) methylation in the unadjusted model (odds ratio = 14, P = 0.014), but this was not significant in the fully adjusted model (P = 0.052). Every working year as a welder was associated with 0.0066 units shorter telomeres (95% confidence interval -0.013 to -0.00053, P = 0.033). Although there were no clear associations between concentrations of respirable dust and the biomarkers, there were modest signs of associations between oxidative stress, telomere alterations, DNA methylation, and occupational exposure to low-to-moderate levels of particles.

  18. LINE-1 methylation in granulocyte DNA and trihalomethane exposure is associated with bladder cancer risk

    PubMed Central

    Salas, Lucas A; Villanueva, Cristina M; Tajuddin, Salman M; Amaral, André F S; Fernandez, Agustín F; Moore, Lee E; Carrato, Alfredo; Tardón, Adonina; Serra, Consol; García-Closas, Reina; Basagaña, Xavier; Rothman, Nathaniel; Silverman, Debra T; Cantor, Kenneth P; Kogevinas, Manolis; Real, Francisco X; Fraga, Mario F; Malats, Núria

    2014-01-01

    DNA methylation changes contribute to bladder carcinogenesis. Trihalomethanes (THM), a class of disinfection by-products, are associated with increased urothelial bladder cancer (UBC) risk. THM exposure in animal models produces DNA hypomethylation. We evaluated the relationship of LINE-1 5-methylcytosine levels (LINE-1%5mC) as outcome of long-term THM exposure among controls and as an effect modifier in the association between THM exposure and UBC risk. We used a case-control study of UBC conducted in Spain. We obtained personal lifetime residential THM levels and measured LINE-1%5mC by pyrosequencing in granulocyte DNA from blood samples in 548 incident cases and 559 hospital controls. Two LINE-1%5mC clusters (above and below 64%) were identified through unsupervised hierarchical cluster analysis. The association between THM levels and LINE-1%5mC was evaluated with β regression analyses and logistic regression was used to estimate odds ratios (OR) adjusting for covariables. LINE-1%5mC change between percentiles 75th and 25th of THM levels was 1.8% (95% confidence interval (CI): 0.1, 3.4%) among controls. THM levels above vs. below the median (26 μg/L) were associated with increased UBC risk, OR = 1.86 (95% CI: 1.25, 2.75), overall and among subjects with low levels of LINE-1%5mC (n = 975), OR = 2.14 (95% CI: 1.39, 3.30), but not associated with UBC risk among subjects’ high levels of LINE-1%5mC (n = 162), interaction P = 0.03. Results suggest a positive association between LINE-1%5mC and THM levels among controls, and LINE-1%5mC status may modify the association between UBC risk and THM exposure. Because reverse causation and chance cannot be ruled out, confirmation studies are warranted. PMID:25482586

  19. LINE-1 methylation in granulocyte DNA and trihalomethane exposure is associated with bladder cancer risk.

    PubMed

    Salas, Lucas A; Villanueva, Cristina M; Tajuddin, Salman M; Amaral, André F S; Fernandez, Agustín F; Moore, Lee E; Carrato, Alfredo; Tardón, Adonina; Serra, Consol; García-Closas, Reina; Basagaña, Xavier; Rothman, Nathaniel; Silverman, Debra T; Cantor, Kenneth P; Kogevinas, Manolis; Real, Francisco X; Fraga, Mario F; Malats, Núria

    2014-11-01

    DNA methylation changes contribute to bladder carcinogenesis. Trihalomethanes (THM), a class of disinfection by-products, are associated with increased urothelial bladder cancer (UBC) risk. THM exposure in animal models produces DNA hypomethylation. We evaluated the relationship of LINE-1 5-methylcytosine levels (LINE-1%5mC) as outcome of long-term THM exposure among controls and as an effect modifier in the association between THM exposure and UBC risk. We used a case-control study of UBC conducted in Spain. We obtained personal lifetime residential THM levels and measured LINE-1%5mC by pyrosequencing in granulocyte DNA from blood samples in 548 incident cases and 559 hospital controls. Two LINE-1%5mC clusters (above and below 64%) were identified through unsupervised hierarchical cluster analysis. The association between THM levels and LINE-1%5mC was evaluated with β regression analyses and logistic regression was used to estimate odds ratios (OR) adjusting for covariables. LINE-1%5mC change between percentiles 75(th) and 25(th) of THM levels was 1.8% (95% confidence interval (CI): 0.1, 3.4%) among controls. THM levels above vs. below the median (26 μg/L) were associated with increased UBC risk, OR = 1.86 (95% CI: 1.25, 2.75), overall and among subjects with low levels of LINE-1%5mC (n = 975), OR = 2.14 (95% CI: 1.39, 3.30), but not associated with UBC risk among subjects' high levels of LINE-1%5mC (n = 162), interaction P = 0.03. Results suggest a positive association between LINE-1%5mC and THM levels among controls, and LINE-1%5mC status may modify the association between UBC risk and THM exposure. Because reverse causation and chance cannot be ruled out, confirmation studies are warranted.

  20. Long-term neurobehavioral health effects of methyl parathion exposure in children in Mississippi and Ohio.

    PubMed

    Ruckart, Perri Zeitz; Kakolewski, Kirsten; Bove, Frank J; Kaye, Wendy E

    2004-01-01

    Methyl parathion (MP), an organophosphate pesticide licensed only for agricultural uses, was sprayed illegally for pest control in Mississippi and Ohio residences. To evaluate the association between MP exposure and neurobehavioral development, we assessed children 6 years or younger at the time of the spraying and local comparison groups of unexposed children using the Pediatric Environmental Neurobehavioral Test Battery (PENTB). The PENTB is composed of informant-based procedures (parent interview and questionnaires) and performance-based procedures (neurobehavioral tests for children 4 years or older) that evaluate cognitive, motor, sensory, and affect domains essential to neurobehavioral assessment. Children were classified as exposed or unexposed on the basis of urinary para-nitrophenol levels and environmental wipe samples for MP. Exposed children had more difficulties with tasks involving short-term memory and attention. Additionally, parents of exposed children reported that their children had more behavioral and motor skill problems than did parents of unexposed children. However, these effects were not consistently seen at both sites. There were no differences between exposed and unexposed children in tests for general intelligence, the integration of visual and motor skills, and multistep processing. Our findings suggest that MP might be associated with subtle changes to short-term memory and attention and contribute to problems with motor skills and some behaviors, but the results of the study are not conclusive.

  1. Long-term neurobehavioral health effects of methyl parathion exposure in children in Mississippi and Ohio.

    PubMed Central

    Ruckart, Perri Zeitz; Kakolewski, Kirsten; Bove, Frank J; Kaye, Wendy E

    2004-01-01

    Methyl parathion (MP), an organophosphate pesticide licensed only for agricultural uses, was sprayed illegally for pest control in Mississippi and Ohio residences. To evaluate the association between MP exposure and neurobehavioral development, we assessed children 6 years or younger at the time of the spraying and local comparison groups of unexposed children using the Pediatric Environmental Neurobehavioral Test Battery (PENTB). The PENTB is composed of informant-based procedures (parent interview and questionnaires) and performance-based procedures (neurobehavioral tests for children 4 years or older) that evaluate cognitive, motor, sensory, and affect domains essential to neurobehavioral assessment. Children were classified as exposed or unexposed on the basis of urinary para-nitrophenol levels and environmental wipe samples for MP. Exposed children had more difficulties with tasks involving short-term memory and attention. Additionally, parents of exposed children reported that their children had more behavioral and motor skill problems than did parents of unexposed children. However, these effects were not consistently seen at both sites. There were no differences between exposed and unexposed children in tests for general intelligence, the integration of visual and motor skills, and multistep processing. Our findings suggest that MP might be associated with subtle changes to short-term memory and attention and contribute to problems with motor skills and some behaviors, but the results of the study are not conclusive. PMID:14698930

  2. Placental mitochondrial methylation and exposure to airborne particulate matter in the early life environment: An ENVIRONAGE birth cohort study

    PubMed Central

    Janssen, Bram G; Byun, Hyang-Min; Gyselaers, Wilfried; Lefebvre, Wouter; Baccarelli, Andrea A; Nawrot, Tim S

    2015-01-01

    Most research to date has focused on epigenetic modifications in the nuclear genome, with little attention devoted to mitochondrial DNA (mtDNA). Placental mtDNA content has been shown to respond to environmental exposures that induce oxidative stress, including airborne particulate matter (PM). Damaged or non-functioning mitochondria are specifically degraded through mitophagy, exemplified by lower mtDNA content, and could be primed by epigenetic modifications in the mtDNA. We studied placental mtDNA methylation in the context of the early life exposome. We investigated placental tissue from 381 mother-newborn pairs that were enrolled in the ENVIRONAGE birth cohort. We determined mtDNA methylation by bisulfite-pyrosequencing in 2 regions, i.e., the D-loop control region and 12S rRNA (MT-RNR1), and measured mtDNA content by qPCR. PM2.5 exposure was calculated for each participant's home address using a dispersion model. An interquartile range (IQR) increment in PM2.5 exposure over the entire pregnancy was positively associated with mtDNA methylation (MT-RNR1: +0.91%, P = 0.01 and D-loop: +0.21%, P = 0.05) and inversely associated with mtDNA content (relative change of −15.60%, P = 0.001) in placental tissue. mtDNA methylation was estimated to mediate 54% [P = 0.01 (MT-RNR1)] and 27% [P = 0.06 (D-loop)] of the inverse association between PM2.5 exposure and mtDNA content. This study provides new insight into the mechanisms of altered mitochondrial function in the early life environment. Epigenetic modifications in the mitochondrial genome, especially in the MT-RNR1 region, substantially mediate the association between PM2.5 exposure during gestation and placental mtDNA content, which could reflect signs of mitophagy and mitochondrial death. PMID:25996590

  3. Placental mitochondrial methylation and exposure to airborne particulate matter in the early life environment: An ENVIRONAGE birth cohort study.

    PubMed

    Janssen, Bram G; Byun, Hyang-Min; Gyselaers, Wilfried; Lefebvre, Wouter; Baccarelli, Andrea A; Nawrot, Tim S

    2015-01-01

    Most research to date has focused on epigenetic modifications in the nuclear genome, with little attention devoted to mitochondrial DNA (mtDNA). Placental mtDNA content has been shown to respond to environmental exposures that induce oxidative stress, including airborne particulate matter (PM). Damaged or non-functioning mitochondria are specifically degraded through mitophagy, exemplified by lower mtDNA content, and could be primed by epigenetic modifications in the mtDNA. We studied placental mtDNA methylation in the context of the early life exposome. We investigated placental tissue from 381 mother-newborn pairs that were enrolled in the ENVIRONAGE birth cohort. We determined mtDNA methylation by bisulfite-pyrosequencing in 2 regions, i.e., the D-loop control region and 12S rRNA (MT-RNR1), and measured mtDNA content by qPCR. PM2.5 exposure was calculated for each participant's home address using a dispersion model. An interquartile range (IQR) increment in PM2.5 exposure over the entire pregnancy was positively associated with mtDNA methylation (MT-RNR1: +0.91%, P = 0.01 and D-loop: +0.21%, P = 0.05) and inversely associated with mtDNA content (relative change of -15.60%, P = 0.001) in placental tissue. mtDNA methylation was estimated to mediate 54% [P = 0.01 (MT-RNR1)] and 27% [P = 0.06 (D-loop)] of the inverse association between PM2.5 exposure and mtDNA content. This study provides new insight into the mechanisms of altered mitochondrial function in the early life environment. Epigenetic modifications in the mitochondrial genome, especially in the MT-RNR1 region, substantially mediate the association between PM2.5 exposure during gestation and placental mtDNA content, which could reflect signs of mitophagy and mitochondrial death. PMID:25996590

  4. A panel study of occupational exposure to fine particulate matter and changes in DNA methylation over a single workday and years worked in boilermaker welders

    PubMed Central

    2013-01-01

    Background Exposure to pollutants including metals and particulate air pollution can alter DNA methylation. Yet little is known about intra-individual changes in DNA methylation over time in relationship to environmental exposures. Therefore, we evaluated the effects of acute- and chronic metal-rich PM2.5 exposures on DNA methylation. Methods Thirty-eight male boilermaker welders participated in a panel study for a total of 54 person days. Whole blood was collected prior to any welding activities (pre-shift) and immediately after the exposure period (post-shift). The percentage of methylated cytosines (%mC) in LINE-1, Alu, and inducible nitric oxide synthase gene (iNOS) were quantified using pyrosequencing. Personal PM2.5 (particulate matter with an aerodynamic diameter ≤ 2.5 μm) was measured over the work-shift. A questionnaire assessed job history and years worked as a boilermaker. Linear mixed models with repeated measures evaluated associations between DNA methylation, PM2.5 concentration (acute exposure), and years worked as a boilermaker (chronic exposure). Results PM2.5 exposure was associated with increased methylation in the promoter region of the iNOS gene (β = 0.25, SE: 0.11, p-value = 0.04). Additionally, the number of years worked as a boilermaker was associated with increased iNOS methylation (β = 0.03, SE: 0.01, p-value = 0.03). No associations were observed for Alu or LINE-1. Conclusions Acute and chronic exposure to PM2.5 generated from welding activities was associated with a modest change in DNA methylation of the iNOS gene. Future studies are needed to confirm this association and determine if the observed small increase in iNOS methylation are associated with changes in NO production or any adverse health effect. PMID:23758843

  5. Bisphenol A Exposure May Induce Hepatic Lipid Accumulation via Reprogramming the DNA Methylation Patterns of Genes Involved in Lipid Metabolism.

    PubMed

    Ke, Zhang-Hong; Pan, Jie-Xue; Jin, Lu-Yang; Xu, Hai-Yan; Yu, Tian-Tian; Ullah, Kamran; Rahman, Tanzil Ur; Ren, Jun; Cheng, Yi; Dong, Xin-Yan; Sheng, Jian-Zhong; Huang, He-Feng

    2016-01-01

    Accumulating evidence suggests a role of bisphenol A (BPA) in metabolic disorders. However, the underlying mechanism is still unclear. Using a mouse BPA exposure model, we investigated the effects of long-term BPA exposure on lipid metabolism and the underlying mechanisms. The male mice exposed to BPA (0.5 μg BPA /kg/day, a human relevant dose) for 10 months exhibited significant hepatic accumulation of triglycerides and cholesterol. The liver cells from the BPA-exposed mice showed significantly increased expression levels of the genes related to lipid synthesis. These liver cells showed decreased DNA methylation levels of Srebf1 and Srebf2, and increased expression levels of Srebf1 and Srebf2 that may upregulate the genes related to lipid synthesis. The expression levels of DNA methyltransferases were decreased in BPA-exposed mouse liver. Hepa1-6 cell line treated with BPA showed decreased expression levels of DNA methyltransferases and increased expression levels of genes involved in lipid synthesis. DNA methyltransferase knockdown in Hepa1-6 led to hypo-methylation and increased expression levels of genes involved in lipid synthesis. Our results suggest that long-term BPA exposure could induce hepatic lipid accumulation, which may be due to the epigenetic reprogramming of the genes involved in lipid metabolism, such as the alterations of DNA methylation patterns. PMID:27502578

  6. Bisphenol A Exposure May Induce Hepatic Lipid Accumulation via Reprogramming the DNA Methylation Patterns of Genes Involved in Lipid Metabolism

    NASA Astrophysics Data System (ADS)

    Ke, Zhang-Hong; Pan, Jie-Xue; Jin, Lu-Yang; Xu, Hai-Yan; Yu, Tian-Tian; Ullah, Kamran; Rahman, Tanzil Ur; Ren, Jun; Cheng, Yi; Dong, Xin-Yan; Sheng, Jian-Zhong; Huang, He-Feng

    2016-08-01

    Accumulating evidence suggests a role of bisphenol A (BPA) in metabolic disorders. However, the underlying mechanism is still unclear. Using a mouse BPA exposure model, we investigated the effects of long-term BPA exposure on lipid metabolism and the underlying mechanisms. The male mice exposed to BPA (0.5 μg BPA /kg/day, a human relevant dose) for 10 months exhibited significant hepatic accumulation of triglycerides and cholesterol. The liver cells from the BPA-exposed mice showed significantly increased expression levels of the genes related to lipid synthesis. These liver cells showed decreased DNA methylation levels of Srebf1 and Srebf2, and increased expression levels of Srebf1 and Srebf2 that may upregulate the genes related to lipid synthesis. The expression levels of DNA methyltransferases were decreased in BPA-exposed mouse liver. Hepa1-6 cell line treated with BPA showed decreased expression levels of DNA methyltransferases and increased expression levels of genes involved in lipid synthesis. DNA methyltransferase knockdown in Hepa1-6 led to hypo-methylation and increased expression levels of genes involved in lipid synthesis. Our results suggest that long-term BPA exposure could induce hepatic lipid accumulation, which may be due to the epigenetic reprogramming of the genes involved in lipid metabolism, such as the alterations of DNA methylation patterns.

  7. Bisphenol A Exposure May Induce Hepatic Lipid Accumulation via Reprogramming the DNA Methylation Patterns of Genes Involved in Lipid Metabolism

    PubMed Central

    Ke, Zhang-Hong; Pan, Jie-Xue; Jin, Lu-Yang; Xu, Hai-Yan; Yu, Tian-Tian; Ullah, Kamran; Rahman, Tanzil Ur; Ren, Jun; Cheng, Yi; Dong, Xin-Yan; Sheng, Jian-Zhong; Huang, He-Feng

    2016-01-01

    Accumulating evidence suggests a role of bisphenol A (BPA) in metabolic disorders. However, the underlying mechanism is still unclear. Using a mouse BPA exposure model, we investigated the effects of long-term BPA exposure on lipid metabolism and the underlying mechanisms. The male mice exposed to BPA (0.5 μg BPA /kg/day, a human relevant dose) for 10 months exhibited significant hepatic accumulation of triglycerides and cholesterol. The liver cells from the BPA-exposed mice showed significantly increased expression levels of the genes related to lipid synthesis. These liver cells showed decreased DNA methylation levels of Srebf1 and Srebf2, and increased expression levels of Srebf1 and Srebf2 that may upregulate the genes related to lipid synthesis. The expression levels of DNA methyltransferases were decreased in BPA-exposed mouse liver. Hepa1-6 cell line treated with BPA showed decreased expression levels of DNA methyltransferases and increased expression levels of genes involved in lipid synthesis. DNA methyltransferase knockdown in Hepa1-6 led to hypo-methylation and increased expression levels of genes involved in lipid synthesis. Our results suggest that long-term BPA exposure could induce hepatic lipid accumulation, which may be due to the epigenetic reprogramming of the genes involved in lipid metabolism, such as the alterations of DNA methylation patterns. PMID:27502578

  8. Hair analysis as a useful procedure for detection of vapour exposure to chemical warfare agents: simulation of sulphur mustard with methyl salicylate.

    PubMed

    Spiandore, Marie; Piram, Anne; Lacoste, Alexandre; Josse, Denis; Doumenq, Pierre

    2014-06-01

    Chemical warfare agents (CWA) are highly toxic compounds which have been produced to kill or hurt people during conflicts or terrorist attacks. Despite the fact that their use is strictly prohibited according to international convention, populations' exposure still recently occurred. Development of markers of exposure to CWA is necessary to distinguish exposed victims from unexposed ones. We present the first study of hair usage as passive sampler to assess contamination by chemicals in vapour form. This work presents more particularly the hair adsorption capacity for methyl salicylate used as a surrogate of the vesicant sulphur mustard. Chemical vapours toxicity through the respiratory route has historically been defined through Haber's law's concentration-time (Ct) product, and vapour exposure of hair to methyl salicylate was conducted with various times or doses of exposure in the range of incapacitating and lethal Ct products corresponding to sulphur mustard. Following exposure, extraction of methyl salicylate from hair was conducted by simple soaking in dichloromethane. Methyl salicylate could be detected on hair for vapour concentration corresponding to about one fifth of the sulphur mustard concentration that would kill 50% of exposed individuals (LCt50). The amount of methyl salicylate recovered from hair increased with time or dose of exposure. It showed a good correlation with the concentration-time product, suggesting that hair could be used like a passive sampler to assess vapour exposure to chemical compounds. It introduces great perspectives concerning the use of hair as a marker of exposure to CWA.

  9. Effects of Exposure to Methyl Parathion on Egg Hatchability and Eggshell Chemical Composition in Podocnemis expansa (Testudines, Podocnemididae).

    PubMed

    Valdes, Sady Alexis Chavauty; Vieira, Lucélia Gonçalves; Ferreira, Caio Henrique; dos Santos Mendonça, Juliana; Ribeiro, Priscilla Rosa Queiroz; de Abreu Fernandes, Evandro; Santos, André Luiz Quagliatto

    2015-04-01

    Eggshell evaluation may serve as an indicator of the effect of substances released in the environment, which may change eggshell shape, size, structure, and/or chemical composition. Additionally, exposure may interfere with hatching rates in contaminated eggs. The objective of this study was to better understand how exposure to the insecticide methyl parathion interferes with chemical changes in eggshells of Podocnemis expansa throughout their artificial incubation, as well as with egg hatchability. A total of 343 P. expansa eggs were collected in a natural reproduction area for the species. These eggs were transferred to and artificially incubated in the Wild Animal Teaching and Research Laboratory at Universidade Federal de Uberlândia. On the first day of artificial incubation, 0, 35, 350, and 3500 ppb of methyl parathion were incorporated to the substrate. Eggs were collected every three days for chemical analysis of eggshells. Hatchability was evaluated as the number of hatchlings in each treatment, for the eggs that were not used in the chemical analysis. Student's T-test was used for data on eggshell chemical composition, and the Binomial Test for Two Proportions was used in the hatchability analysis, at a 5% significance level. It was observed that the incorporation of methyl parathion to the substrate on the first day of artificial incubation of P. expansa eggs reduced the levels of total fat in the shells throughout their incubation, besides reducing egg hatchability.

  10. Investigation of bromide's spectra by high resolution UV-laser

    NASA Astrophysics Data System (ADS)

    Zhang, Jin; Ma, Jian-guo

    2011-12-01

    Experimental investigation has been carried out for dissociation/ionisation of methyl bromide using time of flight mass spectrometer, then, the mass signals were assigned to H+, CHm+ (m= 0-3), iBr+ (i = 79, 81), and the main processes of multi-photon ionization and dissociation of CH3Br were given.

  11. Methylation of the estrogen receptor CpG island in lung tumors is related to the specific type of carcinogen exposure

    SciTech Connect

    Issa, J.P.J.; Baylin, S.B.; Belinsky, S.A. |

    1996-08-15

    Promoter methylation has recently been shown to be an alternative to mutation in inactivating tumor suppressor genes in human neoplasia. Although specific carcinogen exposures have been associated with characteristic mutation patterns in genes, the factors that lead to promoter hypermethylation remain unknown. One gene target for inactivation through promoter methylation is the estrogen receptor (ER). The purpose of this investigation was to determine the methylation status of this gene in lung tumors from smokers and those who never smoked and in rodents exposed to specific environmental carcinogens. Promoter methylation at the ER locus was detected in 4 of 11 tumors from never-smokers (36.4%) and 7 of 35 tumors from smokers (20%, P < 0.001). Lung tumors induced by the tobacco-derived carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone also had a low incidence (16.7%) of ER methylation. In marked contrast, spontaneous and plutonium-induced tumors had a very high (81.8%) incidence of ER methylation. X-ray-induced tumors had an intermediate frequency of ER methylation (38.1%). The presence of ER methylation was associated with absent ER expression in rodent lung cancer cell lines. These results show for the first time that gene-specific promoter methylation can be modulated differentially depending on carcinogen exposure. 39 refs., 4 figs.

  12. Early life lead exposure causes gender-specific changes in the DNA methylation profile of DNA extracted from dried blood spots

    PubMed Central

    Sen, Arko; Heredia, Nicole; Senut, Marie-Claude; Hess, Matthew; Land, Susan; Qu, Wen; Hollacher, Kurt; Dereski, Mary O; Ruden, Douglas M

    2015-01-01

    Aims In this paper, we tested the hypothesis that early life lead (Pb) exposure associated DNA methylation (5mC) changes are dependent on the sex of the child and can serve as biomarkers for Pb exposure. Methods In this pilot study, we measured the 5mC profiles of DNA extracted from dried blood spots (DBS) in a cohort of 43 children (25 males and 18 females; ages from 3 months to 5 years) from Detroit. Result & Discussion We found that the effect of Pb-exposure on the 5-mC profiles can be separated into three subtypes: affected methylation loci which are conserved irrespective of the sex of the child (conserved); affected methylation loci unique to males (male-specific); and affected methylation loci unique to females (female-specific). PMID:26077427

  13. Gamma Irradiation Does Not Induce Detectable Changes in DNA Methylation Directly following Exposure of Human Cells

    PubMed Central

    Lahtz, Christoph; Bates, Steven E.; Jiang, Yong; Li, Arthur X.; Wu, Xiwei; Hahn, Maria A.; Pfeifer, Gerd P.

    2012-01-01

    Environmental chemicals and radiation have often been implicated in producing alterations of the epigenome thus potentially contributing to cancer and other diseases. Ionizing radiation, released during accidents at nuclear power plants or after atomic bomb explosions, is a potentially serious health threat for the exposed human population. This type of high-energy radiation causes DNA damage including single- and double-strand breaks and induces chromosomal rearrangements and mutations, but it is not known if ionizing radiation directly induces changes in the epigenome of irradiated cells. We treated normal human fibroblasts and normal human bronchial epithelial cells with different doses of γ-radiation emitted from a cesium 137 (137Cs) radiation source. After a seven-day recovery period, we analyzed global DNA methylation patterns in the irradiated and control cells using the methylated-CpG island recovery assay (MIRA) in combination with high-resolution microarrays. Bioinformatics analysis revealed only a small number of potential methylation changes with low fold-difference ratios in the irradiated cells. These minor methylation differences seen on the microarrays could not be verified by COBRA (combined bisulfite restriction analysis) or bisulfite sequencing of selected target loci. Our study shows that acute γ-radiation treatment of two types of human cells had no appreciable direct effect on DNA cytosine methylation patterns in exposed cells. PMID:23024770

  14. Exposure to aflatoxin B1 in utero is associated with DNA methylation in white blood cells of infants in The Gambia

    PubMed Central

    Hernandez-Vargas, Hector; Castelino, Jovita; Silver, Matt J; Dominguez-Salas, Paula; Cros, Marie-Pierre; Durand, Geoffroy; Calvez-Kelm, Florence Le; Prentice, Andrew M; Wild, Christopher P; Moore, Sophie E; Hennig, Branwen J; Herceg, Zdenko; Gong, Yun Yun; Routledge, Michael N

    2015-01-01

    Background: Exposure to environmental toxins during embryonic development may lead to epigenetic changes that influence disease risk in later life. Aflatoxin is a contaminant of staple foods in sub-Saharan Africa, is a known human liver carcinogen and has been associated with stunting in infants. Methods: We have measured aflatoxin exposure in 115 pregnant women in The Gambia and examined the DNA methylation status of white blood cells from their infants at 2–8 months old (mean 3.6 ± 0.9). Aflatoxin exposure in women was assessed using an ELISA method to measure aflatoxin albumin (AF-alb) adducts in plasma taken at 1–16 weeks of pregnancy. Genome-wide DNA methylation of infant white blood cells was measured using the Illumina Infinium HumanMethylation450beadchip. Results: AF-alb levels ranged from 3.9 to 458.4 pg/mg albumin. We found that aflatoxin exposure in the mothers was associated to DNA methylation in their infants for 71 CpG sites (false discovery rate < 0.05), with an average effect size of 1.7% change in methylation. Aflatoxin-associated differential methylation was observed in growth factor genes such as FGF12 and IGF1, and immune-related genes such as CCL28, TLR2 and TGFBI. Moreover, one aflatoxin-associated methylation region (corresponding to the miR-4520b locus) was identified. Conclusions: This study shows that maternal exposure to aflatoxin during the early stages of pregnancy is associated with differential DNA methylation patterns of infants, including in genes related to growth and immune function. This reinforces the need for interventions to reduce aflatoxin exposure, especially during critical periods of fetal and infant development. PMID:25855716

  15. Oxidative stress, telomere shortening, and DNA methylation in relation to low‐to‐moderate occupational exposure to welding fumes

    PubMed Central

    Li, Huiqi; Hedmer, Maria; Wojdacz, Tomasz; Hossain, Mohammad Bakhtiar; Lindh, Christian H.; Tinnerberg, Håkan; Albin, Maria

    2015-01-01

    Evidence suggests that exposure to welding fumes is a risk factor for lung cancer. We examined relationships between low‐to‐moderate occupational exposure to particles from welding fumes and cancer‐related biomarkers for oxidative stress, changes in telomere length, and alterations in DNA methylation. We enrolled 101 welders and 127 controls (all currently nonsmoking men) from southern Sweden. We performed personal sampling of respirable dust and measured 8‐oxodG concentrations in urine using a simplified liquid chromatography tandem mass spectrometry method. Telomere length in peripheral blood was measured by quantitative polymerase chain reaction. Methylation status of 10 tumor suppressor genes was determined by methylation‐sensitive high‐resolution melting analysis. All analyses were adjusted for age, body mass index, previous smoking, passive smoking, current residence, and wood burning stove/boiler at home. Welders were exposed to respirable dust at 1.2 mg/m3 (standard deviation, 3.3 mg/m3; range, 0.1–19.3), whereas control exposures did not exceed 0.1 mg/m3 (P < 0.001). Welders and controls did not differ in 8‐oxodG levels (β = 1.2, P = 0.17) or relative telomere length (β = −0.053, P = 0.083) in adjusted models. Welders showed higher probability of adenomatous polyposis coli (APC) methylation in the unadjusted model (odds ratio = 14, P = 0.014), but this was not significant in the fully adjusted model (P = 0.052). Every working year as a welder was associated with 0.0066 units shorter telomeres (95% confidence interval −0.013 to −0.00053, P = 0.033). Although there were no clear associations between concentrations of respirable dust and the biomarkers, there were modest signs of associations between oxidative stress, telomere alterations, DNA methylation, and occupational exposure to low‐to‐moderate levels of particles. Environ. Mol. Mutagen. 56:684–693, 2015. © 2015 The Authors

  16. Health Risk Assessment for Inhalation Exposure to Methyl Tertiary Butyl Ether at Petrol Stations in Southern China.

    PubMed

    Hu, Dalin; Yang, Jianping; Liu, Yungang; Zhang, Wenjuan; Peng, Xiaowu; Wei, Qinzhi; Yuan, Jianhui; Zhu, Zhiliang

    2016-02-01

    Methyl tertiary butyl ether (MTBE), a well known gasoline additive, is used in China nationwide to enhance the octane number of gasoline and reduce harmful exhaust emissions, yet little is known regarding the potential health risk associated with occupational exposure to MTBE in petrol stations. In this study, 97 petrol station attendants (PSAs) in southern China were recruited for an assessment of the health risk associated with inhalation exposure to MTBE. The personal exposure levels of MTBE were analyzed by Head Space Solid Phase Microextraction GC/MS, and the demographic characteristics of the PSAs were investigated. Cancer and non-cancer risks were calculated with the methods recommended by the United States Environmental Protection Agency. The results showed that the exposure levels of MTBE in operating workers were much higher than among support staff (p < 0.01) and both were lower than 50 ppm (an occupational threshold limit value). The calculated cancer risks (CRs) at the investigated petrol stations was 0.170 to 0.240 per 10⁶ for operating workers, and 0.026 to 0.049 per 10⁶ for support staff, which are below the typical target range for risk management of 1 × 10(-6) to 1 × 10(-4); The hazard quotients (HQs) for all subjects were <1. In conclusion, our study indicates that the MTBE exposure of PSAs in southern China is in a low range which does not seem to be a significant health risk. PMID:26861375

  17. Continuous exposure to the deterrents cis-jasmone and methyl jasmonate does not alter the behavioural responses of Frankliniella occidentalis

    PubMed Central

    Egger, Barbara; Spangl, Bernhard; Koschier, Elisabeth Helene

    2016-01-01

    Behavioural responses of Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), a generalist, cell sap-feeding insect species with piercing-sucking mouthparts, after continuous exposure to two deterrent secondary plant compounds are investigated. We compared in choice assays on bean leaf discs, the settling, feeding, and oviposition preferences of F. occidentalis females that had no experience with the two fatty acid derivatives methyl jasmonate and cis-jasmone before testing (naïve thrips) vs. females that had been exposed to the deterrent compounds before testing (experienced thrips). The thrips were exposed to the deterrents at low or high concentrations for varied time periods and subsequently tested on bean leaf discs treated with the respective deterrent at either a low or a high concentration. Frankliniella occidentalis females avoided settling on the deterrent-treated bean leaf discs for an observation period of 6 h, independent of their previous experience. Our results demonstrate that feeding and oviposition deterrence of the jasmonates to the thrips were not altered by continuous exposure of the thrips to the jasmonates. Habituation was not induced, neither by exposure to the low concentration of the deterrents nor by exposure to the high concentration. These results indicate that the risk of habituation to two volatile deterrent compounds after repeated exposure is not evident in F. occidentalis. This makes the two compounds potential candidates to be integrated in pest management strategies. PMID:26726263

  18. Health Risk Assessment for Inhalation Exposure to Methyl Tertiary Butyl Ether at Petrol Stations in Southern China.

    PubMed

    Hu, Dalin; Yang, Jianping; Liu, Yungang; Zhang, Wenjuan; Peng, Xiaowu; Wei, Qinzhi; Yuan, Jianhui; Zhu, Zhiliang

    2016-02-06

    Methyl tertiary butyl ether (MTBE), a well known gasoline additive, is used in China nationwide to enhance the octane number of gasoline and reduce harmful exhaust emissions, yet little is known regarding the potential health risk associated with occupational exposure to MTBE in petrol stations. In this study, 97 petrol station attendants (PSAs) in southern China were recruited for an assessment of the health risk associated with inhalation exposure to MTBE. The personal exposure levels of MTBE were analyzed by Head Space Solid Phase Microextraction GC/MS, and the demographic characteristics of the PSAs were investigated. Cancer and non-cancer risks were calculated with the methods recommended by the United States Environmental Protection Agency. The results showed that the exposure levels of MTBE in operating workers were much higher than among support staff (p < 0.01) and both were lower than 50 ppm (an occupational threshold limit value). The calculated cancer risks (CRs) at the investigated petrol stations was 0.170 to 0.240 per 10⁶ for operating workers, and 0.026 to 0.049 per 10⁶ for support staff, which are below the typical target range for risk management of 1 × 10(-6) to 1 × 10(-4); The hazard quotients (HQs) for all subjects were <1. In conclusion, our study indicates that the MTBE exposure of PSAs in southern China is in a low range which does not seem to be a significant health risk.

  19. Health Risk Assessment for Inhalation Exposure to Methyl Tertiary Butyl Ether at Petrol Stations in Southern China

    PubMed Central

    Hu, Dalin; Yang, Jianping; Liu, Yungang; Zhang, Wenjuan; Peng, Xiaowu; Wei, Qinzhi; Yuan, Jianhui; Zhu, Zhiliang

    2016-01-01

    Methyl tertiary butyl ether (MTBE), a well known gasoline additive, is used in China nationwide to enhance the octane number of gasoline and reduce harmful exhaust emissions, yet  little is known regarding the potential health risk associated with occupational exposure to MTBE in petrol stations. In this study, 97 petrol station attendants (PSAs) in southern China were recruited for an assessment of the health risk associated with inhalation exposure to MTBE. The personal exposure levels of MTBE were analyzed by Head Space Solid Phase Microextraction GC/MS, and the demographic characteristics of the PSAs were investigated. Cancer and non-cancer risks were calculated with the methods recommended by the United States Environmental Protection Agency. The results showed that the exposure levels of MTBE in operating workers were much higher than among support staff (p < 0.01) and both were lower than 50 ppm (an occupational threshold limit value). The calculated cancer risks (CRs) at the investigated petrol stations was 0.170 to 0.240 per 106 for operating workers, and 0.026 to 0.049 per 106 for support staff, which are below the typical target range for risk management of 1 × 10−6 to 1 × 10−4; The hazard quotients (HQs) for all subjects were <1. In conclusion, our study indicates that the MTBE exposure of PSAs in southern China is in a low range which does not seem to be a significant health risk. PMID:26861375

  20. INHALATION EXPOSURE TO METHYL TERT-BUTYL ETHER (MTBE) AND DIBROMOCHLOROMETHANE (DBCM) USING CONTINUOUS BREATH ANALYSIS

    EPA Science Inventory

    The oxygenate methyl tert-butyl ether (MTBE) has been added to gasoline to help meet national ambient air quality standards in those parts of the U.S. that are non-compliant for carbon monoxide. Although MTBE has provided important health benefits in terms of reduced haza...

  1. Epigenetic Vestiges of Early Developmental Adversity: Childhood Stress Exposure and DNA Methylation in Adolescence

    ERIC Educational Resources Information Center

    Essex, Marilyn J.; Boyce, W. Thomas; Hertzman, Clyde; Lam, Lucia L.; Armstrong, Jeffrey M.; Neumann, Sarah M. A.; Kobor, Michael S.

    2013-01-01

    Fifteen-year-old adolescents (N = 109) in a longitudinal study of child development were recruited to examine differences in DNA methylation in relation to parent reports of adversity during the adolescents' infancy and preschool periods. Microarray technology applied to 28,000 cytosine-guanine dinucleotide sites within DNA derived from buccal…

  2. PHYSIOLOGICALLY BASED PHARMACOKINETIC MODEL FOR HUMAN EXPOSURES TO METHYL TERTIARY-BUTYL ETHER

    EPA Science Inventory

    Humans can be exposed by inhalation, ingestion, or dermal absorption to methyl tertiary-butyl ether (MTBE), an oxygenated fuel additive, from contaminated water sources. The purpose of this research was to develop a physiologically based pharmacokinetic model describing in human...

  3. Select Prenatal Environmental Exposures and Subsequent Alterations of Gene-Specific and Repetitive Element DNA Methylation in Fetal Tissues.

    PubMed

    Green, Benjamin B; Marsit, Carmen J

    2015-06-01

    Strong evidence implicates maternal environmental exposures in contributing to adverse outcomes during pregnancy and later in life through the developmental origins of health and disease hypothesis. Recent research suggests these effects are mediated through the improper regulation of DNA methylation in offspring tissues, specifically placental tissue, which plays a critical role in fetal development. This article reviews the relevant literature relating DNA methylation in multiple tissues at or near delivery to several prenatal environmental toxicants and stressors, including cigarette smoke, endocrine disruptors, heavy metals, as well as maternal diet. These human studies expand upon previously reported outcomes in animal model interventions and include effects on both imprinted and non-imprinted genes. We have also noted some of the strengths and limitations in the approaches used, and consider the appropriate interpretation of these findings in terms of their effect size and their relationship to differential gene expression and potential health outcomes. The studies suggest an important role of DNA methylation in mediating the effects of the intrauterine environment on children's health and a need for additional research to better clarify the role of this epigenetic mechanism as well as others. PMID:26231362

  4. Select Prenatal Environmental Exposures and Subsequent Alterations of Gene-Specific and Repetitive Element DNA Methylation in Fetal Tissues

    PubMed Central

    Green, Benjamin B.; Marsit, Carmen J.

    2015-01-01

    Strong evidence implicates maternal environmental exposures in contributing to adverse outcomes during pregnancy and later in life through the developmental origins of health and disease hypothesis. Recent research suggests these effects are mediated through the improper regulation of DNA methylation in offspring tissues, specifically placental tissue, which plays a critical role in fetal development. This article reviews the relevant literature relating DNA methylation in multiple tissues at or near delivery to several prenatal environmental toxicants and stressors, including cigarette smoke, endocrine disruptors, heavy metals, as well as maternal diet. These human studies expand upon previously reported outcomes in animal model interventions and include effects on both imprinted and non-imprinted genes. We have also noted some of the strengths and limitations in the approaches used, and consider the appropriate interpretation of these findings in terms of their effect size and their relationship to differential gene expression and potential health outcomes. The studies suggest an important role of DNA methylation in mediating the effects of the intrauterine environment on children’s health and a need for additional research to better clarify the role of this epigenetic mechanism as well as others. PMID:26231362

  5. Rapacuronium bromide (Organon Teknika).

    PubMed

    Plowman, A N

    1999-07-01

    Organon Teknika's rapacuronium bromide (Org-9487), the 16-N-allyl, 17-beta-propionate analog of vecuronium bromide, is in phase III clinical trials in the US and Europe for potential use as an anesthetic. It is a steroidal neuromuscular blocking drug characterized by low potency, rapid rate of block development and short time course of neuromuscular blocking action as compared with other non-depolarizing compounds [170210,221422]. A multicenter, randomized, assessor-blind, placebo-controlled, dose-finding study in patients undergoing tracheal intubation showed that the drug produced a dose dependent neuromuscular block. Doses of 1.5 to 2 mg/kg allowed rapid intubation and short duration of action [273336]. Another study showed that the drug does not cause cardiovascular side-effects [273336]. A meeting was held in Europe on 8 February 1999 to brief company employees on the registration and release of rapacuronium [319211] for which the company anticipates a launch in late 1999 [320706]. Organon estimates that the market value of Org-9487 is between dollar 100 m and dollar 250 m a year, each for Europe and the US [221422].

  6. Liver DNA methylation analysis in adult female C57BL/6JxFVB mice following perinatal exposure to bisphenol A.

    PubMed

    van Esterik, J C J; Vitins, A P; Hodemaekers, H M; Kamstra, J H; Legler, J; Pennings, J L A; Steegenga, W T; Lute, C; Jelinek, J; Issa, J P J; Dollé, M E T; van der Ven, L T M

    2015-01-01

    Bisphenol A (BPA) is a compound released from plastics and other consumer products used in everyday life. BPA exposure early in fetal development is proposed to contribute to programming of chronic diseases like obesity and diabetes, by affecting DNA methylation levels. Previously, we showed that in utero and lactational exposure of C57BL/6JxFVB hybrid mice via maternal feed using a dose range of 0-3000μg/kg body weight/day resulted in a sex-dependent altered metabolic phenotype in offspring at 23 weeks of age. The most univocal effects were observed in females, with reduced body weights and related metabolic effects associated with perinatal BPA exposure. To identify whether the effects of BPA in females are associated with changes in DNA methylation, this was analyzed in liver, which is important in energy homeostasis. Measurement of global DNA methylation did not show any changes. Genome-wide DNA methylation analysis at specific CpG sites in control and 3000μg/kg body weight/day females with the digital restriction enzyme analysis of methylation (DREAM) assay revealed potential differences, that could, however, not be confirmed by bisulfite pyrosequencing. Overall, we demonstrated that the observed altered metabolic phenotype in female offspring after maternal exposure to BPA was not detectably associated with liver DNA methylation changes. Still, other tissues may be more informative.

  7. Lifelong exposure to bisphenol a alters cardiac structure/function, protein expression, and DNA methylation in adult mice.

    PubMed

    Patel, Bhavini B; Raad, Mohamad; Sebag, Igal A; Chalifour, Lorraine E

    2013-05-01

    Bisphenol A (BPA) is an estrogenizing endocrine disruptor compound of concern. Our objective was to test whether lifelong BPA would impact cardiac structure/function, calcium homeostasis protein expression, and the DNA methylation of cardiac genes. We delivered 0.5 and 5.0 µg/kg/day BPA lifelong from gestation day 11 or 200 µg/kg/day from gestation day 11 to postnatal day 21 via the drinking water to C57bl/6n mice. BPA 5.0 males and females had increased body weight, body mass index, body surface area, and adiposity. Echocardiography identified concentric remodeling in all BPA-treated males. Systolic and diastolic cardiac functions were essentially similar, but lifelong BPA enhanced male and reduced female sex-specific differences in velocity of circumferential shortening and ascending aorta velocity time integral. Diastolic blood pressure was increased in all BPA females. The calcium homeostasis proteins sarcoendoplasmic reticulum ATPase 2a (SERCA2a), sodium calcium exchanger-1, phospholamban (PLB), phospho-PLB, and calsequestrin 2 are important for contraction and relaxation. Changes in their expression suggest increased calcium mobility in males and reduced calcium mobility in females supporting the cardiac function changes. DNA methyltransferase 3a expression was increased in all BPA males and BPA 0.5 females and reduced in BPA 200 females. Global DNA methylation was increased in BPA 0.5 males and reduced in BPA 0.5 females. BPA induced sex-specific altered DNA methylation in specific CpG pairs in the calsequestrin 2 CpG island. These results suggest that continual exposure to BPA impacts cardiac structure/function, protein expression, and epigenetic DNA methylation marks in males and females.

  8. Gene-Specific Differential DNA Methylation and Chronic Arsenic Exposure in an Epigenome-Wide Association Study of Adults in Bangladesh

    PubMed Central

    Argos, Maria; Chen, Lin; Jasmine, Farzana; Tong, Lin; Pierce, Brandon L.; Roy, Shantanu; Paul-Brutus, Rachelle; Gamble, Mary V.; Harper, Kristin N.; Parvez, Faruque; Rahman, Mahfuzar; Rakibuz-Zaman, Muhammad; Slavkovich, Vesna; Baron, John A.; Graziano, Joseph H.; Kibriya, Muhammad G.

    2014-01-01

    Background: Inorganic arsenic is one of the most common naturally occurring contaminants found in the environment. Arsenic is associated with a number of health outcomes, with epigenetic modification suggested as a potential mechanism of toxicity. Objective: Among a sample of 400 adult participants, we evaluated the association between arsenic exposure, as measured by blood and urinary total arsenic concentrations, and epigenome-wide white blood cell DNA methylation. Methods: We used linear regression models to examine the associations between arsenic exposure and methylation at each CpG site, adjusted for sex, age, and batch. Differentially methylated loci were subsequently examined in relation to corresponding gene expression for functional evidence of gene regulation. Results: In adjusted analyses, we observed four differentially methylated CpG sites with urinary total arsenic concentration and three differentially methylated CpG sites with blood arsenic concentration, based on the Bonferroni-corrected significance threshold of p < 1 × 10–7. Methylation of PLA2G2C (probe cg04605617) was the most significantly associated locus in relation to both urinary (p = 3.40 × 10–11) and blood arsenic concentrations (p = 1.48 × 10–11). Three additional novel methylation loci—SQSTM1 (cg01225779), SLC4A4 (cg06121226), and IGH (cg13651690)—were also significantly associated with arsenic exposure. Further, there was evidence of methylation-related gene regulation based on gene expression for a subset of differentially methylated loci. Conclusions: We observed significant associations between arsenic exposure and gene-specific differential white blood cell DNA methylation, suggesting that epigenetic modifications may be an important pathway underlying arsenic toxicity. The specific differentially methylated loci identified may inform potential pathways for future interventions. Citation: Argos M, Chen L, Jasmine F, Tong L, Pierce BL, Roy S, Paul-Brutus R, Gamble MV

  9. Alveolar breath sampling and analysis to assess exposures to methyl tertiary butyl ether (MTBE) during motor vehicle refueling

    SciTech Connect

    Lindstrom, A.B.; Pleil, J.D.

    1996-07-01

    In this study we present a sampling and analytical methodology that can be used to assess consumers` exposures to methyl tertiary butyl ether (MTBE) that may result from routine vehicle refueling operations. The method is based on the collection of alveolar breath samples using evacuated one-liter stainless steel canisters and analysis using a gas chromatograph-mass spectrometer equipped with a patented `valveless` cryogenic preconcentrator. To demonstrate the utility of this approach, a series of breath samples was collected from two individuals (the person pumping the fuel and a nearby observer) immediately before and for 64 min after a vehicle was refueled with premium grade gasoline. Results demonstrate low levels of MTBE in both subjects` breaths before refueling, and levels that increased by a factor of 35 to 100 after the exposure. Breath elimination models fitted to the post exposure measurements indicate that the half-life of MTBE in the first physiological compartment was between 1.3 and 2.9 min. Analysis of the resulting models suggests that breath elimination of MTBE during the 64 min monitoring period was approximately 155 {mu}g for the refueling subject while it was only 30 {mu}g for the nearby observer. This analysis also shows that the post exposure breath elimination of other gasoline constituents was consistent with previously published observations. 20 refs., 3 figs., 4 tabs.

  10. Resistance in cholinesterase activity after an acute and subchronic exposure to azinphos-methyl in the freshwater gastropod Biomphalaria straminea.

    PubMed

    Bianco, Karina; Otero, Sofía; Oliver, Agustina Balazote; Nahabedian, Daniel; Kristoff, Gisela

    2014-11-01

    magnitude higher than cholinesterase. A greater efficiency (Vmax/Km) was obtained using acetylthiocholine and p-nitrophenyl butyrate. Acute exposure to azinphos-methyl did not cause inhibition of cholinesterase activity until 10 mg L(-1) used. Carboxylesterases towards p-nitrophenyl butyrate was inhibited by azinphos-methyl being the IC502.20±0.75 mg L(-1) of azinphos-methyl. Subchronic exposure to environmental concentrations of azinphos-methyl (0.02 and 0.2 mg L(-1)) produced a decrease in survival, protein content and carboxylesterases activity despite no inhibition of cholinesterase activity was observed. B. straminea cholinesterase is not a sensible biomarker. On the contrary, carboxylesterases activity was inhibited by azinphos-methyl. Carboxylesterases could be protecting cholinesterase activity and therefore, protecting the organism from neurotoxicity. This work confirms the advantages of measuring cholinesterases and carboxylesterases jointly in aquatic biomonitoring of pesticide contamination. This becomes relevant in order to find more sensitive biomarkers and new strategies to protect non-target aquatic organisms from pesticide contamination.

  11. Iron bromide vapor laser

    NASA Astrophysics Data System (ADS)

    Sukhanov, V. B.; Shiyanov, D. V.; Trigub, M. V.; Dimaki, V. A.; Evtushenko, G. S.

    2016-03-01

    We have studied the characteristics of a pulsed gas-discharge laser on iron bromide vapor generating radiation with a wavelength of 452.9 nm at a pulse repetition frequency (PRF) of 5-30 kHz. The maximum output power amounted to 10 mW at a PRF within 5-15 kHz for a voltage of 20-25 kV applied to electrodes of the discharge tube. Addition of HBr to the medium produced leveling of the radial profile of emission. Initial weak lasing at a wavelength of 868.9 nm was observed for the first time, which ceased with buildup of the main 452.9-nm line.

  12. Potassium bromide-associated panniculitis.

    PubMed

    Boynosky, N A; Stokking, L B

    2014-12-01

    Two cases of panniculitis associated with administration of potassium bromide in dogs are reported. Both dogs were treated with potassium bromide for idiopathic epilepsy for over 1 year. Dose increases in both cases were associated with panniculitis, characterised by painful subcutaneous nodules in a generalised distribution over the trunk. Nodule eruption waxed and waned in one dog and was persistent in the other. In both cases, panniculitis was accompanied by lethargy and pyrexia. Panniculitis, lethargy and pyrexia resolved and failed to recur after discontinuation of potassium bromide. No other cause of panniculitis could be determined for either dog. Panniculitis has been reported after administration of potassium bromide in humans and may be a form of drug-induced erythema nodosum. To the authors' knowledge, these are the first reports of potassium bromide-associated panniculitis in dogs.

  13. Effects of arsenic exposure on DNA methylation in cord blood samples from newborn babies and in a human lymphoblast cell line

    PubMed Central

    2012-01-01

    Background Accumulating evidence indicates that in utero exposure to arsenic is associated with congenital defects and long-term disease consequences including cancers. Recent studies suggest that arsenic carcinogenesis results from epigenetic changes, particularly in DNA methylation. This study aimed to investigate DNA methylation changes as a result of arsenic exposure in utero and in vitro. Methods For the exposure in utero study, a total of seventy-one newborns (fifty-five arsenic-exposed and sixteen unexposed newborns) were recruited. Arsenic concentrations in the drinking water were measured, and exposure in newborns was assessed by measurement of arsenic concentrations in cord blood, nails and hair by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In the in vitro study, human lymphoblasts were treated with arsenite at 0-100 μM for two, four and eight hours (short-term) and at 0, 0.5 and 1.0 μM for eight-weeks period (long-term). DNA methylation was analyzed in cord blood lymphocytes and lymphoblasts treated with arsenite in vitro. Global DNA methylation was determined as LINE-1 methylation using combined bisulfite restriction analysis (COBRA) and total 5-methyldeoxycytidine (5MedC) content which was determined by HPLC-MS/MS. Methylation of p53 was determined at the promoter region using methylation-specific restriction endonuclease digestion with MspI and HpaII. Results Results showed that arsenic-exposed newborns had significantly higher levels of arsenic in cord blood, fingernails, toenails and hair than those of the unexposed subjects and a slight increase in promoter methylation of p53 in cord blood lymphocytes which significantly correlated with arsenic accumulation in nails (p < 0.05) was observed, while LINE-1 methylation was unchanged. Short-term in vitro arsenite treatment in lymphoblastoid cells clearly demonstrated a significant global hypomethylation, determined as reduction in LINE-1 methylation and total 5-MedC content, and p53

  14. Epigenetic modulation upon exposure of lung fibroblasts to TiO2 and ZnO nanoparticles: alterations in DNA methylation

    PubMed Central

    Patil, Nayana A; Gade, WN; Deobagkar, Deepti D

    2016-01-01

    Titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles (NPs) are promising candidates for numerous applications in consumer products. This will lead to increased human exposure, thus posing a threat to human health. Both these types of NPs have been studied for their cell toxicity, immunotoxicity, and genotoxicity. However, effects of these NPs on epigenetic modulations have not been studied. Epigenetics is an important link in the genotype and phenotype modulation and misregulation can often lead to lifestyle diseases. In this study, we have evaluated the DNA methylation-based epigenetic changes upon exposure to various concentrations of NPs. The investigation was designed to evaluate global DNA methylation, estimating the corresponding methyltransferase activity and expression of Dnmt gene using lung fibroblast (MRC5) cell line as lungs are the primary route of entry and target of occupational exposure to TiO2 and ZnO NPs. Enzyme-linked immunosorbent assay-based immunochemical assay revealed dose-related decrease in global DNA methylation and DNA methyltransferase activity. We also found direct correlation between the concentration of NPs, global methylation levels, and expression levels of Dnmt1, 3A, and 3B genes upon exposure. This is the first study to investigate effect of exposure to TiO2 and ZnO on DNA methylation levels in MRC5 cells. Epigenetic processes are known to play an important role in reprogramming and adaptation ability of an organism and can have long-term consequences. We suggest that changes in DNA methylation can serve as good biomarkers for early exposure to NPs since they occur at concentrations well below the sublethal levels. Our results demonstrate a clear epigenetic alteration in response to metal oxide NPs and that this effect was dose-dependent.

  15. Epigenetic modulation upon exposure of lung fibroblasts to TiO2 and ZnO nanoparticles: alterations in DNA methylation

    PubMed Central

    Patil, Nayana A; Gade, WN; Deobagkar, Deepti D

    2016-01-01

    Titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles (NPs) are promising candidates for numerous applications in consumer products. This will lead to increased human exposure, thus posing a threat to human health. Both these types of NPs have been studied for their cell toxicity, immunotoxicity, and genotoxicity. However, effects of these NPs on epigenetic modulations have not been studied. Epigenetics is an important link in the genotype and phenotype modulation and misregulation can often lead to lifestyle diseases. In this study, we have evaluated the DNA methylation-based epigenetic changes upon exposure to various concentrations of NPs. The investigation was designed to evaluate global DNA methylation, estimating the corresponding methyltransferase activity and expression of Dnmt gene using lung fibroblast (MRC5) cell line as lungs are the primary route of entry and target of occupational exposure to TiO2 and ZnO NPs. Enzyme-linked immunosorbent assay-based immunochemical assay revealed dose-related decrease in global DNA methylation and DNA methyltransferase activity. We also found direct correlation between the concentration of NPs, global methylation levels, and expression levels of Dnmt1, 3A, and 3B genes upon exposure. This is the first study to investigate effect of exposure to TiO2 and ZnO on DNA methylation levels in MRC5 cells. Epigenetic processes are known to play an important role in reprogramming and adaptation ability of an organism and can have long-term consequences. We suggest that changes in DNA methylation can serve as good biomarkers for early exposure to NPs since they occur at concentrations well below the sublethal levels. Our results demonstrate a clear epigenetic alteration in response to metal oxide NPs and that this effect was dose-dependent. PMID:27660443

  16. Combined Inhaled Diesel Exhaust Particles and Allergen Exposure Alter Methylation of T Helper Genes and IgE Production In Vivo

    PubMed Central

    Liu, Jinming; Ballaney, Manisha; Al-alem, Umaima; Quan, Chunli; Jin, Ximei; Perera, Frederica; Chen, Lung-Chi; Miller, Rachel L.

    2008-01-01

    Changes in methylation of CpG sites at the interleukin (IL)-4 and interferon (IFN)-γ promoters are associated with T helper (Th) 2 polarization in vitro. No previous studies have examined whether air pollution or allergen exposure alters methylation of these two genes in vivo. We hypothesized that diesel exhaust particles (DEP) would induce hypermethylation of the IFN-γ promoter and hypomethylation of IL-4 in CD4+ T cells among mice sensitized to the fungus allergen Aspergillus fumigatus.We also hypothesized that DEP-induced methylation changes would affect immunoglobulin (Ig) E regulation. BALB/c mice were exposed to a 3-week course of inhaled DEP exposure while undergoing intranasal sensitization to A. fumigatus. Purified DNA from splenic CD4+ cells underwent bisulfite treatment, PCR amplification, and pyrosequencing. Sera IgE levels were compared with methylation levels at several CpG sites in the IL-4 and IFN-γ promoter. Total IgE production was increased following intranasal sensitization A. fumigatus. IgE production was augmented further following combined exposure to A. fumigatus and DEP exposure. Inhaled DEP exposure and intranasal A. fumigatus induced hypermethylation at CpG−45, CpG−53, CpG−205 sites of the IFN-γ promoter and hypomethylation at CpG−408 of the IL-4 promoter. Altered methylation of promoters of both genes was correlated significantly with changes in IgE levels. This study is the first to demonstrate that inhaled environmental exposures influence methylation of Th genes in vivo, supporting a new paradigm in asthma pathogenesis. PMID:18042818

  17. Assessment of global and gene-specific DNA methylation in rat liver and kidney in response to non-genotoxic carcinogen exposure.

    PubMed

    Ozden, Sibel; Turgut Kara, Neslihan; Sezerman, Osman Ugur; Durasi, İlknur Melis; Chen, Tao; Demirel, Goksun; Alpertunga, Buket; Chipman, J Kevin; Mally, Angela

    2015-12-01

    Altered expression of tumor suppressor genes and oncogenes, which is regulated in part at the level of DNA methylation, is an important event involved in non-genotoxic carcinogenesis. This may serve as a marker for early detection of non-genotoxic carcinogens. Therefore, we evaluated the effects of non-genotoxic hepatocarcinogens, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), hexachlorobenzene (HCB), methapyrilene (MPY) and male rat kidney carcinogens, d-limonene, p-dichlorobenzene (DCB), chloroform and ochratoxin A (OTA) on global and CpG island promoter methylation in their respective target tissues in rats. No significant dose-related effects on global DNA hypomethylation were observed in tissues of rats compared to vehicle controls using LC-MS/MS in response to short-term non-genotoxic carcinogen exposure. Initial experiments investigating gene-specific methylation using methylation-specific PCR and bisulfite sequencing, revealed partial methylation of p16 in the liver of rats treated with HCB and TCDD. However, no treatment related effects on the methylation status of Cx32, e-cadherin, VHL, c-myc, Igfbp2, and p15 were observed. We therefore applied genome-wide DNA methylation analysis using methylated DNA immunoprecipitation combined with microarrays to identify alterations in gene-specific methylation. Under the conditions of our study, some genes were differentially methylated in response to MPY and TCDD, whereas d-limonene, DCB and chloroform did not induce any methylation changes. 90-day OTA treatment revealed enrichment of several categories of genes important in protein kinase activity and mTOR cell signaling process which are related to OTA nephrocarcinogenicity.

  18. Postnatal exposure to trichloroethylene alters glutathione redox homeostasis, methylation potential, and neurotrophin expression in the mouse hippocampus.

    PubMed

    Blossom, Sarah J; Melnyk, Stepan; Cooney, Craig A; Gilbert, Kathleen M; James, S Jill

    2012-12-01

    Previous studies have shown that continuous exposure throughout gestation until the juvenile period to environmentally relevant doses of trichloroethylene (TCE) in the drinking water of MRL+/+ mice promoted adverse behavior associated with glutathione depletion in the cerebellum indicating increased sensitivity to oxidative stress. The purpose of this study was to extend our findings and further characterize the impact of TCE exposure on redox homeostasis and biomarkers of oxidative stress in the hippocampus, a brain region prone to oxidative stress. Instead of a continuous exposure, the mice were exposed to water only or two environmentally relevant doses of TCE in the drinking water postnatally from birth until 6 weeks of age. Biomarkers of plasma metabolites in the transsulfuration pathway and the transmethylation pathway of the methionine cycle were also examined. Gene expression of neurotrophins was examined to investigate a possible relationship between oxidative stress, redox imbalance and neurotrophic factor expression with TCE exposure. Our results show that hippocampi isolated from male mice exposed to TCE showed altered glutathione redox homeostasis indicating a more oxidized state. Also observed was a significant, dose dependent increase in glutathione precursors. Plasma from the TCE treated mice showed alterations in metabolites in the transsulfuration and transmethylation pathways indicating redox imbalance and altered methylation capacity. 3-Nitrotyrosine, a biomarker of protein oxidative stress, was also significantly higher in plasma and hippocampus of TCE-exposed mice compared to controls. In contrast, expression of key neurotrophic factors in the hippocampus (BDNF, NGF, and NT-3) was significantly reduced compared to controls. Our results demonstrate that low-level postnatal and early life TCE exposure modulates neurotrophin gene expression in the mouse hippocampus and may provide a mechanism for TCE-mediated neurotoxicity.

  19. Uptake and distribution of /sup 14/C during and following exposure to (/sup 14/C)methyl isocyanate

    SciTech Connect

    Ferguson, J.S.; Kennedy, A.L.; Stock, M.F.; Brown, W.E.; Alarie, Y.

    1988-06-15

    Guinea pigs were exposed to (/sup 14/C)methyl isocyanate (/sup 14/CH/sub 3/-NCO, /sup 14/C MIC) for periods of 1 to 6 hr at concentrations of 0.5 to 15 ppm. Arterial blood samples taken during exposure revealed immediate and rapid uptake of /sup 14/C. Clearance of /sup 14/C was then gradual over a period of 3 days. Similarly /sup 14/C was present in urine and bile immediately following exposure, and clearance paralleled that observed in blood. Guinea pigs fitted with a tracheal cannula and exposed while under anesthesia showed a reduced /sup 14/C uptake in blood indicating that most of the /sup 14/C MIC uptake in normal guinea pigs occurred from retention of this agent in the upper respiratory tract passages. In exposed guinea pigs /sup 14/C was distributed to all examined tissues. In pregnant female mice similarly exposed to /sup 14/C MIC, /sup 14/C was observed in all tissues examined following exposure including the uterus, placenta, and fetus. While the form of /sup 14/C distributed in blood and tissues has not yet been identified, these findings may help to explain the toxicity of MIC or MIC reaction products on organs other than the respiratory tract, as noted by several investigators.

  20. Maternal Arsenic Exposure, Arsenic Methylation Efficiency, and Birth Outcomes in the Biomarkers of Exposure to ARsenic (BEAR) Pregnancy Cohort in Mexico

    PubMed Central

    Laine, Jessica E.; Bailey, Kathryn A.; Rubio-Andrade, Marisela; Olshan, Andrew F.; Smeester, Lisa; Drobná, Zuzana; Herring, Amy H.; Stýblo, Miroslav; García-Vargas, Gonzalo G.

    2014-01-01

    Background: Exposure to inorganic arsenic (iAs) from drinking water is a global public health problem, yet much remains unknown about the extent of exposure in susceptible populations. Objectives: We aimed to establish the Biomarkers of Exposure to ARsenic (BEAR) prospective pregnancy cohort in Gómez Palacio, Mexico, to better understand the effects of iAs exposure on pregnant women and their children. Methods: Two hundred pregnant women were recruited for this study. Concentrations of iAs in drinking water (DW-iAs) and maternal urinary concentrations of iAs and its monomethylated and dimethylated metabolites (MMAs and DMAs, respectively) were determined. Birth outcomes were analyzed for their relationship to DW-iAs and to the concentrations and proportions of maternal urinary arsenicals. Results: DW-iAs for the study subjects ranged from < 0.5 to 236 μg As/L. More than half of the women (53%) had DW-iAs that exceeded the World Health Organization’s recommended guideline of 10 μg As/L. DW-iAs was significantly associated with the sum of the urinary arsenicals (U-tAs). Maternal urinary concentrations of MMAs were negatively associated with newborn birth weight and gestational age. Maternal urinary concentrations of iAs were associated with lower mean gestational age and newborn length. Conclusions: Biomonitoring results demonstrate that pregnant women in Gómez Palacio are exposed to potentially harmful levels of DW-iAs. The data support a relationship between iAs metabolism in pregnant women and adverse birth outcomes. The results underscore the risks associated with iAs exposure in vulnerable populations. Citation: Laine JE, Bailey KA, Rubio-Andrade M, Olshan AF, Smeester L, Drobná Z, Herring AH, Stýblo M, García-Vargas GG, Fry RC. 2015. Maternal arsenic exposure, arsenic methylation efficiency, and birth outcomes in the Biomarkers of Exposure to ARsenic (BEAR) pregnancy cohort in Mexico. Environ Health Perspect 123:186–192; http://dx.doi.org/10

  1. Photochemistry of alkyl bromides trapped in water ice films

    NASA Astrophysics Data System (ADS)

    Schrems, O.; Okaikwei, B.; Bluszcz, Th.

    2012-04-01

    Photochemical reactions of atmospheric trace gases taking place at the surface of atmospheric ice particles and in bulk ice are important in stratospheric and tropospheric chemistry but also in polar and alpine snowpack chemistry. Consequently, the understanding of the uptake und incorporation of atmospheric trace gases in water ice as well as their interactions with water molecules is very important for the understanding of processes which occur in ice particles and at the air/ice interface. Reactive atmospheric trace gases trapped in ice are subject of photochemical reactions when irradiated with solar UV radiation. Among such compounds bromine species are highly interesting due to their potential of depleting ozone both in the stratosphere and troposphere. Organic bromine gases can carry bromine to the stratosphere. Methyl bromide (CH3Br) is the largest bromine carrier to the stratosphere. It has both natural and anthropogenic sources. In this contribution we will present the results of our laboratory studies of alkyl bromides (methyl, bromide (CH3Br), dimethyl bromide (CH2Br2), n-propyl bromide (C3H7Br), 1,2-dibromoethane C2H4Br2)), trapped in water ice. We have simulated the UV photochemistry of these brominated alkanes isolated in ice films kept at 16 K and for comparison in solid argon matrices. The photoproducts formed in the ice have been identified by means of FTIR spectroscopy. Reflection absorption infrared spectroscopy (RAIRS) is especially useful to study nascent ice surfaces, kinetics of adsorption/decomposition, and heterogeneous catalysis. Among the observed photoproducts we could identify carbon monoxide and carbon dioxide for each alkyl bromide studied. The photoproduct HBr is dissociated in the bulk ice. Based on the experimental observations possible reaction mechanisms will be discussed.

  2. Trivalent methylated arsenical-induced phosphatidylserine exposure and apoptosis in platelets may lead to increased thrombus formation

    SciTech Connect

    Bae, Ok-Nam; Lim, Kyung-Min; Chung, Jin-Ho

    2009-09-01

    Trivalent methylated metabolites of arsenic, monomethylarsonous acid (MMA{sup III}) and dimethylarsinous acid (DMA{sup III}), have been found highly reactive and toxic in various cells and in vivo animal models, suggesting their roles in the arsenic-associated toxicity. However, their effects on cardiovascular system including blood cells, one of the most important targets for arsenic toxicity, remain poorly understood. Here we found that MMA{sup III} and DMA{sup III} could induce procoagulant activity and apoptosis in platelets, which play key roles in the development of various cardiovascular diseases (CVDs) through excessive thrombus formation. In freshly isolated human platelets, treatment of MMA{sup III} resulted in phosphatidylserine (PS) exposure, a hallmark of procoagulant activation, accompanied by distinctive apoptotic features including mitochondrial membrane potential disruption, cytochrome c release, and caspase-3 activation. These procoagulant activation and apoptotic features were found to be mediated by the depletion of protein thiol and intracellular ATP, and flippase inhibition by MMA{sup III}, while the intracellular calcium increase or reactive oxygen species generation was not involved. Importantly, increased platelet procoagulant activity by MMA{sup III} resulted in enhanced blood coagulation and excessive thrombus formation in a rat in vivo venous thrombosis model. DMA{sup III} also induced PS-exposure with apoptotic features mediated by protein thiol depletion, which resulted in enhanced thrombin generation. In summary, we believe that this study provides an important evidence for the role of trivalent methylated arsenic metabolites in arsenic-associated CVDs, giving a novel insight into the role of platelet apoptosis in toxicant-induced cardiovascular toxicity.

  3. Photoinitiated electron transfer to selected physisorbed alkyl bromides: The effects of alkyl chain length on dissociation cross sections

    SciTech Connect

    Khan, K.A.; Camillone, N. III; Osgood, R.M. Jr.

    1999-06-01

    We report the results of measurements of the cross section as a function of wavelength (351, 248, and 193 nm) for photoinitiated dissociative electron attachment to three normal alkyl bromides [CH{sub 3}(CH{sub 2}){sub n{minus}1}Br, n=1, 2, and 3] physisorbed on GaAs(110). Upon UV exposure, the molecules undergo C{endash}Br bond cleavage due to a substrate-mediated electron-transfer process. The cross sections for all three molecules increase monotonically with decreasing wavelength. Our results suggest a {approximately}1 eV higher threshold for dissociation of ethyl and propyl bromide than for methyl bromide. A simple model of the electron-transfer process is employed to estimate the peak per-electron cross section for dissociative attachment in the monolayer. We find that the cross sections for the physisorbed molecules are approximately five times smaller than those for gas-phase molecules, due to a reduction in the lifetime of the molecular anion in the vicinity of the surface. In addition, we also find an increase in cross section with chain length very similar to that observed in the gas phase; the gas-phase behavior has been explained by an increase in the anion lifetime with chain length. Our results suggest that while quenching of the molecular anion at the surface is important, it does not eliminate the progression of anion lifetime with chain length. {copyright} {ital 1999 American Institute of Physics.}

  4. Long-term ambient particle exposures and blood DNA methylation age: findings from the VA normative aging study

    PubMed Central

    Nwanaji-Enwerem, Jamaji C.; Colicino, Elena; Trevisi, Letizia; Kloog, Itai; Just, Allan C.; Shen, Jincheng; Brennan, Kasey; Dereix, Alexandra; Hou, Lifang; Vokonas, Pantel; Schwartz, Joel; Baccarelli, Andrea A.

    2016-01-01

    Background Ambient particles have been shown to exacerbate measures of biological aging; yet, no studies have examined their relationships with DNA methylation age (DNAm-age), an epigenome-wide DNA methylation based predictor of chronological age. Objective We examined the relationship of DNAm-age with fine particulate matter (PM2.5), a measure of total inhalable particle mass, and black carbon (BC), a measure of particles from vehicular traffic. Methods We used validated spatiotemporal models to generate 1-year PM2.5 and BC exposure levels at the addresses of 589 older men participating in the VA Normative Aging Study with 1–3 visits between 2000 and 2011 (n = 1032 observations). Blood DNAm-age was calculated using 353 CpG sites from the Illumina HumanMethylation450 BeadChip. We estimated associations of PM2.5 and BC with DNAm-age using linear mixed effects models adjusted for age, lifestyle/environmental factors, and aging-related diseases. Results After adjusting for covariates, a 1-µg/m3 increase in PM2.5 (95% CI: 0.30, 0.75, P<0.0001) was significantly associated with a 0.52-year increase in DNAm-age. Adjusted BC models showed similar patterns of association (β = 3.02, 95% CI: 0.48, 5.57, P = 0.02). Only PM2.5 (β = 0.54, 95% CI: 0.24, 0.84, P = 0.0004) remained significantly associated with DNAm-age in two-particle models. Methylation levels from 20 of the 353 CpGs contributing to DNAm-age were significantly associated with PM2.5 levels in our two-particle models. Several of these CpGs mapped to genes implicated in lung pathologies including LZTFL1, PDLIM5, and ATPAF1. Conclusion Our results support an association of long-termambient particle levels with DNAm-age and suggest that DNAm-age is a biomarker of particle-related physiological processes. PMID:27453791

  5. Respiratory tract changes in guinea pigs, rats, and mice following a single six-hour exposure to methyl isocyanate vapor

    SciTech Connect

    Fowler, E.H.; Dodd, D.E.

    1987-06-01

    Groups of male and female Fischer 344 rats, B6C3F1 mice, and Hartley guinea pigs were exposed once for 6 hr to mean concentrations of 10.5, 5.4, 2.4, 1.0, or 0 (control) ppm of methyl isocyanate (MIC) vapor. Rats and mice were also exposed to 20.4 ppm of MIC. The majority of deaths occurred during postexposure days 1 through 3. The 6-hr LC/sub 50/ values were 6.1 ppm for rats, 12.2 ppm for mice, and 5.4 ppm for guinea pigs. Notable clinical observations during and immediately following MIC exposure were lacrimation, perinasal/perioral wetness, respiratory difficulty (e.g., mouth breathing), decreased activity, ataxia, and hypothermia. Body weight losses were common in all species following MIC exposures of 2.4 ppm or greater. Microscopic lesions included acute necrosis of the epithelial lining throughout the respiratory tract in animals that died shortly after exposure, coupled with congestion, edema, and inflammation. A microscopic lesion that appeared unique to guinea pigs was bronchiolitis obliterans. Additional microscopic lesions observed in some animals that died or were sacrificed at the end of the study (postexposure day 14) consisted of squamous metaplasia of respiratory epithelium in the nasal cavity, which extended into the larynx, trachea, and in some cases, the bronchi. In addition, epithelial regeneration throughout the tract and submucosal fibroplasia in the trachea, bronchi, and bronchioles were observed, the latter lesion being primarily confined to rodents. Only in guinea pigs were there lesions in the 1.0 ppm group attributed to MIC exposure. In conclusion, guinea pigs were more sensitive to the MIC vapor than were rats, which were in turn more sensitive than mice.

  6. Exposure to methyl tert-butyl ether, benzene, and total hydrocarbons at the Singapore-Malaysia causeway immigration checkpoint

    SciTech Connect

    Tan, C.; Ong, H.Y.; Kok, P.W.

    1996-12-31

    The primary aim of this study was to determine the extent and levels of exposure to volatile organic compounds (VOCs) from automobile emissions in a group of immigration officers at a busy cross-border checkpoint. A majority (80%) of the workers monitored were exposed to benzene at levels between 0.01 and 0.5 ppm, with only 1.2% exceeding the current Occupational Safety and Health Administration occupational exposure limit of 1 ppm. The geometric mean (GM) concentrations of 8-hr time-weighted average exposure were 0.03 ppm, 0.9 ppm, and 2.46 ppm for methyl-tert-butyl ether (MTBE), benzene, and total hydrocarbons (THC), respectively. The highest time-weighted average concentrations measured were 1.05 ppm for MTBE, 2.01 ppm for benzene, and 34 ppm for THC. It was found that motorbikes emitted a more significant amount of pollutants compared with motor cars. On average, officers at the motorcycle booths were exposed to four to five times higher levels of VOCs (GMs of 0.07 ppm, 0.23 ppm, and 4.7 ppm for MTBE, benzene, and THC) than their counterparts at the motor car booths (GMs of 0.01 ppm, 0.05 ppm, and 1.5 ppm). The airborne concentrations of all three pollutants correlated with the flow of vehicle traffic. Close correlations were also noted for the concentrations in ambient air for the three pollutants measured. Benzene and MTBE had a correlation coefficient of 0.97. The overall findings showed that the concentrations of various VOCs were closely related to the traffic density, suggesting that they were from a common source, such as exhaust emissions from the vehicles. The results also indicated that although benzene, MTBE, and THC are known to be volatile, a significant amount could still be detected in the ambient environment, thus contributing to our exposure to these compounds. 4 refs., 6 figs.

  7. Biological effects of short-term, high-concentration exposure to methyl isocyanate. II. Blood chemistry and hematologic evaluations

    SciTech Connect

    Troup, C.M.; Dodd, D.E.; Fowler, E.H.; Frank, F.R.

    1987-06-01

    Human, rat, and guinea pig packed erythrocytes exposed to 100, 500, or 1000 ppm of methyl isocyanate (MIC) vapor in vitro showed a concentration-related inhibition of cholinesterase (ChE) activity. Rat and guinea pig packed erythrocytes showed an almost complete inhibition of ChE activity at 2000 ppm. In vitro exposures of human and guinea pig blood to 1000 or 2000 ppm of MIC vapor resulted in qualitative alterations in the electrophoretic mobility of hemoglobin (Hb) as measured by citrated agar electrophoresis. In rats and guinea pigs, neither IV injection of liquid MIC nor in vivo exposure to 1000 ppm of MIC by inhalation resulted in any inhibition of erythrocyte ChE activity or alteration in Hb electrophoretic mobility. As a result of these observations, it was concluded that neither ChE inhibition nor structural alteration of Hb were major contributing factors to death resulting from MIC exposure. Rats and guinea pigs receiving IV injections of liquid MIC showed an increase in creatine kinase (CK) levels. This increase could not be attributed to a specific isoenzyme of CK by ion exchange chromatography. Rats exposed to 100, 600, or 1000 ppm of MIC and guinea pigs exposed to 25, 125, or 225 ppm of MIC and bled immediately following a 15-min exposure or at 1, 2, 4, or 16 hr postexposure had the following alterations in blood parameters: (a) an increase in CK, (b) increases in hemoglobin concentration and hematocrit, (c) reticulocytosis (rats only), (d) neutrophilia, (e) a decrease in blood pH and PO/sub 2/, and (f) an increase in blood PCO/sub 2/. These findings indicate the occurrence of generalized hypoxic injury with concomitant pathophysiologic alterations, e.g., increases in hemoglobin and hematocrit concentrations.

  8. Viscosity and density of some lower alkyl chlorides and bromides

    SciTech Connect

    Rutherford, W.M.

    1988-07-01

    A high-pressure capillary viscometer, used previously to measure the viscosity of methyl chloride was rebuilt to eliminate the first-order dependence of the measured viscosity on the value assumed for the density of the fluid being investigated. At the same time, the system was arranged so that part of the apparatus could be used to measure density by a volumetric displacement technique. Viscosity and density were measured for ethyl chloride, 1-chloropropane, 1-chlorobutane, methyl bromide, ethyl bromide, and 1-bromopropane. The temperature and pressure ranges of the experiments were 20-150 /sup 0/C and 0.27-6.99 MPa, respectively. The accuracy of the viscosity measurements was estimated to be +-1% and of the density measurements, +-0.2%.

  9. Environmental arsenic exposure and DNA methylation of the tumor suppressor gene p16 and the DNA repair gene MLH1: effect of arsenic metabolism and genotype.

    PubMed

    Hossain, Mohammad Bakhtiar; Vahter, Marie; Concha, Gabriela; Broberg, Karin

    2012-11-01

    Arsenic is carcinogenic, possibly partly through epigenetic mechanisms. We evaluated the effects of arsenic exposure and metabolism on DNA methylation. Arsenic exposure and methylation efficiency in 202 women in the Argentinean Andes were assessed from concentrations of arsenic metabolites in urine (inorganic arsenic, methylarsonic acid [MMA], and dimethylarsinic acid [DMA]), measured by HPLC-ICPMS. Methylation of CpGs of the tumor suppressor gene p16, the DNA repair gene MLH1, and the repetitive elements LINE1 was measured by PCR pyrosequencing of blood DNA. Genotyping (N = 172) for AS3MT was performed using Sequenom™, and gene expression (N = 90) using Illumina DirectHyb HumanHT-12 v3.0. Median arsenic concentration in urine was 230 μg L(-1) (range 10.1-1251). In linear regression analysis, log(2)-transformed urinary arsenic concentrations were positively associated with methylation of p16 (β = 0.14, P = 0.0028) and MLH1 (β = 0.28, P = 0.0011), but not with LINE1. Arsenic concentrations were of borderline significance negatively correlated with expression of p16 (r(s) = -0.20; P = 0.066)), but not with MLH1. The fraction of inorganic arsenic was positively (β = 0.026; P = 0.010) and DMA was negatively (β = -0.017, P = 0.043) associated with p16 methylation with no effect of MMA. Carriers of the slow-metabolizing AS3MT haplotype were associated with more p16 methylation (P = 0.022). Arsenic exposure was correlated with increased methylation, in blood, of genes encoding enzymes that suppress carcinogenesis, and the arsenic metabolism efficiency modified the degree of epigenetic alterations.

  10. Crystal structure of 2,6-bis­(2-hy­droxy-5-methyl­phen­yl)-4-phenyl­pyridinium bromide di­chloro­methane hemisolvate hemihydrate

    PubMed Central

    Mankaev, Badma N.; Zaitsev, Kirill V.; Karlov, Sergey S.; Egorov, Mikhail P.; Churakov, Andrei V.

    2015-01-01

    The asymmetric unit in the structure of the title compound, C25H22NO2 +·Br −·0.5CH2Cl2·0.5H2O, comprises two pseudosymmetry-related cations, two bromide anions, a di­chloro­methane molecule and a water mol­ecule of solvation. The two independent cations are conformationally similar with the comparative dihedral angles between the central pyridine ring and the three benzene substituent rings being 3.0 (2), 36.4 (1) and 24.2 (1)°, and 3.7 (2), 36.5 (1) and 24.8 (1)°, respectively. In the crystal, the cations, anions and water mol­ecules are linked through O—H⋯O and O—H⋯Br hydrogen bonds, forming an insular unit. Within the cations there are also intra­molecular N—H⋯O hydrogen bonds. Adjacent centrosymmetrically related aggregates are linked by π–π stacking inter­actions between the pyridine ring and a benzene ring in both cations [ring-centroid separations = 3.525 (3) and 3.668 (3) Å], forming chains extending across the ac diagonal. Voids between these chains are filled by dichloromethane molecules. PMID:26870547

  11. Influence of bromide on the performance of the amphipod Hyalella azteca in reconstituted waters

    USGS Publications Warehouse

    Ivey, Chris D.; Ingersoll, Christopher G.

    2016-01-01

    Poor performance of the amphipod Hyalella azteca has been observed in exposures using reconstituted waters. Previous studies have reported success in H. azteca water-only exposures with the addition of relatively high concentrations of bromide. The present study evaluated the influence of lower environmentally representative concentrations of bromide on the response ofH. azteca in 42-d water-only exposures. Improved performance of H. azteca was observed in reconstituted waters with >0.02 mg Br/L.

  12. Methyl chloroform

    SciTech Connect

    Wray, T.K.

    1994-04-01

    Methyl chloroform is identified as a Class 1 ozone-depleting substance under Title VI of the CAA Amendments. On Nov. 30, 1993, EPA ordered the phaseout of Class 1 ozone-depleting substances -- chlorofluorocarbons (CFCs), halons, carbon tetrachloride and methyl chloroform -- by Jan. 1, 1996. Methyl chloroform and other Class 1 substances may be used after the dead-line if sources can be found through recycling or existing inventories. Methyl chloroform is listed as a hazardous air pollutant under CAA. It also is a SARA Title III, Sec. 313 compound with a reportable quantity of 1,000 pounds. OSHA and the American Conference of Government Industrial Hygienists have set 350 ppm as the time-weighted average airborne exposure level for methyl chloroform. NIOSH lists its immediately dangerous to life or health'' concentration as 1,000 parts per million. DOT identifies the substance as a hazardous material, Class 6.1 (poison).

  13. IMBALANCE OF DNA METHYLATION, BOTH HYPERMETHYLATION AND HYPOMETHYLATION, OCCUR AFTER EXPOSURE OF HUMAN CELLS TO NANOMOLAR CONCENTRATIONS OF ARSENITE IN CULTURE.

    EPA Science Inventory

    Imbalance of DNA methylation, BOTH hypermethylation and hypomethylation, occur after exposure of human cells to nanomolar concentrations of arsenite in culture.

    We and others have hypothesized that a mechanism of arsenic carcinogenesis could involve alteration of DNA methy...

  14. Histologic and histomorphometric changes of testis following oral exposure to methyl tertiary-butyl ether in adult rat.

    PubMed

    Gholami, S; Ansari-Lari, M; Khalili, L

    2015-01-01

    Methyl tertiary-butyl ether (MTBE) is used to reduce carbon monoxide and ozone in urban air and to boost fuel octane. There is a lack of knowledge in the literature about the histomorphometric changes of the testis following exposure to MTBE. Therefore, this experimental study was performed to determine the effect of oral exposure to MTBE on histologic and histomorphometric changes of testis in adult rat. A total of 25 adult male Sprague-Dawley rats were randomly divided into five equal experimental groups: control, almond oil and three treatment groups which received 400, 800 and 1600 mg/kg/day MTBE in almond oil by gavages for 30 consecutive days. Histomorphometric analysis showed no significant difference in absolute and relative testis weight, connective tissue thickness, germinal epithelium height, tunica albuginea thickness and Sertoli cell numbers between experimental groups (P>0.05). However, trend analysis showed that the seminiferous tubule diameter increased and interstitial cell numbers as well as spermatocyte and spermatid cell numbers decreased significantly in MTBE treated groups (P<0.05). It may be concluded that MTBE could exert adverse effects on spermatogenic cells in adult rat. Whether the observed changes in the present study are due to the direct effect of MTBE via passing blood-testis barrier or its indirect effect through another mechanism should be elucidated in future studies. PMID:27175191

  15. Dietary exposure of the red-crowned crane (Grus japonensis) to total and methyl mercury in Zhalong Wetland, northeastern China.

    PubMed

    Luo, Jinming; Ye, Yajie; Wang, Yongjie

    2014-06-01

    To determine the dietary exposure of the migratory red-crowned crane to mercury (Hg), this study analyzed the concentrations of total mercury (T-Hg) and methyl mercury (MeHg) in its prey, i.e., reeds and three aquatic animal families (Perccottus glenni Dybowski, Cybister japonicus Sharp, and Viviparidae) in northeastern China. Results indicated that the Hg concentration in Zhalong Wetland was elevated through the food chain, and the prey of the red-crowned crane contained measurable levels of T-Hg and MeHg. In prey tissues, MeHg was the main form of the Hg element and accounted for 61% of total Hg concentration in Viviparidae, 58% in C. japonicus Sharp, and 85% in P. glenni Dybowski. The highest T-Hg and MeHg concentrations ranged from 1.66 to 3.89 ppm and from 1.12 to 2.67 ppm, respectively, and they were detected in the feathers of the red-crowned cranes. The lowest T-Hg concentration was determined in the excretions of wild red-crowned cranes at 0.21 ppm; furthermore, the content of MeHg was below the detection limit. In Zhalong Wetland, the level of dietary exposure of the population of red-crowned cranes to Hg is below the threshold of Hg toxicity. Moreover, eggshells are suitable indicators of Hg risk levels to the red-crowned crane. PMID:24793423

  16. Maternal exposure to fluoxetine during gestation and lactation affects the DNA methylation programming of rat's offspring: modulation by folic acid supplementation.

    PubMed

    Toffoli, L V; Rodrigues, G M; Oliveira, J F; Silva, A S; Moreira, E G; Pelosi, G G; Gomes, M V

    2014-05-15

    Fluoxetine is an antidepressant that has been largely used for treatment of depression in pregnancy. In the present study we evaluated the effects of the exposure to fluoxetine during gestation and lactation on DNA methylation of rat brain regions. Female Wistar rats were treated with 5mg/kg of fluoxetine during pregnancy and lactation. In order to assess the effects of fluoxetine in the context of maternal folic acid supplementation we performed an additional combined treatment composed by folic acid (8 mg/kg/day) and fluoxetine (5 mg/kg/day). On the postnatal day 22, male rats were euthanized and hippocampus, cortex, hypothalamus, and periaqueductal gray area were removed. Global DNA methylation was quantified using a high-throughput ELISA-based method. Neurofunctional changes were addressed using validated behavioral tests: hot plate, elevated plus maze and open field. A decrease in the global DNA methylation profile of hippocampus was associated to the exposure to fluoxetine, whereas an increase in methylation was observed in cortex. The combined treatment induced an increase in the methylation of hippocampus indicating the potential of folic acid to modulate this epigenetic alteration. Increase in the latency to the thermal nociceptive response was observed in animals exposed to fluoxetine whereas this effect was abolished in animals from the combined treatment. In summary we demonstrated that exposure to fluoxetine during gestation and lactation affect the DNA methylation of brain and the nociceptive response of rats. Furthermore our data reveal the potential of folic acid to modulate epigenetic and functional changes induced by early exposure to fluoxetine. PMID:24583191

  17. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... internal pressure of 130 psig without leakage or permanent distortion. Vapor pressure of the contents must... pressure of 140 psig without leakage or permanent distortion. Vapor pressure of the contents must not... tinplate or lined with suitable material and must have concave or pressure ends. (d) Cylinders,...

  18. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... internal pressure of 130 psig without leakage or permanent distortion. Vapor pressure of the contents must... pressure of 140 psig without leakage or permanent distortion. Vapor pressure of the contents must not... tinplate or lined with suitable material and must have concave or pressure ends. (d) Cylinders,...

  19. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... internal pressure of 130 psig without leakage or permanent distortion. Vapor pressure of the contents must... pressure of 140 psig without leakage or permanent distortion. Vapor pressure of the contents must not... tinplate or lined with suitable material and must have concave or pressure ends. (d) Cylinders,...

  20. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... capable of withstanding an internal pressure of 130 psig without leakage or permanent distortion. Vapor... withstanding an internal pressure of 140 psig without leakage or permanent distortion. Vapor pressure of...

  1. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... capable of withstanding an internal pressure of 130 psig without leakage or permanent distortion. Vapor... withstanding an internal pressure of 140 psig without leakage or permanent distortion. Vapor pressure of...

  2. Probabilistic Exposure Assessment for Applicators during Treatment of the Fungicide Kresoxim-methyl on an Apple Orchard by a Speed Sprayer.

    PubMed

    Kim, Eunhye; Moon, Joon-Kwan; Choi, Hoon; Kim, Jeong-Han

    2015-12-01

    Probabilistic exposure and risk assessment of kresoxim-methyl were conducted for agricultural applicators during preparation of spray suspension and application with a speed sprayer on an apple orchard. The preparation and application of 1000 L of spray suspension were repeated 30 times. Several exposure matrices, including patches, cotton gloves, socks, masks, and XAD-2 resin, were used to measure the potential exposure for workers. The analytical methods were fully validated to guarantee the precision and accuracy of analysis. The exposure amount on hands for mixer/loader was 0.7 mg [95% confidence interval (CI) from 0.02 to 2.4], taking 0.0005% (95% CI from 1.2 × 10(-5) to 0.001) of total prepared active ingredient. During application of kresoxim-methyl, the amount of dermal exposure was 17.5 mg (95% CI from 9.3 to 28.9), corresponding to 0.010% (95% CI from 0.006 to 0.017) of total applied active ingredient. The major exposure parts of the body were thighs and shins, with correlation coefficients of 0.53 and 0.43, respectively. The inhalation exposure during application were estimated as 6.8 ng (95% CI from 0.4 to 17.0), being 0.04% (95% CI from 0.004 to 0.06) of the dermal exposure. The calculated absorbable quantities of exposures for mixer/loader and applicator were 2.1 × 10(-4) mg/day (95% CI from 5.0 × 10(-6) to 7.2 × 10(-4)) and 2.3 mg/day (95% CI from 1.2 to 3.8), respectively. For risk assessment, the margin of safety of all working activities was much higher than 1, indicating that the possibility of risk to kresoxim-methyl was unlikely. PMID:26492351

  3. Probabilistic Exposure Assessment for Applicators during Treatment of the Fungicide Kresoxim-methyl on an Apple Orchard by a Speed Sprayer.

    PubMed

    Kim, Eunhye; Moon, Joon-Kwan; Choi, Hoon; Kim, Jeong-Han

    2015-12-01

    Probabilistic exposure and risk assessment of kresoxim-methyl were conducted for agricultural applicators during preparation of spray suspension and application with a speed sprayer on an apple orchard. The preparation and application of 1000 L of spray suspension were repeated 30 times. Several exposure matrices, including patches, cotton gloves, socks, masks, and XAD-2 resin, were used to measure the potential exposure for workers. The analytical methods were fully validated to guarantee the precision and accuracy of analysis. The exposure amount on hands for mixer/loader was 0.7 mg [95% confidence interval (CI) from 0.02 to 2.4], taking 0.0005% (95% CI from 1.2 × 10(-5) to 0.001) of total prepared active ingredient. During application of kresoxim-methyl, the amount of dermal exposure was 17.5 mg (95% CI from 9.3 to 28.9), corresponding to 0.010% (95% CI from 0.006 to 0.017) of total applied active ingredient. The major exposure parts of the body were thighs and shins, with correlation coefficients of 0.53 and 0.43, respectively. The inhalation exposure during application were estimated as 6.8 ng (95% CI from 0.4 to 17.0), being 0.04% (95% CI from 0.004 to 0.06) of the dermal exposure. The calculated absorbable quantities of exposures for mixer/loader and applicator were 2.1 × 10(-4) mg/day (95% CI from 5.0 × 10(-6) to 7.2 × 10(-4)) and 2.3 mg/day (95% CI from 1.2 to 3.8), respectively. For risk assessment, the margin of safety of all working activities was much higher than 1, indicating that the possibility of risk to kresoxim-methyl was unlikely.

  4. Phenyltrimethylammonium Salts as Methylation Reagents in the Nickel-Catalyzed Methylation of C-H Bonds.

    PubMed

    Uemura, Takeshi; Yamaguchi, Mao; Chatani, Naoto

    2016-02-24

    Methylation of C(sp(2))-H bonds was achieved through the Ni(II)-catalyzed reaction of benzamides with phenyltrimethylammonium bromide or iodide as the source of the methyl group. The reaction has a broad scope and shows high functional-group compatibility. The reaction is also applicable to the methylation of C(sp(3))-H bonds in aliphatic amides. PMID:26821872

  5. Gestational exposure to diethylstilbestrol alters cardiac structure/function, protein expression and DNA methylation in adult male mice progeny

    SciTech Connect

    Haddad, Rami; Kasneci, Amanda; Mepham, Kathryn; Sebag, Igal A.; and others

    2013-01-01

    Pregnant women, and thus their fetuses, are exposed to many endocrine disruptor compounds (EDCs). Fetal cardiomyocytes express sex hormone receptors making them potentially susceptible to re-programming by estrogenizing EDCs. Diethylstilbestrol (DES) is a proto-typical, non-steroidal estrogen. We hypothesized that changes in adult cardiac structure/function after gestational exposure to the test compound DES would be a proof in principle for the possibility of estrogenizing environmental EDCs to also alter the fetal heart. Vehicle (peanut oil) or DES (0.1, 1.0 and 10.0 μg/kg/da.) was orally delivered to pregnant C57bl/6n dams on gestation days 11.5–14.5. At 3 months, male progeny were left sedentary or were swim trained for 4 weeks. Echocardiography of isoflurane anesthetized mice revealed similar cardiac structure/function in all sedentary mice, but evidence of systolic dysfunction and increased diastolic relaxation after swim training at higher DES doses. The calcium homeostasis proteins, SERCA2a, phospholamban, phospho-serine 16 phospholamban and calsequestrin 2, are important for cardiac contraction and relaxation. Immunoblot analyses of ventricle homogenates showed increased expression of SERCA2a and calsequestrin 2 in DES mice and greater molecular remodeling of these proteins and phospho-serine 16 phospholamban in swim trained DES mice. DES increased cardiac DNA methyltransferase 3a expression and DNA methylation in the CpG island within the calsequestrin 2 promoter in heart. Thus, gestational DES epigenetically altered ventricular DNA, altered cardiac function and expression, and reduced the ability of adult progeny to cardiac remodel when physically challenged. We conclude that gestational exposure to estrogenizing EDCs may impact cardiac structure/function in adult males. -- Highlights: ► Gestational DES changes cardiac SERCA2a and CASQ2 expression. ► Echocardiography identified systolic dysfunction and increased diastolic relaxation. ► DES

  6. DNA methylation alterations in response to prenatal exposure of maternal cigarette smoking: A persistent epigenetic impact on health from maternal lifestyle?

    PubMed

    Nielsen, Christina H; Larsen, Agnete; Nielsen, Anders L

    2016-02-01

    Despite increased awareness, maternal cigarette smoking during pregnancy continues to be a common habit causing risk for numerous documented negative health consequences in the exposed children. It has been proposed that epigenetic mechanisms constitute the link between prenatal exposure to maternal cigarette smoking (PEMCS) and the diverse pathologies arising in later life. We here review the current literature, focusing on DNA methylation. Alterations in the global DNA methylation patterns were observed after exposure to maternal smoking during pregnancy in placenta, cord blood and buccal epithelium tissue. Further, a number of specific genes exemplified by CYP1A1, AhRR, FOXP3, TSLP, IGF2, AXL, PTPRO, C11orf52, FRMD4A and BDNF are shown to have altered DNA methylation patterns in at least one of these tissue types due to PEMCS. Investigations showing persistence and indications of trans-generational inheritance of DNA methylation alterations induced by smoking exposure are also described. Further, smoking-induced epigenetic manifestations can be both tissue-dependent and gender-specific which show the importance of addressing the relevant sex, tissue and cell types in the future studies linking specific epigenetic alterations to disease development. Moreover, the effect of paternal cigarette smoking and second-hand smoke exposure is documented and accordingly not to be neglected in future investigations and data evaluations. We also outline possible directions for the future research to address how DNA methylation alterations induced by maternal lifestyle, exemplified by smoking, have direct consequences for fetal development and later in life health and behavior of the child. PMID:25480659

  7. Recovery study of cholinesterases and neurotoxic signs in the non-target freshwater invertebrate Chilina gibbosa after an acute exposure to an environmental concentration of azinphos-methyl.

    PubMed

    Cossi, Paula Fanny; Beverly, Boburg; Carlos, Luquet; Kristoff, Gisela

    2015-10-01

    Azinphos-methyl belongs to the class of organophosphate insecticides which are recognized for their anticholinesterase action. It is one of the most frequently used insecticides in the Upper Valley of Río Negro and Río Neuquén in Argentina, where agriculture represents the second most important economic activity. It has been detected in water from this North Patagonian region throughout the year and the maximum concentration found was 22.48 μg L(-1) during the application period. Chilina gibbosa is a freshwater gastropod widely distributed in South America, particularly in Patagonia, Argentina and in Southern Chile. Toxicological studies performed with C. gibbosa in our laboratory have reported neurotoxicity signs and cholinesterase inhibition after exposure to azinphos-methyl for 48 h. Recovery studies together with characterization of the enzyme and sensitivity of the enzyme to pesticides can improve the toxicological evaluation. However, little is known about recovery patterns in organisms exposed to organophosphates. The aim of the present work was to evaluate the recovery capacity (during 21 days in pesticide-free water) of cholinesterase activity and neurotoxicity in C. gibbosa after 48 h of exposure to azinphos-methyl. Also, lethality and carboxylesterase activity were registered during the recovery period. Regarding enzyme activities, after a 48-h exposure to 20 μg L(-1) of azinphos-methyl, cholinesterases showed an inhibition of 85% with respect to control, while carboxylesterases were not affected. After 21 days in pesticide-free water, cholinesterases continued to be inhibited (70%). Severe neurotoxicity signs were observed after exposure: 82% of the snails presented lack of adherence to vessels, 11% showed weak adherence, and 96% exhibited an abnormal protrusion of the head-foot region from shell. After 21 days in pesticide-free water, only 15% of the snails presented severe signs of neurotoxicity. However, during the recovery period significant

  8. Recovery study of cholinesterases and neurotoxic signs in the non-target freshwater invertebrate Chilina gibbosa after an acute exposure to an environmental concentration of azinphos-methyl.

    PubMed

    Cossi, Paula Fanny; Beverly, Boburg; Carlos, Luquet; Kristoff, Gisela

    2015-10-01

    Azinphos-methyl belongs to the class of organophosphate insecticides which are recognized for their anticholinesterase action. It is one of the most frequently used insecticides in the Upper Valley of Río Negro and Río Neuquén in Argentina, where agriculture represents the second most important economic activity. It has been detected in water from this North Patagonian region throughout the year and the maximum concentration found was 22.48 μg L(-1) during the application period. Chilina gibbosa is a freshwater gastropod widely distributed in South America, particularly in Patagonia, Argentina and in Southern Chile. Toxicological studies performed with C. gibbosa in our laboratory have reported neurotoxicity signs and cholinesterase inhibition after exposure to azinphos-methyl for 48 h. Recovery studies together with characterization of the enzyme and sensitivity of the enzyme to pesticides can improve the toxicological evaluation. However, little is known about recovery patterns in organisms exposed to organophosphates. The aim of the present work was to evaluate the recovery capacity (during 21 days in pesticide-free water) of cholinesterase activity and neurotoxicity in C. gibbosa after 48 h of exposure to azinphos-methyl. Also, lethality and carboxylesterase activity were registered during the recovery period. Regarding enzyme activities, after a 48-h exposure to 20 μg L(-1) of azinphos-methyl, cholinesterases showed an inhibition of 85% with respect to control, while carboxylesterases were not affected. After 21 days in pesticide-free water, cholinesterases continued to be inhibited (70%). Severe neurotoxicity signs were observed after exposure: 82% of the snails presented lack of adherence to vessels, 11% showed weak adherence, and 96% exhibited an abnormal protrusion of the head-foot region from shell. After 21 days in pesticide-free water, only 15% of the snails presented severe signs of neurotoxicity. However, during the recovery period significant

  9. Electronic structure mapping of branching states in poly[methyl(phenyl)silane] upon exposure to UV radiation

    NASA Astrophysics Data System (ADS)

    Schauer, František; Tkáč, Lukáš; Ožvoldová, Miroslava; Nadáždy, Vojtech; Gmucová, Katarána; Végsö, Karol; Tkáčová, Miroslava; Chlpík, Juraj

    2016-02-01

    The origin of white photoluminescence in polysilanes has long been disputed, and this emission is closely connected with information recording in nanotechnologies. We elucidated UV degradation of an archetypal model polymer poly[methyl(phenyl)silane] by using a new method for electronic structure mapping of organic semiconductors, energy-resolved electrochemical impedance spectroscopy (ER-EIS) and photoluminescence spectroscopy. UV exposure at 345 nm resulted in two defect bands above the highest occupied molecular orbital (HOMO) in the energy region from -5.5 eV to -3.5 eV with respect to the zero vacuum energy level. The respective density of states was 1016 - 1017 cm-3eV-1, and the total integrated concentration was 0 - 1017 cm-3. The photoluminescence in the long-wavelength region gave wide bands with photon energies from 2.2 eV to 3.2 eV (corresponding to wavelengths from 600 nm to 390 nm). The observed bands were interpreted by assuming the formation of energetically distributed Si branching radiative states, whose distribution in the HOMO - lowest unoccupied molecular orbital (LUMO) gap was observed by using ER-EIS. The quantum efficiency of defect state formation increased from Φ(x)345 nm = 0.0045 to Φ(x)290 nm = 0.053. The obtained results may contribute to the production of effective polysilane nanomasks and to information recording.

  10. Exposure of methyl mercury in utero and the risk of neural tube defects in a Chinese population.

    PubMed

    Jin, Lei; Liu, Ming; Zhang, Le; Li, Zhiwen; Yu, Jingru; Liu, Jianmeng; Ye, Rrongwei; Chen, Laiguo; Ren, Aiguo

    2016-06-01

    To determine if exposure to methyl mercury (MeHg) in utero is associated with an elevated risk of neural tube defects (NTDs), we measured its concentration in the placentas of 36 anencephalic and 44 spina bifida cases, as well as in 50 healthy controls. The median MeHg concentration in NTD cases (0.49ng/g) was higher than that in controls (0.33ng/g). The crude and adjusted odds ratios (ORs) for a MeHg concentration above the median were 3.54 (95% confidence interval (CI), 1.68-7.49) and 3.64 (95% CI, 1.66-7.99), respectively. Both anencephaly and spina bifida subtypes had higher levels of MeHg than the controls. NTD risk increased for subjects in the second and third highest tertile of MeHg concentrations, with an OR of 2.24 (95% CI, 0.93-5.40) and 2.85 (95% CI, 1.17-6.94), respectively. In summary, higher placental levels of MeHg are associated with an elevated risk of NTDs. PMID:27049578

  11. DNA methyltransferases and stress-related genes expression in zebrafish larvae after exposure to heat and copper during reprogramming of DNA methylation

    PubMed Central

    Dorts, Jennifer; Falisse, Elodie; Schoofs, Emilie; Flamion, Enora; Kestemont, Patrick; Silvestre, Frédéric

    2016-01-01

    DNA methylation, a well-studied epigenetic mark, is important for gene regulation in adulthood and for development. Using genetic and epigenetic approaches, the present study aimed at evaluating the effects of heat stress and copper exposure during zebrafish early embryogenesis when patterns of DNA methylation are being established, a process called reprogramming. Embryos were exposed to 325 μg Cu/L from fertilization (<1 h post fertilization - hpf) to 4 hpf at either 26.5 °C or 34 °C, followed by incubation in clean water at 26.5 °C till 96 hpf. Significant increased mortality rates and delayed hatching were observed following exposure to combined high temperature and Cu. Secondly, both stressors, alone or in combination, significantly upregulated the expression of de novo DNA methyltransferase genes (dnmt3) along with no differences in global cytosine methylation level. Finally, Cu exposure significantly increased the expression of metallothionein (mt2) and heat shock protein (hsp70), the latter being also increased following exposure to high temperature. These results highlighted the sensitivity of early embryogenesis and more precisely of the reprogramming period to environmental challenges, in a realistic situation of combined stressors. PMID:27731414

  12. Alteration of Gene Expression, DNA Methylation, and Histone Methylation in Free Radical Scavenging Networks in Adult Mouse Hippocampus following Fetal Alcohol Exposure.

    PubMed

    Chater-Diehl, Eric J; Laufer, Benjamin I; Castellani, Christina A; Alberry, Bonnie L; Singh, Shiva M

    2016-01-01

    The molecular basis of Fetal Alcohol Spectrum Disorders (FASD) is poorly understood; however, epigenetic and gene expression changes have been implicated. We have developed a mouse model of FASD characterized by learning and memory impairment and persistent gene expression changes. Epigenetic marks may maintain expression changes over a mouse's lifetime, an area few have explored. Here, mice were injected with saline or ethanol on postnatal days four and seven. At 70 days of age gene expression microarray, methylated DNA immunoprecipitation microarray, H3K4me3 and H3K27me3 chromatin immunoprecipitation microarray were performed. Following extensive pathway analysis of the affected genes, we identified the top affected gene expression pathway as "Free radical scavenging". We confirmed six of these changes by droplet digital PCR including the caspase Casp3 and Wnt transcription factor Tcf7l2. The top pathway for all methylation-affected genes was "Peroxisome biogenesis"; we confirmed differential DNA methylation in the Acca1 thiolase promoter. Altered methylation and gene expression in oxidative stress pathways in the adult hippocampus suggests a novel interface between epigenetic and oxidative stress mechanisms in FASD. PMID:27136348

  13. Alteration of Gene Expression, DNA Methylation, and Histone Methylation in Free Radical Scavenging Networks in Adult Mouse Hippocampus following Fetal Alcohol Exposure

    PubMed Central

    Chater-Diehl, Eric J.; Castellani, Christina A.; Alberry, Bonnie L.; Singh, Shiva M.

    2016-01-01

    The molecular basis of Fetal Alcohol Spectrum Disorders (FASD) is poorly understood; however, epigenetic and gene expression changes have been implicated. We have developed a mouse model of FASD characterized by learning and memory impairment and persistent gene expression changes. Epigenetic marks may maintain expression changes over a mouse’s lifetime, an area few have explored. Here, mice were injected with saline or ethanol on postnatal days four and seven. At 70 days of age gene expression microarray, methylated DNA immunoprecipitation microarray, H3K4me3 and H3K27me3 chromatin immunoprecipitation microarray were performed. Following extensive pathway analysis of the affected genes, we identified the top affected gene expression pathway as “Free radical scavenging”. We confirmed six of these changes by droplet digital PCR including the caspase Casp3 and Wnt transcription factor Tcf7l2. The top pathway for all methylation-affected genes was “Peroxisome biogenesis”; we confirmed differential DNA methylation in the Acca1 thiolase promoter. Altered methylation and gene expression in oxidative stress pathways in the adult hippocampus suggests a novel interface between epigenetic and oxidative stress mechanisms in FASD. PMID:27136348

  14. Methylation of Exons 1D, 1F, and 1H of the Glucocorticoid Receptor Gene Promoter and Exposure to Adversity in Pre-School Aged Children

    PubMed Central

    Tyrka, Audrey R.; Parade, Stephanie H.; Eslinger, Nicole M.; Marsit, Carmen J.; Lesseur, Corina; Armstrong, David A.; Philip, Noah S.; Josefson, Brittney; Seifer, Ronald

    2016-01-01

    Epigenetic modifications to the genome are a key mechanism involved in the biological encoding of experience. Animal studies and a growing body of literature in humans have shown that early adversity is linked to methylation of the gene for the glucocorticoid receptor (GR) which is a key regulator of the hypothalamic-pituitary-adrenal (HPA) axis as well as a broad range of physiological systems including metabolic and immune function. One hundred eighty-four families participated, including n=74 with child welfare documentation of moderate-severe maltreatment in the past six months. Children ranged in age from 3 to 5 years, and were racially and ethnically diverse. Structured record review and interviews in the home were used to assess a history of maltreatment, other traumas, and contextual life stressors, and a composite variable assessed the number exposures to these adversities. Methylation of regions 1D, 1F, and 1H of the GR gene was measured via sodium bisulfite pyrosequencing. The composite measure of adversity was positively correlated with methylation at exons 1D and 1F in the promoter of NR3C1. Individual stress measures were significantly associated with a several CpG sites in these regions. GR gene methylation may be a mechanism of the bio-behavioral effects of adverse exposures in young children. PMID:25997773

  15. DNA methylation mediates the impact of exposure to prenatal maternal stress on BMI and central adiposity in children at age 13½ years: Project Ice Storm.

    PubMed

    Cao-Lei, Lei; Dancause, Kelsey N; Elgbeili, Guillaume; Massart, Renaud; Szyf, Moshe; Liu, Aihua; Laplante, David P; King, Suzanne

    2015-01-01

    Prenatal maternal stress (PNMS) in animals and humans predicts obesity and metabolic dysfunction in the offspring. Epigenetic modification of gene function is considered one possible mechanism by which PNMS results in poor outcomes in offspring. Our goal was to determine the role of maternal objective exposure and subjective distress on child BMI and central adiposity at 13½ years of age, and to test the hypothesis that DNA methylation mediates the effect of PNMS on growth. Mothers were pregnant during the January 1998 Quebec ice storm. We assessed their objective exposure and subjective distress in June 1998. At age 13½ their children were weighed and measured (n = 66); a subsample provided blood samples for epigenetic studies (n = 31). Objective and subjective PNMS correlated with central adiposity (waist-to-height ratio); only objective PNMS predicted body mass index (BMI). Bootstrapping analyses showed that the methylation level of genes from established Type-1 and -2 diabetes mellitus pathways showed significant mediation of the effect of objective PNMS on both central adiposity and BMI. However, the negative mediating effects indicate that, although greater objective PNMS predicts greater BMI and adiposity, this effect is dampened by the effects of objective PNMS on DNA methylation, suggesting a protective role of the selected genes from Type-1 and -2 diabetes mellitus pathways. We provide data supporting that DNA methylation is a potential mechanism involved in the long-term adaptation and programming of the genome in response to early adverse environmental factors.

  16. Genome-Wide DNA Methylation Profiling Reveals Epigenetic Changes in the Rat Nucleus Accumbens Associated With Cross-Generational Effects of Adolescent THC Exposure.

    PubMed

    Watson, Corey T; Szutorisz, Henrietta; Garg, Paras; Martin, Qammarah; Landry, Joseph A; Sharp, Andrew J; Hurd, Yasmin L

    2015-12-01

    Drug exposure during critical periods of development is known to have lasting effects, increasing one's risk for developing mental health disorders. Emerging evidence has also indicated the possibility for drug exposure to even impact subsequent generations. Our previous work demonstrated that adolescent exposure to Δ(9)-tetrahydrocannabinol (THC), the main psychoactive component of marijuana (Cannabis sativa), in a Long-Evans rat model affects reward-related behavior and gene regulation in the subsequent (F1) generation unexposed to the drug. Questions, however, remained regarding potential epigenetic consequences. In the current study, using the same rat model, we employed Enhanced Reduced Representation Bisulfite Sequencing to interrogate the epigenome of the nucleus accumbens, a key brain area involved in reward processing. This analysis compared 16 animals with parental THC exposure and 16 without to characterize relevant systems-level changes in DNA methylation. We identified 1027 differentially methylated regions (DMRs) associated with parental THC exposure in F1 adults, each represented by multiple CpGs. These DMRs fell predominantly within introns, exons, and intergenic intervals, while showing a significant depletion in gene promoters. From these, we identified a network of DMR-associated genes involved in glutamatergic synaptic regulation, which also exhibited altered mRNA expression in the nucleus accumbens. These data provide novel insight into drug-related cross-generational epigenetic effects, and serve as a useful resource for investigators to explore novel neurobiological systems underlying drug abuse vulnerability.

  17. Genome wide analysis of DNA methylation and gene expression changes in the mouse lung following subchronic arsenate exposure

    EPA Science Inventory

    Alterations in DNA methylation have been proposed as a mechanism for the complex toxicological effects of arsenic. In this study, whole genome DNA methylation and gene expression changes were evaluated in lungs from female mice exposed for 90 days to 50 ppm arsenate (As) in drink...

  18. Adult glucocorticoid exposure leads to transcriptional and DNA methylation changes in nuclear steroid receptors in the hippocampus and kidney of mouse male offspring.

    PubMed

    Petropoulos, Sophie; Matthews, Stephen G; Szyf, Moshe

    2014-02-01

    Synthetic glucocorticoids (sGCs) are commonly prescribed for the management of inflammatory and endocrine disorders. However, nothing is known regarding the effects of sGC on adult germline methylome and whether these effects can be transmitted to the next generation. We hypothesized that administration of sGC to adult male mice alters DNA methylation in mature sperm and modifies the transcription and methylation of steroid receptors in male F1 offspring. Adult C57BL/6 males (n = 10/group) were injected on five consecutive days with 1 mg/kg sGC (i.e., dexamethasone) or vehicle and euthanized 35 or 60 days after initial treatment or bred with control females (60 days postinitial treatment; n = 5/group). A significant increase in global non-CpG methylation was observed in F0 sperm 60 days following sGC treatment. In the hippocampus and kidney of Postnatal Day 50 (PND50) and PND240 male offspring derived from fathers exposed to sGC, significant differences in mineralocorticoid receptor (Nr3c2; Mr), estrogen alpha receptor (Nr3a1; Ers1), and glucocorticoid receptor (Nr3c1; Gr) expression were observed. Furthermore, significant demethylation in regulatory regions of Mr, Gr, and Esr1 was observed in the PND50 kidney derived from fathers exposed to sGC. This is the first demonstration that paternal pharmacological exposure to sGC can alter the expression and DNA methylation of nuclear steroid receptors in brain and somatic tissues of offspring. These findings provide proof of principle that adult male exposure to sGC can affect DNA methylation and gene expression in offspring, indicating the possibility that adult experiences that evoke increases in endogenous glucocorticoid (i.e., stress) might have similar effects.

  19. Targeted genome-wide methylation and gene expression analyses reveal signaling pathways involved in ovarian dysfunction after developmental EDC exposure in rats.

    PubMed

    Zama, Aparna Mahakali; Uzumcu, Mehmet

    2013-02-01

    Transient exposure to methoxychlor (MXC), an environmental endocrine-disrupting chemical, during fetal and neonatal stages causes ovarian dysfunction in pubertal, adult, and aging animals. Adult animals have reduced number of ovulations and abnormal follicular composition associated with altered gene expression and DNA methylation patterns. To test the hypothesis that the ovarian epigenomic changes induced by MXC are detectable following the exposure period, leading to altered gene expression by adulthood, we conducted a targeted genome-wide methylation study using Nimblegen 3x720K CpG Island Plus RefSeq Promoter Arrays. Control (vehicle), low-dose MXC (20 μg/kg/day), or high-dose MXC (100 mg/kg/day) treatments were administered between Embryonic Day 19 and Postnatal Day (PND) 7. Ovaries were collected at PND 7 immediately after exposure or at adulthood, PND 60. Array hybridizations were conducted with genomic DNA after methylated DNA immunoprecipitation and the array data were analyzed. DNA methylation events were functionally annotated, and candidate loci common to all the treatments or unique to some treatments were identified. Specific loci encoding signaling molecules such as the regulatory subunit p85 of phosphoinositide-3-kinase, insulin-like growth factor-1 receptor, Harvey rat sarcoma viral oncogene, insulin receptor, and forkhead box protein O3 were identified to be hypermethylated in MXC-treated ovaries at PND 7 and/or PND 60. Examination of gene expression changes with TaqMan low-density arrays revealed that nearly 25% of the genes that were assayed were downregulated. These data demonstrate that key molecules in specific signaling pathways such as PTEN signaling, IGF-1 signaling, or rapid estrogen signaling are epigenetically altered in MXC-exposed ovaries, which is associated with ovarian dysfunction and female infertility.

  20. Community exposures to airborne agricultural pesticides in California: ranking of inhalation risks.

    PubMed

    Lee, Sharon; McLaughlin, Robert; Harnly, Martha; Gunier, Robert; Kreutzer, Richard

    2002-12-01

    We assessed inhalation risks to California communities from airborne agricultural pesticides by probability distribution analysis using ambient air data provided by the California Air Resources Board and the California Department of Pesticide Regulation. The pesticides evaluated include chloropicrin, chlorothalonil, chlorpyrifos, S,S,S-tributyl phosphorotrithioate, diazinon, 1,3-dichloropropene, dichlorvos (naled breakdown product), endosulfan, eptam, methidathion, methyl bromide, methyl isothiocyanate (MITC; metam sodium breakdown product), molinate, propargite, and simazine. Risks were estimated for the median and 75th and 95th percentiles of probability (50, 25, and 5% of the exposed populations). Exposure estimates greater than or equal to noncancer reference values occurred for 50% of the exposed populations (adults and children) for MITC subchronic and chronic exposures, methyl bromide subchronic exposures (year 2000 monitoring), and 1,3-dichloropropene subchronic exposures (1990 monitoring). Short-term chlorpyrifos exposure estimates exceeded the acute reference value for 50% of children (not adults) in the exposed population. Noncancer risks were uniformly higher for children due to a proportionately greater inhalation rate-to-body weight ratio compared to adults and other factors. Target health effects of potential concern for these exposures include neurologic effects (methyl bromide and chlorpyrifos) and respiratory effects (1,3-dichloropropene and MITC). The lowest noncancer risks occurred for simazine and chlorothalonil. Lifetime cancer risks of one-in-a-million or greater were estimated for 50% of the exposed population for 1,3-dichloropropene (1990 monitoring) and 25% of the exposed populations for methidathion and molinate. Pesticide vapor pressure was found to be a better predictor of inhalation risk compared to other methods of ranking pesticides as potential toxic air contaminants. PMID:12460795

  1. Community exposures to airborne agricultural pesticides in California: ranking of inhalation risks.

    PubMed Central

    Lee, Sharon; McLaughlin, Robert; Harnly, Martha; Gunier, Robert; Kreutzer, Richard

    2002-01-01

    We assessed inhalation risks to California communities from airborne agricultural pesticides by probability distribution analysis using ambient air data provided by the California Air Resources Board and the California Department of Pesticide Regulation. The pesticides evaluated include chloropicrin, chlorothalonil, chlorpyrifos, S,S,S-tributyl phosphorotrithioate, diazinon, 1,3-dichloropropene, dichlorvos (naled breakdown product), endosulfan, eptam, methidathion, methyl bromide, methyl isothiocyanate (MITC; metam sodium breakdown product), molinate, propargite, and simazine. Risks were estimated for the median and 75th and 95th percentiles of probability (50, 25, and 5% of the exposed populations). Exposure estimates greater than or equal to noncancer reference values occurred for 50% of the exposed populations (adults and children) for MITC subchronic and chronic exposures, methyl bromide subchronic exposures (year 2000 monitoring), and 1,3-dichloropropene subchronic exposures (1990 monitoring). Short-term chlorpyrifos exposure estimates exceeded the acute reference value for 50% of children (not adults) in the exposed population. Noncancer risks were uniformly higher for children due to a proportionately greater inhalation rate-to-body weight ratio compared to adults and other factors. Target health effects of potential concern for these exposures include neurologic effects (methyl bromide and chlorpyrifos) and respiratory effects (1,3-dichloropropene and MITC). The lowest noncancer risks occurred for simazine and chlorothalonil. Lifetime cancer risks of one-in-a-million or greater were estimated for 50% of the exposed population for 1,3-dichloropropene (1990 monitoring) and 25% of the exposed populations for methidathion and molinate. Pesticide vapor pressure was found to be a better predictor of inhalation risk compared to other methods of ranking pesticides as potential toxic air contaminants. PMID:12460795

  2. Exposure of JB-6 mouse epidermal cells to 12-O-tetradecanoyl-phorbol-13-acetate is not accompanied by a significant change in total DNA-cytosine methylation.

    PubMed

    Bondy, G P; Denhardt, D T

    1983-12-01

    The extent of methylation of the cytosine bases in DNA is believed to be a major factor influencing gene expression in eukaryotic cells. We have asked whether the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) alters the amount of 5-methylcytosine in DNA. The amount and relative distribution of 5-methylcytosine in the DNA of two subclones of the JB-6 mouse epidermal cell line were determined respectively by high performance liquid chromatography and digestion with the restriction enzymes MspI and HpaII. Exposure to TPA for up to several cell generations had no detectable effect on the degree of DNA methylation (3.9% of the total cytosine) in the two JB-6 lines or Friend erythroleukemia cells. Reduced methylation was readily detected in DNA extracted from cells exposed to 5-azacytidine. The data suggest that tumor promotion (at least that induced by TPA) is likely not the consequence of a generalized elevation or reduction in the amount of 5-methyl-cytosine in the DNA.

  3. Caffeine-induced fetal rat over-exposure to maternal glucocorticoid and histone methylation of liver IGF-1 might cause skeletal growth retardation.

    PubMed

    Tan, Yang; Liu, Jin; Deng, Yu; Cao, Hong; Xu, Dan; Cu, Fenglong; Lei, Youying; Magdalou, Jacques; Wu, Min; Chen, Liaobin; Wang, Hui

    2012-11-15

    Several epidemiological investigations, including previous work by our laboratory, indicate that maternal caffeine consumption is associated with intrauterine growth retardation and impaired fetal length growth. Skeletal development is critical for length growth. In the present study, our goals were to determine the effects of prenatal caffeine exposures on fetal skeletal growth and to investigate the mechanisms associated with such effects. Pregnant Wistar rats were injected intragastrically with 120mg/kg of caffeine intragastrically each day from gestational days 11-20. Maternal prenatal caffeine exposure was associated with decreased fetal femur lengths and inhibited of synthesis of extracellular matrices in fetal growth plates Moreover, caffeine exposure significantly increased the levels of fetal blood corticosterone and decreased IGF-1mRNA expression levels in the liver and growth plate. The expression levels of IGF-1 signaling pathway components (IGF-1R, IRS-1, AKT1/2 and Col2A1) were also reduced. In addition, the results of chromatin immunoprecipitation assays indicated that caffeine exposure down-regulated histone methylation of fetal IGF-1 in the liver. These results suggest that prenatal caffeine exposure may inhibit fetal skeletal growth through a mechanism that is associated with increased fetal exposure to maternal glucocorticoids and results in lower IGF-1 signaling pathway activity. Taken together, these results raise important concerns regarding the skeletal growth toxicity of caffeine and potentially indicate the intrauterine origins of adult osteoporosis and osteoarthritis.

  4. Enhanced GSH synthesis by Bisphenol A exposure promoted DNA methylation process in the testes of adult rare minnow Gobiocypris rarus.

    PubMed

    Yuan, Cong; Zhang, Yingying; Liu, Yan; Zhang, Ting; Wang, Zaizhao

    2016-09-01

    DNA methylation is a commonly studied epigenetic modification. The mechanism of BPA on DNA methylation is poorly understood. The present study aims to explore whether GSH synthesis affects DNA methylation in the testes of adult male rare minnow Gobiocypris rarus in response to Bisphenol A (BPA). Male G. rarus was exposed to 1, 15 and 225μgL(-1) BPA for 7 days. The levels of global DNA methylation, hydrogen peroxide (H2O2) and glutathione (GSH) in the testes were analyzed. Meanwhile, the levels of enzymes involved in DNA methylation and de novo GSH synthesis, and the substrate contents for GSH production were measured. Furthermore, gene expression profiles of the corresponding genes of all studied enzymes were analyzed. Results indicated that BPA at 15 and 225μgL(-1) caused hypermethylation of global DNA in the testes. The 15μgL(-1) BPA resulted in significant decrease of ten-eleven translocation proteins (TETs) while 225μgL(-1) BPA caused significant increase of DNA methyltransferase proteins (DNMTs). Moreover, 225μgL(-1) BPA caused significant increase of H2O2 and GSH levels, and the de novo GSH synthesis was enhanced. These results indicated that the significant decrease of the level of TETs may be sufficient to cause the DNA hypermethylation by 15μgL(-1) BPA. However, the significantly increased of DNMTs contributed to the significant increase of DNA methylation levels by 225μgL(-1) BPA. Moreover, the elevated de novo GSH synthesis may promote the DNA methylation process. PMID:27474941

  5. Toxicity of methyl tertiary-butyl ether (MTBE) following exposure of Wistar Rats for 13 weeks or one year via drinking water.

    PubMed

    Bermudez, Edilberto; Willson, Gabrielle; Parkinson, Horace; Dodd, Darol

    2012-09-01

    Thirteen-week and one-year toxicity studies of methyl tertiary-butyl ether (MTBE) administered in drinking water to Wistar rats were conducted. Male and female rats were exposed to MTBE in drinking water at 0.5, 3, 7.5 and 15 mg ml(-1) for 13 weeks and at 0.5, 3 and 7.5 (males) or 0.5, 3 and 15 mg ml(-1) (females) for 1 year. Body weights were reduced only in males following 13 weeks of exposure. Reduced water consumption and urine output were observed in males and females exposed to MTBE. Kidney cell replication and α(2u)-globulin levels in males were increased at 1 and 4 weeks of MTBE exposure and tubular cell regeneration was increased in male kidneys exposed to MTBE concentrations of 7.5 mg ml(-1) or greater for 13 weeks. Wet weights of male kidneys were increased following 13 weeks, 6 months and 1 year of exposure to MTBE concentrations of 7.5 mg ml(-1) or greater. Kidney wet weights were increased in females at MTBE concentrations of 15 mg ml(-1) for 13 weeks. Tertiary-butyl alcohol blood levels increased linearly with dose in males and females following 1 year of exposure. Chronic progressive nephropathy (CPN), of minimal to mild severity, increased in males, but not females, with 1 year of MTBE exposure. In summary, exposure of Wistar rats to MTBE in the drinking water resulted in minimal exposure-related effects including limited renal changes in male rats suggestive of α(2u)-globulin nephropathy following 13 weeks of exposure and an exacerbation of CPN in males at the end of 1 year of exposure. PMID:22833177

  6. Toxicity of methyl tertiary-butyl ether (MTBE) following exposure of Wistar Rats for 13 weeks or one year via drinking water.

    PubMed

    Bermudez, Edilberto; Willson, Gabrielle; Parkinson, Horace; Dodd, Darol

    2012-09-01

    Thirteen-week and one-year toxicity studies of methyl tertiary-butyl ether (MTBE) administered in drinking water to Wistar rats were conducted. Male and female rats were exposed to MTBE in drinking water at 0.5, 3, 7.5 and 15 mg ml(-1) for 13 weeks and at 0.5, 3 and 7.5 (males) or 0.5, 3 and 15 mg ml(-1) (females) for 1 year. Body weights were reduced only in males following 13 weeks of exposure. Reduced water consumption and urine output were observed in males and females exposed to MTBE. Kidney cell replication and α(2u)-globulin levels in males were increased at 1 and 4 weeks of MTBE exposure and tubular cell regeneration was increased in male kidneys exposed to MTBE concentrations of 7.5 mg ml(-1) or greater for 13 weeks. Wet weights of male kidneys were increased following 13 weeks, 6 months and 1 year of exposure to MTBE concentrations of 7.5 mg ml(-1) or greater. Kidney wet weights were increased in females at MTBE concentrations of 15 mg ml(-1) for 13 weeks. Tertiary-butyl alcohol blood levels increased linearly with dose in males and females following 1 year of exposure. Chronic progressive nephropathy (CPN), of minimal to mild severity, increased in males, but not females, with 1 year of MTBE exposure. In summary, exposure of Wistar rats to MTBE in the drinking water resulted in minimal exposure-related effects including limited renal changes in male rats suggestive of α(2u)-globulin nephropathy following 13 weeks of exposure and an exacerbation of CPN in males at the end of 1 year of exposure.

  7. Epigenome-wide DNA methylation analysis implicates neuronal and inflammatory signaling pathways in adult murine hepatic tumorigenesis following perinatal exposure to bisphenol A.

    PubMed

    Weinhouse, Caren; Sartor, Maureen A; Faulk, Christopher; Anderson, Olivia S; Sant, Karilyn E; Harris, Craig; Dolinoy, Dana C

    2016-07-01

    Developmental exposure to the endocrine-active compound bisphenol A (BPA) has been linked to epigenotoxic and potential carcinogenic effects in rodent liver, prostate, and mammary glands. A dose-dependent increase in hepatic tumors in 10-month mice perinatally exposed to one of three doses of BPA (50 ng, 50 µg, or 50 mg BPA/kg chow) was previously reported. These tumors represent early-onset disease and lack classical sexual dimorphism in incidence. Here, adult epigenome-wide liver DNA methylation profiles to identify gene promoters associated with perinatal BPA exposure and disease in 10-month mice with and without liver tumors were investigated. Mice with hepatic tumors showed 12,822 (1.8%) probes with differential methylation as compared with non-tumor animals, of which 8,656 (67.5%) were hypomethylated. A significant enrichment of differential methylation in Gene Ontology (GO) terms and biological processes related to morphogenesis and development, and epigenomic alteration were observed. Pathway enrichment revealed a predominance of hypermethylated neuronal signaling pathways linked to energy regulation and metabolic function, supporting metabolic consequences in the liver via BPA-induced disruption of neuronal signaling pathways. Hypothesis-driven pathway analysis revealed mouse and human genes linked to BPA exposure related to intracellular Jak/STAT and MAPK signaling pathways. Taken together, these findings are indicators of the relevance of the hepatic tumor phenotype seen in BPA-exposed mice to human health. This work demonstrated that epigenome-wide discovery experiments in animal models were effective tools for identification and understanding of paralagous epimutations salient to human disease. Environ. Mol. Mutagen. 57:435-446, 2016. © 2016 Wiley Periodicals, Inc. PMID:27334623

  8. Assessment of genotoxicity in gonads, liver and gills of zebrafish (Danio rerio) by use of the comet assay and micronucleus test after in vivo exposure to methyl methanesulfonate.

    PubMed

    Faßbender, Christopher; Braunbeck, Thomas

    2013-07-01

    Since generative tissues are a link between the generations, the detection of genetic damage in testis and ovary of fish is conductive to elucidating the relationship between genotoxicity and impairment of reproduction. In the current study, exposure of zebrafish to methyl methanesulfonate over two weeks caused concentration dependent genotoxic effects in gonads, liver and gills using the alkaline comet assay. Likewise, the micronucleus frequency was elevated in all of these organs. Thus, the comet assay and the micronucleus test proved appropriate for the detection of genotoxicity in primary male and female gonad cells and histological sections of the gonads from zebrafish, respectively.

  9. Pacific area wide program for methyl bromide alternatives – Ornamentals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During the past 5 years the following field trials have been conducted as part of the Pacific Area-Wide program for cut flowers and ornamentals using various combinations of 1, 3-dichloropropene, chloropicrin, and metam: 1) Drip demonstration trial with field-grown calla lilies at Golden State Bulb ...

  10. Reaction kinetics of the CN radical with methyl bromide

    NASA Astrophysics Data System (ADS)

    Hodny, Michael; Hershberger, John F.

    2016-02-01

    The kinetics of the CN + CH3Br reaction were studied using transient infrared laser absorption spectroscopy to detect CN reactants and HCN products. This reaction has a rate constant of k = (2.20 ± 0.6) × 10-12 exp (453 ± 98/T) cm3 molecule-1 s-1 over the range 298-523 K. Hydrogen abstraction to produce HCN + CH2Br is only a minor reaction product, with a branching fraction of 0.12 ± 0.02. Other product channels, including BrCN + CH3, CH2CN + HBr, CH3CN + Br are likely. An upper limit of 0.01 was established for the HBr yield. These results are in qualitative agreement with recent ab initio calculations.

  11. Atmospheric methyl bromide - Trends and global mass balance

    NASA Technical Reports Server (NTRS)

    Khalil, M. A. K.; Rasmussen, R. A.; Gunawardena, R.

    1993-01-01

    A decadal time series of global CH3Br concentrations in the earth's atmosphere is presented. It is shown that average concentrations are about 10 pptv and during the last 4 yr may be increasing at 0.3 +/- 0.1 pptv/yr. It is estimated that the atmospheric lifetime of CH3Br that is due to reaction with OH is about 2 yr, which results in a calculated global emission rate of about 100 Gg/yr. Ocean supersaturations of 140-180 percent are observed, and atmospheric concentrations over the open oceans are higher than at comparably located coastal sites. The ocean source is estimated to be about 35 Gg/yr. The remaining emissions must come from other natural sources and anthropogenic activities.

  12. 77 FR 20752 - Methyl Bromide; Proposed Pesticide Tolerance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-06

    ... Review'' (58 FR 51735, October 4, 1993). Because this proposed rule has been exempted from review under..., or Use'' (66 FR 28355, May 22, 2001). This proposed rule does not contain any information collections...-Income Populations'' (59 FR 7629, February 16, 1994); or OMB review or any Agency action under...

  13. Environmental fate of methyl bromide as a soil fumigant.

    PubMed

    Yates, Scott R; Gan, Jay; Papiernik, Sharon K

    2003-01-01

    The great variation among results of recent experiments measuring the total emission of MeBr from fields implies that many factors influence MeBr transport and transformation in the soil-water-air system and its ultimate loss from the soil surface. It has been demonstrated that variables related to application methods (e.g., injection depth, use and type of surface tarp), soil properties (e.g., water content, bulk density, soil organic matter), and climatic conditions (e.g.. air temperature, wind speed, barometric pressure) have pronounced effects on MeBr volatilization following soil injection. The following conclusions can be drawn from this experimental information. Tarping consistently, increased the residence time and concentration of MeBr residing in the soil. Prolonged retention of MeBr in the soil resulted in more extensive degradation and reduced cumulative emissions. Research indicates that the polyethylene film typically used for the surface cover is relatively permeable to MeBr and allows significant emissions compared to virtually impermeable plastic films. This effect is more pronounced during periods of high temperature. Soil type, soil water content, and bulk density are important factors affecting MeBr transport and transformation in soil, which ultimately affect volatilization. The total volatilization from a soil with high organic matter content may be drastically reduced relative to that from a low organic matter soil. Amendment of the surface soil with organic matter or nucleophilic compounds that promote increased degradation may offer another method for reducing volatilization. MeBr volatilization may also be decreased by increasing soil water content and bulk density, mainly because of the reduced gas-phase diffusion resulting from reduced soil air-filled porosity. To minimize volatilization, MeBr should be applied during periods of cool temperature, injected relatively deep in organic-rich, moist soil, and the soil surface packed and tarped immediately after the application. Depending on site-specific conditions, a new high-barrier plastic should be used. Injecting MeBr during periods of warm temperature, at a shallow depth in dry, loose soil without the use of low-permeability plastic barriers, will likely result in maximum volatilization rates and therefore should be discouraged. Before adopting any new emission reduction technology, the pest control characteristics of the new methodology should be assessed under soil and environmental conditions typical of the region to optimize efficacy while minimizing environmental contamination. There is considerable current scientific evidence indicating that eliminating MeBr use for soil fumigation may not have a significant impact on stratospheric ozone depletion. Management practices can and have been developed that essentially eliminate atmospheric emissions of MeBr and other fumigant compounds following soil application. Some scientists have suggested that there are natural buffers and various unknown sources of MeBr that make it impossible to ascertain that eliminating soil fumigation with MeBr will significantly improve stratospheric ozone levels. It is quite certain, however, that the phase-out will make it much more difficult for growers to economically provide an adequate and healthful food supply in the U.S. and elsewhere in the world. As the phase-out date approaches, there remains a great need for information about MeBr and stratospheric ozone depletion. Stratospheric ozone must be protected, but recent experiments suggest that it can be protected while still allowing MeBr to be used for soil fumigation. A new approach may be warranted in which state and federal regulations recognize that every chemical is a potential environmental contaminant, depending on the properties of the chemical and the environmental conditions prevailing following its application. Ideally, regulations should incorporate incentives to develop technology that minimizes the likelihood that a chemical becomes an environmental and/or public health problem. Rather than instituting an irrevocable ban, allowing for a suspension of chemical use until the appropriate technology is developed to control the undesirable characteristic(s) of the chemical use would provide much more flexibility to growers and may enhance environmental protection by adopting a proactive approach in which growers, chemical manufacturers, regulators, and the public can have confidence. PMID:12666818

  14. 75 FR 5582 - Methyl Bromide; Amendments to Terminate Uses

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-03

    ..., human health, and agricultural advocates; the chemical industry; pesticide users; and members of the... Amended Products EPA Company Number Company Name and Address 5785 Great Lakes Chemical Corporation P.O. Box 2200 West Lafayette, IN 47996- 2200 8536 Soil Chemicals Corporation (doing business as...

  15. Environmental fate of methyl bromide as a soil fumigant.

    PubMed

    Yates, Scott R; Gan, Jay; Papiernik, Sharon K

    2003-01-01

    The great variation among results of recent experiments measuring the total emission of MeBr from fields implies that many factors influence MeBr transport and transformation in the soil-water-air system and its ultimate loss from the soil surface. It has been demonstrated that variables related to application methods (e.g., injection depth, use and type of surface tarp), soil properties (e.g., water content, bulk density, soil organic matter), and climatic conditions (e.g.. air temperature, wind speed, barometric pressure) have pronounced effects on MeBr volatilization following soil injection. The following conclusions can be drawn from this experimental information. Tarping consistently, increased the residence time and concentration of MeBr residing in the soil. Prolonged retention of MeBr in the soil resulted in more extensive degradation and reduced cumulative emissions. Research indicates that the polyethylene film typically used for the surface cover is relatively permeable to MeBr and allows significant emissions compared to virtually impermeable plastic films. This effect is more pronounced during periods of high temperature. Soil type, soil water content, and bulk density are important factors affecting MeBr transport and transformation in soil, which ultimately affect volatilization. The total volatilization from a soil with high organic matter content may be drastically reduced relative to that from a low organic matter soil. Amendment of the surface soil with organic matter or nucleophilic compounds that promote increased degradation may offer another method for reducing volatilization. MeBr volatilization may also be decreased by increasing soil water content and bulk density, mainly because of the reduced gas-phase diffusion resulting from reduced soil air-filled porosity. To minimize volatilization, MeBr should be applied during periods of cool temperature, injected relatively deep in organic-rich, moist soil, and the soil surface packed and tarped immediately after the application. Depending on site-specific conditions, a new high-barrier plastic should be used. Injecting MeBr during periods of warm temperature, at a shallow depth in dry, loose soil without the use of low-permeability plastic barriers, will likely result in maximum volatilization rates and therefore should be discouraged. Before adopting any new emission reduction technology, the pest control characteristics of the new methodology should be assessed under soil and environmental conditions typical of the region to optimize efficacy while minimizing environmental contamination. There is considerable current scientific evidence indicating that eliminating MeBr use for soil fumigation may not have a significant impact on stratospheric ozone depletion. Management practices can and have been developed that essentially eliminate atmospheric emissions of MeBr and other fumigant compounds following soil application. Some scientists have suggested that there are natural buffers and various unknown sources of MeBr that make it impossible to ascertain that eliminating soil fumigation with MeBr will significantly improve stratospheric ozone levels. It is quite certain, however, that the phase-out will make it much more difficult for growers to economically provide an adequate and healthful food supply in the U.S. and elsewhere in the world. As the phase-out date approaches, there remains a great need for information about MeBr and stratospheric ozone depletion. Stratospheric ozone must be protected, but recent experiments suggest that it can be protected while still allowing MeBr to be used for soil fumigation. A new approach may be warranted in which state and federal regulations recognize that every chemical is a potential environmental contaminant, depending on the properties of the chemical and the environmental conditions prevailing following its application. Ideally, regulations should incorporate incentives to develop technology that minimizes the likelihood that a chemical becomes an environmental and/or public health problem. Rather than in

  16. Combined toxicities of methyl tert-butyl ether and its metabolite tert-butyl alcohol on earthworms via different exposure routes.

    PubMed

    Lee, Woo-Mi; Yoon, Youngdae; An, Youn-Joo

    2015-06-01

    Methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) are among the major soil contaminants that threaten the health of soil ecosystems. Many MTBE-contaminated sites accumulate TBA, because TBA is the intermediate of MTBE biodegradation. To access the risk of MTBE and TBA in soil, we investigated the combined toxicities of MTBE and TBA using two earthworm species, Perionyx excavatus and Eisenia andrei, as well as the toxic effects via different exposure routes. The combined toxicity showed weak antagonistic effects (LC50mix values were slightly greater than 1.0), and sensitivity toward same pollutants differed in the two earthworm species. Moreover, the toxicity of MTBE and TBA was also affected by the exposure route; both filter paper and artificial soil tests showed that dermal-only exposure to MTBE had an even greater toxic effect than combined dermal and oral exposure. Thus, we suggest that diverse environmental factors including organic materials, the physicochemical properties of the contact media, and the exposure routes of the organism, should be taken into consideration when assessing the effects of pollutants on organisms in diverse environmental systems.

  17. Lanthanum Bromide Detectors for Safeguards Measurements

    SciTech Connect

    Wright, J.

    2011-05-25

    Lanthanum bromide has advantages over other popular inorganic scintillator detectors. Lanthanum bromide offers superior resolution, and good efficiency when compared to sodium iodide and lanthanum chloride. It is a good alternative to high purity germanium detectors for some safeguards applications. This paper offers an initial look at lanthanum bromide detectors. Resolution of lanthanum bromide will be compared lanthanum chloride and sodium-iodide detectors through check source measurements. Relative efficiency and angular dependence will be looked at. Nuclear material spectra, to include plutonium and highly enriched uranium, will be compared between detector types.

  18. DERMAL EXPOSURE TO METHYL TERT-BUTYL ETHER (MTBE) AND DIBROMOCHLOROMETHANE (DBCM) WHILE BATHING WITH CONTAMINATED WATER

    EPA Science Inventory

    The oxygenate methyl tert-butyl ether (MTBE) has been added to gasoline to help meet national ambient air quality standards in those parts of the U.S. that are non-compliant for carbon monoxide. Although MTBE has provided important health benefits in terms of reduced hazardous a...

  19. Effects of lead exposure on GnRH and LH secretion in male rats: response to castration and alpha-methyl-p-tyrosine (AMPT) challenge.

    PubMed

    Sokol, R Z; Berman, N; Okuda, H; Raum, W

    1998-01-01

    Animal and clinical studies suggest that lead exposure disrupts the hypothalamic-pituitary axis. To define more precisely the toxic action of lead on the hypothalamic-pituitary unit, a series of in vivo and in vitro experiments were performed. The first experiment was designed to determine whether lead exposure exerts an inhibitory effect on GnRH secretion as reflected by an enhanced inhibition of luteinizing hormone (LH) secretion in response to the tyrosine hydroxylase inhibitor methyl-p-tyrosine (AMPT). In the control animals, the AMPT dose had no significant effect on LH secretion, whereas LH fell significantly in the lead-treated animals. In experiments designed to evaluate the effects of lead exposure on the pattern of pulsatile release of gonadotropins castrated control and lead-dosed animals were cannulated, and serial blood sampling was performed. Baseline LH and follicle-stimulating hormone values were not statistically different between the control and lead-treated group. There were no significant differences noted in pulsatile patterns when the data were analyzed as groups. Pituitary cells harvested from lead-treated animals released significantly more LH that did the control animals. These data are consistent with the hypothesis that the signals between the hypothalamus and pituitary gland are disrupted by lead exposure in the intact animal. However, the lead-exposed castrated rat's hypothalamic-pituitary unit is able to adapt to the toxic effects of lead.

  20. 77 FR 29218 - Protection of Stratospheric Ozone: The 2012 Critical Use Exemption From the Phaseout of Methyl...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-17

    ... was originally published in the Federal Register on August 12, 1988 (53 FR 30566), in response to the... (58 FR 65018), listing methyl bromide as a Class I, Group VI controlled substance, freezing U.S... November 28, 2000 (65 FR 70795), which allowed for the phased reduction in methyl bromide...

  1. 75 FR 23167 - Protection of Stratospheric Ozone: The 2010 Critical Use Exemption From the Phaseout of Methyl...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-03

    ... on August 12, 1988 (53 FR 30566), in response to the 1987 signing and subsequent ratification of the... in the Federal Register on December 10, 1993 (58 FR 65018), listing methyl bromide as a Class I... (65 FR 70795), which allowed for the phased reduction in methyl bromide consumption specified...

  2. 77 FR 74435 - Protection of Stratospheric Ozone: The 2013 Critical Use Exemption From the Phaseout of Methyl...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-14

    ... A. The regulatory program was originally published in the Federal Register on August 12, 1988 (53 FR... December 10, 1993 (58 FR 65018), listing methyl bromide as a Class I, Group VI controlled substance. This... on November 28, 2000 (65 FR 70795), which allowed for the reduction in methyl bromide...

  3. 76 FR 23769 - Protection of Stratospheric Ozone: The 2011 Critical Use Exemption From the Phaseout of Methyl...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-28

    ... August 12, 1988 (53 FR 30566), in response to the 1987 signing and subsequent ratification of the... in the Federal Register on December 10, 1993 (58 FR 65018), listing methyl bromide as a Class I... (65 FR 70795), which allowed for the phased reduction in methyl bromide consumption specified...

  4. Dangerous and cancer-causing properties of products and chemicals in the oil-refining and petrochemical industry--Part XXII: Health hazards from exposure to gasoline containing methyl tertiary butyl ether: study of New Jersey residents.

    PubMed

    Mehlman, M A

    1996-01-01

    Methyl tertiary butyl ether has caused the following cancers in rats and mice: kidney, testicular, liver, lymphomas, and leukemias. Thus, in the absence of adequate data on humans, it is biologically plausible and prudent to regard methyl tertiary butyl ether-for which there is sufficient evidence of carcinogenicity in experimental animals-as a probable human carcinogen. This means that some humans are at extreme risk of contracting cancers resulting from their exposure to oxygenated gasoline containing methyl tertiary butyl ether. Immediately after the introduction of methyl tertiary butyl ether into gasoline, many consumers of this product in New Jersey, New York, Alaska, Maine, Pennsylvania, Colorado, Arizona, Montana, Massachusetts, California, and other areas, experienced a variety of neurotoxic, allergic, and respiratory illnesses. These illnesses were similar to those suffered by refinery workers from the Oil, Chemical, and Atomic Workers Union who mixed methyl tertiary butyl ether with gasoline. Additionally, these illnesses occurred following exposure to extremely low levels of methyl tertiary butyl ether in gasoline, particularly when compared to the adverse health effects that occurred only after exposure to very high levels of conventional gasoline. Thus, gasoline containing methyl tertiary butyl ether exhibited substantially more toxicity in humans than gasoline without this additive. A number of oil industry-sponsored or influenced reports alleged that these illnesses were either unrelated to exposure to reformulated gasoline or were characteristic of some yet-to-be-identified communicable disease. These studies further alleged that the widespread concern was not about illness, but was merely a reaction to the odor and the five cent increase in the price of gasoline. To clarify the significance of this issue, it is important to note that consumers have been using gasoline for many decades, with complaints only occurring following exposure to high

  5. Long-term arsenic exposure induces histone H3 Lys9 dimethylation without altering DNA methylation in the promoter region of p16(INK4a) and down-regulates its expression in the liver of mice.

    PubMed

    Suzuki, Takehiro; Nohara, Keiko

    2013-09-01

    Long-term exposure of humans to high concentrations of arsenic is associated with an increased risk of cancer. Previous studies have suggested that arsenic exposure promotes tumorigenesis by inducing changes in the expression of tumor-related genes by dysregulating DNA methylation at tumor-related gene loci. However, the causal relationships between epigenetic changes and both arsenic exposure and tumorigenesis are still unclear. In the present study, we investigated whether arsenic can change the expression of tumor-related genes by inducing epigenetic modifications before tumorigenesis. We did so by investigating the effects of long-term arsenic exposure on representative epigenetic modifications, DNA methylation and histone modifications, in the tumor-free normal liver of C57Bl/6 mice. We focused on the tumor-related genes, p16(INK4a) , RASSF1A, Ha-ras and ER-α as target genes, because their expression and promoter methylation status in mice have been reported to be affected by long-term arsenic exposure. The results showed that long-term arsenic exposure induced a significant decrease in expression of p16(INK4a) associated with an increase in level of dimethylated histone H3 lysine 9 (H3K9), a transcription-suppressive histone modification, in the promoter region, but that DNA methylation of the promoter region was unaffected. The results also showed a significant increase in recruitment of H3K9 histone methyltransferase G9a to the promoter after arsenic exposure. These findings suggest that long-term arsenic exposure may induce down-regulation of p16(INK4a) by targeting recruitment of G9a and H3K9 dimethylation without altering DNA methylation before tumorigenesis in the liver.

  6. Paternal heat exposure causes DNA methylation and gene expression changes of Stat3 in Wild guinea pig sons.

    PubMed

    Weyrich, Alexandra; Benz, Stephanie; Karl, Stephan; Jeschek, Marie; Jewgenow, Katarina; Fickel, Joerns

    2016-05-01

    Epigenetic mechanisms convey environmental information through generations and can regulate gene expression. Epigenetic studies in wild mammals are rare, but enable understanding adaptation processes as they may occur in nature. In most wild mammal species, males are the dispersing sex and thus often have to cope with differing habitats and thermal changes more rapidly than the often philopatric females. As temperature is a major environmental selection factor, we investigated whether genetically heterogeneous Wild guinea pig (Cavia aperea) males adapt epigenetically to an increase in temperature, whether that response will be transmitted to the next generation(s), and whether it regulates mRNA expression. Five (F0) adult male guinea pigs were exposed to an increased ambient temperature for 2 months, corresponding to the duration of the species' spermatogenesis. To study the effect of heat, we focused on the main thermoregulatory organ, the liver. We analyzed CpG-methylation changes of male offspring (F1) sired before and after the fathers' heat treatment (as has recently been described in Weyrich et al. [Mol. Ecol., 2015]). Transcription analysis was performed for the three genes with the highest number of differentially methylated changes detected: the thermoregulation gene Signal Transducer and Activator of Transcription 3 (Stat3), the proteolytic peptidase gene Cathepsin Z (Ctsz), and Sirtuin 6 (Sirt6) with function in epigenetic regulation. Stat3 gene expression was significantly reduced (P < 0.05), which indicated a close link between CpG-methylation and expression levels for this gene. The two other genes did not show gene expression changes. Our results indicate the presence of a paternal transgenerational epigenetic effect. Quick adaptation to climatic changes may become increasingly relevant for the survival of wildlife species as global temperatures are rising. PMID:27066228

  7. Exposure to difenoconazole, diclofop-methyl alone and combination alters oxidative stress and biochemical parameters in albino rats.

    PubMed

    Abd-Alrahman, Sherif H; Elhalwagy, Manal Ea; Kotb, Gamila Ahmed; Farid, Hoda; Farag, Ahmed Ag; Draz, Hossam M; Isa, Ahmed M; Sabico, S

    2014-01-01

    The herbicides diclofop-methyl and the fungicide difenoconazole are widely used in agriculture and may lead to serious toxicity risks. However, limited studies have been done to evaluate differences in the metabolic effects of these herbicides. Difenoconazole (10 mg/kg) and Diclofop-methyl (1 mg/kg) were orally administrated individually (Groups 1 and 2 respectively) as well as combined (G3) to rats for 28 days. In all treated groups, alanine aminotransferase (ALT) and urea were significantly higher than the control group. Plasma creatinine was also significantly higher in groups G1 and G2 than control. Significant inhibition in gamma glutamyltransferase (γGT) was observed in all treated groups, in addition to significant inhibition of plasma acetylcholinesterase enzyme (AChE) in G3 (p < 0.01). There was no effect in aspartate aminotransferase (AST) and albumin. Total plasma triiodothy-ronine (T3) hormone was significantly higher in groups G2 and G3 (p < 0.01), but significantly lower in G1 group as compared to control. Thyroxin (T4) was significantly lower in all treated groups than control. Cholesterol level was significantly lower in G3 than control, and a total protein (TP) was significantly higher in all treated groups than control. No differences were observed in glucose levels. Malondialdehyde (MDA) and superoxide dismutase (SOD), an oxidative stress biomarker, was significantly increased in all treated groups comparing to control. Sulphur containing protein (SH-protein) was significantly lower in G1 than control. No significant changes were observed for GST in all treatments. The significant differences in measured biomarkers after application of diclofop-methyl, difenoconazole individually and combined indicate that the investigated pesticides may have potentially harmful effects on humans and the surrounding environment. We suggest that larger studies be conducted to better understand the toxicity mechanisms of these pesticides. PMID:25419412

  8. Uptake of ozone to mixed sodium bromide/ citric acid solutions

    NASA Astrophysics Data System (ADS)

    Lee, Ming-Tao; Steimle, Emilie; Bartels-Rausch, Thorsten; Kato, Shunsuke; Lampimäki, Markus; Brown, Matthew; van Bokhoven, Jeroen; Nolting, Frithjof; Kleibert, Armin; Türler, Andreas; Ammann, Markus

    2013-04-01

    Sea-salt solution - air interfaces play an important role in the chemistry of the marine boundary layer. The reaction of ozone (O3) with bromide is of interest in the context of formation of photolabile halogens (Br2, BrCl) in the marine boundary layer. Recent experiments have suggested that the bromide oxidation rate is related to the surface concentration of bromide [1] and inversely related to the gas phase concentration of O3, an indication for a precursor mediated reaction at the surface [2]. So far, the effect of organics (such as those occurring at the ocean surface or in marine aerosols) on the reaction of O3 with bromide aerosols has not been studied yet. In our study we investigate the uptake kinetics of O3 to a mixed solution of sodium bromide (NaBr) and citric acid (CA), which represents highly oxidized organic compounds present in the environment, with a well-established coated wall flow tube technique, which leads to exposure of the film to O3 allowing the heterogeneous reactions to take place and the loss of O3 being measured. The results indicate that the uptake of O3 to the films with the higher bromide concentrations (0.34M and 4M) is independent of the gas phase concentration and roughly consistent with uptake limited by reaction in the bulk. For the lower bromide concentration (84mM), however, we observe a trend of the uptake coefficient to decrease with increasing O3 concentration, indicating an increasing importance of a surface reaction. In an attempt to constrain the kinetic data, we employed X-ray photoelectron spectroscopy (XPS) to get insight into the surface composition of the aqueous solution - air interface. Previous XPS studies have shown that halide ion concentrations are enhanced at the aqueous solution air interface [3-4], which likely promotes the surface reactions of bromide or iodide with O3. A first XPS study of ternary solutions of KI with butanol indicated the importance of specific interactions of the cation with the alcohol

  9. Potassium bromide method of infrared sampling

    USGS Publications Warehouse

    Milkey, R.G.

    1958-01-01

    In the preparation of potassium bromide pressed windows for use in the infrared analysis of solids, severe grinding of the potassium bromide powder may produce strong absorption bands that could interfere seriously with the spectra of the sample. These absorption bands appear to be due to some crystal alteration of the potassium bromide as a result of the grinding process. They were less apt to occur when the coarser powder, which had received a relatively gentle grinding, was used. Window blanks prepared from the coarser powders showed smaller adsorbed water peaks and generally higher over-all transmittance readings than windows pressed from the very fine powders.

  10. Degradation of Methyl Iodide in Soil: Effects of Environmental Factors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl iodide (MeI) is a promising alternative to the phased-out fumigant methyl bromide, and its environmental fate following soil fumigation is of great concern. Experiments were conducted to investigate the effect of various environmental factors on the degradation rate of MeI in soil. The chem...

  11. DEGRADATION OF METHYL IODIDE IN SOIL: EFFECTS OF ENVIRONMENTAL FACTORS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl iodide (MeI) is a promising alternative to the phased-out fumigant methyl bromide; however, there are concerns about its environmental fate following soil fumigation. Laboratory experiments were conducted to investigate the effect of various environmental factors on the degradation rate of ...

  12. Water and methyl isothiocyanate distribution in soil after drip fumigation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl isothiocyanate (MITC) generators, such as metam sodium (Met-Na), are used for soil fumigation of agricultural land. The ban on the fumigant methyl bromide (MBr) has resulted in greater use of MITC generators. In order to understand the efficacy of MITC, it is necessary to assess its generat...

  13. Carbonation of epoxy methyl soyate at atmospheric pressure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Carbonated methyl soyates were prepared from epoxy methyl soyate by the introduction of carbon dioxide at the oxirane position. Carbonation was performed with carbon dioxide gas by sparging carbon dioxide through the epoxy esters at atmospheric pressure in the presence of tetrabutylammonium bromide...

  14. Bromine and bromide content in soils: Analytical approach from total reflection X-ray fluorescence spectrometry.

    PubMed

    Gallardo, Helena; Queralt, Ignasi; Tapias, Josefina; Candela, Lucila; Margui, Eva

    2016-08-01

    Monitoring total bromine and bromide concentrations in soils is significant in many environmental studies. Thus fast analytical methodologies that entail simple sample preparation and low-cost analyses are desired. In the present work, the possibilities and drawbacks of low-power total reflection X-ray fluorescence spectrometry (TXRF) for the determination of total bromine and bromide contents in soils were evaluated. The direct analysis of a solid suspension using 20 mg of fine ground soil (<63 μm) gave a 3.7 mg kg(-1) limit of detection for bromine which, in most cases, was suitable for monitoring total bromine content in soils (Br content range in soils = 5-40 mg kg(-1)). Information about bromide determination in soils is also possible by analyzing the Br content in water soil extracts. In this case, the TXRF analysis can be directly performed by depositing 10 μL of the internal standardized soil extract sample on a quartz glass reflector in a measuring time of 1500 s. The bromide limit of detection by this approach was 10 μg L(-1). Good agreement was obtained between the TXRF results for the total bromine and bromide determinations in soils and those obtained by other popular analytical techniques, e.g. energy dispersive X-ray fluorescence spectrometry (total bromine) and ionic chromatography (bromide). As a study case, the TXRF method was applied to study bromine accumulation in two agricultural soils fumigated with a methyl bromide pesticide and irrigated with regenerated waste water. PMID:27179429

  15. Bromine and bromide content in soils: Analytical approach from total reflection X-ray fluorescence spectrometry.

    PubMed

    Gallardo, Helena; Queralt, Ignasi; Tapias, Josefina; Candela, Lucila; Margui, Eva

    2016-08-01

    Monitoring total bromine and bromide concentrations in soils is significant in many environmental studies. Thus fast analytical methodologies that entail simple sample preparation and low-cost analyses are desired. In the present work, the possibilities and drawbacks of low-power total reflection X-ray fluorescence spectrometry (TXRF) for the determination of total bromine and bromide contents in soils were evaluated. The direct analysis of a solid suspension using 20 mg of fine ground soil (<63 μm) gave a 3.7 mg kg(-1) limit of detection for bromine which, in most cases, was suitable for monitoring total bromine content in soils (Br content range in soils = 5-40 mg kg(-1)). Information about bromide determination in soils is also possible by analyzing the Br content in water soil extracts. In this case, the TXRF analysis can be directly performed by depositing 10 μL of the internal standardized soil extract sample on a quartz glass reflector in a measuring time of 1500 s. The bromide limit of detection by this approach was 10 μg L(-1). Good agreement was obtained between the TXRF results for the total bromine and bromide determinations in soils and those obtained by other popular analytical techniques, e.g. energy dispersive X-ray fluorescence spectrometry (total bromine) and ionic chromatography (bromide). As a study case, the TXRF method was applied to study bromine accumulation in two agricultural soils fumigated with a methyl bromide pesticide and irrigated with regenerated waste water.

  16. Establishment of reentry intervals for organophosphate-treated cotton fields based on human data: III. 12 To 72 hours post-treatment exposure to monocrotophos, ethyl- and methyl parathion.

    PubMed

    Ware, G W; Morgan, D P; Estesen, B J; Cahill, W P

    1975-01-01

    Five human volunteers entered methyl parathion, ethyl parathion, or monocrotophos treated cotton fields for five-hr exposure periods when the residues of the respective pesticides had aged 12 hr, 24 and 48 hr and 72 hr. Foliage residues of methyl parathion disappeared fastest, those of monocrotophos slowest. Personal exposure to pesticide was evaluated from contamination of skin, clothing, and ambient air, while actual absorption of chemical was assessed from pesticide concentration in blood, urinary metabolite excretion, and effects on blood cholinesterase activities. There was good correspondence between magnitudes of foliar residue, estimates of personal contamination, and measures of chemical absorption. Field exposures caused no symptoms or clinical signs of organophosphate poisoning and depressed averaged blood cholinesterase activities by no more than 14% of pre-exposure levels.

  17. Sex differences in opioid and N-methyl-D-aspartate mediated non-opioid biting fly exposure induced analgesia in deer mice.

    PubMed

    Kavaliers, M; Colwell, D D; Choleris, E

    1998-08-01

    There is evidence for sex differences in responses to noxious stimuli and in the expression and mediation of analgesia. In particular, results of investigations with swim stress and the more ethologically appropriate stress of predator odor exposure have suggested sex differences in N-methyl-D-aspartate (NMDA) receptor system involvement in the mediation of analgesia. Whether or not this sex difference generalizes to other environmental stressors is, however, not clear. Biting flies are a natural aversive stimuli commonly encountered by wild and domestic animals and humans. The present study examined the opioid and non-opioid mediated nociceptive (50 degrees C hot plate) responses of reproductive male and female deer mice, Peromyscus maniculatus, exposed to biting fly attack. A 30 min exposure to biting flies (stable flies, Stomoxys calcitrans (L.)) elicited a naloxone sensitive, opioid-mediated analgesia that was of a greater magnitude in males than in female deer mice. In contrast, a 5 min exposure to biting flies elicited a 'on-opioid' analgesia that was of similar magnitude in both sexes and insensitive to both naloxone and the specific kappa opiate antagonist, nor-binaltorphimine. In male mice this non-opioid analgesia was antagonised by the competitive NMDA antagonist, NPC 1262, while in reproductive females the biting fly-induced analgesia was insensitive to NPC 12626. These results show that there are sex differences in NMDA involvement in the mediation of the non-opioid analgesia arising from brief exposure to the stress of biting fly attack. These data from a common, natural environmental challenge support the presence of basic sex difference in NMDA involvement in the mediation of stress-induced analgesia. PMID:9766834

  18. Sex differences in opioid and N-methyl-D-aspartate mediated non-opioid biting fly exposure induced analgesia in deer mice.

    PubMed

    Kavaliers, M; Colwell, D D; Choleris, E

    1998-08-01

    There is evidence for sex differences in responses to noxious stimuli and in the expression and mediation of analgesia. In particular, results of investigations with swim stress and the more ethologically appropriate stress of predator odor exposure have suggested sex differences in N-methyl-D-aspartate (NMDA) receptor system involvement in the mediation of analgesia. Whether or not this sex difference generalizes to other environmental stressors is, however, not clear. Biting flies are a natural aversive stimuli commonly encountered by wild and domestic animals and humans. The present study examined the opioid and non-opioid mediated nociceptive (50 degrees C hot plate) responses of reproductive male and female deer mice, Peromyscus maniculatus, exposed to biting fly attack. A 30 min exposure to biting flies (stable flies, Stomoxys calcitrans (L.)) elicited a naloxone sensitive, opioid-mediated analgesia that was of a greater magnitude in males than in female deer mice. In contrast, a 5 min exposure to biting flies elicited a 'on-opioid' analgesia that was of similar magnitude in both sexes and insensitive to both naloxone and the specific kappa opiate antagonist, nor-binaltorphimine. In male mice this non-opioid analgesia was antagonised by the competitive NMDA antagonist, NPC 1262, while in reproductive females the biting fly-induced analgesia was insensitive to NPC 12626. These results show that there are sex differences in NMDA involvement in the mediation of the non-opioid analgesia arising from brief exposure to the stress of biting fly attack. These data from a common, natural environmental challenge support the presence of basic sex difference in NMDA involvement in the mediation of stress-induced analgesia.

  19. Controlled human exposure to methyl tertiary butyl ether in gasoline: symptoms, psychophysiologic and neurobehavioral responses of self-reported sensitive persons.

    PubMed Central

    Fiedler, N; Kelly-McNeil, K; Mohr, S; Lehrer, P; Opiekun, R E; Lee, C; Wainman, T; Hamer, R; Weisel, C; Edelberg, R; Lioy, P J

    2000-01-01

    The 1990 Clean Air Act mandated oxygenation of gasoline in regions where carbon monoxide standards were not met. To achieve this standard, methyl tertiary butyl ether (MTBE) was increased to 15% by volume during winter months in many locations. Subsequent to the increase of MTBE in gasoline, commuters reported increases in symptoms such as headache, nausea, and eye, nose, and throat irritation. The present study compared 12 individuals selected based on self-report of symptoms (self-reported sensitives; SRSs) associated with MTBE to 19 controls without self-reported sensitivities. In a double-blind, repeated measures, controlled exposure, subjects were exposed for 15 min to clean air, gasoline, gasoline with 11% MTBE, and gasoline with 15% MTBE. Symptoms, odor ratings, neurobehavioral performance on a task of driving simulation, and psychophysiologic responses (heart and respiration rate, end-tidal CO(2), finger pulse volume, electromyograph, finger temperature) were measured before, during, and immediately after exposure. Relative to controls, SRSs reported significantly more total symptoms when exposed to gasoline with 15% MTBE than when exposed to gasoline with 11% MTBE or to clean air. However, these differences in symptoms were not accompanied by significant differences in neurobehavioral performance or psychophysiologic responses. No significant differences in symptoms or neurobehavioral or psychophysiologic responses were observed when exposure to gasoline with 11% MTBE was compared to clean air or to gasoline. Thus, the present study, although showing increased total symptoms among SRSs when exposed to gasoline with 15% MTBE, did not support a dose-response relationship for MTBE exposure nor the symptom specificity associated with MTBE in epidemiologic studies. Images Figure 1 Figure 2 PMID:10964796

  20. Ethanol withdrawal is required to produce persisting N-methyl-D-aspartate receptor-dependent hippocampal cytotoxicity during chronic intermittent ethanol exposure

    PubMed Central

    Reynolds, Anna R.; Berry, B. Jennifer N.; Sharrett-Field, Lynda; Prendergast, Mark A.

    2015-01-01

    Chronic intermittent ethanol consumption is associated with neurodegeneration and cognitive deficits in preclinical laboratory animals and in the clinical population. While previous work suggests a role for neuroadaptations in the N-methyl-D-aspartate (NMDA) receptor in the development of ethanol dependence and manifestation of withdrawal, the relative roles of ethanol exposure and ethanol withdrawal in producing these effects have not been fully characterized. To examine underlying cytotoxic mechanisms associated with CIE exposure, organotypic hippocampal slices were exposed to 1–3 cycles of ethanol (50 mM) in cell culture medium for 5 days, followed by 24-hours of ethanol withdrawal in which a portion of slices were exposed to competitive NMDA receptor antagonist (2R)-amino-5-phosphonovaleric acid (APV; 40 µM). Cytotoxicity was assessed using immunohistochemical labeling of neuron specific nuclear protein (NeuN; Fox-3), a marker of mature neurons, and thionine (2%) staining of Nissl bodies. Multiple cycles of CIE produced neurotoxicity, as reflected in persisting losses of neuron NeuN immunoreactivity and thionine staining in each of the primary cell layers of the hippocampal formation. Hippocampi aged in vitro were significantly more sensitive to the toxic effects of multiple CIEs than were non-aged hippocampi. This effect was not demonstrated in slices exposed to continuous ethanol, in the absence of withdrawal, or to a single exposure/withdrawal regimen. Exposure to APV significantly attenuated the cytotoxicity observed in the primary cell layers of the hippocampus. The present findings suggest that ethanol withdrawal is required to produce NMDA receptor-dependent hippocampal cytotoxicity, particularly in the aging hippocampus in vitro. PMID:25746220

  1. Investigation of drug interactions with pinaverium bromide.

    PubMed

    Devred, C; Godeau, P; Guerot, C; Librez, P; Mougeot, G; Orsetti, A; Segrestaa, J M

    1986-01-01

    A series of studies was carried out at 6 centres to investigate possible drug interaction between the spasmolytic, pinaverium bromide, and cardiac glycosides, anticoagulants and hypoglycaemic agents given to patients as part of the long-term treatment of their condition. The results of clinical and laboratory investigations did not show any evidence of pinaverium bromide interfering with the action or activity of any of the drugs studied. PMID:3084176

  2. A cross-study analysis of prenatal exposures to environmental contaminants and the epigenome: support for stress-responsive transcription factor occupancy as a mediator of gene-specific CpG methylation patterning

    PubMed Central

    Martin, Elizabeth M.; Fry, Rebecca C.

    2016-01-01

    A biological mechanism by which exposure to environmental contaminants results in gene-specific CpG methylation patterning is currently unknown. We hypothesize that gene-specific CpG methylation is related to environmentally perturbed transcription factor occupancy. To test this hypothesis, a database of 396 genes with altered CpG methylation either in cord blood leukocytes or placental tissue was compiled from 14 studies representing assessments of six environmental contaminants. Subsequently, an in silico approach was used to identify transcription factor binding sites enriched among the genes with altered CpG methylation in relationship to the suite of environmental contaminants. For each study, the sequences of the promoter regions (representing −1000 to +500 bp from the transcription start site) of all genes with altered CpG methylation were analyzed for enrichment of transcription factor binding sites. Binding sites for a total of 56 unique transcription factors were identified to be enriched within the promoter regions of the genes. Binding sites for the Kidney-Enriched Krupple-like Factor 15, a known responder to endogenous stress, were enriched (P < 0.001–0.041) among the genes with altered CpG methylation associated for five of the six environmental contaminants. These data support the transcription factor occupancy theory as a potential mechanism underlying environmentally-induced gene-specific CpG methylation. PMID:27066266

  3. Eight-five day postexposure follow-up study in Fischer 344 rats after repeated exposures to methyl isocyanate vapor

    SciTech Connect

    Fowler, E.H.; Dodd, D.E.

    1987-06-01

    The objectives of this study were to describe the microscopic lesions in the respiratory tract of Fischer 344 rats as a result of 4- or 8-days exposure (6 hr/day) of 3 ppm MIC and to characterize the postexposure development of these lesions up to day 85. All rats survived the exposure regimen, although significant decreases in body weight and encrustation of the eyes, nose, or mouth were observed. During the first 15 days of postexposure, the rats were hypoactive and had increased respiratory rates. Male mortality was as high as 63%; only 5% of the MIC-exposed females died. The cause of death was interpreted to be respiratory compromise complicated by anorexia and probably dehydration as well. During the next 28 postexposure days, 48% of the male survivors died, while only 3% of the female survivors died. Throughout the 85-day postexposure period, body weight gains in the MIC-treated groups were consistently below control values. Inflammatory and squamous metaplastic lesions of the respiratory tract, observed the day following completion of either the 4- or 8-day exposure regimen, decreased in both frequency and/or severity in survivors of the 85-day postexposure period, indicating recovery from the cytotoxic and irritating effects of MIC vapor. The squamous metaplastic epithelium was replaced by regenerative epithelium beginning in the deeper portion of the respiratory tract. Maturation of collagen occurred in the areas of submucosal fibroplasia.

  4. Relationship between Methyl Tertiary Butyl Ether Exposure and Non-Alcoholic Fatty Liver Disease: A Cross-Sectional Study among Petrol Station Attendants in Southern China.

    PubMed

    Yang, Jianping; Wei, Qinzhi; Peng, Xiaochun; Peng, Xiaowu; Yuan, Jianhui; Hu, Dalin

    2016-01-01

    Methyl tertiary butyl ether (MTBE)-A well known gasoline additive substituting for lead alkyls-causes lipid disorders and liver dysfunctions in animal models. However, whether MTBE exposure is a risk factor for non-alcoholic fatty liver disease (NAFLD) remains uncertain. We evaluate the possible relationship between MTBE exposure and the prevalence of NAFLD among 71 petrol station attendants in southern China. The personal exposure concentrations of MTBE were analyzed by Head Space Solid Phase Microextraction GC/MS. NAFLD was diagnosed by using abdominal ultrasonography according to the guidelines for the diagnosis and treatment of NAFLD suggested by the Chinese Hepatology Association. Demographic and clinical characteristics potentially associated with NAFLD were investigated. Mutivariate logistic regression analysis was applied to measure odds ratios and 95% confidence intervals (CI). The result showed that the total prevalence of NAFLD was 15.49% (11/71) among the study subjects. The average exposure concentrations of MTBE were 292.98 ± 154.90 μg/m³ and 286.64 ± 122.28 μg/m³ in NAFLD and non-NAFLD groups, respectively, and there was no statistically significant difference between them (p > 0.05). After adjusting for age, gender, physical exercise, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), alanine aminotransferase (ALT), white blood cell (WBC), total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL), the odds ratios were 1.31 (95% CI: 0.85-1.54; p > 0.05), 1.14 (95% CI: 0.81-1.32; p > 0.05), 1.52 (95% CI: 0.93-1.61; p > 0.05) in the groups (including men and women) with exposure concentrations of MTBE of 100-200 μg/m³, 200-300 μg/m³, and ≥300 μg/m³, respectively, as compared to the group (including men and women) ≤100 μg/m³. Our investigation indicates that exposure to MTBE does not seem to be a significant risk factor for the prevalence of NAFLD

  5. Relationship between Methyl Tertiary Butyl Ether Exposure and Non-Alcoholic Fatty Liver Disease: A Cross-Sectional Study among Petrol Station Attendants in Southern China.

    PubMed

    Yang, Jianping; Wei, Qinzhi; Peng, Xiaochun; Peng, Xiaowu; Yuan, Jianhui; Hu, Dalin

    2016-01-01

    Methyl tertiary butyl ether (MTBE)-A well known gasoline additive substituting for lead alkyls-causes lipid disorders and liver dysfunctions in animal models. However, whether MTBE exposure is a risk factor for non-alcoholic fatty liver disease (NAFLD) remains uncertain. We evaluate the possible relationship between MTBE exposure and the prevalence of NAFLD among 71 petrol station attendants in southern China. The personal exposure concentrations of MTBE were analyzed by Head Space Solid Phase Microextraction GC/MS. NAFLD was diagnosed by using abdominal ultrasonography according to the guidelines for the diagnosis and treatment of NAFLD suggested by the Chinese Hepatology Association. Demographic and clinical characteristics potentially associated with NAFLD were investigated. Mutivariate logistic regression analysis was applied to measure odds ratios and 95% confidence intervals (CI). The result showed that the total prevalence of NAFLD was 15.49% (11/71) among the study subjects. The average exposure concentrations of MTBE were 292.98 ± 154.90 μg/m³ and 286.64 ± 122.28 μg/m³ in NAFLD and non-NAFLD groups, respectively, and there was no statistically significant difference between them (p > 0.05). After adjusting for age, gender, physical exercise, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), alanine aminotransferase (ALT), white blood cell (WBC), total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL), the odds ratios were 1.31 (95% CI: 0.85-1.54; p > 0.05), 1.14 (95% CI: 0.81-1.32; p > 0.05), 1.52 (95% CI: 0.93-1.61; p > 0.05) in the groups (including men and women) with exposure concentrations of MTBE of 100-200 μg/m³, 200-300 μg/m³, and ≥300 μg/m³, respectively, as compared to the group (including men and women) ≤100 μg/m³. Our investigation indicates that exposure to MTBE does not seem to be a significant risk factor for the prevalence of NAFLD

  6. Relationship between Methyl Tertiary Butyl Ether Exposure and Non-Alcoholic Fatty Liver Disease: A Cross-Sectional Study among Petrol Station Attendants in Southern China

    PubMed Central

    Yang, Jianping; Wei, Qinzhi; Peng, Xiaochun; Peng, Xiaowu; Yuan, Jianhui; Hu, Dalin

    2016-01-01

    Methyl tertiary butyl ether (MTBE)—A well known gasoline additive substituting for lead alkyls—causes lipid disorders and liver dysfunctions in animal models. However, whether MTBE exposure is a risk factor for non-alcoholic fatty liver disease (NAFLD) remains uncertain. We evaluate the possible relationship between MTBE exposure and the prevalence of NAFLD among 71 petrol station attendants in southern China. The personal exposure concentrations of MTBE were analyzed by Head Space Solid Phase Microextraction GC/MS. NAFLD was diagnosed by using abdominal ultrasonography according to the guidelines for the diagnosis and treatment of NAFLD suggested by the Chinese Hepatology Association. Demographic and clinical characteristics potentially associated with NAFLD were investigated. Mutivariate logistic regression analysis was applied to measure odds ratios and 95% confidence intervals (CI). The result showed that the total prevalence of NAFLD was 15.49% (11/71) among the study subjects. The average exposure concentrations of MTBE were 292.98 ± 154.90 μg/m3 and 286.64 ± 122.28 μg/m3 in NAFLD and non-NAFLD groups, respectively, and there was no statistically significant difference between them (p > 0.05). After adjusting for age, gender, physical exercise, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), alanine aminotransferase (ALT), white blood cell (WBC), total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL), the odds ratios were 1.31 (95% CI: 0.85–1.54; p > 0.05), 1.14 (95% CI: 0.81–1.32; p > 0.05), 1.52 (95% CI: 0.93–1.61; p > 0.05) in the groups (including men and women) with exposure concentrations of MTBE of 100–200 μg/m3, 200–300 μg/m3, and ≥300 μg/m3, respectively, as compared to the group (including men and women) ≤100 μg/m3. Our investigation indicates that exposure to MTBE does not seem to be a significant risk factor for the prevalence of

  7. Abiotic Formation of Methyl Halides in the Terrestrial Environment

    NASA Astrophysics Data System (ADS)

    Keppler, F.

    2011-12-01

    Methyl chloride and methyl bromide are the most abundant chlorine and bromine containing organic compounds in the atmosphere. Since both compounds have relatively long tropospheric lifetimes they can effectively transport halogen atoms from the Earth's surface, where they are released, to the stratosphere and following photolytic oxidation form reactive halogen gases that lead to the chemical destruction of ozone. Methyl chloride and methyl bromide account for more than 20% of the ozone-depleting halogens delivered to the stratosphere and are predicted to grow in importance as the chlorine contribution to the stratosphere from anthropogenic CFCs decline. Today methyl chloride and methyl bromide originate mainly from natural sources with only a minor fraction considered to be of anthropogenic origin. However, until as recently as 2000 most of the methyl chloride and methyl bromide input to the atmosphere was considered to originate from the oceans, but investigations in recent years have clearly demonstrated that terrestrial sources such as biomass burning, wood-rotting fungi, coastal salt marshes, tropical vegetation and organic matter degradation must dominate the atmospheric budgets of these trace gases. However, many uncertainties still exist regarding strengths of both sources and sinks, as well as the mechanisms of formation of these naturally occurring halogenated gases. A better understanding of the atmospheric budget of both methyl chloride and methyl bromide is therefore required for reliable prediction of future ozone depletion. Biotic and abiotic methylation processes of chloride and bromide ion are considered to be the dominant pathways of formation of these methyl halides in nature. In this presentation I will focus on abiotic formation processes in the terrestrial environment and the potential parameters that control their emissions. Recent advances in our understanding of the abiotic formation pathway of methyl halides will be discussed. This will

  8. Differential Antioxidant Responses and Perturbed Porphyrin Biosynthesis after Exposure to Oxyfluorfen and Methyl Viologen in Oryza sativa.

    PubMed

    Pham, Nhi-Thi; Kim, Jin-Gil; Jung, Sunyo

    2015-07-21

    We compared antioxidant responses and regulation of porphyrin metabolism in rice plants treated with oxyfluorfen (OF) or methyl viologen (MV). Plants treated with MV exhibited not only greater increases in conductivity and malondialdehyde but also a greater decline in Fv/Fm, compared to plants treated with OF. MV-treated plants had greater increases in activities of superoxide dismutase (SOD) and catalase (CAT) as well as transcript levels of SODA and CATA than OF-treated plants after 28 h of the treatments, whereas increases in ascorbate peroxidase (APX) activity and transcript levels of APXA and APXB were greater in OF-treated plants. Both OF- and MV-treated plants resulted in not only down-regulation of most genes involved in porphyrin biosynthesis but also disappearance of Mg-porphyrins during the late stage of photooxidative stress. By contrast, up-regulation of heme oxygenase 2 (HO2) is possibly part of an efficient antioxidant response to compensate photooxidative damage in both treatments. Our data show that down-regulated biosynthesis and degradation dynamics of porphyrin intermediates have important roles in photoprotection of plants from perturbed porphyrin biosynthesis and photosynthetic electron transport. This study suggests that porphyrin scavenging as well as strong antioxidative activities are required for mitigating reactive oxygen species (ROS) production under photooxidative stress caused by OF and MV.

  9. Differential Antioxidant Responses and Perturbed Porphyrin Biosynthesis after Exposure to Oxyfluorfen and Methyl Viologen in Oryza sativa

    PubMed Central

    Pham, Nhi-Thi; Kim, Jin-Gil; Jung, Sunyo

    2015-01-01

    We compared antioxidant responses and regulation of porphyrin metabolism in rice plants treated with oxyfluorfen (OF) or methyl viologen (MV). Plants treated with MV exhibited not only greater increases in conductivity and malondialdehyde but also a greater decline in Fv/Fm, compared to plants treated with OF. MV-treated plants had greater increases in activities of superoxide dismutase (SOD) and catalase (CAT) as well as transcript levels of SODA and CATA than OF-treated plants after 28 h of the treatments, whereas increases in ascorbate peroxidase (APX) activity and transcript levels of APXA and APXB were greater in OF-treated plants. Both OF- and MV-treated plants resulted in not only down-regulation of most genes involved in porphyrin biosynthesis but also disappearance of Mg-porphyrins during the late stage of photooxidative stress. By contrast, up-regulation of heme oxygenase 2 (HO2) is possibly part of an efficient antioxidant response to compensate photooxidative damage in both treatments. Our data show that down-regulated biosynthesis and degradation dynamics of porphyrin intermediates have important roles in photoprotection of plants from perturbed porphyrin biosynthesis and photosynthetic electron transport. This study suggests that porphyrin scavenging as well as strong antioxidative activities are required for mitigating reactive oxygen species (ROS) production under photooxidative stress caused by OF and MV. PMID:26197316

  10. The extent to which methyl salicylate is required for signaling systemic acquired resistance is dependent on exposure to light after infection.

    PubMed

    Liu, Po-Pu; von Dahl, Caroline C; Klessig, Daniel F

    2011-12-01

    Systemic acquired resistance (SAR) is a state of heightened defense to a broad spectrum of pathogens that is activated throughout a plant following local infection. Development of SAR requires the translocation of one or more mobile signals from the site of infection through the vascular system to distal (systemic) tissues. The first such signal identified was methyl salicylate (MeSA) in tobacco (Nicotiana tabacum). Subsequent studies demonstrated that MeSA also serves as a SAR signal in Arabidopsis (Arabidopsis thaliana) and potato (Solanum tuberosum). By contrast, another study suggested that MeSA is not required for SAR in Arabidopsis and raised questions regarding its signaling role in tobacco. Differences in experimental design, including the developmental age of the plants, the light intensity, and/or the strain of bacterial pathogen, were proposed to explain these conflicting results. Here, we demonstrate that the length of light exposure that plants receive after the primary infection determines the extent to which MeSA is required for SAR signaling. When the primary infection occurred late in the day and as a result infected plants received very little light exposure before entering the night/dark period, MeSA and its metabolizing enzymes were essential for SAR development. In contrast, when infection was done in the morning followed by 3.5 h or more of exposure to light, SAR developed in the absence of MeSA. However, MeSA was generally required for optimal SAR development. In addition to resolving the conflicting results concerning MeSA and SAR, this study underscores the importance of environmental factors on the plant's response to infection.

  11. Long-lasting transcriptional refractoriness triggered by a single exposure to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyrimidine.

    PubMed

    Pattarini, R; Rong, Y; Shepherd, K R; Jiao, Y; Qu, C; Smeyne, R J; Morgan, J I

    2012-07-12

    Parkinson's disease (PD) is a progressive neurodegenerative disorder whose etiology is thought to have environmental (toxin) and genetic contributions. The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyrimidine (MPTP) induces pathological features of PD including loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and striatal dopamine (DA) depletion. We previously described the striatal transcriptional response following acute MPTP administration in MPTP-sensitive C57BL/6J mice. We identified three distinct phases: early (5h), intermediate (24h) and late (72h) and reported that the intermediate and late responses were absent in MPTP-resistant Swiss-Webster (SWR) mice. Here we show that C57BL/6J mice pre-treated with a single 40 mg/kg dose of MPTP and treated 9 days later with 4×20 mg/kg MPTP, display a striatal transcriptional response similar to that of MPTP-resistant SWR mice, i.e. a robust acute response but no intermediate or late response. Transcriptional refractoriness is dependent upon the dose of the priming challenge with as little as 10mg/kg MPTP being effective and can persist for more than 28 days. Priming of SWR mice has no effect on their response to subsequent challenge with MPTP. We also report that paraquat, another free radical producer, also elicits striatal transcriptional alterations but these are largely distinct from those triggered by MPTP. Paraquat-induced changes are also refractory to priming with paraquat. However neither paraquat nor MPTP elicits cross-attenuation. Thus exposure to specific toxins triggers distinct transcriptional responses in striatum that are influenced by prior exposure to the same toxin. The prolonged refractory period described here for MPTP could explain at the molecular level the reported discrepancies between different MPTP administration regimens and may have implications for our understanding of the relationship between environmental toxin exposure and PD.

  12. Development of a Computer-Based Survey Instrument for Organophosphate and N-Methyl-Carbamate Exposure Assessment among Agricultural Pesticide Handlers

    PubMed Central

    Hofmann, Jonathan N.; Checkoway, Harvey; Borges, Ofelio; Servin, Flor; Fenske, Richard A.; Keifer, Matthew C.

    2010-01-01

    Background: Assessment of occupational pesticide exposures based on self-reported information can be challenging, particularly with immigrant farm worker populations for whom specialized methods are needed to address language and cultural barriers and account for limited literacy. An audio computer-assisted self-interview (A-CASI) survey instrument was developed to collect information about organophosphate (OP) and N-methyl-carbamate (CB) exposures and other personal characteristics among male agricultural pesticide handlers for an ongoing cholinesterase biomonitoring study in Washington State. Objectives: To assess the feasibility of collecting data using the A-CASI instrument and evaluate reliability for a subset of survey items. Methods: The survey consisted of 64 items administered in Spanish or English on a touch-screen tablet computer. Participants listened to digitally recorded questions on headphones and selected responses on the screen, most of which were displayed as images or icons to facilitate participation of low literacy respondents. From 2006–2008, a total of 195 participants completed the survey during the OP/CB application seasons on at least one occasion. Percent agreement and kappa coefficients were calculated to evaluate test–retest reliability for selected characteristics among 45 participants who completed the survey on two separate occasions within the same year. Results: Almost all participants self-identified as Hispanic or Latino (98%), and 97% completed the survey in Spanish. Most participants completed the survey in a half-hour or less, with minimal assistance from on-site research staff. Analyses of test–retest reliability showed substantial agreement for most demographic, work history, and health characteristics and at least moderate agreement for most variables related to personal protective equipment use during pesticide applications. Conclusions: This A-CASI survey instrument is a novel method that has been used successfully

  13. Pesticide Exposure in the Caribbean: A Case From Nutmeg Processing.

    PubMed

    Akpinar-Elci, Muge; Nguyen, MyNgoc Thuy; Bidaisee, Satesh; Elci, Omur Cinai

    2016-01-01

    Many developed countries around the world have implemented regulations to phase out or greatly restrict the use of pesticides. Pesticides are still utilized with minimal restrictions, however, in fumigating agricultural commodities in developing countries such as Grenada. This special report presents the case of a nutmeg factory worker in Grenada who worked with various pesticides including methyl bromide, magnesium phosphide (magtoxin), and aluminum phosphide (phostoxin) without the proper awareness and utilization of health and safety measures. The nutmeg factory worker later developed metastatic bladder cancer, which may have been triggered by a combination of individual risk factors along with long-term occupational exposure to these pesticides. In this special report, the occupational health importance of prevention in a work environment with significant exposure to pesticides is highlighted as well as some of the fundamental deficiencies in awareness among workers in developing nations concerning the deleterious effects of frequent exposure to pesticides.

  14. Pesticide Exposure in the Caribbean: A Case From Nutmeg Processing.

    PubMed

    Akpinar-Elci, Muge; Nguyen, MyNgoc Thuy; Bidaisee, Satesh; Elci, Omur Cinai

    2016-01-01

    Many developed countries around the world have implemented regulations to phase out or greatly restrict the use of pesticides. Pesticides are still utilized with minimal restrictions, however, in fumigating agricultural commodities in developing countries such as Grenada. This special report presents the case of a nutmeg factory worker in Grenada who worked with various pesticides including methyl bromide, magnesium phosphide (magtoxin), and aluminum phosphide (phostoxin) without the proper awareness and utilization of health and safety measures. The nutmeg factory worker later developed metastatic bladder cancer, which may have been triggered by a combination of individual risk factors along with long-term occupational exposure to these pesticides. In this special report, the occupational health importance of prevention in a work environment with significant exposure to pesticides is highlighted as well as some of the fundamental deficiencies in awareness among workers in developing nations concerning the deleterious effects of frequent exposure to pesticides. PMID:26867293

  15. Methyl halides in and over the eastern Pacific (40 /sup 0/N-32 /sup 0/S)

    SciTech Connect

    Singh, H.B.; Salas, L.J.; Stiles, R.E.

    1983-04-20

    Methyl chloride, methyl bromide, and methyl iodide measurements in and over the eastern Pacific (40 /sup 0/N and 32 /sup 0/S latitude) show mean air concentrations of 633 parts per trillion (ppt), 23 ppt, and 2 ppt, and mean surface seawater concentrations of 11.5 ng/l, 1.2 ng/l, and 1.6 ng/l respectively. Long-term ambient measurements at a marine Pacific site (39 /sup 0/N) show an essentially unchanging background, with some indication of high concentrations of methyl bromide and methyl iodide during summertime. The oceanic data indicate a mean surface supersaturation of 275%, 250%, and 340%, respectively, for these three methyl halides. Depth profiles show that methyl halides are most abundant in the top mixed layer of the ocean. Oceanic concentrations of methyl chloride and methyl bromide are significantly correlated (linear regression coefficient of 0.85), suggesting a common source. No relationship between oceanic methyl iodide concentrations and the other two halides could be found. Coexistence of high concentrations of methyl iodide with relatively low concentrations of methyl chloride and vice versa provided no direct support for the hypothesis that chloride ion reactions with methyl iodide may be the dominant oceanic source of methyl chloride. For the eastern Pacific, mean ocean to air fluxes (in units of 10/sup -7/ g cm/sup -2/ yr/sup -1/) of 13,1, and 1 are determined for methyl chloride, methyl bromine, and methyl iodide, respectively. When extrapolated to global waters, they provide an adequate source to explain the atmospheric reservoir of these organic halides. Total organic bromine and iodine measurements would suggest that methyl bromide and methyl iodide contribute predominately to the tropospheric bromine and iodine organic reservoir.

  16. A study of the biological effect of continuous inhalation exposure of 1, 1, 1-trichloroethene (methyl chloroform) on animals

    NASA Technical Reports Server (NTRS)

    Macewen, J. D.; Kinkead, E. R.; Haun, C. C.

    1974-01-01

    The effects of continuous exposure to 1,1,1-trichloroethane on hepatic morphology and function are evaluated and compared with those produced by methylene chloride (dichloromethane) to determine environmental concentrations of each compound that would produce a similar biological response, i.e., a comparable increase in liver triglycerides over control levels. Experimental findings on mice, rats, dogs, and monkeys indicate that the pathological alternations observed with 1,1,1-trichloroethane are similar to those observed with dichloromethane except for different time courses of the effects and different degrees of recovery. A ten fold greater atmospheric concentration of 1,1,1-trichloroethane is required to produce the minimal liver changes found at 100 ppm dichloromethane.

  17. Sequential respiratory, psychologic, and immunologic studies in relation to methyl isocyanate exposure over two years with model development.

    PubMed Central

    Kamat, S R; Patel, M H; Pradhan, P V; Taskar, S P; Vaidya, P R; Kolhatkar, V P; Gopalani, J P; Chandarana, J P; Dalal, N; Naik, M

    1992-01-01

    Of 113 methyl isocyanate (MIC)-exposed subjects studied initially at Bhopal, India, 79, 56, 68, and 87 were followed with clinical, lung function, radiographic, and immunologic tests at 3, 6, 12, 18, and 24 months. Though our cohort consisted of subjects at all ages showing a varied severity of initial illness, fewer females and young subjects were seen. Initially all had eye problems, but dominant symptoms were exertional dyspnea, cough, chest pain, sputum, and muscle weakness. A large number showed persistent depression mixed with anxiety, with disturbances of personality parameters. The early radiographic changes were lung edema, overinflation, enlarged heart, pleural scars, and consolidation. The persistent changes seen were interstitial deposits. Lung functions showed mainly restrictive changes with small airway obstruction; there was impairment of oxygen exchange. Oxygen exchange improved at 3-6 months, and spirometry improved at 12 months, only to decline later. The expiratory flow rates pertaining to large and medium airway function improved, but those for small airways remained low. There were changes of alveolitis in bronchoalveolar lavage fluid on fiber optic bronchoscopy, and in 11 cases positive MIC-specific antibodies to IgM, IgG, and IgE were demonstrated. On follow up, only 48% of the subjects were clinically stable, while 50% showed fluctuations. Thirty-two percent of the subjects had lung function fluctuations. Detailed sequential behavior over 2-4 years was predicted for dyspnea, forced vital capacity, maximum expiratory flow rate (0.25-0.75), peak expiratory flow rate, VO2, and depression score. A model for clinical behavior explained a total variance of 52.4% by using the factors of cough, PCO2 and X-ray zones in addition to above five parameters. The behavior of the railway colony group (1640 patients) revealed a similar pattern of illness. When this observed pattern of changes was transferred to the affected Bhopal city sections (with an

  18. Mutagenic effects of lead (II) bromide.

    PubMed

    Maslat, A O; Haas, H J

    1989-12-01

    The mutagenicity of lead (II) bromide (a combustion product of the gasoline additives lead (IV) tetraethyl and 1,2-dibromoethane) was investigated using various strains of bacteria. Taking prodigiosin (the red pigment) production as a marker, lead (II) bromide was found to be mutagenic in S. marcescens, leading to the appearance of white mutant colonies that are unable to produce such a pigment. This compound was also found to be mutagenic in E. coli KMBL1851, resulting in the appearance of rifampicin-resistant mutants in addition to Met+ and His+ revertants. Some of the S. marcescens mutants were found to be reversible, able to resynthesize prodigiosin. Differences in the sensitivity to antibiotics as well as in the biochemical properties were detected between the mutants and their corresponding wild types. Lead (II) bromide gave positive results in the Ames test performed with strain TA 1535.

  19. Synthesis of deuterium labeled 17-methyl-testosterone

    SciTech Connect

    Shinohara, Y.; Baba, S.; Kasuya, Y.

    1984-09-01

    The synthesis of two forms of selectively deuterated 17-methyl-testosterone is described. 17-Methyl-d3-testosterone was prepared by the Grignard reaction of dehydroepiandrosterone with deuterium labeled methyl magnesium iodide followed by an Oppenauer oxidation. 17-Methyl-d3-testosterone-19,19,19-d3 was prepared by treating 3,3-ethylenedioxy-5,10-epoxy-5 alpha, 10 alpha-estran-17-one with deuterium labeled methyl magnesium bromide followed by hydrolysis and dehydration of the 5 alpha-hydroxyandrostane derivative.

  20. Tissue distribution and urinary excretion of inorganic arsenic and its methylated metabolites in C57BL6 mice following subchronic exposure to arsenate in drinking water

    SciTech Connect

    Kenyon, E.M. Hughes, M.F.; Adair, B.M.; Highfill, J.H.; Crecelius, E.A.; Clewell, H.J.; Yager, J.W.

    2008-11-01

    The relationship of exposure and tissue concentration of parent chemical and metabolites over prolonged exposure is a critical issue for chronic toxicities mediated by metabolite(s) rather than parent chemical alone. This is an issue for As{sup V} because its trivalent metabolites have unique toxicities and relatively greater potency compared to their pentavalent counterparts for many endpoints. In this study, dose-dependency in tissue distribution and urinary excretion for inorganic arsenic and its methylated metabolites was assessed in female C57Bl/6 mice exposed to 0, 0.5, 2, 10 or 50 ppm arsenic (as arsenate, As{sup V}) in their drinking water for 12 weeks. No adverse effects were observed and body weight gain did not differ significantly among groups. Urinary excretion of arsenite monomethylarsonous acid (MMA{sup III}), dimethylarsinous acid (DMA{sup III}), dimethylarsinic acid (DMA{sup V}), and trimethylarsine oxide (TMAO) increased linearly with dose, whereas As{sup V} and monomethylarsonic acid (MMA{sup V}) excretion was non-linear with respect to dose. Total tissue arsenic accumulation was greatest in kidney > lung > urinary bladder >>> skin > blood > liver. Monomethyl arsenic (MMA, i.e. MMA{sup III} + MMA{sup V}) was the predominant metabolite in kidney, whereas dimethylarsenic (DMA, i.e., DMA{sup III} + DMA{sup V}) was the predominant metabolite in lung. Urinary bladder tissue had roughly equivalent levels of inorganic arsenic and dimethylarsenic, as did skin. These data indicate that pharmacokinetic models for arsenic metabolism and disposition need to include mechanisms for organ-specific accumulation of some arsenicals and that urinary metabolite profiles are not necessarily reflective of target tissue dosimetry.

  1. Effects of pinaverium bromide on Oddi's sphincter.

    PubMed

    DiSomma, C; Reboa, G; Patrone, M G; Mortola, G P; Sala, G; Ciampini, M

    1986-01-01

    Twelve to 15 days after cholecystectomy, endocholedochal pressure was measured in ten patients before and one hour after oral administration of 15 mg of pinaverium bromide (six patients) or placebo. The mean endocholedochal pressure was 7.1 +/- 0.25 mmHg before and 3.1 +/- 0.2 mmHg after pinaverium (P less than 0.01), and 7.0 +/- 0.2 and 6.8 +/- 1.2 mmHg in the placebo-treated patients. The results suggest that pinaverium bromide has a specific effect on the common bile duct and probably on Oddi's sphincter. PMID:3815457

  2. [The clinical pharmacological profile of pinaverium bromide].

    PubMed

    Guslandi, M

    1994-04-01

    Pinaverium bromide is a locally acting spasmolytic agent of the digestive tract. Its mechanism of action relies upon inhibition of calcium ion entrance into smooth muscle cells (calcium-antagonist effect). In humans pinaverium facilitates gastric emptying and decreases intestinal transit time in patients with constipation. Pinaverium is very effective in improving symptoms of irritable bowel syndrome (abdominal pain, gas, diarrhea or constipation). In this respect the drug proved to be significantly superior to placebo, at least as effective as trimebutine and on the whole more active than otilonium and prifinium bromide, being always extremely well tolerated. PMID:8028745

  3. VITRIFICATION OF THAI NATIVE CATTLE OOCYTES: EFFECTS OF ETHYLENE GLYCOL CONCENTRATIONS AND EXPOSURE TIME, LINOLEIC ACID ALBUMIN AND CHOLESTEROL-LOADED METHYL-B-CYCLODEXTRIN.

    PubMed

    Chasombat, Jakkhaphan; Vongpralub, Thevin; Sirisathien, Saksiri; Phasuk, Yupin; Sonseeda, Pronjit

    2015-01-01

    The present study aimed to improve the oocyte vitrification procedure for preservation of Thai native cattle genetic resources. In Experiment I, oocytes were exposed to various doses (2%, 4% and 6%) of ethylene glycol (EG) in vitrification solution I (VS-I) for different equilibration times (10 or 20 min) before being exposed to VS-II and then subjected to vitrification. Experiment II was divided into two parts: (a) oocytes were matured in medium supplemented with linoleic acid albumin (LAA) (1% or 2%) and then vitrified; (b) matured oocytes were preincubated with cholesterol-loaded methyl-β-cyclodextrin (CLC) (1% or 2%) and then vitrified. Equilibration of oocytes by exposure to 6% EG in VS-I for 10 min (Experiment I), and in vitro maturation of immature oocytes in medium supplementation with 2% LAA (Experiment II) were the most effective methods; vitrified/thawed oocytes showed higher rates of survival and subsequent embryonic development compared with the other experimental groups. PMID:26510334

  4. Methyl Halide Production by Fungi

    NASA Astrophysics Data System (ADS)

    Dailey, G. D.; Varner, R. K.; Blanchard, R. O.; Sive, B. C.; Crill, P. M.

    2005-12-01

    Methyl chloride (CH3Cl), methyl bromide (CH3Br) and methyl iodide (CH3I) are methyl halide gases that contribute significant amounts of halogen radicals to the atmosphere. In an effort to better understand the global budget of methyl halides and their impact on the atmosphere, we need to identify the natural sources in addition to the known anthropogenic sources of these compounds. We are investigating the role of fungi in the production of methyl halides in the soils and wetlands in southern New Hampshire, USA. Previous research has shown that wood decay fungi and ectomycorrhizal fungi, which are within a group of fungi called basidiomycetes, emit methyl halides. In our study, measurements of headspace gas extracted from flasks containing fungi grown in culture demonstrate that a variety of fungi, including basidiomycetes and non-basidiomycetes, emit methyl halides. Our research sites include four ecosystems: an agricultural field, a temperate forest, a fresh water wetland, and coastal salt marshes. We have collected and isolated fungi at each site by culturing tissue samples of fruiting bodies and plant material, by using wood baits, and from the direct culture of soil. We compared the rates of methyl halide emissions from the fungi in the four ecosystems. In addition, we measured emissions from previously assayed fungal isolates after reintroducing them to sterilized soils that were collected from their original environments. Fungal biomass was determined by substrate-induced respiration (SIR). The emission rate by the fungus was determined by a linear regression of the concentration of methyl halide in the sample headspace over time divided by the fungal biomass.

  5. Long-term pancreatic beta cell exposure to high levels of glucose but not palmitate induces DNA methylation within the insulin gene promoter and represses transcriptional activity.

    PubMed

    Ishikawa, Kota; Tsunekawa, Shin; Ikeniwa, Makoto; Izumoto, Takako; Iida, Atsushi; Ogata, Hidetada; Uenishi, Eita; Seino, Yusuke; Ozaki, Nobuaki; Sugimura, Yoshihisa; Hamada, Yoji; Kuroda, Akio; Shinjo, Keiko; Kondo, Yutaka; Oiso, Yutaka

    2015-01-01

    Recent studies have implicated epigenetics in the pathophysiology of diabetes. Furthermore, DNA methylation, which irreversibly deactivates gene transcription, of the insulin promoter, particularly the cAMP response element, is increased in diabetes patients. However, the underlying mechanism remains unclear. We aimed to investigate insulin promoter DNA methylation in an over-nutrition state. INS-1 cells, the rat pancreatic beta cell line, were cultured under normal-culture-glucose (11.2 mmol/l) or experimental-high-glucose (22.4 mmol/l) conditions for 14 days, with or without 0.4 mmol/l palmitate. DNA methylation of the rat insulin 1 gene (Ins1) promoter was investigated using bisulfite sequencing and pyrosequencing analysis. Experimental-high-glucose conditions significantly suppressed insulin mRNA and increased DNA methylation at all five CpG sites within the Ins1 promoter, including the cAMP response element, in a time-dependent and glucose concentration-dependent manner. DNA methylation under experimental-high-glucose conditions was unique to the Ins1 promoter; however, palmitate did not affect DNA methylation. Artificial methylation of Ins1 promoter significantly suppressed promoter-driven luciferase activity, and a DNA methylation inhibitor significantly improved insulin mRNA suppression by experimental-high-glucose conditions. Experimental-high-glucose conditions significantly increased DNA methyltransferase activity and decreased ten-eleven-translocation methylcytosine dioxygenase activity. Oxidative stress and endoplasmic reticulum stress did not affect DNA methylation of the Ins1 promoter. High glucose but not palmitate increased ectopic triacylglycerol accumulation parallel to DNA methylation. Metformin upregulated insulin gene expression and suppressed DNA methylation and ectopic triacylglycerol accumulation. Finally, DNA methylation of the Ins1 promoter increased in isolated islets from Zucker diabetic fatty rats. This study helps to clarify the

  6. Prenatal Exposure to Maternal Cigarette Smoking and DNA Methylation: Epigenome-Wide Association in a Discovery Sample of Adolescents and Replication in an Independent Cohort at Birth through 17 Years of Age

    PubMed Central

    Lee, Ken W.K.; Richmond, Rebecca; Hu, Pingzhao; French, Leon; Shin, Jean; Bourdon, Celine; Reischl, Eva; Waldenberger, Melanie; Zeilinger, Sonja; Gaunt, Tom; McArdle, Wendy; Ring, Susan; Woodward, Geoff; Bouchard, Luigi; Gaudet, Daniel; Smith, George Davey; Relton, Caroline; Paus, Tomas

    2014-01-01

    Background: Prenatal exposure to maternal cigarette smoking (prenatal smoke exposure) had been associated with altered DNA methylation (DNAm) at birth. Objective: We examined whether such alterations are present from birth through adolescence. Methods: We used the Infinium HumanMethylation450K BeadChip to search across 473,395 CpGs for differential DNAm associated with prenatal smoke exposure during adolescence in a discovery cohort (n = 132) and at birth, during childhood, and during adolescence in a replication cohort (n = 447). Results: In the discovery cohort, we found five CpGs in MYO1G (top-ranking CpG: cg12803068, p = 3.3 × 10–11) and CNTNAP2 (cg25949550, p = 4.0 × 10–9) to be differentially methylated between exposed and nonexposed individuals during adolescence. The CpGs in MYO1G and CNTNAP2 were associated, respectively, with higher and lower DNAm in exposed versus nonexposed adolescents. The same CpGs were differentially methylated at birth, during childhood, and during adolescence in the replication cohort. In both cohorts and at all developmental time points, the differential DNAm was in the same direction and of a similar magnitude, and was not altered appreciably by adjustment for current smoking by the participants or their parents. In addition, four of the five EWAS (epigenome-wide association study)–significant CpGs in the adolescent discovery cohort were also among the top sites of differential methylation in a previous birth cohort, and differential methylation of CpGs in CYP1A1, AHRR, and GFI1 observed in that study was also evident in our discovery cohort. Conclusions: Our findings suggest that modifications of DNAm associated with prenatal maternal smoking may persist in exposed offspring for many years—at least until adolescence. Citation: Lee KW, Richmond R, Hu P, French L, Shin J, Bourdon C, Reischl E, Waldenberger M, Zeilinger S, Gaunt T, McArdle W, Ring S, Woodward G, Bouchard L, Gaudet D, Davey Smith G, Relton C, Paus T

  7. Laser Raman spectroscopy study of the zinc and bromide ion complex equilibrium in zinc/bromine battery electrolytes. [2M ZnBr/sub 2/ and 1M KBr solution

    SciTech Connect

    Grimes, P.G.; Larrabee, J.A.

    1985-01-01

    Laser Raman spectroscopy was used to study the zinc and bromide ion complex equilibrium in zinc bromine battery model electrolytes. Solutions of zinc bromide with added KBr, HBr and N-methyl, N-ethyl morpholinium (MEM) bromide were examined and compared. Solutions studied ranged from 1 to 3 molar in zinc and from 2.5 to 8 molar in bromide. A typical Raman spectrum of a zinc bromide solution is shown in Figure 1. Each of the zinc species is identified, Zn/sup + +/ (aq), ZnBr/sup +/, ZnBr/sub 2/ (aq), ZnBr/sub 3//sup -/ and ZnBr/sub 4//sup 2 -/. By the use of peak heights or deconvolution/integration along with published Raman cross sections, the amount of each zinc species could be quantitatively determined. The addition of bromide ions to the zinc bromide solutions will shift the equilibrium toward higher bromide complexes. The added cations will influence the shifts. It has been noted that the conductivity of the electrolyte decreases when the quaternary ammonium ions are present compared to cations such as potassium or hydrogen. Significantly more free zinc is present in zinc bromide solutions with added KBr than with either MEMBr or HBr. Shifts are also noted with the other zinc ion containing species. It appears that the quaternary ammonium ions and possibly the pH could have a stabilizing effect on zinc bromide complex ion formation. 2 figs.

  8. Zinc Bromide Waste Solution Treatment Options

    SciTech Connect

    Langston, C.A.

    2001-01-16

    The objective of this effort was to identify treatment options for 20,000 gallons of low-level radioactively contaminated zinc bromide solution currently stored in C-Area. These options will be relevant when the solutions are declared waste.

  9. A comparison of the action of otilonium bromide and pinaverium bromide: study conducted under clinical control.

    PubMed

    Defrance, P; Casini, A

    1991-11-01

    We studied 40 patients with irritable bowel syndrome (IBS) which received in a simple-blind fashion otilonium and pinaverium bromide (15 days each drug). During each 15-day period we evaluated: number of pain episodes, intensity of pain, number of bowel movements, side effects. Otilonium bromide, (OB), compared with pinaverium bromide was able to significantly (p less than 0.05) reduce the number of pain attacks, whereas no significant differences were found between the 2 groups as regards the other parameters. The occurrence of side effects was similar in the two treatment courses. We can conclude that the two types of treatment were similarly useful in IBS, although OB seems more effective than pinaverium bromide. PMID:1756286

  10. Flow injection determination of bromide ion in a developer using bromide ion-selective electrode detector.

    PubMed

    Masadome, T; Asano, Y; Nakamura, T

    1999-10-01

    A potentiometric flow injection determination method for bromide ion in a developer was proposed, by utilizing a flow-through type bromide ion-selective electrode detector. The sensing membrane of the electrode was Ag(2)S-AgBr membrane. The response of the electrode detector as a peak-shape signal was obtained for injected bromide ion in a developer. A linear relationship was found to exist between peak height and the concentration of the bromide ion in a developer in a concentration range from 1.0x10(-3) to 1.0x10(-2) mol l(-1). The relative standard deviation for 10 injections of a 6x10(-3) mol l(-1) bromide ion in a developer was 1.3% and the sampling rate was ca 17-20 samples h(-1). The present method was free from the interference of an organic reducing reagent, an organic substance in a developer sample solution for the determination of bromide ion in a developer.

  11. Characterizing the Sources and Sinks of Methyl Halides in the Florida Everglades and Coastal Waters by Isotopic Analysis

    NASA Astrophysics Data System (ADS)

    Scully, N. M.; Jones, R. D.; Raffel, A.; Rice, A. L.

    2012-12-01

    Recent studies have demonstrated that the methyl halides, methyl chloride and methyl bromide, are produced in significant quantities by phytoplankton and by the photochemical oxidation of dissolved organic matter (DOM). However, we know little of the mechanisms responsible for the photochemical production of methyl halides and also the factors which affect the microbial formation and consumption in the surface waters. We are currently conducting laboratory experiments to elucidate the mechanisms responsible for the photochemical and microbial formation and consumption of methyl chloride and methyl bromide in the Florida Everglades and coastal waters. We present data from laboratory experiments using a stable isotope spiking tracer method to quantify photochemical flux rates of methyl chloride and methyl bromide from wetland and estuarine water samples collected at FCE-LTER sites located in Taylor Slough and Florida Bay. These photochemical experiments include waters that span a wide range of halide and DOM concentrations. We use these results to estimate the net photochemical flux of methyl chloride and methyl bromide from the Florida Everglades. We have also conducted stable carbon isotope analysis of the methyl chloride. These experiments are being conducted to determine the carbon isotopic ratios (d13C) of methyl chloride produced from the photolysis of organic matter in natural waters and will provide an inventory of d13C values from one of the sources within the studied Everglades ecotones. This research was supported by the National Science Foundation Chemical Oceanography Program Award No. 1029710.

  12. 21 CFR 522.275 - N-Butylscopolammonium bromide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false N-Butylscopolammonium bromide. 522.275 Section 522....275 N-Butylscopolammonium bromide. (a) Specifications. Each milliliter of solution contains 20 milligrams (mg) N-butylscopolammonium bromide. (b) Sponsor. See No. 000010 in § 510.600(c) of this...

  13. 21 CFR 522.275 - N-Butylscopolammonium bromide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false N-Butylscopolammonium bromide. 522.275 Section 522....275 N-Butylscopolammonium bromide. (a) Specifications. Each milliliter of solution contains 20 milligrams (mg) N-butylscopolammonium bromide. (b) Sponsor. See No. 000010 in § 510.600(c) of this...

  14. 21 CFR 522.275 - N-Butylscopolammonium bromide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false N-Butylscopolammonium bromide. 522.275 Section 522....275 N-Butylscopolammonium bromide. (a) Specifications. Each milliliter of solution contains 20 milligrams (mg) N-butylscopolammonium bromide. (b) Sponsor. See No. 000010 in § 510.600(c) of this...

  15. 21 CFR 522.275 - N-Butylscopolammonium bromide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false N-Butylscopolammonium bromide. 522.275 Section 522....275 N-Butylscopolammonium bromide. (a) Specifications. Each milliliter of solution contains 20 milligrams (mg) N-butylscopolammonium bromide. (b) Sponsor. See No. 000010 in § 510.600(c) of this...

  16. Maternal exposure to anti-androgenic compounds, vinclozolin, flutamide and procymidone, has no effects on spermatogenesis and DNA methylation in male rats of subsequent generations

    SciTech Connect

    Inawaka, Kunifumi Kawabe, Mayumi; Takahashi, Satoru; Doi, Yuko; Tomigahara, Yoshitaka; Tarui, Hirokazu; Abe, Jun; Kawamura, Satoshi; Shirai, Tomoyuki

    2009-06-01

    To verify whether anti-androgens cause transgenerational effects on spermatogenesis and DNA methylation in rats, gravid Crl:CD(SD) female rats (4 or 5/group, gestational day (GD) 0 = day sperm detected) were intraperitoneally treated with anti-androgenic compounds, such as vinclozolin (100 mg/kg/day), procymidone (100 mg/kg/day), or flutamide (10 mg/kg/day), from GD 8 to GD 15. Testes were collected from F1 male pups at postnatal day (PND) 6 for DNA methylation analysis of the region (210 bp including 7 CpG sites) within the lysophospholipase gene by bisulfite DNA sequencing method. F0 and F1 males underwent the sperm analysis (count, motility and morphology), followed by DNA methylation analysis of the sperm. Remaining F1 males were cohabited with untreated-females to obtain F2 male pups for subsequent DNA methylation analysis of the testes at PND 6. These analyses showed no effects on spermatogenesis and fertility in F1 males of any treatment group. DNA methylation status in testes (F1 and F2 pups at PND 6) or sperms (F1 males at 13 weeks old) of the treatment groups were comparable to the control at all observation points, although DNA methylation rates in testes were slightly lower than those in sperm. In F0 males, no abnormalities in the spermatogenesis, fertility and DNA methylation status of sperm were observed. No transgenerational abnormalities of spermatogenesis and DNA methylation status caused by anti-androgenic compounds were observed.

  17. Methylation matters

    PubMed Central

    Costello, J.; Plass, C.

    2001-01-01

    DNA methylation is not just for basic scientists any more. There is a growing awareness in the medical field that having the correct pattern of genomic methylation is essential for healthy cells and organs. If methylation patterns are not properly established or maintained, disorders as diverse as mental retardation, immune deficiency, and sporadic or inherited cancers may follow. Through inappropriate silencing of growth regulating genes and simultaneous destabilisation of whole chromosomes, methylation defects help create a chaotic state from which cancer cells evolve. Methylation defects are present in cells before the onset of obvious malignancy and therefore cannot be explained simply as a consequence of a deregulated cancer cell. Researchers are now able to detect with exquisite sensitivity the cells harbouring methylation defects, sometimes months or years before the time when cancer is clinically detectable. Furthermore, aberrant methylation of specific genes has been directly linked with the tumour response to chemotherapy and patient survival. Advances in our ability to observe the methylation status of the entire cancer cell genome have led us to the unmistakable conclusion that methylation abnormalities are far more prevalent than expected. This methylomics approach permits the integration of an ever growing repertoire of methylation defects with the genetic alterations catalogued from tumours over the past two decades. Here we discuss the current knowledge of DNA methylation in normal cells and disease states, and how this relates directly to our current understanding of the mechanisms by which tumours arise.


Keywords: methylation; cancer PMID:11333864

  18. Methylation of NR3C1 is related to maternal PTSD, parenting stress and maternal medial prefrontal cortical activity in response to child separation among mothers with histories of violence exposure

    PubMed Central

    Schechter, Daniel S.; Moser, Dominik A.; Paoloni-Giacobino, Ariane; Stenz, Ludwig; Gex-Fabry, Marianne; Aue, Tatjana; Adouan, Wafae; Cordero, María I.; Suardi, Francesca; Manini, Aurelia; Sancho Rossignol, Ana; Merminod, Gaëlle; Ansermet, Francois; Dayer, Alexandre G.; Rusconi Serpa, Sandra

    2015-01-01

    Prior research has shown that mothers with Interpersonal violence-related posttraumatic stress disorder (IPV-PTSD) report greater difficulty in parenting their toddlers. Relative to their frequent early exposure to violence and maltreatment, these mothers display dysregulation of their hypothalamic pituitary adrenal axis (HPA-axis), characterized by hypocortisolism. Considering methylation of the promoter region of the glucocorticoid receptor gene NR3C1 as a marker for HPA-axis functioning, with less methylation likely being associated with less circulating cortisol, the present study tested the hypothesis that the degree of methylation of this gene would be negatively correlated with maternal IPV-PTSD severity and parenting stress, and positively correlated with medial prefrontal cortical (mPFC) activity in response to video-stimuli of stressful versus non-stressful mother–child interactions. Following a mental health assessment, 45 mothers and their children (ages 12–42 months) participated in a behavioral protocol involving free-play and laboratory stressors such as mother–child separation. Maternal DNA was extracted from saliva. Interactive behavior was rated on the CARE-Index. During subsequent fMRI scanning, mothers were shown films of free-play and separation drawn from this protocol. Maternal PTSD severity and parenting stress were negatively correlated with the mean percentage of methylation of NR3C1. Maternal mPFC activity in response to video-stimuli of mother–child separation versus play correlated positively to NR3C1 methylation, and negatively to maternal IPV-PTSD and parenting stress. Among interactive behavior variables, child cooperativeness in play was positively correlated with NR3C1 methylation. Thus, the present study is the first published report to our knowledge, suggesting convergence of behavioral, epigenetic, and neuroimaging data that form a psychobiological signature of parenting-risk in the context of early life stress and PTSD

  19. Genetic control of methyl halide production in Arabidopsis.

    PubMed

    Rhew, Robert C; Østergaard, Lars; Saltzman, Eric S; Yanofsky, Martin F

    2003-10-14

    Methyl chloride (CH(3)Cl) and methyl bromide (CH(3)Br) are the primary carriers of natural chlorine and bromine, respectively, to the stratosphere, where they catalyze the destruction of ozone, whereas methyl iodide (CH(3)I) influences aerosol formation and ozone loss in the boundary layer. CH(3)Br is also an agricultural pesticide whose use is regulated by international agreement. Despite the economic and environmental importance of these methyl halides, their natural sources and biological production mechanisms are poorly understood. Besides CH(3)Br fumigation, important sources include oceans, biomass burning, tropical plants, salt marshes, and certain crops and fungi. Here, we demonstrate that the model plant Arabidopsis thaliana produces and emits methyl halides and that the enzyme primarily responsible for the production is encoded by the HARMLESS TO OZONE LAYER (HOL) gene. The encoded protein belongs to a group of methyltransferases capable of catalyzing the S-adenosyl-L-methionine (SAM)-dependent methylation of chloride (Cl(-)), bromide (Br(-)), and iodide (I(-)) to produce methyl halides. In mutant plants with the HOL gene disrupted, methyl halide production is largely eliminated. A phylogenetic analysis with the HOL gene suggests that the ability to produce methyl halides is widespread among vascular plants. This approach provides a genetic basis for understanding and predicting patterns of methyl halide production by plants.

  20. Colon cancer cell apoptosis is induced by combined exposure to the n-3 fatty acid docosahexaenoic acid and butyrate through promoter methylation.

    PubMed

    Cho, Youngmi; Turner, Nancy D; Davidson, Laurie A; Chapkin, Robert S; Carroll, Raymond J; Lupton, Joanne R

    2014-03-01

    DNA methylation and histone acetylation contribute to the transcriptional regulation of genes involved in apoptosis. We have demonstrated that docosahexaenoic acid (DHA, 22:6 n-3) and butyrate enhance colonocyte apoptosis. To determine if DHA and/or butyrate elevate apoptosis through epigenetic mechanisms thereby restoring the transcription of apoptosis-related genes, we examined global methylation; gene-specific promoter methylation of 24 apoptosis-related genes; transcription levels of Cideb, Dapk1, and Tnfrsf25; and global histone acetylation in the HCT-116 colon cancer cell line. Cells were treated with combinations of (50 µM) DHA or linoleic acid (18:2 n-6), (5 mM) butyrate or an inhibitor of DNA methyltransferases, and 5-aza-2'-deoxycytidine (5-Aza-dC, 2 µM). Among highly methylated genes, the combination of DHA and butyrate significantly reduced methylation of the proapoptotic Bcl2l11, Cideb, Dapk1, Ltbr, and Tnfrsf25 genes compared to untreated control cells. DHA treatment reduced the methylation of Cideb, Dapk1, and Tnfrsf25. These data suggest that the induction of apoptosis by DHA and butyrate is mediated, in part, through changes in the methylation state of apoptosis-related genes.

  1. Removal of bromide and natural organic matter by anion exchange.

    PubMed

    Hsu, Susan; Singer, Philip C

    2010-04-01

    Bromide removal by anion exchange was explored for various water qualities, process configurations, and resin characteristics. Simulated natural waters containing different amounts of natural organic matter (NOM), bicarbonate, chloride, and bromide were treated with a polyacrylate-based magnetic ion exchange (MIEX) resin on a batch basis to evaluate the effectiveness of the resin for removal of bromide. While bromide removal was achieved to some degree, alkalinity (bicarbonate), dissolved organic carbon (DOC), and chloride were shown to inhibit bromide removal in waters with bromide concentrations of 100 and 300 microg/L. Water was also treated using a two-stage batch MIEX process. Two-stage treatment resulted in only a slight improvement in bromide removal compared to single-stage treatment, presumably due to competition with the high concentration of chloride which is present along with bromide in natural waters. In view of the relatively poor bromide removal results for the MIEX resin, a limited set of experiments was performed using polystyrene resins. DOC and bromide removal were compared by treating model waters with MIEX and two polystyrene resins, Ionac A-641 and Amberlite IRA910. The two polystyrene resins were seen to be more effective for bromide removal, while the MIEX resin was more effective at removing DOC.

  2. Exposure of E. coli to DNA-Methylating Agents Impairs Biofilm Formation and Invasion of Eukaryotic Cells via Down Regulation of the N-Acetylneuraminate Lyase NanA

    PubMed Central

    Di Pasquale, Pamela; Caterino, Marianna; Di Somma, Angela; Squillace, Marta; Rossi, Elio; Landini, Paolo; Iebba, Valerio; Schippa, Serena; Papa, Rosanna; Selan, Laura; Artini, Marco; Palamara, Anna Teresa; Duilio, Angela

    2016-01-01

    DNA methylation damage can be induced by endogenous and exogenous chemical agents, which has led every living organism to develop suitable response strategies. We investigated protein expression profiles of Escherichia coli upon exposure to the alkylating agent methyl-methane sulfonate (MMS) by differential proteomics. Quantitative proteomic data showed a massive downregulation of enzymes belonging to the glycolytic pathway and fatty acids degradation, strongly suggesting a decrease of energy production. A strong reduction in the expression of the N-acetylneuraminate lyases (NanA) involved in the sialic acid metabolism was also observed. Using a null NanA mutant and DANA, a substrate analog acting as competitive inhibitor, we demonstrated that down regulation of NanA affects biofilm formation and adhesion properties of E. coli MV1161. Exposure to alkylating agents also decreased biofilm formation and bacterial adhesion to Caco-2 eukaryotic cell line by the adherent invasive E. coli (AIEC) strain LF82. Our data showed that methylation stress impairs E. coli adhesion properties and suggest a possible role of NanA in biofilm formation and bacteria host interactions. PMID:26904018

  3. Exposure of E. coli to DNA-Methylating Agents Impairs Biofilm Formation and Invasion of Eukaryotic Cells via Down Regulation of the N-Acetylneuraminate Lyase NanA.

    PubMed

    Di Pasquale, Pamela; Caterino, Marianna; Di Somma, Angela; Squillace, Marta; Rossi, Elio; Landini, Paolo; Iebba, Valerio; Schippa, Serena; Papa, Rosanna; Selan, Laura; Artini, Marco; Palamara, Anna Teresa; Palamara, Annateresa; Duilio, Angela

    2016-01-01

    DNA methylation damage can be induced by endogenous and exogenous chemical agents, which has led every living organism to develop suitable response strategies. We investigated protein expression profiles of Escherichia coli upon exposure to the alkylating agent methyl-methane sulfonate (MMS) by differential proteomics. Quantitative proteomic data showed a massive downregulation of enzymes belonging to the glycolytic pathway and fatty acids degradation, strongly suggesting a decrease of energy production. A strong reduction in the expression of the N-acetylneuraminate lyases (NanA) involved in the sialic acid metabolism was also observed. Using a null NanA mutant and DANA, a substrate analog acting as competitive inhibitor, we demonstrated that down regulation of NanA affects biofilm formation and adhesion properties of E. coli MV1161. Exposure to alkylating agents also decreased biofilm formation and bacterial adhesion to Caco-2 eukaryotic cell line by the adherent invasive E. coli (AIEC) strain LF82. Our data showed that methylation stress impairs E. coli adhesion properties and suggest a possible role of NanA in biofilm formation and bacteria host interactions.

  4. Mitigating 1,3-dichloropropene, chloropicrin, and methyl iodide emissions from fumigated soil with reactive film

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Implicated as a stratospheric ozone-depleting compound, methyl bromide (MeBr) is being phased out despite being considered to be the most effective soil fumigant. Its alternatives, i.e., 1,3-dichloropropene (1,3-D, which includes cis- and trans- isomers), chloropicrin (CP) and methyl iodide (MeI), h...

  5. 40 CFR 180.123 - Inorganic bromide residues resulting from fumigation with methyl bromide; tolerances for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... residues are present in malt beverage, fermented in accordance with 21 CFR 172.730(a)(2), the amount shall..., postharvest 5.0 Apricot, postharvest 20.0 Artichoke, jerusalem, postharvest 30.0 Asparagus, postharvest...

  6. 40 CFR 180.123 - Inorganic bromide residues resulting from fumigation with methyl bromide; tolerances for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 21 CFR 172.730(a)(2), the amount shall not exceed 25 parts per million (calculated as Br). (iii... parts per million in or on egg, dried and herb, processed and spice. (B) 325 parts per million in or...

  7. 40 CFR 180.123 - Inorganic bromide residues resulting from fumigation with methyl bromide; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 21 CFR 172.730(a)(2), the amount shall not exceed 25 parts per million (calculated as Br). (iii... parts per million in or on egg, dried and herb, processed and spice. (B) 325 parts per million in or...

  8. 40 CFR 180.123 - Inorganic bromide residues resulting from fumigation with methyl bromide; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 21 CFR 172.730(a)(2), the amount shall not exceed 25 parts per million (calculated as Br). (iii... parts per million in or on egg, dried and herb, processed and spice. (B) 325 parts per million in or...

  9. 40 CFR 180.123 - Inorganic bromide residues resulting from fumigation with methyl bromide; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 21 CFR 172.730(a)(2), the amount shall not exceed 25 parts per million (calculated as Br). (iii... parts per million in or on egg, dried and herb, processed and spice. (B) 325 parts per million in or...

  10. Europium-doped barium bromide iodide

    SciTech Connect

    Gundiah, Gautam; Hanrahan, Stephen M.; Hollander, Fredrick J.; Bourret-Courchesne, Edith D.

    2009-10-21

    Single crystals of Ba0.96Eu0.04BrI (barium europium bromide iodide) were grown by the Bridgman technique. The title compound adopts the ordered PbCl2 structure [Braekken (1932). Z. Kristallogr. 83, 222-282]. All atoms occupy the fourfold special positions (4c, site symmetry m) of the space group Pnma with a statistical distribution of Ba and Eu. They lie on the mirror planes, perpendicular to the b axis at y = +-0.25. Each cation is coordinated by nine anions in a tricapped trigonal prismatic arrangement.

  11. Biomonitoring the Cooked Meat Carcinogen 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in Hair: Impact of Exposure, Pigmentation and Cytochrome P450 1A2 Phenotype

    PubMed Central

    Turesky, Robert J.; Liu, Lin; Gu, Dan; Yonemori, Kim M.; White, Kami K.; Wilkens, Lynne R.; Marchand, Loic Le

    2013-01-01

    Background Hair is a promising tissue to assess exposure to 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a carcinogen formed in cooked meats. However, an understanding of how dietary exposure to PhIP, cytochrome P450 1A2 activity - a key enzyme involved in PhIP metabolism, and hair pigmentation affect the level of PhIP accrued in hair is required in order to determine the reliability of the PhIP hair level as a biomarker of exposure to this carcinogen. Methods We examined the impact of PhIP exposure, cytochrome P450 1A2 activity, and hair pigmentation on the levels of PhIP accumulated in the hair of volunteers on a 4-week semi-controlled diet of cooked meat containing known quantities of PhIP. Results The amount of PhIP in hair increased, on average, 15-fold in light- and dark-haired individuals during consumption of cooked meat. PhIP levels in hair were correlated to PhIP intake (ρ = 0.53; p < 0.001), and the relationship was strengthened when PhIP levels were normalized for the melanin content of hair (ρ = 0.71; p < 0.001). However, PhIP accrual in hair was not correlated to cytochrome P450 1A2 activity, as assessed by the caffeine test, or to the levels of unmetabolized PhIP in urine, or to the metabolic ratio of the major urinary metabolite N2-(ß-1-glucosiduronyl-2-(hydroxyamino)-1-methyl-6-phenylimidazo[4,5-b]pyridine to unmetabolized PhIP. Conclusions The employment of the PhIP hair biomarker should take hair pigmentation into account for accurate exposure assessment. Impact PhIP hair levels can serve as a biomarker in epidemiological studies investigating the association of HAAs, cooked meat and cancer risk. PMID:23329727

  12. Advanced hydrogen electrode for hydrogen-bromide battery

    NASA Technical Reports Server (NTRS)

    Kosek, Jack A.; Laconti, Anthony B.

    1987-01-01

    Binary platinum alloys are being developed as hydrogen electrocatalysts for use in a hydrogen bromide battery system. These alloys were varied in terms of alloy component mole ratio and heat treatment temperature. Electrocatalyst evaluation, performed in the absence and presence of bromide ion, includes floating half cell polarization studies, electrochemical surface area measurements, X ray diffraction analysis, scanning electron microscopy analysis and corrosion measurements. Results obtained to date indicate a platinum rich alloy has the best tolerance to bromide ion poisoning.

  13. Methylation-sensitive polymerase chain reaction.

    PubMed

    Moore, Hannah R; Meehan, Richard R; Young, Lorraine E

    2006-01-01

    Here, we describe a robust and reproducible methylation-sensitive polymerase chain reaction (MS-PCR) method to detect the percentage methylation in repeat sequences of individual pre-implantation ovine embryos produced by different embryo technologies. This method allows the comparison of embryos produced by nuclear transfer with other production and embryo culture methods, accounting for the heterogeneity between embryos within a single treatment. DNA extracted from single embryos is digested with a methylation-sensitive restriction enzyme to determine the percentage methylation after PCR amplification in comparison with an undigested control. The undigested control represents 100% methylation because methylation-sensitive enzymes do not cut methylated DNA, allowing the entire sample to be amplified by PCR. Image analysis quantification of the digested subsample PCR product on an ethidium bromide-stained agarose gel is proportional to the amount of methylated DNA in each embryo. By comparing quadruplicate values obtained for each embryo against a standard curve, we are able to ensure the validity of our results for each individual embryo. Compared with bisulphite sequencing methods, the method described is rapid, inexpensive, and relatively high-throughput. PMID:16761730

  14. Comparative analyses of genotoxicity, oxidative stress and antioxidative defence system under exposure of methyl parathion and hexaconazole in barley (Hordeum vulgare L.).

    PubMed

    Dubey, Pragyan; Mishra, Amit Kumar; Singh, Ashok Kumar

    2015-12-01

    The present study aims to evaluate the comparative effects of methyl parathion and hexaconazole on genotoxicity, oxidative stress, antioxidative defence system and photosynthetic pigments in barley (Hordeum vulgare L. variety karan-16). The seeds were exposed with three different concentrations, i.e. 0.05, 0.1 and 0.5 % for 6 h after three pre-soaking durations 7, 17 and 27 h which represents G1, S and G2 phases of the cell cycle, respectively. Ethyl methane sulphonate, a well-known mutagenic agent and double distilled water, was used as positive and negative controls, respectively. The results indicate significant decrease in mitotic index with increasing concentrations of pesticides, and the extent was higher in methyl parathion. Chromosomal aberrations were found more frequent in methyl parathion than hexaconazole as compared to their respective controls. Treatment with the pesticides induced oxidative stress which was evident with higher contents of H2O2 and lipid peroxidation, and the increase was more prominent in methyl parathion. Contents of total phenolics were increased; however, soluble protein content showed a reverse trend. Among the enzymatic antioxidants, activities of superoxide dismutase and peroxidase were significantly up-regulated, and more increase was noticed in hexaconazole. Increments in total chlorophyll and carotenoid contents were observed up to 0.1 % but decreased at higher concentration (0.5 %), and the reductions were more prominent in methyl parathion than hexaconazole as compared to their respective controls. Methyl parathion treatment caused more damage in the plant cells of barley as compared to hexaconazole, which may be closely related to higher genotoxicity and oxidative stress.

  15. Association of environmental benzo[a]pyrene exposure and DNA methylation alterations in hepatocellular carcinoma: A Chinese case-control study.

    PubMed

    Tian, Meiping; Zhao, Benhua; Zhang, Jie; Martin, Francis L; Huang, Qingyu; Liu, Liangpo; Shen, Heqing

    2016-01-15

    Epidemiological studies implicate environmental risk factors and epigenetic alterations in the multistage process of hepatocellular carcinoma (HCC) development. However, associations between environmental factors and DNA methylation of tumour suppressor genes (TSGs) in HCC development remain ambiguous. Understanding how possible interactions influence risk may provide insights into the complexity of hepato-carcinogenesis. For this study, blood samples were collected from HCC patients (n=90) and healthy volunteers (n=99) from Xiamen (China) and data for selected environmental risk factors [e.g., benzo[a]pyrene (B[a]P), hepatitis B or C virus (HBV or HCV) infection, smoking and alcohol consumption] were recorded; factors identified as significantly higher (P<0.05) amongst case subjects compared to controls were identified. In order to assess associations for epigenetic alterations and HCC risk factors, serum DNA methylation of TSGs was quantified using high-resolution melting (HRM) analysis. Our results clearly indicate elevated methylation patterns for detoxification gene [glutathione-S-transferase Pi (GSTP)] promoter regions in cases compared to control subjects. Additionally, GSTP promoter hypermethylation and B[a]P diol epoxide-albumin (BPDE-Alb) were positively correlated with HCC incidence. Our epidemiological and in vitro cell model studies indicated that GSTP promoter DNA methylation regulates this gene's expression. Moreover, GSTP also plays an important role in B[a]P detoxification and potential protective role against B[a]P-induced liver cell toxicity and hepato-carcinogenesis.

  16. A PHYSIOLOGICALLY BASED PHARMACOKINETIC/PHARMACODYNAMIC (PBPK/PD) MODEL FOR ESTIMATION OF CUMULATIVE RISK FROM EXPOSURE TO THREE N-METHYL CARBAMATES: CARBARYL, ALDICARB, AND CARBOFURAN

    EPA Science Inventory

    A physiologically-based pharmacokinetic (PBPK) model for a mixture of N-methyl carbamate pesticides was developed based on single chemical models. The model was used to compare urinary metabolite concentrations to levels from National Health and Nutrition Examination Survey (NHA...

  17. Model prediction uncertainty of bromide and pesticides transport in laboratory column

    NASA Astrophysics Data System (ADS)

    Dusek, Jaromir; Dohnal, Michal; Snehota, Michal; Sobotkova, Martina; Ray, Chittaranjan; Vogel, Tomas

    2016-04-01

    Knowledge of transport parameters of reactive solutes such as pesticides is a prerequisite for reliable predictions of their fate and transport in soil porous systems. Water flow and transport of bromide tracer and five pesticides (atrazine, imazaquin, sulfometuron methyl, S-metolachlor, and imidacloprid) through an undisturbed soil column of tropical Oxisol were analyzed using a one-dimensional numerical model. Laboratory column leaching experiment with three flow interruptions was conducted. The applied numerical model is based on Richards' equation for solving water flow and the advection-dispersion equation for solving solute transport. A global optimization method was used to evaluate the model's sensitivity to transport parameters and the uncertainty of model predictions. Within the Monte Carlo modeling framework, multiple forward simulations searching through the parametric space, were executed to describe the observed breakthrough curves. All pesticides were found to be relatively mobile. Experimental data indicated significant non-conservative behavior of bromide tracer. All pesticides, with the exception of imidacloprid, were found less persistent. Three of the five pesticides (atrazine, sulfometuron methyl, and S-metolachlor) were better described by the linear kinetic sorption model, while the breakthrough curves of imazaquin and imidacloprid were more appropriately approximated using nonlinear instantaneous sorption. Sensitivity analysis suggested that the model is most sensitive to sorption distribution coefficient. The prediction limits contained most of the measured points of the experimental breakthrough curves, indicating adequate model concept and model structure for the description of transport processes in the soil column under study.

  18. Femtosecond time-resolved photodissociation dynamics of methyl halide molecules on ultrathin gold films

    PubMed Central

    Vaida, Mihai E; Tchitnga, Robert

    2011-01-01

    Summary The photodissociation of small organic molecules, namely methyl iodide, methyl bromide, and methyl chloride, adsorbed on a metal surface was investigated in real time by means of femtosecond-laser pump–probe mass spectrometry. A weakly interacting gold surface was employed as substrate because the intact adsorption of the methyl halide molecules was desired prior to photoexcitation. The gold surface was prepared as an ultrathin film on Mo(100). The molecular adsorption behavior was characterized by coverage dependent temperature programmed desorption spectroscopy. Submonolayer preparations were irradiated with UV light of 266 nm wavelength and the subsequently emerging methyl fragments were probed by photoionization and mass spectrometric detection. A strong dependence of the excitation mechanism and the light-induced dynamics on the type of molecule was observed. Possible photoexcitation mechanisms included direct photoexcitation to the dissociative A-band of the methyl halide molecules as well as the attachment of surface-emitted electrons with transient negative ion formation and subsequent molecular fragmentation. Both reaction pathways were energetically possible in the case of methyl iodide, yet, no methyl fragments were observed. As a likely explanation, the rapid quenching of the excited states prior to fragmentation is proposed. This quenching mechanism could be prevented by modification of the gold surface through pre-adsorption of iodine atoms. In contrast, the A-band of methyl bromide was not energetically directly accessible through 266 nm excitation. Nevertheless, the one-photon-induced dissociation was observed in the case of methyl bromide. This was interpreted as being due to a considerable energetic down-shift of the electronic A-band states of methyl bromide by about 1.5 eV through interaction with the gold substrate. Finally, for methyl chloride no photofragmentation could be detected at all. PMID:22003467

  19. Methyl Halide Production by Periphyton Mats from the Florida Everglades

    NASA Astrophysics Data System (ADS)

    Raffel, A.; Jones, R. D.; Rice, A. L.; Scully, N. M.

    2012-12-01

    Methyl chloride and methyl bromide are trace gases with both natural and anthropogenic origins. Once generated these gases transport chlorine and bromine into the stratosphere, where they play an important role in atmospheric chemistry by participating in ozone depleting catalytic cycles. Coastal wetlands are one location where methyl halide emissions have been proposed to be elevated due to high primary production and ionic halogens. This region also provides a unique study environment due to salt water intrusions which occur during storm or low marsh water level-high tide events. The purpose of this research was to determine how varying concentrations of salinity affect methyl halide production originating from periphyton mats within the Florida Everglades. Florida Everglades periphyton (25 g/L) were exposed to continuous 12 hour dark/light cycles in varying concentrations of salt water (0, 0.1, 1.0, and 10‰). All water samples were analyzed to determine the concentration and production rate of methyl chloride and methyl bromide in periphyton samples using a gas chromatograph coupled with an electron capture detector. The concentration of methyl chloride increased by approximately 3.4 and 60 pM over a 0 to 72 hour range for 1‰ and 10 ‰ treatments respectively, and reached a steady state concentration after 24 hours. There was no significant production of methyl bromide for all treatments. These studies will be used to gain a better understanding of methyl halide production from periphyton mats in simulated natural conditions. This research was supported by the National Science Foundation Chemical Oceanography Program Award No. 1029710.

  20. Role of DNA methylation in the adaptive responses induced in a human B lymphoblast cell line by long-term low-dose exposures to γ-rays and cadmium.

    PubMed

    Ye, Shuang; Yuan, Dexiao; Xie, Yuexia; Pan, Yan; Shao, Chunlin

    2014-10-01

    The possible involvement of epigenetic factors in health risks due to exposures to environmental toxicants and ionizing radiation is poorly understood. We have tested the hypothesis that DNA methylation contributes to the adaptive response (AR) to ionizing radiation or Cd. Human B lymphoblast cells HMy2.CIR were irradiated (0.032 Gy γ-rays) three times per week for 4 weeks or exposed to CdCl2 (0.005, 0.01, or 0.1 μM) for 3 months, and then challenged with a high dose of Cd (50 or 100 μM) or γ-rays (2 Gy). Long-term low-dose radiation (LDR) or long-term low-dose Cd exposure induced AR against challenging doses of Cd and irradiation, respectively. When the primed cells were treated with 5-aza-2'-deoxycytidine (5-aza-dC), a DNA methyltransferase inhibitor, the ARs were eliminated. These results indicate that DNA methylation is involved in the induction of AR in HMy2.CIR cells.

  1. Single ion dynamics in molten sodium bromide

    SciTech Connect

    Alcaraz, O.; Trullas, J.; Demmel, F.

    2014-12-28

    We present a study on the single ion dynamics in the molten alkali halide NaBr. Quasielastic neutron scattering was employed to extract the self-diffusion coefficient of the sodium ions at three temperatures. Molecular dynamics simulations using rigid and polarizable ion models have been performed in parallel to extract the sodium and bromide single dynamics and ionic conductivities. Two methods have been employed to derive the ion diffusion, calculating the mean squared displacements and the velocity autocorrelation functions, as well as analysing the increase of the line widths of the self-dynamic structure factors. The sodium diffusion coefficients show a remarkable good agreement between experiment and simulation utilising the polarisable potential.

  2. Indirect spectrophotometric determination of traces of bromide in water

    USGS Publications Warehouse

    Fishman, M. J.; Skougstad, M.W.

    1963-01-01

    A rapid, accurate, and sensitive indirect spectrophotometric method for the determination of bromide in natural waters is based on the catalytic effect of bromide on the oxidation of iodine to iodate by potassium permanganate in sulfuric acid solution. The method is applicable to concentrations ranging from 1 to 100 ??g. of bromide per liter, but may be modified to extend the concentration range. Most ions commonly occurring in water do not interfere. The standard deviation is 2.9 at bromide concentrations of 100 ??g. per liter and less at lower concentrations. The determination of bromide in samples containing known added amounts gave values ranging from 99 to 105% of the concentration calculated to be present.

  3. Tests of the pesticide root zone model and the aggregate model for transport and transformation of aldicarb, metolachlor, and bromide

    SciTech Connect

    Parrish, R.S.; Smith, C.N.; Fong, F.K.

    1992-01-01

    Mathematical models are widely used to predict leaching of pesticides and nutrients in agricultural systems. The work was conducted to investigate the predictive capability of the Pesticide Root Zone Model (PRZM) and the Aggregate Model (AGGR) for the pesticides aldicarb (2-methyl-2-(methylthio)propionaldehyde-O-(methyl-carbamoyl)oxime), metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide) and for a bromide tracer. Model predictions were compared with data collected from 1984 to 1987 in the Dougherty Plain area of southwestern Georgia. Field data were used to estimate mean concentrations of pesticide and bromide residues in the soil profile on various dates after application in each of four growing seasons. Both models tended to predict rates of movement of bromide tracer compounds in excess of that observed. For metolachlor, a pesticide with a soprption-partition coefficient that is higher than for other compounds in the study, both models provided reasonably accurate predictions within the upper 30-cm zone. For the pesticide aldicarb, results were more variable.

  4. Polarization effects in thallium bromide x-ray detectors

    SciTech Connect

    Kozorezov, A.; Wigmore, J. K.; Gostilo, V.; Shorohov, M.; Owens, A.; Quarati, F.; Webb, M. A.

    2010-09-15

    We present the results of a detailed experimental study of polarization effects in thallium bromide planar x-ray detectors. Measurements were carried out in the range 10-100 keV by scanning a highly focused x-ray beam, 50 {mu}m in diameter, from a synchrotron source across the detector. Above a certain radiation threshold the detector response showed a systematic degradation of its spectroscopic characteristics, peak channel position, peak height, and energy resolution. Using a pump-and-probe technique, we studied the dynamics of spectral degradation, the spatial extent and relaxation of the polarized region, and the dependence of the detector response on bias voltage and temperature. For comparison, we modeled polarization effects induced by the charging of traps by both electrons and holes using a model based on recent theoretical work of Bale and Szeles. We calculated the charge collection efficiency and spectral line shapes as functions of exposure time, beam position, count rate, and photon energy, and obtained credible agreement with experimental results.

  5. Irrigation, organic matter addition, and tarping as methods of reducing emissions of methyl iodide from agricultural soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl iodide (MeI) is set to become increasingly used as a highly effective alternative to the soil fumigant methyl bromide. Due to its physical properties, its emission from soil to air is likely to be high and may become a human health risk. Using soil columns that make it possible to determine e...

  6. Subsurface Ectomycorrhizal Fungi: A New Source of Atmospheric Methyl Halides?

    NASA Astrophysics Data System (ADS)

    Treseder, K. K.; Redeker, K. R.; Allen, M. F.

    2001-12-01

    Incomplete source budgets for methyl halides---compounds that release inorganic halogen radicals which, in turn, catalyze atmospheric ozone depletion---limit our abilities to predict the fate of the stratospheric ozone layer. We tested the ability ectomycorrhizal fungi to produce methyl bromide and methyl iodide. These fungi are abundant in temperate forests, where they colonize tree roots and provide nutrients to their symbiotic plants in exchange for carbon compounds. The observed range of emissions from seven different species in culture is 0.001- to 100-μ g g-1 fungi d-1 for methyl bromide, and 0.5- to 500-μ g g-1 fungi d-1 for methyl iodide. While methyl chloride was not specifically tested, large emissions were observed from several species with little to no emissions observed from others. Further analyses of the effects of substrate concentration, headspace concentration, and temperature were performed on the species Cenococcum geophilum, one of the most abundant ectomycorrhizal fungi. Our results suggest that subsurface fungal emissions may be a significant global source of methyl halides.

  7. DNA Methylation

    PubMed Central

    Marinus, M.G.; Løbner-Olesen, A.

    2014-01-01

    The DNA of E. coli contains 19,120 6-methyladenines and 12,045 5-methylcytosines in addition to the four regular bases and these are formed by the postreplicative action of three DNA methyltransferases. The majority of the methylated bases are formed by the Dam and Dcm methyltransferases encoded by the dam (DNA adenine methyltransferase) and dcm (DNA cytosine methyltransferase) genes. Although not essential, Dam methylation is important for strand discrimination during repair of replication errors, controlling the frequency of initiation of chromosome replication at oriC, and regulation of transcription initiation at promoters containing GATC sequences. In contrast, there is no known function for Dcm methylation although Dcm recognition sites constitute sequence motifs for Very Short Patch repair of T/G base mismatches. In certain bacteria (e.g., Vibrio cholerae, Caulobacter crescentus) adenine methylation is essential and in C. crescentus, it is important for temporal gene expression which, in turn, is required for coordinating chromosome initiation, replication and division. In practical terms, Dam and Dcm methylation can inhibit restriction enzyme cleavage; decrease transformation frequency in certain bacteria; decrease the stability of short direct repeats; are necessary for site-directed mutagenesis; and to probe eukaryotic structure and function. PMID:26442938

  8. Selective oxidation of bromide in wastewater brines from hydraulic fracturing.

    PubMed

    Sun, Mei; Lowry, Gregory V; Gregory, Kelvin B

    2013-07-01

    Brines generated from oil and natural gas production, including flowback water and produced water from hydraulic fracturing of shale gas, may contain elevated concentrations of bromide (~1 g/L). Bromide is a broad concern due to the potential for forming brominated disinfection byproducts (DBPs) during drinking water treatment. Conventional treatment processes for bromide removal is costly and not specific. Selective bromide removal is technically challenging due to the presence of other ions in the brine, especially chloride as high as 30-200 g/L. This study evaluates the ability of solid graphite electrodes to selectively oxidize bromide to bromine in flowback water and produced water from a shale gas operation in Southwestern PA. The bromine can then be outgassed from the solution and recovered, as a process well understood in the bromine industry. This study revealed that bromide may be selectively and rapidly removed from oil and gas brines (~10 h(-1) m(-2) for produced water and ~60 h(-1) m(-2) for flowback water). The electrolysis occurs with a current efficiency between 60 and 90%, and the estimated energy cost is ~6 kJ/g Br. These data are similar to those for the chlor-alkali process that is commonly used for chlorine gas and sodium hydroxide production. The results demonstrate that bromide may be selectively removed from oil and gas brines to create an opportunity for environmental protection and resource recovery.

  9. ARSENIC (+3 OXIDATION STATE) METHYLTRANSFERASE AND THE INORGANIC ARSENIC METHYLATION PHENOTYPE

    EPA Science Inventory

    Inorganic arsenic is enzymatically methylated; hence, its ingestion results in exposure to the parent compound and various methylated arsenicals. Both experimental and epidemiological evidence suggest that some of the adverse health effects associated with chronic exposure to in...

  10. In utero exposure of mice to diesel exhaust particles affects spatial learning and memory with reduced N-methyl-D-aspartate receptor expression in the hippocampus of male offspring.

    PubMed

    Yokota, Satoshi; Sato, Akira; Umezawa, Masakazu; Oshio, Shigeru; Takeda, Ken

    2015-09-01

    Diesel exhaust consists of diesel exhaust particles (DEPs) and gaseous compounds. Previous studies reported that in utero exposure to diesel exhaust affects the central nervous system. However, there was no clear evidence that these effects were caused by diesel exhaust particles themselves, gaseous compounds, or both. Here, we explored the effects of in utero exposure to DEPs on learning and memory in male ICR mice. DEP solutions were administered subcutaneously to pregnant ICR mice at a dose of 0 or 200 μg/kg body weight on gestation days 6, 9, 12, 15, and 18. We examined learning and memory in 9-to-10-week-old male offspring using the Morris water maze test and passive avoidance test. Immediately after the behavioral tests, hippocampi were isolated. Hippocampal N-methyl-D-aspartate receptor (NR) expression was also measured by quantitative RT-PCR analysis. Mice exposed to DEPs in utero showed deficits in the Morris water maze test, but their performance was not significantly different from that of control mice in the passive avoidance test. In addition, DEP-exposed mice exhibited decreased hippocampal NR2A expression. The present results indicate that maternal DEP exposure disrupts learning and memory in male offspring, which is associated with reduced hippocampal NR2A expression.

  11. Efficiency of Ipratropium Bromide and Albuterol Deposition in the Lung Delivered via a Soft Mist Inhaler or Chlorofluorocarbon Metered-Dose Inhaler.

    PubMed

    MacGregor, T R; ZuWallack, R; Rubano, V; Castles, M A; Dewberry, H; Ghafouri, M; Wood, C C

    2016-04-01

    The propellant-free Combivent Respimat Soft Mist Inhaler (CVT-R) was developed to replace the chlorofluorocarbon-propelled Combivent metered-dose inhaler (CVT-MDI). This steady-state pharmacokinetic (PK) substudy evaluated drug lung-delivery efficiency, using data from two phase III safety and efficacy trials. PK parameters were obtained from well-controlled population PK analyses. Area under the plasma concentration-time curve (AUC), maximum observed plasma concentration (C(max)), and minimum observed plasma concentration (C(min)) showed systemic exposure to ipratropium bromide and albuterol delivered via the CVT-R was proportional to ex-mouthpiece delivered dose. Although the labeled dose of ipratropium bromide in the CVT-R was half that in the CVT-MDI, the systemic exposure was comparable. No PK interaction for the ipratropium bromide and albuterol Respimat drug components was demonstrated. Ipratropium bromide alone resulted in similar exposure to the combination of ipratropium bromide and albuterol. These results show that CVT-R delivers drug more efficiently to the lung than CVT-MDI. PMID:26945929

  12. Efficiency of Ipratropium Bromide and Albuterol Deposition in the Lung Delivered via a Soft Mist Inhaler or Chlorofluorocarbon Metered-Dose Inhaler.

    PubMed

    MacGregor, T R; ZuWallack, R; Rubano, V; Castles, M A; Dewberry, H; Ghafouri, M; Wood, C C

    2016-04-01

    The propellant-free Combivent Respimat Soft Mist Inhaler (CVT-R) was developed to replace the chlorofluorocarbon-propelled Combivent metered-dose inhaler (CVT-MDI). This steady-state pharmacokinetic (PK) substudy evaluated drug lung-delivery efficiency, using data from two phase III safety and efficacy trials. PK parameters were obtained from well-controlled population PK analyses. Area under the plasma concentration-time curve (AUC), maximum observed plasma concentration (C(max)), and minimum observed plasma concentration (C(min)) showed systemic exposure to ipratropium bromide and albuterol delivered via the CVT-R was proportional to ex-mouthpiece delivered dose. Although the labeled dose of ipratropium bromide in the CVT-R was half that in the CVT-MDI, the systemic exposure was comparable. No PK interaction for the ipratropium bromide and albuterol Respimat drug components was demonstrated. Ipratropium bromide alone resulted in similar exposure to the combination of ipratropium bromide and albuterol. These results show that CVT-R delivers drug more efficiently to the lung than CVT-MDI.

  13. 4-N,N-Dimethylaminopyridine promoted selective oxidation of methyl aromatics with molecular oxygen.

    PubMed

    Zhang, Zhan; Gao, Jin; Wang, Feng; Xu, Jie

    2012-03-30

    4-N,N-Dimethylaminopyridine (DMAP) as catalyst in combination with benzyl bromide was developed for the selective oxidation of methyl aromatics. DMAP exhibited higher catalytic activity than other pyridine analogues, such as 4-carboxypyridine, 4-cyanopyridine and pyridine. The sp3 hybrid carbon-hydrogen (C-H) bonds of different methyl aromatics were successfully oxygenated with molecular oxygen. The real catalyst is due to the formation of a pyridine onium salt from the bromide and DMAP. The onium salt was well characterized by NMR and the reaction mechanism was discussed.

  14. Chloride, bromide and iodide scintillators with europium

    DOEpatents

    Zhuravleva, Mariya; Yang, Kan

    2016-09-27

    A halide scintillator material is disclosed where the halide may comprise chloride, bromide or iodide. The material is single-crystalline and has a composition of the general formula ABX.sub.3 where A is an alkali, B is an alkali earth and X is a halide which general composition was investigated. In particular, crystals of the formula ACa.sub.1-yEu.sub.yI.sub.3 where A=K, Rb and Cs were formed as well as crystals of the formula CsA.sub.1-yEu.sub.yX.sub.3 (where A=Ca, Sr, Ba, or a combination thereof and X=Cl, Br or I or a combination thereof) with divalent Europium doping where 0.ltoreq.y.ltoreq.1, and more particularly Eu doping has been studied at one to ten mol %. The disclosed scintillator materials are suitable for making scintillation detectors used in applications such as medical imaging and homeland security.

  15. Methyl chloride

    Integrated Risk Information System (IRIS)

    Methyl chloride ; CASRN 74 - 87 - 3 ( 07 / 17 / 2001 ) Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for

  16. Methyl acrylate

    Integrated Risk Information System (IRIS)

    Methyl acrylate ; CASRN 96 - 33 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  17. Methyl chlorocarbonate

    Integrated Risk Information System (IRIS)

    Methyl chlorocarbonate ; CASRN 79 - 22 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinog

  18. Methyl isocyanate

    Integrated Risk Information System (IRIS)

    Methyl isocyanate ; CASRN 624 - 83 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  19. Methyl parathion

    Integrated Risk Information System (IRIS)

    Methyl parathion ; CASRN 298 - 00 - 0 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  20. Methyl methacrylate

    Integrated Risk Information System (IRIS)

    Methyl methacrylate ; CASRN 80 - 62 - 6 ( 03 / 02 / 98 ) Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments f

  1. Methyl iodide

    Integrated Risk Information System (IRIS)

    Methyl iodide ; CASRN 74 - 88 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effe

  2. Evaluation of bromide mass discharge in a sandy aquifer at Vandenberg AFB, CA

    NASA Astrophysics Data System (ADS)

    Mackay, D. M.; Rasa, E.; Einarson, M.; Kaiser, P.; Chakraborty, I.; Scow, K. M.

    2009-12-01

    Side-by-side experiments were conducted by UC Davis research team at a former fuel station at Vandenberg Air Force Base (AFB) to evaluate the rate of transformation of methyl tert-butyl ether (MTBE) to tert-butyl alcohol (TBA) impacted by ethanol and to investigate evidence of TBA degradation under sulfate reducing conditions. On one side we injected groundwater amended with ethanol and MTBE. In the other lane we injected groundwater amended with TBA. On both sides, injected ground water was spiked with bromide tracer to provide estimates of groundwater flow direction variations, flow velocity, dispersion, and mobile mass loss resulting from diffusive sequestration into aquitards. 162 monitoring wells were aligned into seven transects located downgradient of the injection wells. The mass discharge approach was used to evaluate the natural attenuation of the injected constituents. In this talk we will focus on calculations of mass discharge of the bromide tracer at each of the seven monitoring well transects. The amount of bromide mass discharged through each transect was calculated for any sampling time using field measurements of break through curves. Cumulative mass discharges were estimated and, by iteration based on mass balance, the flow properties of the aquifer were estimated. The calibration process resulted in subtle but quantitatively important changes in our assumptions regarding key physical properties of the aquifer (thickness, porosity) which could be only approximately estimated by standard methods (coring, CPT, etc.). On the basis of this calibration, a more robust approach was devised for evaluating the source and fate of TBA in the aquifer.

  3. Structure, function and carcinogenicity of metabolites of methylated and non-methylated polycyclic aromatic hydrocarbons: a comprehensive review.

    PubMed

    Flesher, James W; Lehner, Andreas F

    2016-01-01

    The Unified Theory of PAH Carcinogenicity accommodates the activities of methylated and non-methylated polycyclic aromatic hydrocarbons (PAHs) and states that substitution of methyl groups on meso-methyl substituted PAHs with hydroxy, acetoxy, chloride, bromide or sulfuric acid ester groups imparts potent cancer producing properties. It incorporates specific predictions from past researchers on the mechanism of carcinogenesis by methyl-substituted hydrocarbons, including (1) requirement for metabolism to an ArCH2X type structure where X is a good leaving group and (2) biological substitution of a meso-methyl group at the most reactive center in non-methylated hydrocarbons. The Theory incorporates strong inferences of Fieser: (1) The mechanism of carcinogenesis involves a specific metabolic substitution of a hydrocarbon at its most reactive center and (2) Metabolic elimination of a carcinogen is a detoxifying process competitive with that of carcinogenesis and occurring by a different mechanism. According to this outlook, chemical or biochemical substitution of a methyl group at the reactive meso-position of non-methylated hydrocarbons is the first step in the mechanism of carcinogenesis for most, if not all, PAHs and the most potent metabolites of PAHs are to be found among the meso methyl-substituted hydrocarbons. Some PAHs and their known or potential metabolites and closely related compounds have been tested in rats for production of sarcomas at the site of subcutaneous injection and the results strongly support the specific predictions of the Unified Theory. PMID:26894797

  4. Surface and bulk properties of aqueous decyltrimethylammonium bromide-hexadecyltrimethylammonium bromide mixed system.

    PubMed

    Rodríguez, J L; Sierra, M B; Messina, P V; Morini, M A; Schulz, P C; Del Burgo, P; Junquera, E; Rodríguez, A; Aicart, E

    2007-10-15

    The aqueous mixed system decyltrimethylammonium bromide (C(10)TAB)-hexadecyltrimethylammonium bromide (C(16)TAB) was studied by conductivity, ion-selective electrodes, surface tension, and fluorescence spectroscopy techniques. The mixture critical micelle concentration, cmc(*), aggregation number, N( *), and micelle molar conductivity, Lambda(M)(cmc), showed that the system aggregation is strongly nonideal. Both cmc(*) and N( *) results were analyzed with two different procedures: (i) the regular solution theory on mixed micelles or Rubingh's theory, and (ii) by the determination of the partial critical micelle concentration of the amphiphile component i in the presence of a constant concentration of the other amphiphile component, cmc(i)( *). The Rubingh procedure gives micelles richer in C(16)TAB than the overall mixtures, while procedure (ii) gives micelles having the same composition as in the complete surfactant mixture (alpha(C(10)TAB). Mixed micelles are larger than pure surfactant ones, with nonspherical shape. Using a literature model, the cause of the synergistic effect seems to be a reduction of the hydrocarbon/water contact at the micelle surface when mixed micelles form. Conductivity and ion-selective electrodes indicate that highly ionized premicelles form immediately before the cmc(*). The air/solution interface is strongly nonideal and much richer in C(16)TAB than the composition in the bulk. When micelles form there is a strong desorption from the air/solution interface because micelles are energetically favored when compared with the monolayer.

  5. Effect of cation asymmetry on the aggregation in aqueous 1-alkyl,3-decylimidazolium bromide solutions: molecular dynamics studies.

    PubMed

    Palchowdhury, Sourav; Bhargava, B L

    2014-06-12

    Self-assembly of cations in aqueous solutions of 1-alkyl,3-decylimidazolium bromide (with four different alkyl chains, methyl, butyl, heptyl, and decyl chain,) have been studied using atomistic molecular dynamics simulations. Polydisperse aggregates of cations are formed in the solution with alkyl tails in the core and the polar head groups present at the surface of the aggregates. The shape of the aggregates is dictated by the length of the alkyl chain. Aggregation numbers increase steadily with the increasing alkyl chain length. The greater asymmetry in the two-substituent chain length leads to a different surface structure compared to that of the cations with alkyl chains of similar length.

  6. Carbon nanotubes as an efficient hole collector for high voltage methylammonium lead bromide perovskite solar cells.

    PubMed

    Li, Zhen; Boix, Pablo P; Xing, Guichuan; Fu, Kunwu; Kulkarni, Sneha A; Batabyal, Sudip K; Xu, Wenjing; Cao, Anyuan; Sum, Tze Chien; Mathews, Nripan; Wong, Lydia Helena

    2016-03-28

    A high open circuit voltage (V(OC)) close to 1.4 V under AM 1.5, 100 mW cm(-2) conditions is achieved when carbon nanotubes (CNTs) are used as a hole conductor in methyl ammonium lead bromide (MAPbBr3) perovskite solar cells. Time-resolved photoluminescence and impedance spectroscopy investigations suggest that the observed high V(OC) is a result of the better charge extraction and lower recombination of the CNT hole conductor. Tandem solar cells with all perovskite absorbers are demonstrated with a MAPbBr3/CNT top cell and a MAPbI3 bottom cell, achieving a V(OC) of 2.24 V in series connection. The semitransparent and high voltage MAPbBr3/CNT solar cells show great potential for applications in solar cell windows, tandem solar cells and solar driven water splitting.

  7. Predicting bromide incorporation in a chlorinated indoor swimming pool.

    PubMed

    Chowdhury, Shakhawat; Mazumder, Abu Jafar; Husain, Tahir

    2016-06-01

    The water in and air above swimming pools often contain high levels of disinfection byproducts (DBPs) due to chemical reactions between chlorine- or bromine-based disinfectants and organic/inorganic matter in the source water and released from swimmers. Exposure to these DBPs, though inevitable, can pose health threats to humans. In this study, DBPs in tap water (S1), and water from a chlorinated indoor swimming pool before (S2) and after swimming (S3) were measured. The brominated species constituted the majority of DBPs formed in S1, S2, and S3. Trihalomethanes (THMs) in S3 was 6.9 (range 2.9-11.1) and 1.4 (range 0.52-2.9) times those in S1 and S2, respectively; and the haloacetic acids (HAAs) in S3 was 4.2 (range 2.5-7.5) and 1.2 (range 0.6-2.6) times those in S1 and S2, respectively. The mean THMs in air above the swimming pool before (S2-A) and after swimming (S3-A) were 72.2 and 93.0 μg/m(3), respectively, and their ranges were 36.3-105.8 and 44.1-133.6 μg/m(3), respectively. The average percentages of bromide incorporation (BI) into THMs in S1, S2, and S3 were 3.0, 9.3, and 10.6 %, respectively; and the BI into HAAs in S1, S2, and S3 were 6.6, 12.0, and 12.2 %, respectively. Several models were trained for predicting the BI into THMs and HAAs. The results indicate that additional information is required to develop predictive models for BI in swimming pools.

  8. Nucleophilic substitution rates and solubilities for methyl halides in seawater

    SciTech Connect

    Elliott, S. ); Rowland, S. )

    1993-06-07

    With the present rules limiting the usage of long lived chlorofluorocarbon compounds because of their cumulative impact on ozone depletion in place, emphasis has shifted to studying other compounds which are known to deplete ozone, but also to have much shorter lifetimes. Methyl bromide is one such compound. It is highly reactive with ozone, but is known to have an atmospheric lifetime less than 2 years. Little is known about sources and sinks for this compound, in particular in the oceans. In some ocean areas surface levels are known to be saturated. This paper presents information on some chemical properties of methyl bromide in an oceanographic environment which will be useful in studying the flux of this gas into and out of the oceans, and its dispersal in surface waters.

  9. Delayed adverse effects of neonatal exposure to polymeric nanoparticle poly(ethylene glycol)-block-polylactide methyl ether on hypothalamic-pituitary-ovarian axis development and function in Wistar rats.

    PubMed

    Rollerova, Eva; Jurcovicova, Jana; Mlynarcikova, Alzbeta; Sadlonova, Irina; Bilanicova, Dagmar; Wsolova, Ladislava; Kiss, Alexander; Kovriznych, Jevgenij; Kronek, Juraj; Ciampor, Fedor; Vavra, Ivo; Scsukova, Sona

    2015-11-01

    We studied delayed effects of neonatal exposure to polymeric nanoparticle poly(ethylene glycol)-block-polylactide methyl ether (PEG-b-PLA) on the endpoints related to pubertal development and reproductive function in female Wistar rats from postnatal day 4 (PND4) to PND 176. Female pups were injected intraperitoneally, daily, from PND4 to PND7 with PEG-b-PLA (20 or 40mg/kg b.w.). Both doses of PEG-b-PLA accelerated the onset of vaginal opening compared with the control group. In the low-dose PEG-b-PLA-treated group, a significantly reduced number of regular estrous cycles, increased pituitary weight due to hyperemia, vascular dilatation and congestion, altered course of hypothalamic gonadotropin-releasing hormone-stimulated luteinizing hormone secretion, and increased progesterone serum levels were observed. The obtained data indicate that neonatal exposure to PEG-b-PLA might affect the development and function of hypothalamic-pituitary-ovarian axis (HPO), and thereby alter functions of the reproductive system in adult female rats. Our study indicates a possible neuroendocrine disrupting effect of PEG-b-PLA nanoparticles.

  10. Delayed adverse effects of neonatal exposure to polymeric nanoparticle poly(ethylene glycol)-block-polylactide methyl ether on hypothalamic-pituitary-ovarian axis development and function in Wistar rats.

    PubMed

    Rollerova, Eva; Jurcovicova, Jana; Mlynarcikova, Alzbeta; Sadlonova, Irina; Bilanicova, Dagmar; Wsolova, Ladislava; Kiss, Alexander; Kovriznych, Jevgenij; Kronek, Juraj; Ciampor, Fedor; Vavra, Ivo; Scsukova, Sona

    2015-11-01

    We studied delayed effects of neonatal exposure to polymeric nanoparticle poly(ethylene glycol)-block-polylactide methyl ether (PEG-b-PLA) on the endpoints related to pubertal development and reproductive function in female Wistar rats from postnatal day 4 (PND4) to PND 176. Female pups were injected intraperitoneally, daily, from PND4 to PND7 with PEG-b-PLA (20 or 40mg/kg b.w.). Both doses of PEG-b-PLA accelerated the onset of vaginal opening compared with the control group. In the low-dose PEG-b-PLA-treated group, a significantly reduced number of regular estrous cycles, increased pituitary weight due to hyperemia, vascular dilatation and congestion, altered course of hypothalamic gonadotropin-releasing hormone-stimulated luteinizing hormone secretion, and increased progesterone serum levels were observed. The obtained data indicate that neonatal exposure to PEG-b-PLA might affect the development and function of hypothalamic-pituitary-ovarian axis (HPO), and thereby alter functions of the reproductive system in adult female rats. Our study indicates a possible neuroendocrine disrupting effect of PEG-b-PLA nanoparticles. PMID:26193689

  11. Carbon nanotubes as an efficient hole collector for high voltage methylammonium lead bromide perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Li, Zhen; Boix, Pablo P.; Xing, Guichuan; Fu, Kunwu; Kulkarni, Sneha A.; Batabyal, Sudip K.; Xu, Wenjing; Cao, Anyuan; Sum, Tze Chien; Mathews, Nripan; Wong, Lydia Helena

    2016-03-01

    A high open circuit voltage (VOC) close to 1.4 V under AM 1.5, 100 mW cm-2 conditions is achieved when carbon nanotubes (CNTs) are used as a hole conductor in methyl ammonium lead bromide (MAPbBr3) perovskite solar cells. Time-resolved photoluminescence and impedance spectroscopy investigations suggest that the observed high VOC is a result of the better charge extraction and lower recombination of the CNT hole conductor. Tandem solar cells with all perovskite absorbers are demonstrated with a MAPbBr3/CNT top cell and a MAPbI3 bottom cell, achieving a VOC of 2.24 V in series connection. The semitransparent and high voltage MAPbBr3/CNT solar cells show great potential for applications in solar cell windows, tandem solar cells and solar driven water splitting.A high open circuit voltage (VOC) close to 1.4 V under AM 1.5, 100 mW cm-2 conditions is achieved when carbon nanotubes (CNTs) are used as a hole conductor in methyl ammonium lead bromide (MAPbBr3) perovskite solar cells. Time-resolved photoluminescence and impedance spectroscopy investigations suggest that the observed high VOC is a result of the better charge extraction and lower recombination of the CNT hole conductor. Tandem solar cells with all perovskite absorbers are demonstrated with a MAPbBr3/CNT top cell and a MAPbI3 bottom cell, achieving a VOC of 2.24 V in series connection. The semitransparent and high voltage MAPbBr3/CNT solar cells show great potential for applications in solar cell windows, tandem solar cells and solar driven water splitting. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06177f

  12. Phenotypic and karyotypic changes induced in cultured rat hepatic epithelial cells that express the "oval" cell phenotype by exposure to N-methyl-N'-nitro-N-nitrosoguanidine.

    PubMed Central

    Tsao, M. S.; Grisham, J. W.; Nelson, K. G.; Smith, J. D.

    1985-01-01

    A diploid population of cultured rat hepatic epithelial cells that expresses the "oval" cell phenotype was exposed briefly and repetitively to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), and the effect on more than 20 phenotypic properties was evaluated during the neoplastic transformation of the population. MNNG treatments of this hepatic epithelial cell population resulted in a progressively increasing phenotypic alteration and heterogeneity including changes in specific activities of several cellular enzymes and expression of isozymes, synthetic functions, and various in vitro growth properties. Changes in phenotypic expression were clustered episodically and were associated with major karyotypic changes. The development of increasing phenotypic heterogeneity preceding and accompanying tumorigenicity in cultured liver epithelial cells in vitro and the specific phenotypes that occur resemble superficially the pattern of phenotypic changes that occur in hepatocytes during chemical hepatocarcinogenesis in vivo. The results of this study provide the basis for future investigations to further elucidate the mechanistic and linkage relationship between specific pretumorigenic and paratumorigenic phenotypes and tumorigenicity. Images Figure 3 Figure 9 PMID:3970142

  13. Linkage of the California Pesticide Use Reporting Database with Spatial Land Use Data for Exposure Assessment

    PubMed Central

    Nuckols, John R.; Gunier, Robert B.; Riggs, Philip; Miller, Ryan; Reynolds, Peggy; Ward, Mary H.

    2007-01-01

    Background The State of California maintains a comprehensive Pesticide Use Reporting Database (CPUR). The California Department of Water Resources (CDWR) maps all crops in agricultural counties in California about once every 5 years. Objective We integrated crop maps with CPUR to more accurately locate where pesticides are applied and evaluated the effects for exposure assessment. Methods We mapped 577 residences and used the CPUR and CDWR data to compute two exposure metrics based on putative pesticide use within a 500-m buffer. For the CPUR metric, we assigned pesticide exposure to the residence proportionally for all square-mile Sections that intersected the buffer. For the CDWR metric, we linked CPUR crop-specific pesticide use to crops mapped within the buffer and assigned pesticide exposure. We compared the metrics for six pesticides: simazine, trifluralin (herbicides), dicofol, propargite (insecticides), methyl bromide, and metam sodium (fumigants). Results For all six pesticides we found good agreement (88–98%) as to whether the pesticide use was predicted. When we restricted the analysis to residences with reported pesticide use in Sections within 500 m, agreement was greatly reduced (35–58%). The CPUR metric estimates of pesticide use within 500 m were significantly higher than the CDWR metric for all six pesticides. Conclusions Our findings may have important implications for exposure classification in epidemiologic studies of agricultural pesticide use using CPUR. There is a need to conduct environmental and biological measurements to ascertain which, if any, of these metrics best represent exposure. PMID:17520053

  14. Methyl substituted polyimides containing carbonyl and ether connecting groups

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M. (Inventor); Havens, Stephen J. (Inventor)

    1992-01-01

    Polyimides were prepared from the reaction of aromatic dianhydrides with novel aromatic diamines having carbonyl and ether groups connecting aromatic rings containing pendant methyl groups. The methyl substituent polyimides exhibit good solubility and form tough, strong films. Upon exposure to ultraviolet irradiation and/or heat, the methyl substituted polyimides crosslink to become insoluble.

  15. Methyl Iodide Fumigation of Bacillus anthracis Spores.

    PubMed

    Sutton, Mark; Kane, Staci R; Wollard, Jessica R

    2015-09-01

    Fumigation techniques such as chlorine dioxide, vaporous hydrogen peroxide, and paraformaldehyde previously used to decontaminate items, rooms, and buildings following contamination with Bacillus anthracis spores are often incompatible with materials (e.g., porous surfaces, organics, and metals), causing damage or residue. Alternative fumigation with methyl bromide is subject to U.S. and international restrictions due to its ozone-depleting properties. Methyl iodide, however, does not pose a risk to the ozone layer and has previously been demonstrated as a fumigant for fungi, insects, and nematodes. Until now, methyl iodide has not been evaluated against Bacillus anthracis. Sterne strain Bacillus anthracis spores were subjected to methyl iodide fumigation at room temperature and at 550C. Efficacy was measured on a log-scale with a 6-log reduction in CFUs being considered successful compared to the U.S. Environmental Protection Agency biocide standard. Such efficacies were obtained after just one hour at 55 °C and after 12 hours at room temperature. No detrimental effects were observed on glassware, PTFE O-rings, or stainless steel. This is the first reported efficacy of methyl iodide in the reduction of Bacillus anthracis spore contamination at ambient and elevated temperatures. PMID:26502561

  16. Methyl Iodide Fumigation of Bacillus anthracis Spores.

    PubMed

    Sutton, Mark; Kane, Staci R; Wollard, Jessica R

    2015-09-01

    Fumigation techniques such as chlorine dioxide, vaporous hydrogen peroxide, and paraformaldehyde previously used to decontaminate items, rooms, and buildings following contamination with Bacillus anthracis spores are often incompatible with materials (e.g., porous surfaces, organics, and metals), causing damage or residue. Alternative fumigation with methyl bromide is subject to U.S. and international restrictions due to its ozone-depleting properties. Methyl iodide, however, does not pose a risk to the ozone layer and has previously been demonstrated as a fumigant for fungi, insects, and nematodes. Until now, methyl iodide has not been evaluated against Bacillus anthracis. Sterne strain Bacillus anthracis spores were subjected to methyl iodide fumigation at room temperature and at 550C. Efficacy was measured on a log-scale with a 6-log reduction in CFUs being considered successful compared to the U.S. Environmental Protection Agency biocide standard. Such efficacies were obtained after just one hour at 55 °C and after 12 hours at room temperature. No detrimental effects were observed on glassware, PTFE O-rings, or stainless steel. This is the first reported efficacy of methyl iodide in the reduction of Bacillus anthracis spore contamination at ambient and elevated temperatures.

  17. Bromide therapy in refractory canine idiopathic epilepsy.

    PubMed

    Podell, M; Fenner, W R

    1993-01-01

    On a retrospective basis, the response to adding chronic oral bromide (BR) to phenobarbital (PB) administration in 23 refractory canine idiopathic epileptics between 1986 and 1991 was studied. The mean age for an observed first seizure was 24 months (range 7 to 72) for all dogs. Thirteen (57%) dogs were males with no breed predisposition observed. All dogs were diagnosed as having idiopathic epilepsy based on normal metabolic and neurologic diagnostic evaluations. Dogs were evaluated before BR therapy for a mean time of 22 months (range 5 to 75 months). Seventeen dogs (74%) received multiple antiepileptic drugs (AEDs) before BR therapy. All animals were maintained on PB at least 4 months before the onset of BR therapy, with a mean trough serum concentration of 37.8 mcg/mL and no improvement in seizure severity or recurrence. Twelve dogs presented with generalized isolated seizures and 11 with generalized cluster seizures (two or more seizures within 24 hours) as their first seizure. The effects of BR therapy were evaluated for a mean time of 15 months (range 4 to 33), with 17 dogs (74%) followed for 12 or more months. The mean BR serum concentration for the 0 to 4 months time period was 117 mg/dL compared with 161 mg/dL for the greater than 4 months period. Overall, response to BR therapy was associated with a reduction in the total number of seizures in 83% of the dogs when compared with their respective pre-BR period. For those followed for 1 year after BR, there was a 53% reduction in the number of seizures compared with the previous 12 months. Furthermore, owners reported a decrease in seizure intensity (65% of dogs) and change to a less severe seizure type (22% of dogs) in those dogs that continued to have seizures. Seizure-free status was obtained in 26% of the dogs with protection continuing up to 31 months in one dog. No correlations could be determined between response to BR and either age of onset of the first seizure or interval from the first AED

  18. Two-hour methyl isocyanate inhalation exposure and 91-day recovery: a preliminary description of pathologic changes in F344 rats

    SciTech Connect

    Bucher, J.R.; Boorman, G.A.; Gupta, B.N.; Uraih, L.C.; Hall, L.B.; Stefanski, S.A.

    1987-06-01

    To study the pathology of acute inhalation exposure to MIC, the tissues of male and female Fischer 344 rats were evaluated immediately after a single 2-hr exposure to 0, 3, 10, or 30 ppm MIC, and through day 91. Early gross pathologic changes in the 30 ppm-exposed rats included a reddish white encrustation around the mouth and nose, a small thymus, and distension of the gastrointestinal tract with gas. Lungs (middle and median lobes) showed consolidation and hemorrhage and failed to deflate when the chest cavity was opened. Microscopic changes in the upper respiratory tract 3 hr after exposure included marked erosion and separation of olfactory and respiratory epithelia from the basement membrane with accumulation of serofibrinous fluid. On day 1, acute inflammation and fibrinopurulent exudate partially blocked the nasal passages. Epithelial cells had sloughed from the nasopharynx, trachea, bronchi, and major bronchioles, leaving the basement membrane covered with fibrin and exudate. Granulomatous inflammation and intraluminal fibrosis of the airways were observed with fibrin and exudate. Grandulomatous inflammation and intraluminal fibrosis of the airways were observed by day 3, with increased intraluminal fibrosis by day 7. Lower airways became blocked by exfoliated cells, mucous plugs, and/or intraluminal fibrosis. Damage to the lung parenchyma, even at lethal concentrations, was limited to moderate inflammation. Intraluminal fibrosis, mild bronchitis and bronchiolitis,and mucous plugs persisted throughout 91-day study. These changes could account for evidence of obstructive lung disease detected in pulmonary function studies in companion studies. Evidence of direct injury to nonrespiratory tissues was found.

  19. Inhibition of catechol-O-methyl transferase (COMT) by tolcapone restores reductions in microtubule-associated protein 2 (MAP2) and synaptophysin (SYP) following exposure of neuronal cells to neurotropic HIV.

    PubMed

    Lee, Ting Ting; Chana, Gursharan; Gorry, Paul R; Ellett, Anne; Bousman, Chad A; Churchill, Melissa J; Gray, Lachlan R; Everall, Ian P

    2015-10-01

    This investigation aimed to assess whether inhibition of cathecol-O-methyl transferase (COMT) by tolcapone could provide neuroprotection against HIV-associated neurodegenerative effects. This study was conducted based on a previous work, which showed that a single nucleotide polymorphism (SNP) at position 158 (val158met) in COMT, resulted in 40 % lower COMT activity. Importantly, this reduction confers a protective effect against HIV-associated neurocognitive disorders (HAND), which have been linked to HIV-associated brain changes. SH-SY5Y-differentiated neurons were exposed to macrophage-propagated HIV (neurotropic MACS2-Br strain) in the presence or absence of tolcapone for 6 days. RNA was extracted, and qPCR was performed using Qiagen RT2 custom array consisting of genes for neuronal and synaptic integrity, COMT and pro-inflammatory markers. Immunofluorescence was conducted to validate the gene expression changes at the protein level. Our findings demonstrated that HIV significantly increased the messenger RNA (mRNA) expression of COMT while reducing the expression of microtubule-associated protein 2 (MAP2) (p = 0.0015) and synaptophysin (SYP) (p = 0.012) compared to control. A concomitant exposure of tolcapone ameliorated the perturbed expression of MAP2 (p = 0.009) and COMT (p = 0.024) associated with HIV. Immunofluorescence revealed a trend reduction of SYP and MAP2 with exposure to HIV and that concomitant exposure of tolcapone increased SYP (p = 0.016) compared to HIV alone. Our findings demonstrated in vitro that inhibition of COMT can ameliorate HIV-associated neurodegenerative changes that resulted in the decreased expression of the structural and synaptic components MAP2 and SYP. As HIV-associated dendritic and synaptic damage are contributors to HAND, inhibition of COMT may represent a potential strategy for attenuating or preventing some of the symptoms of HAND.

  20. Effects of temperature on micellar-assisted bimolecular reaction of methylnaphtalene-2-sulphonate with bromide and chloride ions.

    PubMed

    Di Michele, A; Germani, R; Pastori, G; Spreti, N; Brinchi, L

    2013-07-15

    Reactivity of methyl naphthalene-2-sulphonate, MeONs, with H2O, Br(-) and Cl(-) in water and in cationic micelles of cetyltrialkylammonium surfactants, n-C16H33N(+)R3X(-), R=Me (CTA(+)), n-Pr (CTPA(+)), X=Br, Cl, CH3SO3, has been investigated in the temperature range 25-45°C. Micellar rate effects were analysed by using the pseudophase treatment, and the second-order rate constants in the micellar pseudophase were evaluated at the various temperatures. Values of these rate constants increase with temperature, and the effect is less important in micelles than in water and more important for chloride than for bromide ions. Micelles lead to an ion behaviour discrimination, whose extent depends on surfactant type and on temperature, with maximum effect in CTPA(+) at 25°C and with bromide being always more reactive than chloride. Quantitative analysis of the temperature effect by the Eyring equation showed that micelles speed up reaction of MeONs with halide ions by decreasing the activation enthalpies, which is partially offset by decreases in the activation entropies. The rate acceleration by increase in surfactant head group size has only enthalpic origin for bromide and only entropic origin for chloride: this different behaviour was rationalised taking into account both solvation of anions and the hydrophobic effect.

  1. Induction of Memory Deficit in Mice with Chronic Exposure to Cerebrospinal Fluid from Patients with Anti-N-Methyl-D-Aspartate Receptor Encephalitis.

    PubMed

    Li, Yongzhi; Tanaka, Keiko; Wang, Li; Ishigaki, Yasuhito; Kato, Nobuo

    2015-01-01

    Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is now widely recognized and the patients with this disease show prominent psychiatric symptoms followed by seizures, respiratory failure, involuntary movement, autonomic instability, and amnesia. The anti-NMDAR antibody titer coincides with disease activity, and antibody-deprivation treatment ameliorates neurological symptoms. Previous studies have shown that clusters of NMDARs on the neuronal surface decrease in density upon incubation with the cerebrospinal fluid from patients (NMDAR-CSF), and that the induction of long-term potentiation, a cellular mechanism underlie learning and memory processes, was suppressed with NMDAR-CSF. In this study, we exposed mice to NMDAR-CSF in an attempt to reproduce the human symptoms in mice. CSF was continuously administered via a cannula placed in the lateral ventricle of the mouse that connected to an osmotic pump transplanted in the back of the mouse. From day 8-18, we evaluated the behavior of the mice using standardized tests that were performed serially. Mice exposed to NMDAR-CSF showed impaired spatial memory, as detected with the Morris water maze test. Brain tissue from mice with memory disturbances had decreased content of NMDAR protein in the hippocampal area shown by immunohistochemistry, which is consistent with the anti-NMDAR antibodies affect the expression and function of NMDARs, resulting in anti-NMDAR encephalitis-like symptoms. Also, the mice treated with the NMDAR-CSF did not show inflammatory cell infiltration or neuron loss in their brain tissue and this lack of nervous tissue destruction is encouraging as it is consistent with the idea that this disease can be treated through immunotherapy.

  2. Biological effects of short-term, high-concentration exposure to methyl isocyanate. V. Morphologic evaluation of rat and guinea pig lungs

    SciTech Connect

    Fowler, E.H.; Dodd, D.E.; Troup, C.M.

    1987-06-01

    The morphologic changes induced in the lungs of rats and guinea pigs exposed to high concentrations of MIC vapor (100, 600, and 1000 ppm in the rat and 25, 125, 225, and 675 ppm in the guinea pig) for a short time (15 min) in a static exposure chamber were evaluated at varying postexposure periods (0, 1, 2, and 4, and 16 hr). The 675 ppm-exposed guinea pigs were evaluated only immediately following removal from the chamber. Attention was primarily focused on the intrapulmonary conducting airways and the parenchyma (gas exchange region) of the lungs. The severity of morphologic changes observed by light microscopy was directly correlated with exposure concentration and time postexposure in both species. Specifically, degenerative changes were observed in the bronchial, bronchiolar, and alveolar epithelium in both species. Quantitative differences were observed; 100 ppm of MIC in the rat resulted in much less damage than did 125 ppm of MIC in the guinea pig. Morphologic evidence of sloughing of large sheets of conducting airway epithelium with fibrin buildup and increased mucus production resulted in plugging of major airways and atelectasis. These observations support the hypothesis that tissue hypoxia was a major contributing factor resulting in death.

  3. Zinc Bromide Combustion: Implications for the Consolidated Incinerator Facility

    SciTech Connect

    Oji, L.N.

    1998-12-16

    In the nuclear industry, zinc bromide (ZnBr2) is used for radiation shielding. At Savannah River Site (SRS) zinc bromide solution, in appropriate configurations and housings, was used mainly for shielding in viewing windows in nuclear reactor and separation areas. Waste stream feeds that will be incinerated at the CIF will occasionally include zinc bromide solution/gel matrices.The CIF air pollution systems control uses a water-quench and steam atomizer scrubber that collects salts, ash and trace metals in the liquid phase. Water is re-circulated in the quench unit until a predetermined amount of suspended solids or dissolved salts are present. After reaching the threshold limit, "dirty liquid", also called "blowdown", is pumped to a storage tank in preparation for treatment and disposal. The air pollution control system is coupled to a HEPA pre-filter/filter unit, which removes particulate matter from the flue gas stream (1).The objective of this report is to review existing literature data on the stability of zinc bromide (ZnBr2) at CIF operating temperatures (>870 degrees C (1600 degrees F) and determine what the combustion products are in the presence of excess air. The partitioning of the combustion products among the quencher/scrubber solution, bottom ash and stack will also be evaluated. In this report, side reactions between zinc bromide and its combustion products with fuel oil were not taken into consideration.

  4. Electrophysiological study of intravenous pinaverium bromide in cardiology.

    PubMed

    Guerot, C; Khemache, A; Sebbah, J; Noel, B

    1988-01-01

    Pinaverium bromide is a musculotropic spasmolytic agent which acts by inhibiting transmembrane calcium movements, an effect similar to that of verapamil. Because of this, an investigation was carried out to see if it had any electrophysiological effects in patients with various cardiac disorders. In an open study, 10 patients received 2 mg pinaverium bromide intravenously. In a double-blind study, 10 patients received 4 mg pinaverium bromide intravenously and 10 patients placebo. Patients included those with either normal or pathological basal conduction, such as bundle-branch block and 1st degree atrioventricular block. Measurements were made of electrophysiological parameters before and 10 minutes after injection. The results showed that neither of the two doses of pinaverium bromide had any effect on atrial excitability, sino-atrial conduction, node and trunk atrioventricular conduction or on intraventricular conduction. No significant difference was seen in comparison with placebo. Pinaverium bromide had no anti-arrhythmic properties in these studies. Local, cardiac and general clinical tolerability was good in all patients. PMID:3219882

  5. Does bromide cause conversion of epilepsy to psychosis?

    PubMed

    Lund, M

    1997-04-01

    The aim of this study is to find out whether bromide was able to cause conversion of epilepsy to psychosis i.e., so-called paradoxical normalization such as has been seen in treatment with modern antiepileptic drugs. Spontaneous conversion has been known for three hundred years. Locock introduced bromide in the treatment of epilepsy in 1857. Belgrave wrote in 1868 on its effect on epileptic attacks and concommitant insanity. In 1868 Holm observed reduction of the frequency of seizures at the same time as psychotic symptoms or just dysphoria. In 1875 Voisin described a dose-dependent intoxication with psychosis and/or neurological signs. Stark in 1875 and Bannister in 1881 were the first to clearly describe the antagonism between epileptic seizures and psychotic symptoms, an antagonism or conversion described by many authors, both in cases with high and low dosage, and with and without intoxication. Thus, the title of this paper should be answered in the affirmative. Bromide has been used as a sedative and has rarely caused intoxication. Thus the presence of epilepsy is not a condition for the development of bromide intoxication. A case with epilepsy and fatal massive bromide intoxication is reported. It is discussed whether the pathological findings give support to Wolf's hypothesis of latent epileptic activity in subcortical pathways during "normalization".

  6. Effect of Bromide-Hypochlorite Bactericides on Microorganisms1

    PubMed Central

    Shere, Lewis; Kelley, Maurice J.; Richardson, J. Harold

    1962-01-01

    A new principle in compounding stable, granular bactericidal products led to unique combinations of a water-soluble inorganic bromide salt with a hypochlorite-type disinfectant of either inorganic or organic type. Microbiological results are shown for an inorganic bactericide composed of chlorinated trisodium phosphate containing 3.1% “available chlorine” and 2% potassium bromide, and for an organic bactericide formulated from sodium dichloroisocyanurate so as to contain 13.4% “available chlorine” and 8% potassium bromide. Comparison of these products with their nonbromide counterparts are reported for Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Streptococcus lactis, Aerobacter aerogenes, and Proteus vulgaris. Test methods employed were the Chambers test, the A.O.A.C. Germicidal and Detergent Sanitizer-Official test, and the Available Chlorine Germicidal Equivalent Concentration test. The minimal killing concentrations for the bromide-hypochlorite bactericides against this variety of organisms were reduced by a factor 2 to 24 times those required for similar hypochlorite-type disinfectants not containing the bromide. PMID:13977149

  7. Large methyl halide emissions from south Texas salt marshes

    NASA Astrophysics Data System (ADS)

    Rhew, R. C.; Whelan, M. E.; Min, D.-H.

    2014-06-01

    Coastal salt marshes are natural sources of methyl chloride (CH3Cl) and methyl bromide (CH3Br) to the atmosphere, but measured emission rates vary widely by geography. Here we report large methyl halide fluxes from subtropical salt marshes of south Texas. Sites with the halophytic plant, Batis maritima, emitted methyl halides at rates that are orders of magnitude greater than sites containing other vascular plants or macroalgae. B. maritima emissions were generally highest at midday; however, diurnal variability was more pronounced for CH3Br than CH3Cl, and surprisingly high nighttime CH3Cl fluxes were observed in July. Seasonal and intra-site variability were large, even taking into account biomass differences. Overall, these subtropical salt marsh sites show much higher emission rates than temperate salt marshes at similar times of the year, supporting the contention that low-latitude salt marshes are significant sources of CH3Cl and CH3Br.

  8. Large methyl halide emissions from south Texas salt marshes

    NASA Astrophysics Data System (ADS)

    Rhew, R. C.; Whelan, M. E.; Min, D.-H.

    2014-11-01

    Coastal salt marshes are natural sources of methyl chloride (CH3Cl) and methyl bromide (CH3Br) to the atmosphere, but measured emission rates vary widely by geography. Here we report large methyl halide fluxes from subtropical salt marshes of south Texas. Sites with the halophytic plant, Batis maritima, emitted methyl halides at rates that are orders of magnitude greater than sites containing other vascular plants or macroalgae. B. maritima emissions were generally highest at midday; however, diurnal variability was more pronounced for CH3Br than CH3Cl, and surprisingly high nighttime CH3Cl fluxes were observed in July. Seasonal and intra-site variability were large, even taking into account biomass differences. Overall, these subtropical salt marsh sites show much higher emission rates than temperate salt marshes at similar times of the year, supporting the contention that low-latitude salt marshes are significant sources of CH3Cl and CH3Br.

  9. Biological effects of short-term, high-concentration exposure to methyl isocyanate. VI. In vitro and in vivo complement activation studies

    SciTech Connect

    Kolb, W.P.; Savary, J.R.; Troup, C.M.; Dodd, D.E.; Tamerius, J.D.

    1987-06-01

    The ability of MIC to induce complement activation in vitro and in vivo was investigated. For the in vitro studies, both human and guinea pig serum or EDTA-plasma samples were exposed to 1167 to 1260 ppm MIC vapor for 15 min at room temperature. The human serum samples exposed to MIC showed significant reduction in Factor B, C2, C4, C3, C5, and total hemolytic complement CH/sub 50/ activity levels. The C3, C5, and CH/sub 50/ functional activities in guinea pig serum were more sensitive to MIC-mediated reduction than the corresponding activity reductions observed in the human serum samples. The human and single guinea pig EDTA-plasma samples exposed to MIC vapor showed no evidence of C3 consumption but did show significant reductions in CH/sub 50/ levels. Thus, MIC vapor was able to active, and thereby reduce serum complement C3 activity in vitro by a complement-dependent process. For the in vivo studies, five pairs of guinea pigs were exposed to 644 to 702 ppm MIC vapor until one of the pair died (11-15 min). MIC exposure was then discontinued, the surviving guinea pig was sacrificed, and EDTA-plasma was obtained from both animals and analyzed for complement consumption. Clear evidence was obtained to indicate that complement activation had occurred in these animals exposed to MIC for 11 to 15 min. In addition, the complement activation profile observed in these guinea pigs was qualitatively similar to that seen in the guinea pig serum samples exposed to MIC vapor in vitro. The total protein concentration present in plasma samples obtained from guinea pigs that had died from MIC exposure was elevated significantly. The possible contribution of complement activation to the fatal reaction(s) observed in these MIC-treated animals is discussed.

  10. Influence of Soil fumigation by Methyl Bromide and Methyl Iodide on Rhizosphere and Phyllosphere Microbial Community Structure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rhizosphere and phyllosphere microbial communities were evaluated on roots and leaves of growth chamber-grown lettuce (Lactuca sativa (L.) cv. Green Forest) plants by culture-dependent and -independent methods after soil fumigation. Denaturing gradient gel electrophoresis (DGGE) with 16S rRNA primer...

  11. Impact of bromide on halogen incorporation into organic moieties in chlorinated drinking water treatment and distribution systems.

    PubMed

    Tan, J; Allard, S; Gruchlik, Y; McDonald, S; Joll, C A; Heitz, A

    2016-01-15

    The impact of elevated bromide concentrations (399 to 750 μg/L) on the formation of halogenated disinfection by-products (DBPs), namely trihalomethanes, haloacetic acids, haloacetonitriles, and adsorbable organic halogen (AOX), in two drinking water systems was investigated. Bromine was the main halogen incorporated into all of the DBP classes and into organic carbon, even though chlorine was present in large excess to maintain a disinfectant residual. Due to the higher reactivity of bromine compared to chlorine, brominated DBPs were rapidly formed, followed by a slower increase in chlorinated DBPs. Higher bromine substitution and incorporation factors for individual DBP classes were observed for the chlorinated water from the groundwater source (lower concentration of dissolved organic carbon (DOC)), which contained a higher concentration of bromide, than for the surface water source (higher DOC). The molar distribution of adsorbable organic bromine to chlorine (AOBr/AOCl) for AOX in the groundwater distribution system was 1.5:1 and almost 1:1 for the surface water system. The measured (regulated) DBPs only accounted for 16 to 33% of the total organic halogen, demonstrating that AOX measurements are essential to provide a full understanding of the formation of halogenated DBPs in drinking waters. In addition, the study demonstrated that a significant proportion (up to 94%) of the bromide in source waters can be converted AOBr. An evaluation of AOBr and AOCl through a second groundwater treatment plant that uses conventional treatment processes for DOC removal produced 70% of AOX as AOBr, with 69% of the initial source water bromide converted to AOBr. Exposure to organobromine compounds is suspected to result in greater adverse health consequences than their chlorinated analogues. Therefore, this study highlights the need for improved methods to selectively reduce the bromide content in source waters.

  12. Dissolved humic substances initiate DNA-methylation in cladocerans.

    PubMed

    Menzel, Stefanie; Bouchnak, Rihab; Menzel, Ralph; Steinberg, Christian E W

    2011-10-01

    DNA-methylation is one pathway of epigenetic programming of gene expression and can be responsive to environmental challenges such as methylating agents in the food. Here we report on the DNA-methylation in the cladocerans Daphnia magna and Moina macrocopa exposed to humic substances, ubiquitous biogeochemicals. The methylation of DNA can alter the stress response, presumably including exposure to synthetic xenobiotic chemicals. PMID:21963594

  13. IR, Raman and SERS spectra of propantheline bromide.

    PubMed

    Baraldi, C; Freguglia, G; Tinti, A; Sparta, M; Alexandrova, A N; Gamberini, M C

    2013-02-15

    The two known propantheline bromide polymorphs (form I and form II) were studied and characterized by a multianalytical approach. In the present work, the identification of propantheline bromide polymorphic forms through vibrational IR spectroscopies are presented and for the first time Raman microscopy and hot stage Raman microscopy (HSRM) studies are reported. Finally, quantum mechanical calculations were performed. For assisting the assignment of the experimental picks, the two IR spectra of the most and least stable representatives of a set of 56 conformers are calculated and studied. DSC thermograms data, are also reported. The surface enhanced Raman scattering (SERS) spectrum was also recorded in a silver colloid; it could be inferred that propantheline bromide is adsorbed on silver colloid through the oxygen atom with the molecular plane perpendicular to the metal surface.

  14. Gender differential effects of developmental exposure to methyl-mercury, polychlorinated biphenyls 126 or 153, or its combinations on motor activity and coordination.

    PubMed

    Cauli, Omar; Piedrafita, Blanca; Llansola, Marta; Felipo, Vicente

    2013-09-01

    Polychlorinated biphenyls (PCBs) and methylmercury (MeHg) are persistent organic pollutants accumulating in the food chain. Pre- and neonatal exposure to these neurotoxicants may affect brain development and lead to long-lasting alterations in cerebral function, which can result in motor alterations in youth and/or adulthood. Some neurotoxicants induce gender specific effects. The aims of the present work were to: (1) assess the effects of developmental exposure to MeHg, PCB 153 or PCB 126 on spontaneous locomotor and vertical activity and motor coordination when the rats are 2-month old; (2) assess whether perinatal exposure to combinations of MeHg with PCB153 or PCB126 alter the effects of the individual neurotoxicants; (3) follow the progression of motor alterations when the rats are 3-, 5- and 7-month old; (4) assess if the effects are similar or different in males and females. Pregnant rats were treated with MeHg (0.5mg/kgday); PCB126 (100ng/kgday) or PCB153 (1mg/kgday) or with combinations of MeHg with each PCB, administered in food from gestational day 7 until weaning at post-natal day 21. PCB 126 impaired motor coordination at 2 months in males but not in females. PCB 153 impaired coordination both in males and females. Combinations of MeHg with PCB153 or PCB126 did not affect motor coordination, indicating that MeHg counteracts the effects of the PBCs. The combination of MeHg and PCB153 induces hypolocomotion at 2 months but hyperactivity at 7 months while the individual compounds did not induce any effect. PCB126 induced gender selective effects, reducing locomotor activity at 2 months in females but not in males. The combination of MeHg and PCB126 behaves as PCB126 alone. All compounds and combinations tested induce gender-selective alterations in vertical activity. The effects on locomotor and vertical activity change with age in the same rats. At 2 months all compounds and combinations reduce vertical activity in females but not in males. At 7 months

  15. Homogeneous catalysis on the gas-phase dehydration reaction of tertiary alcohols by hydrogen bromide. Density functional theory calculation

    NASA Astrophysics Data System (ADS)

    Maldonado, Alexis; Rosas, Felix; Mora, Jose R.; Brusco, Yannely; Córdova-Sintjago, Tania C.; Chuchani, Gabriel

    2015-02-01

    The gas-phase thermal dehydration mechanism of tert-butanol, 2-methyl-2-butanol, 2-methyl-2-pentanol and 2,3-dimethyl-2-butanol by homogeneous catalysis of hydrogen bromide was examined by density functional theory calculations with the hybrid functionals: M062X, CAMB3LYP and WB97XD. Reasonable agreements were found between theoretical and experimental enthalpy values at the WB97XD/6-311++G(d,p) level. The dehydration mechanism of tert-butanol with and without catalysis was evaluated in order to examine the catalyst effect on the mechanism. The elimination reaction without catalysis involves a four-membered transition state (TS), while the reaction with catalysis involves a six-membered TS. The mechanism without catalysis has enthalpy activation over 150 kJ mol-1 greater than the catalysed reaction. In all these reactions, the elongation of the C-O bond is significant in the TS. The un-catalysed reaction is controlled by breaking of C-O bond, and it was found to be more synchronous (Sy ≈ 0.91) than the hydrogen bromide catalysed reactions (Sy ≈ 0.75-0.78); the latter reactions are dominated by the three reaction coordinates associated with water formation. No significant effect on the enthalpies of activation was observed when the size of the alkyl chain was increased.

  16. Intensification of sonochemical degradation of malachite green by bromide ions.

    PubMed

    Moumeni, Ouarda; Hamdaoui, Oualid

    2012-05-01

    Sonochemical oxidation has been investigated as a viable advanced oxidation process (AOP) for the destruction of various pollutants in water. Ultrasonic irradiation generates ()OH radicals that can recombine, react with other gaseous species present in the cavity, or diffuse out of the bubble into the bulk liquid medium where they are able to react with solute molecules. The extent of degradation of an organic dye such as malachite green (MG) is limited by the quantity of hydroxyl radicals diffused from cavitation bubbles. In this work, the effect of bromide ions on sonolytic degradation of MG was investigated. The obtained results clearly demonstrated the considerable enhancement of sonochemical destruction of MG in the presence of bromide. No significant differences were observed in the presence of chloride and sulfate, excluding the salting-out effect. Positive effect of bromide ions, which increases with increasing bromide level and decreasing MG concentration, is due to the generation of dibromine radical anion (Br(2)(-)) formed by reaction of Br(-) with ()OH radicals followed by rapid complexation with another anion. The generated Br(2)(-) radicals, reactive but less than ()OH, are likely able to migrate far from the cavitation bubbles towards the solution bulk and are suitable for degradation of an organic dye such as MG. Additionally, Br(2)(-) radicals undergo radical-radical recombination a