Classification of Chemicals Based On Structured Toxicity ...

EPA Pesticide Factsheets

Thirty years and millions of dollars worth of pesticide registration toxicity studies, historically stored as hardcopy and scanned documents, have been digitized into highly standardized and structured toxicity data within the Toxicity Reference Database (ToxRefDB). Toxicity-based classifications of chemicals were performed as a model application of ToxRefDB. These endpoints will ultimately provide the anchoring toxicity information for the development of predictive models and biological signatures utilizing in vitro assay data. Utilizing query and structured data mining approaches, toxicity profiles were uniformly generated for greater than 300 chemicals. Based on observation rate, species concordance and regulatory relevance, individual and aggregated effects have been selected to classify the chemicals providing a set of predictable endpoints. ToxRefDB exhibits the utility of transforming unstructured toxicity data into structured data and, furthermore, into computable outputs, and serves as a model for applying such data to address modern toxicological problems.

Antinociceptive effects, acute toxicity and chemical composition of Vitex agnus-castus essential oil.

PubMed

Khalilzadeh, Emad; Vafaei Saiah, Gholamreza; Hasannejad, Hamideh; Ghaderi, Adel; Ghaderi, Shahla; Hamidian, Gholamreza; Mahmoudi, Razzagh; Eshgi, Davoud; Zangisheh, Mahsa

2015-01-01

Vitex agnus-castus (VAC) and its essential oil have been traditionally used to treat many conditions and symptoms such as premenstrual problems, mastalgia, inflammation, sexual dysfunction, and pain. In this study, the effects of essential oil extracted from Vitex agnus-castus (EOVAC) leaves were investigated in three behavioral models of nociception in adult male Wistar rats. Chemical composition of EOVAC was analyzed using gas chromatography - mass spectrometry (GC-MS) and also its possible toxicity was determined in mice. Analgesic effect of EOVAC was determined using tail immersion test, formalin test, and acetic acid-induced visceral pain in rats. EOVAC (s.c.) and morphine (i.p.) significantly (p<0.05) reduced pain responses in both formalin and tail immersion tests. In the study of evolved mechanisms, pretreatment with naloxone or atropine significantly (p <0.05) reversed the essential oil-induced analgesia in both formalin and tail immersion tests. Moreover, EOVAC and Piroxicam produced significant (p<0.05) inhibition in the acetic acid-induced writhing response. EOVAC did not show any mortality even at high dose (5 g/kg, p.o.) of administration in toxicity test. Moreover, according to GC-MS results, major components of the EOVAC were α-pinene (14.83%), limonene (10.29%), β-caryophyllene (6.9%), sabinene (5.27%), and β-farnesene (5.9%). These results suggest that endogenous opioidergic system as well as muscarinergic receptors of cholinergic system may be involve in the antinociceptive activity of Vitex agnus-castus essential oil in these models of pain in rats.

Antinociceptive effects, acute toxicity and chemical composition of Vitex agnus-castus essential oil

PubMed Central

Khalilzadeh, Emad; Vafaei Saiah, Gholamreza; Hasannejad, Hamideh; Ghaderi, Adel; Ghaderi, Shahla; Hamidian, Gholamreza; Mahmoudi, Razzagh; Eshgi, Davoud; Zangisheh, Mahsa

2015-01-01

Objective: Vitex agnus-castus (VAC) and its essential oil have been traditionally used to treat many conditions and symptoms such as premenstrual problems, mastalgia, inflammation, sexual dysfunction, and pain. In this study, the effects of essential oil extracted from Vitex agnus-castus (EOVAC) leaves were investigated in three behavioral models of nociception in adult male Wistar rats. Materials and methods: Chemical composition of EOVAC was analyzed using gas chromatography – mass spectrometry (GC-MS) and also its possible toxicity was determined in mice. Analgesic effect of EOVAC was determined using tail immersion test, formalin test, and acetic acid-induced visceral pain in rats. Results: EOVAC (s.c.) and morphine (i.p.) significantly (p<0.05) reduced pain responses in both formalin and tail immersion tests. In the study of evolved mechanisms, pretreatment with naloxone or atropine significantly (p <0.05) reversed the essential oil-induced analgesia in both formalin and tail immersion tests. Moreover, EOVAC and Piroxicam produced significant (p<0.05) inhibition in the acetic acid-induced writhing response. EOVAC did not show any mortality even at high dose (5 g/kg, p.o.) of administration in toxicity test. Moreover, according to GC-MS results, major components of the EOVAC were α-pinene (14.83%), limonene (10.29%), β-caryophyllene (6.9%), sabinene (5.27%), and β-farnesene (5.9%). Conclusions: These results suggest that endogenous opioidergic system as well as muscarinergic receptors of cholinergic system may be involve in the antinociceptive activity of Vitex agnus-castus essential oil in these models of pain in rats. PMID:26101755

DOE contractor's meeting on chemical toxicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1987-01-01

The Office of Health and Environmental Research (OHER) is required to determine the potential health and environmental effects associated with energy production and use. To ensure appropriate communication among investigators and scientific disciplines that these research studies represent, OHER has sponsored workshops. This document provides a compilation of activities at the Third Annual DOE/OHER Workshop. This year's workshop was broadened to include all OHER activities identified as within the chemical effects area. The workshop consisted of eight sessions entitled Isolation and Detection of Toxic chemicals; Adduct Formation and Repair; Chemical Toxicity (Posters); Metabolism and Genotoxicity; Inhalation Toxicology; Gene Regulation; Metalsmore » Toxicity; and Biological Mechanisms. This document contains abstracts of the information presented by session.« less

48 CFR 52.223-14 - Toxic Chemical Release Reporting.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 48 Federal Acquisition Regulations System 2 2010-10-01 2010-10-01 false Toxic Chemical Release....223-14 Toxic Chemical Release Reporting. As prescribed in 23.906(b), insert the following clause: Toxic Chemical Release Reporting (AUG 2003) (a) Unless otherwise exempt, the Contractor, as owner or...

Toxicity evaluation and prediction of toxic chemicals on activated sludge system.

PubMed

Cai, Bijing; Xie, Li; Yang, Dianhai; Arcangeli, Jean-Pierre

2010-05-15

The gaps of data for evaluating toxicity of new or overloaded organic chemicals on activated sludge system resulted in the requirements for methodology of toxicity estimation. In this study, 24 aromatic chemicals typically existed in the industrial wastewater were selected and classified into three groups of benzenes, phenols and anilines. Their toxicity on activated sludge was then investigated. Two indexes of IC(50-M) and IC(50-S) were determined respectively from the respiration rates of activated sludge with different toxicant concentration at mid-term (24h) and short-term (30min) time intervals. Experimental results showed that the group of benzenes was the most toxic, followed by the groups of phenols and anilines. The values of IC(50-M) of the tested chemicals were higher than those of IC(50-S). In addition, quantitative structure-activity relationships (QSARs) models developed from IC(50-M) were more stable and accurate than those of IC(50-S). The multiple linear models based on molecular descriptors and K(ow) presented better reliability than single linear models based on K(ow). Among these molecular descriptors, E(lumo) was the most important impact factor for evaluation of mid-term toxicity. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Yellow phosphorus process to convert toxic chemicals to non-toxic products

DOEpatents

Chang, S.G.

1994-07-26

The present invention relates to a process for generating reactive species for destroying toxic chemicals. This process first contacts air or oxygen with aqueous emulsions of molten yellow phosphorus. This contact results in rapid production of abundant reactive species such as O, O[sub 3], PO, PO[sub 2], etc. A gaseous or liquid aqueous solution organic or inorganic chemicals is next contacted by these reactive species to reduce the concentration of toxic chemical and result in a non-toxic product. The final oxidation product of yellow phosphorus is phosphoric acid of a quality which can be recovered for commercial use. A process is developed such that the byproduct, phosphoric acid, is obtained without contamination of toxic species in liquids treated. A gas stream containing ozone without contamination of phosphorus containing species is also obtained in a simple and cost-effective manner. This process is demonstrated to be effective for destroying many types of toxic organic, or inorganic, compounds, including polychlorinated biphenyls (PCB), aromatic chlorides, amines, alcohols, acids, nitro aromatics, aliphatic chlorides, polynuclear aromatic compounds (PAH), dyes, pesticides, sulfides, hydroxyamines, ureas, dithionates and the like. 20 figs.

Yellow phosphorus process to convert toxic chemicals to non-toxic products

DOEpatents

Chang, Shih-Ger

1994-01-01

The present invention relates to a process for generating reactive species for destroying toxic chemicals. This process first contacts air or oxygen with aqueous emulsions of molten yellow phosphorus. This contact results in rapid production of abundant reactive species such as O, O.sub.3, PO, PO.sub.2, etc. A gaseous or liquid aqueous solution organic or inorganic chemicals is next contacted by these reactive species to reduce the concentration of toxic chemical and result in a non-toxic product. The final oxidation product of yellow phosphorus is phosphoric acid of a quality which can be recovered for commercial use. A process is developed such that the byproduct, phosphoric acid, is obtained without contamination of toxic species in liquids treated. A gas stream containing ozone without contamination of phosphorus containing species is also obtained in a simple and cost-effective manner. This process is demonstrated to be effective for destroying many types of toxic organic, or inorganic, compounds, including polychlorinated biphenyls (PCB), aromatic chlorides, amines, alcohols, acids, nitro aromatics, aliphatic chlorides, polynuclear aromatic compounds (PAH), dyes, pesticides, sulfides, hydroxyamines, ureas, dithionates and the like.

Lead Toxicity to the Performance, Viability, And Community Composition of Activated Sludge Microorganisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yuan, L; Zhi, W; Liu, YS

Lead (Pb) is a prominent toxic metal in natural and engineered systems. Current knowledge on Pb toxicity to the activated sludge has been limited to short-term (<= 24 h) toxicity. The effect of extended Pb exposure on process performance, bacterial viability, and community compositions remains unknown. We quantified the 24-h and 7-day Pb toxicity to chemical oxygen demand (COD) and NH3-N removal, bacterial viability, and community compositions using lab-scale experiments. Our results showed that 7-day toxicity was significantly higher than the short-term 24-h toxicity. Ammonia-oxidizing bacteria were more susceptible than the heterotrophs to Pb toxicity. The specific oxygen uptake ratemore » responded quickly to Pb addition and could serve as a rapid indicator for detecting Pb pollutions. Microbial viability decreased linearly with the amount of added Pb at extended exposure. The bacterial community diversity was markedly reduced with elevated Pb concentrations. Surface analysis suggested that the adsorbed form of Pb could have contributed to its toxicity along with the dissolved form. Our study provides for the first time a systematic investigation of the effect of extended exposure of Pb on the performance and microbiology of aerobic treatment processes, and it indicates that long-term Pb toxicity has been underappreciated by previous studies.« less

America's Poisoned Playgrounds: Children and Toxic Chemicals.

ERIC Educational Resources Information Center

Freedberg, Louis

Next to chemical and farm workers, today's children are at the greatest risk from toxic chemicals. Through their normal play activities, children are exposed to a frightening array of toxic hazards, including lead, pesticides, arsenic, and unknown dangers from abandoned landfills and warehouses. Through a series of documented examples, the author…

Runaway chemical reaction exposes community to highly toxic chemicals.

PubMed

Kaszniak, Mark; Vorderbrueggen, John

2008-11-15

The U.S. Chemical Safety and Hazard Investigation Board (CSB) conducted a comprehensive investigation of a runaway chemical reaction at MFG Chemical (MFG) in Dalton, Georgia on April 12, 2004 that resulted in the uncontrolled release of a large quantity of highly toxic and flammable allyl alcohol and allyl chloride into the community. Five people were hospitalized and 154 people required decontamination and treatment for exposure to the chemicals. This included police officers attempting to evacuate the community and ambulance personnel who responded to 911 calls from residents exposed to the chemicals. This paper presents the findings of the CSB report (U.S. Chemical Safety and Hazard Investigation Board (CSB), Investigation Report: Toxic Chemical Vapor Cloud Release, Report No. 2004-09-I-GA, Washington DC, April 2006) including a discussion on tolling practices; scale-up of batch reaction processes; Process Safety Management (PSM) and Risk Management Plan (RMP) implementation; emergency planning by the company, county and the city; and emergency response and mitigation actions taken during the incident. The reactive chemical testing and atmospheric dispersion modeling conducted by CSB after the incident and recommendations adopted by the Board are also discussed.

Profiling the reproductive toxicity of chemicals from multigeneration studies in the toxicity reference database

EPA Science Inventory

Multigeneration reproduction studies are used to characterize parental and offspring systemic toxicity, as well as reproductive toxicity of pesticides, industrial chemicals and pharmaceuticals. Results from 329 multigeneration studies on 316 chemicals have been digitized into sta...

Effects-driven chemical fractionation of heavy fuel oil to isolate compounds toxic to trout embryos.

PubMed

Bornstein, Jason M; Adams, Julie; Hollebone, Bruce; King, Thomas; Hodson, Peter V; Brown, R Stephen

2014-04-01

Heavy fuel oil (HFO) spills account for approximately 60% of ship-source oil spills and are up to 50 times more toxic than medium and light crude oils. Heavy fuel oils contain elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) and alkyl-PAHs, known to be toxic to fish; however, little direct characterization of HFO toxicity has been reported. An effects-driven chemical fractionation was conducted on HFO 7102 to separate compounds with similar chemical and physical properties, including toxicity, to isolate the groups of compounds most toxic to trout embryos. After each separation, toxicity tests directed the next phase of fractionation, and gas chromatography-mass spectrometry analysis correlated composition with toxicity, with a focus on PAHs. Low-temperature vacuum distillation permitted the separation of HFO into 3 fractions based on boiling point ranges. The most toxic of these fractions underwent wax precipitation to remove long-chain n-alkanes. The remaining PAH-rich extract was further separated using open column chromatography, which provided distinct fractions that were grouped according to increasing aromatic ring count. The most toxic of these fractions was richest in PAHs and alkyl-PAHs. The results of the present study were consistent with previous crude oil studies that identified PAH-rich fractions as the most toxic. © 2013 SETAC.

CADDIS Volume 2. Sources, Stressors and Responses: Unspecified Toxic Chemicals - Simple Conceptual Diagram

EPA Pesticide Factsheets

Intro to the unspecified toxic chemicals module, when to list toxic chemicals as a candidate cause, ways to measure toxic chemicals, simple and detailed conceptual diagrams for toxic chemicals, toxic chemicals module references and literature reviews.

CADDIS Volume 2. Sources, Stressors and Responses: Unspecified Toxic Chemicals - Detailed Conceptual Diagram

EPA Pesticide Factsheets

Intro to the unspecified toxic chemicals module, when to list toxic chemicals as a candidate cause, ways to measure toxic chemicals, simple and detailed conceptual diagrams for toxic chemicals, toxic chemicals module references and literature reviews.

Policy Statement on a New Chemicals Category for Persistent, Bioaccumulative, and Toxic (PBT) Chemicals

EPA Pesticide Factsheets

On November 4, 1999, EPA issued its policy statement on a category for Persistent Bioaccumulative and Toxic (PBT) new chemicals. The statement provides guidance criteria for persistence, bioaccumulation, and toxicity for new chemicals.

2008 Toxic Chemical Release Inventory 2008 Toxic Chemical Release Inventory Community Right-to-Know Act of 1986, Title III, Section 313

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ecology and Air Quality Group

2009-10-01

For reporting year 2008, Los Alamos National Laboratory (LANL) submitted a Form R report for lead as required under the Emergency Planning and Community Right-to- Know Act (EPCRA) Section 313. No other EPCRA Section 313 chemicals were used in 2008 above the reportable thresholds. This document was prepared to provide a description of the evaluation of EPCRA Section 313 chemical use and threshold determinations for LANL for calendar year 2008, as well as to provide background information about data included on the Form R reports. Section 313 of EPCRA specifically requires facilities to submit a Toxic Chemical Release Inventory Reportmore » (Form R) to the U.S. Environmental Protection Agency (EPA) and state agencies if the owners and operators manufacture, process, or otherwise use any of the listed toxic chemicals above listed threshold quantities. EPA compiles this data in the Toxic Release Inventory database. Form R reports for each chemical over threshold quantities must be submitted on or before July 1 each year and must cover activities that occurred at the facility during the previous year. In 1999, EPA promulgated a final rule on persistent bioaccumulative toxics (PBTs). This rule added several chemicals to the EPCRA Section 313 list of toxic chemicals and established lower reporting thresholds for these and other PBT chemicals that were already reportable. These lower thresholds became applicable in reporting year 2000. In 2001, EPA expanded the PBT rule to include a lower reporting threshold for lead and lead compounds. Facilities that manufacture, process, or otherwise use more than 100 lb of lead or lead compounds must submit a Form R.« less

40 CFR 372.22 - Covered facilities for toxic chemical release reporting.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 29 2013-07-01 2013-07-01 false Covered facilities for toxic chemical... (CONTINUED) SUPERFUND, EMERGENCY PLANNING, AND COMMUNITY RIGHT-TO-KNOW PROGRAMS TOXIC CHEMICAL RELEASE REPORTING: COMMUNITY RIGHT-TO-KNOW Reporting Requirements § 372.22 Covered facilities for toxic chemical...

Toxic chemical release weighted ranking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petrocchi, A.J.

1989-07-19

The weighted ranking as used in this report is an attempt to combine total air release with recognized exposure limit for each toxic chemical to arrive at a single ranking factor called Release Exposure Index (REI) which takes both release amount and degree of hazard into consideration. The REIs can then be used in decision making to prioritize how these chemicals are addressed. 2 tabs.

[Chemicals toxic to the olfactory system. Analysis and description].

PubMed

Norès, J M; Biacabe, B; Bonfils, P

2000-10-28

AN IMPORTANT PROBLEM: Occupational exposure to chemical products can have toxic effects on the olfactory system. An important number of patients have experienced olfactory disorders subsequent to the development of the chemical industry and atmospheric pollution. EPIDEMIOLOGY DATA: Straightforward data are difficult to collect because several cofactors other than the toxic product are involved. Two lists of toxic products can be made. The first list includes products for which scientific data is available and the second products for which data is lacking. Olfactory tests also differ between authors and countries. TWO TYPES OF TOXICITY: Acute, accidental toxicity is evidenced by the lesions caused by inhalation of high-doses of strongly toxic agents. Chronic intoxication caused by lower concentrations of these inhaled agents does not produce a trigeminal reflex leading to a modified respiratory rate reducing the airborne aggression. APPROXIMATIONS: Clinical data describing the olfactory toxicity of certain industrial and chemical compounds are very significant but often cannot prove a cause and effect relationship. Data obtained with experimental models in rodents are difficult to extrapolate to humans.

GENE INDUCTION STUDIES AND TOXICITY OF CHEMICAL MIXTURES

EPA Science Inventory

As part of its mixtures program the Agency for Toxic Substances and Disease Registry (ATSDR) supports in vitro and limited in vivo toxicity testing to further our understanding of the toxicity and health effects of chemical mixtures. There are increasing concerns that environment...

Exposure Science for Chemical Prioritization and Toxicity Testing

EPA Science Inventory

Currently, a significant research effort is underway to apply new technologies to screen and prioritize chemicals for toxicity testing as well as to improve understanding of toxicity pathways (Dix et al. 2007, Toxicol Sci; NRC, 2007, Toxicity Testing in the 21st Century; Collins ...

Toxic Chemical Exposure in Schools: Our Children at Risk.

ERIC Educational Resources Information Center

Sterling, Peter; Paquette, Nicole

Asserting that toxic chemicals can be found throughout school grounds in pesticides, building materials, school supplies, cleaning products, office equipment, and personal care products, this reports details the prevalence of toxic chemicals within schools and recommends methods for reducing exposure. Following an executive summary, the report…

Method of forming a chemical composition

DOEpatents

Bingham, Dennis N.; Wilding, Bruce M.; Klingler, Kerry M.; Zollinger, William T.; Wendt, Kraig M.

2007-10-09

A method of forming a chemical composition such as a chemical hydride is described and which includes the steps of selecting a composition having chemical bonds and which is capable of forming a chemical hydride; providing a source of hydrogen; and exposing the selected composition to an amount of ionizing radiation to encourage the changing of the chemical bonds of the selected composition, and chemically reacting the selected composition with the source of hydrogen to facilitate the formation of a chemical hydride.

Comparison of the radiological and chemical toxicity of lead

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beitel, G.A.; Mott, S.

1995-03-01

This report estimates the worst-case radiological dose to an individual from ingested lead containing picocurie levels of radionuclides and then compares the calculated radiological health effects to the chemical toxic effects from that same lead. This comparison provides an estimate of the consequences of inadvertently recycling, in the commercial market, lead containing nominally undetectable concentrations of radionuclides. Quantitative expressions for the radiological and chemical toxicities of lead are based on concentrations of lead in the blood stream. The result shows that the chemical toxicity of lead is a greater health hazard, by orders of magnitude, than any probable companion radiationmore » dose.« less

Review of chemical, medication, and anesthesia toxicity in the OR.

PubMed

Fiedler, M A; Biddle, C

1998-02-01

A host of toxic substances exist in the OR. The toxicity of prep solutions, cleaning chemicals, common medications, and trace anesthetic gases varies greatly. Nurses use, direct others in the use of, or administer potential toxins while breathing air that may be contaminated to some degree with anesthetic vapors. Often, the OR nurse is the neighborhood resource when questions about the toxicity of common chemicals and drugs arise. A general knowledge of the toxicity of these substances improves the nurse's ability to assess the risk from trace anesthetic gases, prevent injury to patients, provide first aid when potentially dangerous exposure occurs, and direct others in the safe use of OR chemicals.

SCREENING FOR TOXIC INDUSTRIAL CHEMICALS USING SEMIPERMEABLE MEMBRANE DEVICES WITH RAPID TOXICITY ASSAYS

EPA Science Inventory

A time-integrated sampling device interfaced with two toxicity-based assays is reported for monitoring volatile toxic industrial chemicals (TICs). Semipermeable membrane devices (SPMDs) using dimethylsulfoxide (DMSO) as the fill solvent accumulated each of 17 TICs from the vapor...

Effect of subchronic zinc toxicity on rat salivary glands and serum composition.

PubMed

Mizari, Nazer; Hirbod-Mobarakeh, Armin; Shahinpour, Shervin; Ghalichi-Tabriz, Mostafa; Beigy, Maani; Yamini, Ali; Dehpour, Ahmad Reza

2012-11-01

Zinc plays an important role in a wide variety of metabolic processes in animal systems. The role of zinc in preservative treatment, fungicidal action and medicine, and addition of supplementary zinc have increased the probability of zinc toxicity, specially the chronic type. It is known that the composition and quantity of saliva influence the oral health. Regarding people's exposure to zinc in routine life and the importance of saliva, our purpose was to investigate the effects of oral zinc intoxication on secretory function in rat salivary glands and also on serum composition. In this study, there were five groups of female rats. Four groups received zinc acetate dehydrate through their drinking water. After 3 months of experiment, the chemical characteristics and flow rate of saliva and weight of salivary glands were determined. The effects of zinc on hematological and chemical factors of plasma were assessed too. Flow rate of submandibular glands was significantly lower in experimental groups and there were significant changes in Na(+), Ca(2+) and K(+) concentration both in saliva and in plasma. The serum glutamate oxaloacetate transaminase, serum glutamate pyruvate transaminase, glucose levels in the plasma and urine creatinine levels were also altered in experimental groups in comparison with the control group. Our results show that zinc toxicity will affect the quantity and quality of saliva probably through changes in the various neurologic pathways to the salivary glands or effects on acinar cells of the salivary glands. Furthermore, our results showed that zinc toxicity will affect the liver and renal function.

The chemical exposure toxicity space (CETS) model: Displaying exposure time, aqueous and organic concentration, activity, and onset of toxicity.

PubMed

Mackay, Donald; Celsie, Alena K D; Parnis, J Mark; McCarty, Lynn S; Arnot, Jon A; Powell, David E

2017-05-01

A 1-compartment toxicokinetic model is used to characterize the chemical exposure toxicity space (CETS), providing a novel graphic tool that can aid in the design of aquatic toxicity tests for fish and for interpreting their results. The graph depicts the solution to the differential equation describing the uptake kinetics of a chemical by a modeled fish under conventional bioassay conditions. The model relates the exposure concentration in the water to a dimensionless time and the onset of toxicity as determined by an estimated or assumed critical body residue or incipient lethal aqueous concentration. These concentration graphs are specific to each chemical and exposure and organism parameters and clearly demonstrate differences in toxicity between chemicals and how factors such as hydrophobicity influence the toxic endpoint. The CETS plots can also be used to assess bioconcentration test conditions to ensure that concentrations are well below toxic levels. Illustrative applications are presented using a recent set of high-quality toxicity data. Conversion of concentrations to chemical activities in the plots enables results for different baseline toxicants to be superimposed. For chemicals that have different modes of toxic action, the increased toxicity then becomes apparent. Implications for design and interpretation of aquatic toxicity tests are discussed. The model, and pictorial visualization of the time-course of aquatic toxicity tests, may contribute to improvements in test design, implementation, and interpretation, and to reduced animal usage. Environ Toxicol Chem 2017;36:1389-1396. © 2016 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC. © 2016 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC.

Differential Toxicity Characterization of Green Alternative Chemicals

EPA Science Inventory

Assessing the toxicity of a chemical across all possible disease domains and understanding its dose- response behavior cost millions to tens of millions of dollars per chemical, and can take years to decades to evaluate fully. This expense and the lack of regulatory requirements ...

DETECTION OF TOXICANTS ON BUILDING SURFACES FOLLOWING CHEMICAL ATTACK

EPA Science Inventory

A critical step prior to reoccupation of any facility following a chemical attack will be the monitoring of toxic compounds on surfaces within that facility. Low level detection of toxicant(s) is necessary to ensure that these compounds have been eliminated after decontamination...

Metal-organic frameworks for the removal of toxic industrial chemicals and chemical warfare agents.

PubMed

Bobbitt, N Scott; Mendonca, Matthew L; Howarth, Ashlee J; Islamoglu, Timur; Hupp, Joseph T; Farha, Omar K; Snurr, Randall Q

2017-06-06

Owing to the vast diversity of linkers, nodes, and topologies, metal-organic frameworks can be tailored for specific tasks, such as chemical separations or catalysis. Accordingly, these materials have attracted significant interest for capture and/or detoxification of toxic industrial chemicals and chemical warfare agents. In this paper, we review recent experimental and computational work pertaining to the capture of several industrially-relevant toxic chemicals, including NH 3 , SO 2 , NO 2 , H 2 S, and some volatile organic compounds, with particular emphasis on the challenging issue of designing materials that selectively adsorb these chemicals in the presence of water. We also examine recent research on the capture and catalytic degradation of chemical warfare agents such as sarin and sulfur mustard using metal-organic frameworks.

Comparison of Chemical Composition of Complex Disinfection Byproduct (DBP) Mixtures Produced by Different Treatment Methods

EPA Science Inventory

Analyses of the chemical composition of complex DBP mixtures, produced by different drinking water treatment processes, are essential to generate toxicity data required for assessing their risks to humans. For mixture risk assessments, whole mixture toxicology studies generally a...

Environmental sentinel biomonitors: integrated response systems for monitoring toxic chemicals

NASA Astrophysics Data System (ADS)

van der Schalie, William H.; Reuter, Roy; Shedd, Tommy R.; Knechtges, Paul L.

2002-02-01

Operational environments for military forces are becoming potentially more dangerous due to the increased number, use, and misuse of toxic chemicals across the entire range of military missions. Defense personnel may be exposed to harmful chemicals as a result of industrial accidents or intentional or unintentional action of enemy, friendly forces, or indigenous populations. While there has been a significant military effort to enable forces to operate safely and survive and sustain operations in nuclear, biological, chemical warfare agent environments, until recently there has not been a concomitant effort associated with potential adverse health effects from exposures of deployed personnel to toxic industrial chemicals. To provide continuous real-time toxicity assessments across a broad spectrum of individual chemicals or chemical mixtures, an Environmental Sentinel Biomonitor (ESB) system concept is proposed. An ESB system will integrate data from one or more platforms of biologically-based systems and chemical detectors placed in the environment to sense developing toxic conditions and transmit time-relevant data for use in risk assessment, mitigation, and/or management. Issues, challenges, and next steps for the ESB system concept are described, based in part on discussions at a September 2001 workshop sponsored by the U.S. Army Center for Environmental Health Research.

The problem of current toxic chemicals management.

PubMed

Tickner, Joel; Geiser, Ken

2004-01-01

In this article, we explore the limitations of current chemicals management policies worldwide and the evolution of new European, International and U.S. policies to address the problem of toxic chemicals control. It is becoming increasingly apparent that current chemicals management policies in Europe and the United States are inadequate. There is a general lack of toxicity and exposure information on chemicals in commerce and the vast majority of chemicals were considered safe until proven guilty in legislation. Governments must then prove each chemical is dangerous through a slow and resource-intensive risk assessment process. For more than a decade, Nordic countries, such as Denmark and Sweden, have actively promoted integrated chemicals policies to address contamination of critical waterways. They have successfully used a variety of voluntary and mandatory policy tools, such as education, procurement, lists of chemicals of concern, eco-labeling, research and development on safer substitutes, and chemical phase-out requirements, to encourage companies using chemicals to reduce their reliance on harmful substances and to develop safer substitutes. While previously isolated to particular countries, innovative and exciting European-wide policies to promote sustainable chemicals management are now moving forward, including the recently published draft Registration, Evaluation and Authorization of CHemicals (REACH) policy of the European Union. A sweeping change in chemicals management policies in Europe is inevitable and it will ultimately affect manufacturers in the U.S. and globally. The European movement provides an opportunity to initiate a discussion on integrated chemicals policy in the U.S. where some innovative initiatives already are underway.

Materials Safety Data Sheets: the basis for control of toxic chemicals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ketchen, E.E.; Porter, W.E.

1979-09-01

The Material Safety Data Sheets contained in this volume are the basis for the Toxic Chemical Control Program developed by the Industrial Hygiene Department, Health Division, ORNL. The three volumes are the update and expansion of ORNL/TM-5721 and ORNL/TM-5722 Material Safety Data Sheets: The Basis for Control of Toxic Chemicals, Volume I and Volume II. As such, they are a valuable adjunct to the data cards issued with specific chemicals. The chemicals are identified by name, stores catalog number where appropriate, and sequence numbers from the NIOSH Registry of Toxic Effects of Chemical Substances, 1977 Edition, if available. The datamore » sheets were developed and compiled to aid in apprising the employees of hazards peculiar to the handling and/or use of specific toxic chemicals. Space limitation necessitate the use of descriptive medical terms and toxicological abbreviations. A glossary and an abbreviation list were developed to define some of those sometimes unfamiliar terms and abbreviations. The page numbers are keyed to the catalog number in the chemical stores at ORNL.« less

Materials Safety Data Sheets: the basis for control of toxic chemicals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ketchen, E.E.; Porter, W.E.

The Material Safety Data Sheets contained in this volume are the basis for the Toxic Chemical Control Program developed by the Industrial Hygiene Department, Health Division, ORNL. The three volumes are the update and expansion of ORNL/TM-5721 and ORNL/TM-5722 Material Safety Data Sheets: The Basis for Control of Toxic Chemicals, Volume I and Volume II. As such, they are a valuable adjunct to the data cards issued with specific chemicals. The chemicals are identified by name, stores catalog number where appropriate, and sequence numbers from the NIOSH Registry of Toxic Effects of Chemical Substances, 1977 Edition, if available. The datamore » sheets were developed and compiled to aid in apprising the employees of hazards peculiar to the handling and/or use of specific toxic chemicals. Space limitation necessitate the use of descriptive medical terms and toxicological abbreviations. A glossary and an abbreviation list were developed to define some of those sometimes unfamiliar terms and abbreviations. The page numbers are keyed to the catalog number in the chemical stores at ORNL.« less

Meta-analysis of toxicity and teratogenicity of 133 chemicals from zebrafish developmental toxicity studies

EPA Science Inventory

Zebrafish developmental toxicity testing is an emerging field, which faces considerable challenges regarding data meta-analysis and the establishment of standardized test protocols. Here, we present an initial correlation study on toxicity of 133 chemicals based on data in the li...

An expert system for prediction of chemical toxicity

USGS Publications Warehouse

Hickey, James P.; Aldridge, Andrew J.; Passino-Reader, Dora R.; Frank, Anthony M.

1992-01-01

The National Fisheries Research Center- Great Lakes has developed an interactive computer program that uses the structure of an organic molecule to predict its acute toxicity to four aquatic species. The expert system software, written in the muLISP language, identifies the skeletal structures and substituent groups of an organic molecule from a user-supplied standard chemical notation known as a SMILES string, and then generates values for four solvatochromic parameters. Multiple regression equations relate these parameters to the toxicities (expressed as log10LC50s and log10EC50s, along with 95% confidence intervals) for four species. The system is demonstrated by prediction of toxicity for anilide-type pesticides to the fathead minnow (Pimephales promelas). This software is designed for use on an IBM-compatible personal computer by personnel with minimal toxicology background for rapid estimation of chemical toxicity. The system has numerous applications, with much potential for use in the pharmaceutical industry

Comparison of Chemical Composition of Complex Disinfection Byproduct (DBP) Mixtures Produced by Different Treatment Methods - slides

EPA Science Inventory

Analyses of the chemical composition of complex DBP mixtures, produced by different drinking water treatment processes, are essential to generate toxicity data required for assessing their risks to humans. For mixture risk assessments, whole mixture toxicology studies generally a...

Insect-gene-activity detection system for chemical and biological warfare agents and toxic industrial chemicals

NASA Astrophysics Data System (ADS)

Mackie, Ryan S.; Schilling, Amanda S.; Lopez, Arturo M.; Rayms-Keller, Alfredo

2002-02-01

Detection of multiple chemical and biological weapons (CBW) agents and/or complex mixtures of toxic industrial chemicals (TIC) is imperative for both the commercial and military sectors. In a military scenario, a multi-CBW attack would create confusion, thereby delaying decontamination and therapeutic efforts. In the commercial sector, polluted sites invariably contain a mixture of TIC. Novel detection systems capable of detecting CBW and TIC are sorely needed. While it may be impossible to build a detector capable of discriminating all the possible combinations of CBW, a detection system capable of statistically predicting the most likely composition of a given mixture is within the reach of current emerging technologies. Aquatic insect-gene activity may prove to be a sensitive, discriminating, and elegant paradigm for the detection of CBW and TIC. We propose to systematically establish the expression patterns of selected protein markers in insects exposed to specific mixtures of chemical and biological warfare agents to generate a library of biosignatures of exposure. The predicting capabilities of an operational library of biosignatures of exposures will allow the detection of emerging novel or genetically engineered agents, as well as complex mixtures of chemical and biological weapons agents. CBW and TIC are discussed in the context of war, terrorism, and pollution.

The comparative toxicity to soil invertebrates of natural chemicals and their synthetic analogues.

PubMed

Whitaker, J; Chaplow, J S; Potter, E; Scott, W A; Hopkin, S; Harman, M; Sims, I; Sorokin, N

2009-07-01

The introduction of Registration, Evaluation and Authorisation of Chemicals (REACH), requires companies to register and risk assess all substances produced or imported in volumes of >1 tonne per year. Extrapolation methods which use existing data for estimating the effects of chemicals are attractive to industry, and comparative data are therefore increasingly in demand. Data on natural toxic chemicals could be used for extrapolation methods such as read-across. To test this hypothesis, the toxicity of natural chemicals and their synthetic analogues were compared using standardised toxicity tests. Two chemical pairs: the napthoquinones, juglone (natural) and 1,4-naphthoquinone (synthetic); and anthraquinones, emodin (natural) and quinizarin (synthetic) were chosen, and their comparative effects on the survival and reproduction of collembolans, earthworms, enchytraeids and predatory mites were assessed. Differences in sensitivity between the species were observed with the predatory mite (Hypoaspis aculeifer) showing the least sensitivity. Within the chemical pairs, toxicity to lethal and sub-lethal endpoints was very similar for the four invertebrate species. The exception was earthworm reproduction, which showed differential sensitivity to the chemicals in both naphthoquinone and anthraquinone pairs. Differences in toxicity identified in the present study may be related to degree of exposure and/or subtle differences in the mode of toxic action for the chemicals and species tested. It may be possible to predict differences by identifying functional groups which infer increased or decreased toxicity in one or other chemical. The development of such techniques would enable the use of read-across from natural to synthetic chemicals for a wider group of compounds.

[Assessment of the relationship of properties of chemical compounds and their toxicity to a unified hygienic standardization for chemicals].

PubMed

Trushkov, V F; Perminov, K A; Sapozhnikova, V V; Ignatova, O L

2013-01-01

The connection of thermodynamic properties and parameters of toxicity of chemical substances was determined. Obtained data are used for the evaluation of toxicity and hygienic rate setting of chemical compounds. The relationship between enthalpy and toxicity of chemical compounds has been established. Orthogonal planning of the experiment was carried out in the course of the investigations. Equation of unified hygienic rate setting in combined, complex, conjunct influence on the organism is presented. Prospects of determination of toxicity and methodology of unified hygienic rate setting in combined, complex, conjunct influence on the organism are presented

Toxicity of fire retardant chemicals to aquatic organisms: Progress report

USGS Publications Warehouse

Hamilton, Steven J.; McDonald, Susan F.; Gaikowski, Mark P.; Buhl, Kevin J.; Ramsey, G.S.

1996-01-01

Fire retardants and suppressants used extensively in North America are often applied in environmentally sensitive areas that may contain endangered, threatened, or economically important plant and animal species. We conducted laboratory acute toxicity tests in both hard and soft waters with five commonly used fire control chemicals (Fire Trol LCG-R, Fire-Trol GTS-R, Phos-Chek D-75-F, Phos-Chek WD-881, and Silv-Ex). Organisms used in the tests included two fish (rainbow trout and fathead minnow), two aquatic invertebrates (Daphnia magna and Hyalella azteca), and a green algae (Selenastrum capricornutum). In general, the green algae was substantially more sensitive to the three non-foam fire chemicals than the animals, the Daphnia were the most sensitive test organism in exposures with foams. The two foams (Silv-Ex and Phos-Chek WD-881) had similar toxicity and were more toxic than the three non-foams. Water quality did not seem to modify the toxicity of the five fire chemicals in a consistent manner.

Integrated Proteomic Approaches for Understanding Toxicity of Environmental Chemicals

EPA Science Inventory

To apply quantitative proteomic analysis to the evaluation of toxicity of environmental chemicals, we have developed an integrated proteomic technology platform. This platform has been applied to the analysis of the toxic effects and pathways of many important environmental chemi...

Computerized in vitro test for chemical toxicity based on tetrahymena swimming patterns

NASA Technical Reports Server (NTRS)

Noever, David A.; Matsos, Helen C.; Cronise, Raymond J.; Looger, Loren L.; Relwani, Rachna A.; Johnson, Jacqueline U.

1994-01-01

An apparatus and method for rapidly determining chemical toxicity was evaluated. The toxicity monitor includes an automated scoring of how motile biological cells (Tetrahymena pyriformis) slow down or otherwise change their swimming patterns in a hostile chemical environment. The device, called the Motility Assay Apparatus (MAA) is tested for 30 second determination of chemical toxicity in 20 aqueous samples containing trace organics and salts. With equal or better detection limits, results compare favorably to in vivo animal tests of eye irritancy, in addition to agreeing for all chemicals with previous manual evaluations of single cell motility.

The Toxicity Data Landscape for Environmental Chemicals

PubMed Central

Judson, Richard; Richard, Ann; Dix, David J.; Houck, Keith; Martin, Matthew; Kavlock, Robert; Dellarco, Vicki; Henry, Tala; Holderman, Todd; Sayre, Philip; Tan, Shirlee; Carpenter, Thomas; Smith, Edwin

2009-01-01

Objective Thousands of chemicals are in common use, but only a portion of them have undergone significant toxicologic evaluation, leading to the need to prioritize the remainder for targeted testing. To address this issue, the U.S. Environmental Protection Agency (EPA) and other organizations are developing chemical screening and prioritization programs. As part of these efforts, it is important to catalog, from widely dispersed sources, the toxicology information that is available. The main objective of this analysis is to define a list of environmental chemicals that are candidates for the U.S. EPA screening and prioritization process, and to catalog the available toxicology information. Data sources We are developing ACToR (Aggregated Computational Toxicology Resource), which combines information for hundreds of thousands of chemicals from > 200 public sources, including the U.S. EPA, National Institutes of Health, Food and Drug Administration, corresponding agencies in Canada, Europe, and Japan, and academic sources. Data extraction ACToR contains chemical structure information; physical–chemical properties; in vitro assay data; tabular in vivo data; summary toxicology calls (e.g., a statement that a chemical is considered to be a human carcinogen); and links to online toxicology summaries. Here, we use data from ACToR to assess the toxicity data landscape for environmental chemicals. Data synthesis We show results for a set of 9,912 environmental chemicals being considered for analysis as part of the U.S. EPA ToxCast screening and prioritization program. These include high-and medium-production-volume chemicals, pesticide active and inert ingredients, and drinking water contaminants. Conclusions Approximately two-thirds of these chemicals have at least limited toxicity summaries available. About one-quarter have been assessed in at least one highly curated toxicology evaluation database such as the U.S. EPA Toxicology Reference Database, U.S. EPA Integrated

Reactive chromophores for sensitive and selective detection of chemical warfare agents and toxic industrial chemicals

NASA Astrophysics Data System (ADS)

Frye-Mason, Greg; Leuschen, Martin; Wald, Lara; Paul, Kateri; Hancock, Lawrence F.

2005-05-01

A reactive chromophore developed at MIT exhibits sensitive and selective detection of surrogates for G-class nerve agents. This reporter acts by reacting with the agent to form an intermediate that goes through an internal cyclization reaction. The reaction locks the molecule into a form that provides a strong fluorescent signal. Using a fluorescent sensor platform, Nomadics has demonstrated rapid and sensitive detection of reactive simulants such as diethyl chloro-phosphate (simulant for sarin, soman, and related agents) and diethyl cyanophosphate (simulant for tabun). Since the unreacted chromophore does not fluoresce at the excitation wavelength used for the cyclized reporter, the onset of fluo-rescence can be easily detected. This fluorescence-based detection method provides very high sensitivity and could enable rapid detection at permissible exposure levels. Tests with potential interferents show that the reporter is very selective, with responses from only a few highly toxic, electrophilic chemicals such as phosgene, thionyl chloride, and strong acids such as HF, HCl, and nitric acid. Dimethyl methyl phosphonate (DMMP), a common and inactive simu-lant for other CW detectors, is not reactive enough to generate a signal. The unique selectivity to chemical reactivity means that a highly toxic and hazardous chemical is present when the reporter responds and illustrates that this sensor can provide very low false alarm rates. Current efforts focus on demonstrating the sensitivity and range of agents and toxic industrial chemicals detected with this reporter as well as developing additional fluorescent reporters for a range of chemical reactivity classes. The goal is to produce a hand-held sensor that can sensitively detect a broad range of chemical warfare agent and toxic industrial chemical threats.

Impact of toxic chemicals on local wastewater treatment plant and the environment

NASA Astrophysics Data System (ADS)

Bennett, Gary F.

1989-05-01

Because toxic chemicals being discharged to sewers were simultaneously interfering with wastewater treatment processes of municipal, biological treatment plants and were passing through these plants to negatively impact the bodies of water to which these plants were discharging, the U.S. Environmental Protection Agency issued regulations governing industrial discharges to municipal sewers. These “Pretreatment Regulations” limit industrial discharges to municipal sewers of heavy metals, oil and grease, acids and bases, and toxic organic chemicals. This paper discusses the evolution of these regulations, the basis for them, the types of regulations (categorical and local), and the rationale for their promulgation based on the impacts of toxics chemicals on the treatment plant and receiving system. Finally, the expected results of these regulations in reducing industrial discharges of toxic chemicals is discussed.

Toxico-Cheminformatics: New and Expanding Public Resources to Support Chemical Toxicity Assessments

EPA Science Inventory

High-throughput screening (HTS) technologies, along with efforts to improve public access to chemical toxicity information resources and to systematize older toxicity studies, have the potential to significantly improve information gathering efforts for chemical assessments and p...

Computerized In Vitro Test for Chemical Toxicity Based on Tetrahymena Swimming Patterns

NASA Technical Reports Server (NTRS)

Noever, David A.; Matsos, Helen C.; Cronise, Raymond J.; Looger, Loren L.; Relwani, Rachna A.; Johnson, Jacqueline U.

1994-01-01

An apparatus and a method for rapidly determining chemical toxicity have been evaluated as an alternative to the rabbit eye initancy test (Draize). The toxicity monitor includes an automated scoring of how motile biological cells (Tetrahymena pyriformis) slow down or otherwise change their swimming patterns in a hostile chemical environment. The method, called the motility assay (MA), is tested for 30 s to determine the chemical toxicity in 20 aqueous samples containing trace organics and salts. With equal or better detection limits, results compare favorably to in vivo animal tests of eye irritancy.

Chemical compositions, methods of making the chemical compositions, and structures made from the chemical compositions

DOEpatents

Yang, Lei; Cheng, Zhe; Liu, Ze; Liu, Meilin

2015-01-13

Embodiments of the present disclosure include chemical compositions, structures, anodes, cathodes, electrolytes for solid oxide fuel cells, solid oxide fuel cells, fuel cells, fuel cell membranes, separation membranes, catalytic membranes, sensors, coatings for electrolytes, electrodes, membranes, and catalysts, and the like, are disclosed.

Acute toxicity of fire control chemicals to Daphnia magna(Straus) and Selenastrum capricornutum(Printz)

USGS Publications Warehouse

McDonald, Susan F.; Hamilton, Steven J.; Buhl, Kevin J.; Heisinger, James F.

1996-01-01

Acute toxicity tests were conducted exposingDaphnia magnaStraus (daphnid) in soft and hard reconstituted waters (hardness 42 and 162 mg/liter as CaCO3, respectively), andSelenastrum capricornutumPrintz (algae) in ASTM algal assay medium (hardness 15 mg/liter as CaCO3) to fire retardants Fire-Trol GTS-R, Fire-Trol LCG-R, and Phos-Chek D75-F, and foam suppressants Phos-Chek WD-881 and Silv-Ex. The chemicals were slightly toxic to practically harmless to daphnids and moderately toxic to algae. Water quality did not consistently alter the toxicity of the test chemicals to daphnids. The most toxic chemical to daphnids was Silv-Ex (48-hr EC507 mg/liter in soft and hard waters), whereas the least toxic chemical to daphnids was Fire-Trol LCG-R (48-hr EC50848 mg/liter in soft water, 813 mg/liter in hard water). The most toxic chemical to algae was Fire-Trol LCG-R (96-hr IC5010 mg/liter), and the least toxic chemical was Phos-Chek D75-F (96-hr IC5079 mg/liter). Un-ionized ammonia concentrations near the EC50or IC50value in tests with the Fire-Trol compounds were frequently equal to or above reported LC50un-ionized ammonia concentrations. Un-ionized ammonia concentrations in tests with Phos-Chek D75-F were low, thus other toxic components present in the compounds probably contributed to the toxicity. When compared to the daphnids tested in ASTM soft water, the Fire-Trol compounds were most toxic to algae, whereas Phos-Chek D75-F and the foam suppressants were most toxic to daphnids. The results of these tests are comparable to those obtained from research conducted in other laboratories with the same species and similar chemicals. Accidental entry of fire-fighting chemicals into aquatic environments could adversely affect algae and aquatic invertebrates, thus disrupting ecosystem function.

Use of fish embryo toxicity tests for the prediction of acute fish toxicity to chemicals.

PubMed

Belanger, Scott E; Rawlings, Jane M; Carr, Gregory J

2013-08-01

The fish embryo test (FET) is a potential animal alternative for the acute fish toxicity (AFT) test. A comprehensive validation program assessed 20 different chemicals to understand intra- and interlaboratory variability for the FET. The FET had sufficient reproducibility across a range of potencies and modes of action. In the present study, the suitability of the FET as an alternative model is reviewed by relating FET and AFT. In total, 985 FET studies and 1531 AFT studies were summarized. The authors performed FET-AFT regressions to understand potential relationships based on physical-chemical properties, species choices, duration of exposure, chemical classes, chemical functional uses, and modes of action. The FET-AFT relationships are very robust (slopes near 1.0, intercepts near 0) across 9 orders of magnitude in potency. A recommendation for the predictive regression relationship is based on 96-h FET and AFT data: log FET median lethal concentration (LC50) = (0.989 × log fish LC50) - 0.195; n = 72 chemicals, r = 0.95, p < 0.001, LC50 in mg/L. A similar, not statistically different regression was developed for the entire data set (n = 144 chemicals, unreliable studies deleted). The FET-AFT regressions were robust for major chemical classes with suitably large data sets. Furthermore, regressions were similar to those for large groups of functional chemical categories such as pesticides, surfactants, and industrial organics. Pharmaceutical regressions (n = 8 studies only) were directionally correct. The FET-AFT relationships were not quantitatively different from acute fish-acute fish toxicity relationships with the following species: fathead minnow, rainbow trout, bluegill sunfish, Japanese medaka, and zebrafish. The FET is scientifically supportable as a rational animal alternative model for ecotoxicological testing of acute toxicity of chemicals to fish. Copyright © 2013 SETAC.

COMPUTER SUPPORT SYSTEMS FOR ESTIMATING CHEMICAL TOXICITY: PRESENT CAPABILITIES AND FUTURE TRENDS

EPA Science Inventory

Computer Support Systems for Estimating Chemical Toxicity: Present Capabilities and Future Trends

A wide variety of computer-based artificial intelligence (AI) and decision support systems exist currently to aid in the assessment of toxicity for environmental chemicals. T...

Chemical composition and Zn bioavailability of the soil solution extracted from Zn amended variable charge soils.

PubMed

Zampella, Mariavittoria; Adamo, Paola

2010-01-01

A study on variable charge soils (volcanic Italian and podzolic Scottish soils) was performed to investigate the influence of soil properties on the chemical composition of soil solution. Zinc speciation, bioavailability and toxicity in the soil solution were examined. The soils were spiked with increasing amounts of Zn (0, 100, 200, 400 and 1000 mg/kg) and the soil solutions were extracted using rhizon soil moisture samplers. The pH, total organic carbon (TOC), base cations, anions, total Zn and free Zn2+ in soil solution were analysed. A rapid bioassay with the luminescent bacterium Escherichia coli HB101 pUCD607 was performed to assess Zn toxicity. The influence of soil type and Zn treatments on the chemical composition of soil solution and on Zn toxicity was considered and discussed. Different trends of total and free Zn concentrations, base cations desorption and luminescence of E. coli HB101 pUCD607 were observed. The soil solution extracted from the volcanic soils had very low total and free Zn concentrations and showed specific Zn2+/Ca2+ exchange. The soil solution from the podzolic soil had much higher total and free Zn concentrations and showed no evidence of specific Zn2+/Ca2+ exchange. In comparison with the subalkaline volcanic soils, the acidic podzol showed enhanced levels of toxic free Zn2+ and consequently stronger effects on E. coli viability.

Toxic Chemicals Use in School Labs Examined.

ERIC Educational Resources Information Center

Chemical and Engineering News, 1982

1982-01-01

The Consumer Product Safety Commission will recommend an information network to inform students and teachers of current toxicity evaluations of chemicals and of possible use of less hazardous substitutes. Lists names of 33 suspected carcinogens and 11 suspected teratogens. (SK)

A FLUORESCENCE BASED ASSAY FOR DNA DAMAGE INDUCED BY TOXIC INDUSTRIAL CHEMICALS

EPA Science Inventory

One of the reported effects for exposure to many of the toxic industrial chemicals is DNA damage. The present study describes a simple, rapid and innovative assay to detect DNA damage resulting from exposure of surrogate DNA to toxic industrial chemicals (acrolein, allylamine, ch...

The underlying toxicological mechanism of chemical mixtures: A case study on mixture toxicity of cyanogenic toxicants and aldehydes to Photobacterium phosphoreum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Dayong; Department of Chemical and Environmental Engineering, Anyang Institute of Technology, Anyang 455000; Lin, Zhifen, E-mail: lzhifen@tongji.edu.cn

Intracellular chemical reaction of chemical mixtures is one of the main reasons that cause synergistic or antagonistic effects. However, it still remains unclear what the influencing factors on the intracellular chemical reaction are, and how they influence on the toxicological mechanism of chemical mixtures. To reveal this underlying toxicological mechanism of chemical mixtures, a case study on mixture toxicity of cyanogenic toxicants and aldehydes to Photobacterium phosphoreum was employed, and both their joint effects and mixture toxicity were observed. Then series of two-step linear regressions were performed to describe the relationships between joint effects, the expected additive toxicities and descriptorsmore » of individual chemicals (including concentrations, binding affinity to receptors, octanol/water partition coefficients). Based on the quantitative relationships, the underlying joint toxicological mechanisms were revealed. The result shows that, for mixtures with their joint effects resulting from intracellular chemical reaction, their underlying toxicological mechanism depends on not only their interaction with target proteins, but also their transmembrane actions and their concentrations. In addition, two generic points of toxicological mechanism were proposed including the influencing factors on intracellular chemical reaction and the difference of the toxicological mechanism between single reactive chemicals and their mixtures. This study provided an insight into the understanding of the underlying toxicological mechanism for chemical mixtures with intracellular chemical reaction. - Highlights: • Joint effects of nitriles and aldehydes at non-equitoxic ratios were determined. • A novel descriptor, ligand–receptor interaction energy (E{sub binding}), was employed. • Quantitative relationships for mixtures were developed based on a novel descriptor. • The underlying toxic mechanism was revealed based on quantitative relationships. �

Predictive Modeling of Chemical Hazard by Integrating Numerical Descriptors of Chemical Structures and Short-term Toxicity Assay Data

PubMed Central

Rusyn, Ivan; Sedykh, Alexander; Guyton, Kathryn Z.; Tropsha, Alexander

2012-01-01

Quantitative structure-activity relationship (QSAR) models are widely used for in silico prediction of in vivo toxicity of drug candidates or environmental chemicals, adding value to candidate selection in drug development or in a search for less hazardous and more sustainable alternatives for chemicals in commerce. The development of traditional QSAR models is enabled by numerical descriptors representing the inherent chemical properties that can be easily defined for any number of molecules; however, traditional QSAR models often have limited predictive power due to the lack of data and complexity of in vivo endpoints. Although it has been indeed difficult to obtain experimentally derived toxicity data on a large number of chemicals in the past, the results of quantitative in vitro screening of thousands of environmental chemicals in hundreds of experimental systems are now available and continue to accumulate. In addition, publicly accessible toxicogenomics data collected on hundreds of chemicals provide another dimension of molecular information that is potentially useful for predictive toxicity modeling. These new characteristics of molecular bioactivity arising from short-term biological assays, i.e., in vitro screening and/or in vivo toxicogenomics data can now be exploited in combination with chemical structural information to generate hybrid QSAR–like quantitative models to predict human toxicity and carcinogenicity. Using several case studies, we illustrate the benefits of a hybrid modeling approach, namely improvements in the accuracy of models, enhanced interpretation of the most predictive features, and expanded applicability domain for wider chemical space coverage. PMID:22387746

Equity and Information: Information Regulation, Environmental Justice, and Risks from Toxic Chemicals

ERIC Educational Resources Information Center

Shapiro, Marc D.

2005-01-01

Decreases over time in pounds of industrial chemical emissions have led to concerns that nonminority, higher-income communities have benefited disproportionately in reductions in risk. Toxic chemical release data, modeled for toxicity and dispersion in square kilometer units across 45 states, are used to test six sets of hypotheses of potential…

Microbial contamination and chemical toxicity of the Rio Grande

PubMed Central

Mendoza, Jose; Botsford, James; Hernandez, Jose; Montoya, Anna; Saenz, Roswitha; Valles, Adrian; Vazquez, Alejandro; Alvarez, Maria

2004-01-01

Background The Rio Grande River is the natural boundary between U.S. and Mexico from El Paso, TX to Brownsville, TX. and is one of the major water resources of the area. Agriculture, farming, maquiladora industry, domestic activities, as well as differences in disposal regulations and enforcement increase the contamination potential of water supplies along the border region. Therefore, continuous and accurate assessment of the quality of water supplies is of paramount importance. The objectives of this study were to monitor water quality of the Rio Grande and to determine if any correlations exist between fecal coliforms, E. coli, chemical toxicity as determined by Botsford's assay, H. pylori presence, and environmental parameters. Seven sites along a 112-Km segment of the Rio Grande from Sunland Park, NM to Fort Hancock, TX were sampled on a monthly basis between January 2000 and December 2002. Results The results showed great variability in the number of fecal coliforms, and E. coli on a month-to-month basis. Fecal coliforms ranged between 0–106 CFU/100 ml while E. coli ranged between 6 to > 2419 MPN. H. pylori showed positive detection for all the sites at different times. Toxicity ranged between 0 to 94% of inhibition capacity (IC). Since values above 50% are considered to be toxic, most of the sites displayed significant chemical toxicity at different times of the year. No significant correlations were observed between microbial indicators and chemical toxicity. Conclusion The results of the present study indicate that the 112-Km segment of the Rio Grande river from Sunland Park, NM to Fort Hancock, TX exceeds the standards for contact recreation water on a continuous basis. In addition, the presence of chemical toxicity in most sites along the 112-Km segment indicates that water quality is an area of concern for the bi-national region. The presence of H. pylori adds to the potential health hazards of the Rio Grande. Since no significant correlation was

Chemical composition, potential toxicity, and quality control procedures of the crude drug of Cyrtopodium macrobulbon.

PubMed

Morales-Sánchez, Viridiana; Rivero-Cruz, Isabel; Laguna-Hernández, Guillermo; Salazar-Chávez, Gerardo; Mata, Rachel

2014-07-03

Cyrtopodium macrobulbon ("cañaveral") has been long used in Mexican traditional medicine for the treatment of painful urinary ailments ("mal de orin") in men. This study was conducted (i) to establish the potential acute toxicity and the antinociceptive activity of some preparations of Cyrtopodium macrobulbon, in order to demonstrate its preclinical efficacy for treating symptoms of "mal de orin"; and (ii) to determine the chemical composition and quality control parameters of this medicinal orchid. The antinociceptive effect was assessed using the acetic acid-induced writhing and the hot-plate tests. Investigation of the acute toxicity was accomplished by the Lorke method. The organic extract (OE) was subjected to conventional phytochemical study using chromatographic conventional procedures. The volatile components profile of the species was accomplished via GC-MS analysis of HS-SPME-adsorbed compounds. Furthermore, an HPLC method to quantify ephemeranthol B (10) was developed and validated according to the International Conference on Harmonization Guidelines. Microscopic anatomy studies were performed using light and scanning electron microscopies. Finally, a potential distribution map was generated using the MaxEnt modeling method. AE and OE were not toxic to mice since the LD50 was higher than 5000 mg/kg. OE was only active in the acetic acid-induced writhing assay at the doses of 100 and 316 mg/kg. Conventional phytochemical analysis of OE led to the isolation and characterization of n-hexacosyl-trans-p-coumarate (1), n-octacosyl-trans-p-coumarate (2), n-triacontyl-trans-p-coumarate (3), 4-methoxy-benzyl alcohol (4), 4-hydroxybenzaldehyde (5), 1,5,7-trimethoxy-9,10-dihydrophenanthrene-2,6-diol (6), confusarin (7), gigantol (8), batatasin III (9), and ephemeranthol B (10). The major volatile components identified by HS-SPME analysis were 6,10,14-trimethyl-2-pentadecanone, eucalyptol (11), and isobornyl formate. An HPLC analytical method for the quantification

Identifying and designing chemicals with minimal acute aquatic toxicity

PubMed Central

Kostal, Jakub; Voutchkova-Kostal, Adelina; Anastas, Paul T.; Zimmerman, Julie Beth

2015-01-01

Industrial ecology has revolutionized our understanding of material stocks and flows in our economy and society. For this important discipline to have even deeper impact, we must understand the inherent nature of these materials in terms of human health and the environment. This paper focuses on methods to design synthetic chemicals to reduce their intrinsic ability to cause adverse consequence to the biosphere. Advances in the fields of computational chemistry and molecular toxicology in recent decades allow the development of predictive models that inform the design of molecules with reduced potential to be toxic to humans or the environment. The approach presented herein builds on the important work in quantitative structure–activity relationships by linking toxicological and chemical mechanistic insights to the identification of critical physical–chemical properties needed to be modified. This in silico approach yields design guidelines using boundary values for physiochemical properties. Acute aquatic toxicity serves as a model endpoint in this study. Defining value ranges for properties related to bioavailability and reactivity eliminates 99% of the chemicals in the highest concern for acute aquatic toxicity category. This approach and its future implementations are expected to yield very powerful tools for life cycle assessment practitioners and molecular designers that allow rapid assessment of multiple environmental and human health endpoints and inform modifications to minimize hazard. PMID:24639521

Identifying and designing chemicals with minimal acute aquatic toxicity.

PubMed

Kostal, Jakub; Voutchkova-Kostal, Adelina; Anastas, Paul T; Zimmerman, Julie Beth

2015-05-19

Industrial ecology has revolutionized our understanding of material stocks and flows in our economy and society. For this important discipline to have even deeper impact, we must understand the inherent nature of these materials in terms of human health and the environment. This paper focuses on methods to design synthetic chemicals to reduce their intrinsic ability to cause adverse consequence to the biosphere. Advances in the fields of computational chemistry and molecular toxicology in recent decades allow the development of predictive models that inform the design of molecules with reduced potential to be toxic to humans or the environment. The approach presented herein builds on the important work in quantitative structure-activity relationships by linking toxicological and chemical mechanistic insights to the identification of critical physical-chemical properties needed to be modified. This in silico approach yields design guidelines using boundary values for physiochemical properties. Acute aquatic toxicity serves as a model endpoint in this study. Defining value ranges for properties related to bioavailability and reactivity eliminates 99% of the chemicals in the highest concern for acute aquatic toxicity category. This approach and its future implementations are expected to yield very powerful tools for life cycle assessment practitioners and molecular designers that allow rapid assessment of multiple environmental and human health endpoints and inform modifications to minimize hazard.

Variation in chemical composition and acaricidal activity against Dermanyssus gallinae of four eucalyptus essential oils.

PubMed

George, David R; Masic, Dino; Sparagano, Olivier A E; Guy, Jonathan H

2009-06-01

The results of this study suggest that certain eucalyptus essential oils may be of use as an alternative to synthetic acaricides in the management of the poultry red mite, Dermanyssus gallinae. At a level of 0.21 mg/cm(2), the essential oil from Eucalyptus citriodora achieved 85% mortality in D. gallinae over a 24 h exposure period in contact toxicity tests. A further two essential oils from different eucalyptus species, namely E. globulus and E. radiata, provided significantly (P < 0.05) lower mite mortality (11 and 19%, respectively). Notable differences were found between the eucalyptus essential oils regarding their chemical compositions. There appeared to be a trend whereby the essential oils that were composed of the fewer chemical components were the least lethal to D. gallinae. It may therefore be the case that the complexity of an essential oil's chemical make up plays an important role in dictating the toxicity of that oil to pests such as D. gallinae.

A Conceptual Framework for Predicting the Toxicity of Reactive Chemicals: Modeling Soft Electrophilicity

EPA Science Inventory

Although the literature is replete with QSAR models developed for many toxic effects caused by reversible chemical interactions, the development of QSARs for the toxic effects of reactive chemicals lacks a consistent approach. While limitations exit, an appropriate starting-point...

Computing Equilibrium Chemical Compositions

NASA Technical Reports Server (NTRS)

Mcbride, Bonnie J.; Gordon, Sanford

1995-01-01

Chemical Equilibrium With Transport Properties, 1993 (CET93) computer program provides data on chemical-equilibrium compositions. Aids calculation of thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93/PC is version of CET93 specifically designed to run within 640K memory limit of MS-DOS operating system. CET93/PC written in FORTRAN.

Alterations in welding process voltage affect the generation of ultrafine particles, fume composition, and pulmonary toxicity.

PubMed

Antonini, James M; Keane, Michael; Chen, Bean T; Stone, Samuel; Roberts, Jenny R; Schwegler-Berry, Diane; Andrews, Ronnee N; Frazer, David G; Sriram, Krishnan

2011-12-01

The goal was to determine if increasing welding voltage changes the physico-chemical properties of the fume and influences lung responses. Rats inhaled 40 mg/m³ (3 h/day × 3 days) of stainless steel (SS) welding fume generated at a standard voltage setting of 25 V (regular SS) or at a higher voltage (high voltage SS) of 30 V. Particle morphology, size and composition were characterized. Bronchoalveolar lavage was performed at different times after exposures to assess lung injury. Fumes collected from either of the welding conditions appeared as chain-like agglomerates of nanometer-sized primary particles. High voltage SS welding produced a greater number of ultrafine-sized particles. Fume generated by high voltage SS welding was higher in manganese. Pulmonary toxicity was more substantial and persisted longer after exposure to the regular SS fume. In summary, a modest raise in welding voltage affected fume size and elemental composition and altered the temporal lung toxicity profile.

Acute toxicity of fire-control chemicals, nitrogenous chemicals, and surfactants to rainbow trout

USGS Publications Warehouse

Buhl, Kevin J.; Hamilton, Steven J.

2000-01-01

Laboratory studies were conducted to determine the acute toxicity of three ammonia-based fire retardants (Fire-Trol LCA-F, Fire-Trol LCM-R, and Phos-Chek 259F), five surfactant-based fire-suppressant foams (FireFoam 103B, FireFoam 104, Fire Quench, ForExpan S, and Pyrocap B-136), three nitrogenous chemicals (ammonia, nitrate, and nitrite), and two anionic surfactants (linear alkylbenzene sulfonate [LAS] and sodium dodecyl sulfate [SDS]) to juvenile rainbow trout Oncorhynchus mykiss in soft water. The descending rank order of toxicity (96-h concentration lethal to 50% of test organisms [96-h LC50]) for the fire retardants was as follows: Phos-Chek 259F (168 mg/L) > Fire-Trol LCA-F (942 mg/L) = Fire-Trol LCM-R (1,141 mg/L). The descending rank order of toxicity for the foams was as follows: FireFoam 103B (12.2 mg/L) = FireFoam 104 (13.0 mg/L) > ForExpan S (21.8 mg/L) > Fire Quench (39.0 mg/L) > Pyrocap B-136 [156 mg/L). Except for Pyrocap B-136, the foams were more toxic than the fire retardants. Un-ionized ammonia (NH3; 0.125 mg/L as N) was about six times more toxic than nitrite (0.79 mg/L NO2-N) and about 13,300 times more toxic than nitrate (1,658 mg/L NO3-N). Linear alkylbenzene sulfonate (5.0 mg/L) was about five times more toxic than SDS (24.9 mg/L). Estimated total ammonia and NH3 concentrations at the 96-h LC50s of the fire retardants indicated that ammonia was the primary toxic component in these formulations. Based on estimated anionic surfactant concentrations at the 96-h LC50s of the foams and reference surfactants, LAS was intermediate in toxicity and SDS was less toxic to rainbow trout when compared with the foams. Comparisons of recommended application concentrations to the test results indicate that accidental inputs of these chemicals into streams require substantial dilutions (100-1,750-fold to reach concentrations nonlethal to rainbow trout.

Toxicity Screening of the ToxCast Chemical Library Using a Zebrafish Developmental Assay

EPA Science Inventory

As part of the chemical screening and prioritization research program of the U.S. Environmental Protection Agency, the toxicity of the 320 ToxCast™ Phase I chemicals were assessed using a vertebrate screen of developmental toxicity. Zebrafish embryos/larvae (Danio rerio) were exp...

Toxic industrial chemicals and chemical weapons: exposure, identification, and management by syndrome.

PubMed

Tomassoni, Anthony J; French, Robert N E; Walter, Frank G

2015-02-01

Toxidromes aid emergency care providers in the context of the patient presenting with suspected poisoning, unexplained altered mental status, unknown hazardous materials or chemical weapons exposure, or the unknown overdose. The ability to capture an adequate chemical exposure history and to recognize toxidromes may reduce dependence on laboratory tests, speed time to delivery of specific antidote therapy, and improve selection of supportive care practices tailored to the etiologic agent. This article highlights elements of the exposure history and presents selected toxidromes that may be caused by toxic industrial chemicals and chemical weapons. Specific antidotes for toxidromes and points regarding their use, and special supportive measures, are presented. Copyright © 2015 Elsevier Inc. All rights reserved.

Assessment of sediment toxicity and chemical concentrations in the San Diego Bay region, California, USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fairey, R.; Roberts, C.; Jacobi, M.

1998-08-01

Sediment quality within San Diego Bay, Mission Bay, and the Tijuana River Estuary of California was investigated as part of an ongoing statewide monitoring effort (Bay Protection and Toxic Cleanup Program). Study objectives were to determine the incidence, spatial patterns, and spatial extent of toxicity in sediments and porewater; the concentration and distribution of potentially toxic anthropogenic chemicals; and the relationships between toxicity and chemical concentrations. Rhepoxynius abronius survival bioassays, grain size, and total organic carbon analyses were performed on 350 sediment samples. Strongylocentrotus purpuratus development bioassays were performed on 164 pore-water samples. Toxicity was demonstrated throughout the San Diegomore » Bay region, with increased incidence and concordance occurring in areas of industrial and shipping activity. Trace metal and trace synthetic organic analyses were performed on 229 samples. Copper, zinc, mercury, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and chlordane were found to exceed ERM (effects range median) or PEL (probable effects level) sediment quality guidelines and were considered the six major chemicals or chemical groups of concern. Statistical analysis of the relationships between amphipod toxicity, bulk phase sediment chemistry, and physical parameters demonstrated few significant linear relationships. Significant differences in chemical levels were found between toxic and nontoxic responses using multivariate and univariate statistics. Potential sources of anthropogenic chemicals were discussed.« less

Sampling the stratum corneum for toxic chemicals.

PubMed

Coman, Garrett; Blickenstaff, Nicholas R; Blattner, Collin M; Andersen, Rosa; Maibach, Howard I

2014-01-01

Dermal exposure is an important pathway in environmental health. Exposure comes from contaminated water, soil, treated surfaces, textiles, aerosolized chemicals, and agricultural products. It can occur in homes, schools, play areas, and work settings in the form of industrial sources, consumer products, or hazardous wastes. Dermal exposure is most likely to occur through contact with liquids, water, soil, sediment, and contaminated surfaces. The ability to detect and measure exposure to toxic materials on the skin is an important environmental health issue. The stratum corneum is the skin's first and principal barrier layer of protection from the outside world. It has a complex structure that can effectively protect against a wide variety of physical, chemical, and biological contaminants. However, there are a variety of chemical agents that can damage the stratum corneum and the underlying epidermis, dermis and subcutis, and/or enter systemic circulation through the skin. There are numerous ways of sampling the stratum corneum for these toxic materials like abrasion techniques, biopsy, suction blistering, imaging, washing, wipe sampling, tape stripping, and spot testing. Selecting a method likely depends on the particular needs of the situation. Hence, there is a need to review practical considerations for their use in sampling the stratum corneum for toxins.

Molecular Mechanisms of Aldehyde Toxicity: A Chemical Perspective

PubMed Central

2015-01-01

Aldehydes are electrophilic compounds to which humans are pervasively exposed. Despite a significant health risk due to exposure, the mechanisms of aldehyde toxicity are poorly understood. This ambiguity is likely due to the structural diversity of aldehyde derivatives and corresponding differences in chemical reactions and biological targets. To gain mechanistic insight, we have used parameters based on the hard and soft, acids and bases (HSAB) theory to profile the different aldehyde subclasses with respect to electronic character (softness, hardness), electrophilic reactivity (electrophilic index), and biological nucleophilic targets. Our analyses indicate that short chain aldehydes and longer chain saturated alkanals are hard electrophiles that cause toxicity by forming adducts with hard biological nucleophiles, e.g., primary nitrogen groups on lysine residues. In contrast, α,β-unsaturated carbonyl derivatives, alkenals, and the α-oxoaldehydes are soft electrophiles that preferentially react with soft nucleophilic thiolate groups on cysteine residues. The aldehydes can therefore be grouped into subclasses according to common electronic characteristics (softness/hardness) and molecular mechanisms of toxicity. As we will discuss, the toxic potencies of these subgroups are generally related to corresponding electrophilicities. For some aldehydes, however, predictions of toxicity based on electrophilicity are less accurate due to inherent physicochemical variables that limit target accessibility, e.g., steric hindrance and solubility. The unsaturated aldehydes are also members of the conjugated type-2 alkene chemical class that includes α,β-unsaturated amide, ketone, and ester derivatives. Type-2 alkenes are electrophiles of varying softness and electrophilicity that share a common mechanism of toxicity. Therefore, exposure to an environmental mixture of unsaturated carbonyl derivatives could cause “type-2 alkene toxicity” through additive interactions

Central nervous system effects and chemical composition of two subspecies of Agastache mexicana; an ethnomedicine of Mexico.

PubMed

Estrada-Reyes, Rosa; López-Rubalcava, C; Ferreyra-Cruz, Octavio Alberto; Dorantes-Barrón, Ana María; Heinze, G; Moreno Aguilar, Julia; Martínez-Vázquez, Mariano

2014-04-11

Agastache mexicana subspecies mexicana (Amm) and xolocotziana (Amx) are used in Mexican traditional medicine to relief cultural affiliation syndromes known as "susto" or "espanto", for "nervous" condition, and as a sleep aid. Despite its intensive use, neuropharmacological studies are scarce, and the chemical composition of the aqueous extracts has not been described. Aims of the study are: (1) To analyze the chemical composition of aqueous extracts from aerial parts of Amm and Amx. (2) To evaluate the anxiolytic-like, sedative, antidepressant-like effects. (3) Analyze the general toxic effects of different doses. Anxiolytic-like and sedative effects were measured in the avoidance exploratory behavior, burying behavior and the hole-board tests. The antidepressant-like actions were studied in the forced swimming and tail suspension tests. Finally, general activity and motor coordination disturbances were evaluated in the open field, inverted screen and rota-rod tests. The acute toxicity of Amm and Amx was determined by calculating their LD50 (mean lethal dose). The chemical analyses were performed employing chromatographic, photometric and HPLC-ESI-MS techniques. Low doses of Amm and Amx (0.1σ1.0mg/kg) induced anxiolytic-like actions; while higher doses (over 10mg/kg) induced sedation and reduced the locomotor activity, exerting a general inhibition in the central nervous system (CNS). Results support the use of Amm and Amx in traditional medicine as tranquilizers and sleep inducers. Additionally, this paper contributes to the knowledge of the chemical composition of the aqueous extracts of these plants. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Toxicity and taste: unequal chemical defences in a mimicry ring.

PubMed

Winters, Anne E; Wilson, Nerida G; van den Berg, Cedric P; How, Martin J; Endler, John A; Marshall, N Justin; White, Andrew M; Garson, Mary J; Cheney, Karen L

2018-06-13

Mimicry of warning signals is common, and can be mutualistic when mimetic species harbour equal levels of defence (Müllerian), or parasitic when mimics are undefended but still gain protection from their resemblance to the model (Batesian). However, whether chemically defended mimics should be similar in terms of toxicity (i.e. causing damage to the consumer) and/or unpalatability (i.e. distasteful to consumer) is unclear and in many studies remains undifferentiated. In this study, we investigated the evolution of visual signals and chemical defences in a putative mimicry ring of nudibranch molluscs. First, we demonstrated that the appearance of a group of red spotted nudibranchs molluscs was similar from the perspective of potential fish predators using visual modelling and pattern analysis. Second, using phylogenetic reconstruction, we demonstrated that this colour pattern has evolved multiple times in distantly related individuals. Third, we showed that these nudibranchs contained different chemical profiles used for defensive purposes. Finally, we demonstrated that although levels of distastefulness towards Palaemon shrimp remained relatively constant between species, toxicity levels towards brine shrimp varied significantly. We highlight the need to disentangle toxicity and taste when considering chemical defences in aposematic and mimetic species, and discuss the implications for aposematic and mimicry signal evolution. © 2018 The Author(s).

Interactions between toxic chemicals and natural environmental factors--a meta-analysis and case studies.

PubMed

Laskowski, Ryszard; Bednarska, Agnieszka J; Kramarz, Paulina E; Loureiro, Susana; Scheil, Volker; Kudłek, Joanna; Holmstrup, Martin

2010-08-15

The paper addresses problems arising from effects of natural environmental factors on toxicity of pollutants to organisms. Most studies on interactions between toxicants and natural factors, including those completed in the EU project NoMiracle (Novel Methods for Integrated Risk Assessment of Cumulative Stressors in Europe) described herein, showed that effects of toxic chemicals on organisms can differ vastly depending purely on external conditions. We compiled data from 61 studies on effects of temperature, moisture and dissolved oxygen on toxicity of a range of chemicals representing pesticides, polycyclic aromatic hydrocarbons, plant protection products of bacterial origin and trace metals. In 62.3% cases significant interactions (p< or =0.05 or less) between natural factors and chemicals were found, reaching 100% for the effect of dissolved oxygen on toxicity of waterborne chemicals. The meta-analysis of the 61 studies showed that the null hypothesis assuming no interactions between toxic chemicals and natural environmental factors should be rejected at p=2.7 x 10(-82) (truncated product method probability). In a few cases of more complex experimental designs, also second-order interactions were found, indicating that natural factors can modify interactions among chemicals. Such data emphasize the necessity of including information on natural factors and their variation in time and across geographic regions in ecological risk assessment. This can be done only if appropriate ecotoxicological test designs are used, in which test organisms are exposed to toxicants at a range of environmental conditions. We advocate designing such tests for the second-tier ecological risk assessment procedures. Copyright 2010 Elsevier B.V. All rights reserved.

Mixed Phylogenetic Signal in Fish Toxicity Data across Chemical Classes

EPA Science Inventory

Chemical use in society is growing rapidly and is one of the five major pressures on biodiversity worldwide. Since empirical toxicity studies of pollutants generally focus on a handful of model organisms, reliable approaches are needed to assess sensitivity to chemicals across th...

EPA'S TOXCAST PROGRAM FOR PREDICTING TOXICITY AND PRIORITIZING ENVIRONMENTAL CHEMICALS

EPA Science Inventory

ToxCast is a research program to predict or forecast toxicity by evaluating a broad spectrum of chemicals and effects; physical-chemical properties, predicted bioactivities, HTS and cell-based assays, and genomics. Data will be interpretively linked to known or predicted toxicol...

Nature and prevalence of non-additive toxic effects in industrially relevant mixtures of organic chemicals.

PubMed

Parvez, Shahid; Venkataraman, Chandra; Mukherji, Suparna

2009-06-01

The concentration addition (CA) and the independent action (IA) models are widely used for predicting mixture toxicity based on its composition and individual component dose-response profiles. However, the prediction based on these models may be inaccurate due to interaction among mixture components. In this work, the nature and prevalence of non-additive effects were explored for binary, ternary and quaternary mixtures composed of hydrophobic organic compounds (HOCs). The toxicity of each individual component and mixture was determined using the Vibrio fischeri bioluminescence inhibition assay. For each combination of chemicals specified by the 2(n) factorial design, the percent deviation of the predicted toxic effect from the measured value was used to characterize mixtures as synergistic (positive deviation) and antagonistic (negative deviation). An arbitrary classification scheme was proposed based on the magnitude of deviation (d) as: additive (< or =10%, class-I) and moderately (10< d < or =30 %, class-II), highly (30< d < or =50%, class-III) and very highly (>50%, class-IV) antagonistic/synergistic. Naphthalene, n-butanol, o-xylene, catechol and p-cresol led to synergism in mixtures while 1, 2, 4-trimethylbenzene and 1, 3-dimethylnaphthalene contributed to antagonism. Most of the mixtures depicted additive or antagonistic effect. Synergism was prominent in some of the mixtures, such as, pulp and paper, textile dyes, and a mixture composed of polynuclear aromatic hydrocarbons. The organic chemical industry mixture depicted the highest abundance of antagonism and least synergism. Mixture toxicity was found to depend on partition coefficient, molecular connectivity index and relative concentration of the components.

Effects of toxic metals and chemicals on biofilm and biocorrosion.

PubMed

Fang, Herbert H P; Xu, Li-Chong; Chan, Kwong-Yu

2002-11-01

Microbes in marine biofilms aggregated into clusters and increased the production of extracellular polymeric substances (EPS), by over 100% in some cases, when the seawater media containing toxic metals and chemicals, such as Cd(II), Cu(II), Pb(II), Zn(II), AI(III), Cr(III), glutaraldehyde, and phenol. The formation of microbial cluster and the increased production of EPS, which contained 84-92% proteins and 8-16% polysaccharides, accelerated the corrosion of the mild steel. However, there was no quantitative relationship between the degree of increased corrosion and the toxicity of metals/chemicals towards sulfate-reducing bacteria, or the increased EPS production.

DEVELOPING COMPUTATIONAL TOOLS FOR PREDICTING CHEMICAL FATE, METABOLISM, AND TOXICITY PATHWAYS

EPA Science Inventory

ORD's research program in Computational Toxicology (CompTox) will enable EPA Program Offices and other regulators to prioritize and reduce toxicity-testing requirements for potentially hazardous chemicals. The CompTox program defines the "toxicity process" as follows : 1) a stre...

Acute toxicity of fire-retardant and foam-suppressant chemicals to yalella azteca (Saussure)

USGS Publications Warehouse

McDonald, Susan F.; Hamilton, Steven J.; Buhl, Kevin J.; Heisinger, James F.

1997-01-01

Acute toxicity tests were conducted with Hyalella azteca Saussure (an amphipod) exposed in soft and hard waters to three fire retardants (Fire-Trol GTS-R, Fire-Trol LCG-R, and Phos-Chek D75-F) and two foam suppressants (Phos-Chek WD-881 and Silv-Ex). The chemicals were slightly to moderately toxic to amphipods. The most toxic chemical to amphipods in soft and hard water was Phos-Chek WD-881 (96-h mean lethal concentration [LC50] equal to 10 mg/L and 22 mg/L, respectively), and the least toxic chemical to amphipods in soft water was Fire-Trol GTS-R (96-h LC50 equal to 127 mg/L) and in hard water was Fire-Trol LCG-R (96-h LC50 equal to 535 mg/L). Concentrations of ammonia in tests with the three fire retardants and both water types were greater than reported LC50 values and probably were the major toxic component. Estimated un-ionized ammonia concentrations near the LC50 were frequently less than the reported LC50 ammonia concentrations for amphipods. The three fire retardants were more toxic in soft water than in hard water even though ammonia and un-ionized ammonia concentrations were higher in hard water tests than in soft water tests. The accidental entry of fire-fighting chemicals into aquatic environments could adversely affect aquatic invertebrates, thereby disrupting ecosystem function.

Dissecting the assays to assess microbial tolerance to toxic chemicals in bioprocessing.

PubMed

Zingaro, Kyle A; Nicolaou, Sergios A; Papoutsakis, Eleftherios T

2013-11-01

Microbial strains are increasingly used for the industrial production of chemicals and biofuels, but the toxicity of components in the feedstock and product streams limits process outputs. Selected or engineered microbes that thrive in the presence of toxic chemicals can be assessed using tolerance assays. Such assays must reasonably represent the conditions the cells will experience during the intended process and measure the appropriate physiological trait for the desired application. We review currently used tolerance assays, and examine the many parameters that affect assay outcomes. We identify and suggest the use of the best-suited assays for each industrial bioreactor operating condition, discuss next-generation assays, and propose a standardized approach for using assays to examine tolerance to toxic chemicals. Copyright © 2013 Elsevier Ltd. All rights reserved.

Mechanical-chemical analyses and sub-chronic systemic toxicity of chemical treated organic bovine bone.

PubMed

Lee, Kwang-il; Lee, Jung-soo; Lee, Keun-soo; Jung, Hong-hee; Ahn, Chan-min; Kim, Young-sik; Shim, Young-bock; Jang, Ju-woong

2015-12-01

Sequentially chemical-treated bovine bone was not only evaluated by mechanical and chemical analyses but also implanted into the gluteal muscles of rats for 12 weeks to investigate potential local pathological effects and systemic toxicities. The test (chemical treated bone) and control (heat treated bone) materials were compared using scanning electron microscope (SEM), x-ray diffraction pattern, inductively coupled plasma analysis, and bending strength test. In the SEM images, the micro-porous structure of heat-treated bone was changed to sintered ceramic-like structure. The structure of bone mineral from test and control materials was analyzed as100% hydroxyapatite. The ratio of calcium (Ca) to potassium (P), the main inorganic elements, was same even though the Ca and P percentages of the control material was relatively higher than the test material. No death or critical symptoms arose from implantation of the test (chemical treated bone) and control (physiological saline) materials during 12 weeks. The implanted sites were macroscopically examined, with all the groups showing non-irritant results. Our results indicate that chemical processed bovine bone has a better mechanical property than the heat treated bone and the implantation of this material does not produce systemic or pathological toxicity. Copyright © 2015 Elsevier Inc. All rights reserved.

Compositions and methods for removal of toxic metals and radionuclides

NASA Technical Reports Server (NTRS)

McKay, David S. (Inventor); Cuero, Raul G. (Inventor)

2007-01-01

The present invention relates to compositions and methods for the removal of toxic metals or radionuclides from source materials. Toxic metals may be removed from source materials using a clay, such as attapulgite or highly cationic bentonite, and chitin or chitosan. Toxic metals may also be removed using volcanic ash alone or in combination with chitin or chitosan. Radionuclides may be removed using volcanic ash alone or in combination with chitin or chitosan.

SIMULATING METABOLISM OF XENOBIOTIC CHEMICALS AS A PREDICTOR OF TOXICITY

EPA Science Inventory

EPA is faced with long lists of chemicals that need to be assessed for hazard. A major gap in evaluating chemical risk is accounting for metabolic activation resulting in increased toxicity. The goals of this project are to develop a capability to forecast the metabolism of xenob...

An in silico algal toxicity model with a wide applicability potential for industrial chemicals and pharmaceuticals.

PubMed

Önlü, Serli; Saçan, Melek Türker

2017-04-01

The authors modeled the 72-h algal toxicity data of hundreds of chemicals with different modes of action as a function of chemical structures. They developed mode of action-based local quantitative structure-toxicity relationship (QSTR) models for nonpolar and polar narcotics as well as a global QSTR model with a wide applicability potential for industrial chemicals and pharmaceuticals. The present study rigorously evaluated the generated models, meeting the Organisation for Economic Co-operation and Development principles of robustness, validity, and transparency. The proposed global model had a broad structural coverage for the toxicity prediction of diverse chemicals (some of which are high-production volume chemicals) with no experimental toxicity data. The global model is potentially useful for endpoint predictions, the evaluation of algal toxicity screening, and the prioritization of chemicals, as well as for the decision of further testing and the development of risk-management measures in a scientific and regulatory frame. Environ Toxicol Chem 2017;36:1012-1019. © 2016 SETAC. © 2016 SETAC.

Phase out persistent, bioaccumulative or highly toxic chemicals.

PubMed

Easthope, Tracey; Valeriano, Laurie

2007-01-01

Chemicals such as lindane, lead compounds, and some brominated flame retardants and organophosphate pesticides are examples of persistent, bio-accumulative, and/or highly toxic chemicals that continue to be used in commerce, although strong evidence exists that they pose threats to human and ecosystem health. These and other chemicals, by virtue of their characteristics, are very difficult to manage without unacceptable threats to workers, the environment, or ecosystems. Chemicals that cannot be safely managed should be prioritized for phase out. A transparent process to further identify and prioritize the list of chemicals for phase out is needed. With few exceptions, the U.S. government lacks the authority or an efficient policy instrument to prevent these high-priority chemicals from being used in products and processes or released to the environment. It also has been very difficult for state and local governments to restrict these chemicals. Policy instruments to efficiently and effectively phase out problematic chemicals are needed at all levels of government.

Interspecies quantitative structure-activity relationships (QSARs) for eco-toxicity screening of chemicals: the role of physicochemical properties.

PubMed

Furuhama, A; Hasunuma, K; Aoki, Y

2015-01-01

In addition to molecular structure profiles, descriptors based on physicochemical properties are useful for explaining the eco-toxicities of chemicals. In a previous study we reported that a criterion based on the difference between the partition coefficient (log POW) and distribution coefficient (log D) values of chemicals enabled us to identify aromatic amines and phenols for which interspecies relationships with strong correlations could be developed for fish-daphnid and algal-daphnid toxicities. The chemicals that met the log D-based criterion were expected to have similar toxicity mechanisms (related to membrane penetration). Here, we investigated the applicability of log D-based criteria to the eco-toxicity of other kinds of chemicals, including aliphatic compounds. At pH 10, use of a log POW - log D > 0 criterion and omission of outliers resulted in the selection of more than 100 chemicals whose acute fish toxicities or algal growth inhibition toxicities were almost equal to their acute daphnid toxicities. The advantage of log D-based criteria is that they allow for simple, rapid screening and prioritizing of chemicals. However, inorganic molecules and chemicals containing certain structural elements cannot be evaluated, because calculated log D values are unavailable.

Estimating Toxicity Pathway Activating Doses for High Throughput Chemical Risk Assessments

EPA Science Inventory

Estimating a Toxicity Pathway Activating Dose (TPAD) from in vitro assays as an analog to a reference dose (RfD) derived from in vivo toxicity tests would facilitate high throughput risk assessments of thousands of data-poor environmental chemicals. Estimating a TPAD requires def...

Toxicity of organic chemical pollution in groundwater downgradient of a landfill (Grindsted, Denmark)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baun, A.; Jensen, S.D.; Bjerg, P.L.

2000-05-01

The aim of the present study was to describe the occurrence and distribution of toxicity related to organic chemical contaminants in the leachate plume downgradient of the Grindsted Landfill (Denmark). A total of 27 groundwater samples were preconcentrated by solid-phase extraction (SPE) using XAD-2 as the resin material. This treatment effectively eliminated sample matrix toxicity caused by inorganic salts and natural organic compounds and produced an aqueous concentrate of the nonvolatile chemical contaminants. The SPE extracts were tested in a battery of standardized short-term aquatic toxicity tests with luminescent bacteria (Vibrio fischeri), algae (Selenastrum capricornutum), and crustaceans (Daphnia magna). Additionalmore » genotoxicity tests were made using the umuC test (Salmonella typhimurium). Biotests with algae and luminescent bacteria were the most sensitive tests. On the basis of results with these two bioassays, it was concluded that SPE extracts of groundwater collected close to the landfill were toxic. The toxicity decreased with the distance from the landfill. At distances greater than 80 m from the border of the landfill, the groundwater toxicity was not significantly different from the background toxicity. SPE extracts were not toxic to Daphnia, and no genotoxicity was observed in the umuC test. The overall findings indicate that a battery of biotests applied on preconcentrated groundwater samples can be a useful tool for toxicity characterization and hazard ranking of groundwater polluted with complex chemical mixtures, such as landfill leachates.« less

Novel approaches to improving the chemical safety of the meat chain towards toxicants.

PubMed

Engel, E; Ratel, J; Bouhlel, J; Planche, C; Meurillon, M

2015-11-01

In addition to microbiological issues, meat chemical safety is a growing concern for the public authorities, chain stakeholders and consumers. Meat may be contaminated by various chemical toxicants originating from the environment, treatments of agricultural production or food processing. Generally found at trace levels in meat, these toxicants may harm human health during chronic exposure. This paper overviews the key issues to be considered to ensure better control of their occurrence in meat and assessment of the related health risk. We first describe potential contaminants of meat products. Strategies to move towards a more efficient and systematic control of meat chemical safety are then presented in a second part, with a focus on emerging approaches based on toxicogenomics. The third part presents mitigation strategies to limit the impact of process-induced toxicants in meat. Finally, the last part introduces methodological advances to refine chemical risk assessment related to the occurrence of toxicants in meat by quantifying the influence of digestion on the fraction of food contaminants that may be assimilated by the human body. Copyright © 2015 Elsevier Ltd. All rights reserved.

EPA’s ToxCast Program for Predicting Toxicity and Prioritizing Chemicals for Further Screening and Testing

EPA Science Inventory

Testing of environmental and industrial chemicals for toxicity potential is a daunting task because of the wide range of possible toxicity mechanisms. Although animal testing is one means of achieving broad toxicity coverage, evaluation of large numbers of chemicals is challengin...

Chemical-agnostic hazard prediction: statistical inference of in vitro toxicity pathways from proteomics responses to chemical mixtures

EPA Science Inventory

Toxicity pathways have been defined as normal cellular pathways that, when sufficiently perturbed as a consequence of chemical exposure, lead to an adverse outcome. If an exposure alters one or more normal biological pathways to an extent that leads to an adverse toxicity outcome...

In silico assessment of the acute toxicity of chemicals: recent advances and new model for multitasking prediction of toxic effect.

PubMed

Kleandrova, Valeria V; Luan, Feng; Speck-Planche, Alejandro; Cordeiro, M Natália D S

2015-01-01

The assessment of acute toxicity is one of the most important stages to ensure the safety of chemicals with potential applications in pharmaceutical sciences, biomedical research, or any other industrial branch. A huge and indiscriminate number of toxicity assays have been carried out on laboratory animals. In this sense, computational approaches involving models based on quantitative-structure activity/toxicity relationships (QSAR/QSTR) can help to rationalize time and financial costs. Here, we discuss the most significant advances in the last 6 years focused on the use of QSAR/QSTR models to predict acute toxicity of drugs/chemicals in laboratory animals, employing large and heterogeneous datasets. The advantages and drawbacks of the different QSAR/QSTR models are analyzed. As a contribution to the field, we introduce the first multitasking (mtk) QSTR model for simultaneous prediction of acute toxicity of compounds by considering different routes of administration, diverse breeds of laboratory animals, and the reliability of the experimental conditions. The mtk-QSTR model was based on artificial neural networks (ANN), allowing the classification of compounds as toxic or non-toxic. This model correctly classified more than 94% of the 1646 cases present in the whole dataset, and its applicability was demonstrated by performing predictions of different chemicals such as drugs, dietary supplements, and molecules which could serve as nanocarriers for drug delivery. The predictions given by the mtk-QSTR model are in very good agreement with the experimental results.

Relevancy in Basic Courses: Considering Toxic Chemical Disposal.

ERIC Educational Resources Information Center

Sollimo, Vincent J.

1985-01-01

A 2-week unit on toxic chemical waste disposal is used in a physical science course for nonscience majors. Descriptions of the unit, supplementary student activities, and student library project are provided. Also provided are selected student responses to a five-question survey on the unit. (JN)

Are antifouling paint particles a continuous source of toxic chemicals to the marine environment?

PubMed

Soroldoni, Sanye; Abreu, Fiamma; Castro, Ítalo Braga; Duarte, Fabio Andrei; Pinho, Grasiela Lopes Leães

2017-05-15

Antifouling paint particles (APPs) are generated during periodical maintenance of boat hulls. Chemical composition and toxicity (either chronic or acute) of APPs found in the sediment was evaluated using the epibenthic copepod Nitokra sp. The APPs analyzed showed the presence of high levels of metals such as Cu (234,247±268μgg -1 ), Zn (112,404±845μgg -1 ) and the booster biocide DCOIT (0.13μgg -1 ). Even at low concentrations (as from 5mgg -1 of APPs by mass of sediment) a significantly decrease in the fecundity was observed in laboratory tests. When the sediment was disturbed in elutriate test, a LC 50 of 0.14% for APPs was found. This study was the first assessment of toxicity associated with the presence of APPs in sediment to benthic organisms, and it calls attention to the need of improving regulations in boatyards and marina areas. Copyright © 2017 Elsevier B.V. All rights reserved.

Predicting organ toxicity using in vitro bioactivity data and chemical structure

EPA Science Inventory

Animal testing alone cannot practically evaluate the health hazard posed by tens of thousands of environmental chemicals. Computational approaches together with high-throughput experimental data may provide more efficient means to predict chemical toxicity. Here, we use a superv...

How Much is Too Much? Toxic Chemicals in High School Labs.

ERIC Educational Resources Information Center

Nagel, Miriam C.

1982-01-01

Lists 37 chemicals classified as suspected carcinogens and suspected teratogens (chemicals capable of producing malformations in an embryo). Offers suggestions to high school chemistry teachers for conducting safe laboratory investigations by avoiding use of these potentially toxic materials. (Author/JN)

Toxicological and chemical investigation of untreated municipal wastewater: Fraction- and species-specific toxicity.

PubMed

Hrubik, Jelena; Glisic, Branka; Tubic, Aleksandra; Ivancev-Tumbas, Ivana; Kovacevic, Radmila; Samardzija, Dragana; Andric, Nebojsa; Kaisarevic, Sonja

2016-05-01

Absence of a municipal wastewater (WW) treatment plant results in the untreated WW discharge into the recipient. The present study investigated toxic effects and chemical composition of water extracts and fractions from untreated WW and recipient Danube River (DR). Samples were prepared by solid-phase extraction and silica gel fractionation and screened for EROD activity and cytotoxicity using aquatic models, comprising of fish liver cells (PLHC-1) and a model of the early development of zebrafish embryos, while rat (H4IIE) and human (HepG2) hepatoma cells served as mammalian models. Polar fraction caused cytotoxicity and increased the EROD activity in PLHC-1 cells, and increased mortality and developmental abnormalities in developing zebrafish embryos. In H4IIE, polar fraction induced inhibition of cell growth and increased EROD activity, whereas HepG2 exerted low or no response to the exposure. Non-polar and medium-polar fractions were ineffective. Tentative identification by GC/MS showed that WW is characterized by the hydrocarbons, alkylphenols, plasticizers, and a certain number of benzene derivatives and organic acids. In DR, smaller number of organic compounds was identified and toxicity was less pronounced than in WW treatments. The present study revealed the potent toxic effect of polar fraction of untreated WW, with biological responses varying in sensitivity across organisms. Obtained results confirmed that fraction- and species-specific toxicity should be considered when assessing health risk of environmental pollution. Copyright © 2016 Elsevier Inc. All rights reserved.

An Acetyltransferase Conferring Tolerance to Toxic Aromatic Amine Chemicals

PubMed Central

Martins, Marta; Rodrigues-Lima, Fernando; Dairou, Julien; Lamouri, Aazdine; Malagnac, Fabienne; Silar, Philippe; Dupret, Jean-Marie

2009-01-01

Aromatic amines (AA) are a major class of environmental pollutants that have been shown to have genotoxic and cytotoxic potentials toward most living organisms. Fungi are able to tolerate a diverse range of chemical compounds including certain AA and have long been used as models to understand general biological processes. Deciphering the mechanisms underlying this tolerance may improve our understanding of the adaptation of organisms to stressful environments and pave the way for novel pharmaceutical and/or biotechnological applications. We have identified and characterized two arylamine N-acetyltransferase (NAT) enzymes (PaNAT1 and PaNAT2) from the model fungus Podospora anserina that acetylate a wide range of AA. Targeted gene disruption experiments revealed that PaNAT2 was required for the growth and survival of the fungus in the presence of toxic AA. Functional studies using the knock-out strains and chemically acetylated AA indicated that tolerance of P. anserina to toxic AA was due to the N-acetylation of these chemicals by PaNAT2. Moreover, we provide proof-of-concept remediation experiments where P. anserina, through its PaNAT2 enzyme, is able to detoxify the highly toxic pesticide residue 3,4-dichloroaniline in experimentally contaminated soil samples. Overall, our data show that a single xenobiotic-metabolizing enzyme can mediate tolerance to a major class of pollutants in a eukaryotic species. These findings expand the understanding of the role of xenobiotic-metabolizing enzyme and in particular of NATs in the adaptation of organisms to their chemical environment and provide a basis for new systems for the bioremediation of contaminated soils. PMID:19416981

[Microplate luminometry for toxicity bioassay of chemicals on luciferase].

PubMed

Ge, Hui-Lin; Liu, Shu-Shen; Chen, Fu; Luo, Jin-Hui; Lü, Dai-Zhu; Su, Bing-Xia

2013-10-01

A new microplate luminometry for the toxicity bioassay of chemicals on firefly luciferase, was developed using the multifunctional microplate reader (SpectraMax M5) to measure the luminous intensity of luciferase. Efects of luciferase concentration, luciferin concentration, ATP concentration, pH, temperature, and reaction time on the luminescence were systematically investigated. It was found that ATP exerted a biphasic response on the luciferase luminescence and the maximum relative light units (RLU) occurred at an ATP concentration of 1.1 x 10(-4) mol x L(-1). The method was successfully employed in the toxic effect test of NaF, NaCl, KBr and NaBF4 on luciferase. Using nonlinear least square technique, the dose-response curves (DRC) of the 4 chemicals were accurately fitted with the coefficient of determination (R2) between the fitted and observed responses being greater than 0.99. The median effective concentration (EC50) of the 4 chemicals were accurately measured from the DRC models. Compared with some literatures, the bioassay is a fast easy-operate and cost-effective method with high accuracy.

A systematic evaluation of chemicals in hydraulic-fracturing fluids and wastewater for reproductive and developmental toxicity.

PubMed

Elliott, Elise G; Ettinger, Adrienne S; Leaderer, Brian P; Bracken, Michael B; Deziel, Nicole C

2017-01-01

Hydraulic-fracturing fluids and wastewater from unconventional oil and natural gas development contain hundreds of substances with the potential to contaminate drinking water. Challenges to conducting well-designed human exposure and health studies include limited information about likely etiologic agents. We systematically evaluated 1021 chemicals identified in hydraulic-fracturing fluids (n=925), wastewater (n=132), or both (n=36) for potential reproductive and developmental toxicity to triage those with potential for human health impact. We searched the REPROTOX database using Chemical Abstract Service registry numbers for chemicals with available data and evaluated the evidence for adverse reproductive and developmental effects. Next, we determined which chemicals linked to reproductive or developmental toxicity had water quality standards or guidelines. Toxicity information was lacking for 781 (76%) chemicals. Of the remaining 240 substances, evidence suggested reproductive toxicity for 103 (43%), developmental toxicity for 95 (40%), and both for 41 (17%). Of these 157 chemicals, 67 had or were proposed for a federal water quality standard or guideline. Our systematic screening approach identified a list of 67 hydraulic fracturing-related candidate analytes based on known or suspected toxicity. Incorporation of data on potency, physicochemical properties, and environmental concentrations could further prioritize these substances for future drinking water exposure assessments or reproductive and developmental health studies.

Elucidating mechanisms of toxic action of dissolved organic chemicals in oil sands process-affected water (OSPW).

PubMed

Morandi, Garrett D; Wiseman, Steve B; Guan, Miao; Zhang, Xiaowei W; Martin, Jonathan W; Giesy, John P

2017-11-01

Oil sands process-affected water (OSPW) is generated during extraction of bitumen in the surface-mining oil sands industry in Alberta, Canada, and is acutely and chronically toxic to aquatic organisms. It is known that dissolved organic compounds in OSPW are responsible for most toxic effects, but knowledge of the specific mechanism(s) of toxicity, is limited. Using bioassay-based effects-directed analysis, the dissolved organic fraction of OSPW has previously been fractionated, ultimately producing refined samples of dissolved organic chemicals in OSPW, each with distinct chemical profiles. Using the Escherichia coli K-12 strain MG1655 gene reporter live cell array, the present study investigated relationships between toxic potencies of each fraction, expression of genes and characterization of chemicals in each of five acutely toxic and one non-toxic extract of OSPW derived by use of effects-directed analysis. Effects on expressions of genes related to response to oxidative stress, protein stress and DNA damage were indicative of exposure to acutely toxic extracts of OSPW. Additionally, six genes were uniquely responsive to acutely toxic extracts of OSPW. Evidence presented supports a role for sulphur- and nitrogen-containing chemical classes in the toxicity of extracts of OSPW. Copyright © 2017 Elsevier Ltd. All rights reserved.

Acute oral toxicities of wildland fire control chemicals to birds

USGS Publications Warehouse

Vyas, N.B.; Spann, J.W.; Hill, E.F.

2009-01-01

Wildland fire control chemicals are released into the environment by aerial and ground applications to manage rangeland, grassland, and forest fires. Acute oral 24 h median lethal dosages (LD50) for three fire retardants (Fire-Trol GTS-R?, Phos-Chek D-75F?, and Fire-Trol LCG-R?) and two Class A fire suppressant foams (Silv-Ex? and Phos-Chek WD881?) were estimated for northern bobwhites, Colinus virginianus, American kestrels, Falco sparverius, and red-winged blackbirds, Agelaius phoeniceus. The LD50s of all chemicals for the bobwhites and red-winged blackbirds and for kestrels dosed with Phos-Chek WD881? and Silv-Ex? were above the predetermined 2000 mg chemical/kg body mass regulatory limit criteria for acute oral toxicity. The LD50s were not quantifiable for kestrels dosed with Fire-Trol GTS-R?, Phos-Chek D-75F?, and Fire-Trol LCG-R? because of the number of birds which regurgitated the dosage. These chemicals appear to be of comparatively low order of acute oral toxicity to the avian species tested.

A Novel Water Delivery System for Administering Volatile Chemicals while Minimizing Chemical Waste in Rodent Toxicity Studies

EPA Science Inventory

Rodent toxicity studies typically use water bottles to administer test chemicals via drinking water. However, water bottles provide inconsistent exposure of volatile chemicals due to varying headspace, as well as lead to excessive waste of test material. In order to refine drin...

A novel water delivery system for administering volatile chemicals while minimizing chemical waste in rodent toxicity sutdies

EPA Science Inventory

Rodent toxicity studies typically use water bottles to administer test chemicals via drinking water. However, water bottles provide inconsistent exposure of volatile chemicals due to varying headspace, as well as lead to excessive waste of test material. In order to refine drinki...

Chemical composition and strength of dolomite geopolymer composites

NASA Astrophysics Data System (ADS)

Aizat, E. A.; Al Bakri, A. M. M.; Liew, Y. M.; Heah, C. Y.

2017-09-01

The chemical composition of dolomite and the compressive strength of dolomite geopolymer composites were studied. The both composites prepared with mechanical mixer manufactured by with rotor speed of 350 rpm and curing in the oven for 24 hours at 80˚C. XRF analysis showThe dolomite raw materials contain fewer amounts of Si and Al but high Ca in its composition. Dolomite geopolymer composites with 20M of NaOH shows greater and optimum compressive strength compared to dolomite geopolymer with other NaOH molarity. This indicated better interaction of dolomite raw material and alkaline activator need high molarity of NaOH in order to increase the reactivity of dolomite.

SIMULATION MODELS FOR ENVIRONMENTAL MULTIMEDIA ANALYSIS OF TOXIC CHEMICALS

EPA Science Inventory

Multimedia understanding of pollutant behavior in the environment is of particular concern for chemicals that are toxic and are subject to accumulation in the environmental media (air, soil, water, vegetation) where biota and human exposure is significant. Multimedia simulation ...

Modeling Reproductive Toxicity for Chemical Prioritization into an Integrated Testing Strategy

EPA Science Inventory

The EPA ToxCast research program uses a high-throughput screening (HTS) approach for predicting the toxicity of large numbers of chemicals. Phase-I tested 309 well-characterized chemicals in over 500 assays of different molecular targets, cellular responses and cell-states. Of th...

Development of a category approach to predict the testicular toxicity of chemical substances structurally related to ethylene glycol methyl ether.

PubMed

Yamada, Takashi; Tanaka, Yushiro; Hasegawa, Ryuichi; Sakuratani, Yuki; Yamazoe, Yasushi; Ono, Atsushi; Hirose, Akihiko; Hayashi, Makoto

2014-12-01

We propose a category approach to assessing the testicular toxicity of chemicals with a similar structure to ethylene glycol methyl ether (EGME). Based on toxicity information for EGME and related chemicals and accompanied by adverse outcome pathway information on the testicular toxicity of EGME, this category was defined as chemicals that are metabolized to methoxy- or ethoxyacetic acid, a substance responsible for testicular toxicity. A Japanese chemical inventory was screened using the Hazard Evaluation Support System, which we have developed to support a category approach for predicting the repeated-dose toxicity of chemical substances. Quantitative metabolic information on the related chemicals was then considered, and seventeen chemicals were finally obtained from the inventory as a shortlist for the category. Available data in the literature shows that chemicals for which information is available on the metabolic formation of EGME, ethylene glycol ethyl ether, methoxy- or ethoxyacetic acid do in fact possess testicular toxicity, suggesting that testicular toxicity is a concern, due to metabolic activation, for the remaining chemicals. Our results clearly demonstrate practical utility of AOP-based category approach for predicting repeated-dose toxicity of chemicals. Copyright © 2014 Elsevier Inc. All rights reserved.

Interaction of toxic chemicals with microplastics: A critical review.

PubMed

Wang, Fen; Wong, Charles S; Chen, Da; Lu, Xingwen; Wang, Fei; Zeng, Eddy Y

2018-08-01

Occurrence of microplastics (MPs) in the environment has attracted great attention as it has become a global concern. This review aims to systematically demonstrate the role of marine microplastic as a novel medium for environmental partitioning of chemicals in the ocean, which can cause toxic effects in the ecological environment. This review assimilated and analyzed available data published between 1972 and 2017 on the interaction between MPs and selected chemicals. Firstly, the review analyzes the occurrence of chemicals in MPs and outlines their distribution patterns. Then possible mechanisms of the interaction between MPs and organic chemicals and potential controlling factors were critically studied. Finally, the hazards of MPs and affiliated organic chemicals to marine organisms were shortly summarized. Copyright © 2018 Elsevier Ltd. All rights reserved.

Toxics Release Inventory Chemical Hazard Information Profiles (TRI-CHIP) Dataset

EPA Pesticide Factsheets

The Toxics Release Inventory (TRI) Chemical Hazard Information Profiles (TRI-CHIP) dataset contains hazard information about the chemicals reported in TRI. Users can use this XML-format dataset to create their own databases and hazard analyses of TRI chemicals. The hazard information is compiled from a series of authoritative sources including the Integrated Risk Information System (IRIS). The dataset is provided as a downloadable .zip file that when extracted provides XML files and schemas for the hazard information tables.

Comparison of toxicity values across zebrafish early life stages and mammalian studies: Implications for chemical testing.

PubMed

Ducharme, Nicole A; Reif, David M; Gustafsson, Jan-Ake; Bondesson, Maria

2015-08-01

With the high cost and slow pace of toxicity testing in mammals, the vertebrate zebrafish has become a tractable model organism for high throughput toxicity testing. We present here a meta-analysis of 600 chemicals tested for toxicity in zebrafish embryos and larvae. Nineteen aggregated and 57 individual toxicity endpoints were recorded from published studies yielding 2695 unique data points. These data points were compared to lethality and reproductive toxicology endpoints analyzed in rodents and rabbits and to exposure values for humans. We show that although many zebrafish endpoints did not correlate to rodent or rabbit acute toxicity data, zebrafish could be used to accurately predict relative acute toxicity through the rat inhalation, rabbit dermal, and rat oral exposure routes. Ranking of the chemicals based on toxicity and teratogenicity in zebrafish, as well as human exposure levels, revealed that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), benzo(a)pyrene, and chlorpyrifos ranked in the top nine of all chemicals for these three categories, and as such should be considered high priority chemicals for testing in higher vertebrates. Copyright © 2014 Elsevier Inc. All rights reserved.

International Federation of Gynecology and Obstetrics opinion on reproductive health impacts of exposure to toxic environmental chemicals.

PubMed

Di Renzo, Gian Carlo; Conry, Jeanne A; Blake, Jennifer; DeFrancesco, Mark S; DeNicola, Nathaniel; Martin, James N; McCue, Kelly A; Richmond, David; Shah, Abid; Sutton, Patrice; Woodruff, Tracey J; van der Poel, Sheryl Ziemin; Giudice, Linda C

2015-12-01

Exposure to toxic environmental chemicals during pregnancy and breastfeeding is ubiquitous and is a threat to healthy human reproduction. There are tens of thousands of chemicals in global commerce, and even small exposures to toxic chemicals during pregnancy can trigger adverse health consequences. Exposure to toxic environmental chemicals and related health outcomes are inequitably distributed within and between countries; universally, the consequences of exposure are disproportionately borne by people with low incomes. Discrimination, other social factors, economic factors, and occupation impact risk of exposure and harm. Documented links between prenatal exposure to environmental chemicals and adverse health outcomes span the life course and include impacts on fertility and pregnancy, neurodevelopment, and cancer. The global health and economic burden related to toxic environmental chemicals is in excess of millions of deaths and billions of dollars every year. On the basis of accumulating robust evidence of exposures and adverse health impacts related to toxic environmental chemicals, the International Federation of Gynecology and Obstetrics (FIGO) joins other leading reproductive health professional societies in calling for timely action to prevent harm. FIGO recommends that reproductive and other health professionals advocate for policies to prevent exposure to toxic environmental chemicals, work to ensure a healthy food system for all, make environmental health part of health care, and champion environmental justice. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

FIELD SCREENING METHODS FOR HAZARDOUS WASTES AND TOXIC CHEMICALS

EPA Science Inventory

The purpose of this document is to present the technical papers that were presented at the Second International Symposium on Field Screening Methods for Hazardous Wastes and Toxic Chemicals. ixty platform presentations were made and included in one of ten sessions: hemical sensor...

Silicate-catalyzed chemical grouting compositions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1972-09-28

Chemical grouting compositions for stabilizing earth, sand, and other porous particulate formations or agglomerates of solids are described. The composition for producing a chemically grouting structure consists of an aqueous base solution of: (1) vegetative polyphenolic material consisting of condensed type tannins, and an aqueous catalyst solution of (2) a water-soluble alkali metal silicate. The polyphenolic material is present in an amount from 5% to 40% based on the weight of the base solution, and the water- soluble alkali metal silicate is present in an amount to provide from 1% to 15% SiOD2U in the silicate compound based on themore » weight of the polyphenolic material. These grouting compositions are completely safe to operating personnel and to surrounding environment, since the potassium or sodium silicate catalysts are nontoxic. (15 claims)« less

Linear solvation energy relationships for toxicity of selected organic chemicals to Daphnia pulex and Daphnia magna

USGS Publications Warehouse

Passino, Dora R.M.; Hickey, James P.; Frank, Anthony M.

1988-01-01

In the Laurentian Great Lakes, more than 300 contaminants have been identified in fish, other biota, water, and sediment. Current hazard assessment of these chemicals by the National Fisheries Research Center-Great Lakes is based on their toxicity, occurrence in the environment, and source. Although scientists at the Center have tested over 70 chemicals with the crustacean Daphnia pulex, the number of experimental data needed to screen the huge array of chemicals in the Great Lakes exceeds the practical capabilities of conducting bioassays. This limitation can be partly circumvented, however, by using mathematical models based on quantitative structure-activity relationships (QSAR) to provide rapid, inexpensive estimates of toxicity. Many properties of chemicals, including toxicity, bioaccumulation and water solubility are well correlated and can be predicted by equations of the generalized linear solvation energy relationships (LSER). The equation we used to model solute toxicity is Toxicity = constant + mVI/100 + s (π* + dδ) + bβm + aαm where VI = intrinsic (Van der Waals) molar volume; π* = molecular dipolarity/polarizability; δ = polarizability 'correction term'; βm = solute hydrogen bond acceptor basicity; and αm = solute hydrogen bond donor acidity. The subscript m designates solute monomer values for α and β. We applied the LSER model to 48-h acute toxicity data (measured as immobilization) for six classes of chemicals detected in Great Lakes fish. The following regression was obtained for Daphnia pulex (concentration = μM): log EC50 = 4.86 - 4.35 VI/100; N = 38, r2 = 0.867, sd = 0.403 We also used the LSER modeling approach to analyze to a large published data set of 24-h acute toxicity for Daphnia magna; the following regression resulted, for eight classes of compounds (concentration = mM): log EC50 = 3.88 - 4.52 VI/100 - 1.62 π* + 1.66 βm - 0.916 αm; N = 62, r2 = 0.859, sd = 0.375 In addition we developed computer software that identifies

The complex interaction between marine debris and toxic chemicals in the ocean.

PubMed

Engler, Richard E

2012-11-20

Marine debris, especially plastic debris, is widely recognized as a global environmental problem. There has been substantial research on the impacts of plastic marine debris, such as entanglement and ingestion. These impacts are largely due to the physical presence of plastic debris. In recent years there has been an increasing focus on the impacts of toxic chemicals as they relate to plastic debris. Some plastic debris acts as a source of toxic chemicals: substances that were added to the plastic during manufacturing leach from plastic debris. Plastic debris also acts as a sink for toxic chemicals. Plastic sorbs persistent, bioaccumulative, and toxic substances (PBTs), such as polychlorinated biphenyls (PCBs) and dioxins, from the water or sediment. These PBTs may desorb when the plastic is ingested by any of a variety of marine species. This broad look at the current research suggests that while there is significant uncertainty and complexity in the kinetics and thermodynamics of the interaction, plastic debris appears to act as a vector transferring PBTs from the water to the food web, increasing risk throughout the marine food web, including humans. Because of the extremely long lifetime of plastic and PBTs in the ocean, prevention strategies are vital to minimizing these risks.

Conditional Toxicity Value (CTV) Predictor: An In Silico Approach for Generating Quantitative Risk Estimates for Chemicals.

PubMed

Wignall, Jessica A; Muratov, Eugene; Sedykh, Alexander; Guyton, Kathryn Z; Tropsha, Alexander; Rusyn, Ivan; Chiu, Weihsueh A

2018-05-01

Human health assessments synthesize human, animal, and mechanistic data to produce toxicity values that are key inputs to risk-based decision making. Traditional assessments are data-, time-, and resource-intensive, and they cannot be developed for most environmental chemicals owing to a lack of appropriate data. As recommended by the National Research Council, we propose a solution for predicting toxicity values for data-poor chemicals through development of quantitative structure-activity relationship (QSAR) models. We used a comprehensive database of chemicals with existing regulatory toxicity values from U.S. federal and state agencies to develop quantitative QSAR models. We compared QSAR-based model predictions to those based on high-throughput screening (HTS) assays. QSAR models for noncancer threshold-based values and cancer slope factors had cross-validation-based Q 2 of 0.25-0.45, mean model errors of 0.70-1.11 log 10 units, and applicability domains covering >80% of environmental chemicals. Toxicity values predicted from QSAR models developed in this study were more accurate and precise than those based on HTS assays or mean-based predictions. A publicly accessible web interface to make predictions for any chemical of interest is available at http://toxvalue.org. An in silico tool that can predict toxicity values with an uncertainty of an order of magnitude or less can be used to quickly and quantitatively assess risks of environmental chemicals when traditional toxicity data or human health assessments are unavailable. This tool can fill a critical gap in the risk assessment and management of data-poor chemicals. https://doi.org/10.1289/EHP2998.

Composition and Chemical Stability of Motor Fuels,

DTIC Science & Technology

Fuels, *Hydrocarbons, Cycloalkanes, Chemical analysis, Gasoline, Diesel fuels, Fuel additives, Chemical reactions, Stability, Jet engine fuels...Aviation gasoline, Aviation fuels, Chemical composition, Aromatic hydrocarbons, Unsaturated hydrocarbons, Storage, USSR, Translations, Fuel systems, Alkanes

Chemical compositional, biological, and safety studies of a novel maple syrup derived extract for nutraceutical applications.

PubMed

Zhang, Yan; Yuan, Tao; Li, Liya; Nahar, Pragati; Slitt, Angela; Seeram, Navindra P

2014-07-16

Maple syrup has nutraceutical potential given the macronutrients (carbohydrates, primarily sucrose), micronutrients (minerals and vitamins), and phytochemicals (primarily phenolics) found in this natural sweetener. We conducted compositional (ash, fiber, carbohydrates, minerals, amino acids, organic acids, vitamins, phytochemicals), in vitro biological, and in vivo safety (animal toxicity) studies on maple syrup extracts (MSX-1 and MSX-2) derived from two declassified maple syrup samples. Along with macronutrient and micronutrient quantification, thirty-three phytochemicals were identified (by HPLC-DAD), and nine phytochemicals, including two new compounds, were isolated and identified (by NMR) from MSX. At doses of up to 1000 mg/kg/day, MSX was well tolerated with no signs of overt toxicity in rats. MSX showed antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH) assay) and anti-inflammatory (in RAW 264.7 macrophages) effects and inhibited glucose consumption (by HepG2 cells) in vitro. Thus, MSX should be further investigated for potential nutraceutical applications given its similarity in chemical composition to pure maple syrup.

Chemical Compositional, Biological, and Safety Studies of a Novel Maple Syrup Derived Extract for Nutraceutical Applications

PubMed Central

2015-01-01

Maple syrup has nutraceutical potential given the macronutrients (carbohydrates, primarily sucrose), micronutrients (minerals and vitamins), and phytochemicals (primarily phenolics) found in this natural sweetener. We conducted compositional (ash, fiber, carbohydrates, minerals, amino acids, organic acids, vitamins, phytochemicals), in vitro biological, and in vivo safety (animal toxicity) studies on maple syrup extracts (MSX-1 and MSX-2) derived from two declassified maple syrup samples. Along with macronutrient and micronutrient quantification, thirty-three phytochemicals were identified (by HPLC-DAD), and nine phytochemicals, including two new compounds, were isolated and identified (by NMR) from MSX. At doses of up to 1000 mg/kg/day, MSX was well tolerated with no signs of overt toxicity in rats. MSX showed antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH) assay) and anti-inflammatory (in RAW 264.7 macrophages) effects and inhibited glucose consumption (by HepG2 cells) in vitro. Thus, MSX should be further investigated for potential nutraceutical applications given its similarity in chemical composition to pure maple syrup. PMID:24983789

THE FUTURE OF TOXICOLOGY-PREDICTIVE TOXICOLOGY: AN EXPANDED VIEW OF CHEMICAL TOXICITY

EPA Science Inventory

A chemistry approach to predictive toxicology relies on structure−activity relationship (SAR) modeling to predict biological activity from chemical structure. Such approaches have proven capabilities when applied to well-defined toxicity end points or regions of chemical space. T...

Handbook of acute toxicity of chemicals to fish and aquatic invertebrates : summaries of toxicity tests conducted at Columbia National Fisheries Research Laboratory, 1965-78

USGS Publications Warehouse

Johnson, W. Waynon; Finley, Mack T.

1980-01-01

Acute toxicity is a major subject of research at Columbia National Fisheries Research Laboratory for evaluating the impact of toxic chemicals on fishery resources. The Laboratory has played a leading role in developing research technology for toxicity testing and data interpretation. In 1965-78, more than 400 chemicals were tested against a variety of invertebrates and fish species representative of both cold- and warm-water climates.The use of acute toxicity tests for assessing the potential hazard of chemical contaminants to aquatic organisms is well documented (Boyd 1957; Henderson et al. 1960; Sanders and Cope 1966; Macek and McAllister 1970). Static acute toxicity tests provide rapid and (within limits) reproducible concentration-response curves for estimating toxic effects of chemicals on aquatic organisms. These tests provide a database for determining relative toxicity of a large number of chemicals to a variety of species and for estimating acute effects of chemical spills on natural aquatic systems; they also assist in determining priority and design of additional toxicity studies.Acute toxicity tests usually provide estimates of the exposure concentration causing 50% mortality (LC50) to test organisms during a specified period of time. For certain invertebrates, the effective concentration is based on immobilization, or some other identifiable endpoint, rather than on lethality. The application of the LC50 has gained acceptance among toxicologists and is generally the most highly rated test for assessing potential adverse effects of chemical contaminants to aquatic life (Brungs and Mount 1978; American Institute for Biological Sciences 1978a).The literature contains numerous papers dealing with the acute toxicity of chemicals to freshwater organisms. However, there is a tremendous need for a concise compendium of toxicity data covering a large variety of chemicals and test species. This Handbook is a compilation of a large volume of acute toxicity data

THE TOXCAST PROGRAM FOR PRIORITIZING TOXICITY TESTING OF ENVIRONMENTAL CHEMICALS

EPA Science Inventory

The United States Environmental Protection Agency (EPA) is developing methods for utilizing computational chemistry, high-throughput screening (HTS) and various toxicogenomic technologies to predict potential for toxicity and prioritize limited testing resources towards chemicals...

INVERSE QUANTITATIVE STRUCTURE ACTIVITY RELATIONSHIP ANALYSIS FOR IMPROVING PREDICTIONS OF CHEMICAL TOXICITY

EPA Science Inventory

The toxic outcomes associated with environmental contaminants are often not due to the chemical form that was originally introduced into the environment, but rather to the chemical having undergone a transformation prior to reaching the vulnerable species. More importantly, the c...

ToxCast: Developing Predictive Signatures of Chemically Induced Toxicity (S)

EPA Science Inventory

ToxCast, the United States Environmental Protection Agency’s chemical prioritization research program, is developing methods for utilizing computational chemistry, bioactivity profiling and toxicogenomic data to predict potential for toxicity and prioritize limited testing resour...

Lunar Skylights and Their Chemical Compositions

NASA Astrophysics Data System (ADS)

Wong, J.; Torres, J.; FitzHoward, S.; Luu, E.; Hua, J.; Irby, R.

2013-12-01

In 2009, the Japanese orbiter, SELenological and Engineering Explorer (SELENE) discovered a skylight on the near side of the moon. Skylights are collapsed ceilings of rilles, thought to be caused by moonquakes, meteoroids, or incomplete formation of these lava tube ceilings. Since then, NASA's Lunar Reconnaissance Orbiter has discovered two more skylights, also located on the near side of the moon. Previous research has shown that the physical characteristics of known rilles, can be used as indicators of the presence of yet undiscovered rille and lava dome locations across the lunar surface. We hypothesize that skylights have a signature chemical composition that is unique, and can be used to predict the location of additional skylights on the surface of the moon. For this study, we compared chemical composition data of the three mare sites containing skylights with the 21 mare sites without skylights. Using the software JMARS for the Moon, we compiled multiple datasets to measure the concentrations of 13 different chemical compounds including calcium, iron oxide, titanium dioxide, and thorium. We then conducted a two-tailed T-test of the data, which generated probability values for the mean differences across all 13 chemical compounds of the maria sites with skylights and the maria sites without skylights. Our results show that there is no statistical difference in chemical composition across all of the maria sites examined. Therefore, we conclude that chemical composition does not predict or indicate potential skylight locations on the moon. Further research on other skylight characteristics, for example depth and surrounding underground lava channels, may shed light on the relationships between mare and skylights locations. Three Skylight Locations Found on Lunar Surface 100m View of Mare Tranquilitatis Skylight

Metal and anion composition of two biopolymeric chemical stabilizers and toxicity risk implication for the environment.

PubMed

Ndibewu, P P; Mgangira, M B; Cingo, N; McCrindle, R I

2010-01-01

The objective of this study was to (1) measure the concentration of four anions (Cl(-), F(-), [image omitted], and [image omitted]) and nine other elements (Al, Ba, Ca, K, Mg, Mn, Fe, Ni, and Si) in two nontraditional biopolymeric chemical stabilizers (EBCS1 and EBCS2), (2) investigate consequent environmental toxicity risk implications, and (3) create awareness regarding environmental health issues associated with metal concentration levels in enzyme-based chemical stabilizers that are now gaining widespread application in road construction and other concrete materials. Potential ecotoxicity impacts were studied on aqueous extracts of EBCS1 and EBCS2 using two thermodynamic properties models: the Pitzer-Mayorga model (calculation of the electrolyte activity coefficients) and the Millero-Pitzer model (calculation of the ionic activity coefficients). Results showed not only high concentrations of a variety of metal ions and inorganic anions, but also a significant variation between two chemical stabilizing mixtures. The mixture (EBCS2) with the lower pH value was richer in all the cationic and anionic species than (EBCS1). Sulfate (SO(2-)(4)) concentrations were found to be higher in EBCS2 than in EBCS1. There was no correlation between electrolyte activity and presence of the ionic species, which may be linked to a possible high ionic environmental activity. The concentrations of trace metals found (Mn, Fe, and Ni) were low compared to those of earth metals (Ba, Ca, K, and Mg). The metal concentrations were higher in EBCS1 than in EBCS2. Data suggest that specific studies are needed to establish "zero" permissible metal ecotoxicity values for elements and anions in any such strong polyelectrolytic enzyme-based chemical stabilizers.

Temperature-dependent toxicities of four common chemical pollutants to the marine medaka fish, copepod and rotifer.

PubMed

Li, Adela J; Leung, Priscilla T Y; Bao, Vivien W W; Yi, Andy X L; Leung, Kenneth M Y

2014-10-01

We hypothesize that chemical toxicity to marine ectotherms is the lowest at an optimum temperature (OT) and it exacerbates with increasing or decreasing temperature from the OT. This study aimed to verify this hypothetical temperature-dependent chemical toxicity (TDCT) model through laboratory experiments. Acute toxicity over a range of temperatures was tested on four commonly used chemicals to three marine ectotherms. Our results confirmed that toxicities, in terms of 96-h LC50 (median lethal concentration; for the marine medaka fish Oryzias melastigma and the copepod Tigriopus japonicus) and 24-h LC50 (for the rotifer Brachionus koreanus), were highly temperature-dependent, and varied between test species and between study chemicals. The LC50 value of the fish peaked at 20 °C for copper (II) sulphate pentahydrate and triphenyltin chloride, and at 25 °C for dichlorophenyltrichloroethane and copper pyrithione, and decreased with temperature increase or decrease from the peak (i.e., OT). However, LC50 values of the copepod and the rotifer generally showed a negative relationship with temperature across all test chemicals. Both copepod and rotifer entered dormancy at the lowest temperature of 4 °C. Such metabolic depression responses in these zooplanktons could reduce their uptake of the chemical and hence minimize the chemical toxicity at low temperatures. Our TDCT model is supported by the fish data only, whereas a simple linear model fits better to the zooplankton data. Such species-specific TDCT patterns may be jointly ascribed to temperature-mediated changes in (1) the physiological response and susceptibility of the marine ectotherms to the chemical, (2) speciation and bioavailability of the chemical, and (3) toxicokinetics of the chemical in the organisms.

Establishing a Cell-based Assay for Assessment of Cellular Metabolism on Chemical Toxicity

EPA Science Inventory

A major drawback of current in vitro chemical testing is that many commonly used cell lines lack chemical metabolism. To help address this challenge, we are established a method for assessing the impact of cellular metabolism on chemical-based cellular toxicity. A commonly used h...

Biocidal Potential and Chemical Composition of Industrial Essential Oils from Hyssopus officinalis, Lavandula × intermedia var. Super, and Santolina chamaecyparissus.

PubMed

Ortiz de Elguea-Culebras, Gonzalo; Sánchez-Vioque, Raúl; Berruga, María Isabel; Herraiz-Peñalver, David; González-Coloma, Azucena; Andrés, María Fé; Santana-Méridas, Omar

2018-01-01

This work presents the biocidal (insecticidal, ixodicidal, nematicidal, and phytotoxic) effects and chemical compositions of three essential oils obtained from the industrial steam distillation (IEOs) of hyssop (Hyssopus officinalis L.), lavandin (Lavandula × intermedia or L. × hybrida var. Super), and cotton lavender (Santolina chamaecyparissus L.). Their chemical composition analyzed by gas chromatography coupled to mass spectrometry showed 1,8-cineole (53%) and β-pinene (16%) as the major components of H. officinalis, linalyl acetate (38%) and linalool (29%) of L. × intermedia; and 1,8-cineole (10%) and 8-methylene-3-oxatricyclo[5.2.0.0 2,4 ]nonane (8%) in S. chamaecyparissus. The biocidal tests showed that L. × intermedia IEO was the most active against the insect Spodoptera littoralis and toxic to the tick Hyalomma lusitanicum, IEO of H. officinalis was strongly active against S. littoralis, and finally, S. chamaecyparissus IEO was a strong antifeedant against the aphid Rhopalosiphum padi, toxic to H. lusitanicum and with moderate effects against Leptinotarsa decemlineata, S. littoralis, and Lolium perenne. © 2018 Wiley-VHCA AG, Zurich, Switzerland.

Probing the ToxCast Chemical Library for Predictive Signatures of Developmental Toxicity

EPA Science Inventory

EPA’s ToxCast™ project is profiling the in vitro bioactivity of chemical compounds to assess pathway-level and cell-based signatures that correlate with observed in vivo toxicity. We hypothesize that cell signaling pathways are primary targets for diverse environmental chemicals ...

VAPOR SAMPLING DEVICE FOR INTERFACE WITH MICROTOX ASSAY FOR SCREENING TOXIC INDUSTRIAL CHEMICALS

EPA Science Inventory

A time-integrated sampling system interfaced with a toxicity-based assay is reported for monitoring volatile toxic industrial chemicals (TICs). Semipermeable membrane devices (SPMDs) using dimethyl sulfoxide (DMSO) as the fill solvent accumulated each of 17 TICs from the vapor...

Biomedical Platforms Based on Composite Nanomaterials and Cellular Toxicity

NASA Astrophysics Data System (ADS)

Bellucci, Stefano; Bergamaschi, A.; Bottini, M.; Magrini, A.; Mustelin, T.

2007-03-01

Carbon nanotubes possess unique chemical, physical, optical, and magnetic properties, which make them suitable for many uses in industrial products and in the field of nanotechnology, including nanomedicine. We describe fluorescent nanocomposites for use in biosensors or nanoelectronics. Then we describe recent results on the issue of cytotoxicity of carbon nanotubes obtained in our labs. Silica nanoparticles have been widely used for biosensing and catalytic applications due to their large surface area-to-volume ratio, straightforward manufacture, and the compatibility of silica chemistry with covalent coupling of biomolecules. Carbon nanotubes-composite materials, such as those based on Carbon nanotubes bound to nanoparticles, are suitable, in order to tailor Carbon nanotubes properties for specific applications. We present a tunable synthesis of Multi Wall Carbon nanotubes-Silica nanoparticles. The control of the nanotube morphology and the bead size, coupled with the versatility of silica chemistry, makes these structures an excellent platform for the development of biosensors (optical, magnetic and catalytic applications). We describe the construction and characterization of supramolecular nanostructures consisting of ruthenium-complex luminophores, directly grafted onto short oxidized single-walled carbon nanotubes or physically entrapped in silica nanobeads, which had been covalently linked to short oxidized single-walled carbon nanotubes or hydrophobically adsorbed onto full-length multi-walled carbon nanotubes. These structures have been evaluated as potential electron-acceptor complexes for use in the fabrication of photovoltaic devices, and for their properties as fluorescent nanocomposites for use in biosensors or nanoelectronics. Finally, we compare the toxicity of pristine and oxidized Multi Walled Carbon nanotubes on human T cells - which would be among the first exposed cell types upon intravenous administration of Carbon nanotubes in therapeutic

Using Molecular Docking to Compare Toxicity of Reactive Chemicals to Freshwater and Marine Luminous Bacteria.

PubMed

Gao, Ya; Lin, Zhifen; Chen, Rui; Wang, Ting; Liu, Shushen; Yao, Zhifeng; Yin, Daqiang

2012-12-01

Vibrio fischeri is a marine luminous bacterium that has been widely used in toxicity bioassays, while Vibrio qinghaiensis sp.-Q67 is a newly found freshwater species which is more suitable for the tests on freshwater samples. However, there is a sensitive difference between these two species due to the media, chemical modes of action and the tested species. It remains unclear how these factors induce toxicity changes in luminous bioassays. Therefore, by using molecular docking between reactive chemicals and the target proteins of Vibrio fischeri and Vibrio qinghaiensis sp.-Q67 respectively, the sensitive difference was explored from the angle of amino acid residues that involved in the interactions. Mutation of amino acid residues was performed to investigate the role of these amino acids in the interactions and the most important amino acid residues in toxicity effect were found. The results suggested tat the most important amino acid residues in toxicity effect would affect the binding affinity between chemicals and target proteins of Vibrio fischeri and Vibrio qinghaiensis sp.-Q67, and then induce distinct toxic effect on them. As there are fewer toxicity data for freshwater Vibrio qinghaiensis sp.-Q67 than for Vibrio fischeri, this study helps to take advantage of the plentiful toxicity data of Vibrio fischeri to predict toxicities of freshwater samples. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Increased Susceptibility to Chemical Toxicity with Pre-existing ...

EPA Pesticide Factsheets

Numerous host and environmental factors may modulate vulnerability and risk. An area of increasing interest to risk assessors is the potential for chemicals to interact with pre-existing diseases and aging that may yield cumulative damage, altered chemical response, and increased disease susceptibility. We evaluated the relationships between chemicals and pre-existing disease and identify the type of information needed to evaluate the relationships of interest. Key among these is the existence of a clinically relevant and easy to measure biomarker of disease risk which is also modulated by a particular chemical of interest. This biomarker may be a physiological, biochemical, or genetic indicator that corresponds to a phase of the disease process and may be an indicator of where an individual is on the continuum of disease or health status. The relationship between chemical exposure and a biomarker may then be used to predict how preexisting conditions may modify health risks of chemical exposures. Several case studies are explored to describe the toxic chemical, the clinical biomarker, the impacted disease and the evidence that the chemical enhances disease risk: fine particulate matter/decreased heart rate variability/increased cardiopulmonary events; cadmium/decreased glomerular filtration ate/increased chronic kidney disease; methyl mercury/decreased paraoxonase-1/increased cardiovascular risk; Trichloroethylene/increased anti-nuclear antibody/autoimmunit

Toxicity challenges in environmental chemicals: Prediction of ...

EPA Pesticide Factsheets

Physiologically based pharmacokinetic (PBPK) models bridge the gap between in vitro assays and in vivo effects by accounting for the adsorption, distribution, metabolism, and excretion of xenobiotics, which is especially useful in the assessment of human toxicity. Quantitative structure-activity relationships (QSAR) serve as a vital tool for the high-throughput prediction of chemical-specific PBPK parameters, such as the fraction of a chemical unbound by plasma protein (Fub). The presented work explores the merit of utilizing experimental pharmaceutical Fub data for the construction of a universal QSAR model, in order to compensate for the limited range of high-quality experimental Fub data for environmentally relevant chemicals, such as pollutants, pesticides, and consumer products. Independent QSAR models were constructed with three machine-learning algorithms, k nearest neighbors (kNN), random forest (RF), and support vector machine (SVM) regression, from a large pharmaceutical training set (~1000) and assessed with independent test sets of pharmaceuticals (~200) and environmentally relevant chemicals in the ToxCast program (~400). Small descriptor sets yielded the optimal balance of model complexity and performance, providing insight into the biochemical factors of plasma protein binding, while preventing over fitting to the training set. Overlaps in chemical space between pharmaceutical and environmental compounds were considered through applicability of do

Toxicity evaluations of various carbon nanomaterials.

PubMed

Uo, Motohiro; Akasaka, Tsukasa; Watari, Fumio; Sato, Yoshinori; Tohji, Kazuyuki

2011-01-01

After the discovery of fullerene and carbon nanotubes, various carbon nanomaterials were discovered or synthesized. The carbon nanomaterials have remarkable properties, different from bulk materials with the same chemical composition, and are therefore useful for industrial applications. However, the toxicity of nanomaterials may also differ from that of the bulk materials; this difference poses a concern. The physical similarity of nanomaterials to asbestos has led to evaluations for toxicity by many researchers using various methods. In this review, we compile and compare the toxicity evaluations of each carbon nanomaterial.

Chemical Composition of Aerosol from an E-Cigarette: A Quantitative Comparison with Cigarette Smoke.

PubMed

Margham, Jennifer; McAdam, Kevin; Forster, Mark; Liu, Chuan; Wright, Christopher; Mariner, Derek; Proctor, Christopher

2016-10-17

There is interest in the relative toxicities of emissions from electronic cigarettes and tobacco cigarettes. Lists of cigarette smoke priority toxicants have been developed to focus regulatory initiatives. However, a comprehensive assessment of e-cigarette chemical emissions including all tobacco smoke Harmful and Potentially Harmful Constituents, and additional toxic species reportedly present in e-cigarette emissions, is lacking. We examined 150 chemical emissions from an e-cigarette (Vype ePen), a reference tobacco cigarette (Ky3R4F), and laboratory air/method blanks. All measurements were conducted by a contract research laboratory using ISO 17025 accredited methods. The data show that it is essential to conduct laboratory air/method measurements when measuring e-cigarette emissions, owing to the combination of low emissions and the associated impact of laboratory background that can lead to false-positive results and overestimates. Of the 150 measurands examined in the e-cigarette aerosol, 104 were not detected and 21 were present due to laboratory background. Of the 25 detected aerosol constituents, 9 were present at levels too low to be quantified and 16 were generated in whole or in part by the e-cigarette. These comprised major e-liquid constituents (nicotine, propylene glycol, and glycerol), recognized impurities in Pharmacopoeia-quality nicotine, and eight thermal decomposition products of propylene glycol or glycerol. By contrast, approximately 100 measurands were detected in mainstream cigarette smoke. Depending on the regulatory list considered and the puffing regime used, the emissions of toxicants identified for regulation were from 82 to >99% lower on a per-puff basis from the e-cigarette compared with those from Ky3R4F. Thus, the aerosol from the e-cigarette is compositionally less complex than cigarette smoke and contains significantly lower levels of toxicants. These data demonstrate that e-cigarettes can be developed that offer the potential

Integrated modeling systems to assess exposure and toxicity of chemicals in support of aquatic ecological risk assessment of methodologically challenging chemicals

EPA Science Inventory

From an exposure assessment perspective, persistent, bioaccumulative and toxic chemicals (PBTs) are some of the most challenging chemicals facing environmental decision makers today. Due to their general physico-chemical properties [e.g., high octanol-water partition coefficien...

Toxic effects of chemical dispersant Corexit 9500 on water flea Daphnia magna.

PubMed

Toyota, Kenji; McNabb, Nicole A; Spyropoulos, Demetri D; Iguchi, Taisen; Kohno, Satomi

2017-02-01

In 2010, approximately 2.1 million gallons of chemical dispersants, mainly Corexit 9500, were applied in the Gulf of Mexico to prevent the oil slick from reaching shorelines and to accelerate biodegradation of oil during the Deepwater Horizon oil spill. Recent studies have revealed toxic effects of Corexit 9500 on marine microzooplankton that play important roles in food chains in marine ecosystems. However, there is still little known about the toxic effects of Corexit 9500 on freshwater zooplankton, even though oil spills do occur in freshwater and chemical dispersants may be used in response to these spills. The cladoceran crustacean, water flea Daphnia magna, is a well-established model species for various toxicological tests, including detection of juvenile hormone-like activity in test compounds. In this study, we conducted laboratory experiments to investigate the acute and chronic toxicity of Corexit 9500 using D. magna. The acute toxicity test was conducted according to OECD TG202 and the 48 h EC 50 was 1.31 ppm (CIs 0.99-1.64 ppm). The reproductive chronic toxicity test was performed following OECD TG211 ANNEX 7 and 21 days LOEC and NOEC values were 4.0 and 2.0 ppm, respectively. These results indicate that Corexit 9500 has toxic effects on daphnids, particularly during the neonatal developmental stage, which is consistent with marine zooplankton results, whereas juvenile hormone-like activity was not identified. Therefore, our findings of the adverse effects of Corexit 9500 on daphnids suggest that application of this type of chemical dispersant may have catastrophic impacts on freshwater ecosystems by disrupting the key food chain network. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

78 FR 64210 - Extension of Review Periods Under the Toxic Substances Control Act; Certain Chemicals and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-28

... Under the Toxic Substances Control Act; Certain Chemicals and Microorganisms; Premanufacture... 325 and 324110), e.g., chemical manufacturing and petroleum refineries. The North American Industrial... Agency under section 5 of the Toxic Substances Control Act (TSCA), received by EPA on or before October 1...

Application of fuzzy c-means clustering to PRTR chemicals uncovering their release and toxicity characteristics.

PubMed

Xue, Mianqiang; Zhou, Liang; Kojima, Naoya; Dos Muchangos, Leticia Sarmento; Machimura, Takashi; Tokai, Akihiro

2018-05-01

Increasing manufacture and usage of chemicals have not been matched by the increase in our understanding of their risks. Pollutant release and transfer register (PRTR) is becoming a popular measure for collecting chemical data and enhancing the public right to know. However, these data are usually in high dimensionality which restricts their wider use. The present study partitions Japanese PRTR chemicals into five fuzzy clusters by fuzzy c-mean clustering (FCM) to explore the implicit information. Each chemical with membership degrees belongs to each cluster. Cluster I features high releases from non-listed industries and the household sector and high environmental toxicity. Cluster II is characterized by high reported releases and transfers from 24 listed industries above the threshold, mutagenicity, and high environmental toxicity. Chemicals in cluster III have characteristics of high releases from non-listed industries and low toxicity. Cluster IV is characterized by high reported releases and transfers from 24 listed industries above the threshold and extremely high environmental toxicity. Cluster V is characterized by low releases yet mutagenicity and high carcinogenicity. Chemicals with the highest membership degree were identified as representatives for each cluster. For the highest membership degree, half of the chemicals have a value higher than 0.74. If we look at both the highest and the second highest membership degrees simultaneously, about 94% of the chemicals have a value higher than 0.5. FCM can serve as an approach to uncover the implicit information of highly complex chemical dataset, which subsequently supports the strategy development for efficient and effective chemical management. Copyright © 2017 Elsevier B.V. All rights reserved.

Toxicity and utilization of chemical weapons: does toxicity and venom utilization contribute to the formation of species communities?

PubMed

Westermann, Fabian L; McPherson, Iain S; Jones, Tappey H; Milicich, Lesley; Lester, Philip J

2015-08-01

Toxicity and the utilization of venom are essential features in the ecology of many animal species and have been hypothesized to be important factors contributing to the assembly of communities through competitive interactions. Ants of the genus Monomorium utilize a variety of venom compositions, which have been reported to give them a competitive advantage. Here, we investigate two pairs of Monomorium species, which differ in the structural compositions of their venom and their co-occurrence patterns with the invasive Argentine ant. We looked at the effects of Monomorium venom toxicity, venom utilization, and aggressive physical interactions on Monomorium and Argentine ant survival rates during arena trials. The venom toxicity of the two species co-occurring with the invasive Argentine ants was found to be significantly higher than the toxicity of the two species which do not. There was no correlation between venom toxicity and Monomorium survival; however, three of the four Monomorium species displayed significant variability in their venom usage which was associated with the number of Argentine ant workers encountered during trials. Average Monomorium mortality varied significantly between species, and in Monomorium smithii and Monomorium antipodum, aggressive interactions with Argentine ants had a significant negative effect on their mortality. Our study demonstrates that different factors and strategies can contribute to the ability of a species to withstand the pressure of a dominant invader at high abundance, and venom chemistry appears to be only one of several strategies utilized.

Estimating the Potential Toxicity of Chemicals Associated with Hydraulic Fracturing Operations Using Quantitative Structure-Activity Relationship Modeling

EPA Pesticide Factsheets

Researchers facilitated evaluation of chemicals that lack chronic oral toxicity values using a QSAR model to develop estimates of potential toxicity for chemicals used in HF fluids or found in flowback or produced water

The unsteady state and inertia of chemical regulation under the US Toxic Substances Control Act.

PubMed

Krimsky, Sheldon

2017-12-01

After 40 years, the 1976 US Toxic Substances Control Act (TSCA) was revised under the Frank R. Lautenberg Chemical Safety for the 21st Century Act. Its original goals of protecting the public from hazardous chemicals were hindered by complex and cumbersome administrative burdens, data limitations, vulnerabilities in risk assessments, and recurring corporate lawsuits. As a result, countless chemicals were entered into commercial use without toxicological information. Few chemicals of the many identified as potential public health threats were regulated or banned. This paper explores the factors that have worked against a comprehensive and rational policy for regulating toxic chemicals and discusses whether the TSCA revisions offer greater public protection against existing and new chemicals.

The unsteady state and inertia of chemical regulation under the US Toxic Substances Control Act

PubMed Central

2017-01-01

After 40 years, the 1976 US Toxic Substances Control Act (TSCA) was revised under the Frank R. Lautenberg Chemical Safety for the 21st Century Act. Its original goals of protecting the public from hazardous chemicals were hindered by complex and cumbersome administrative burdens, data limitations, vulnerabilities in risk assessments, and recurring corporate lawsuits. As a result, countless chemicals were entered into commercial use without toxicological information. Few chemicals of the many identified as potential public health threats were regulated or banned. This paper explores the factors that have worked against a comprehensive and rational policy for regulating toxic chemicals and discusses whether the TSCA revisions offer greater public protection against existing and new chemicals. PMID:29252997

Chemical, mechanical and biological properties of contemporary composite surface sealers.

PubMed

Anagnostou, Maria; Mountouris, George; Silikas, Nick; Kletsas, Dimitris; Eliades, George

2015-12-01

To evaluate the chemical, mechanical, and biological properties of modern composite surface sealers (CSS) having different compositions. The CSS products tested were Biscover LV (BC), Durafinish (DF), G-Coat Plus (GC), and Permaseal (PS). The tests performed were: (A): degree of conversion (DC%) by ATR-FTIR spectroscopy; (B): thickness of O2-inhibition layer by transmission optical microscopy; (C): surface hardness, 10 min after irradiation and following 1 week water storage, employing a Vickers indenter (VHN); (D): color (ΔE*) and gloss changes (ΔGU) after toothbrush abrasion, using L*a*b* colorimetry and glossimetry; (E): accelerated wear (GC,PS only) by an OHSU wear simulator plus 3D profilometric analysis, and (F): cytotoxicity testing of aqueous CSS eluents on human gingival fibroblast cultures employing the methyl-(3)H thymidine DNA labeling method. Statistical analyses included 1-way (A, B, ΔE*, ΔGU) and 2-way (C, F) ANOVAs, plus Tukey post hoc tests. Student's t-test was used to evaluate the results of the accelerated wear test (α=0.05 for all). The rankings of the statistical significant differences were: (A) PS (64.9)>DF,BC,GC (56.1-53.9) DC%; (B) DF,PS (12.3,9.8)>GC,BC (5.2,4.8) μm; (C): GC (37.6)>BC,DF (32.6,31.1)>PS (26.6) VHN (10 min/dry) and BC,DF (29.3,28.7)>GC(26.5)>PS(21.6) VHN (1w/water), with no significant material/storage condition interaction; (D): no differences were found among GC,DF,BC,PS (0.67-1.11) ΔE*, with all values within the visually acceptable range and PS,BC (32.8,29.4)>GC,DF (19.4,12.9) ΔGU; (E): no differences were found between GC and PS in volume loss (0.10,0.11 mm(3)), maximum (113.9,130.5 μm) and mean wear depths (30.3,27.5 μm); (F): at 1% v/v concentration, DF showed toxicity (23% vital cells vs 95-102% for others). However, at 5% v/v concentration DF (0%) and BC (9%) were the most toxic, whereas GC (58%) and PS (56%) showed moderate toxicity. Important chemical, mechanical, and biological properties exist among

Evaluating the Toxicity Pathways Using High-Throughput Environmental Chemical Data

EPA Science Inventory

The application of HTS methods to the characterization of human phenotypic response to environmental chemicals is a largely unexplored area of pharmacogenomics. The U.S. Environmental Protection Agency (EPA), through its ToxCast program, is developing predictive toxicity approach...

Prediction of the effect of formulation on the toxicity of chemicals.

PubMed

Mistry, Pritesh; Neagu, Daniel; Sanchez-Ruiz, Antonio; Trundle, Paul R; Vessey, Jonathan D; Gosling, John Paul

2017-01-01

Two approaches for the prediction of which of two vehicles will result in lower toxicity for anticancer agents are presented. Machine-learning models are developed using decision tree, random forest and partial least squares methodologies and statistical evidence is presented to demonstrate that they represent valid models. Separately, a clustering method is presented that allows the ordering of vehicles by the toxicity they show for chemically-related compounds.

Optical detection of chemical warfare agents and toxic industrial chemicals

NASA Astrophysics Data System (ADS)

Webber, Michael E.; Pushkarsky, Michael B.; Patel, C. Kumar N.

2004-12-01

We present an analytical model evaluating the suitability of optical absorption based spectroscopic techniques for detection of chemical warfare agents (CWAs) and toxic industrial chemicals (TICs) in ambient air. The sensor performance is modeled by simulating absorption spectra of a sample containing both the target and multitude of interfering species as well as an appropriate stochastic noise and determining the target concentrations from the simulated spectra via a least square fit (LSF) algorithm. The distribution of the LSF target concentrations determines the sensor sensitivity, probability of false positives (PFP) and probability of false negatives (PFN). The model was applied to CO2 laser based photoacosutic (L-PAS) CWA sensor and predicted single digit ppb sensitivity with very low PFP rates in the presence of significant amount of interferences. This approach will be useful for assessing sensor performance by developers and users alike; it also provides methodology for inter-comparison of different sensing technologies.

For Debate: Impotence in Farm Workers using Toxic Chemicals

PubMed Central

Espir, Michael L. E.; Hall, J. W.; Shirreffs, J. G.; Stevens, David L.

1970-01-01

Four out of five members of a team of farmworkers who had been using various herbicides and pesticides in intensive agriculture became impotent. Sexual function recovered after further contact with the chemicals was stopped and hormone therapy had been given, though in one case this took about a year. We have not been able to incriminate one particular substance, but with the circumstantial evidence and the lack of any other obvious cause it seems likely that the impotence was due to the toxic effects of one or more of the chemicals being used. PMID:5434665

Toxicity assessment of chlorpyrifos-degrading fungal bio-composites and their environmental risks.

PubMed

Liu, Jie; Zhang, Xiaoying; Yang, Mengran; Hu, Meiying; Zhong, Guohua

2018-02-01

Bioremediation techniques coupling with functional microorganisms have emerged as the most promising approaches for in-situ elimination of pesticide residue. However, the environmental safety of bio-products based on microorganisms or engineered enzymes was rarely known. Here, we described the toxicity assessment of two previously fabricated fungal bio-composites which were used for the biodegradation of chlorpyrifos, to clarify their potential risks on the environment and non-target organisms. Firstly, the acute and chronic toxicity of prepared bio-composites were evaluated using mice and rabbits, indicating neither acute nor chronic effect was induced via short-term or continuous exposure. Then, the acute mortality on zebrafish was investigated, which implied the application of fungal bio-composites had no lethal risk on aquatic organisms. Meanwhile, the assessment on soil organic matters suggested that no threat was posed to soil quality. Finally, by monitoring, the germination of cabbage was not affected by the exposure to two bio-products. Therefore, the application of fungal bio-composites for chlorpyrifos elimination cannot induce toxic risk to the environment and non-target organisms, which insured the safety of these engineered bio-products for realistic management of pesticide residue, and provided new insights for further development of bioremediation techniques based on functional microorganisms.

Antioxidants as potential medical countermeasures for chemical warfare agents and toxic industrial chemicals.

PubMed

McElroy, Cameron S; Day, Brian J

2016-01-15

The continuing horrors of military conflicts and terrorism often involve the use of chemical warfare agents (CWAs) and toxic industrial chemicals (TICs). Many CWA and TIC exposures are difficult to treat due to the danger they pose to first responders and their rapid onset that can produce death shortly after exposure. While the specific mechanism(s) of toxicity of these agents are diverse, many are associated either directly or indirectly with increased oxidative stress in affected tissues. This has led to the exploration of various antioxidants as potential medical countermeasures for CWA/TIC exposures. Studies have been performed across a wide array of agents, model organisms, exposure systems, and antioxidants, looking at an almost equally diverse set of endpoints. Attempts at treating CWAs/TICs with antioxidants have met with mixed results, ranging from no effect to nearly complete protection. The aim of this commentary is to summarize the literature in each category for evidence of oxidative stress and antioxidant efficacy against CWAs and TICs. While there is great disparity in the data concerning methods, models, and remedies, the outlook on antioxidants as medical countermeasures for CWA/TIC management appears promising. Copyright © 2015 Elsevier Inc. All rights reserved.

STRUCTURE-ACTIVITY RELATIONSHIP STUIDES AND THEIR ROLE IN PREDICTING AND INVESTIGATING CHEMICAL TOXICITY

EPA Science Inventory

Structure-Activity Relationship Studies and their Role in Predicting and Investigating Chemical Toxicity

Structure-activity relationships (SAR) represent attempts to generalize chemical information relative to biological activity for the twin purposes of generating insigh...

Chemical composition of stars in Ruprecht 106 .

NASA Astrophysics Data System (ADS)

François, P.

High resolution spectra of 9 stars belonging to the globular cluster Rup 106 have been used to determine their chemical composition. The results reveal that Ruprecht 106 exhibits abundance anomalies when compared to galactic globular cluster of similar metallicity. The chemical composition of these stars is similar to what is found in Dwarf spheroidal galaxies favoring the hypothesis that Rup 106 has not been formed in our Galaxy.

Toxicity Testing in the 21st Century Beyond Environmental Chemicals

PubMed Central

Rovida, Costanza; Asakura, Shoji; Daneshian, Mardas; Hofman-Huether, Hana; Leist, Marcel; Meunier, Leo; Reif, David; Rossi, Anna; Schmutz, Markus; Valentin, Jean-Pierre; Zurlo, Joanne; Hartung, Thomas

2018-01-01

Summary After the publication of the report titled Toxicity Testing in the 21st Century – A Vision and a Strategy, many initiatives started to foster a major paradigm shift for toxicity testing – from apical endpoints in animal-based tests to mechanistic endpoints through delineation of pathways of toxicity (PoT) in human cell based systems. The US EPA has funded an important project to develop new high throughput technologies based on human cell based in vitro technologies. These methods are currently being incorporated into the chemical risk assessment process. In the pharmaceutical industry, the efficacy and toxicity of new drugs are evaluated during preclinical investigations that include drug metabolism, pharmacokinetics, pharmacodynamics and safety toxicology studies. The results of these studies are analyzed and extrapolated to predict efficacy and potential adverse effects in humans. However, due to the high failure rate of drugs during the clinical phases, a new approach for a more predictive assessment of drugs both in terms of efficacy and adverse effects is getting urgent. The food industry faces the challenge of assessing novel foods and food ingredients for the general population, while using animal safety testing for extrapolation purposes is often of limited relevance. The question is whether the latest paradigm shift proposed by the Tox21c report for chemicals may provide a useful tool to improve the risk assessment approach also for drugs and food ingredients. PMID:26168280

The proposal of architecture for chemical splitting to optimize QSAR models for aquatic toxicity.

PubMed

Colombo, Andrea; Benfenati, Emilio; Karelson, Mati; Maran, Uko

2008-06-01

One of the challenges in the field of quantitative structure-activity relationship (QSAR) analysis is the correct classification of a chemical compound to an appropriate model for the prediction of activity. Thus, in previous studies, compounds have been divided into distinct groups according to their mode of action or chemical class. In the current study, theoretical molecular descriptors were used to divide 568 organic substances into subsets with toxicity measured for the 96-h lethal median concentration for the Fathead minnow (Pimephales promelas). Simple constitutional descriptors such as the number of aliphatic and aromatic rings and a quantum chemical descriptor, maximum bond order of a carbon atom divide compounds into nine subsets. For each subset of compounds the automatic forward selection of descriptors was applied to construct QSAR models. Significant correlations were achieved for each subset of chemicals and all models were validated with the leave-one-out internal validation procedure (R(2)(cv) approximately 0.80). The results encourage to consider this alternative way for the prediction of toxicity using QSAR subset models without direct reference to the mechanism of toxic action or the traditional chemical classification.

Lethal toxicity of industrial chemicals to early life stages of Tilapia guineensis.

PubMed

Ezemonye, L I N; Ogeleka, D F; Okieimen, F E

2008-08-30

The toxic effects of industrial chemicals on three early life stages of an economically important fish, Tilapia guineensis were investigated using the Organisation for Economic Cooperation and Development (OECD) # 203 recommended semi-static renewal bioassay. The assessment was necessary for the uncontrollable disposal of Neatex (liquid detergent) and Norust CR 486 (corrosion inhibitor) into the Niger Delta environment of Nigeria. The estimated 96-h LC(50) for 7-, 14- and 28-day-old fish in Norust CR 486 exposure was considered "more toxic" than Neatex in all life stages and was dependent on species age, exposure duration and environment. In the fresh water test, for Neatex and Norust CR 486 exposures for day 7, 14 and 28, the 96-h LC50 were 8.79, 17.10 and 82.42 mg/l and 5.55, 13.58 and 20.21 mg/l, respectively. In the brackish test, 15.42 and 46.52 mg/l, not determined (ND) and 7.35, 13.95 and 24.50mg/l were obtained. Differential toxicity was observed in the fresh and brackish water fish for the two chemicals and controls at p<0.05. The high sensitivity of the 7-day-old test organisms to both chemicals provides a rationale for regulatory surveillance and monitoring of both chemicals in the fragile Niger Delta environment.

Comparison among ultrasonic, electrical apparatus, and toxic chemicals for vestibular lesion in mice.

PubMed

Yamaoka, Yusuke; Abe, Chikara; Morita, Hironobu

2018-02-01

The vestibular lesion (VL) is required to examine the physiological function of the vestibular system in animals. Toxic chemicals or electrical apparatus have been used for the VL, however, they are not ideal as they have low specificity, and can result in unintended damage, and systemic toxic effect. Localized vibration-induced VL, using an ultrasonicator, is expected to overcome the problems associated with chemical and electrical lesions. Thus, we examined the effect of the ultrasonication on the VL from the aspects of both the physiological function and histology in the present study. and Comparison with Existing Method(s) Complete VL, which was evaluated by deterioration of swimming skills, righting reflex, and body stability, was induced using an ultrasonicator or electrical apparatus. Histological evaluation shows that hair cell layers in the saccule and utricle were completely destroyed in both methods Furthermore, significant drop in body mass was observed in VL. However, abscess at the cranial base was observed in VL induced by the electrical apparatus in ICR mice. Complete chemically-induced VL was observed in C57BL/6J but not ICR mice, and systemic leakage of the toxic chemicals (arsenic) was not detectable even 1day after surgery. Compared to the electrical apparatus, the ultrasonicator is useful for inducing VL in ICR and C57BL/6J mice, as it results in less non-specific damage. Toxic chemicals can be used for inducing VL in C57BL/6J mice; however, this method does not ensure complete disruption of the hair cells in the saccule and utricle. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Leachate composition and toxicity assessment: an integrated approach correlating physicochemical parameters and toxicity of leachates from MSW landfill in Delhi.

PubMed

Gupta, Anshu; Paulraj, R

2017-07-01

Landfills are considered the most widely practiced method for disposal of municipal solid waste (MSW) and 95% of the total MSW collected worldwide is disposed of in landfills. Leachate produced from MSW landfills may contain a number of pollutants and pose a potential environmental risk for surface as well as ground water. In the present study, chemical analysis and toxicity assessment of landfill leachate have been carried out. Leachate samples were collected from Ghazipur landfill site, New Delhi. Leachates were characterized by measuring the concentration of heavy metals (Pb, Cu, Cr and Ni), 5-day biochemical oxygen demand (BOD 5 ), chemical oxygen demand (COD), pH, electrical conductivity and SO 4 2 -. For toxicity testing of leachate, Triticum aestivum (wheat) was selected and testing was done in a time- and dose-dependent manner using the crude leachate. Median lethal concentration after 24 and 48 h of exposure was observed. The main objective of this study was to evaluate toxicity of MSW landfill leachate and establish a possible correlation between the measured physicochemical parameters and resultant toxicity. Statistical analysis showed that toxicity was dependent on the concentration of heavy metals (Pb, Cu), conductivity, and organic matter (COD and BOD5).

Physical and chemical characteristics of PM2.5 and its toxicity to human bronchial cells BEAS-2B in the winter and summer.

PubMed

Zhang, Hui-Hui; Li, Zheng; Liu, Yu; Xinag, Ping; Cui, Xin-Yi; Ye, Hui; Hu, Bao-Lan; Lou, Li-Ping

With the increasing occurrence of haze during the summer, the physicochemical characteristics and toxicity differences in PM 2.5 in different seasons are of great concern. Hangzhou is located in an area that has a subtropical monsoon climate where the humidity is very high during both the summer and winter. However, there are limited studies on the seasonal differences in PM 2.5 in these weather conditions. In this test, PM 2.5 samples were collected in the winter and summer, the morphology and chemical composition of PM 2.5 were analyzed, the toxicity of PM 2.5 to human bronchial cells BEAS-2B was compared, and the correlation between PM 2.5 toxicity and the chemical composition was discussed. The results showed that during both the winter and summer, the main compounds in the PM 2.5 samples were water-soluble ions, particularly SO 4 2- , NO 3 - , and NH 4 + , followed by organic components, while heavy metals were present at lower levels. The higher the mass concentration of PM 2.5 , the greater its impact on cell viability and ROS levels. However, when the mass concentration of PM 2.5 was similar, the water extraction from the summer samples showed a greater impact on BEAS-2B than that from the winter samples. The cytotoxicity of PM 2.5 was closely associated with heavy metals and organic pollutants but less related to water-soluble ions.

Including Bioconcentration Kinetics for the Prioritization and Interpretation of Regulatory Aquatic Toxicity Tests of Highly Hydrophobic Chemicals.

PubMed

Kwon, Jung-Hwan; Lee, So-Young; Kang, Hyun-Joong; Mayer, Philipp; Escher, Beate I

2016-11-01

Worldwide, regulations of chemicals require short-term toxicity data for evaluating hazards and risks of the chemicals. Current data requirements on the registration of chemicals are primarily based on tonnage and do not yet consider properties of chemicals. For example, short-term ecotoxicity data are required for chemicals with production volume greater than 1 or 10 ton/y according to REACH, without considering chemical properties. Highly hydrophobic chemicals are characterized by low water solubility and slow bioconcentration kinetics, which may hamper the interpretation of short-term toxicity experiments. In this work, internal concentrations of highly hydrophobic chemicals were predicted for standard acute ecotoxicity tests at three trophic levels, algae, invertebrate, and fish. As demonstrated by comparison with maximum aqueous concentrations at water solubility, chemicals with an octanol-water partition coefficient (K ow ) greater than 10 6 are not expected to reach sufficiently high internal concentrations for exerting effects within the test duration of acute tests with fish and invertebrates, even though they might be intrinsically toxic. This toxicity cutoff was explained by the slow uptake, i.e., by kinetics, not by thermodynamic limitations. Predictions were confirmed by data entries of the OECD's screening information data set (SIDS) (n = 746), apart from a few exceptions concerning mainly organometallic substances and those with inconsistency between water solubility and K ow . Taking error propagation and model assumptions into account, we thus propose a revision of data requirements for highly hydrophobic chemicals with log K ow > 7.4: Short-term toxicity tests can be limited to algae that generally have the highest uptake rate constants, whereas the primary focus of the assessment should be on persistence, bioaccumulation, and long-term effects.

Variation in chemical composition and allelopathic potential of mixoploid Trigonella foenum-graecum L. with developmental stages.

PubMed

Omezzine, Faten; Bouaziz, Mohamed; Simmonds, Monique S J; Haouala, Rabiaa

2014-04-01

This study was conducted to evaluate the influence of developmental stages (vegetative, flowering and fruiting) of mixoploid fenugreek aerial parts on their chemical composition and allelopathic potential, assessed on lettuce germination and seedling growth. Aqueous and organic extracts significantly delayed germination, reduced its rate and affected seedling growth. Ethyl acetate and methanol extracts of aerial parts harvested at vegetative stage were the most toxic for lettuce germination and seedling growth, respectively. LC-MS/MS analysis of T. foenum-graecum aerial parts methanolic extract showed nine different flavonol glycosides (quercetin and kaempferol glucosides). Chemical composition of aerial parts differed with the developmental stage; indeed, at the vegetative and fruiting stages, analysis revealed the presence of 9 compounds as compared to only 6 compounds at the flowering stage. Thus, it is necessary to follow the qualitative changes of allelochemicals production at different developmental stages to identify the most productive one. Copyright © 2013 Elsevier Ltd. All rights reserved.

New Chemicals Exposure Limits section 5(e) Order Boilerplate insert under the Toxic Substances Control Act (TSCA) New Chemicals Program

EPA Pesticide Factsheets

The New Chemicals Exposure Limits (NCELs) section 5(e) Consent Order insert presents the standard NCELs provisions. The actual NCEL concentration is an empty blank to be completed depending on the toxicity of the specific chemical involved.

Detection of toxic industrial chemicals in water supplies using surface-enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Spencer, Kevin M.; Sylvia, James M.; Spencer, Sarah A.; Clauson, Susan L.

2010-04-01

An effective method to create fear in the populace is to endanger the water supply. Homeland Security places significant importance on ensuring drinking water integrity. Beyond terrorism, accidental supply contamination from a spill or chemical residual increases is a concern. A prominent class of toxic industrial chemicals (TICs) is pesticides, which are prevalent in agricultural use and can be very toxic in minute concentrations. Detection of TICs or warfare agents must be aggressive; the contaminant needs to be rapidly detected and identified to enable isolation and remediation of the contaminated water while continuing a clean water supply for the population. Awaiting laboratory analysis is unacceptable as delay in identification and remediation increases the likelihood of infection. Therefore, a portable or online water quality sensor is required that can produce rapid results. In this presentation, Surface-Enhanced Raman Spectroscopy (SERS) is discussed as a viable fieldable sensor that can be immersed directly into the water supply and can provide results in <5 minutes from the time the instrument is turned on until analysis is complete. The ability of SERS to detect several chemical warfare agent degradation products, simulants and toxic industrial chemicals in distilled water, tap water and untreated water will be shown. In addition, results for chemical warfare agent degradation products and simulants will be presented. Receiver operator characteristic (ROC) curves will also be presented.

Integration of Dosimetry, Exposure and High-Throughput Screening Data in Chemical Toxicity Assessment

EPA Science Inventory

High-throughput in vitro toxicity screening can provide an efficient way to identify potential biological targets for chemicals. However, relying on nominal assay concentrations may misrepresent potential in vivo effects of these chemicals due to differences in bioavailability, c...

Brand switching and toxic chemicals in cigarette smoke: A national study.

PubMed

Mendel, Jennifer R; Baig, Sabeeh A; Hall, Marissa G; Jeong, Michelle; Byron, M Justin; Morgan, Jennifer C; Noar, Seth M; Ribisl, Kurt M; Brewer, Noel T

2018-01-01

US law requires disclosure of quantities of toxic chemicals (constituents) in cigarette smoke by brand and sub-brand. This information may drive smokers to switch to cigarettes with lower chemical quantities, under the misperception that doing so can reduce health risk. We sought to understand past brand-switching behavior and whether learning about specific chemicals in cigarette smoke increases susceptibility to brand switching. Participants were US adult smokers surveyed by phone (n = 1,151, probability sample) and online (n = 1,561, convenience sample). Surveys assessed whether smokers had ever switched cigarette brands or styles to reduce health risk and about likelihood of switching if the smoker learned their brand had more of a specific chemical than other cigarettes. Chemicals presented were nicotine, carbon monoxide, lead, formaldehyde, arsenic, and ammonia. Past brand switching to reduce health risk was common among smokers (43% in phone survey, 28% in online survey). Smokers who were female, over 25, and current "light" cigarette users were more likely to have switched brands to reduce health risks (all p < .05). Overall, 61-92% of smokers were susceptible to brand switching based on information about particular chemicals. In both samples, lead, formaldehyde, arsenic, and ammonia led to more susceptibility to switch than nicotine (all p < .05). Many US smokers have switched brands or styles to reduce health risks. The majority said they might or would definitely switch brands if they learned their cigarettes had more of a toxic chemical than other brands. Brand switching is a probable unintended consequence of communications that show differences in smoke chemicals between brands.

Toxicity assessment of industrial chemicals and airborne contaminants: transition from in vivo to in vitro test methods: a review.

PubMed

Bakand, S; Winder, C; Khalil, C; Hayes, A

2005-12-01

Exposure to occupational and environmental contaminants is a major contributor to human health problems. Inhalation of gases, vapors, aerosols, and mixtures of these can cause a wide range of adverse health effects, ranging from simple irritation to systemic diseases. Despite significant achievements in the risk assessment of chemicals, the toxicological database, particularly for industrial chemicals, remains limited. Considering there are approximately 80,000 chemicals in commerce, and an extremely large number of chemical mixtures, in vivo testing of this large number is unachievable from both economical and practical perspectives. While in vitro methods are capable of rapidly providing toxicity information, regulatory agencies in general are still cautious about the replacement of whole-animal methods with new in vitro techniques. Although studying the toxic effects of inhaled chemicals is a complex subject, recent studies demonstrate that in vitro methods may have significant potential for assessing the toxicity of airborne contaminants. In this review, current toxicity test methods for risk evaluation of industrial chemicals and airborne contaminants are presented. To evaluate the potential applications of in vitro methods for studying respiratory toxicity, more recent models developed for toxicity testing of airborne contaminants are discussed.

Chemical composition, toxicity and non-target effects of Pinus kesiya essential oil: An eco-friendly and novel larvicide against malaria, dengue and lymphatic filariasis mosquito vectors.

PubMed

Govindarajan, Marimuthu; Rajeswary, Mohan; Benelli, Giovanni

2016-07-01

Mosquitoes (Diptera: Culicidae) are vectors of important parasites and pathogens causing death, poverty and social disability worldwide, with special reference to tropical and subtropical countries. The overuse of synthetic insecticides to control mosquito vectors lead to resistance, adverse environmental effects and high operational costs. Therefore, the development of eco-friendly control tools is an important public health challenge. In this study, the mosquito larvicidal activity of Pinus kesiya leaf essential oil (EO) was evaluated against the malaria vector Anopheles stephensi, the dengue vector Aedes aegypti and the lymphatic filariasis vector Culex quinquefasciatus. The chemical composition of the EO was analyzed by gas chromatography-mass spectroscopy. GC-MS revealed that the P. kesiya EO contained 18 compounds. Major constituents were α-pinene, β-pinene, myrcene and germacrene D. In acute toxicity assays, the EO showed significant toxicity against early third-stage larvae of An. stephensi, Ae. aegypti and Cx. quinquefasciatus, with LC50 values of 52, 57, and 62µg/ml, respectively. Notably, the EO was safer towards several aquatic non-target organisms Anisops bouvieri, Diplonychus indicus and Gambusia affinis, with LC50 values ranging from 4135 to 8390µg/ml. Overall, this research adds basic knowledge to develop newer and safer natural larvicides from Pinaceae plants against malaria, dengue and filariasis mosquito vectors. Copyright © 2016 Elsevier Inc. All rights reserved.

The U.S. Environmental Protection Agency strategic plan for evaluating the toxicity of chemicals.

PubMed

Firestone, Michael; Kavlock, Robert; Zenick, Hal; Kramer, Melissa

2010-02-01

In the 2007 report Toxicity Testing in the 21st Century: A Vision and a Strategy, the U.S. National Academy of Sciences envisioned a major transition in toxicity testing from cumbersome, expensive, and lengthy in vivo testing with qualitative endpoints, to in vitro robotic high-throughput screening with mechanistic quantitative parameters. Recognizing the need for agencies to partner and collaborate to ensure global harmonization, standardization, quality control and information sharing, the U.S. Environmental Protection Agency is leading by example and has established an intra-agency Future of Toxicity Testing Workgroup (FTTW). This workgroup has produced an ambitious blueprint for incorporating this new scientific paradigm to change the way chemicals are screened and evaluated for toxicity. Four main components of this strategy are discussed, as follows: (1) the impact and benefits of various types of regulatory activities, (2) chemical screening and prioritization, (3) toxicity pathway-based risk assessment, and (4) institutional transition. The new paradigm is predicated on the discovery of molecular perturbation pathways at the in vitro level that predict adverse health effects from xenobiotics exposure, and then extrapolating those events to the tissue, organ, or whole organisms by computational models. Research on these pathways will be integrated and compiled using the latest technology with the cooperation of global agencies, industry, and other stakeholders. The net result will be that chemical toxicity screening will become more efficient and cost-effective, include real-world exposure assessments, and eliminate currently used uncertainty factors.

Toxicity and chemical analyses of airport runoff waters in Poland.

PubMed

Sulej, Anna Maria; Polkowska, Zaneta; Wolska, Lidia; Cieszynska, Monika; Namieśnik, Jacek

2014-05-01

The aim of this study was to assess the ecotoxicological effects of various compounds in complex airport effluents using a chemical and ecotoxicological integrated strategy. The present work deals with the determination of sum of PCBs, PAHs, pesticides, cations, anions, phenols, anionic, cationic, non-ionic detergents, formaldehyde and metals--as well as TOC and conductivity--in runoff water samples collected from 2009 to 2011 at several locations on two Polish international airports. Two microbiotests (Vibrio fischeri bacteria and the crustacean Thamnocephalus platyurus) have been used to determine the ecotoxicity of airport runoff waters. The levels of many compounds exceeded several or even several tens of times the maximum permissible levels. Analysis of the obtained data shows that samples that displayed maximum toxicity towards the bioindicators Vibrio fischeri were not toxic towards Thamnocephalus platyurus. Levels of toxicity towards T. platyurus are strongly correlated with pollutants that originate from the technological operations related to the maintenance of airport infrastructure. The integrated (chemical-ecotoxicological) approach to environmental contamination assessment in and around airports yields extensive information on the quality of the environment. These methodologies can be then used as tools for tracking the environmental fate of these compounds and for assessing the environmental effect of airports. Subsequently, these data will provide a basis for airport infrastructure management.

Acute oral toxicity of chemicals in terrestrial life stages of amphibians: Comparisons to birds and mammals.

PubMed

Crane, Mark; Finnegan, Meaghean; Weltje, Lennart; Kosmala-Grzechnik, Sylwia; Gross, Melanie; Wheeler, James R

2016-10-01

Amphibians are currently the most threatened and rapidly declining group of vertebrates and this has raised concerns about their potential sensitivity and exposure to plant protection products and other chemicals. Current environmental risk assessment procedures rely on surrogate species (e.g. fish and birds) to cover the risk to aquatic and terrestrial life stages of amphibians, respectively. Whilst a recent meta-analysis has shown that in most cases amphibian aquatic life stages are less sensitive to chemicals than fish, little research has been conducted on the comparative sensitivity of terrestrial amphibian life stages. Therefore, in this paper we address the questions "What is the relative sensitivity of terrestrial amphibian life stages to acute chemical oral exposure when compared with mammals and birds?" and "Are there correlations between oral toxicity data for amphibians and data for mammals or birds?" Identifying a relationship between these data may help to avoid additional vertebrate testing. Acute oral amphibian toxicity data collected from the scientific literature and ecotoxicological databases were compared with toxicity data for mammals and birds. Toxicity data for terrestrial amphibian life stages are generally sparse, as noted in previous reviews. Single-dose oral toxicity data for terrestrial amphibian life stages were available for 26 chemicals and these were positively correlated with LD50 values for mammals, while no correlation was found for birds. Further, the data suggest that oral toxicity to terrestrial amphibian life stages is similar to or lower than that for mammals and birds, with a few exceptions. Thus, mammals or birds are considered adequate toxicity surrogates for use in the assessment of the oral exposure route in amphibians. However, there is a need for further data on a wider range of chemicals to explore the wider applicability of the current analyses and recommendations. Copyright © 2016 Elsevier Inc. All rights reserved.

Children's vulnerability to toxic chemicals: a challenge and opportunity to strengthen health and environmental policy.

PubMed

Landrigan, Philip J; Goldman, Lynn R

2011-05-01

A key policy breakthrough occurred nearly twenty years ago with the discovery that children are far more sensitive than adults to toxic chemicals in the environment. This finding led to the recognition that chemical exposures early in life are significant and preventable causes of disease in children and adults. We review this knowledge and recommend a new policy to regulate industrial and consumer chemicals that will protect the health of children and all Americans, prevent disease, and reduce health care costs. The linchpins of a new US chemical policy will be: first, a legally mandated requirement to test the toxicity of chemicals already in commerce, prioritizing chemicals in the widest use, and incorporating new assessment technologies; second, a tiered approach to premarket evaluation of new chemicals; and third, epidemiologic monitoring and focused health studies of exposed populations.

Chemical composition, antimicrobial properties and toxicity evaluation of the essential oil of Cupressus lusitanica Mill. leaves from Cameroon.

PubMed

Teke, Gerald Ngo; Elisée, Kemadjou Nana; Roger, Kuiate Jules

2013-06-13

The leaves of Cupressus lusitanica Mill. are used in the western highlands of Cameroon for their medicinal property. The leaves of this species were collected in the West Region of Cameroon in August 2010 and subjected to hydrodistillation to obtain the essential oil. The oil was fractionated using adsorption column chromatography. The chemical composition of this oil and its fractions was analysed by gas chromatography-mass spectrometry (GC-MS). The essential oil and fractions were tested for antimicrobial activity against eight bacterial species and six species of Candida by the agar diffusion method. Macrodilution method was used to determine the minimum inhibition concentrations (MICs) and minimum bactericidal and/or fungicidal concentrations (MBCs and MFCs). The toxicity profile of the oil was studied using Swiss mice and Wistar albino rats. Forty-nine compounds were identified in the essential oil. The main components were germacrene D (18.5%), epi-zonarene (8.2%), cis-calamenene (8.2%), terpinen-4-ol (6.3%), linalool (6.0%) and umbellulone (6.0%). Enterococcus faecalis, Proteus mirabilis and Candida albicans were most susceptible to the oil (MICs of 1.25 and 0.16% for bacteria and fungi respectively). The estimated oral LD50 was 6.33 g/kg. There was an increase in sera ALT and AST activities while the blood cells and protein levels decreased in treated animals. The results obtained from this study support the ethnomedicinal use of C. lusitanica leaf oil in the treatment of whooping cough and skin infections though it should be used with care. This plant oil could be useful in the standardisation of phytomedicine.

QUANTITATIVE STRUCTURE ACTIVITY RELATIONSHIP (QSAR) MODELS TO PREDICT CHEMICAL TOXICITY FOR VARIOUS HEALTH ENDPOINTS

EPA Science Inventory

Although ranking schemes based on exposure and toxicity have been developed to aid in the prioritization of research funds for identifying chemicals of regulatory concern, there are significant gaps in the availability of experimental toxicity data for most health endpoints. Pred...

A Workflow for Identifying Metabolically Active Chemicals to Complement in vitro Toxicity Screening

EPA Science Inventory

The new paradigm of toxicity testing approaches involves rapid screening of thousands of chemicals across hundreds of biological targets through use of in vitro assays. Such assays may lead to false negatives when the complex metabolic processes that render a chemical bioactive i...

Use of statistical and neural net approaches in predicting toxicity of chemicals.

PubMed

Basak, S C; Grunwald, G D; Gute, B D; Balasubramanian, K; Opitz, D

2000-01-01

Hierarchical quantitative structure-activity relationships (H-QSAR) have been developed as a new approach in constructing models for estimating physicochemical, biomedicinal, and toxicological properties of interest. This approach uses increasingly more complex molecular descriptors in a graduated approach to model building. In this study, statistical and neural network methods have been applied to the development of H-QSAR models for estimating the acute aquatic toxicity (LC50) of 69 benzene derivatives to Pimephales promelas (fathead minnow). Topostructural, topochemical, geometrical, and quantum chemical indices were used as the four levels of the hierarchical method. It is clear from both the statistical and neural network models that topostructural indices alone cannot adequately model this set of congeneric chemicals. Not surprisingly, topochemical indices greatly increase the predictive power of both statistical and neural network models. Quantum chemical indices also add significantly to the modeling of this set of acute aquatic toxicity data.

Toxic Substances Registry System Index of Material Safety Data Sheets

NASA Technical Reports Server (NTRS)

1997-01-01

The July 1997 revision of the Index of Material Safety Data Sheets (MSDS) for the Kennedy Space Center (KSC) Toxic Substances Registry System (TSRS) is presented. The MSDS lists toxic substances by manufacturer, trade name, stock number, and distributor. The index provides information on hazards, use, and chemical composition of materials stored at KSC.

Application of Solid Phase Microextraction Coupled with Gas Chromatography/Mass Spectrometry as a Rapid Method for Field Sampling and Analysis of Chemical Warfare Agents and Toxic Industrial Chemicals

DTIC Science & Technology

2003-01-01

PHASE MICROEXTRACTION COUPLED WITH GAS CHROMATOGRAPHY/MASS SPECTROMETRY AS A RAPID METHOD FOR FIELD SAMPLING AND ANALYSIS OF CHEMICAL WARFARE AGENTS...SAMPLING AND ANALYSIS OF CHEMICAL WARFARE AGENTS AND TOXIC INDUSTRIAL CHEMICALS 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...GAS CHROMATOGRAPHY/MASS SPECTROMETRY AS A RAPID METHOD FOR FIELD SAMPLING AND ANALYSIS OF CHEMICAL WARFARE AGENTS AND TOXIC INDUSTRIAL CHEMICALS

Atomic charges of individual reactive chemicals in binary mixtures determine their joint effects: an example of cyanogenic toxicants and aldehydes.

PubMed

Tian, Dayong; Lin, Zhifen; Yin, Daqiang; Zhang, Yalei; Kong, Deyang

2012-02-01

Environmental contaminants are usually encountered as mixtures, and many of these mixtures yield synergistic or antagonistic effects attributable to an intracellular chemical reaction that pose a potential threat on ecological systems. However, how atomic charges of individual chemicals determine their intracellular chemical reactions, and then determine the joint effects for mixtures containing reactive toxicants, is not well understood. To address this issue, the joint effects between cyanogenic toxicants and aldehydes on Photobacterium phosphoreum were observed in the present study. Their toxicological joint effects differed from one another. This difference is inherently related to the two atomic charges of the individual chemicals: the oxygen charge of -CHO (O(aldehyde toxicant)) in aldehyde toxicants and the carbon-atom charge of a carbon chain in the cyanogenic toxicant (C(cyanogenic toxicant)). Based on these two atomic charges, the following QSAR (quantitative structure-activity relationship) model was proposed: When (O(aldehyde toxicant) -C(cyanogenic toxicant) )> -0.125, the joint effect of equitoxic binary mixtures at median inhibition (TU, the sum of toxic units) can be calculated as TU = 1.00 ± 0.20; when (O(aldehyde toxicant) -C(cyanogenic toxicant) ) ≤ -0.125, the joint effect can be calculated using TU = - 27.6 x O (aldehyde toxicant) - 5.22 x C (cyanogenic toxicant) - 6.97 (n = 40, r = 0.887, SE = 0.195, F = 140, p < 0.001, q(2) (Loo) = 0.748; SE is the standard error of the regression, F is the F test statistic). The result provides insight into the relationship between the atomic charges and the joint effects for mixtures containing cyanogenic toxicants and aldehydes. This demonstrates that the essence of the joint effects resulting from intracellular chemical reactions depends on the atomic charges of individual chemicals. The present study provides a possible approach for the development of a QSAR model for mixtures containing reactive

Predicting acute aquatic toxicity of structurally diverse chemicals in fish using artificial intelligence approaches.

PubMed

Singh, Kunwar P; Gupta, Shikha; Rai, Premanjali

2013-09-01

The research aims to develop global modeling tools capable of categorizing structurally diverse chemicals in various toxicity classes according to the EEC and European Community directives, and to predict their acute toxicity in fathead minnow using set of selected molecular descriptors. Accordingly, artificial intelligence approach based classification and regression models, such as probabilistic neural networks (PNN), generalized regression neural networks (GRNN), multilayer perceptron neural network (MLPN), radial basis function neural network (RBFN), support vector machines (SVM), gene expression programming (GEP), and decision tree (DT) were constructed using the experimental toxicity data. Diversity and non-linearity in the chemicals' data were tested using the Tanimoto similarity index and Brock-Dechert-Scheinkman statistics. Predictive and generalization abilities of various models constructed here were compared using several statistical parameters. PNN and GRNN models performed relatively better than MLPN, RBFN, SVM, GEP, and DT. Both in two and four category classifications, PNN yielded a considerably high accuracy of classification in training (95.85 percent and 90.07 percent) and validation data (91.30 percent and 86.96 percent), respectively. GRNN rendered a high correlation between the measured and model predicted -log LC50 values both for the training (0.929) and validation (0.910) data and low prediction errors (RMSE) of 0.52 and 0.49 for two sets. Efficiency of the selected PNN and GRNN models in predicting acute toxicity of new chemicals was adequately validated using external datasets of different fish species (fathead minnow, bluegill, trout, and guppy). The PNN and GRNN models showed good predictive and generalization abilities and can be used as tools for predicting toxicities of structurally diverse chemical compounds. Copyright © 2013 Elsevier Inc. All rights reserved.

Toxicity testing of chemical mixtures: some general aspects and need of international guidelines.

PubMed

Kappus, H; Yang, R S

1996-01-01

The topics discussed by the Working Group on Toxicity Testing of Chemical Mixtures included the following (1) the study designs and results from two real-life exposure scenarios as additional information to the various investigations reported at the conference; (2) the need to take into consideration low-level, long-term exposure (i.e. mimicking human exposure conditions) as well as the issue of limited resources in experimental toxicology studies; (3) the importance of exploring alternative and predictive toxicology methodologies to minimize animal use and to conserve resources; (4) the realization that interactive toxicity should include the consideration of physical and biological agents in addition to chemicals. Two specific studies reported at the conference were also discussed. A number of recommendations were made concerning the planning and implementation of toxicology studies on chemical mixtures.

Cometary coma chemical composition (C4) mission. [Abstract only

NASA Technical Reports Server (NTRS)

Carle, G. C.; Clark, B. C.; Niemann, H. B.; Alexander, M.; Knocke, P. C.; O'Hara, B. J.

1994-01-01

Cometary missions are of enormous fundamental importance for many different space science disciplines, including exobiology. Comets are presumed relics of the earliest, most primitive material in the solar nebula and are related to the planetesimals. They undoubtedly provided a general enrichment of volatiles to the inner solar system (contributing to atmospheres and oceans) and may have been key to the origin of life. A Discovery class, comet rendezvous mission, the Cometary Coma Chemical Composition (C4) Mission, was selected for further study by NASA earlier this year. The C4 Mission is a highly focused and usefully-limited subset of the Cometary Rendezvous Asteroid Flyby (CRAF) Mission, concentrating exclusively on measurements which will lead to an understanding of the chemical composition and make-up of the cometary nucleus. The scientific goals of the Cometary Coma Chemical Composition (C4) Mission are to rendezvous with a short-period comet and (1) to determine the elemental, chemical, and isotopic composition of the nucleus and (2) to characterize the chemical and isotopic nature of its atmosphere. Further, it is a goal to obtain preliminary data on the development of the coma (dust and gas composition) as a function of time and orbital position.

Tox21 Enricher: Web-based Chemical/Biological Functional Annotation Analysis Tool Based on Tox21 Toxicity Screening Platform.

PubMed

Hur, Junguk; Danes, Larson; Hsieh, Jui-Hua; McGregor, Brett; Krout, Dakota; Auerbach, Scott

2018-05-01

The US Toxicology Testing in the 21st Century (Tox21) program was established to develop more efficient and human-relevant toxicity assessment methods. The Tox21 program screens >10,000 chemicals using quantitative high-throughput screening (qHTS) of assays that measure effects on toxicity pathways. To date, more than 70 assays have yielded >12 million concentration-response curves. The patterns of activity across assays can be used to define similarity between chemicals. Assuming chemicals with similar activity profiles have similar toxicological properties, we may infer toxicological properties based on its neighbourhood. One approach to inference is chemical/biological annotation enrichment analysis. Here, we present Tox21 Enricher, a web-based chemical annotation enrichment tool for the Tox21 toxicity screening platform. Tox21 Enricher identifies over-represented chemical/biological annotations among lists of chemicals (neighbourhoods), facilitating the identification of the toxicological properties and mechanisms in the chemical set. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical composition of Mars

NASA Technical Reports Server (NTRS)

Morgan, J. W.; Anders, E.

1979-01-01

The chemical composition of Mars is estimated from the cosmochemical model of Ganapathy and Anders (1974) with additional petrological and geophysical constraints. The model assumes that planets and chondrites underwent the same fractionation processes in the solar nebula, and constraints are imposed by the abundance of the heat-producing elements, U, Th and K, the volatile-rich component and the high density of the mantle. Global abundances of 83 elements are presented, and it is noted that the mantle is an iron-rich garnet wehrlite, nearly identical to the bulk moon composition of Morgan at al. (1978) and that the core is sulfur poor (3.5% S). The comparison of model compositions for the earth, Venus, Mars, the moon and a eucrite parent body suggests that volatile depletion correlates mainly with size rather than with radial distance from the sun.

78 FR 66700 - Toxic Substances Control Act Chemical Testing; Receipt of Test Data

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-06

... Chemical Testing; Receipt of Test Data AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: This notice announces EPA's receipt of test data on 21 chemicals. These data were submitted pursuant to 3 test rules issued by EPA under section 4 of the Toxic Substance Control Act (TSCA). The...

Controls on the chemical composition of saline surface crusts and emitted dust from a wet playa in the Mojave Desert (USA)

USGS Publications Warehouse

Goldstein, Harland L.; Breit, George N.; Reynolds, Richard L.

2017-01-01

Saline-surface crusts and their compositions at ephemeral, dry, and drying lakes are important products of arid-land processes. Detailed understanding is lacking, however, about interactions among locally variable hydrogeologic conditions, compositional control of groundwater on vadose zone and surface salts, and dust composition. Chemical and physical data from groundwater, sediments, and salts reveal compositional controls on saline-surface crusts across a wet playa, Mojave Desert, with bearing on similar settings elsewhere. The compositions of chemically and isotopically distinctive shallow (<3 m) water masses are recorded in the composition of associated salts. In areas with deeper and more saline groundwater, however, not all ions are transported through the vadose zone. Retention of arsenic and other elements in the vadose zone diminishes the concentrations of potentially toxic elements in surface salts, but creates a reservoir of these elements that may be brought to the surface during wetter conditions or by human disturbance. Selective wind-erosion loss of sulfate salts was identified by the compositional contrast between surface salt crusts and underlying groundwater. At the sub-basin scale, compositional links exist among groundwater, salt crusts, and dust from wet playas. Across the study basin, however, lateral variations in groundwater and solid-salt compositions are produced by hydrogeologic heterogeneity.

Effective Strategies for Monitoring and Regulating Chemical Mixtures and Contaminants Sharing Pathways of Toxicity

PubMed Central

Venkatesan, Arjun K.; Halden, Rolf U.

2015-01-01

Traditionally, hazardous chemicals have been regulated in the U.S. on a one-by-one basis, an approach that is slow, expensive and can be inefficient, as illustrated by a decades-long succession of replacing one type of organohalogen flame retardants (OHFRs) with another one, without addressing the root cause of toxicity and associated public health threats posed. The present article expounds on the need for efficient monitoring strategies and pragmatic steps in reducing environmental pollution and adverse human health impacts. A promising approach is to combine specific bioassays with state-of-the-art chemical screening to identify chemicals and chemical mixtures sharing specific modes of action (MOAs) and pathways of toxicity (PoTs). This approach could be used to identify and regulate hazardous chemicals as classes or compound families, featuring similar biological end-points, such as endocrine disruption and mutagenicity. Opportunities and potential obstacles of implementing this approach are discussed. PMID:26343697

Oral LD50 toxicity modeling and prediction of per- and polyfluorinated chemicals on rat and mouse.

PubMed

Bhhatarai, Barun; Gramatica, Paola

2011-05-01

Quantitative structure-activity relationship (QSAR) analyses were performed using the LD(50) oral toxicity data of per- and polyfluorinated chemicals (PFCs) on rodents: rat and mouse. PFCs are studied under the EU project CADASTER which uses the available experimental data for prediction and prioritization of toxic chemicals for risk assessment by using the in silico tools. The methodology presented here applies chemometrical analysis on the existing experimental data and predicts the toxicity of new compounds. QSAR analyses were performed on the available 58 mouse and 50 rat LD(50) oral data using multiple linear regression (MLR) based on theoretical molecular descriptors selected by genetic algorithm (GA). Training and prediction sets were prepared a priori from available experimental datasets in terms of structure and response. These sets were used to derive statistically robust and predictive (both internally and externally) models. The structural applicability domain (AD) of the models were verified on 376 per- and polyfluorinated chemicals including those in REACH preregistration list. The rat and mouse endpoints were predicted by each model for the studied compounds, and finally 30 compounds, all perfluorinated, were prioritized as most important for experimental toxicity analysis under the project. In addition, cumulative study on compounds within the AD of all four models, including two earlier published models on LC(50) rodent analysis was studied and the cumulative toxicity trend was observed using principal component analysis (PCA). The similarities and the differences observed in terms of descriptors and chemical/mechanistic meaning encoded by descriptors to prioritize the most toxic compounds are highlighted.

Toxic Substances Registry System: Index of Material Safety Data Sheets. Revised

NASA Technical Reports Server (NTRS)

1998-01-01

The January 1998 revision of the Index of Materials Safety Data Sheets (MSDS) for the Kennedy Space Center (KSC) Toxic Substances Registry System (TSRS) is presented. The MSDS lists toxic substances by manufacturer, trade name, stock number, and distributor. The index provides information on hazards, use, and chemical composition of materials stored at KSC.

TOXICOGENOMIC STUDY OF TRIAZOLE FUNGICIDES AND PERFLUOROALKYL ACIDS IN RAT LIVERS ACCURATELY CATEGORIZES CHEMICALS AND IDENTIFIES MECHANISMS OF TOXICITY

EPA Science Inventory

Toxicogenomic analysis of five environmental chemicals was performed to investigate the ability of genomics to predict toxicity, categorize chemicals, and elucidate mechanisms of toxicity. Three triazole antifungals (myclobutanil, propiconazole, and triadimefon) and two perfluori...

CHEMICAL CONTAMINATION AND TOXICITY ASSOCIATED WITH A COASTAL GOLF COURSE COMPLEX

EPA Science Inventory

The increasing density of golf courses represents a potential source of contamination to nearby coastal areas, the chemical and biological magnitude of which is almost unknown. The objective of this study was to compare the concentrations of contaminants and toxicities of sedime...

Chemical composition and larvicidal activity of essential oil from Ocimum basilicum (L.) against Culex tritaeniorhynchus, Aedes albopictus and Anopheles subpictus (Diptera: Culicidae).

PubMed

Govindarajan, M; Sivakumar, R; Rajeswary, M; Yogalakshmi, K

2013-05-01

The toxicity of mosquito larvicidal activity of leaf essential oil and their major chemical constituents from Ocimum basilicum were evaluated against Culex tritaeniorhynchus, Aedes albopictus and Anopheles subpictus. The chemical composition of the leaf essential oil was analyzed using gas chromatography-mass spectroscopy. GC-MS revealed that the essential oil of O. basilicum contained 20 compounds. The major chemical components identified were linalool (52.42%), methyl eugenol (18.74%) and 1, 8-cineol (5.61%). The essential oil had a significant toxic effect against late third-stage larvae of Cx. tritaeniorhynchus, Ae. albopictus and An. subpictus with an LC(50) values of 14.01, 11.97 and 9.75 ppm and an LC(90) values of 23.44, 21.17 and 18.56 ppm, respectively. The results could be useful in search for newer, safer, and more effective natural larvicidal agents against Cx. tritaeniorhynchus, Ae. albopictus and An. subpictus. Copyright © 2013 Elsevier Inc. All rights reserved.

Optimization of DNA Barcode Method to Assess Altered Chemical Toxicity due to CYP-mediated Metabolism.

EPA Science Inventory

A drawback of current in vitro chemical testing is that many commonly used cell lines lack chemical metabolism. To address this challenge, we present a method for assessing the impact of cellular metabolism on chemical-based cellular toxicity. A cell line with low endogenous meta...

Optimization of DNA barcode method to assess altered chemical toxicity due to CYP-mediated metabolism

EPA Science Inventory

A drawback of current in vitro chemical testing is that many commonly used cell lines lack chemical metabolism. This hinders the use and relevance of cell culture in high throughput chemical toxicity screening. To address this challenge, we engineered HEK293T cells to overexpress...

Comparison of toxicity of class-based organic chemicals to algae and fish based on discrimination of excess toxicity from baseline level.

PubMed

Li, Jin J; Tai, Hong W; Yu, Yang; Wen, Yang; Wang, Xiao H; Zhao, Yuan H

2015-07-01

Toxicity data to fish and algae were used to investigate excess toxicity between species. Results show that chemicals exhibiting excess toxicity to fish also show excess toxicity to algae for most of the compounds. This indicates that they share the same mode of action between species. Similar relationships between logKOW and toxicities to fish and algae for baseline and less inert compounds suggest that they have similar critical body residues in the two species. Differences in excess toxicity for some compounds suggest that there is a difference of physiological structure and metabolism between fish and algae. Some reactive compounds (e.g. polyamines) exhibit greater toxic effects for algae than those for fish because of relatively low bio-uptake potential of these hydrophilic compounds in fish as compared with that in algae. Esters exhibiting greater toxicity in fish than that in algae indicate that metabolism can affect the discrimination of excess toxicity from baseline level. Algae growth inhibition is a very good surrogate for fish lethality. This is not only because overall toxicity sensitivity to algae is greater than that to fish, but also the excess toxicity calculated from algal toxicity can better reflect reactivity of compounds with target molecules than fish toxicity. Copyright © 2015 Elsevier B.V. All rights reserved.

Interaction of intraocular lenses with fibronectin and human lens epithelial cells: Effect of chemical composition and aging.

PubMed

Tortolano, Lionel; Serrano, Carole; Jubeli, Emile; Saunier, Johanna; Yagoubi, Najet

2015-12-01

The aim of this study is to investigate in vitro interactions between hydrophobic acrylate intraocular lenses (IOLs) and their biological environment. The influence of lens chemical composition and aging on fibronectin (FN) adsorption and on IOLs cytotoxicity on human lens epithelial cells was examined. Cytotoxicity of acrylate monomers used in IOLs manufacture was also investigated. Four different IOLs were included in the study: Acrysof(®), Tecnis(®), EnVista(®), and iSert(®). Implants were artificially aged in a xenon arc chamber to simulate 2 years of light exposure. Fibronectin adsorption on IOL surface was quantified using ELISA and correlated to surface roughness determined with AFM. Direct contact cytotoxicity was determined with the MTT assay and cell morphology was observed with light microscopy. Results showed that fibronectin adsorption did not differ significantly among IOLs, whatever their chemical composition. Moreover, aging conditions did not impact fibronectin adsorption. All IOLs were biocompatible even after applying 2-year aging conditions, with cell viability higher than 70%. Five acrylate monomers appeared to be toxic in the range of concentrations tested, but no monomer release from the IOLs could be detected during accelerated 2-year incubation with saline solution. This study did not reveal an influence of chemical composition and aging on protein adsorption and on biocompatibility. © 2015 Wiley Periodicals, Inc.

Chemical composition of Texas surface waters, 1949

USGS Publications Warehouse

Irelan, Burdge

1950-01-01

This report is the fifth the a series of publications by the Texas Board of Water Engineers giving chemical analyses of the surface waters in the State of Texas. The samples for which data are given were collected between October 1, 1948 and September 30, 1949. During the water year 25 daily sampling stations were maintained by the Geological Survey. Sampled were collected less frequently during the year at many other points. Quality of water records for previous years can be found in the following reports: "Chemical Composition of Texas Surface Waters, 1938-1945," by W. W. Hastings, and J. H. Rowley; "Chemical Composition of Texas Surface Waters, 1946," by W. W. Hastings and B. Irelan; "Chemical Composition of Texas Surface Waters, 1947," by B. Irelan and J. R. Avrett; "Chemical Composition of Texas Surface Waters, 1948," by B. Irelan, D. E. Weaver, and J. R. Avrett. These reports may be obtained from the Texas Board of Water Engineers and Geological Survey at Austin, Texas. Samples for chemical analysis were collected daily at or near points on streams where gaging stations are maintained for measurement of discharge. Most of the analyses were made of 10-day composites of daily samples collected for a year at each sampling point. Three composite samples were usually prepared each month by mixing together equal quantities of daily samples collected for the 1st to the 10th, from the 11th to the 20th, and during the remainder of the month. Monthly composites were made at a few stations where variation in daily conductance was small. For some streams that are subject to sudden large changes in chemical composition, composite samples were made for shorter periods on the basis of the concentration of dissolved solids as indicated by measurement of specific conductance of the daily samples. The mean discharge for the composite period is reported in second-feet. Specific conductance values are expressed as "micromhos, K x 10 at 25° C." Silica, calcium, magnesium, sodium

Impact of variations in the chemical composition of vitreous mineral fibers on biopersistence in rat lungs and consequences for regulation.

PubMed

Bellmann, Bernd; Schaeffer, Helmut A; Muhle, Hartwig

2010-08-01

The chronic toxicity of vitreous fibers is substantially dependent on their biopersistence. Removal of fibers deposited in the respiratory tract is dependent on a combination of physiological clearance processes (like mechanical translocation) and physico-chemical processes like dissolution and leaching. This publication presents data of about 60 different fibers investigated in the biopersistence test which was standardized in the European Union. This test is based on in vivo investigation of biopersistence after intratracheal instillation in rats of a respirable fiber fraction, and it is a basis for the regulatory classification of vitreous fibers. Regression analysis is carried out employing the data of glass fiber compositions and the corresponding results of biopersistence tests (half-times). The study leads to a model that enables prediction of half-times for stone wool fibers as well as for glass wool fibers on the basis of their chemical composition. The aim of this paper was to investigate the stringency of the existing limits for the range of the chemical composition of glass and stone wools in view of the currently available data base. For regulatory purposes, however, this model is currently not sufficient to replace biopersistence tests completely.

Reactive formulations for a neutralization of toxic industrial chemicals

DOEpatents

Tucker, Mark D [Albuqueruqe, NM; Betty, Rita G [Rio Rancho, NM

2006-10-24

Decontamination formulations for neutralization of toxic industrial chemicals, and methods of making and using same. The formulations are effective for neutralizing malathion, hydrogen cyanide, sodium cyanide, butyl isocyanate, carbon disulfide, phosgene gas, capsaicin in commercial pepper spray, chlorine gas, anhydrous ammonia gas; and may be effective at neutralizing hydrogen sulfide, sulfur dioxide, formaldehyde, ethylene oxide, methyl bromide, boron trichloride, fluorine, tetraethyl pyrophosphate, phosphorous trichloride, arsine, and tungsten hexafluoride.

Interrelationships among carcinogenicity, mutagenicity, acute toxicity, and chemical structure in a genotoxicity data base

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benigni, R.; Andreoli, C.; Giuliani, A.

1989-01-01

The interrelationships among carcinogenicity, mutagenicity, acute toxicity (LD50), and a number of molecular descriptors were studied by computerized data analysis methods on the data base generated by the International Program for the Evaluation of Short-Term Test for Carcinogens (IPESTTC). With the use of statistical regression methods, three main associations were evidenced: (1) the well-known correlation between carcinogenicity and mutagenicity; (2) a correlation between mutagenicity and toxicity (LD50 ip in mice); and (3) a correlation between toxicity and a recently introduced estimator of the free energy of binding of the molecules to biological receptors. As expected on the basis of themore » large variety of chemical classes represented in the IPESTTC data base, no simple relationship between mutagenicity or carcinogenicity and chemical descriptors was found. To overcome this problem, a new pattern recognition method (REPAD), developed by us for structure-activity studies of noncongeneric chemicals, has been used. This allowed us to highlight a significant difference between the whole patterns of relationships among chemicophysical variables in the two groups to active (mutagenicity and/or carcinogenic) and inactive chemicals. This approach generated a classification rule able to correctly assign about 80% of carcinogens or mutagens.« less

STRESS PATHWAY-BASED REPORTER ASSAYS TO ASSESS TOXICITY OF ENVIRONMENTAL CHEMICALS.

EPA Science Inventory

There is an increasing need for assays for the rapid and efficient assessment of toxicities of large numbers of environmental chemicals. To meet this need, we are developing cell-based reporter assays that measure the activation of key molecular stress pathways. We are using pro...

PREVENTION REFERENCE MANUAL: OVERVIEWS ON PREVENTING AND CONTROLLING ACCIDENTIAL RELEASES OF SELECTED TOXIC CHEMICALS

EPA Science Inventory

The manual can be used to orient personnel involved in inspecting and otherwise evaluating potential toxic chemical release hazards to the fundamentals of release hazard control for 13 of the specific chemicals chosen for evaluation under Section 305(b) of the Superfund Amendment...

Toxic Substances Registry System: Index of Material Safety Data Sheets. Revised

NASA Technical Reports Server (NTRS)

1997-01-01

The October 1997 revision of the Index of Material Safety Data Sheets (MSDS) for the Kennedy Space Center (KSC) Toxic Substances Registry System (TSRS) is presented. The MSDS lists toxic substances by manufacturer, trade name, stock number, and distributor. The index provides information on the hazards, use, and chemical composition of materials stored and used at KSC.

Chemical Composition of the Atmosphere

NASA Astrophysics Data System (ADS)

Schlager, Hans; Grewe, Volker; Roiger, Anke

Atmospheric trace gases have an important impact on Earth's radiative budget, the oxidative or cleansing ability of the atmosphere, the formation, growth and properties of aerosols, air quality, and human health. During recent years, the coupling between atmospheric chemistry and climate has received particular attention. Therefore, research is now focused on the composition and processes in the upper troposphere and lower stratosphere, a key region in this respect. In this chapter the chemical composition of the atmosphere is addressed and selected examples of significant advances in this field are presented.

Allium-test as a tool for toxicity testing of environmental radioactive-chemical mixtures

NASA Astrophysics Data System (ADS)

Oudalova, A. A.; Geras'kin, S. A.; Dikareva, N. S.; Pyatkova, S. V.

2017-01-01

Bioassay-based approaches have been propagated to assess toxicity of unknown mixtures of environmental contaminants, but it was rarely applied in cases of chemicals with radionuclides combinations. Two Allium-test studies were performed to assess environmental impact from potential sources of combined radioactive-chemical pollution. Study sites were located at nuclear waste storage facilities in European and in Far-Eastern parts of Russia. As environmental media under impact, waters from monitor wells and nearby water bodies were tested. Concentrations of some chemicals and radionuclides in the samples collected enhanced the permitted limits. Cytogenetic and cytotoxic effects were used as biological endpoints, namely, frequency and spectrum of chromosome aberrations and mitotic abnormalities in anatelophase cells as well as mitotic activity in Allium root tips. Sample points were revealed where waters have an enhanced mutagenic potential. The findings obtained could be used to optimize monitoring system and advance decision making on management and rehabilitation of industrial sites. The Allium-test could be recommended and applied as an effective tool for toxicity testing in case of combined contamination of environmental compartments with radionuclides and chemical compounds.

Developmental toxicity in flounder embryos exposed to crude oils derived from different geographical regions.

PubMed

Jung, Jee-Hyun; Lee, Eun-Hee; Choi, Kwang-Min; Yim, Un Hyuk; Ha, Sung Yong; An, Joon Geon; Kim, Moonkoo

2017-06-01

Crude oils from distinct geographical regions have distinct chemical compositions, and, as a result, their toxicity may be different. However, developmental toxicity of crude oils derived from different geographical regions has not been extensively characterized. In this study, flounder embryos were separately exposed to effluents contaminated by three crude oils including: Basrah Light (BLO), Pyrenees (PCO), and Sakhalin Vityaz (SVO), in addition to a processed fuel oil (MFO-380), to measure developmental toxicity and for gene expressions. Each oil possessed a distinct chemical composition. Edema defect was highest in embryos exposed to PCO and MFO-380 that both have a greater fraction of three-ring PAHs (33% and 22%, respectively) compared to BLO and SVO. Observed caudal fin defects were higher in embryos exposed to SVO and MFO-380, which are both dominated by naphthalenes (81% and 52%, respectively). CYP1A gene expressions were also highest in embryos exposed to SVO and MFO-380. Higher incidence of cardiotoxicity and lower nkx 2.5 expression were detected in embryos exposed to PCO. Unique gene expression profiles were observed in embryos exposed to crude oils with distinct compositions. This study demonstrates that crude oils of different geographical origins with different compositional characteristics induce developmental toxicity to different degrees. Copyright © 2017 Elsevier Inc. All rights reserved.

Environmental and Chemical Aging of Fatty-Acid-Based Vinyl Ester Composites

DTIC Science & Technology

2011-04-01

Environmental and Chemical Aging of Fatty- Acid -Based Vinyl Ester Composites by Steven E. Boyd and John J. La Scala ARL-TR-5523 April...2011 Environmental and Chemical Aging of Fatty- Acid -Based Vinyl Ester Composites Steven E. Boyd and John J. La Scala Weapons and Materials...COVERED (From - To) October 2009–September 2010 4. TITLE AND SUBTITLE Environmental and Chemical Aging of Fatty- Acid -Based Vinyl Ester Composites

Protecting children from toxic chemicals: putting it on Australia's public health agenda.

PubMed

Lantz, Sarah

2013-11-01

The high volume and widespread use of industrial chemicals, the backlog of internationally untested chemicals, the uptake of synthetic chemicals found in babies in utero, cord blood, and in breast milk, and the lack of a unified and comprehensive regulatory framework all necessitate developing policies that protect the most vulnerable in our society - our children. Australia's failure to do so raises profound intergenerational ethical issues. This article tells a story of international policy, and where Australia is falling down. It demonstrates that we can learn from countries already taking critical steps to reduce the toxic chemical exposure, and that the development of a comprehensive, child-centered chemical regulation framework is central to turning around Australia's failure.

Chemical composition of fat and oil products

USDA-ARS?s Scientific Manuscript database

Fats and oils are an important dietary component, and contribute to the nutritional and sensory quality of foods. This chapter focuses on the chemical composition of fats and oils, and how these compositions affect the functional properties of fats and oils in foods. The focus will remain on the mos...

The Chemical Composition of Essential Oils from Cinnamomum camphora and Their Insecticidal Activity against the Stored Product Pests.

PubMed

Guo, Shanshan; Geng, Zhufeng; Zhang, Wenjuan; Liang, Junyu; Wang, Chengfang; Deng, Zhiwei; Du, Shushan

2016-11-04

To investigate the chemical composition and insecticidal activity of the essential oils of certain Chinese medicinal herbs and spices, the essential oils were extracted from the stem barks, leaves, and fruits of Cinnamomum camphora (L.) Presl, which were found to possess strong fumigant toxicity against Tribolium castaneum and Lasioderma serricorne adults. The essential oils of the plants were extracted by the method of steam distillation using a Clavenger apparatus. Their composition was determined by gas chromatography/mass spectrometric (GC-MS) analyses (HP-5MS column), and their insecticidal activity was measured by seal-spaced fumigation. D-camphor (51.3%), 1,8-cineole (4.3%), and α-terpineol (3.8%), while D-camphor (28.1%), linalool (22.9%), and 1,8-cineole (5.3%) were the main constituents of its fruits. The essential oils of the C. camphora all showed fumigant and contact toxicity. Other compounds exhibited various levels of bioactivities. The results indicate that the essential oils of C. camphora and its individual compounds can be considered a natural resource for the two stored-product insect management.

Vector diagram of the chemical compositions of tektites and earth lavas

NASA Technical Reports Server (NTRS)

Kvasha, L. G.; Gorshkov, G. S.

1978-01-01

The chemical compositions of tektites and various volcanic glasses, similar in composition to tektites are compared by a petrochemical method. The advantage of the method is that a large number of chemical analyses of igneous rocks can be graphically compared with the help of vectors, plotted in relation to six parameters. These parameters, calculated from ratios of the main oxides given by silicate analysis, reflect the chief characteristics of igneous rock. Material for the study was suppled by data from chemical analysis characterizing tektites of all known locations and data from chemical analyses of obsidians similar in chemical composition to tektites of various petrographical provinces.

Diet composition modifies the toxicity of repeated soman exposure in rats.

PubMed

Langston, Jeffrey L; Myers, Todd M

2011-12-01

It was previously demonstrated that diet potently modulates the toxic effects of an acute lethal dose of the nerve agent soman. The current investigation was undertaken to examine the influence of diet on the cumulative toxicity of repeated soman administration. Rats were fed one of four distinct diets (standard, choline-enriched, glucose-enriched, or ketogenic) for four weeks prior to and throughout a repeated soman dosing and recovery regimen. Each diet group included animals exposed to an equivalent volume of saline that served as negative controls. In exposure Week 1, animals received three consecutive daily doses of 0.4 LD(50) soman. In exposure Week 2, animals received four consecutive daily doses of 0.5 LD(50) soman. In exposure Week 3, animals received five consecutive daily doses of 0.5 LD(50) soman. Week 4 constituted a post-exposure recovery evaluation. Throughout the experiment, behavioral function was assessed by a discriminated avoidance test that required intact sensory and motor function. Survival and body weight changes were recorded daily. Differences in toxicity as a function of diet composition became apparent during the first week. Specifically, rats fed the glucose-enriched diet showed pronounced intoxication during Week 1, resulting in imperfect survival, weight loss, and deteriorated avoidance performance relative to all other groups. All rats fed the glucose-enriched diet died by the end of exposure Week 2. In contrast, only 10% of animals fed the standard diet died by the end of Week 2. Also in Week 2, weight loss and disrupted avoidance performance were apparent for all groups except for those fed the ketogenic diet. This differential effect of diet composition became even more striking in Week 3 when survival in the standard and choline diet groups approximated 50%, whereas survival equaled 90% in the ketogenic diet group. Avoidance performance and weight loss measures corroborated the differential toxicity observed across diet groups

Toxic effects of the interaction of titanium dioxide nanoparticles with chemicals or physical factors

PubMed Central

Liu, Kui; Lin, Xialu; Zhao, Jinshun

2013-01-01

Due to their chemical stability and nonallergic, nonirritant, and ultraviolet protective properties, titanium dioxide (TiO2) nanoparticles (NPs) have been widely used in industries such as electronics, optics, and material sciences, as well as architecture, medicine, and pharmacology. However, increasing concerns have been raised in regards to its ecotoxicity and toxicity on the aquatic environment as well as to humans. Although insights have been gained into the effects of TiO2 NPs on susceptible biological systems, there is still much ground to be covered, particularly in respect of our knowledge of the effects of the interaction of TiO2 NPs with other chemicals or physical factors. Studies suggest that interactions of TiO2 NPs with other chemicals or physical factors may result in an increase in toxicity or adverse effects. This review highlights recent progress in the study of the interactive effects of TiO2 NPs with other chemicals or physical factors. PMID:23901269

Bulk chemical compositions of Antarctic meteorites in the NIPR collection

NASA Astrophysics Data System (ADS)

Kimura, M.; Imae, N.; Yamaguchi, A.; Haramura, H.; Kojima, H.

2018-03-01

Bulk chemical compositions of meteorites were traditionally analyzed by wet chemical analysis, and NIPR has data for 1162 meteorites as of September 2017. We discuss the classification of meteorites on the basis of these data. Chondrite data are distributed in an anomalously wide range of compositions on the Urey-Craig diagram. One of the reasons for such wide distribution is terrestrial weathering producing Fe2O3-bearing phases from Fe-Ni metal and sulfides. Another important factor affecting the bulk compositional data is brecciation. Our observations indicate that many brecciated chondrites contain anomalously abundant opaque minerals, or are depleted in them, resulting in unusual compositions. In case of enstatite and some carbonaceous chondrites, the bulk compositions are distributed in wider ranges than reported before. The bulk compositions of HED meteorites are consistent with their mineralogy and classification. Our study suggests that wet chemical data are still significant for the meteorite classification. However, petrographic observation is indispensable for evaluating the bulk chemistry and classification of meteorites.

Pulsed plasma chemical synthesis of SixCyOz composite nanopowder

NASA Astrophysics Data System (ADS)

Kholodnaya, G.; Sazonov, R.; Ponomarev, D.; Remnev, G.

2017-05-01

SixCyOz composite nanopowder with an average size of particles about 10-50 nm was produced using the pulsed plasma chemical method. The experiments on the synthesis of nanosized composite were carried out using a TEA-500 pulsed electron accelerator. To produce a composite, SiCl4, O2, and CH4 were used. The major part of experiments was conducted using a plasma chemical reactor (quartz, 140 mm diameter, 6 l volume). The initial reagents were injected into the reactor, then a pulsed electron beam was injected which initiated the chemical reactions whose products were the SixCyOz composite nanopowder. To define the morphology of the particles, the JEOL-II-100 transmission electron microscope (TEM) with an accelerating voltage of 100 kV was used. The substances in the composition of the composite nanopowder were identified using the infrared absorption optical spectrum. To conduct this analysis, the Nicolet 5700 FT-IR spectrometer was used.

Chemical characterization, pharmacological effects, and toxicity of an ethanol extract of Celtis pallida Torr. (Cannabaceae) aerial parts.

PubMed

Rojas-Bedolla, Edgar Isaac; Gutiérrez-Pérez, Jorge Luis; Arenas-López, Mario Iván; González-Chávez, Marco Martin; Zapata-Morales, Juan Ramón; Mendoza-Macías, Claudia Leticia; Carranza-Álvarez, Candy; Maldonado-Miranda, Juan José; Deveze-Álvarez, Martha Alicia; Alonso-Castro, Angel Josabad

2018-06-12

Celtis pallida Torr (Cannabaceae) is employed as a folk medicine for the treatment of inflammation, pain, skin infections, and diarrhea, among other diseases. The purpose of this work was to assess the chemical composition, the in vitro and in vivo toxicity, the antimicrobial, anti-inflammatory, antidiarrheal, antinociceptive, locomotor, and sedative effects of an ethanolic extract obtained from Celtis pallida aerial parts (CPE). The composition of CPE was carried out by GC-MS. The in vitro and in vivo toxic activity of CPE was estimated with the comet assay (10-1000 µg/ml) for 5 h in peripheral blood mononuclear cells, and the acute toxicity test (500-5000 mg/kg p.o.), for 14 days, respectively. The antimicrobial effect of CPE was evaluated using the minimum inhibitory concentration (MIC) assay, whereas the antidiarrheal activity (10-200 mg/kg p.o.) was calculated using the castor oil test. The antinociceptive effects of CPE (50-200 mg/kg p.o.) were estimated with the acetic acid and formalin tests, as well as the hot plate test. The sedative and locomotor activities of CPE (50-200 mg/kg p.o.) were assessed with the pentobarbital-induced sleeping time test and the rotarod test, respectively. The main compound found in CPE was the triterpene ursolic acid (22% of the extract). CPE at concentrations of 100 µg/ml or higher induced genotoxicity in vitro and showed low in vivo toxicity (LD 50 > 5000 mg/kg p.o.). Additionally, CPE lacked (MIC > 400 µg/ml) antimicrobial activity but exerts antinociceptive (ED 50 = 12.5 ± 1.5 mg/kg) and antidiarrheal effects (ED 50 = 2.8 mg/kg), without inducing sedative effects or altering the locomotor activity. The antinociceptive activity of CPE suggests the participation of adrenoceptors, as well as the nitric oxide/cyclic guanosine monophosphate (cGMP) pathway. C. pallida exerts its antinociceptive effects probably mediated by the nitric oxide/cyclic guanosine monophosphate (cGMP) pathway. Copyright �

Fate of chemical warfare agents and toxic industrial chemicals in landfills.

PubMed

Bartelt-Hunt, Shannon L; Barlaz, Morton A; Knappe, Detlef R U; Kjeldsen, Peter

2006-07-01

One component of preparedness for a chemical attack is planning for the disposal of contaminated debris. To assess the feasibility of contaminated debris disposal in municipal solid waste (MSW) landfills, the fate of selected chemical warfare agents (CWAs) and toxic industrial chemicals (TICs) in MSW landfills was predicted with a mathematical model. Five blister agents [sulfur mustard (HD), nitrogen mustard (HN-2), lewisite (L), ethyldichloroarsine (ED), and phosgene oxime (CX)], eight nerve agents [tabun (GA), sarin (GB), soman (GD), GE, GF, VX, VG, and VM], one riot-control agent [CS], and two TICs [furan and carbon disulfide] were studied. The effects of both infiltration (climate) and contaminant biodegradability on fate predictions were assessed. Model results showed that hydrolysis and gas-phase advection were the principal fate pathways for CWAs and TICs, respectively. Apart from CX and the TICs, none of the investigated compounds was predicted to persist in a landfill for more than 5 years. Climate had little impact on CWA/TIC fate, and biodegradability was only important for compounds with long hydrolysis half-lives. Monte Carlo simulations were performed to assess the influence of uncertainty in model input parameters on CWA/TIC fate predictions. Correlation analyses showed that uncertainty in hydrolysis rate constants was the primary contributor to variance of CWA fate predictions, while uncertainty in the Henry's Law constant and landfill gas-production rate accounted for most of the variance of TIC fate predictions. CWA hydrolysates were more persistent than the parent CWAs, but limited information is available on abiotic or biotic transformation rates for these chemicals.

Biofuel Mixture Composition and Parameters of Exhaust Gases Toxicity

NASA Astrophysics Data System (ADS)

Markov, V. A.; Kamaltdinov, V. G.; Loboda, S. S.

2018-03-01

Advantages of using fuels of vegetable origin as motor fuels are shown. Possible ways of using cameline oil as a fuel for a diesel engine are considered. Experimental research of diesel engine D-245.12S functioning on mixtures of diesel fuel and cameline oil of various percentage is given. Parameters of exhaust gases toxicity of the diesel engine by using these mixtures of various compositions are analyzed.

Reduced toxicity polyester resins and microvascular pre-preg tapes for advanced composites manufacturing

NASA Astrophysics Data System (ADS)

Poillucci, Richard

Advanced composites manufacturing broadly encapsulates topics ranging from matrix chemistries to automated machines that lay-up fiber-reinforced materials. Environmental regulations are stimulating research to reduce matrix resin formulation toxicity. At present, composites fabricated with polyester resins expose workers to the risk of contact with and inhalation of styrene monomer, which is a potential carcinogen, neurotoxin, and respiratory irritant. The first primary goal of this thesis is to reduce the toxicity associated with polyester resins by: (1) identification of potential monomers to replace styrene, (2) determination of monomer solubility within the polyester, and (3) investigation of approaches to rapidly screen a large resin composition parameter space. Monomers are identified based on their ability to react with polyester and their toxicity as determined by the Globally Harmonized System (GHS) and a green screen method. Solubilities were determined by the Hoftyzer -- Van Krevelen method, Hansen solubility parameter database, and experimental mixing of monomers. A combinatorial microfluidic mixing device is designed and tested to obtain distinct resin compositions from two input chemistries. The push for safer materials is complemented by a thrust for multifunctional composites. The second primary goal of this thesis is to design and implement the manufacture of sacrificial fiber materials suitable for use in automated fiber placement of microvascaular multifunctional composites. Two key advancements are required to achieve this goal: (1) development of a roll-to-roll method to place sacrificial fibers onto carbon fiber pre-preg tape; and (2) demonstration of feasible manufacture of microvascular carbon fiber plates with automated fiber placement. An automated method for placing sacrificial fibers onto carbon fiber tapes is designed and a prototype implemented. Carbon fiber tows with manual placement of sacrificial fibers is implemented within an

Impact of Environmentally Based Chemical Hardness on Uranium Speciation and Toxicity in Six Aquatic Species

PubMed Central

Goulet, Richard R; Thompson, Patsy A; Serben, Kerrie C; Eickhoff, Curtis V

2015-01-01

Treated effluent discharge from uranium (U) mines and mills elevates the concentrations of U, calcium (Ca), magnesium (Mg), and sulfate (SO42–) above natural levels in receiving waters. Many investigations on the effect of hardness on U toxicity have been experiments on the combined effects of changes in hardness, pH, and alkalinity, which do not represent water chemistry downstream of U mines and mills. Therefore, more toxicity studies with water chemistry encountered downstream of U mines and mills are necessary to support predictive assessments of impacts of U discharge to the environment. Acute and chronic U toxicity laboratory bioassays were realized with 6 freshwater species in waters of low alkalinity, circumneutral pH, and a range of chemical hardness as found in field samples collected downstream of U mines and mills. In laboratory-tested waters, speciation calculations suggested that free uranyl ion concentrations remained constant despite increasing chemical hardness. When hardness increased while pH remained circumneutral and alkalinity low, U toxicity decreased only to Hyalella azteca and Pseudokirchneriella subcapitata. Also, Ca and Mg did not compete with U for the same uptake sites. The present study confirms that the majority of studies concluding that hardness affected U toxicity were in fact studies in which alkalinity and pH were the stronger influence. The results thus confirm that studies predicting impacts of U downstream of mines and mills should not consider chemical hardness. PMID:25475484

Removal efficiency and toxicity reduction of 4-chlorophenol with physical, chemical and biochemical methods.

PubMed

Gómez, M; Murcia, M D; Dams, R; Christofi, N; Gómez, E; Gómez, J L

2012-01-01

Chlorophenols are well-known priority pollutants and many different treatments have been assessed to facilitate their removal from industrial wastewater. However, an absolute and optimum solution still has to be practically implemented in an industrial setting. In this work, a series ofphysical, chemical and biochemical treatments have been systematically tested for the removal of 4-chlorophenol, and their results have been compared in order to determine the most effective treatment based on removal efficiency and residual by-product formation. Chemical treatments based on advanced oxidation processes (AOP) produced the best results on rate and extent of pollutant removal. The non-chemical technologies showed advantages in terms of complete (in the case of adsorption) or easy (enzymatic treatments) removal of toxic treatment by-products. The AOP methods led to the production of different photoproducts depending on the chosen treatment. Toxic products remained in most cases following treatment, though the toxicity level is significantly reduced with combination treatments. Among the treatments, a photochemical method combining UV, produced with a KrCl excilamp, and hydrogen peroxide achieved total removal of chlorophenol and all by-products and is considered the best treatment for chlorophenol removal.

Export of toxic chemicals - a review of the case of uncontrolled electronic-waste recycling.

PubMed

Wong, M H; Wu, S C; Deng, W J; Yu, X Z; Luo, Q; Leung, A O W; Wong, C S C; Luksemburg, W J; Wong, A S

2007-09-01

This paper reviews the concentrations of persistent organic pollutants such as flame retardants (PBDEs), dioxins/furans (PCDD/Fs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and heavy metals/metalloid concentrations of different environmental media at Guiyu, a traditional rice-growing village located in southeastern Guangdong Province (PR China), which has turned into an intensive electronic-waste (e-waste) recycling site. Incomplete combustion of e-waste in open air and dumping of processed materials are the major sources of various toxic chemicals. By comparing with existing data available in other areas and also guidelines adopted in different countries, it is obvious that the environment is highly contaminated by these toxic chemicals derived from the recycling processes. For example, the monthly concentration of the sum of 22 PBDE congeners contained in PM(2.5) (16.8ngm(-3)) of air samples at Guiyu was 100 times higher than published data. In order to safeguard the environment and human health, detailed investigations are urgently needed, especially on tracking the exposure pathways of different toxic chemicals which may affect the workers and local residents especially mothers, infants and children.

LINKING EFFECTS OF PERSISTENT BIOACCUMULATIVE TOXICANTS TO CHEMICAL EXPOSURES IN AQUATIC ECOSYSTEMS

EPA Science Inventory

The critical step in characterization of ecological risks associated with exposures of fish and wildlife to persistent bioaccumulative toxicants (PBTs) is linking chemical residue based toxicological data to concentrations of PBTs in sediments, water, and biota. This is necessary...

Relative sensitivity of Arctic species to physically and chemically dispersed oil determined from three hydrocarbon measures of aquatic toxicity.

PubMed

Bejarano, Adriana C; Gardiner, William W; Barron, Mace G; Word, Jack Q

2017-09-15

The risks to Arctic species from oil releases is a global concern, but their sensitivity to chemically dispersed oil has not been assessed using a curated and standardized dataset from spiked declining tests. Species sensitivity to dispersed oil was determined by their position within species sensitivity distributions (SSDs) using three measures of hydrocarbon toxicity: total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbon (PAHs), and naphthalenes. Comparisons of SSDs with Arctic/sub-Arctic versus non-Arctic species, and across SSDs of compositionally similar oils, showed that Arctic and non-Arctic species have comparable sensitivities even with the variability introduced by combining data across studies and oils. Regardless of hydrocarbon measure, hazard concentrations across SSDs were protective of sensitive Arctic species. While the sensitivities of Arctic species to oil exposures resemble those of commonly tested species, PAH-based toxicity data are needed for a greater species diversity including sensitive Arctic species. Copyright © 2017 Elsevier Ltd. All rights reserved.

40 CFR 372.85 - Toxic chemical release reporting form and instructions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 27 2010-07-01 2010-07-01 false Toxic chemical release reporting form... my knowledge and belief, the submitted information is true and complete and that amounts and values... year ending December 31, 2005, for which reporting forms are due July 1, 2006. Beginning with the...

40 CFR 372.85 - Toxic chemical release reporting form and instructions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 28 2011-07-01 2011-07-01 false Toxic chemical release reporting form... my knowledge and belief, the submitted information is true and complete and that amounts and values... year ending December 31, 2005, for which reporting forms are due July 1, 2006. Beginning with the...

40 CFR 372.85 - Toxic chemical release reporting form and instructions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 28 2014-07-01 2014-07-01 false Toxic chemical release reporting form... have reviewed the attached documents and, to the best of my knowledge and belief, the submitted... establishments in the facility until the reporting year ending December 31, 2005, for which reporting forms are...

40 CFR 372.85 - Toxic chemical release reporting form and instructions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 29 2013-07-01 2013-07-01 false Toxic chemical release reporting form... my knowledge and belief, the submitted information is true and complete and that amounts and values... year ending December 31, 2005, for which reporting forms are due July 1, 2006. Beginning with the...

40 CFR 372.85 - Toxic chemical release reporting form and instructions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 29 2012-07-01 2012-07-01 false Toxic chemical release reporting form... my knowledge and belief, the submitted information is true and complete and that amounts and values... year ending December 31, 2005, for which reporting forms are due July 1, 2006. Beginning with the...

Antibacterial properties and toxicity from metallic nanomaterials

PubMed Central

Vimbela, Gina V; Ngo, Sang M; Fraze, Carolyn; Yang, Lei; Stout, David A

2017-01-01

The era of antibiotic resistance is a cause of increasing concern as bacteria continue to develop adaptive countermeasures against current antibiotics at an alarming rate. In recent years, studies have reported nanoparticles as a promising alternative to antibacterial reagents because of their exhibited antibacterial activity in several biomedical applications, including drug and gene delivery, tissue engineering, and imaging. Moreover, nanomaterial research has led to reports of a possible relationship between the morphological characteristics of a nanomaterial and the magnitude of its delivered toxicity. However, conventional synthesis of nanoparticles requires harsh chemicals and costly energy consumption. Additionally, the exact relationship between toxicity and morphology of nanomaterials has not been well established. Here, we review the recent advancements in synthesis techniques for silver, gold, copper, titanium, zinc oxide, and magnesium oxide nanomaterials and composites, with a focus on the toxicity exhibited by nanomaterials of multidimensions. This article highlights the benefits of selecting each material or metal-based composite for certain applications while also addressing possible setbacks and the toxic effects of the nanomaterials on the environment. PMID:28579779

Emergency planning and preparedness for the deliberate release of toxic industrial chemicals.

PubMed

Russell, David; Simpson, John

2010-03-01

Society in developed and developing countries is hugely dependent upon chemicals for health, wealth, and economic prosperity, with the chemical industry contributing significantly to the global economy. Many chemicals are synthesized, stored, and transported in vast quantities and classified as high production volume chemicals; some are recognized as being toxic industrial chemicals (TICs). Chemical accidents involving chemical installations and transportation are well recognized. Such chemical accidents occur with relative frequency and may result in large numbers of casualties with acute and chronic health effects as well as fatalities. The large-scale production of TICs, the potential for widespread exposure and significant public health impact, together with their relative ease of acquisition, makes deliberate release an area of potential concern. The large numbers of chemicals, together with the large number of potential release scenarios means that the number of possible forms of chemical incident are almost infinite. Therefore, prior to undertaking emergency planning and preparedness, it is necessary to prioritize risk and subsequently mitigate. This is a multi-faceted process, including implementation of industrial protection layers, substitution of hazardous chemicals, and relocation away from communities. Residual risk provides the basis for subsequent planning. Risk-prioritized emergency planning is a tool for identifying gaps, enhancing communication and collaboration, and for policy development. It also serves to enhance preparedness, a necessary prelude to preventing or mitigating the public health risk to deliberate release. Planning is an iterative and on-going process that requires multi-disciplinary agency input, culminating in the formation of a chemical incident plan complimentary to major incident planning. Preparedness is closely related and reflects a state of readiness. It is comprised of several components, including training and exercising

SEDIMENT CHEMICAL CONTAMINATION AND TOXICITY ASSOCIATED WITH A COASTAL GOLF COURSE COMPLEX.

EPA Science Inventory

The increasing density of golf courses represents a potential source of sediment contamination to nearby coastal areas, the chemical and biological magnitude of which is almost unknown. The objective of this study was to determine the concentrations of contaminants and toxicities...

Prioritizing ToxCast Chemicals Across Multiple Sectors of Toxicity Using ToxPi

EPA Science Inventory

The Toxicological Prioritization Index (ToxPi™) framework was developed as a decision-support tool to aid in the rational prioritization of chemicals for integrated toxicity testing. ToxPi consolidates information from multiple domains—including ToxCast™ in vitro bioactivity prof...

Assessing deep and shallow learning methods for quantitative prediction of acute chemical toxicity.

PubMed

Liu, Ruifeng; Madore, Michael; Glover, Kyle P; Feasel, Michael G; Wallqvist, Anders

2018-05-02

Animal-based methods for assessing chemical toxicity are struggling to meet testing demands. In silico approaches, including machine-learning methods, are promising alternatives. Recently, deep neural networks (DNNs) were evaluated and reported to outperform other machine-learning methods for quantitative structure-activity relationship modeling of molecular properties. However, most of the reported performance evaluations relied on global performance metrics, such as the root mean squared error (RMSE) between the predicted and experimental values of all samples, without considering the impact of sample distribution across the activity spectrum. Here, we carried out an in-depth analysis of DNN performance for quantitative prediction of acute chemical toxicity using several datasets. We found that the overall performance of DNN models on datasets of up to 30,000 compounds was similar to that of random forest (RF) models, as measured by the RMSE and correlation coefficients between the predicted and experimental results. However, our detailed analyses demonstrated that global performance metrics are inappropriate for datasets with a highly uneven sample distribution, because they show a strong bias for the most populous compounds along the toxicity spectrum. For highly toxic compounds, DNN and RF models trained on all samples performed much worse than the global performance metrics indicated. Surprisingly, our variable nearest neighbor method, which utilizes only structurally similar compounds to make predictions, performed reasonably well, suggesting that information of close near neighbors in the training sets is a key determinant of acute toxicity predictions.

Chemical Compounds Toxic to Invertebrates Isolated from Marine Cyanobacteria of Potential Relevance to the Agricultural Industry

PubMed Central

Essack, Magbubah; Alzubaidy, Hanin S.; Bajic, Vladimir B.; Archer, John A. C.

2014-01-01

In spite of advances in invertebrate pest management, the agricultural industry is suffering from impeded pest control exacerbated by global climate changes that have altered rain patterns to favour opportunistic breeding. Thus, novel naturally derived chemical compounds toxic to both terrestrial and aquatic invertebrates are of interest, as potential pesticides. In this regard, marine cyanobacterium-derived metabolites that are toxic to both terrestrial and aquatic invertebrates continue to be a promising, but neglected, source of potential pesticides. A PubMed query combined with hand-curation of the information from retrieved articles allowed for the identification of 36 cyanobacteria-derived chemical compounds experimentally confirmed as being toxic to invertebrates. These compounds are discussed in this review. PMID:25356733

Chemical compounds toxic to invertebrates isolated from marine cyanobacteria of potential relevance to the agricultural industry.

PubMed

Essack, Magbubah; Alzubaidy, Hanin S; Bajic, Vladimir B; Archer, John A C

2014-10-29

In spite of advances in invertebrate pest management, the agricultural industry is suffering from impeded pest control exacerbated by global climate changes that have altered rain patterns to favour opportunistic breeding. Thus, novel naturally derived chemical compounds toxic to both terrestrial and aquatic invertebrates are of interest, as potential pesticides. In this regard, marine cyanobacterium-derived metabolites that are toxic to both terrestrial and aquatic invertebrates continue to be a promising, but neglected, source of potential pesticides. A PubMed query combined with hand-curation of the information from retrieved articles allowed for the identification of 36 cyanobacteria-derived chemical compounds experimentally confirmed as being toxic to invertebrates. These compounds are discussed in this review.

The Chemical Composition of Honey

ERIC Educational Resources Information Center

Ball, David W.

2007-01-01

Honey is a supersaturated sugar solution, created by bees, and used by human beings as a sweetener. However, honey is more than just a supersaturated sugar solution; it also contains acids, minerals, vitamins, and amino acids in varying quantities. In this article, we will briefly explore the chemical composition of honey. (Contains 2 figures and…

The Chemical Composition of Maple Syrup

ERIC Educational Resources Information Center

Ball, David W.

2007-01-01

Maple syrup is one of several high-sugar liquids that humans consume. However, maple syrup is more than just a concentrated sugar solution. Here, we review the chemical composition of maple syrup. (Contains 4 tables and 1 figure.)

A systematic study of mitochondrial toxicity of environmental chemicals using quantitative high throughput screening

PubMed Central

Attene-Ramos, Matias S.; Huang, Ruili; Sakamuru, Srilatha; Witt, Kristine L.; Beeson, Gyda C.; Shou, Louie; Schnellmann, Rick G.; Beeson, Craig C.; Tice, Raymond R.; Austin, Christopher P.; Xia, Menghang

2014-01-01

A goal of the Tox21 program is to transit toxicity testing from traditional in vivo models to in vitro assays that assess how chemicals affect cellular responses and toxicity pathways. A critical contribution of the NIH Chemical Genomics center (NCGC) to the Tox21 program is the implementation of a quantitative high throughput screening (qHTS) approach, using cell- and biochemical-based assays to generate toxicological profiles for thousands of environmental compounds. Here, we evaluated the effect of chemical compounds on mitochondrial membrane potential in HepG2 cells by screening a library of 1,408 compounds provided by the National Toxicology Program (NTP) in a qHTS platform. Compounds were screened over 14 concentrations, and results showed that 91 and 88 compounds disrupted mitochondrial membrane potential after treatment for one or five h, respectively. Seventy-six compounds active at both time points were clustered by structural similarity, producing 11 clusters and 23 singletons. Thirty-eight compounds covering most of the active chemical space were more extensively evaluated. Thirty-six of the 38 compounds were confirmed to disrupt mitochondrial membrane potential using a fluorescence plate reader and 35 were confirmed using a high content imaging approach. Among the 38 compounds, 4 and 6 induced LDH release, a measure of cytotoxicity, at 1 or 5 h, respectively. Compounds were further assessed for mechanism of action (MOA) by measuring changes in oxygen consumption rate, which enabled identification of 20 compounds as uncouplers. This comprehensive approach allows for evaluation of thousands of environmental chemicals for mitochondrial toxicity and identification of possible MOAs. PMID:23895456

Developing predictive models for toxicity of organic chemicals to green algae based on mode of action.

PubMed

Bakire, Serge; Yang, Xinya; Ma, Guangcai; Wei, Xiaoxuan; Yu, Haiying; Chen, Jianrong; Lin, Hongjun

2018-01-01

Organic chemicals in the aquatic ecosystem may inhibit algae growth and subsequently lead to the decline of primary productivity. Growth inhibition tests are required for ecotoxicological assessments for regulatory purposes. In silico study is playing an important role in replacing or reducing animal tests and decreasing experimental expense due to its efficiency. In this work, a series of theoretical models was developed for predicting algal growth inhibition (log EC 50 ) after 72 h exposure to diverse chemicals. In total 348 organic compounds were classified into five modes of toxic action using the Verhaar Scheme. Each model was established by using molecular descriptors that characterize electronic and structural properties. The external validation and leave-one-out cross validation proved the statistical robustness of the derived models. Thus they can be used to predict log EC 50 values of chemicals that lack authorized algal growth inhibition values (72 h). This work systematically studied algal growth inhibition according to toxic modes and the developed model suite covers all five toxic modes. The outcome of this research will promote toxic mechanism analysis and be made applicable to structural diversity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chemical characterization and in vitro toxicity of diesel exhaust particulate matter generated under varying conditions

PubMed Central

Cox, David P.; Drury, Bertram E.; Gould, Timothy R.; Kavanagh, Terrance J.; Paulsen, Michael H.; Sheppard, Lianne; Simpson, Christopher D.; Stewart, James A.; Larson, Timothy V.; Kaufman, Joel D.

2014-01-01

Epidemiologic studies have linked diesel exhaust (DE) to cardiovascular and respiratory morbidity and mortality, as well as lung cancer. DE composition is known to vary with many factors, although it is unclear how this influences toxicity. We generated eight DE atmospheres by applying a 2×2×2 factorial design and altering three parameters in a controlled exposure facility: (1) engine load (27 vs 82 %), (2) particle aging (residence time ~5 s vs ~5 min prior to particle collection), and (3) oxidation (with or without ozonation during dilution). Selected exposure concentrations of both diesel exhaust particles (DEPs) and DE gases, DEP oxidative reactivity via DTT activity, and in vitro DEP toxicity in murine endothelial cells were measured for each DE atmosphere. Cell toxicity was assessed via measurement of cell proliferation (colony formation assay), cell viability (MTT assay), and wound healing (scratch assay). Differences in DE composition were observed as a function of engine load. The mean 1-nitropyrene concentration was 15 times higher and oxidative reactivity was two times higher for low engine load versus high load. There were no substantial differences in measured toxicity among the three DE exposure parameters. These results indicate that alteration of applied engine load shifts the composition and can modify the biological reactivity of DE. While engine conditions did not affect the selected in vitro toxicity measures, the change in oxidative reactivity suggests that toxicological studies with DE need to take into account engine conditions in characterizing biological effects. PMID:26539254

Effect of diet composition on vanadium toxicity for the chick

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berg, L.R.

1966-01-01

Studies to determine the effect of diet composition on the toxicity of 20 ppm added vanadium for the young chick have shown: growth depression of 25-30% with a corn-soybean meal ration but only 3-7% with a corn-herring fish meal diet. Growth depression of 35-40% with a semi-purified sucrose-soybean meal diet and approximately 50% with a diet of sucrose and herring fish meal. Adding graded levels of corn to the sucrose-fish meal ration and fish meal to the corn-soybean meal ration reduced vanadium toxicity. The corn fractions, ash, oil, starch, zein and gluten did not reduce vanadium toxicity. Removing the addedmore » magnesium (300 ppm) and potassium (2000 ppm) from the sucrose-fish meal ration did not affect growth rate or mortality. However removal of these materials from the basal ration increased growth depression due to added vanadium from 43-56% and increased mortality from 10-80%. 4 references, 9 tables.« less

Toxic Substances Registry System: Index of Material Safety Data Sheets. Volume 1; Manufacturer

NASA Technical Reports Server (NTRS)

1998-01-01

The April 1998 revision of the Index of Materials Safety Data Sheets (MSDS) for the Kennedy Space Center (KSC) Toxic Substances Registry System (TSRS) is presented. The MSDS lists toxic substances by manufacturer, trade name, stock number, and distributor. The index provides information on hazards, use, and chemical composition of materials stored at KSC.

Computational Molecular Modeling for Evaluating the Toxicity of Environmental Chemicals: Prioritizing Bioassay Requirements

EPA Science Inventory

This commentary provides an overview of the challenges that arise from applying molecular modeling tools developed and commonly used for pharmaceutical discovery to the problem of predicting the potential toxicities of environmental chemicals.

EPA's ToxCast Program for Predicting Hazard and Prioritizing the Toxicity Testing of Environmental Chemicals

EPA Science Inventory

An alternative is to perform a set of relatively inexpensive and rapid high throughput screening (HTS) assays, derive signatures predictive of effects or modes of chemical toxicity from the HTS data, then use these predictions to prioritize chemicals for more detailed analysis. T...

Probing the ToxCastTM Chemical Library for Predictive Signatures of Developmental Toxicity -NLTO Poster

EPA Science Inventory

EPA’s ToxCast™ project is profiling the in vitro bioactivity of chemical compounds to assess pathway-level and cell-based signatures that correlate with observed in vivo toxicity. We hypothesize that cell signaling pathways are primary targets for diverse environmental chemicals ...

Application of dispersive solid phase extraction for trace analysis of toxic chemicals in foods.

PubMed

Neely, Sarah; Martin, Jordan; da Cruz, Natalia Ferreira; Piester, Gavin; Robinson, Morgan; Okoniewski, Richard; Tran, Buu N

2018-05-29

The objectives of this study were to develop and validate a method for the identification of toxic organic chemicals, including groups of controlled substances, alkaloids and pesticides that are highly toxic and considered threats to public health. This project aims to ensure our laboratory's readiness to respond to emergencies involving our food supply in cooperation with the Food Emergency Response Network (FERN) program. The food matrices were homogenized in a blender or food processor prior to extraction with an acetonitrile-water mixture using a QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) procedure. The extracts were then analyzed by either gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-electrospray tandem mass spectrometry (LC-ESI/MS/MS). Method validation was performed on a variety of food matrices including lettuce, grapes, milk, chicken, pork and beef. MDLs for the toxic compounds ranged from 0.01 to 0.66 mg/kg (ppm). The findings in this study will provide a valuable resource for the determination of toxic chemicals in food matrices for emergency response situations. Copyright © 2018. Published by Elsevier B.V.

Sensitive detection of chemical agents and toxic industrial chemicals using active open-path FTIRs

NASA Astrophysics Data System (ADS)

Walter, William T.

2004-03-01

Active open-path FTIR sensors provide more sensitive detection of chemical agents than passive FTIRs, such as the M21 RSCAAL and JSLSCAD, and at the same time identify and quantify toxic industrial chemicals (TIC). Passive FTIRs are bistatic sensors relying on infrared sources of opportunity. Utilization of earth-based sources of opportunity limits the source temperatures available for passive chemical-agent FTIR sensors to 300° K. Active FTIR chemical-agent sensors utilize silicon carbide sources, which can be operated at 1500° K. The higher source temperature provides more than an 80-times increase in the infrared radiant flux emitted per unit area in the 7 to 14 micron spectral fingerprint region. Minimum detection limits are better than 5 μgm/m3 for GA, GB, GD, GF and VX. Active FTIR sensors can (1) assist first responders and emergency response teams in their assessment of and reaction to a terrorist threat, (2) provide information on the identification of the TIC present and their concentrations and (3) contribute to the understanding and prevention of debilitating disorders analogous to the Gulf War Syndrome for military and civilian personnel.

Isolation and characterization of Acidithiobacillus caldus from a sulfur-oxidizing bacterial biosensor and its role in detection of toxic chemicals.

PubMed

Hassan, Sedky H A; Van Ginkel, Steven W; Kim, Sung-Min; Yoon, Sung-Hwan; Joo, Jin-Ho; Shin, Beom-Soo; Jeon, Byong-Hun; Bae, Wookeun; Oh, Sang-Eun

2010-08-01

A novel toxicity detection methodology based on sulfur-oxidizing bacteria (SOB) has been developed for the rapid and reliable detection of toxic chemicals in water. The methodology exploits the ability of SOB to oxidize sulfur particles in the presence of oxygen to produce sulfuric acid. The reaction results in an increase in electrical conductivity (EC) and a decrease in pH. The assay is based on the inhibition of SOB in the presence of toxic chemicals by measuring changes in EC and pH. We found that SOB biosensor can detect toxic chemicals, such as heavy metals and CN-, in the 5-2000ppb range. One bacterium was isolated from an SOB biosensor and the 16S rRNA gene of the bacterial strain has 99% and 96% sequence similarity to Acidithiobacillus sp. ORCS6 and Acidithiobacillus caldus DSM 8584, respectively. The isolate was identified as A. caldus SMK. The SOB biosensor is ideally suited for monitoring toxic chemicals in water having the advantages of high sensitivity and quick detection.

Sources, mechanisms, and consequences of chemical-induced mitochondrial toxicity

PubMed Central

Meyer, Joel N.; Chan, Sherine S. L.

2017-01-01

Mitochondrial function is critical for health, as demonstrated by the effects of mitochondrial toxicity, mutations in genes encoding mitochondrial proteins, and the role of mitochondrial dysfunction in many chronic diseases. However, much basic mitochondrial biology is still being discovered. Furthermore, the details of how different environmental exposures affect mitochondria, how mitochondria respond to stressors, and how genetic variation affecting mitochondrial function alters response to exposures are areas of rapid research growth. This Special Issue was created to highlight and review cutting-edge areas of research into chemical effects on mitochondrial function. We anticipate that it will stimulate additional research into the mechanisms by which chemical exposures impact mitochondria, the biological processes that protect mitochondria from such impacts, and the health consequences that result when defense and homeostatic mechanisms are overcome. PMID:28627407

[Bioinorganic chemical composition of the lens and methods of its investigation].

PubMed

Avetisov, S E; Novikov, I A; Pakhomova, N A; Motalov, V G

2018-01-01

Bioinorganic chemical composition of the lens of human and experimental animals (cows, dogs, rats, rabbits) have been analyzed in various studies. In most cases, the studies employed different methods to determine the gross (total) composition of chemical elements and their concentrations in the examined samples. Less frequently, they included an assessment of the distribution of chemical elements in the lens and correlation of their concentration with its morphological changes. Chemical elements from all groups (series) of the periodic classification system were discovered in the lens substance. Despite similar investigation methods, different authors obtained contradicting results on the chemical composition of the lens. This article presents data suggesting possible correlation between inorganic chemical elements in the lens substance with the development and formation of lenticular opacities. All currently employed methods are known to only analyze limited number of select chemical elements in the tissues and do not consider the whole range of elements that can be analyzed with existing technology; furthermore, the majority of studies are conducted on the animal model lens. Therefore, it is feasible to continue the development of the chemical microanalysis method by increasing the sensitivity of Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) with the purpose of assessing the gross chemical composition and distribution of the elements in the lens substance, as well as revealing possible correlation between element concentration and morphological changes in the lens.

Predicting the Future: Opportunities and Challenges for the Chemical Industry to Apply 21st-Century Toxicity Testing

PubMed Central

Settivari, Raja S; Ball, Nicholas; Murphy, Lynea; Rasoulpour, Reza; Boverhof, Darrell R; Carney, Edward W

2015-01-01

Interest in applying 21st-century toxicity testing tools for safety assessment of industrial chemicals is growing. Whereas conventional toxicology uses mainly animal-based, descriptive methods, a paradigm shift is emerging in which computational approaches, systems biology, high-throughput in vitro toxicity assays, and high-throughput exposure assessments are beginning to be applied to mechanism-based risk assessments in a time- and resource-efficient fashion. Here we describe recent advances in predictive safety assessment, with a focus on their strategic application to meet the changing demands of the chemical industry and its stakeholders. The opportunities to apply these new approaches is extensive and include screening of new chemicals, informing the design of safer and more sustainable chemical alternatives, filling information gaps on data-poor chemicals already in commerce, strengthening read-across methodology for categories of chemicals sharing similar modes of action, and optimizing the design of reduced-risk product formulations. Finally, we discuss how these predictive approaches dovetail with in vivo integrated testing strategies within repeated-dose regulatory toxicity studies, which are in line with 3Rs principles to refine, reduce, and replace animal testing. Strategic application of these tools is the foundation for informed and efficient safety assessment testing strategies that can be applied at all stages of the product-development process. PMID:25836969

Predicting the future: opportunities and challenges for the chemical industry to apply 21st-century toxicity testing.

PubMed

Settivari, Raja S; Ball, Nicholas; Murphy, Lynea; Rasoulpour, Reza; Boverhof, Darrell R; Carney, Edward W

2015-03-01

Interest in applying 21st-century toxicity testing tools for safety assessment of industrial chemicals is growing. Whereas conventional toxicology uses mainly animal-based, descriptive methods, a paradigm shift is emerging in which computational approaches, systems biology, high-throughput in vitro toxicity assays, and high-throughput exposure assessments are beginning to be applied to mechanism-based risk assessments in a time- and resource-efficient fashion. Here we describe recent advances in predictive safety assessment, with a focus on their strategic application to meet the changing demands of the chemical industry and its stakeholders. The opportunities to apply these new approaches is extensive and include screening of new chemicals, informing the design of safer and more sustainable chemical alternatives, filling information gaps on data-poor chemicals already in commerce, strengthening read-across methodology for categories of chemicals sharing similar modes of action, and optimizing the design of reduced-risk product formulations. Finally, we discuss how these predictive approaches dovetail with in vivo integrated testing strategies within repeated-dose regulatory toxicity studies, which are in line with 3Rs principles to refine, reduce, and replace animal testing. Strategic application of these tools is the foundation for informed and efficient safety assessment testing strategies that can be applied at all stages of the product-development process.

Relationship between chemical composition and pulmonary toxicity of source-specific ambient particulate matter

EPA Science Inventory

Epidemiological studies have reported incidence of cardio-pulmonary disease associated with increase in particulate matter (PM) exposure. In this study, the pulmonary toxicity potential of combustion and ambient PM were investigated using data from animal studies at the US EPA....

Non-toxic invert analog glass compositions of high modulus

NASA Technical Reports Server (NTRS)

Bacon, J. F. (Inventor)

1974-01-01

Glass compositions having a Young's modulus of at least 15 million psi are described. They and a specific modulus of at least 110 million inches consist essentially of, in mols, 15 to 40% SiO2, 6 to 15% Li2O, 24 to 45% of at least two bivalent oxides selected from the group consisting of Ca, NzO, MgO and CuO; 13 to 39% of at least two trivalent oxides selected from the group consisting of Al2O3, Fe2O3, B2O3, La2O3, and Y2O3 and up to 15% of one or more tetravelent oxides selected from the group consisting of ZrO2, TiO2 and CeO2. The high modulus, low density glass compositions contain no toxic elements. The composition, glass density, Young's modulus, and specific modulus for 28 representative glasses are presented. The fiber modulus of five glasses are given.

Chemical composition, acute toxicity, and antinociceptive activity of the essential oil of a plant breeding cultivar of basil (Ocimum basilicum L.).

PubMed

Venâncio, Antônio Medeiros; Onofre, Alexandre Sherlley; Lira, Amintas Figueiredo; Alves, Péricles Barreto; Blank, Arie Fitzgerald; Antoniolli, Angelo Roberto; Marchioro, Murilo; Estevam, Charles dos Santos; de Araujo, Brancilene Santos

2011-05-01

Ocimum basilicum L. is an aromatic herb used in Brazil to treat illnesses such as respiratory and rheumatic problems, vomiting, and pain. In the present study, the chemical composition, acute toxicity, and antinociceptive effects of the essential oil (EO) of the cultivar "Maria Bonita" obtained from O. basilicum L. PI 197442 genotype were evaluated in Swiss mice (20-35 g each). Lethal dose to cause 50 % death (LD50) was calculated from a dose-response curve (100-5000 mg/kg body wt.; n = 6) as 532 mg/kg body wt. In the acetic acid-induced writhing test (0.6 % i. p.), EO (50, 100, and 200 mg/kg body wt., n = 8, s. c.) was effective in reducing the abdominal contractions at all doses (48-78 %). In the hot-plate test, EO significantly increased the latency at 50 mg/kg body wt. at all times (37-52 %, n = 8, s. c.). However, the effects of morphine and EO at 50 mg/kg were reverted in the presence of naloxone, an opioid antagonist. In the formalin test, EO significantly reduced paw licking time in the first and second phases of pain at 200 mg/kg body wt. (38 and 75 %, respectively, n = 8, s. c.). The results suggested that the peripheral and central antinociceptive effects of EO are related to the inhibition of the biosynthesis of pain mediators, such as prostaglandins and prostacyclins, and its ability to interact with opioid receptors. © Georg Thieme Verlag KG Stuttgart · New York.

Diet composition exacerbates or attenuates soman toxicity in rats: implied metabolic control of nerve agent toxicity.

PubMed

Myers, Todd M; Langston, Jeffrey L

2011-06-01

To evaluate the role of diet composition on nerve agent toxicity, rats were fed four distinct diets ad libitum for 28 d prior to challenge with 110 μg/kg (1.0 LD(50), sc) soman. The four diets used were a standard rodent diet, a choline-enriched diet, a glucose-enriched diet, and a ketogenic diet. Body weight was recorded throughout the study. Toxic signs and survival were evaluated at key times for up to 72 h following soman exposure. Additionally, acquisition of discriminated shuttlebox avoidance performance was characterized beginning 24h after soman challenge and across the next 8 d (six behavioral sessions). Prior to exposure, body weight was highest in the standard diet group and lowest in the ketogenic diet group. Upon exposure, differences in soman toxicity as a function of diet became apparent within the first hour, with mortality in the glucose-enriched diet group reaching 80% and exceeding all other groups (in which mortality ranged from 0 to 6%). At 72 h after exposure, mortality was 100% in the glucose-enriched diet group, and survival approximated 50% in the standard and choline-enriched diet groups, but equaled 87% in the ketogenic diet group. Body weight loss was significantly reduced in the ketogenic and choline-enriched diet groups, relative to the standard diet group. At 1 and 4h after exposure, rats in the ketogenic diet group had significantly lower toxic sign scores than all other groups. The ketogenic diet group performed significantly better than the standard diet group on two measures of active avoidance performance. The exacerbated soman toxicity observed in the glucose-enriched diet group coupled with the attenuated soman toxicity observed in the ketogenic diet group implicates glucose availability in the toxic effects of soman. This increased glucose availability may enhance acetylcholine synthesis and/or utilization, thereby exacerbating peripheral and central soman toxicity. Published by Elsevier B.V.

Acute toxicity of fire-retardant and foam-suppressant chemicals to early life stages of chinook salmon (Oncorhynchus tshawytscha)

USGS Publications Warehouse

Buhl, Kevin J.; Hamilton, Steven J.

1998-01-01

Laboratorys studies were conducted to determine the acute toxicity of three fire retardants (Fire-Trol GTS-R, Fire-Trol LCG-R, and Phos-Chek D75-F), and two fire-suppressant foams (Phos-Chek WD-881 and Ansul Silv-Ex) to early life stages of chinook salmon, Oncorhynchus tshawytscha, in hard and soft water. Regardless of water type, swim-up fry and juveniles (60 and 90 d posthatch) exhibited similar sensitivities to each chemical and these life stages were more sensitive than eyed eggs. Foam suppressants were more toxic to each life stage than the fire retardants in both water types. The descending rank order of toxicity for these chemicals tested with swim-up fry and juveniles (range of 96-h median lethal concentrations [LC50s]) was Phos-Chek WD-881 (7–13 mg/L) > Ansul Silv-Ex (11–22 mg/L) > Phos-Chek D75-F (218–305 mg/L) > Fire-Trol GTS-R (218–412 mg/L) > Fire-Trol LCG-R (685–1,195 mg/L). Water type had a minor effect on the toxicity of these chemicals. Comparison of acute toxicity values with recommended application concentrations indicates that accidental inputs of these chemicals into stream environments would require substantial dilution (237- to 1,429-fold) to reach concentrations equivalent to their 96-h LC50s.

EPA'S TOXCAST PROGRAM FOR PREDICTING HAZARD AND PRIORITIZING TOXICITY TESTING OF ENVIRONMENTAL CHEMICALS

EPA Science Inventory

EPA is developing methods for utilizing computational chemistry, high-throughput screening (HTS) and various toxicogenomic technologies to predict potential for toxicity and prioritize limited testing resources towards chemicals that likely represent the greatest hazard to human ...

A high-throughput method for assessing chemical toxicity using a Caenorhabditis elegans reproduction assay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyd, Windy A.; McBride, Sandra J.; Rice, Julie R.

2010-06-01

The National Research Council has outlined the need for non-mammalian toxicological models to test the potential health effects of a large number of chemicals while also reducing the use of traditional animal models. The nematode Caenorhabditis elegans is an attractive alternative model because of its well-characterized and evolutionarily conserved biology, low cost, and ability to be used in high-throughput screening. A high-throughput method is described for quantifying the reproductive capacity of C. elegans exposed to chemicals for 48 h from the last larval stage (L4) to adulthood using a COPAS Biosort. Initially, the effects of exposure conditions that could influencemore » reproduction were defined. Concentrations of DMSO vehicle {<=} 1% did not affect reproduction. Previous studies indicated that C. elegans may be influenced by exposure to low pH conditions. At pHs greater than 4.5, C. elegans reproduction was not affected; however below this pH there was a significant decrease in the number of offspring. Cadmium chloride was chosen as a model toxicant to verify that automated measurements were comparable to those of traditional observational studies. EC{sub 50} values for cadmium for automated measurements (176-192 {mu}M) were comparable to those previously reported for a 72-h exposure using manual counting (151 {mu}M). The toxicity of seven test toxicants on C. elegans reproduction was highly correlative with rodent lethality suggesting that this assay may be useful in predicting the potential toxicity of chemicals in other organisms.« less

In silico prediction of Tetrahymena pyriformis toxicity for diverse industrial chemicals with substructure pattern recognition and machine learning methods.

PubMed

Cheng, Feixiong; Shen, Jie; Yu, Yue; Li, Weihua; Liu, Guixia; Lee, Philip W; Tang, Yun

2011-03-01

There is an increasing need for the rapid safety assessment of chemicals by both industries and regulatory agencies throughout the world. In silico techniques are practical alternatives in the environmental hazard assessment. It is especially true to address the persistence, bioaccumulative and toxicity potentials of organic chemicals. Tetrahymena pyriformis toxicity is often used as a toxic endpoint. In this study, 1571 diverse unique chemicals were collected from the literature and composed of the largest diverse data set for T. pyriformis toxicity. Classification predictive models of T. pyriformis toxicity were developed by substructure pattern recognition and different machine learning methods, including support vector machine (SVM), C4.5 decision tree, k-nearest neighbors and random forest. The results of a 5-fold cross-validation showed that the SVM method performed better than other algorithms. The overall predictive accuracies of the SVM classification model with radial basis functions kernel was 92.2% for the 5-fold cross-validation and 92.6% for the external validation set, respectively. Furthermore, several representative substructure patterns for characterizing T. pyriformis toxicity were also identified via the information gain analysis methods. Copyright © 2010 Elsevier Ltd. All rights reserved.

QSTR of the toxicity of some organophosphorus compounds by using the quantum chemical and topological descriptors.

PubMed

Senior, Samir A; Madbouly, Magdy D; El massry, Abdel-Moneim

2011-09-01

Quantum chemical and topological descriptors of some organophosphorus compounds (OP) were correlated with their toxicity LD(50) as a dermal. The quantum chemical parameters were obtained using B3LYP/LANL2DZdp-ECP optimization. Using linear regression analysis, equations were derived to calculate the theoretical LD(50) of the studied compounds. The inclusion of quantum parameters, having both charge indices and topological indices, affects the toxicity of the studied compounds resulting in high correlation coefficient factors for the obtained equations. Two of the new four firstly supposed descriptors give higher correlation coefficients namely the Heteroatom Corrected Extended Connectivity Randic index ((1)X(HCEC)) and the Density Randic index ((1)X(Den)). The obtained linear equations were applied to predict the toxicity of some related structures. It was found that the sulfur atoms in these compounds must be replaced by oxygen atoms to achieve improved toxicity. Copyright © 2011 Elsevier Ltd. All rights reserved.

Identification of Chemical Vascular Disruptors During Development Using An Integrative Predictive Toxicity Model and Zebrafish and in Vitro Functional Angiogenesis Assays.

EPA Science Inventory

Identification of chemical vascular disruptors during development using an integrative predictive toxicity model and zebrafish and in vitro functional angiogenesis assays Chemically-induced vascular toxicity during embryonic development can result in a wide range of adverse pre...

Accurate prediction of acute fish toxicity of fragrance chemicals with the RTgill-W1 cell assay.

PubMed

Natsch, Andreas; Laue, Heike; Haupt, Tina; von Niederhäusern, Valentin; Sanders, Gordon

2018-03-01

Testing for acute fish toxicity is an integral part of the environmental safety assessment of chemicals. A true replacement of primary fish tissue was recently proposed using cell viability in a fish gill cell line (RTgill-W1) as a means of predicting acute toxicity, showing good predictivity on 35 chemicals. To promote regulatory acceptance, the predictivity and applicability domain of novel tests need to be carefully evaluated on chemicals with existing high-quality in vivo data. We applied the RTgill-W1 cell assay to 38 fragrance chemicals with a wide range of both physicochemical properties and median lethal concentration (LC50) values and representing a diverse range of chemistries. A strong correlation (R 2  = 0.90-0.94) between the logarithmic in vivo LC50 values, based on fish mortality, and the logarithmic in vitro median effect concentration (EC50) values based on cell viability was observed. A leave-one-out analysis illustrates a median under-/overprediction from in vitro EC50 values to in vivo LC50 values by a factor of 1.5. This assay offers a simple, accurate, and reliable alternative to in vivo acute fish toxicity testing for chemicals, presumably acting mainly by a narcotic mode of action. Furthermore, the present study provides validation of the predictivity of the RTgill-W1 assay on a completely independent set of chemicals that had not been previously tested and indicates that fragrance chemicals are clearly within the applicability domain. Environ Toxicol Chem 2018;37:931-941. © 2017 SETAC. © 2017 SETAC.

Effects of toxic chemicals on the reproductive system. Council on Scientific Affairs.

PubMed

1985-06-21

In an effort to make physicians more aware of the hazards of the workplace to pregnant workers, the Council on Scientific Affairs' Advisory Panel on Reproductive Hazards in the Workplace prepared this third and final report reviewing the effects of chemical exposure. A total of 120 chemicals were considered for reviews based on an estimation of their imminent hazard, ie, widespread use and/or inherent toxicity. Following a brief introduction, which sets out general principles, clinical applications, and aids to the recognition of a human teratogen, the report presents reviews and opinions for three representative chemicals. Information concerning the remaining 117 compounds is available upon request.

Dynamic development of the protein corona on silica nanoparticles: composition and role in toxicity

NASA Astrophysics Data System (ADS)

Mortensen, Ninell P.; Hurst, Gregory B.; Wang, Wei; Foster, Carmen M.; Nallathamby, Prakash D.; Retterer, Scott T.

2013-06-01

The formation and composition of the protein corona on silica (SiO2) nanoparticles (NP) with different surface chemistries was evaluated over time. Native SiO2, amine (-NH2) and carboxy (-COO-) modified NP were examined following incubation in mammalian growth media containing fetal bovine serum (FBS) for 1, 4, 24 and 48 hours. The protein corona transition from its early dynamic state to the later more stable corona was evaluated using mass spectrometry. The NP diameter was 22.4 +/- 2.2 nm measured by scanning transmission electron microscopy (STEM). Changes in hydrodynamic diameter and agglomeration kinetics were studied using dynamic light scattering (DLS). The initial surface chemistry of the NP played an important role in the development and final composition of the protein corona, impacting agglomeration kinetics and NP toxicity. Particle toxicity, indicated by changes in membrane integrity and mitochondrial activity, was measured by lactate dehydrogenase (LDH) release and tetrazolium reduction (MTT), respectively, in mouse alveolar macrophages (RAW264.7) and mouse lung epithelial cells (C10). SiO2-COO- NP had a slower agglomeration rate, formed smaller aggregates, and exhibited lower cytotoxicity compared to SiO2 and SiO2-NH2. Composition of the protein corona for each of the three NP was unique, indicating a strong dependence of corona development on NP surface chemistry. This work underscores the need to understand all aspects of NP toxicity, particularly the influence of agglomeration on effective dose and particle size. Furthermore, the interplay between materials and local biological environment is emphasized and highlights the need to conduct toxicity profiling under physiologically relevant conditions that provide an appropriate estimation of material modifications that occur during exposure in natural environments.The formation and composition of the protein corona on silica (SiO2) nanoparticles (NP) with different surface chemistries was evaluated

Identifying developmental toxicity pathways for a subset of ToxCast chemicals using human embryonic stem cells and metabolomics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kleinstreuer, N.C., E-mail: kleinstreuer.nicole@epa.gov; Smith, A.M.; West, P.R.

2011-11-15

Metabolomics analysis was performed on the supernatant of human embryonic stem (hES) cell cultures exposed to a blinded subset of 11 chemicals selected from the chemical library of EPA's ToxCast Trade-Mark-Sign chemical screening and prioritization research project. Metabolites from hES cultures were evaluated for known and novel signatures that may be indicative of developmental toxicity. Significant fold changes in endogenous metabolites were detected for 83 putatively annotated mass features in response to the subset of ToxCast chemicals. The annotations were mapped to specific human metabolic pathways. This revealed strong effects on pathways for nicotinate and nicotinamide metabolism, pantothenate and CoAmore » biosynthesis, glutathione metabolism, and arginine and proline metabolism pathways. Predictivity for adverse outcomes in mammalian prenatal developmental toxicity studies used ToxRefDB and other sources of information, including Stemina Biomarker Discovery's predictive DevTox Registered-Sign model trained on 23 pharmaceutical agents of known developmental toxicity and differing potency. The model initially predicted developmental toxicity from the blinded ToxCast compounds in concordance with animal data with 73% accuracy. Retraining the model with data from the unblinded test compounds at one concentration level increased the predictive accuracy for the remaining concentrations to 83%. These preliminary results on a 11-chemical subset of the ToxCast chemical library indicate that metabolomics analysis of the hES secretome provides information valuable for predictive modeling and mechanistic understanding of mammalian developmental toxicity. -- Highlights: Black-Right-Pointing-Pointer We tested 11 environmental compounds in a hESC metabolomics platform. Black-Right-Pointing-Pointer Significant changes in secreted small molecule metabolites were observed. Black-Right-Pointing-Pointer Perturbed mass features map to pathways critical for normal

Impact of environmentally based chemical hardness on uranium speciation and toxicity in six aquatic species.

PubMed

Goulet, Richard R; Thompson, Patsy A; Serben, Kerrie C; Eickhoff, Curtis V

2015-03-01

Treated effluent discharge from uranium (U) mines and mills elevates the concentrations of U, calcium (Ca), magnesium (Mg), and sulfate (SO4 (2-) ) above natural levels in receiving waters. Many investigations on the effect of hardness on U toxicity have been experiments on the combined effects of changes in hardness, pH, and alkalinity, which do not represent water chemistry downstream of U mines and mills. Therefore, more toxicity studies with water chemistry encountered downstream of U mines and mills are necessary to support predictive assessments of impacts of U discharge to the environment. Acute and chronic U toxicity laboratory bioassays were realized with 6 freshwater species in waters of low alkalinity, circumneutral pH, and a range of chemical hardness as found in field samples collected downstream of U mines and mills. In laboratory-tested waters, speciation calculations suggested that free uranyl ion concentrations remained constant despite increasing chemical hardness. When hardness increased while pH remained circumneutral and alkalinity low, U toxicity decreased only to Hyalella azteca and Pseudokirchneriella subcapitata. Also, Ca and Mg did not compete with U for the same uptake sites. The present study confirms that the majority of studies concluding that hardness affected U toxicity were in fact studies in which alkalinity and pH were the stronger influence. The results thus confirm that studies predicting impacts of U downstream of mines and mills should not consider chemical hardness. Environ Toxicol Chem 2015;34:562-574. © 2014 The Authors. Published by Wiley Periodicals, Inc. on behalf of SETAC. © 2014 The Authors. Published by Wiley Periodicals, Inc. on behalf of SETAC.

Toxicity of inorganic nanomaterials in biomedical imaging.

PubMed

Li, Jinxia; Chang, Xueling; Chen, Xiaoxia; Gu, Zhanjun; Zhao, Feng; Chai, Zhifang; Zhao, Yuliang

2014-01-01

Inorganic nanoparticles have shown promising potentials as novel biomedical imaging agents with high sensitivity, high spatial and temporal resolution. To translate the laboratory innovations into clinical applications, their potential toxicities are highly concerned and have to be evaluated comprehensively both in vitro and in vivo before their clinical applications. In this review, we first summarized the in vivo and in vitro toxicities of the representative inorganic nanoparticles used in biomedical imagings. Then we further discuss the origin of nanotoxicity of inorganic nanomaterials, including ROS generation and oxidative stress, chemical instability, chemical composition, the surface modification, dissolution of nanoparticles to release excess free ions of metals, metal redox state, and left-over chemicals from synthesis, etc. We intend to provide the readers a better understanding of the toxicology aspects of inorganic nanomaterials and knowledge for achieving optimized designs of safer inorganic nanomaterials for clinical applications. Copyright © 2014 Elsevier Inc. All rights reserved.

Fact Sheet: Final Air Toxics Standards for Area Sources in the Chemical Manufacturing Industry

EPA Pesticide Factsheets

Fact sheet on the national air toxics standards issued October 16, 2009 by the Environmental Protection Agency (EPA) for smaller-emitting sources, known as area sources, in the chemical manufacturing industry.

Average chemical composition of the lunar surface

NASA Technical Reports Server (NTRS)

Turkevich, A. L.

1973-01-01

The available data on the chemical composition of the lunar surface at eleven sites (3 Surveyor, 5 Apollo and 3 Luna) are used to estimate the amounts of principal chemical elements (those present in more than about 0.5% by atom) in average lunar surface material. The terrae of the moon differ from the maria in having much less iron and titanium and appreciably more aluminum and calcium.

Chemical composition, efficacy and safety of Pistacia vera (var. Fandoghi) to inactivate protoscoleces during hydatid cyst surgery.

PubMed

Mahmoudvand, Hossein; Kheirandish, Farnaz; Dezaki, Ebrahim Saedi; Shamsaddini, Saeedeh; Harandi, Majid Fasihi

2016-08-01

At present, various scolicidal agents have been used for inactivation of protoscoleces during hydatid cyst surgery, however, they are associated with serious adverse side effects including sclerosing colangititis (biliary tract fibrosis), liver necrosis and methaemoglobinaemia. This investigation was designed to evaluate the chemical composition and in vitro scolicidal effects of Pistacia vera (var. Fandoghi) essential oil against protoscoleces of hydatid cysts and also its toxicity in mice model. The components of the P. vera essential oil were identified by gas chromatography/mass spectroscopy (GC/MS) analysis. Protoscoleces were aseptically aspirated from sheep livers having hydatid cysts. Various concentrations of the essential oil (25-200μl/mL) were used for 5-30min. Viability of protoscoleces was confirmed using eosin exclusion test (0.1% eosin staining). In addition, forty male NIH mice were used to determine the acute and sub-acute toxicity of P. vera essential oil for 2 and 14 days, respectively. The main components of P. vera essential oil were limonene (26.21%), α-pinene (18.07%), α-thujene (9.31%) and α-terpinolene (9.28%). Findings of the present study demonstrated that the P. vera essential oil at the concentrations of 100 and 200μl/mL killed 100% protoscoleces after 10 and 5min of exposure, respectively. The LD50 values of intraperitoneal injection of the P. vera essential oil was 2.69ml/kg body weight, and the maximum nonfatal doses were 1.94ml/kg body weight. No significant difference (P>0.05) was observed in the clinical chemistry and hematological parameters following oral administrations of P. vera essential oil at the doses 0.1, 0.2, and 0.4ml/kg for 14 days. The obtained findings demonstrated new chemical composition and promising scolicidal activity of the P. vera with no significant toxicity which might be used as a natural scolicidal agent in hydatid cyst surgery. Copyright © 2016. Published by Elsevier Masson SAS.

ToxRefDB: Classifying ToxCast™ Phase I Chemicals Utilizing Structured Toxicity Information

EPA Science Inventory

There is an essential need for highly detailed chemicals classifications within the ToxCast™ research program. In order to develop predictive models and biological signatures utilizing high-throughput screening (HTS) and in vitro genomic data, relevant endpoints and toxicities m...

Seasonal alterations of landfill leachate composition and toxic potency in semi-arid regions.

PubMed

Tsarpali, Vasiliki; Kamilari, Maria; Dailianis, Stefanos

2012-09-30

The present study investigates seasonal variations of leachate composition and its toxic potency on different species, such as the brine shrimp Artemia franciscana (formerly Artemia salina), the fairy shrimp Thamnocephalus platyurus, the estuarine rotifer Brachionus plicatilis and the microalgal flagellate Dunaliella tertiolecta. In specific, leachate regularly collected from the municipal landfill site of Aigeira (Peloponissos, Greece) during the year 2011, showed significant alterations of almost all its physicochemical parameters with time. Further analysis showed that seasonal alterations of leachate composition are related with the amount of rainfall obtained throughout the year. In fact, rainfall-related parameters, such as conductivity (Cond), nitrates (NO(3)(-)), total nitrogen (TN), ammonium (NH(4)-N), total dissolved solids (TDS) and the BOD(5)/NH(4)-N ratio could merely reflect the leachate strength and toxicity, as verified by the significant correlations occurred among each of them with the toxic endpoints, 24 h LC(50) and/or 72 h IC(50), obtained in all species tested. According to the result of the present study, it could be suggested that the aforementioned leachate parameters could be used independently, or in combination as a low-cost effective tools for estimating leachate strength and toxic potency, at least in the case of semi-arid areas such as the most of the Mediterranean countries. Copyright © 2012 Elsevier B.V. All rights reserved.

Estimating the Potential Toxicity of Chemicals Associated with Hydraulic Fracturing Operations Using Quantitative Structure-Activity Relationship Modeling.

PubMed

Yost, Erin E; Stanek, John; DeWoskin, Robert S; Burgoon, Lyle D

2016-07-19

The United States Environmental Protection Agency (EPA) identified 1173 chemicals associated with hydraulic fracturing fluids, flowback, or produced water, of which 1026 (87%) lack chronic oral toxicity values for human health assessments. To facilitate the ranking and prioritization of chemicals that lack toxicity values, it may be useful to employ toxicity estimates from quantitative structure-activity relationship (QSAR) models. Here we describe an approach for applying the results of a QSAR model from the TOPKAT program suite, which provides estimates of the rat chronic oral lowest-observed-adverse-effect level (LOAEL). Of the 1173 chemicals, TOPKAT was able to generate LOAEL estimates for 515 (44%). To address the uncertainty associated with these estimates, we assigned qualitative confidence scores (high, medium, or low) to each TOPKAT LOAEL estimate, and found 481 to be high-confidence. For 48 chemicals that had both a high-confidence TOPKAT LOAEL estimate and a chronic oral reference dose from EPA's Integrated Risk Information System (IRIS) database, Spearman rank correlation identified 68% agreement between the two values (permutation p-value =1 × 10(-11)). These results provide support for the use of TOPKAT LOAEL estimates in identifying and prioritizing potentially hazardous chemicals. High-confidence TOPKAT LOAEL estimates were available for 389 of 1026 hydraulic fracturing-related chemicals that lack chronic oral RfVs and OSFs from EPA-identified sources, including a subset of chemicals that are frequently used in hydraulic fracturing fluids.

History of EPI Suite™ and future perspectives on chemical property estimation in US Toxic Substances Control Act new chemical risk assessments.

PubMed

Card, Marcella L; Gomez-Alvarez, Vicente; Lee, Wen-Hsiung; Lynch, David G; Orentas, Nerija S; Lee, Mari Titcombe; Wong, Edmund M; Boethling, Robert S

2017-03-22

Chemical property estimation is a key component in many industrial, academic, and regulatory activities, including in the risk assessment associated with the approximately 1000 new chemical pre-manufacture notices the United States Environmental Protection Agency (US EPA) receives annually. The US EPA evaluates fate, exposure and toxicity under the 1976 Toxic Substances Control Act (amended by the 2016 Frank R. Lautenberg Chemical Safety for the 21 st Century Act), which does not require test data with new chemical applications. Though the submission of data is not required, the US EPA has, over the past 40 years, occasionally received chemical-specific data with pre-manufacture notices. The US EPA has been actively using this and publicly available data to develop and refine predictive computerized models, most of which are housed in EPI Suite™, to estimate chemical properties used in the risk assessment of new chemicals. The US EPA develops and uses models based on (quantitative) structure-activity relationships ([Q]SARs) to estimate critical parameters. As in any evolving field, (Q)SARs have experienced successes, suffered failures, and responded to emerging trends. Correlations of a chemical structure with its properties or biological activity were first demonstrated in the late 19 th century and today have been encapsulated in a myriad of quantitative and qualitative SARs. The development and proliferation of the personal computer in the late 20 th century gave rise to a quickly increasing number of property estimation models, and continually improved computing power and connectivity among researchers via the internet are enabling the development of increasingly complex models.

Zebrafish Get Connected: Investigating Neurotransmission Targets and Alterations in Chemical Toxicity

PubMed Central

Horzmann, Katharine A.; Freeman, Jennifer L.

2016-01-01

Neurotransmission is the basis of neuronal communication and is critical for normal brain development, behavior, learning, and memory. Exposure to drugs and chemicals can alter neurotransmission, often through unknown pathways and mechanisms. The zebrafish (Danio rerio) model system is increasingly being used to study the brain and chemical neurotoxicity. In this review, the major neurotransmitter systems, including glutamate, GABA, dopamine, norepinephrine, serotonin, acetylcholine, histamine, and glutamate are surveyed and pathways of synthesis, transport, metabolism, and action are examined. Differences between human and zebrafish neurochemical pathways are highlighted. We also review techniques for evaluating neurological function, including the measurement of neurotransmitter levels, assessment of gene expression through transcriptomic analysis, and the recording of neurobehavior. Finally examples of chemical toxicity studies evaluating alterations in neurotransmitter systems in the zebrafish model are reviewed. PMID:28730152

Identification of compounds in heavy fuel oil that are chronically toxic to rainbow trout embryos by effects-driven chemical fractionation.

PubMed

Adams, Julie; Bornstein, Jason M; Munno, Keenan; Hollebone, Bruce; King, Thomas; Brown, R Stephen; Hodson, Peter V

2014-04-01

The present study isolated and identified compounds in heavy fuel oil 7102 (HFO 7102) that are bioavailable and chronically toxic to rainbow trout embryos (Oncorhynchus mykiss). An effects-driven chemical fractionation combined the chemical separation of oil with toxicity testing and chemical analyses of each fraction to identify the major classes of compounds associated with embryo toxicity. Toxicity was assessed with 2 exposure methods, a high-energy chemical dispersion of oil in water, which included oil droplets in test solutions, and water accommodated fractions which were produced by oiled gravel desorption columns, and which did not contain visible oil droplets. Fractions of HFO with high concentrations of naphthalenes, alkanes, asphaltenes, and resins were nontoxic to embryos over the range of concentrations tested. In contrast, fractions enriched with 3- to 4-ringed alkyl polycyclic aromatic hydrocarbons (PAHs) were embryotoxic, consistent with published studies of crude oils and individual alkyl PAHs. The rank order of fraction toxicity did not vary between the exposure methods and was consistent with their PAH content; fractions with higher-molecular weight alkyl PAHs were the most toxic. Exposure of juvenile trout to most fractions of HFO induced higher activities of cytochrome P450 enzymes, with a rank order of potency that varied with exposure method and differed somewhat from that of embryotoxicity. Induction reflected the bioavailability of PAHs but did not accurately predict embryotoxicity. © 2013 SETAC.

In vitro investigation of oxide nanoparticle and carbon nanotube toxicity and intracellular accumulation in A549 human pneumocytes.

PubMed

Simon-Deckers, A; Gouget, B; Mayne-L'hermite, M; Herlin-Boime, N; Reynaud, C; Carrière, M

2008-11-20

If released in the environment, nanomaterials might be inhaled by populations and cause damage to the deepest regions of the respiratory tract, i.e., the alveolar compartment. To model this situation, we studied the response of A549 human pneumocytes after exposure to aluminium oxide or titanium oxide nanoparticles, and to multi-walled carbon nanotubes. The influence of size, crystalline structure and chemical composition was investigated. After a detailed identification of nanomaterial physico-chemical characteristics, cells were exposed in vitro and viability and intracellular accumulation were assessed. In our conditions, carbon nanotubes were more toxic than metal oxide nanoparticles. Our results confirmed that both nanotubes and nanoparticles are able to rapidly enter into cells, and distribute in the cytoplasm and intracellular vesicles. Among nanoparticles, we demonstrate significant difference in biological response as a function of size, crystalline phase and chemical composition. Their toxicity was globally lower than nanotubes toxicity. Among nanotubes, the length did not influence cytotoxicity, neither the presence of metal catalyst impurities.

Modelling the Tox21 10 K chemical profiles for in vivo toxicity prediction and mechanism characterization

PubMed Central

Huang, Ruili; Xia, Menghang; Sakamuru, Srilatha; Zhao, Jinghua; Shahane, Sampada A.; Attene-Ramos, Matias; Zhao, Tongan; Austin, Christopher P.; Simeonov, Anton

2016-01-01

Target-specific, mechanism-oriented in vitro assays post a promising alternative to traditional animal toxicology studies. Here we report the first comprehensive analysis of the Tox21 effort, a large-scale in vitro toxicity screening of chemicals. We test ∼10,000 chemicals in triplicates at 15 concentrations against a panel of nuclear receptor and stress response pathway assays, producing more than 50 million data points. Compound clustering by structure similarity and activity profile similarity across the assays reveals structure–activity relationships that are useful for the generation of mechanistic hypotheses. We apply structural information and activity data to build predictive models for 72 in vivo toxicity end points using a cluster-based approach. Models based on in vitro assay data perform better in predicting human toxicity end points than animal toxicity, while a combination of structural and activity data results in better models than using structure or activity data alone. Our results suggest that in vitro activity profiles can be applied as signatures of compound mechanism of toxicity and used in prioritization for more in-depth toxicological testing. PMID:26811972

Guidance on health effects of toxic chemicals. Safety Analysis Report Update Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foust, C.B.; Griffin, G.D.; Munro, N.B.

1994-02-01

Martin Marietta Energy Systems, Inc. (MMES), and Martin Marietta Utility Services, Inc. (MMUS), are engaged in phased programs to update the safety documentation for the existing US Department of Energy (DOE)-owned facilities. The safety analysis of potential toxic hazards requires a methodology for evaluating human health effects of predicted toxic exposures. This report provides a consistent set of health effects and documents toxicity estimates corresponding to these health effects for some of the more important chemicals found within MMES and MMUS. The estimates are based on published toxicity information and apply to acute exposures for an ``average`` individual. The healthmore » effects (toxicological endpoints) used in this report are (1) the detection threshold; (2) the no-observed adverse effect level; (3) the onset of irritation/reversible effects; (4) the onset of irreversible effects; and (5) a lethal exposure, defined to be the 50% lethal level. An irreversible effect is defined as a significant effect on a person`s quality of life, e.g., serious injury. Predicted consequences are evaluated on the basis of concentration and exposure time.« less

Chemical composition of wildland fire emissions

Treesearch

Shawn P. Urbanski; Wei Min Hao; Stephen Baker

2009-01-01

Wildland fires are major sources of trace gases and aerosol, and these emissions are believed to significantly influence the chemical composition of the atmosphere and the earth's climate system. The wide variety of pollutants released by wildland fire include greenhouse gases, photochemically reactive compounds, and fine and coarse particulate matter. Through...

The role of dissolved organic carbon concentration and composition on nickel toxicity to early life-stages of the blue mussel Mytilus edulis and purple sea urchin Strongylocentrotus purpuratus.

PubMed

Blewett, Tamzin A; Dow, Elissa M; Wood, Chris M; McGeer, James C; Smith, D Scott

2018-05-24

Nickel (Ni) emissions resulting from production and transportation raise concerns about the impact of Ni exposure to marine ecosystems. Ni bioavailability models are established for FW systems, but the influence of chemical parameters (e.g. dissolved organic carbon (DOC)) on Ni toxicity within marine systems is less well understood. To examine the effects of DOC concentration and composition on Ni toxicity, acute toxicity tests were conducted on early life-stages of blue mussels (Mytilus edulis) and sea urchin embryos (Strongylocentrotus purpuratus) in full strength sea water (32 ppt). Nine different field collected samples of water with varying concentration (up to 4.5 mg C/L) and composition of DOC were collected from the east coast of the United States. Organic matter compositional analysis included molecular fluorescence and absorbance spectroscopy. The different DOC sources had different protective effects against embryo toxicity. The control (no DOC) Ni 48 h-EC 50 for Mytilus embryos was 133 µg/L (95% confidence interval (C.I.) of 123-144 µg/L), while Strongylocentrotus embryos displayed control 96-h EC 50 values of 207 µg/L (167-247 µg/L). The most significantly protective sample had high humic acid concentrations (as determined from fluorescence spectroscopy), which yielded an EC 50 of 195 µg/L (169-222 µg/L) for Mytilus, and an EC 50 of 394 µg/L (369-419 µg/L) for S. purpuratus. Among all samples, protection was related to both DOC quantity and quality, with fluorescence-resolved humic and fulvic acid concentrations showing the strongest correlations with protection for both species. These data suggest that DOC is protective against Ni toxicity in M. edulis and S. purpuratus, and that accounting for a DOC quality factor will improve predictive toxicity models such as the biotic ligand model. Copyright © 2018 Elsevier Inc. All rights reserved.

Optimizing Toxic Chemical Removal through Defect-Induced UiO-66-NH2 Metal-Organic Framework.

PubMed

Peterson, Gregory W; Destefano, Matthew R; Garibay, Sergio J; Ploskonka, Ann; McEntee, Monica; Hall, Morgan; Karwacki, Christopher J; Hupp, Joseph T; Farha, Omar K

2017-11-13

For the first time, an increasing number of defects were introduced to the metal-organic framework UiO-66-NH 2 in an attempt to understand the structure-activity trade-offs associated with toxic chemical removal. It was found that an optimum exists with moderate defects for toxic chemicals that react with the linker, whereas those that require hydrolysis at the secondary building unit performed better when more defects were introduced. The insights obtained through this work highlight the ability to dial-in appropriate material formulations, even within the same parent metal-organic framework, allowing for trade-offs between reaction efficiency and mass transfer. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel in vitro and mathematical models for the prediction of chemical toxicity.

PubMed

Williams, Dominic P; Shipley, Rebecca; Ellis, Marianne J; Webb, Steve; Ward, John; Gardner, Iain; Creton, Stuart

2013-01-01

The focus of much scientific and medical research is directed towards understanding the disease process and defining therapeutic intervention strategies. The scientific basis of drug safety is very complex and currently remains poorly understood, despite the fact that adverse drug reactions (ADRs) are a major health concern and a serious impediment to development of new medicines. Toxicity issues account for ∼21% drug attrition during drug development and safety testing strategies require considerable animal use. Mechanistic relationships between drug plasma levels and molecular/cellular events that culminate in whole organ toxicity underpins development of novel safety assessment strategies. Current in vitro test systems are poorly predictive of toxicity of chemicals entering the systemic circulation, particularly to the liver. Such systems fall short because of (1) the physiological gap between cells currently used and human hepatocytes existing in their native state, (2) the lack of physiological integration with other cells/systems within organs, required to amplify the initial toxicological lesion into overt toxicity, (3) the inability to assess how low level cell damage induced by chemicals may develop into overt organ toxicity in a minority of patients, (4) lack of consideration of systemic effects. Reproduction of centrilobular and periportal hepatocyte phenotypes in in vitro culture is crucial for sensitive detection of cellular stress. Hepatocyte metabolism/phenotype is dependent on cell position along the liver lobule, with corresponding differences in exposure to substrate, oxygen and hormone gradients. Application of bioartificial liver (BAL) technology can encompass in vitro predictive toxicity testing with enhanced sensitivity and improved mechanistic understanding. Combining this technology with mechanistic mathematical models describing intracellular metabolism, fluid-flow, substrate, hormone and nutrient distribution provides the opportunity to

Novel in vitro and mathematical models for the prediction of chemical toxicity

PubMed Central

Shipley, Rebecca; Ellis, Marianne J.; Webb, Steve; Ward, John; Gardner, Iain; Creton, Stuart

2013-01-01

The focus of much scientific and medical research is directed towards understanding the disease process and defining therapeutic intervention strategies. The scientific basis of drug safety is very complex and currently remains poorly understood, despite the fact that adverse drug reactions (ADRs) are a major health concern and a serious impediment to development of new medicines. Toxicity issues account for ∼21% drug attrition during drug development and safety testing strategies require considerable animal use. Mechanistic relationships between drug plasma levels and molecular/cellular events that culminate in whole organ toxicity underpins development of novel safety assessment strategies. Current in vitro test systems are poorly predictive of toxicity of chemicals entering the systemic circulation, particularly to the liver. Such systems fall short because of (1) the physiological gap between cells currently used and human hepatocytes existing in their native state, (2) the lack of physiological integration with other cells/systems within organs, required to amplify the initial toxicological lesion into overt toxicity, (3) the inability to assess how low level cell damage induced by chemicals may develop into overt organ toxicity in a minority of patients, (4) lack of consideration of systemic effects. Reproduction of centrilobular and periportal hepatocyte phenotypes in in vitro culture is crucial for sensitive detection of cellular stress. Hepatocyte metabolism/phenotype is dependent on cell position along the liver lobule, with corresponding differences in exposure to substrate, oxygen and hormone gradients. Application of bioartificial liver (BAL) technology can encompass in vitro predictive toxicity testing with enhanced sensitivity and improved mechanistic understanding. Combining this technology with mechanistic mathematical models describing intracellular metabolism, fluid-flow, substrate, hormone and nutrient distribution provides the opportunity to

Species-Specific Predictive Signatures of Developmental Toxicity Using the ToxCast Chemical Library

EPA Science Inventory

EPA’s ToxCastTM project is profiling the in vitro bioactivity of chemicals to generate predictive signatures that correlate with observed in vivo toxicity. In vitro profiling methods from ToxCast data consist of over 600 high-throughput screening (HTS) and high-content screening ...

CHEMICAL PRIORITIZATION FOR DEVELOPMENTAL TOXICITY USING LITERATURE MINING-BASED WEIGHTING OF TOXCAST ASSAYS

EPA Science Inventory

Defining a predictive model of developmental toxicity from in vitro and high-throughput screening (HTS) assays can be limited by the availability of developmental defects data. ToxRefDB (www.epa.gov/ncct/todrefdb) was built from animal studies on data-rich environmental chemicals...

MICHTOX: A MASS BALANCE AND BIOACCUMULATION MODEL FOR TOXIC CHEMICALS IN LAKE MICHIGAN

EPA Science Inventory

MICHTOX is a toxic chemical mass balance and bioaccumulation model for Lake Michigan. It was developed for USEPA's Region V in support of the Lake Michigan Lake-wide Management Plan (LaMP) to provide guidance on expected water quality improvements in response to critical pollutan...

Therapeutic values, chemical constituents and toxicity of Taiwanese Dysosma pleiantha--a review.

PubMed

Karuppaiya, Palaniyandi; Tsay, Hsin Sheng

2015-07-16

Dysosma pleiantha (Hance) Woodson also called as Bajiaolian belongs to the family Berberidaceae, is widely used in Taiwan as traditional Chinese herbal medicine for more than thousands of years. It is usually recommended by various traditional Chinese medical doctors and herbal pharmacies for general remedies including postpartum recovery, treatment of weakness, neck mass, acne, hepatoma, lumbago, snakebite, tumor growth and dysmenorrhea. In the textbooks of traditional Chinese medicine, there is limited information about the toxicity of Bajiaolian. Podophyllotoxin, a lignan is the main toxic ingredient of Bajiaolian rhizome. Therefore, Bajiaolian is documented as the fifth highest cause of poisoning among the herbal medicine in Taiwan. Since the therapeutic and toxic doses are very close, Bajiaolian poisoning cases are frequently reported in Taiwan. Moreover, Dysosma poisoning cases are difficult to diagnosis because physicians are unfamiliar with this medicine's multiple clinical presentations in different stages of intoxication. Therefore, the objective of this review is to represent the collective information available in literatures regarding D. pleiantha, a cytotoxic lignan containing medicinal plant. Specifically, the literatures have been reviewed for articles pertaining to chemical constituents, properties, therapeutical benefits, toxicity, poisoning symptoms, toxic as well as therapeutic dose and medical management. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Toxicity Screening of the ToxCast Phase II Chemical Library Using a Zebrafish Developmental Assay (SOT)

EPA Science Inventory

As part of the chemical screening and prioritization research program of the US EPA, the ToxCast Phase II chemicals were assessed using a vertebrate screen for developmental toxicity. Zebrafish embryos (Danio rerio) were exposed in 96-well plates from late-blastula stage (6hr pos...

General baseline toxicity QSAR for nonpolar, polar and ionisable chemicals and their mixtures in the bioluminescence inhibition assay with Aliivibrio fischeri.

PubMed

Escher, Beate I; Baumer, Andreas; Bittermann, Kai; Henneberger, Luise; König, Maria; Kühnert, Christin; Klüver, Nils

2017-03-22

The Microtox assay, a bioluminescence inhibition assay with the marine bacterium Aliivibrio fischeri, is one of the most popular bioassays for assessing the cytotoxicity of organic chemicals, mixtures and environmental samples. Most environmental chemicals act as baseline toxicants in this short-term screening assay, which is typically run with only 30 min of exposure duration. Numerous Quantitative Structure-Activity Relationships (QSARs) exist for the Microtox assay for nonpolar and polar narcosis. However, typical water pollutants, which have highly diverse structures covering a wide range of hydrophobicity and speciation from neutral to anionic and cationic, are often outside the applicability domain of these QSARs. To include all types of environmentally relevant organic pollutants we developed a general baseline toxicity QSAR using liposome-water distribution ratios as descriptors. Previous limitations in availability of experimental liposome-water partition constants were overcome by reliable prediction models based on polyparameter linear free energy relationships for neutral chemicals and the COSMOmic model for charged chemicals. With this QSAR and targeted mixture experiments we could demonstrate that ionisable chemicals fall in the applicability domain. Most investigated water pollutants acted as baseline toxicants in this bioassay, with the few outliers identified as uncouplers or reactive toxicants. The main limitation of the Microtox assay is that chemicals with a high melting point and/or high hydrophobicity were outside of the applicability domain because of their low water solubility. We quantitatively derived a solubility cut-off but also demonstrated with mixture experiments that chemicals inactive on their own can contribute to mixture toxicity, which is highly relevant for complex environmental mixtures, where these chemicals may be present at concentrations below the solubility cut-off.

Developing a list of reference chemicals for testing alternatives to whole fish toxicity tests.

PubMed

Schirmer, Kristin; Tanneberger, Katrin; Kramer, Nynke I; Völker, Doris; Scholz, Stefan; Hafner, Christoph; Lee, Lucy E J; Bols, Niels C; Hermens, Joop L M

2008-11-11

This paper details the derivation of a list of 60 reference chemicals for the development of alternatives to animal testing in ecotoxicology with a particular focus on fish. The chemicals were selected as a prerequisite to gather mechanistic information on the performance of alternative testing systems, namely vertebrate cell lines and fish embryos, in comparison to the fish acute lethality test. To avoid the need for additional experiments with fish, the U.S. EPA fathead minnow database was consulted as reference for whole organism responses. This database was compared to the Halle Registry of Cytotoxicity and a collation of data by the German EPA (UBA) on acute toxicity data derived from zebrafish embryos. Chemicals that were present in the fathead minnow database and in at least one of the other two databases were subject to selection. Criteria included the coverage of a wide range of toxicity and physico-chemical parameters as well as the determination of outliers of the in vivo/in vitro correlations. While the reference list of chemicals now guides our research for improving cell line and fish embryo assays to make them widely applicable, the list could be of benefit to search for alternatives in ecotoxicology in general. One example would be the use of this list to validate structure-activity prediction models, which in turn would benefit from a continuous extension of this list with regard to physico-chemical and toxicological data.

Chemical composition of fennel essential oil and its impact on Staphylococcus aureus exotoxin production.

PubMed

Qiu, Jiazhang; Li, Hongen; Su, Hongwei; Dong, Jing; Luo, Mingjing; Wang, Jianfeng; Leng, Bingfeng; Deng, Yanhong; Liu, Juxiong; Deng, Xuming

2012-04-01

In this study, fennel oil was isolated by hydrodistillation, and the chemical composition was determined by gas chromatography/mass spectral analysis. The antimicrobial activity of fennel oil against Staphylococcus aureus was evaluated by broth microdilution. A haemolysis assay, tumour necrosis factor (TNF) release assay, western blot, and real-time reverse transcription (RT)-PCR were applied to investigate the influence of fennel oil on the production of S. aureus virulence-related exoproteins. The data show that fennel oil, which contains a high level of trans-anethole, was active against S. aureus, with MICs ranging from 64 to 256 μg/ml. Furthermore, fennel oil, when used at subinhibitory concentrations, could dose-dependently decrease the expression of S. aureus exotoxins, including α-toxin, Staphylococcal enterotoxins (SEs) and toxic shock syndrome toxin 1 (TSST-1).

Biodegradation of toxic chemicals by Pleurotus eryngii in submerged fermentation and solid-state fermentation.

PubMed

Chang, Bea-Ven; Chang, Yi-Ming

2016-04-01

The toxic chemicals bisphenol A (BPA), bisphenol F (BPF), nonylphenol (NP), and tetrabromobisphenol A (TBBPA) are endocrine-disrupting chemicals that have consequently drawn much concern regarding their effect on the environment. The objectives of this study were to investigate the degradation of BPA, BPF, NP, and TBBPA by enzymes from Pleurotus eryngii in submerged fermentation (SmF) and solid-state fermentation (SSF), and also to assess the removal of toxic chemicals in spent mushroom compost (SMC). BPA and BPF were analyzed by high-performance liquid chromatography; NP and TBBPA were analyzed by gas chromatography. NP degradation was enhanced by adding CuSO4 (1 mM), MnSO4 (0.5 mM), gallic acid (1 mM), tartaric acid (20 mM), citric acid (20 mM), guaiacol (1 mM), or 2,2'-azino-bis- (3-ethylbenzothiazoline-6-sulfonic acid; 1 mM), with the last yielding a higher NP degradation rate than the other additives from SmF. The optimal conditions for enzyme activity from SSF were a sawdust/wheat bran ratio of 1:4 and a moisture content of 5 mL/g. The enzyme activities were higher with sawdust/wheat bran than with sawdust/rice bran. The optimal conditions for the extraction of enzyme from SMC required using sodium acetate buffer (pH 5.0, solid/solution ratio 1:5), and extraction over 3 hours. The removal rates of toxic chemicals by P. eryngii, in descending order of magnitude, were SSF > SmF > SMC. The removal rates were BPF > BPA > NP > TBBPA. Copyright © 2014. Published by Elsevier B.V.

[Toxicity evaluation of sewage treatment plant effluent of chemical industrial park along the Yangtze River on rat testicular germ cells in vitro].

PubMed

Hu, Guan-Jiu; Wang, Xiao-Yi; Shi, Wei; Bai, Chou-Yong; Wu, Jiang; Liu, Hong-Ling; Yu, Hong-Xia

2009-05-15

By using rat testicular germ cells in vitro toxicity testing method based on original cells culture, the reproduction toxicity of sewage treatment plant effluent of Chemical Industrial Park along the Yangtze River was evaluated, through cells changes in morphologic, activity and viability parameters. The results showed that both of the effluents from new developed Chemical Industrial Park A and provincial Chemical Industrial Park B contain reproductive toxic substances. The toxicity of Park A has more significant undergone changes in cells activity of sertoli cells (p < 0.01), spermatogenic cells (p < 0.05) and leyding cells (p < 0.05), lactate dehydrogenase activity (p < 0.01) and testosterone secretion (p < 0.01) than that of Park B. Sepermatogenic cells are more sensitive in indicating reproduction toxicity for testicular, compared with leyding cells and sertoli cells. This study demonstrated that, as an indispensable and complementary tool for water quality assessment, rat testicular germ cells in vitro toxicity testing based on original cells culture can be used to comprehensively evaluate the reproduction toxicity of sewage treatment plant effluent, and provide prompt and useful discharge quality information.

A Literature Review - Problem Definition Studies on Selected Toxic Chemicals

DTIC Science & Technology

1978-06-16

2 III. Recommendations and Hazard Analysis 6 IV. Physical and Chemical Properties 8 V. Human Toxicity A. Conditions and Extent of Exposure - 16 B...40 H. Coral 41 I. Phytoplankton and Algae 42 J. Bacteria 44 K. Plants 46 1. Fruit Trees 46 2. Foliage 49 3. Vegetables 51 4. Aquatic Plants 52 j PACE...breathe may result. The lung condition may clear up or death may occur, especially in accidents when children drink and choke on diesel fuel. The

SPATIAL VARIATION OF PM 2.5 CHEMICAL SPECIES AND SOURCE-APPORTIONED MASS CONCENTRATIONS IN NEW YORK CITY. (R827351C001)

EPA Science Inventory

Particulate matter (PM) is a chemically non-specific pollutant, and may originate or be derived from different emission source types. Thus, its toxicity may well vary depending on its chemical composition. If the PM toxicity could be determined based on source types, the regul...

Toxicity of crude oil chemically dispersed in a wave tank to embryos of Atlantic herring (Clupea harengus).

PubMed

Greer, Colleen D; Hodson, Peter V; Li, Zhengkai; King, Thomas; Lee, Kenneth

2012-06-01

Tests of crude oil toxicity to fish are often chronic, exposing embryos from fertilization to hatch to oil solutions prepared using standard mixing procedures. However, during oil spills, fish are not often exposed for long periods and the dynamic nature of the ocean is not easily replicated in the lab. Our objective was to determine if brief exposures of Atlantic herring (Clupea harengus) embryos to dispersed oil prepared by standard mixing procedures was as toxic as oil dispersed in a more realistic model system. Embryos were first exposed to chemically dispersed Alaska North Slope crude and Arabian light crude oil for 2.4 h to 14 d from fertilization to determine if exposure time affected toxicity. Toxicity increased with exposure time, but 2.4-h exposures at realistic concentrations of oil induced blue-sac disease and reduced the percentage of normal embryos at hatch; there was little difference in toxicity between the two oils. Secondly, oil was chemically dispersed in a wave tank to determine if the resultant oil solutions were as toxic to herring embryos as laboratory-derived dispersed oil using a single exposure period of 24 h. Samples taken 15 min postdispersion were more toxic than laboratory-prepared solutions, but samples taken at 5, 30, and 60 min postdispersion were less toxic. Overall, the laboratory- and wave tank-derived solutions of dispersed oil provided similar estimates of toxicity despite differences in the methods for preparing test solutions, suggesting that laboratory and wave tank data are a reliable basis for ecological risk assessments of spilled oil. Copyright © 2012 SETAC.

Species-specific predictive models of developmental toxicity using the ToxCast chemical library

EPA Science Inventory

EPA’s ToxCastTM project is profiling the in vitro bioactivity of chemicals to generate predictive models that correlate with observed in vivo toxicity. In vitro profiling methods are based on ToxCast data, consisting of over 600 high-throughput screening (HTS) and high-content sc...

Cigarette pack messages about toxic chemicals: a randomised clinical trial.

PubMed

Brewer, Noel T; Jeong, Michelle; Mendel, Jennifer R; Hall, Marissa G; Zhang, Dongyu; Parada, Humberto; Boynton, Marcella H; Noar, Seth M; Baig, Sabeeh A; Morgan, Jennifer C; Ribisl, Kurt M

2018-04-13

The USA can require tobacco companies to disclose information about harmful and potentially harmful chemicals in cigarette smoke, but the impact of these messages is uncertain. We sought to assess the effect of placing messages about toxic chemicals on smokers' cigarette packs. Participants were 719 adult cigarette smokers from California, USA, recruited from September 2016 through March 2017. We randomly assigned smokers to receive either factual messages about chemicals in cigarette smoke and their health harms (intervention) or messages about not littering cigarette butts (control) on the side of their cigarette packs for 3 weeks. The primary trial outcome was intention to quit smoking. In intent-to-treat analyses, smokers whose packs had chemical messages did not have higher intentions to quit smoking at the end of the trial than those whose packs had control messages (P=0.56). Compared with control messages, chemical messages led to higher awareness of the chemicals (28% vs 15%, P<0.001) and health harms (60% vs 52%, P=0.02) featured in the messages. In addition, chemical messages led to greater negative affect, thinking about the chemicals in cigarettes and the harms of smoking, conversations about the messages and forgoing a cigarette (all P<0.05). Chemical messages on cigarette packs did not lead to higher intentions to quit among smokers in our trial. However, chemical messages informed smokers of chemicals in cigarettes and harms of smoking, which directly supports their implementation and would be critical to defending the messages against cigarette company legal challenges. NCT02785484. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Chemical composition of wildland fire emissions

Treesearch

Shawn P. Urbanski; Wei Min Hao; Stephen Baker

2009-01-01

Wildland fires are major sources of trace gases and aerosol, and these emissions are believed to significantly influence the chemical composition of the atmosphere and the earth’s climate system. The wide variety of pollutants released by wildland fire include greenhouse gases, photochemically reactive compounds, and fine and coarse particulate matter. Through direct...

CHEMICAL STRUCTURE INDEXING OF TOXICITY DATA ON THE INTERNET: MOVING TOWARDS A FLAT WORLD

EPA Science Inventory

Standardized chemical structure annotation of public toxicity databases and information resources is playing an increasingly important role in the 'flattening' and integration of diverse sets of biological activity data on the Internet. This review discusses public initiatives th...

DISTRIBUTED STRUCTURE-SEARCHABLE TOXICITY ...

EPA Pesticide Factsheets

The ability to assess the potential genotoxicity, carcinogenicity, or other toxicity of pharmaceutical or industrial chemicals based on chemical structure information is a highly coveted and shared goal of varied academic, commercial, and government regulatory groups. These diverse interests often employ different approaches and have different criteria and use for toxicity assessments, but they share a need for unrestricted access to existing public toxicity data linked with chemical structure information. Currently, there exists no central repository of toxicity information, commercial or public, that adequately meets the data requirements for flexible analogue searching, SAR model development, or building of chemical relational databases (CRD). The Distributed Structure-Searchable Toxicity (DSSTox) Public Database Network is being proposed as a community-supported, web-based effort to address these shared needs of the SAR and toxicology communities. The DSSTox project has the following major elements: 1) to adopt and encourage the use of a common standard file format (SDF) for public toxicity databases that includes chemical structure, text and property information, and that can easily be imported into available CRD applications; 2) to implement a distributed source approach, managed by a DSSTox Central Website, that will enable decentralized, free public access to structure-toxicity data files, and that will effectively link knowledgeable toxicity data s

Biological and chemical analysis of the toxic potency of pesticides in rainwater.

PubMed

Hamers, T; Smit, M G; Murk, A J; Koeman, J H

2001-11-01

A newly developed method for measuring the integrated esterase inhibiting potency of rainwater samples was applied in practice, and the results are compared to the toxic potency calculated from concentrations of 31 organophosphate (OP) and carbamate pesticides, out of a total of 66 chemically analyzed pesticides. In addition, the general toxic potency of the rainwater samples was evaluated in a microtiter luminescence assay with Vibrio fischeri bacteria. Rainwater samples were collected over four consecutive 14-day periods in both open and wet-only samplers. The esterase inhibiting potency of the open rainwater samples (expressed as ng dichlorvos-equivalents/l) corresponded well with the chemical analyses of the rainwater samples collected by both types of samplers (r = 0.83-0.86). By far, the highest esterase inhibiting potency was found in a sample collected in an area with intense horticultural activities in June, and was attributed to high concentrations of dichlorvos, mevinphos, pirimiphos-methyl and methiocarb. The esterase inhibiting potency of this sample was equivalent to a dichlorvos concentration of 1380 ng/l in the rainwater, which is almost 2000 times higher than the maximum permissible concentration (MPC) of dichlorvos set for surface water in Netherlands. Maximum individual concentrations of dichlorvos and pirimiphos-methyl even exceeded the EC50 for Daphnia, suggesting that pesticides in rainwater pose a risk for aquatic organisms. Not all responses of the luminescence-assay for general toxicity could be explained by the analyzed pesticide concentrations. The bio-assays enable a direct assessment the toxic potency of all individual compounds present in the complex mixture of rainwater pollutants, even if they are unknown or present at concentrations below the detection limit. Therefore, they are valuable tools for prescreening and hazard characterization purposes.

Photolysis and cellular toxicities of the organic ultraviolet filter chemical octyl methoxycinnamate and its photoproducts.

PubMed

Stein, Hannah V; Berg, Courtney J; Maung, Jessica N; O'Connor, Lauren E; Pagano, Alexandra E; MacManus-Spencer, Laura A; Paulick, Margot G

2017-06-21

Organic ultraviolet filter chemicals (UVFCs) are the active ingredients used in many sunscreens to protect the skin from UV light; these chemicals have been detected in numerous aquatic environments leading to concerns about how they might affect aquatic organisms and humans. One commonly used organic UVFC is octyl methoxycinnamate (OMC), better known by its commercial name, octinoxate. Upon exposure to UV light, OMC degrades rapidly, forming numerous photoproducts, some of which have been previously identified. In this study, we isolated and completely characterized the major products of OMC photolysis, including the two major stable OMC cyclodimers. One of these cyclodimers is a δ-truxinate, resulting from a head-to-head dimerization of two OMC molecules, and the other cyclodimer is an α-truxillate, resulting from a head-to-tail dimerization of two OMC molecules. Additionally, the cellular toxicities of the individual photoproducts were determined; it was found that the parent UVFC, OMC, 4-methoxybenzaldehyde, and two cyclodimers are significantly toxic to cells. The photoproduct 2-ethylhexanol is not cytotoxic, demonstrating that different components of OMC photolysate contribute differently to its cellular toxicity. This study thus provides an enhanced understanding of OMC photolysis and gives toxicity data that can be used to better evaluate OMC as a sunscreen agent.

Global two dimensional chemistry model and simulation of atmospheric chemical composition

NASA Astrophysics Data System (ADS)

Zhang, Renjian; Wang, Mingxing; Zeng, Qingcun

2000-03-01

A global two-dimensional zonally averaged chemistry model is developed to study the chemi-cal composition of atmosphere. The region of the model is from 90°S to 90°N and from the ground to the altitude of 20 km with a resolution of 5° x 1 km. The wind field is residual circulation calcu-lated from diabatic rate. 34 species and 104 chemical and photochemical reactions are considered in the model. The sources of CH4, CO and NOx, which are divided into seasonal sources and non-seasonal sources, are parameterized as a function of latitude and time. The chemical composi-tion of atmosphere was simulated with emission level of CH4, CO and NOx in 1990. The results are compared with observations and other model results, showing that the model is successful to simu-late the atmospheric chemical composition and distribution of CH4.

Determination of the Mineral Composition and Toxic Element Contents of Propolis by Near Infrared Spectroscopy

PubMed Central

González-Martín, M. Inmaculada; Escuredo, Olga; Revilla, Isabel; Vivar-Quintana, Ana M.; Coello, M. Carmen; Palacios Riocerezo, Carlos; Wells Moncada, Guillermo

2015-01-01

The potential of near infrared spectroscopy (NIR) with remote reflectance fiber-optic probes for determining the mineral composition of propolis was evaluated. This technology allows direct measurements without prior sample treatment. Ninety one samples of propolis were collected in Chile (Bio-Bio region) and Spain (Castilla-León and Galicia regions). The minerals measured were aluminum, calcium, iron, potassium, magnesium, phosphorus, and some potentially toxic trace elements such as zinc, chromium, nickel, copper and lead. The modified partial least squares (MPLS) regression method was used to develop the NIR calibration model. The determination coefficient (R2) and root mean square error of prediction (RMSEP) obtained for aluminum (0.79, 53), calcium (0.83, 94), iron (0.69, 134) potassium (0.95, 117), magnesium (0.70, 99), phosphorus (0.94, 24) zinc (0.87, 10) chromium (0.48, 0.6) nickel (0.52, 0.7) copper (0.64, 0.9) and lead (0.70, 2) in ppm. The results demonstrated that the capacity for prediction can be considered good for wide ranges of potassium, phosphorus and zinc concentrations, and acceptable for aluminum, calcium, magnesium, iron and lead. This indicated that the NIR method is comparable to chemical methods. The method is of interest in the rapid prediction of potentially toxic elements in propolis before consumption. PMID:26540058

Dependence of Nanoparticle Toxicity on Their Physical and Chemical Properties

NASA Astrophysics Data System (ADS)

Sukhanova, Alyona; Bozrova, Svetlana; Sokolov, Pavel; Berestovoy, Mikhail; Karaulov, Alexander; Nabiev, Igor

2018-02-01

Studies on the methods of nanoparticle (NP) synthesis, analysis of their characteristics, and exploration of new fields of their applications are at the forefront of modern nanotechnology. The possibility of engineering water-soluble NPs has paved the way to their use in various basic and applied biomedical researches. At present, NPs are used in diagnosis for imaging of numerous molecular markers of genetic and autoimmune diseases, malignant tumors, and many other disorders. NPs are also used for targeted delivery of drugs to tissues and organs, with controllable parameters of drug release and accumulation. In addition, there are examples of the use of NPs as active components, e.g., photosensitizers in photodynamic therapy and in hyperthermic tumor destruction through NP incorporation and heating. However, a high toxicity of NPs for living organisms is a strong limiting factor that hinders their use in vivo. Current studies on toxic effects of NPs aimed at identifying the targets and mechanisms of their harmful effects are carried out in cell culture models; studies on the patterns of NP transport, accumulation, degradation, and elimination, in animal models. This review systematizes and summarizes available data on how the mechanisms of NP toxicity for living systems are related to their physical and chemical properties.

Exploring Chemical Routes Relevant to the Toxicity of Paracetamol and Its meta-Analogue at a Molecular Level.

PubMed

Castañeda-Arriaga, Romina; Galano, Annia

2017-06-19

Several chemical routes related to the toxicity of paracetamol (APAP, also known as acetaminophen), its analogue N-acetyl-m-aminophenol (AMAP), and their deacetylated derivatives, were investigated using the density functional theory. It was found that AMAP is more resilient to chemical oxidation than APAP. The chemical degradation of AMAP into radical intermediates is predicted to be significant only when it is induced by strong oxidants. This might explain the apparent contradictions among experimental evidence regarding AMAP toxicity. All of the investigated species are incapable of oxidizing DNA, but they can damage lipids by H atom transfer (HAT) from the bis-allylic site, with the phenoxyl radical of AMAP being the most threatening to the lipids' chemical integrity. Regarding protein damage, Cys residues were identified as the most likely targets. The damage in this case may involve two different routes: (i) HAT from the thiol site by phenoxyl radicals and (ii) protein arylation by the quinone imine (QI) derivatives. Both are not only thermochemically viable, but also are very fast reactions. According to the mechanism identified here as the most likely one for protein arylation, a rather large concentration of QI would be necessary for this damage to be significant. This might explain why APAP is nontoxic in therapeutic doses, while overdoses can result in hepatic toxicity. In addition, the QI derived from both APAP and AMAP were found to be capable of inflicting this kind of damage. In addition, it is proposed that they might increase • OH production via the Fenton reaction, which would contribute to their toxicity.

Energetic composites and method of providing chemical energy

DOEpatents

Danen, Wayne C.; Martin, Joe A.

1997-01-01

A method for providing chemical energy and energetic compositions of matter consisting of thin layers of substances which will exothermically react with one another. The layers of reactive substances are separated by thin layers of a buffer material which prevents the reactions from taking place until the desired time. The reactions are triggered by an external agent, such as mechanical stress or an electric spark. The compositions are known as metastable interstitial composites (MICs). This class of compositions includes materials which have not previously been capable of use as energetic materials. The speed and products of the reactions can be varied to suit the application.

Energetic composites and method of providing chemical energy

DOEpatents

Danen, W.C.; Martin, J.A.

1997-02-25

A method is described for providing chemical energy and energetic compositions of matter consisting of thin layers of substances which will exothermically react with one another. The layers of reactive substances are separated by thin layers of a buffer material which prevents the reactions from taking place until the desired time. The reactions are triggered by an external agent, such as mechanical stress or an electric spark. The compositions are known as metastable interstitial composites (MICs). This class of compositions includes materials which have not previously been capable of use as energetic materials. The speed and products of the reactions can be varied to suit the application. 3 figs.

Iron oxide functionalized graphene nano-composite for dispersive solid phase extraction of chemical warfare agents from aqueous samples.

PubMed

Chinthakindi, Sridhar; Purohit, Ajay; Singh, Varoon; Tak, Vijay; Goud, D Raghavender; Dubey, D K; Pardasani, Deepak

2015-05-15

Present study deals with the preparation and evaluation of graphene based magnetic nano-composite for dispersive solid phase extraction of Chemical Weapons Convention (CWC) relevant chemicals from aqueous samples. Nano-composite, Fe3O4@SiO2-G was synthesized by covalently bonding silica coated Fe3O4 onto the graphene sheets. Nerve agents (NA), Sulfur mustard (SM) and their non-toxic environmental markers were the target analytes. Extraction parameters like amount of sorbent, extraction time and desorption conditions were optimized. Dispersion of 20 milligram of sorbent in 200mL of water sample for 20min. followed by methanol/chloroform extraction produced average to good recoveries (27-94%) of targeted analytes. Recoveries of real agents exhibited great dependency upon sample pH and ionic strength. Sarin produced maximum recovery under mild acidic conditions (56% at pH 5) while VX demanded alkaline media (83% at pH 9). Salts presence in the aqueous samples was found to be advantageous, raising the recoveries to as high as 94% for SM. Excellent limits of detection (LOD) for sulphur mustard and VX (0.11ngmL(-1) and 0.19ngmL(-1) respectively) proved the utility of the developed method for the off-site analysis of CWC relevant chemicals. Copyright © 2015 Elsevier B.V. All rights reserved.

Composites Based on Polytetrafluoroethylene and Detonation Nanodiamonds: Filler-Matrix Chemical Interaction and Its Effect on a Composite's Properties

NASA Astrophysics Data System (ADS)

Koshcheev, A. P.; Perov, A. A.; Gorokhov, P. V.; Zaripov, N. V.; Tereshenkov, A. V.; Khatipov, S. A.

2018-06-01

Specific properties of PTFE composites filled with ultradisperse detonation diamonds (UDDs) with different surface chemistries are studied. It is found for the first time that filler in the form of UDDs affects not only the rate of PTFE thermal decomposition in vacuum pyrolysis, but also the chemical composition of the products of degradation. The wear resistance of UDD/PTFE composites is shown to depend strongly on the UDD surface chemistry. The presence of UDDs in a PTFE composite is found to result in perfluorocarbon telomeres, released as a readily condensable fraction upon composite pyrolysis. The chemical interaction between PTFE and UDDs, characterized by an increase in the rate of gas evolution and a change in the desorbed gas's composition, is found to occur at temperature as low as 380°C. It is shown that the intensity of this interaction depends on the concentration of oxygen-containing surface groups, the efficiency of UDDs in terms of the composite's wear resistance being reduced due to the presence of these groups. Based on the experimental data, a conclusion is reached about the chemical interaction between UDDs and a PTFE matrix, its dependence on the nanodiamond surface chemistry, and its effect on a composite's tribology.

ToxiFly: Can Fruit Flies be Used to Identify Toxicity Pathways for Airborne Chemicals?

EPA Science Inventory

Current high-throughput and alternative screening assays for chemical toxicity are unable to test volatile organic compounds (VOCs), thus limiting their scope. Further, the data generated by these assays require mechanistic information to link effects at molecular targets to adve...

A mixture toxicity approach to predict the toxicity of Ag decorated ZnO nanomaterials.

PubMed

Azevedo, S L; Holz, T; Rodrigues, J; Monteiro, T; Costa, F M; Soares, A M V M; Loureiro, S

2017-02-01

Nanotechnology is a rising field and nanomaterials can now be found in a vast variety of products with different chemical compositions, sizes and shapes. New nanostructures combining different nanomaterials are being developed due to their enhancing characteristics when compared to nanomaterials alone. In the present study, the toxicity of a nanostructure composed by a ZnO nanomaterial with Ag nanomaterials on its surface (designated as ZnO/Ag nanostructure) was assessed using the model-organism Daphnia magna and its toxicity predicted based on the toxicity of the single components (Zn and Ag). For that ZnO and Ag nanomaterials as single components, along with its mixture prepared in the laboratory, were compared in terms of toxicity to ZnO/Ag nanostructures. Toxicity was assessed by immobilization and reproduction tests. A mixture toxicity approach was carried out using as starting point the conceptual model of Concentration Addition. The laboratory mixture of both nanomaterials showed that toxicity was dependent on the doses of ZnO and Ag used (immobilization) or presented a synergistic pattern (reproduction). The ZnO/Ag nanostructure toxicity prediction, based on the percentage of individual components, showed an increase in toxicity when compared to the expected (immobilization) and dependent on the concentration used (reproduction). This study demonstrates that the toxicity of the prepared mixture of ZnO and Ag and of the ZnO/Ag nanostructure cannot be predicted based on the toxicity of their components, highlighting the importance of taking into account the interaction between nanomaterials when assessing hazard and risk. Copyright © 2016 Elsevier B.V. All rights reserved.

Chemical composition studies of flint with different origins

NASA Astrophysics Data System (ADS)

Zarina, Liga; Seglins, Valdis; Kostjukovs, Juris; Burlakovs, Juris

2015-04-01

Flint is a widely used material in the Stone Age because of its physical characteristics, which makes the material suitable for obtaining tools with sharp working edges. Chert, flint, chalcedony, agate and jasper in composition and several other physical characteristics are very similar. Therefore in archaeology most often they are determined simplified and are not distinguished, but described as flint or chert, denoting only the material in a general sense. However, in-depth studies it is necessary accurately identify the rock type and, in addition, to determine the origin of the flint and the conditions of the formation for the various archaeological research needs. As a typical example can be noted the localization problems in determining whether flint is local, or have emerged in the region through the exchange or by transportation. Flint consists mainly from quartz and mostly it has cryptocrystalline or amorphous structure. In nature it occurs as nodules and interbedded inclusions in sedimentary deposits as a result of digenesis processes when calcium carbonate is replaced with silicia. Bedded chert primarily is accumulations originated from excess alkalinity in the sediments. Flint can also be formed in the crystallization processes of the chemically unstable amorphous silicia. In this context, it should be noted that flint is naturally heterogeneous and very varied material by the physical properties and therefore problematic in many contemporary studies. In the study different origin flint samples from England, Denmark and Latvia were compared after their chemical composition. Flint nodules from Northern Europe chalk cliffs formed as inclusions in interbedded deposits or results of the digenesis and samples of chalcedony saturated dolomite from Latvia formed in hydrothermal processes were analysed using XRD and XRF methods. The obtained data were statistically analysed, identifying major, minor and trace elements and subsequently assessing the chemical

Low molecular weight chemicals, hypersensitivity, and direct toxicity: the acid anhydrides.

PubMed Central

Venables, K M

1989-01-01

The acid anhydrides are a group of reactive chemicals used widely in alkyd and epoxy resins. The major hazards to health are mucosal and skin irritation and sensitisation of the respiratory tract. Most occupational asthma caused by acid anhydrides appears to be immunologically mediated. Immunological mechanisms have been proposed to explain an influenza-like syndrome and pulmonary haemorrhage, but direct toxicity may also be important in the aetiology of these conditions. PMID:2653411

Classification and prediction of toxicity of chemicals using an automated phenotypic profiling of Caenorhabditis elegans.

PubMed

Gao, Shan; Chen, Weiyang; Zeng, Yingxin; Jing, Haiming; Zhang, Nan; Flavel, Matthew; Jois, Markandeya; Han, Jing-Dong J; Xian, Bo; Li, Guojun

2018-04-18

Traditional toxicological studies have relied heavily on various animal models to understand the effect of various compounds in a biological context. Considering the great cost, complexity and time involved in experiments using higher order organisms. Researchers have been exploring alternative models that avoid these disadvantages. One example of such a model is the nematode Caenorhabditis elegans. There are some advantages of C. elegans, such as small size, short life cycle, well defined genome, ease of maintenance and efficient reproduction. As these benefits allow large scale studies to be initiated with relative ease, the problem of how to efficiently capture, organize and analyze the resulting large volumes of data must be addressed. We have developed a new method for quantitative screening of chemicals using C. elegans. 33 features were identified for each chemical treatment. The compounds with different toxicities were shown to alter the phenotypes of C. elegans in distinct and detectable patterns. We found that phenotypic profiling revealed conserved functions to classify and predict the toxicity of different chemicals. Our results demonstrate the power of phenotypic profiling in C. elegans under different chemical environments.

High Throughput Prioritization for Integrated Toxicity Testing Based on ToxCast Chemical Profiling

EPA Science Inventory

The rational prioritization of chemicals for integrated toxicity testing is a central goal of the U.S. EPA’s ToxCast™ program (http://epa.gov/ncct/toxcast/). ToxCast includes a wide-ranging battery of over 500 in vitro high-throughput screening assays which in Phase I was used to...

A combined approach to investigate the toxicity of an industrial landfill's leachate: Chemical analyses, risk assessment and in vitro assays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baderna, D., E-mail: diego.baderna@marionegri.it; Maggioni, S.; Boriani, E.

2011-05-15

Solid wastes constitute an important and emerging problem. Landfills are still one of the most common ways to manage waste disposal. The risk assessment of pollutants from landfills is becoming a major environmental issue in Europe, due to the large number of sites and to the importance of groundwater protection. Furthermore, there is lack of knowledge for the environmental, ecotoxicological and toxicological characteristics of most contaminants contained into landfill leacheates. Understanding leachate composition and creating an integrated strategy for risk assessment are currently needed to correctly face the landfill issues and to make projections on the long-term impacts of amore » landfill, with particular attention to the estimation of possible adverse effects on human health and ecosystem. In the present study, we propose an integrated strategy to evaluate the toxicity of the leachate using chemical analyses, risk assessment guidelines and in vitro assays using the hepatoma HepG2 cells as a model. The approach was applied on a real case study: an industrial waste landfill in northern Italy for which data on the presence of leachate contaminants are available from the last 11 years. Results from our ecological risk models suggest important toxic effects on freshwater fish and small rodents, mainly due to ammonia and inorganic constituents. Our results from in vitro data show an inhibition of cell proliferation by leachate at low doses and cytotoxic effect at high doses after 48 h of exposure. - Research highlights: {yields} We study the toxicity of leachate from a non-hazardous industrial waste landfill. {yields} We perform chemical analyses, risk assessments and in vitro assays on HepG2 cells. {yields} Risk models suggest toxic effects due to ammonia and inorganic constituents. {yields} In vitro assays show that leachate inhibits cell proliferation at low doses. {yields} Leachate can induce cytotoxic effects on HepG2 cells at high doses.« less

Comparison of the toxicities, activities and chemical profiles of raw and processed Xanthii Fructus.

PubMed

Su, Tao; Cheng, Brian Chi-Yan; Fu, Xiu-Qiong; Li, Ting; Guo, Hui; Cao, Hui-Hui; Kwan, Hiu-Yee; Tse, Anfernee Kai-Wing; Yu, Hua; Cao, Hui; Yu, Zhi-Ling

2016-01-22

Although toxic, the Chinese medicinal herb Xanthii Fructus (XF) is commonly used to treat traditional Chinese medicine (TCM) symptoms that resemble cold, sinusitis and arthritis. According to TCM theory, stir-baking (a processing method) can reduce the toxicity and enhance the efficacy of XF. Cytotoxicities of raw XF and processed XF (stir-baked XF, SBXF) were determined by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay in normal liver derived MIHA cells. Nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) mRNA expression were measured by the Griess reagent and quantitative real-time PCR, respectively. The chemical profiles of XF and SBXF were compared using an established ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/Q-TOF-MS) method. SBXF was less toxic than XF in MIHA cells. Both XF and SBXF had anti-inflammatory effects as demonstrated by their abilities to reduce nitric oxide production as well as inducible nitric oxide synthase mRNA expression in lipopolysaccharide-stimulated RAW 264.7 macrophages. Interestingly, the anti-inflammatory effects of SBXF were more potent than that of XF. By comparing the chemical profiles, we found that seven peaks were lower, while nine other peaks were higher in SBXF than in XF. Eleven compounds including carboxyatractyloside, atractyloside and chlorogenic acid corresponding to eleven individual changed peaks were tentatively identified by matching with empirical molecular formulae and mass fragments, as well as literature data. Our study showed that stir-baking significantly reduced the cytotoxicity and enhanced the anti-inflammatory effects of XF; moreover, with a developed ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry method we differentiated XF and SBXF by their chemical profiles. Further studies are warranted to establish the relationship between the alteration of chemical profiles and the

Chemical characterization and toxicity of particulate matter emissions from roadside trash combustion in urban India

NASA Astrophysics Data System (ADS)

Vreeland, Heidi; Schauer, James J.; Russell, Armistead G.; Marshall, Julian D.; Fushimi, Akihiro; Jain, Grishma; Sethuraman, Karthik; Verma, Vishal; Tripathi, Sachi N.; Bergin, Michael H.

2016-12-01

Roadside trash burning is largely unexamined as a factor that influences air quality, radiative forcing, and human health even though it is ubiquitously practiced across many global regions, including throughout India. The objective of this research is to examine characteristics and redox activity of fine particulate matter (PM2.5) associated with roadside trash burning in Bangalore, India. Emissions from smoldering and flaming roadside trash piles (n = 24) were analyzed for organic and elemental carbon (OC/EC), brown carbon (BrC), and toxicity (i.e. redox activity, measured via the dithiothreitol "DTT" assay). A subset of samples (n = 8) were further assessed for toxicity by a cellular assay (macrophage assay) and also analyzed for trace organic compounds. Results show high variability of chemical composition and toxicity between trash-burning emissions, and characteristic differences from ambient samples. OC/EC ratios for trash-burning emissions range from 0.8 to 1500, while ambient OC/EC ratios were observed at 5.4 ± 1.8. Trace organic compound analyses indicate that emissions from trash-burning piles were frequently composed of aromatic di-acids (likely from burning plastics) and levoglucosan (an indicator of biomass burning), while the ambient sample showed high response from alkanes indicating notable representation from vehicular exhaust. Volume-normalized DTT results (i.e., redox activity normalized by the volume of air pulled through the filter during sampling) were, unsurprisingly, extremely elevated in all trash-burning samples. Interestingly, DTT results suggest that on a per-mass basis, fresh trash-burning emissions are an order of magnitude less redox-active than ambient air (13.4 ± 14.8 pmol/min/μgOC for trash burning; 107 ± 25 pmol/min/μgOC for ambient). However, overall results indicate that near trash-burning sources, exposure to redox-active PM can be extremely high.

Chemical characterisation of Piper amalago (Piperaceae) essential oil by comprehensive two-dimensional gas chromatography coupled with rapid-scanning quadrupole mass spectrometry (GC×GC/qMS) and their antilithiasic activity and acute toxicity.

PubMed

Dos Santos, Anaí L; Novaes, Antônio da Silva; Polidoro, Allan Dos S; de Barros, Márcio Eduardo; Mota, Jonas S; Lima, Daiane B M; Krause, Laiza C; Cardoso, Cláudia A L; Jacques, Rosângela A; Caramão, Elina B

2018-02-26

Piper amalago has a distribution from Mexico to Brazil; their aerial parts have been used in folk medicine to treat diuretic and kidney diseases. The purpose of this study was to obtain a deeper understanding of the chemical composition of essential oils (EOs) extracted from both the leaves and stems of P. amalago, compare them, and evaluate their antilithiasic activity and acute toxicity. Extraction was performed by hydrodistillation, whereas chemical characterisation by two-dimensional gas chromatography coupled with rapid-scanning quadrupole mass spectrometry (GC×GC/qMS). The antilithiasic activity was evaluated by the effect of the EOs on calcium oxalate crystallisation in vitro. The turbidity index and the number of crystals formed were determined and used as an estimative of the activity. In the acute toxicity assay, the effects of a single oral dose of the EOs in Wistar rats were determined. General behaviour, adverse effects, and mortality were determined. A total of 322 compounds were identified in the EOs. The sesquiterpenes displayed the highest contribution in leaves EOs among which included bicyclogermacrene and δ-cadinene. Sesquiterpenes and oxygenated sesquiterpenes displayed the highest contribution in EOs from stems, among which included bicyclogermacrene and α-cadinol. The EOs demonstrated an excellent action on the crystals growth inhibition, and the oral dose tested did not induce significant changes in the parameters for acute toxicity. The oils have a high chemical complexity, and there are differences between their compositions, which could explain the observed differences in antilithiasic activity. The findings support the use of this plant in folk medicine to treat kidney diseases. Copyright © 2018 John Wiley & Sons, Ltd.

2006 Toxic Chemical Release Inventory Report for the Emergency Planning and Community Right-to-Know Act of 1986, Title III, Section 313

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ecology and Air Quality Group

2007-12-12

For reporting year 2006, Los Alamos National Laboratory (LANL or the Laboratory) submitted Form R reports for lead as required under the Emergency Planning and Community Right-to-Know Act (EPCRA) Section 313. No other EPCRA Section 313 chemicals were used in 2006 above the reportable thresholds. This document was prepared to provide a description of the evaluation of EPCRA Section 313 chemical use and threshold determinations for LANL for calendar year 2006, as well as to provide background information about data included on the Form R reports. Section 313 of EPCRA specifically requires facilities to submit a Toxic Chemical Release Inventorymore » Report (Form R) to the U.S. Environmental Protection Agency (EPA) and state agencies if the owners and operators manufacture, process, or otherwise use any of the listed toxic chemicals above listed threshold quantities. EPA compiles this data in the Toxic Release Inventory database. Form R reports for each chemical over threshold quantities must be submitted on or before July 1 each year and must cover activities that occurred at the facility during the previous year. In 1999, EPA promulgated a final rule on persistent bioaccumulative toxics (PBTs). This rule added several chemicals to the EPCRA Section 313 list of toxic chemicals and established lower reporting thresholds for these and other PBT chemicals that were already reportable. These lower thresholds became applicable in reporting year 2000. In 2001, EPA expanded the PBT rule to include a lower reporting threshold for lead and lead compounds. Facilities that manufacture, process, or otherwise use more than 100 lb of lead or lead compounds must submit a Form R.« less

Chemical Composition of Rainwater in Córdoba City, Argentina

NASA Astrophysics Data System (ADS)

López, M. L.; Asar, M. L.; Ceppi, S.; Bürgesser, R. E.; Avila, E.

2013-05-01

Sampling and chemical analysis of rainwater has proved to be a useful technique for studying its chemical composition and provides a greater understanding of local and regional dispersion of pollutants and their potential impacts to ecosystems through deposition processes. Samples of rainwater were collected during 2009-2012, in Córdoba city, Argentina. Two kind of sampling were performed: event-specific and sequential. The objective of the first of these was to determine the chemical concentration of the total rain, while the objective of the second one was to analyze the variability of the chemical concentration during an individual rain event. The total volume of each sample was divided in halves. One half was filtered through 0.45 μm membrane filter. After this, all the samples were reduced by evaporation to a final volume of 10 ml. The non-filtered samples were acidified and digested in accordance to the method 3050B of the Environmental Protection Agency (EPA) for acid digestion of sediments. Multi-elemental standard solutions in different concentrations were prepared by adequate dilutions. Gallium was added as an internal standard in all standard solutions and samples. Exactly 5 μL of these solutions were deposited on acrylic supports. When these droplets were dried, Synchrotron Radiation Total Reflection X-Ray Fluorescence technique was used for determining the chemical elements. Spectra were analyzed with the AXIL package for spectrum analysis. Due to the intrinsic characteristics of the total reflection technique, the background of the measurements is significantly reduced and there are no matrix effects, therefore quantification can be obtained from the linear correlation between fluorescence intensity and the concentration of the element of interest. The elements quantified were S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, and Pb. For all of them a calibration curve was performed in order to quantify their concentrations on the

Environmental Pollution, Toxicity Profile and Treatment Approaches for Tannery Wastewater and Its Chemical Pollutants.

PubMed

Saxena, Gaurav; Chandra, Ram; Bharagava, Ram Naresh

Leather industries are key contributors in the economy of many developing countries, but unfortunately they are facing serious challenges from the public and governments due to the associated environmental pollution. There is a public outcry against the industry due to the discharge of potentially toxic wastewater having alkaline pH, dark brown colour, unpleasant odour, high biological and chemical oxygen demand, total dissolved solids and a mixture of organic and inorganic pollutants. Various environment protection agencies have prioritized several chemicals as hazardous and restricted their use in leather processing however; many of these chemicals are used and discharged in wastewater. Therefore, it is imperative to adequately treat/detoxify the tannery wastewater for environmental safety. This paper provides a detail review on the environmental pollution and toxicity profile of tannery wastewater and chemicals. Furthermore, the status and advances in the existing treatment approaches used for the treatment and/or detoxification of tannery wastewater at both laboratory and pilot/industrial scale have been reviewed. In addition, the emerging treatment approaches alone or in combination with biological treatment approaches have also been considered. Moreover, the limitations of existing and emerging treatment approaches have been summarized and potential areas for further investigations have been discussed. In addition, the clean technologies for waste minimization, control and management are also discussed. Finally, the international legislation scenario on discharge limits for tannery wastewater and chemicals has also been discussed country wise with discharge standards for pollution prevention due to tannery wastewater.

The U.S. EPA's ToxCast Chemical Screening Program and Predictive Modeling of Toxicity

EPA Science Inventory

The ToxCast program was developed by the U.S. EPA's National Center for Computational Toxicology to provide cost-effective high-throughput screening for the potential toxicity of thousands of chemicals. Phase I screened 309 compounds in over 500 assays to evaluate concentration-...

Relationships between aquatic toxicity, chemical hydrophobicity and mode of action: log kow QSARs revisited

EPA Science Inventory

Relationships between chemical hydrophobicity and toxicity have been shown for nearly 100 years in both mammals and fish, typically using the log of the octanol:water partition coefficient (kow). The current study reassessed the influence of mode of action (MOA) on aquatic toxici...

Assessing contaminant sensitivity of endangered and threatened aquatic species: Part I. Acute toxicity of five chemicals

USGS Publications Warehouse

Dwyer, F.J.; Mayer, F.L.; Sappington, L.C.; Buckler, D.R.; Bridges, C.M.; Greer, I.E.; Hardesty, D.K.; Henke, C.E.; Ingersoll, C.G.; Kunz, J.L.; Whites, D.W.; Augspurger, T.; Mount, D.R.; Hattala, K.; Neuderfer, G.N.

2005-01-01

Assessment of contaminant impacts to federally identified endangered, threatened and candidate, and state-identified endangered species (collectively referred to as "listed" species) requires understanding of a species' sensitivities to particular chemicals. The most direct approach would be to determine the sensitivity of a listed species to a particular contaminant or perturbation. An indirect approach for aquatic species would be application of toxicity data obtained from standard test procedures and species commonly used in laboratory toxicity tests. Common test species (fathead minnow, Pimephales promelas; sheepshead minnow, Cyprinodon variegatus; and rainbow trout, Oncorhynchus mykiss) and 17 listed or closely related species were tested in acute 96-hour water exposures with five chemicals (carbaryl, copper, 4-nonylphenol, pentachlorophenol, and permethrin) representing a broad range of toxic modes of action. No single species was the most sensitive to all chemicals. For the three standard test species evaluated, the rainbow trout was more sensitive than either the fathead minnow or sheepshead minnow and was equal to or more sensitive than listed and related species 81% of the time. To estimate an LC50 for a listed species, a factor of 0.63 can be applied to the geometric mean LC50 of rainbow trout toxicity data, and more conservative factors can be determined using variance estimates (0.46 based on 1 SD of the mean and 0.33 based on 2 SD of the mean). Additionally, a low- or no-acute effect concentration can be estimated by multiplying the respective LC50 by a factor of approximately 0.56, which supports the United States Environmental Protection Agency approach of multiplying the final acute value by 0.5 (division by 2). When captive or locally abundant populations of listed fish are available, consideration should be given to direct testing. When direct toxicity testing cannot be performed, approaches for developing protective measures using common test

Toxicity testing of restorative dental materials using brine shrimp larvae (Artemia salina).

PubMed

Milhem, Manar M; Al-Hiyasat, Ahmad S; Darmani, Homa

2008-01-01

This study investigated the effect of extracts of different composites, glass ionomer cement (GIC)s and compomers on the viability of brine shrimp larvae. Ethanolic extracts of four dental composites (Z-100; Solitaire 2; Filtek P60 and Synergy), a conventional GIC (Ketac-Fil), a resin-modified glass ionomer cement (Vitremer), two compomers (F2000; Dyract AP), and a flowable compomer (Dyract Flow) were prepared from each material. Following evaporation of the ethanol, the extracts were resuspended in distilled water, which was then used to test the effects on the viability of brine shrimp larvae. For the composites, the extract of Synergy was the least toxic (88% viability) followed by the extracts of Solitaire 2, Z100 and P60 (75%, 67.5% and 50% viability, respectively). One-way ANOVA revealed highly significant differences between the resin composite materials (p<0.001). Follow-up comparison between the composite groups by Tukey's pairwise multiple-comparison test (alpha =0.05) showed that the extract of Synergy was significantly less toxic than the extracts of all the other materials except that of Solitaire 2. The compomers showed 100% lethality, while the percentage of viable larvae for the extracts of Ketac-Fil, and Vitremer were 32.3%, and 37.0%, respectively. One-way ANOVA revealed highly significant differences between the groups of materials (p<0.001). Follow-up comparison between the groups by Tukey's test (alpha = 0.05) showed that the toxic effect of the extracts of the compomers were significantly greater than that of Ketac-Fil, and Vitremer. The differences in the toxic effects of Vitremer and Ketac-Fil were not statistically significant. In conclusion, the toxicity of composite materials varied according to their chemical composition. Compomers were the most lethal materials to brine shrimp larvae followed by GICs and then composites.

TOXICITY TESTING OF RESTORATIVE DENTAL MATERIALS USING BRINE SHRIMP LARVAE (ARTEMIA SALINA)

PubMed Central

Milhem, Manar M.; Al-Hiyasat, Ahmad S.; Darmani, Homa

2008-01-01

This study investigated the effect of extracts of different composites, glass ionomer cement (GIC)s and compomers on the viability of brine shrimp larvae. Ethanolic extracts of four dental composites (Z-100; Solitaire 2; Filtek P60 and Synergy), a conventional GIC (Ketac-Fil), a resin-modified glass ionomer cement (Vitremer), two compomers (F2000; Dyract AP), and a flowable compomer (Dyract Flow) were prepared from each material. Following evaporation of the ethanol, the extracts were resuspended in distilled water, which was then used to test the effects on the viability of brine shrimp larvae. For the composites, the extract of Synergy was the least toxic (88% viability) followed by the extracts of Solitaire 2, Z100 and P60 (75%, 67.5% and 50% viability, respectively). One-way ANOVA revealed highly significant differences between the resin composite materials (p<0.001). Follow-up comparison between the composite groups by Tukey's pairwise multiple-comparison test (α =0.05) showed that the extract of Synergy was significantly less toxic than the extracts of all the other materials except that of Solitaire 2. The compomers showed 100% lethality, while the percentage of viable larvae for the extracts of Ketac-Fil, and Vitremer were 32.3%, and 37.0%, respectively. One-way ANOVA revealed highly significant differences between the groups of materials (p<0.001). Follow-up comparison between the groups by Tukey's test (α = 0.05) showed that the toxic effect of the extracts of the compomers were significantly greater than that of Ketac-Fil, and Vitremer. The differences in the toxic effects of Vitremer and Ketac-Fil were not statistically significant. In conclusion, the toxicity of composite materials varied according to their chemical composition. Compomers were the most lethal materials to brine shrimp larvae followed by GICs and then composites. PMID:19089264

A COMPARISON OF THE LETHAL AND SUBLETHAL TOXICITY OF ORGANIC CHEMICAL MIXTURES TO THE FATHEAD MINNOW (PIMEPHALES PROMELAS)

EPA Science Inventory

The joint toxic effects of known binary and multiple organic chemical mixtures to the fathead minnow (Pimephales promelas) were defined at both the 96-h 50% lethal effect concentration (LC50) and sublethal (32-d growth) response levels for toxicants with a narcosis I, narcosis II...

ADMET Evaluation in Drug Discovery. 18. Reliable Prediction of Chemical-Induced Urinary Tract Toxicity by Boosting Machine Learning Approaches.

PubMed

Lei, Tailong; Sun, Huiyong; Kang, Yu; Zhu, Feng; Liu, Hui; Zhou, Wenfang; Wang, Zhe; Li, Dan; Li, Youyong; Hou, Tingjun

2017-11-06

Xenobiotic chemicals and their metabolites are mainly excreted out of our bodies by the urinary tract through the urine. Chemical-induced urinary tract toxicity is one of the main reasons that cause failure during drug development, and it is a common adverse event for medications, natural supplements, and environmental chemicals. Despite its importance, there are only a few in silico models for assessing urinary tract toxicity for a large number of compounds with diverse chemical structures. Here, we developed a series of qualitative and quantitative structure-activity relationship (QSAR) models for predicting urinary tract toxicity. In our study, the recursive feature elimination method incorporated with random forests (RFE-RF) was used for dimension reduction, and then eight machine learning approaches were used for QSAR modeling, i.e., relevance vector machine (RVM), support vector machine (SVM), regularized random forest (RRF), C5.0 trees, eXtreme gradient boosting (XGBoost), AdaBoost.M1, SVM boosting (SVMBoost), and RVM boosting (RVMBoost). For building classification models, the synthetic minority oversampling technique was used to handle the imbalance data set problem. Among all the machine learning approaches, SVMBoost based on the RBF kernel achieves both the best quantitative (q ext 2 = 0.845) and qualitative predictions for the test set (MCC of 0.787, AUC of 0.893, sensitivity of 89.6%, specificity of 94.1%, and global accuracy of 90.8%). The application domains were then analyzed, and all of the tested chemicals fall within the application domain coverage. We also examined the structure features of the chemicals with large prediction errors. In brief, both the regression and classification models developed by the SVMBoost approach have reliable prediction capability for assessing chemical-induced urinary tract toxicity.

Assessment of quantitative structure-activity relationship of toxicity prediction models for Korean chemical substance control legislation

PubMed Central

Kim, Kwang-Yon; Shin, Seong Eun; No, Kyoung Tai

2015-01-01

Objectives For successful adoption of legislation controlling registration and assessment of chemical substances, it is important to obtain sufficient toxicological experimental evidence and other related information. It is also essential to obtain a sufficient number of predicted risk and toxicity results. Particularly, methods used in predicting toxicities of chemical substances during acquisition of required data, ultimately become an economic method for future dealings with new substances. Although the need for such methods is gradually increasing, the-required information about reliability and applicability range has not been systematically provided. Methods There are various representative environmental and human toxicity models based on quantitative structure-activity relationships (QSAR). Here, we secured the 10 representative QSAR-based prediction models and its information that can make predictions about substances that are expected to be regulated. We used models that predict and confirm usability of the information expected to be collected and submitted according to the legislation. After collecting and evaluating each predictive model and relevant data, we prepared methods quantifying the scientific validity and reliability, which are essential conditions for using predictive models. Results We calculated predicted values for the models. Furthermore, we deduced and compared adequacies of the models using the Alternative non-testing method assessed for Registration, Evaluation, Authorization, and Restriction of Chemicals Substances scoring system, and deduced the applicability domains for each model. Additionally, we calculated and compared inclusion rates of substances expected to be regulated, to confirm the applicability. Conclusions We evaluated and compared the data, adequacy, and applicability of our selected QSAR-based toxicity prediction models, and included them in a database. Based on this data, we aimed to construct a system that can be used

Studies on thermo-mechanical properties of chemically treated jute-polyester composite

NASA Astrophysics Data System (ADS)

Chaudhari, Vikas; Chandekar, Harichandra; Saboo, Jayesh; Mascarenhas, Adlete

2018-03-01

The effect of chemical treatments on jute-polyester composites is studied in this paper. The jute fabrics are chemically treated with NaOH and benzoyl chloride and its tensile and visco-elastic properties are compared with untreated jute composite. The NaOH treated jute-polyester composite show superior tensile strength and modulus compared to other jute-polyester composites. The glass transition temperature obtained from DMA shift to higher temperature for composites in comparison to polyester resin, this is due to restriction of mobility in chains due to introduction of jute reinforcement. The DMA results also show favourable results towards NaOH treatment i.e. higher storage modulus and lower tan δ values relative to untreated jute-polyester composite. The benzoyl treated jute-polyester composite however do not show promising results which may be attributed to the fact that the adhesion properties associated with similar ester functional groups in the benzoyl treated jute fabric and polyester resin were not obtained.

Toxicity of ferric chloride sludge to aquatic organisms.

PubMed

Sotero-Santos, Rosana B; Rocha, Odete; Povinelli, Jurandyr

2007-06-01

Iron-rich sludge from a drinking water treatment plant (DWTP) was investigated regarding its toxicity to aquatic organisms and physical and chemical composition. In addition, the water quality of the receiving stream near the DWTP was evaluated. Experiments were carried out in August 1998, February 1999 and May 1999. Acute toxicity tests were carried out on a cladoceran (Daphnia similis), a midge (Chironomus xanthus) and a fish (Hyphessobrycon eques). Chronic tests were conducted only on D. similis. Acute sludge toxicity was not detected using any of the aquatic organisms, but chronic effects were observed upon the fecundity of D. similis. Although there were relatively few sample dates, the results suggested that the DWTP sludge had a negative effect on the receiving body as here was increased suspended matter, turbidity, conductivity, chemical oxygen demand (COD) and hardness in the water downstream of the DWTP effluent discharge. The ferric chloride sludge also exhibited high heavy metal concentrations revealing a further potential for pollution and harmful chronic effects on the aquatic biota when the sludge is disposed of without previous treatment.

Probing nanomechanical interaction at the interface between biological membrane and potentially toxic chemical.

PubMed

Lim, Chanoong; Park, Sohee; Park, Jinwoo; Ko, Jina; Lee, Dong Woog; Hwang, Dong Soo

2018-04-12

Various xenobiotics interact with biological membranes, and precise evaluations of the molecular interactions between them are essential to foresee the toxicity and bioavailability of existing or newly synthesized molecules. In this study, surface forces apparatus (SFA) measurement and Langmuir trough based tensiometry are performed to reveal nanomechanical interaction mechanisms between potential toxicants and biological membranes for ex vivo toxicity evaluation. As a toxicant, polyhexamethylene guanidine (PHMG) was selected because PHMG containing humidifier disinfectant and Vodka caused lots of victims in both S. Korea and Russia, respectively, due to the lack of holistic toxicity evaluation of PHMG. Here, we measured strong attraction (Wad ∼4.2 mJ/m 2 ) between PHMG and head group of biological membranes while no detectable adhesion force between the head group and control molecules was measured. Moreover, significant changes in π-A isotherm of 1,2-Dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) monolayers were measured upon PHMG adsorption. These results indicate PHMG strongly binds to hydrophilic group of lipid membranes and alters the structural and phase behavior of them. More importantly, complementary utilization of SFA and Langmuir trough techniques are found to be useful to predict the potential toxicity of a chemical by evaluating the molecular interaction with biological membranes, the primary protective barrier for living organisms. Copyright © 2018 Elsevier B.V. All rights reserved.

Transferring mixtures of chemicals from sediment to a bioassay using silicone-based passive sampling and dosing.

PubMed

Mustajärvi, Lukas; Eriksson-Wiklund, Ann-Kristin; Gorokhova, Elena; Jahnke, Annika; Sobek, Anna

2017-11-15

Environmental mixtures of chemicals consist of a countless number of compounds with unknown identity and quantity. Yet, chemical regulation is mainly built around the assessment of single chemicals. Existing frameworks for assessing the toxicity of mixtures require that both the chemical composition and quantity are known. Quantitative analyses of the chemical composition of environmental mixtures are however extremely challenging and resource-demanding. Bioassays may therefore serve as a useful approach for investigating the combined toxicity of environmental mixtures of chemicals in a cost-efficient and holistic manner. In this study, an unknown environmental mixture of bioavailable semi-hydrophobic to hydrophobic chemicals was sampled from a contaminated sediment in a coastal Baltic Sea area using silicone polydimethylsiloxane (PDMS) as an equilibrium passive sampler. The chemical mixture was transferred to a PDMS-based passive dosing system, and its applicability was demonstrated using green algae Tetraselmis suecica in a cell viability assay. The proportion of dead cells increased significantly with increasing exposure level and in a dose-response manner. At an ambient concentration, the proportion of dead cells in the population was nearly doubled compared to the control; however, the difference was non-significant due to high inter-replicate variability and a low number of replicates. The validation of the test system regarding equilibrium sampling, loading efficiency into the passive dosing polymer, stability of the mixture composition, and low algal mortality in control treatments demonstrates that combining equilibrium passive sampling and passive dosing is a promising tool for investigating the toxicity of bioavailable semi-hydrophobic and hydrophobic chemicals in complex environmental mixtures.

Chemical Composition Measurements of LAWA44 Glass Samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fox, K.; Edwards, T.; Riley, W.

2016-11-15

DOE is building the Hanford Tank Waste Treatment and Immobilization Plant (WTP) at the Hanford Site in Washington to remediate 55 million gallons of radioactive waste that is temporarily stored in 177 underground tanks. Both low-activity and high-level wastes will then be vitrified into borosilicate glass using Joule-heated ceramic melters. Efforts are being made to increase the loading of Hanford tank wastes in the glass. One area of work is enhancing waste glass composition/property models and broadening the compositional regions over which those models are applicable. In this report, the Savannah River National Laboratory provides chemical analysis results for severalmore » samples of a simulated low-activity waste glass, LAWA44, provided by the Pacific Northwest National Laboratory as part of an ongoing development task. The measured chemical composition data are reported and compared with the targeted values for each component for each glass. A detailed review showed no indications of errors in the preparation or measurement of the study glasses. All of the measured sums of oxides for the study glasses fell within the interval of 97.9 to 102.6 wt %, indicating acceptable recovery of the glass components. Comparisons of the targeted and measured chemical compositions showed that the measured values for the glasses met the targeted concentrations within 10% for those components present at more than 5 wt %. It was noted that the measured B 2O 3 concentrations are somewhat above the targeted values for the study glasses. No obvious trends were observed with regard to the multiple melting steps used to prepare the study glasses, indicating that any potential effects of volatility were below measurable thresholds.« less

Development of a general baseline toxicity QSAR model for the fish embryo acute toxicity test.

PubMed

Klüver, Nils; Vogs, Carolina; Altenburger, Rolf; Escher, Beate I; Scholz, Stefan

2016-12-01

Fish embryos have become a popular model in ecotoxicology and toxicology. The fish embryo acute toxicity test (FET) with the zebrafish embryo was recently adopted by the OECD as technical guideline TG 236 and a large database of concentrations causing 50% lethality (LC 50 ) is available in the literature. Quantitative Structure-Activity Relationships (QSARs) of baseline toxicity (also called narcosis) are helpful to estimate the minimum toxicity of chemicals to be tested and to identify excess toxicity in existing data sets. Here, we analyzed an existing fish embryo toxicity database and established a QSAR for fish embryo LC 50 using chemicals that were independently classified to act according to the non-specific mode of action of baseline toxicity. The octanol-water partition coefficient K ow is commonly applied to discriminate between non-polar and polar narcotics. Replacing the K ow by the liposome-water partition coefficient K lipw yielded a common QSAR for polar and non-polar baseline toxicants. This developed baseline toxicity QSAR was applied to compare the final mode of action (MOA) assignment of 132 chemicals. Further, we included the analysis of internal lethal concentration (ILC 50 ) and chemical activity (La 50 ) as complementary approaches to evaluate the robustness of the FET baseline toxicity. The analysis of the FET dataset revealed that specifically acting and reactive chemicals converged towards the baseline toxicity QSAR with increasing hydrophobicity. The developed FET baseline toxicity QSAR can be used to identify specifically acting or reactive compounds by determination of the toxic ratio and in combination with appropriate endpoints to infer the MOA for chemicals. Copyright © 2016 Elsevier Ltd. All rights reserved.

Acute and chronic toxicity study of the water accommodated fraction (WAF), chemically enhanced WAF (CEWAF) of crude oil and dispersant in the rock pool copepod Tigriopus japonicus.

PubMed

Lee, Kyun-Woo; Shim, Won Joon; Yim, Un Hyuk; Kang, Jung-Hoon

2013-08-01

We determined the toxicity of the water accommodated hydrocarbon fraction (WAF), two chemically enhanced WAFs (CEWAFs; CEWAF-C, Crude oil+Corexit 9500 and CEWAF-H, Crude oil+Hiclean) of crude oil and two dispersants (Corexit 9500 and Hiclean) to the rock pool copepod Tigriopus japonicus. In the acute toxicity test, Corexit 9500 was the most toxic of all the chemicals studied. The nauplius stage of T. japonicus was more susceptible to the toxic chemicals studied than the adult female. The toxicity data using the nauplius stage was then considered as baseline to determine the spiking concentration of chemicals for chronic toxicity tests on the copepod. As the endpoints in the chronic toxicity test, survival, sex ratio, developmental time and fecundity of the copepod were used. All chemicals used in this study resulted in increased toxicity in the F1 generation. The lowest-observed-adverse-effect (LOAE) concentrations of WAF, CEWAF-H, CEWAF-C, Hiclean and Corexit 9500 were observed to be 50%, 10%, 0.1%, 1% and 1%, respectively. The results in present study imply that copepods in marine may be negatively influenced by spilled oil and dispersant. Copyright © 2013 Elsevier Ltd. All rights reserved.

Implication of global environmental changes on chemical toxicity-effect of water temperature, pH, and ultraviolet B irradiation on acute toxicity of several pharmaceuticals in Daphnia magna.

PubMed

Kim, Jungkon; Park, Jeongim; Kim, Pan-Gyi; Lee, Chulwoo; Choi, Kyunghee; Choi, Kyungho

2010-04-01

Global environmental change poses emerging environmental health challenges throughout the world. One of such threats could be found in chemical safety in aquatic ecosystem. In the present study, we evaluated the effect of several environmental factors, such as water pH, temperature and ultraviolet light on the toxicity of pharmaceutical compounds in water, using freshwater invertebrate Daphnia magna. Seven pharmaceuticals including ibuprofen, acetaminophen, lincomycin, ciprofloxacin, enrofloxacin, chlortetracycline and sulfathiazole were chosen as test compounds based on their frequent detection in water. The experimental conditions of environmental parameters were selected within the ranges that could be encountered in temperate environment, i.e., water temperature (15, 21, and 25 degrees C), pH (7.4, 8.3, and 9.2), and UV-B light intensity (continuous irradiation of 15.0 microW/cm(2)). For acetaminophen, enrofloxacin and sulfathiazole, decrease in water pH generally led to increase of acute lethal toxicity, which could be explained by the unionized fraction of pharmaceuticals. Increase of water temperature enhanced the acute toxicity of the acetaminophen, enrofloxacin and chlortetracycline, potentially due to alteration in toxicokinetics of chemicals as well as impact on physiological mechanisms of the test organism. The presence of UV-B light significantly increased the toxicity of sulfathiazole, which could be explained by photo-modification of this chemical that lead to oxidative stress. Under the UV light, however, acute toxicity of enrofloxacin decreased, which might be due to photo-degradation. Since changing environmental conditions could affect exposure and concentration-response profile of environmental contaminants, such conditions should be identified and evaluated in order to better manage ecosystem health under changing global environment.

Chemical composition and photochemical reactivity of exhaust from aircraft turbine engines

NASA Astrophysics Data System (ADS)

Spicer, C. W.; Holdren, M. W.; Riggin, R. M.; Lyon, T. F.

1994-10-01

Assessment of the environmental impact of aircraft emissions is required by planners and policy makers. Seveal areas of concern are: 1. exposure of airport workers and urban residents to toxic chemicals emitted when the engines operate at low power (idle and taxi) on the ground; 2. contributions to urban photochemical air pollution of aircraft volatile organic and nitrogen oxides emissions from operations around airports; and 3. emissions of nitrogen oxides and particles during high-altitude operation. The environmental impact of chemicals emitted from jet aircraft turbine engines has not been firmly established due to lack of data regarding emission rates and identities of the compounds emitted. This paper describes an experimental study of two different aircraft turbine engines designed to determine detailed organic emissions, as well as emissions of inorganic gases. Emissions were measured at several engine power settings. Measurements were made of detailed organic composition from C1 through C17, CO, CO2, NO, NOx, and polycyclic aromatic hydrocarbons. Measurements were made using a multi-port sampling pro be positioned directly behind the engine in the exhaust exit plane. The emission measurements have been used to determine the organic distribution by carbon number and the distribution by compound class at each engine power level. The sum of the organic species was compared with an independent measurement of total organic carbon to assess the carbon mass balance. A portion of the exhaust was captured and irradiated in outdoor smog chambers to assess the photochemical reactivity of the emissions with respect to ozone formation. The reactivity of emissions from the two engines was apportioned by chemical compound class.

Acute toxicity of firefighting chemical formulations to four life stages of fathead minnow

USGS Publications Warehouse

Gaikowski, Mark P.; Hamilton, Steve J.; Buhl, Kevin J.; McDonald, Susan F.; Summers, Cliff H.

1996-01-01

Laboratory studies were conducted with four early life stages of fathead minnow,Pimephales promelas,to determine the acute toxicity of five firefighting chemical formulations in standardized soft and hard water. Egg, fry, 30-day posthatch, and 60-day posthatch life stages were tested with three fire retardants (Fire-Trol GTS-R, Fire-Trol LCG-R, and Phos-Chek D75-F) and two fire-suppressant foams (Phos-Chek WD-881 and Ansul Silv-Ex). Fry were generally the most sensitive life stage tested, whereas the eggs were the least sensitive life stage. Formulation toxicity was greater in hard water than in soft water for all life stages tested. Fire-suppressant foams were more toxic than the fire retardants. The 96-hr LC50s derived for fathead minnows were rank ordered from the most toxic to the least toxic formulation as follows: Phos-Chek WD-881 (13a??32 mg/liter) > Silv-Ex (19a??32 mg/liter) > Fire-Trol GTS-R (135a??787 mg/liter) > Phos-Chek D75-F (168a??2250 mg/liter) > Fire-Trol LCG-R (519a??6705 mg/liter) (ranges are the lowest and highest 96-hr LC50for each formulation). (C) 1996 Academic Press, Inc.

Larvicidal efficacies and chemical composition of essential oils of Pinus sylvestris and Syzygium aromaticum against mosquitoes

PubMed Central

Fayemiwo, Kehinde Adenike; Adeleke, Monsuru Adebayo; Okoro, Ovie Princewill; Awojide, Shola Hezekiah; Awoniyi, Ilias Olufemi

2014-01-01

Objective To assess the chemical composition and mosquito larvicidal potentials of essential oils of locally sourced Pinus sylvestris (P. sylvestris) and Syzygium aromaticum (S. aromaticum) against Aedes aegypti (A. aegypti) and Culex quinquefasciatus (C. quinquefasciatus). Method The chemical composition of the essential oils of both plants was determined using GC-MS while the larvicidal bioassay was carried out using different concentrations of the oils against the larvae of A. aegypti and C. quinquefasciatus in accordance with the standard protocol. Results The results as determined by GC-MS showed that oil of S. aromaticum has eugenol (80.5%) as its principal constituent while P. sylvestris has 3-Cyclohexene-1-methanol, .alpha., .alpha.4-trimethyl (27.1%) as its dominant constituent. Both oils achieved over 85% larval mortality within 24 h. The larvae of A. aegypti were more susceptible to the oils [LC50 (S. aromaticum)=92.56 mg/L, LC50(P. sylvestris)=100.39 mg/L] than C. quinquefasciatus [LC50(S. aromaticum)=124.42 mg/L; LC50(P. sylvestris)=128.00 mg/L]. S. aromaticum oil was more toxic to the mosquito larvae than oil of P. sylvestris but the difference in lethal concentrations was insignificant (P>0.05). Conclusion The results justify the larvicidal potentials of both essential oils and the need to incorporate them in vector management and control. PMID:24144127

Saffron as an antidote or a protective agent against natural or chemical toxicities.

PubMed

Razavi, Bibi Marjan; Hosseinzadeh, Hossein

2015-05-01

Saffron (Crocus sativus) is an extensively used food additive for its color and taste. Since ancient times this plant has been introduced as a marvelous medicine throughout the world. The wide spectrum of saffron pharmacological activities is related to its major constituents including crocin, crocetin and safranal. Based on several studies, saffron and its active ingredients have been used as an antioxidant, antiinflammatory and antinociceptive, antidepressant, antitussive, anticonvulsant, memory enhancer, hypotensive and anticancer. According to the literatures, saffron has remarkable therapeutic effects. The protective effects of saffron and its main constituents in different tissues including brain, heart, liver, kidney and lung have been reported against some toxic materials either natural or chemical toxins in animal studies.In this review article, we have summarized different in vitro and animal studies in scientific databases which investigate the antidotal and protective effects of saffron and its major components against natural toxins and chemical-induced toxicities. Due to the lake of human studies, further investigations are required to ascertain the efficacy of saffron as an antidote or a protective agent in human intoxication.

Evaluation of an adherent mouse embryonic stem cell in vitro assay to predict developmental toxicity of ToxCast chemicals.

EPA Science Inventory

The potential for most environmental chemicals to produce developmental toxicity is unknown. Mouse embryonic stem cell (mESC) assays are an alternative in vitro model to assess chemicals. The chemical space evaluated using mESC and compared to in vivo is limited. We used an adher...

Discriminating toxicant classes by mode of action. 1. (Eco)toxicity profiles.

PubMed

Nendza, Monika; Wenzel, Andrea

2006-05-01

Predictive toxicology, particularly quantitative structure-activity relationships (QSARs), require classification of chemicals by mode of action (MOA). MOA is, however, not a constant property of a compound but it varies between species and may change with concentration and duration of exposure. A battery of MOA-specific in-vitro and low-complexity assays, featuring biomolecular targets for major classes of environmental pollutants, provides characteristic responses for (1.) classification of chemicals by MOA, (2.) identification of (eco)toxicity profiles of chemicals, (3.) identification of chemicals with specific MOAs, (4.) indication of most sensitive species, (5.) identification of chemicals that are outliers in QSARs and (6.) selection of appropriate QSARs for predictions. Chemicals covering nine distinct modes of toxic action (non-polar non-specific toxicants (n=14), polar non-specific toxicants (n=18), uncouplers of oxidative phosphorylation (n=25), inhibitors of photosynthesis (n=15), inhibitors of acetylcholinesterase (n=14), inhibitors of respiration (n=3), thiol-alkylating agents (n=9), reactives (irritants) (n=8), estrogen receptor agonists (n=9)) were tested for cytotoxicity in the neutralred assay, oxygen consumption in isolated mitochondria, oxygen production in algae, inhibition of AChE, reaction with GSH and activity in the yeast estrogen receptor assay. Data on in-vivo aquatic toxicity (LC50, EC50) towards fish, daphnids, algae and bacteria were collected from the literature for reasons of comparison and reference scaling. In the MOA-specific in-vitro test battery, most test chemicals are specifically active at low concentrations, though multiple effects do occur. Graphical and statistical evaluation of the individual classes versus MOA 1 (non-polar non-specific toxicants) identifies interactions related to predominant MOA. Discriminant analyses (DA) on subsets of the data revealed correct classifications between 70% (in-vivo data) and >90% (in

Classification of baseline toxicants for QSAR predictions to replace fish acute toxicity studies.

PubMed

Nendza, Monika; Müller, Martin; Wenzel, Andrea

2017-03-22

Fish acute toxicity studies are required for environmental hazard and risk assessment of chemicals by national and international legislations such as REACH, the regulations of plant protection products and biocidal products, or the GHS (globally harmonised system) for classification and labelling of chemicals. Alternative methods like QSARs (quantitative structure-activity relationships) can replace many ecotoxicity tests. However, complete substitution of in vivo animal tests by in silico methods may not be realistic. For the so-called baseline toxicants, it is possible to predict the fish acute toxicity with sufficient accuracy from log K ow and, hence, valid QSARs can replace in vivo testing. In contrast, excess toxicants and chemicals not reliably classified as baseline toxicants require further in silico, in vitro or in vivo assessments. Thus, the critical task is to discriminate between baseline and excess toxicants. For fish acute toxicity, we derived a scheme based on structural alerts and physicochemical property thresholds to classify chemicals as either baseline toxicants (=predictable by QSARs) or as potential excess toxicants (=not predictable by baseline QSARs). The step-wise approach identifies baseline toxicants (true negatives) in a precautionary way to avoid false negative predictions. Therefore, a certain fraction of false positives can be tolerated, i.e. baseline toxicants without specific effects that may be tested instead of predicted. Application of the classification scheme to a new heterogeneous dataset for diverse fish species results in 40% baseline toxicants, 24% excess toxicants and 36% compounds not classified. Thus, we can conclude that replacing about half of the fish acute toxicity tests by QSAR predictions is realistic to be achieved in the short-term. The long-term goals are classification criteria also for further groups of toxicants and to replace as many in vivo fish acute toxicity tests as possible with valid QSAR

Engineering membrane and cell-wall programs for tolerance to toxic chemicals: Beyond solo genes.

PubMed

Sandoval, Nicholas R; Papoutsakis, Eleftherios T

2016-10-01

Metabolite toxicity in microbes, particularly at the membrane, remains a bottleneck in the production of fuels and chemicals. Under chemical stress, native adaptation mechanisms combat hyper-fluidization by modifying the phospholipids in the membrane. Recent work in fluxomics reveals the mechanism of how membrane damage negatively affects energy metabolism while lipidomic and transcriptomic analyses show that strains evolved to be tolerant maintain membrane fluidity under stress through a variety of mechanisms such as incorporation of cyclopropanated fatty acids, trans-unsaturated fatty acids, and upregulation of cell wall biosynthesis genes. Engineered strains with modifications made in the biosynthesis of fatty acids, peptidoglycan, and lipopolysaccharide have shown increased tolerance to exogenous stress as well as increased production of desired metabolites of industrial importance. We review recent advances in elucidation of mechanisms or toxicity and tolerance as well as efforts to engineer the bacterial membrane and cell wall. Copyright © 2016 Elsevier Ltd. All rights reserved.

Absolute parameters and chemical composition of the binary star OU Gem

NASA Astrophysics Data System (ADS)

Glazunova, L. V.; Mishenina, T. V.; Soubiran, C.; Kovtyukh, V. V.

2014-10-01

The absolute parameters and chemical composition of the BY Dra-type spectroscopic binary OU Gem (HD 45088) were determined on the basis of 10 high-resolution spectra. A new orbital solution of the binary system was determined, the binary ephemerides were specified, and the main physical and atmospheric parameters of the binary components were obtained. The chemical composition of both components was estimated for the first time for the stars of such type.

Size- and composition-dependent toxicity of synthetic and soil-derived Fe oxide colloids for the nematode Caenorhabditis elegans.

PubMed

Höss, Sebastian; Fritzsche, Andreas; Meyer, Carolin; Bosch, Julian; Meckenstock, Rainer U; Totsche, Kai Uwe

2015-01-06

Colloidal iron oxides (FeOx) are increasingly released to the environment due to their use in environmental remediation and biomedical applications, potentially harming living organisms. Size and composition could affect the bioavailability and toxicity of such colloids. Therefore, we investigated the toxicity of selected FeOx with variable aggregate size and variably composed FeOx-associated organic matter (OM) toward the nematode Caenorhabditis elegans. Ferrihydrite colloids containing citrate were taken up by C. elegans with the food and accumulated inside their body. The toxicity of ferrihydrite, goethite, and akaganeite was dependent on aggregate size and specific surface area, with EC50 values for reproduction ranging from 4 to 29 mg Fe L(-1). Experiments with mutant strains lacking mitochondrial superoxide dismutase (sod-2) showed oxidative stress for two FeOx and Fe(3+)-ions, however, revealed that it was not the predominant mechanism of toxicity. The OM composition determined the toxicity of mixed OM-FeOx phases on C. elegans. FeOx associated with humic acids or citrate were less toxic than OM-free FeOx. In contrast, soil-derived ferrihydrite, containing proteins and polysaccharides from mobile OM, was even more toxic than OM-free Fh of similar aggregate size. Consequently, the careful choice of the type of FeOx and the type of associated OM may help in reducing the ecological risks if actively applied to the subsurface.

WOOD STOVE EMISSIONS: PARTICLE SIZE AND CHEMICAL COMPOSITION

EPA Science Inventory

The report summarizes wood stove particle size and chemical composition data gathered to date. [NOTE: In 1995, EPA estimated that residential wood combustion (RWC), including fireplaces, accounted for a significant fraction of national particulate matter with aerodynamic diameter...

TOXICITY SCREENING WITH ZEBRAFISH ASSAY

EPA Science Inventory

The proposed toxicity screening will help EPA to prioritize chemicals for further testing, and it may also alert chemical manufacturers that some of their commercial products may be toxic. The proposed toxicity pathway studies will improve the research community’s abi...

Environmental phototoxicity: Solar ultraviolet radiation affects the toxicity of natural and man-made chemicals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larson, R.A.; Berenbaum, M.R.

1988-04-01

Ultraviolet radiation appears to be toxic to all forms of unpigmented living cells, including bacteria, protozoa, nematodes, arthropods, fish, birds, and mammals. In addition to the direct absorption of solar energy by cellular constituents, toxicity may occur because of the absorption of sunlight by xenobiotics (or by naturally occurring compounds outside the target cell); these may be converted by light or by subsequent light-promoted reactions that induce cellular damage. This article describes the phototoxicity of photodynamic dyes, light-activated synthetic herbicides, petroleum and its constituents, and naturally occurring chemicals from plants. Detoxification mechanisms are also discussed.

Virtual Liver: integrating in vitro and in vivo data to predict chemical-induced toxicity

EPA Science Inventory

It is difficult to assess the health impact of long-term exposure to low levels of contaminants from animal studies. Current methods for testing the toxicity of a single chemical can cost millions of dollars, take up to two years and sacrifice thousands of animals. In vitro model...

Cheminformatics Analysis of EPA ToxCast Chemical Libraries to Identify Domains of Applicability for Predictive Toxicity Models and Prioritize Compounds for Toxicity Testing

EPA Science Inventory

An important goal of toxicology research is the development of robust methods that use in vitro and chemical structure information to predict in vivo toxicity endpoints. The US EPA ToxCast program is addressing this goal using ~600 in vitro assays to create bioactivity profiles o...

Rapid, Contactless and Non-Destructive Testing of Chemical Composition of Samples

NASA Astrophysics Data System (ADS)

Ivanov, O.; Vaseashta, A.; Stoychev, L.

Our results demonstrate that a new effect can be induced in each solid in a wide spectral range of electromagnetic irradiation. In the present manuscript we prove experimentally that one of the possible applications of this effect is for an express contactless control of the chemical composition of a series of samples, in this case, coins. The method has wide applicability ranging from defense and homeland security to several applications requiring rapid and nondestructive identification of chemical composition.

Chemical Composition, Anticonvulsant Activity, and Toxicity of Essential Oil and Methanolic Extract of Elettaria cardamomum.

PubMed

Masoumi-Ardakani, Yaser; Mandegary, Ali; Esmaeilpour, Khadijeh; Najafipour, Hamid; Sharififar, Fariba; Pakravanan, Mahboobeh; Ghazvini, Hamed

2016-11-01

Elettaria cardamomum is an aromatic spice (cardamom) native to the humid Asian areas, which contains some compounds with a potential anticonvulsant activity. Various pharmacological properties such as anti-inflammatory, analgesic, antioxidant, and antimicrobial effects have been related to this plant. This research was conducted to examine the probable protective impact of the essential oil and methanolic extract of E. cardamomum against chemically (pentylentetrazole)- and electrically (maximal electroshock)-induced seizures in mice. In addition, neurotoxicity, acute lethality, and phytochemistry of the essential oil and methanolic extract were estimated. The TLC method showed the presence of kaempferol, rutin, and quercetin in the extract, and the concentration of quercetin in the extract was 0.5 µg/mL. The major compounds in the essential oil were 1,8-cineole (45.6 %), α -terpinyl acetate (33.7 %), sabinene (3.8 %), 4-terpinen-4-ol (2.4 %), and myrcene (2.2 %), respectively. The extract and essential oil showed significant neurotoxicity in the rotarod test at the doses of 1.5 g/kg and 0.75 mL/kg, respectively. No mortalities were observed up to the doses of 2 g/kg and 0.75 mL/kg for the extract and essential oil. The essential oil was effective in both the pentylentetrazole and maximal electroshock models; however, the extract was only effective in the pentylentetrazole model. The study suggested that E. cardamomum methanolic extract had no significant lethality in mice. Both the essential oil and methanolic extract showed movement toxicity. Anticonvulsant effects of E. cardamomum were negligible against the seizures induced by pentylentetrazole and maximal electroshock. Georg Thieme Verlag KG Stuttgart · New York.

Acute toxicity and chemical evaluation of coking wastewater under biological and advanced physicochemical treatment processes.

PubMed

Dehua, Ma; Cong, Liu; Xiaobiao, Zhu; Rui, Liu; Lujun, Chen

2016-09-01

This study investigated the changes of toxic compounds in coking wastewater with biological treatment (anaerobic reactor, anoxic reactor and aerobic-membrane bioreactor, A1/A2/O-MBR) and advanced physicochemical treatment (Fenton oxidation and activated carbon adsorption) stages. As the biological treatment stages preceding, the inhibition effect of coking wastewater on the luminescence of Vibrio qinghaiensis sp. Nov. Q67 decreased. Toxic units (TU) of coking wastewater were removed by A1/A2/O-MBR treatment process, however approximately 30 % TU remained in the biologically treated effluent. There is a tendency that fewer and fewer residual organic compounds could exert equal acute toxicity during the biological treatment stages. Activated carbon adsorption further removed toxic pollutants of biologically treated effluent but the Fenton effluent increased acute toxicity. The composition of coking wastewater during the treatment was evaluated using the three-dimensional fluorescence spectra, gas chromatography-mass spectrometry (GC-MS). The organic compounds with high polarity were the main cause of acute toxicity in the coking wastewater. Aromatic protein-like matters in the coking wastewater with low biodegradability and high toxicity contributed mostly to the remaining acute toxicity of the biologically treated effluents. Chlorine generated from the oxidation process was responsible for the acute toxicity increase after Fenton oxidation. Therefore, the incorporation of appropriate advanced physicochemical treatment process, e.g., activated carbon adsorption, should be implemented following biological treatment processes to meet the stricter discharge standards and be safer to the environment.

Chemically Active, Porous 3D-Printed Thermoplastic Composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, Kent A.; Kennedy, Zachary C.; Arey, Bruce W.

Metal-organic frameworks (MOFs) exhibit exceptional properties and are widely investigated because of their structural and functional versatility relevant to catalysis, separations, and sensing applications. However, their commercial or large-scale application is often limited by their powder forms. To address this, we report the production of MOF-thermoplastic polymer composites accessed via a standard 3D printer. MOFs (Zeolitic imidazolate framework; ZIF-8) were successfully incorporated homogeneously into both poly(lactic acid) (PLA) and thermoplastic polyurethane (TPU) matrices, extruded into filaments, and utilized for on-demand access to 3D structures by fused-deposition modeling. Printed rigid PLA-MOF composites displayed good structural integrity, high surface area ((SA)avg =more » 531 m2 g-1) and hierarchical pore features. Flexible TPU-MOF composites (SAavg = 706 m2 g-1) were achieved by employing a sacrificial fluoropolymer readily removed post-printing. Critically, embedded particles in the plastic matrices retain their ability to participate in chemical interactions characteristic of the parent MOF. The fabrication strategies can be extended to other MOFs and illustrate the potential of 3D printing to create unique porous and high surface area chemically-active structures.« less

Numerical Validation of Chemical Compositional Model for Wettability Alteration Processes

NASA Astrophysics Data System (ADS)

Bekbauov, Bakhbergen; Berdyshev, Abdumauvlen; Baishemirov, Zharasbek; Bau, Domenico

2017-12-01

Chemical compositional simulation of enhanced oil recovery and surfactant enhanced aquifer remediation processes is a complex task that involves solving dozens of equations for all grid blocks representing a reservoir. In the present work, we perform a numerical validation of the newly developed mathematical formulation which satisfies the conservation laws of mass and energy and allows applying a sequential solution approach to solve the governing equations separately and implicitly. Through its application to the numerical experiment using a wettability alteration model and comparisons with existing chemical compositional model's numerical results, the new model has proven to be practical, reliable and stable.

Global chemical composition of ambient fine particulate matter for exposure assessment.

PubMed

Philip, Sajeev; Martin, Randall V; van Donkelaar, Aaron; Lo, Jason Wai-Ho; Wang, Yuxuan; Chen, Dan; Zhang, Lin; Kasibhatla, Prasad S; Wang, Siwen; Zhang, Qiang; Lu, Zifeng; Streets, David G; Bittman, Shabtai; Macdonald, Douglas J

2014-11-18

Epidemiologic and health impact studies are inhibited by the paucity of global, long-term measurements of the chemical composition of fine particulate matter. We inferred PM2.5 chemical composition at 0.1° × 0.1° spatial resolution for 2004-2008 by combining aerosol optical depth retrieved from the MODIS and MISR satellite instruments, with coincident profile and composition information from the GEOS-Chem global chemical transport model. Evaluation of the satellite-model PM2.5 composition data set with North American in situ measurements indicated significant spatial agreement for secondary inorganic aerosol, particulate organic mass, black carbon, mineral dust, and sea salt. We found that global population-weighted PM2.5 concentrations were dominated by particulate organic mass (11.9 ± 7.3 μg/m(3)), secondary inorganic aerosol (11.1 ± 5.0 μg/m(3)), and mineral dust (11.1 ± 7.9 μg/m(3)). Secondary inorganic PM2.5 concentrations exceeded 30 μg/m(3) over East China. Sensitivity simulations suggested that population-weighted ambient PM2.5 from biofuel burning (11 μg/m(3)) could be almost as large as from fossil fuel combustion sources (17 μg/m(3)). These estimates offer information about global population exposure to the chemical components and sources of PM2.5.

Global Chemical Composition of Ambient Fine Particulate Matter for Exposure Assessment

PubMed Central

2015-01-01

Epidemiologic and health impact studies are inhibited by the paucity of global, long-term measurements of the chemical composition of fine particulate matter. We inferred PM2.5 chemical composition at 0.1° × 0.1° spatial resolution for 2004–2008 by combining aerosol optical depth retrieved from the MODIS and MISR satellite instruments, with coincident profile and composition information from the GEOS-Chem global chemical transport model. Evaluation of the satellite-model PM2.5 composition data set with North American in situ measurements indicated significant spatial agreement for secondary inorganic aerosol, particulate organic mass, black carbon, mineral dust, and sea salt. We found that global population-weighted PM2.5 concentrations were dominated by particulate organic mass (11.9 ± 7.3 μg/m3), secondary inorganic aerosol (11.1 ± 5.0 μg/m3), and mineral dust (11.1 ± 7.9 μg/m3). Secondary inorganic PM2.5 concentrations exceeded 30 μg/m3 over East China. Sensitivity simulations suggested that population-weighted ambient PM2.5 from biofuel burning (11 μg/m3) could be almost as large as from fossil fuel combustion sources (17 μg/m3). These estimates offer information about global population exposure to the chemical components and sources of PM2.5. PMID:25343705

Global Chemical Composition of Ambient Fine Particulate Matter for Exposure Assessment

DOE PAGES

Philip, Sajeev; Martin, Randall V.; van Donkelaar, Aaron; ...

2014-10-24

Epidemiologic and health impact studies are inhibited by the paucity of global, long-term measurements of the chemical composition of fine particulate matter. We inferred PM 2.5 chemical composition at 0.1° × 0.1° spatial resolution for 2004–2008 by combining aerosol optical depth retrieved from the MODIS and MISR satellite instruments, with coincident profile and composition information from the GEOS-Chem global chemical transport model. Evaluation of the satellite-model PM 2.5 composition data set with North American in situ measurements indicated significant spatial agreement for secondary inorganic aerosol, particulate organic mass, black carbon, mineral dust, and sea salt. We found that global population-weightedmore » PM 2.5 concentrations were dominated by particulate organic mass (11.9 ± 7.3 μg/m 3), secondary inorganic aerosol (11.1 ± 5.0 μg/m 3), and mineral dust (11.1 ± 7.9 μg/m 3). Secondary inorganic PM 2.5 concentrations exceeded 30 μg/m 3 over East China. Sensitivity simulations suggested that population-weighted ambient PM 2.5 from biofuel burning (11 μg/m 3) could be almost as large as from fossil fuel combustion sources (17 μg/m 3). In conclusion, these estimates offer information about global population exposure to the chemical components and sources of PM 2.5.« less

Priority screening of toxic chemicals and industry sectors in the U.S. toxics release inventory: a comparison of the life cycle impact-based and risk-based assessment tools developed by U.S. EPA.

PubMed

Lim, Seong-Rin; Lam, Carl W; Schoenung, Julie M

2011-09-01

Life Cycle Impact Assessment (LCIA) and Risk Assessment (RA) employ different approaches to evaluate toxic impact potential for their own general applications. LCIA is often used to evaluate toxicity potentials for corporate environmental management and RA is often used to evaluate a risk score for environmental policy in government. This study evaluates the cancer, non-cancer, and ecotoxicity potentials and risk scores of chemicals and industry sectors in the United States on the basis of the LCIA- and RA-based tools developed by U.S. EPA, and compares the priority screening of toxic chemicals and industry sectors identified with each method to examine whether the LCIA- and RA-based results lead to the same prioritization schemes. The Tool for the Reduction and Assessment of Chemical and other environmental Impacts (TRACI) is applied as an LCIA-based screening approach with a focus on air and water emissions, and the Risk-Screening Environmental Indicator (RSEI) is applied in equivalent fashion as an RA-based screening approach. The U.S. Toxic Release Inventory is used as the dataset for this analysis, because of its general applicability to a comprehensive list of chemical substances and industry sectors. Overall, the TRACI and RSEI results do not agree with each other in part due to the unavailability of characterization factors and toxic scores for select substances, but primarily because of their different evaluation approaches. Therefore, TRACI and RSEI should be used together both to support a more comprehensive and robust approach to screening of chemicals for environmental management and policy and to highlight substances that are found to be of concern from both perspectives. Copyright © 2011 Elsevier Ltd. All rights reserved.

Active foraging for toxic prey during gestation in a snake with maternal provisioning of sequestered chemical defences

PubMed Central

Kojima, Yosuke; Mori, Akira

2015-01-01

Many animals sequester dietary defensive compounds and incorporate them into the offspring, which protects the young against predation. One possible but poorly investigated question is whether females of such species actively prey upon toxic diets. The snake Rhabdophis tigrinus sequesters defensive steroids from toads consumed as prey; it also feeds on other amphibians. Females produce chemically armed offspring in direct proportion to their own level of toad-derived toxins by provisioning the toxins to their eggs. Our field observations of movements and stomach contents of radio-tracked R. tigrinus showed that gravid snakes preyed upon toads by actively foraging in the habitat of toads, even though toads were a scarce resource and toad-searching may incur potential costs. Our Y-maze experiments demonstrated that gravid females were more likely to trail the chemical cues of toads than were males or non-gravid females. These results showed behavioural switching in females and active foraging for scarce, toxic prey during gestation. Because exploitation of toads by gravid females results in their offspring being more richly endowed with prey-derived toxins, active foraging for toxic prey is expected to be an adaptive antipredator trait, which may enhance chemical defence in offspring. PMID:25392472

Active foraging for toxic prey during gestation in a snake with maternal provisioning of sequestered chemical defences.

PubMed

Kojima, Yosuke; Mori, Akira

2015-01-07

Many animals sequester dietary defensive compounds and incorporate them into the offspring, which protects the young against predation. One possible but poorly investigated question is whether females of such species actively prey upon toxic diets. The snake Rhabdophis tigrinus sequesters defensive steroids from toads consumed as prey; it also feeds on other amphibians. Females produce chemically armed offspring in direct proportion to their own level of toad-derived toxins by provisioning the toxins to their eggs. Our field observations of movements and stomach contents of radio-tracked R. tigrinus showed that gravid snakes preyed upon toads by actively foraging in the habitat of toads, even though toads were a scarce resource and toad-searching may incur potential costs. Our Y-maze experiments demonstrated that gravid females were more likely to trail the chemical cues of toads than were males or non-gravid females. These results showed behavioural switching in females and active foraging for scarce, toxic prey during gestation. Because exploitation of toads by gravid females results in their offspring being more richly endowed with prey-derived toxins, active foraging for toxic prey is expected to be an adaptive antipredator trait, which may enhance chemical defence in offspring. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

The US EPAs ToxCast Program for the Prioritization and Prediction of Environmental Chemical Toxicity

EPA Science Inventory

To meet the need for evaluating large numbers of chemicals for potential toxicity, the U.S. Environmental Protection Agency has initiated a research project call ToxCast that makes use of recent advances in molecular biology and high-throughput screening. These technologies have ...

Comparative Toxicity of Eight Oil Dispersants, Louisiana Sweet Crude Oil (LSC) and Chemically Dispersed LSC to Two Aquatic Test Species

EPA Science Inventory

This study describes the acute toxicity of eight commercial oil dispersants, Louisiana sweet crude oil (LSC), and chemically dispersed LSC. The approach utilized consistent test methodologies within a single laboratory in assessing the relative acute toxicity of the eight dispers...

Polypyrrole-MWCNT-Ag composites for electromagnetic shielding: Comparison between chemical deposition and UV-reduction approaches

NASA Astrophysics Data System (ADS)

Ebrahimi, Izadyar; Gashti, Mazeyar Parvinzadeh

2018-07-01

In this study, we focused on the synthesis of polypyrrole-MWCNT-Ag composites and we evaluated their electrical properties to determine the electromagnetic interference shielding performance. We reduced silver nanoparticles in composites using two different in situ methods: UV-reduction and chemical deposition. Composites were characterized using spectroscopic and microscopic tools for evaluation of the chemical, morphological, electrical conductivity and electromagnetic shielding effectiveness. Results from Fourier transform infrared spectroscopy and dispersive Raman microscope showed chemical interactions between silver and the polypyrrole-MWCNT composite due to the charge-transfer within the structure. X-ray diffraction confirmed appearance of two new peaks for silver nanoparticles embedded in polypyrrole-MWCNT independent to reduction method. According to microscopy images, silver nanoparticles were homogenously distributed at the PPy-MWCNTs interfaces by UV reduction, while, chemical reduction resulted to deposition of silver within the PPy matrix. Finally, our results revealed that the polypyrrole-MWCNT-Ag composite produced via UV-reduction has higher electrical conductivity and shielding effectiveness in comparison to chemically reduced one.

Calculating Toxic Corridors.

DTIC Science & Technology

1980-11-01

59 programmable calculator . Method 1 will most likely be used if there is a toxic corridor length table for the chemical; Method 2 if there is no table...experience of the forecaster in making this forecast, availability of a toxic corridor length table for the released chemical, and availability of a TI

Chemical Composition Variability of Essential Oils of Daucus gracilis Steinh. from Algeria.

PubMed

Benyelles, Batoul; Allali, Hocine; Dib, Mohamed El Amine; Djabou, Nassim; Paolini, Julien; Costa, Jean

2017-06-01

The chemical compositions of 20 Algerian Daucus gracilis essential oils were investigated using GC-FID, GC/MS, and NMR analyses. Altogether, 47 compounds were identified, accounting for 90 - 99% of the total oil compositions. The main components were linalool (18; 12.5 - 22.6%), 2-methylbutyl 2-methylbutyrate (20; 9.2 - 20.2%), 2-methylbutyl isobutyrate (10; 4.2 - 12.2%), ammimajane (47; 2.6 - 37.1%), (E)-β-ocimene (15; 0.2 - 12.8%) and 3-methylbutyl isovalerate (19; 3.3 - 9.6%). The chemical composition of the essential oils obtained from separate organs was also studied. GC and GC/MS analysis of D. gracilis leaves and flowers allowed identifying 47 compounds, amounting to 92.3% and 94.1% of total oil composition, respectively. GC and GC/MS analysis of D. gracilis leaf and flower oils allowed identifying linalool (22.7%), 2-methylbutyl 2-methylbutyrate (18.9%), 2-methylbutyl isovalerate (13.6%), ammimajane (10.4%), 3-methylbutyl isovalerate (10.3%), (E)-β-ocimene (8.4%) and isopentyl 2-methylbutyrate (8.1%) as main components. The chemical variability of the Algerian oil samples was studied using statistical analysis, which allowed the discrimination of three main Groups. A direct correlation between the altitudes, nature of soils and the chemical compositions of the D. gracilis essential oils was evidenced. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

Effects of toxic cyanobacteria and ammonia on flesh quality of blunt snout bream (Megalobrama amblycephala).

PubMed

Wang, Li; Chen, Chuanyue; Liu, Wanjing; Xia, Hu; Li, Jian; Zhang, Xuezhen

2017-03-01

Toxic cyanobacterial blooms result in the production of an organic biomass containing cyanotoxins (e.g. microcystins) and an elevated ammonia concentration in the water environment. The ingestion of toxic cyanobacteria and exposure to ammonia are grave hazards for fish. The present study assessed the effects of dietary toxic cyanobacteria and ammonia exposure on the flesh quality of blunt snout bream (Megalobrama amblycephala). Dietary toxic cyanobacteria and ammonia exposure had no impact on fish growth performance, fillet proximate composition and drip loss, whereas it significantly decreased fillet total amino acids, total essential amino acids, hardness and gumminess, and increased fillet ultimate pH as well as malondialdehyde content. However, there was no significant interaction between dietary toxic cyanobacteria and ammonia exposure on these parameters. Additionally, dietary toxic cyanobacteria significantly increased fillet initial pH, thaw loss and protein carbonyl content, whereas ammonia exposure did not. The results of the present study indicate that dietary toxic cyanobacteria and ammonia exposure reduced the quality of blunt snout bream fillet. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Classification of Chemicals Based On Structured Toxicity Information