Science.gov

Sample records for air toxics modeling

  1. COMMUNITY SCALE AIR TOXICS MODELING WITH CMAQ

    EPA Science Inventory

    Consideration and movement for an urban air toxics control strategy is toward a community, exposure and risk-based modeling approach, with emphasis on assessments of areas that experience high air toxic concentration levels, the so-called "hot spots". This strategy will requir...

  2. AIR TOXICS MODELING RESEARCH PROGRAM: AN OVERVIEW

    EPA Science Inventory

    This product is a Microsoft Powerpoint slide presentation which was given at the joint EPA Region 3 - Mid-Atlantic Regional Air Management Association (MARAMA) Air Toxic Summit in Philadelphia, Pennsylvania held from October 18, 2005 through October 20, 2005. The slide presentat...

  3. CONCENTRATIONS OF TOXIC AIR POLLUTANTS IN THE U.S. SIMULATED BY AN AIR QUALITY MODEL

    EPA Science Inventory

    As part of the US National Air Toxics Assessment, we have applied the Community Multiscale Air Quality Model, CMAQ, to study the concentrations of twenty gas-phase, toxic, hazardous air pollutants (HAPs) in the atmosphere over the continental United States. We modified the Carbo...

  4. AIR QUALITY MODELING OF PM AND AIR TOXICS AT NEIGHBORHOOD SCALES

    EPA Science Inventory

    The current interest in fine particles and toxics pollutants provide an impetus for extending air quality modeling capability towards improving exposure modeling and assessments. Human exposure models require information on concentration derived from interpolation of observati...

  5. POPULATION EXPOSURE AND DOSE MODEL FOR AIR TOXICS: A BENZENE CASE STUDY

    EPA Science Inventory

    The EPA's National Exposure Research Laboratory (NERL) is developing a human exposure and dose model called the Stochastic Human Exposure and Dose Simulation model for Air Toxics (SHEDS-AirToxics) to characterize population exposure to air toxics in support of the National Air ...

  6. Regional Air Toxics Modeling in California's San Francisco Bay Area

    NASA Astrophysics Data System (ADS)

    Martien, P. T.; Tanrikulu, S.; Tran, C.; Fairley, D.; Jia, Y.; Fanai, A.; Reid, S.; Yarwood, G.; Emery, C.

    2011-12-01

    Regional toxics modeling conducted for California's San Francisco Bay Area (SFBA) estimated potential cancer risk from diesel particulate matter (DPM) and four key reactive toxic gaseous pollutants (1,3-butadiene, benzene, formaldehyde, and acetaldehyde). Concentrations of other non-cancerous gaseous toxic air contaminants, including acrolein, were also generated. In this study, meteorological fields generated from July and December periods in 2000 and emissions from 2005 provided inputs to a three-dimensional air quality model at high spatial resolution (1x1 km^2 grid), from which a baseline set of annual risk values was estimated. Simulated risk maps show highest annual average DPM concentrations and cancer risks were located near and downwind of major freeways and near the Port of Oakland, a major container port in the area. Population weighted risks, using 2000 census data, were found to be highest in highly urbanized areas adjacent to significant DPM sources. For summer, the ratio of mean measured elemental carbon to mean modeled DPM was 0.78, conforming roughly to expectations. But for winter the ratio is 1.13, suggesting other sources of elemental carbon, such as wood smoke, are important. Simulated annual estimates for benzene and 1-3, butadiene compared well to measured annual estimates. Simulated acrolein and formaldehyde significantly under-predicted observed values. Simulations repeated using projected 2015 toxic emissions predicted that potential cancer risk dropped significantly in all areas throughout the SFBA. Emissions estimates for 2015 included the State of California's recently adopted on-road truck rule. Emission estimates of DPM are projected to drop about 70% between 2005 and 2015 in the SFBA, with a commensurate reduction in potential cancer risks. However, due to projected shifts in population during this period, with urban densification close to DPM sources outpacing emission reductions, there are some areas where population-weighted risks

  7. Validation of a novel air toxic risk model with air monitoring.

    PubMed

    Pratt, Gregory C; Dymond, Mary; Ellickson, Kristie; Thé, Jesse

    2012-01-01

    Three modeling systems were used to estimate human health risks from air pollution: two versions of MNRiskS (for Minnesota Risk Screening), and the USEPA National Air Toxics Assessment (NATA). MNRiskS is a unique cumulative risk modeling system used to assess risks from multiple air toxics, sources, and pathways on a local to a state-wide scale. In addition, ambient outdoor air monitoring data were available for estimation of risks and comparison with the modeled estimates of air concentrations. Highest air concentrations and estimated risks were generally found in the Minneapolis-St. Paul metropolitan area and lowest risks in undeveloped rural areas. Emissions from mobile and area (nonpoint) sources created greater estimated risks than emissions from point sources. Highest cancer risks were via ingestion pathway exposures to dioxins and related compounds. Diesel particles, acrolein, and formaldehyde created the highest estimated inhalation health impacts. Model-estimated air concentrations were generally highest for NATA and lowest for the AERMOD version of MNRiskS. This validation study showed reasonable agreement between available measurements and model predictions, although results varied among pollutants, and predictions were often lower than measurements. The results increased confidence in identifying pollutants, pathways, geographic areas, sources, and receptors of potential concern, and thus provide a basis for informing pollution reduction strategies and focusing efforts on specific pollutants (diesel particles, acrolein, and formaldehyde), geographic areas (urban centers), and source categories (nonpoint sources). The results heighten concerns about risks from food chain exposures to dioxins and PAHs. Risk estimates were sensitive to variations in methodologies for treating emissions, dispersion, deposition, exposure, and toxicity.

  8. Multiple Air-Toxics Exposure Study Working Paper Number 3. Urban air-toxics exposure model: development and application

    SciTech Connect

    Not Available

    1988-11-01

    The South Coast Air Quality Management District of California completed a Multiple Air Toxics Exposure Study (MATES) that examines the additive risk from a number of air toxics on an urban area. The project, though partially funded by EPA, is an example of how a State or local agency may approach assessing their local air-toxics risks as is encouraged by EPA's Urban Air Toxics Program which results from EPA's Air Toxic Strategy. The report is a summary of the methods used by the California agency. Though not intended as an endorsement of the entire contents of the report, EPA is reproducing their report (Working Paper Number 3) to benefit and encourage other agencies that may be contemplating such an assessment.

  9. Air quality modeling of selected aromatic and non-aromatic air toxics in the Houston urban and industrial airshed

    NASA Astrophysics Data System (ADS)

    Coarfa, Violeta Florentina

    2007-12-01

    Air toxics, also called hazardous air pollutants (HAPs), pose a serious threat to human health and the environment. Their study is important in the Houston area, where point sources, mostly located along the Ship Channel, mobile and area sources contribute to large emissions of such toxic pollutants. Previous studies carried out in this area found dangerous levels of different HAPs in the atmosphere. This thesis presents several studies that were performed for the aromatic and non-aromatic air toxics in the HGA. For these studies we developed several tools: (1) a refined chemical mechanism, which explicitly represents 18 aromatic air toxics that were lumped under two model species by the previous version, based on their reactivity with the hydroxyl radical; (2) an engineering version of an existing air toxics photochemical model that enables us to perform much faster long-term simulations compared to the original model, that leads to a 8--9 times improvement in the running time across different computing platforms; (3) a combined emission inventory based on the available emission databases. Using the developed tools, we quantified the mobile source impact on a few selected air toxics, and analyzed the temporal and spatial variation of selected aromatic and non-aromatic air toxics in a few regions within the Houston area; these regions were characterized by different emissions and environmental conditions.

  10. CMAQ MODELING FOR AIR TOXICS AT FINE SCALES: A PROTOTYPE STUDY

    EPA Science Inventory

    Toxic air pollutants (TAPs) or hazardous air pollutants (HAPs) exhibit considerable spatial and temporal variability across urban areas. Therefore, the ability of chemical transport models (CTMs), e.g. Community Multi-scale Air Quality (CMAQ), to reproduce the spatial and tempor...

  11. APPLICATION OF FINE SCALE AIR TOXICS MODELING WITH CMAQ TO HAPEM5

    EPA Science Inventory

    This paper provides a preliminary demonstration of the EPA neighborhood scale modeling paradigm for air toxics by linking concentration from the Community Multiscale Air Quality (CMAQ) modeling system to the fifth version of the Hazardous Pollutant Exposure Model (HAPEM5). For t...

  12. Baltimore Air Toxics Study (BATS)

    SciTech Connect

    Sullivan, D.A.

    1996-12-31

    The Baltimore Air Toxics Study is one of the three urban air toxics initiatives funded by EPA to support the development of the national air toxics strategy. As part of this project, the Air Quality Integrated Management System (AIMS) is under development. AIMS is designed to bring together the key components of urban air quality management into an integrated system, including emissions assessment, air quality modeling, and air quality monitoring. Urban area source emissions are computed for a wide range of pollutants and source categories, and are joined with existing point source emissions data. Measured air quality data are used to evaluate the adequacy of the emissions data and model treatments as a function of season, meteorological parameters, and daytime/nighttime conditions. Based on tested model performance, AIMS provides the potential to improve the ability to predict air quality benefits of alternative control options for criteria and toxic air pollutants. This paper describes the methods used to develop AIMS, and provides examples from its application in the Baltimore metropolitan area. The use of AIMS in the future to enhance environmental management of major industrial facilities also will be addressed in the paper.

  13. RESOLVING FINE SCALE IN AIR TOXICS MODELING AND THE IMPORTANCE OF ITS SUB-GRID VARIABILITY FOR EXPOSURE ESTIMATES

    EPA Science Inventory

    This presentation explains the importance of the fine-scale features for air toxics exposure modeling. The paper presents a new approach to combine local-scale and regional model results for the National Air Toxic Assessment. The technique has been evaluated with a chemical tra...

  14. MODELING AIR TOXICS AND PM 2.5 CONCENTRATION FIELDS AS A MEANS FOR FACILITATING HUMAN EXPOSURE ASSESSMENTS

    EPA Science Inventory

    The capability of the US EPA Models-3/Community Multiscale Air Quality (CMAQ) modeling system is extended to provide gridded ambient air quality concentration fields at fine scales. These fields will drive human exposure to air toxics and fine particulate matter (PM2.5) models...

  15. Comparing toxic air pollutant programs

    SciTech Connect

    Hawkins, S.C.

    1997-05-01

    This article compares state and federal toxic air pollutant programs. The Clean Air Act Ammendments created a program for the control of Hazardous Air Pollutants based on the establishment of control technology standards. State toxic programs can be classified into two categories: control technology-based and ambient concentration-based. Many states have opened to implement the MACT standards while enforcing their own state air toxics programs. Specific topics discussed include the following: the Federal air toxics program; existing state regulations; New Jersey Air Toxic Program; New York Toxics program.

  16. LINKING AIR TOXIC CONCENTRATIONS FROM CMAQ TO THE HAPEM5 EXPOSURE MODEL AT NEIGHORHOOD SCALES FOR THE PHILADELPHIA AREA

    EPA Science Inventory

    This paper provides a preliminary demonstration of the EPA neighborhood scale modeling paradigm for air toxics by linking concentration from the Community Multi-scale Air Quality (CMAQ) modeling system to the fifth version of the Hazardous Pollutant Exposure Model (HAPEM5). For ...

  17. FURTHER REFINEMENTS AND TESTING OF APEX3.0: EPA'S POPULATION EXPOSURE MODEL FOR CRITERIA AND AIR TOXIC INHALATION

    EPA Science Inventory

    The Air Pollutants Exposure Model (APEX(3.0)) is a PC-based model that was derived from the probabilistic NAAQS Exposure Model for carbon monoxide (pNEM/CO). APEX will be one of the tools used to estimate human population exposure for criteria and air toxic pollutants as part ...

  18. NATIONAL-SCALE ASSESSMENT OF AIR TOXICS RISKS

    EPA Science Inventory

    The national-scale assessment of air toxics risks is a modeling assessment which combines emission inventory development, atmospheric fate and transport modeling, exposure modeling, and risk assessment to characterize the risk associated with inhaling air toxics from outdoor sour...

  19. GIS modeling of air toxics releases from TRI-reporting and non-TRI-reporting facilities: impacts for environmental justice.

    PubMed

    Dolinoy, Dana C; Miranda, Marie Lynn

    2004-12-01

    The Toxics Release Inventory (TRI) requires facilities with 10 or more full-time employees that process > 25,000 pounds in aggregate or use > 10,000 pounds of any one TRI chemical to report releases annually. However, little is known about releases from non-TRI-reporting facilities, nor has attention been given to the very localized equity impacts associated with air toxics releases. Using geographic information systems and industrial source complex dispersion modeling, we developed methods for characterizing air releases from TRI-reporting as well as non-TRI-reporting facilities at four levels of geographic resolution. We characterized the spatial distribution and concentration of air releases from one representative industry in Durham County, North Carolina (USA). Inclusive modeling of all facilities rather than modeling of TRI sites alone significantly alters the magnitude and spatial distribution of modeled air concentrations. Modeling exposure receptors at more refined levels of geographic resolution reveals localized, neighborhood-level exposure hot spots that are not apparent at coarser geographic scales. Multivariate analysis indicates that inclusive facility modeling at fine levels of geographic resolution reveals exposure disparities by income and race. These new methods significantly enhance the ability to model air toxics, perform equity analysis, and clarify conflicts in the literature regarding environmental justice findings. This work has substantial implications for how to structure TRI reporting requirements, as well as methods and types of analysis that will successfully elucidate the spatial distribution of exposure potentials across geographic, income, and racial lines. PMID:15579419

  20. RESOLVING NEIGHBORHOOD-SCALE AIR TOXICS MODELING: A CASE STUDY IN WILMINGTON, CALIFORNIA

    EPA Science Inventory

    Air quality modeling is useful for characterizing exposures to air pollutants. While models typically provide results on regional scales, there is a need for refined modeling approaches capable of resolving concentrations on the scale of tens of meters, across modeling domains 1...

  1. Criteria air pollutants and toxic air pollutants.

    PubMed Central

    Suh, H H; Bahadori, T; Vallarino, J; Spengler, J D

    2000-01-01

    This review presents a brief overview of the health effects and exposures of two criteria pollutants--ozone and particulate matter--and two toxic air pollutants--benzene and formaldehyde. These pollutants were selected from the six criteria pollutants and from the 189 toxic air pollutants on the basis of their prevalence in the United States, their physicochemical behavior, and the magnitude of their potential health threat. The health effects data included in this review primarily include results from epidemiologic studies; however, some findings from animal studies are also discussed when no other information is available. Health effects findings for each pollutant are related in this review to corresponding information about outdoor, indoor, and personal exposures and pollutant sources. Images Figure 3 Figure 8 Figure 9 PMID:10940240

  2. Measurement of toxic and related air pollutants

    SciTech Connect

    Jayanty, R.K.M.; Gay, B.W. Jr.

    1990-12-01

    A joint conference for the fifth straight year cosponsored by the Air and Waste Management Association's EM-3, EM-4, and ITF-2 technical committees, and the Atmospheric Research and Exposure Assessment Laboratory (AREAL) of the US Environmental Protection Agency, was held in Raleigh, North Carolina, May 1-4, 1990. The technical program consisted of 187 presentations, held in 20 technical sessions, on recent advances in the measurement and monitoring of toxic and related pollutants found in ambient and source atmospheres. Covering a wide range of measurement topics and supported by 66 exhibitors of instrumentation and consulting services, the symposium was attended by more than 850 professionals from the US and other countries. This overview highlights a selection of the technical presentations. A synopsis of the keynote address to the symposium is also included. Presentations include: (1) radon, (2) atmospheric chemistry and fate of toxic pollutants, (3) supercritical fluid extraction, (4) acidic deposition, (5) determination of polar and volatile organic pollutants in ambient air, (6) Delaware Superfund innovative technology evaluation (SITE) study, (7) mobile sources emissions characterization, (8) Superfund site air monitoring, (9) exposure assessment, (10) chemometrics and environmental data analysis, (11) nicotine in environmental tobacco smoke, (12) source monitoring, (13) effects of air toxics on plants, (14) measurement of volatile organic pollutants, (15) general, (16) air pollution dispersion modeling, (17) measurement of hazardous waste emissions, (18) measurement of indoor toxic air contaminants, and (19) environmental quality assurance.

  3. Modeling and Impacts of Traffic Emissions on Air Toxics Concentrations near Roadways

    EPA Science Inventory

    The dispersion formulation incorporated in the U.S. Environmental Protection Agency’s AERMOD regulatory dispersion model is used to estimate the contribution of traffic-generated emissions of select VOCs – benzene, 1,3-butadiene, toluene – to ambient air concentrations at downwin...

  4. NEIGHBORHOOD SCALE MODELING OF PM 2.5 AND AIR TOXICS CONCENTRATION DISTRIBUTIONS TO DRIVE HUMAN EXPOSURE MODELS

    EPA Science Inventory

    Air quality (AQ) simulation models provide a basis for implementing the National Ambient Air Quality Standards (NAAQS) and are a tool for performing risk-based assessments and for developing environmental management strategies. Fine particulate matter (PM 2.5), its constituent...

  5. Groundwater air stripping: Effect on water toxicity

    SciTech Connect

    Eldridge, R.B.; Simpson, C.W.; Elliott, D.J.

    1995-02-01

    An air stripping unit was designed to reduce groundwater hydrocarbon content and biotoxicity to acceptable levels. A pilot plant study was conducted to determine the water treatability and to optimize the commercial unit design conditions. A measurement of the pilot plant effluent toxicity was obtained from {open_quotes}Microtox{close_quotes} analysis and rigorous bio-assays. These results indicated that reduction of the water hydrocarbon content to permitted discharge limits was accompanied by the elimination of water toxicity. The Onda mass transfer model was used to prepare the commercial unit design. A post-installation evaluation indicated that the model gave a good representation of the commercial unit performance. Toxicity reductions observed in the pilot plant were also observed in the commercial unit. 3 refs., 5 figs., 3 tabs.

  6. USING THE AIR QUALITY MODEL TO ANALYZE THE CONCENTRATIONS OF AIR TOXICS OVER THE CONTINENTAL U.S.

    EPA Science Inventory

    The U.S. Environmental Protection Agency is examining the concentrations and deposition of hazardous air pollutants (HAPs), which include a large number of chemicals, ranging from non reactive (i.e. carbon tetrachloride) to reactive (i.e. formaldehyde), exist in gas, aqueous, and...

  7. An assessment of air toxics in Minnesota.

    PubMed

    Pratt, G C; Palmer, K; Wu, C Y; Oliaei, F; Hollerbach, C; Fenske, M J

    2000-09-01

    We used monitoring and modeling to assess the concentrations of air toxics in the state of Minnesota. Model-predicted concentrations for 148 hazardous air pollutants were from the U.S. Environmental Protection Agency Cumulative Exposure Project (1990 data). Monitoring data consisted of samples of volatile organic compounds, carbonyls, and particulate matter [Less than and equal to] 10 microm in aerodynamic diameter collected at 25 sites throughout the state for varying periods of time (up to 8 years; 1991-1998). Ten pollutants exceeded health benchmark values at one or more sites by modeling, monitoring, or both (including acrolein, arsenic, benzene, 1,3-butadiene, carbon tetrachloride, chromium, chloroform, ethylene dibromide, formaldehyde, and nickel). Polycyclic organic matter also exceeded the benzo[a]pyrene health benchmark value assumed to represent this class of pollutants. The highest modeled and monitored concentrations of most pollutants were near the center of the Minneapolis-St. Paul metropolitan area; however, many smaller cities throughout the state also had elevated concentrations. Where direct comparisons were possible, monitored values often tended to exceed model estimates. Upper-bound excess lifetime inhalation cancer risks were estimated to range from 2.7 [times] 10(-5) to 140. 9 [times] 10(-5) (modeling) and 4.7 [times] 10(-5) to 11.0 [times] 10(-5) (using a smaller set of monitored carcinogens). Screening noncancer hazard indices summed over all end points ranged from 0.2 to 58.1 (modeling) and 0.6 to 2.0 (with a smaller set of monitored pollutants). For common sets of pollutants, the concentrations, cancer risks, and noncancer hazard indices were comparable between model-based estimates and monitored values. The inhalation cancer risk was apportioned to mobile sources (54%), area sources (22%), point sources (12%), and background (12%). This study provides evidence that air toxics are a public health concern in Minnesota.

  8. Chemical air pollutants and otorhinolaryngeal toxicity

    SciTech Connect

    Bisesi, M.S.; Rubin, A.M. . Occupational Health and Otolaryngology)

    1994-03-01

    Air pollution and the specific issue regarding the impact of airborne chemical agents to human health are familiar topics to most members of the environmental health science and environmental medicine communities. Some aspects, however, have received relatively less attention. Much has been published regarding the impact of air pollutants on the human upper and lower respiratory system, including interaction with the rhinologic (nasal) system. Relatively fewer data have been published, however, regarding the potential impact of air pollutants in reference specifically to the otologic (auditory and vestibular) and the laryngeal (larynx) system. Adverse impact to the ears, nose and throat, referred to as the otorhinolaryngeal system'', warrants attention as an important environmental health issue. Toxic interactions from exposure to many chemical air pollutants not only causes potential respiratory irritation and lung disease, but can also result in impaired hearing, balance, sense of smell, taste, and speech due to interaction with related target systems. This may be significant to environmental health risk assessment of chemical air pollutants if multi-target site models are considered.

  9. Implementing Title III -- Air toxics

    SciTech Connect

    Shaw, B.W.

    1995-12-31

    The South Coast Air Quality Management District (AQMD) is taking three basic approaches to implementing the new National Emissions Standards for Hazardous Air Pollutants (NESHAPs) from the Title III program: accept and implement, as written, the NESHAPs where few sources are located in the South Coast Air Basin; incorporate with simplification of the NESHAP requirements into AQMD rules when many sources are involved; then seek equivalency by the US EPA; and incorporate with a market-based rule (VOC RECLAIM), part of many NESHAPs which control volatile organic compound as HAPs. Whatever the approach, emphasis will be placed on: streamlining and simplification; helping sources understand requirements and comply; and common sense.

  10. Air toxics: sources and monitoring in Texas.

    PubMed Central

    Pendleton, D R

    1995-01-01

    Since the late 1980s, federal legislation has required industries to publicly report their annual emissions of toxic compounds. Industry reports show the largest contributor to toxic emission levels in Texas is the massive concentration of petrochemical industries along the Gulf Coast. It is interesting to note that although Texas produces over 50% of the nation's synthetic chemicals, it discharges less than 8% of the nation's toxic emissions. However, in response to growing concerns about the effects of these toxic emissions, the Texas Natural Resource Conservation Commission (TNRCC) initiated a long-term program for monitoring toxic chemicals in the air. This article provides details of this monitoring program as well as industry-funded toxic monitoring networks in Texas. This includes information on the technology currently being used for sample collection and analysis as well as plans for implementing methods that are on the technological horizon. Finally, details of some key measurements from the state's air toxics monitoring network will be provided along with an explanation of how they impact current air quality trends in Texas. PMID:8549477

  11. CAirTOX: A compartment model for assessing the fate of and human exposure to toxic-chemical emissions to air

    SciTech Connect

    McKone, T.E.

    1993-10-01

    CAirTOX has been developed as a spreadsheet model to assist in making a risk assessment of toxic air emissions. With CAirTOX, one can address how contaminants released to an air basin can lead to contamination of soil, food, surface water, and sediments. The modeling effort includes a multimedia transport and transformation model, exposure scenario models, and efforts to quantify uncertainty in multimedia, multiple-pathway exposure assessments. The multimedia transport and transformation model is a steady-state, but non-equilibrium model that can be used to assess concentrations of contaminants released continuously to air. In Part 1, the authors describe the multimedia transport and transformation model used to determine the fate of air emissions. In Part 2, they describe inputs and data needs for CAirTOX and the development of a set of landscape factors, which can be used to represent regional air basin/water-shed systems in California. In Part 3, they describe the multiple-pathway exposure scenarios and exposure algorithms. In Part 4, they compare the HRA approach and results and the CAirTOX exposure equations. In Part 5, they consider model sensitivity and uncertainty to determine how variability and uncertainty in model inputs affects the precision, accuracy, and credibility of the model output.

  12. Toxic effects of air freshener emissions.

    PubMed

    Anderson, R C; Anderson, J H

    1997-01-01

    To evaluate whether emissions of a commercial air freshener produced acute toxic effects in a mammalian species, the authors allowed male Swiss-Webster mice to breathe the emissions of one commercial-brand solid air freshener for 1 h. Sensory irritation and pulmonary irritation were evaluated with the ASTM-E-981 test. A computerized version of this test measured the duration of the break at the end of inspiration and the duration of the pause at the end of expiration--two parameters subject to alteration via respiratory effects of airborne toxins. Measurements of expiratory flow velocity indicated changes in airflow limitation. The authors then subjected mice to a functional observational battery, the purpose of which was to probe for changes in nervous system function. Emissions of this air freshener at several concentrations (including concentrations to which many individuals are actually exposed) caused increases in sensory and pulmonary irritation, decreases in airflow velocity, and abnormalities of behavior measured by the functional observational battery score. The test atmosphere was subjected to gas chromatography/mass spectroscopy, and the authors noted the presence of chemicals with known irritant and neurotoxic properties. The Material Safety Data Sheet for the air freshener indicated that there was a potential for toxic effects in humans. The air freshener used in the study did not diminish the effect of other pollutants tested in combination. The results demonstrated that the air freshener may have actually exacerbated indoor air pollution via addition of toxic chemicals to the atmosphere.

  13. Environmental air toxics: role in asthma occurrence?

    PubMed

    Larsen, Gary L; Beskid, Craig; Shirnamé-Moré, Lata

    2002-08-01

    The National Urban Air Toxics Research Center (NUATRC) hosted its first scientific workshop in 1994 that focused on possible relationships between air toxics and asthma. From that meeting came recommendations for future research including a need for more complete individual personal exposure assessments so that determinations of personal exposures to pollutants could be made. In the spring of 2001, NUATRC held a second such workshop to review progress made in this area during the intervening 7 years. Peer-reviewed articles from the workshop are published in this issue of (italic)Environmental Health Perspectives Supplements(/italic). As in 1994, academic, government, and industry scientists participated. Dave Guinnup of the Environmental Protection Agency discussed the nature of air toxics, their definition, and the basis for federal regulation. George Leikauf from the University of Cincinnati reviewed the 1994 workshop and subsequent research in this field. Current research funded by NUATRC that is addressing individual personal exposure was presented by Clifford Weisel (Environmental and Occupational Health Sciences Institute, University of Medicine and Dentistry of New Jersey), Patrick Kinney (Columbia University) and Candis Claiborn (Washington State University). David Corry from Baylor College of Medicine highlighted new insights into asthma pathogenesis while Stephen Redd from the Centers for Disease Control presented an overview of asthma epidemiology as well as the societal costs of the disease. Mary White (Agency for Toxic Substances and Disease Registry) discussed recent epidemiologic investigations by public health agencies into community concerns about asthma and hazardous air pollutants. David Peden (University of North Carolina) reviewed scientific studies into the links between asthma and air toxics as well as criteria air pollutants. In a session on occupational asthma, Lee Petsonk (National Institute for Occupational Safety and Health) discussed

  14. Air toxics regulatory issues facing urban settings.

    PubMed Central

    Olden, K; Guthrie, J

    1996-01-01

    Biomarker research does not exist in isolation. Its usefulness can only be realized when it is translated into prevention strategies to protect public health. In the context of air toxics, these prevention strategies begin with the development of regulatory standards derived from risk assessment schemes. The Clean Air Act Amendments of 1990 list 189 air toxics, including many volatile organics, metals, and pesticides. The National Institute of Environmental Health Sciences (NIEHS), through its affiliation with the National Toxicology Program, has generated toxicity and carcinogenicity data on more than 100 of these air toxics. The NIEHS extramural and intramural research portfolios support a variety of projects that develop and validate biomarkers for use in environmental health science and risk assessment. Biomarkers have a tremendous potential in the areas of regulating air toxics and protecting public health. Risk assessors need data provided by biomarkers of exposure, biomarkers of dose/pharmacokinetics, biomarkers of susceptibility or individual variability, and biomarkers of effects. The greatest benefit would be realized if biomarkers could be employed in four areas of primary and secondary prevention. The first is the use of biomarkers to enhance extrapolation of animal data to human exposure situations in establishing risk standards. The second is the use of biomarkers that assess noncancer, as well as cancer, end points. Important health end points include pulmonary dysfunction, immunotoxicity, and neurotoxicity. Third, biomarkers that serve as early waming signs to detect intermediate effects would enhance our ability to design timely and cost-effective intervention strategies. Finally, biomarkers used to evaluate the effectiveness of intervention strategies, both in clinical and regulatory settings, would enable us to ensure that programs designed to protect public health do, in fact, achieve the desired outcome. PMID:8933026

  15. Component modeling in ecological risk assessment: Disturbance in interspecific interactions caused by air toxics introduced into terrestrial ecosystems

    NASA Astrophysics Data System (ADS)

    Swider, Jan Zenon

    Ecological Risk Assessment standpoint and examine the impact of air toxics emissions on an ecosystem, with particular emphasis on predator-prey interactions. Such analysis may help to identify the most likely conditions leading to the ecosystem instability and possibility of its recuperation.

  16. Urban land use, air toxics and public health: Assessing hazardous exposures at the neighborhood scale

    SciTech Connect

    Corburn, Jason . E-mail: jtc2105@columbia.edu

    2007-03-15

    Land use data are increasingly understood as important indicators of potential environmental health risk in urban areas where micro-scale or neighborhood level hazard exposure data are not routinely collected. This paper aims to offer a method for estimating the distribution of air toxics in urban neighborhoods using land use information because actual air monitoring data rarely exist at this scale. Using Geographic Information System spatial modeling tools, we estimate air toxics concentrations across neighborhoods in New York City and statistically compare our model with the US Environmental Protection Agency's National Air Toxic Assessment and air monitoring data across three NYC neighborhoods. We conclude that land use data can act as a good proxy for estimating neighborhood scale air toxics, particularly in the absence of monitoring data. In addition, the paper suggests that land use data can expand the reach of environmental impact assessments that routinely exclude analyses of potential exposures to urban air toxics at the neighborhood scale.

  17. The Air Toxics Health Effects Database (ATHED)

    SciTech Connect

    Woodall, George M. Smith, Roy L.

    2008-11-15

    The Air Toxics Health Effects Database (ATHED) is currently used by the EPA's Office of Air Quality Planning and Standards (OAQPS) to support risk assessments for the Residual Risk Program. An assessment of the residual risk is required to be performed at a specified time (typically 8years) following the promulgation of a technology-based Maximum Achievable Control Technologies (MACT) standard. The goal of the Residual Risk Program is to assure that the risk that remains after MACT standards are implemented (i.e., the 'residual risk') is acceptable, and if not, to propose additional regulations to mitigate those risks. ATHED maintains all available reference values for each chemical as separate data records, and includes values for all exposure durations (acute, short-term, subchronic and chronic). These values are used as benchmarks to determine acceptable exposure levels to the hazardous air pollutants (HAPs) listed in Section 112 of the Clean Air Act. ATHED also provides useful background information on the uncertainty and/or modifying factors that were applied in the derivation of each reference value, as well as the point of departure and the critical study/studies. To facilitate comparisons across durations for a specific chemical, ATHED data can be graphically presented.

  18. Controlling air toxics through advanced coal preparation

    SciTech Connect

    Straszheim, W.E.; Buttermore, W.H.; Pollard, J.L.

    1995-11-01

    This project involves the assessment of advanced coal preparation methods for removing trace elements from coal to reduce the potential for air toxic emissions upon combustion. Scanning electron microscopy-based automated image analysis (SEM-AIA) and advanced washability analyses are being applied with state-of-the-art analytical procedures to predict the removal of elements of concern by advanced column flotation and to confirm the effectiveness of preparation on the quality of quantity of clean coal produced. Specific objectives are to maintain an acceptable recovery of combustible product, while improving the rejection of mineral-associated trace elements. Current work has focused on determining conditions for controlling column flotation system across its operating range and on selection and analysis of samples for determining trace element cleanability.

  19. Analysis of Mobile Source Air Toxics (MSATS)–Near-Road VOC and CarbonylConcentrations

    EPA Science Inventory

    This presentation examines data from a year-long study of measured near-road mobile source air toxic (MSAT) concentrations and compares these data with modeled 2005 National Air Toxic Assessment (NATA) results. Field study measurements were collected during a field campaign in ...

  20. LARGE-SCALE PREDICTIONS OF MOBILE SOURCE CONTRIBUTIONS TO CONCENTRATIONS OF TOXIC AIR POLLUTANTS

    EPA Science Inventory

    This presentation shows concentrations and deposition of toxic air pollutants predicted by a 3-D air quality model, the Community Multi Scale Air Quality (CMAQ) modeling system. Contributions from both on-road and non-road mobile sources are analyzed.

  1. EMISSIONS OF ORGANIC AIR TOXICS FROM OPEN BURNING

    EPA Science Inventory

    A detailed literature search was performed to collect and collate available data reporting emissions of toxic organic substances into the air from open burning sources. Availability of data varied according to the source and the class of air toxics of interest. Volatile organic c...

  2. Assessing exposure to air toxics relative to asthma.

    PubMed Central

    Weisel, Clifford P

    2002-01-01

    Asthma is a respiratory disease whose prevalence has been increasing since the mid 1970s and that affects more than 14.6 million residents of the United States. Environmental triggers of asthma include air pollutants that are respiratory irritants. Air toxics emitted into the ambient air are listed in the 1990 Clean Air Act Amendments as hazardous air pollutants (HAPs) if they can adversely affect human health, including the respiratory tract. HAPs include particulate and gaseous-phase pollutants, individual organic compounds and metals, and mixtures. Associations between asthma exacerbation and both particles and indoor volatile organic compounds (VOCs), often referred to as indoor air quality, have been reported. Studies conducted in the United States, Canada, and Europe over the past two decades have shown that most people living in the developed countries spend the majority of their time indoors and that the air concentrations of many air toxics or HAPs are higher indoors than in the ambient air in urban, suburban, and rural settings. Elevated indoor air concentrations result from emissions of air toxics from consumer products, household furnishings, and personal activities. The Relationship of Indoor, Outdoor and Personal Air (RIOPA) study was designed to oversample homes in close proximity to ambient sources, excluding residences where smokers lived, to determine the contribution of ambient emissions to air toxics exposure. The ratios of indoor to outdoor air concentrations of some VOCs in homes measured during RIOPA were much greater than one, and for most other VOCs that had indoor-to-outdoor ratios close to unity in the majority of homes, elevated ratios were found in the paired samples with the highest concentration. Thus, although ambient emissions contribute to exposure of some air toxics indoors as well as outdoors, this was not true for all of the air toxics and especially for the higher end of exposures to most volatile organic air toxics examined

  3. 1991 EPA/AWMA international symposium on measurement of toxic and related air pollutants

    SciTech Connect

    Gay, B.W. Jr.

    1991-01-01

    The purpose of this symposium was to provide a forum for exchange of information on the measurement of toxic and related air pollutants. The conference included presentations on the following: ozone precursors; atmospheric chemistry and fate of toxic pollutants; measurement of particulates and acidic aerosols; cloud water chemistry; asbestos exposure assessment; Staten Island/NJ Urban Air Toxics Assessment Project; personal exposure monitors; mobile sources emissions characterization; VOC monitoring for Clean Air Act Amendment requirement; product emission measurement in test chambers; USA/USSR joint air pollution study; VOC monitoring techniques; measurement of VOCs; measurement of polar volatile organics; exposure assessment; remote sensing for emissions monitoring; measurement methods development; measurement of hazardous waste emissions; chemometrics and environmental data analysis; source monitoring; air pollution dispersion modeling; measurement and data analysis of indoor toxic air contaminants; and environmental quality assurance. Two hundred seventeen papers have been processed separately for inclusion in the appropriate data bases.

  4. Tropospheric gas at potentially toxic levels in air

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Atreyee

    2012-08-01

    Forest fires and emission of air pollutants, such as fumes from vehicles running on diesel and slow burning of coal and charcoal, release isocyanic acid in the troposphere. In 2011, scientists first detected isocyanic acid in the ambient atmosphere at levels toxic to human populations; at concentrations exceeding 1 part per billion by volume (ppbv), human beings could experience tissue decay when exposed to the toxin. For the first time, using a chemical transport model designed to estimate the distribution and budget of isocyanic acid in the troposphere, Young et al. showed that in several parts of the world, local emissions may increase the concentration of isocyanic acid in the ambient atmosphere, thereby exposing large populations to potentially toxic levels of the acid.

  5. QUANTIFYING SUBGRID POLLUTANT VARIABILITY IN EULERIAN AIR QUALITY MODELS

    EPA Science Inventory

    In order to properly assess human risk due to exposure to hazardous air pollutants or air toxics, detailed information is needed on the location and magnitude of ambient air toxic concentrations. Regional scale Eulerian air quality models are typically limited to relatively coar...

  6. INEEL AIR MODELING PROTOCOL ext

    SciTech Connect

    C. S. Staley; M. L. Abbott; P. D. Ritter

    2004-12-01

    Various laws stemming from the Clean Air Act of 1970 and the Clean Air Act amendments of 1990 require air emissions modeling. Modeling is used to ensure that air emissions from new projects and from modifications to existing facilities do not exceed certain standards. For radionuclides, any new airborne release must be modeled to show that downwind receptors do not receive exposures exceeding the dose limits and to determine the requirements for emissions monitoring. For criteria and toxic pollutants, emissions usually must first exceed threshold values before modeling of downwind concentrations is required. This document was prepared to provide guidance for performing environmental compliance-driven air modeling of emissions from Idaho National Engineering and Environmental Laboratory facilities. This document assumes that the user has experience in air modeling and dose and risk assessment. It is not intended to be a "cookbook," nor should all recommendations herein be construed as requirements. However, there are certain procedures that are required by law, and these are pointed out. It is also important to understand that air emissions modeling is a constantly evolving process. This document should, therefore, be reviewed periodically and revised as needed. The document is divided into two parts. Part A is the protocol for radiological assessments, and Part B is for nonradiological assessments. This document is an update of and supersedes document INEEL/INT-98-00236, Rev. 0, INEEL Air Modeling Protocol. This updated document incorporates changes in some of the rules, procedures, and air modeling codes that have occurred since the protocol was first published in 1998.

  7. Air toxics and asthma: Impacts and end points

    SciTech Connect

    Eschenbacher, W.L.; Holian, A.; Campion, R.J.

    1995-09-01

    The National Urban Air Toxics Research Center (NUATRC) hosted a medical/scientific workshop (February 1994) focused on possible asthma/air toxics relationships, with the results of the NUATRC`s first research contract with the University of Cincinnati as the point of discussion. The workshop explored the impact of various environmental factors, including air toxics, on asthma incidence and exacerbation; and emphasis was placed on future research directions. The information presented at the workshop suggested a possible association of asthma exacerbations with ozone and particulate matter (PM{sub 10}); however, direct relationships between worsening asthma and air toxic ambient levels were not established. Possible respiratory health effects associated with air toxics will require considerably more investigation, especially in the area of human exposure assessment. Two major recommendations for future research resulted form this workshop and an accompanying NUATRC Scientific Advisory Panel meeting: a need for more complete individual personal exposure assessments so that accurate determinations of actual personal exposures to various pollutants can be made; and a need for field experiments utilizing biomarkers of exposure and effect to more accurately assess the extent and variability of the biological effects, if any, of individual air toxics. 8 refs.

  8. The National Near-Road Mobile Source Air Toxics Study

    EPA Science Inventory

    Recently, much attention has been directed at understanding the impact of mobile sources on near-road air quality, especially PM and its components, NOx and CO, but little information exists for mobile source air toxics (MSATs). MSATs of interest to this project are 1,3-butadiene...

  9. Evolution of the Air Toxics under the Big Sky Program

    ERIC Educational Resources Information Center

    Marra, Nancy; Vanek, Diana; Hester, Carolyn; Holian, Andrij; Ward, Tony; Adams, Earle; Knuth, Randy

    2011-01-01

    As a yearlong exploration of air quality and its relation to respiratory health, the "Air Toxics Under the Big Sky" program offers opportunities for students to learn and apply science process skills through self-designed inquiry-based research projects conducted within their communities. The program follows a systematic scope and sequence…

  10. Air toxics and asthma: impacts and end points.

    PubMed

    Eschenbacher, W L; Holian, A; Campion, R J

    1995-09-01

    The National Urban Air Toxics Research Center (NUATRC) hosted a medical/scientific workshop focused on possible asthma/air toxics relationships, with the results of the NUATRC's first research contract with the University of Cincinnati as the point of discussion. The workshop was held at the Texas Medical Center on 4 February 1994 and featured presentations by distinguished academic, government, and industry scientists. This one-day session explored the impact of various environmental factors, including air toxics, on asthma incidence and exacerbation; an emphasis was placed on future research directions to be pursued in the asthma/air toxics area. A key research presentation on the association of air toxics and asthma, based on the study sponsored by NUATRC, was given by Dr. George Leikauf of the University of Cincinnati Medical Center. Additional presentations were made by H. A. Boushey, Jr., Cardiovascular Research Institute/University of California at San Francisco, who spoke on of the Basic Mechanisms of Asthma; K. Sexton, U.S. Environmental Protection Agency, who spoke on hazardous air pollutants: science/policy interface; and D. V. Bates, Department of Health Care and Epidemiology at the University of British Columbia, who spoke on asthma epidemiology. H. Koren, U.S. Environmental Protection Agency, and M. Yeung, of the Respiratory Division/University of British Columbia, Vancouver General Hospital, discussed occupational health impacts on asthma. Doyle Pendleton, Texas Natural Resource Conservation Commission, reviewed air quality measurements in Texas. The information presented at the workshop suggested a possible association of asthma exacerbations with ozone and particulate matter (PM10); however, direct relationships between worsening asthma and air toxic ambient levels were not established. Possible respiratory health effects associated with air toxics will require considerably more investigation, especially in the area of human exposure assessment

  11. SNRB{trademark} air toxics monitoring. Final report

    SciTech Connect

    Not Available

    1994-01-01

    Babcock & Wilcox (B&W) is currently conducting a project under the DOE`s Clean Coal Technology (CCT II) Program to demonstrate its SO{sub x}NO{sub x}-Rox Box{trademark} (SNRB{trademark}) process in a 5 MWe Field Demonstration Unit at Ohio Edison`s R. E. Burger Plant near Shadyside, Ohio. The objective of the SNRB{trademark} Air Toxics Monitoring Project was to provide data on SNRB{trademark} air toxics emissions control performance to B&W and to add to the DOE/EPRI/EPA data base by quantifying the flow rates of selected hazardous substances (or air toxics) in all of the major input and output streams of the SNRB{trademark} process as well as the power plant. Work under the project included the collection and analysis of representative samples of all major input and output streams of the SNRB{trademark} demonstration unit and the power plant, and the subsequent laboratory analysis of these samples to determine the partitioning of the hazardous substances between the various process streams. Material balances for selected air toxics were subsequently calculated around the SNRB{trademark} and host boiler systems, including the removal efficiencies across each of the major air pollution control devices. This report presents results of the SNRB{trademark} Air Toxics Monitoring Project. In addition to the Introduction, a brief description of the test site, including the Boiler No. 8 and the SNRB{trademark} process, is included in Section H. The concentrations of air toxic emissions are presented in Section II according to compound class. Material balances are included in Section IV for three major systems: boiler, electrostatic precipitator, and SNRB{trademark}. Emission factors and removal efficiencies are also presented according to compound class in Sections V and VI, respectively. A data evaluation is provided in Section VII.

  12. Advanced combustor design concept to control NOx and air toxics

    SciTech Connect

    Eddings, E.G.; Pershing, D.W.; Molina, A.; Sarofim, A.F.; Spinti, J.P.; Veranth, J.

    1999-03-29

    Direct coal combustion needs to be a primary energy source for the electric utility industry and for heavy manufacturing during the next several decades because of the availability and economic advantage of coal relative to other fuels and because of the time required to produce major market penetration in the energy field. However, the major obstacle to coal utilization is a set of ever-tightening environmental regulations at both the federal and local level. It is, therefore, critical that fundamental research be conducted to support the development of low-emission, high-efficiency pulverized coal power systems. The objective of this program was to develop fundamental understanding regarding the impact of fuel and combustion changes on NOx formation, carbon burnout and air toxic emissions from pulverized coal (pc) combustion. During pc combustion, nitrogen in the coal can be oxidized to form nitrogen oxides (NO{sub x}). The 1990 Clean Air Act Amendments established much stricter NO{sub x} emissions limits for new and existing coal-fired plants, so there has been renewed interest in the processes by which NO{sub x} forms in pc flames. One of the least understood aspects of NO{sub x} formation from pc combustion is the process by which char-N (nitrogen remaining in the char after devolatilization) forms either NO{sub x} or N{sub 2}, and the development of a fundamental understanding of this process was a major focus of this research. The overall objective of this program was to improve the ability of combustion system designers and boiler manufacturers to build high efficiency, low emission pulverized coal systems by improving the design tools available to the industry. The specific program goals were to: Use laboratory experiments and modeling to develop fundamental understanding for a new submodel for char nitrogen oxidation (a critical piece usually neglected in most NOx models.); Use existing bench scale facilities to investigate alternative schemes to

  13. Integrating the federal and California air toxics programs

    SciTech Connect

    Fletcher, R.D.

    1996-12-31

    This paper discusses California`s existing air toxic program and presents an approach for integrating the program with the federal program. Competitiveness can be enhanced by a strong federal program, but a smooth integration is essential to maintain an effective state program. Flexibility and good communication are essential to ensure a smooth integration and successful implementation.

  14. AIR TOXICS EMISSIONS FROM A VINYL SHOWER CURTAIN

    EPA Science Inventory

    The paper reports results of both static and dynamic chamber tests conducted to evaluate emission characteristics of air toxics from a vinyl shower Curtain. (NOTE: Due to the relatively low price and ease of installation, vinyl shower curtains have been widely used in bathrooms i...

  15. Uneven Magnitude of Disparities in Cancer Risks from Air Toxics

    PubMed Central

    James, Wesley; Jia, Chunrong; Kedia, Satish

    2012-01-01

    This study examines race- and income-based disparities in cancer risks from air toxics in Cancer Alley, LA, USA. Risk estimates were obtained from the 2005 National Air Toxics Assessment and socioeconomic and race data from the 2005 American Community Survey, both at the census tract level. Disparities were assessed using spatially weighted ordinary least squares (OLS) regression and quantile regression (QR) for five major air toxics, each with cancer risk greater than 10−6. Spatial OLS results showed that disparities in cancer risks were significant: People in low-income tracts bore a cumulative risk 12% more than those in high-income tracts (p < 0.05), and those in black-dominant areas 16% more than in white-dominant areas (p < 0.01). Formaldehyde and benzene were the two largest contributors to the disparities. Contributions from emission sources to disparities varied by compound. Spatial QR analyses showed that magnitude of disparity became larger at the high end of exposure range, indicating worsened disparity in the poorest and most highly concentrated black areas. Cancer risk of air toxics not only disproportionately affects socioeconomically disadvantaged and racial minority communities, but there is a gradient effect within these groups with poorer and higher minority concentrated segments being more affected than their counterparts. Risk reduction strategies should target emission sources, risk driver chemicals, and especially the disadvantaged neighborhoods. PMID:23208297

  16. Methods for determination of toxic organic compounds in air

    SciTech Connect

    Winberry, W.T. Jr.

    1990-01-01

    This paper provides environmental regulatory agencies, industry, and other interested parties with specific, standardized sampling and analysis procedures for toxic organic compounds in air. Compounds include Volatile Organic Compounds, Organochlorine Pesticides and PCBs, Aldehydes and Ketones, Phosgene, N-Nitrosodimethylamine, Phenol and Methylphenols (Cresols), Polychlorinated Dibenzo-p-Dioxins (PCDDs), Formaldehyde, Non-Methane Organic Compounds (NMOCs) and Polynuclear Aromatic Hydrocarbons (PAHs).

  17. Measurement of air toxics using extractive FTIR spectroscopy

    SciTech Connect

    Lacoss, J.P.; Ogle, L.D.; Shareef, G.S.

    1995-12-31

    In response to the 1990 Clean Air Act Amendments, the Gas Research Institute (GRI) is investigating air toxics emissions from natural gas industry sources. Included in this effort are measurements from internal combustion engines, one of the source categories targeted by U.S. Environmental Protection Agency (EPA) for development of maximum achievable control technology (MACT) based regulations by the year 2000. Formaldehyde and other aldehydes are the air toxics potentially present in engine exhaust. Since there are no EPA approved methods available for quantifying aldehydes in engine exhaust, GRI initiated a field test to validate an extractive Fourier transform infrared spectroscopy (FTIR) based method according to U.S. EPA Method 301 {open_quotes}Field Validation of Pollutant Measurement Methods for Various Media{close_quotes}. The extended paper presents the results of this validation testing for formaldehyde, acetaldehyde, and acrolein conducted to support this validation testing.

  18. AIR Model Preflight Analysis

    NASA Technical Reports Server (NTRS)

    Tai, H.; Wilson, J. W.; Maiden, D. L.

    2003-01-01

    The atmospheric ionizing radiation (AIR) ER-2 preflight analysis, one of the first attempts to obtain a relatively complete measurement set of the high-altitude radiation level environment, is described in this paper. The primary thrust is to characterize the atmospheric radiation and to define dose levels at high-altitude flight. A secondary thrust is to develop and validate dosimetric techniques and monitoring devices for protecting aircrews. With a few chosen routes, we can measure the experimental results and validate the AIR model predictions. Eventually, as more measurements are made, we gain more understanding about the hazardous radiation environment and acquire more confidence in the prediction models.

  19. An empirical analysis of exposure-based regulation to abate toxic air pollution

    SciTech Connect

    Marakovits, D.M.; Considine, T.J.

    1996-11-01

    Title III of the 1990 Clean Air Act Amendments requires the Environmental Protection Agency to regulate 189 air toxics, including emissions from by-product coke ovens. Economists criticize the inefficiency of uniform standards, but Title III makes no provision for flexible regulatory instruments. Environmental health scientists suggest that population exposure, not necessarily ambient air quality, should motivate environmental air pollution policies. Using an engineering-economic model of the United States steel industry, we estimate that an exposure-based policy can achieve the same level of public health as coke oven emissions standards and can reduce compliance costs by up to 60.0%. 18 refs., 3 figs., 1 tab.

  20. Toxic air contaminants in urban atmospheres: Experience in California

    NASA Astrophysics Data System (ADS)

    Seiber, James N.

    In addition to the criteria gaseous and particulate air pollutants which have been the subject of intensive regulation for many years in the U.S., there exists in the atmosphere of cities and surrounding areas a number of trace toxic contaminants which are of increasing public health and regulatory concern. In California, these Toxic Air Contaminants (TACs) are assessed and regulated by a multi-step process required by legislation. Risk assessment for chemicals which are considered potential TACs involves the gathering and analysis of information on emissions, exposures, toxicology, and epidemiology by two California Agencies, the Air Resources Board and Department of Health Services (now linked by the California Environmental Protection Agency) and an independent Scientific Review Panel. Eighteen chemicals have been designated as TACs since the process started in 1982, including perchloroethylene, formaldehyde, vinyl chloride, and 1,3-butadiene which are mentioned in some detail in this review. Future challenges for risk assessment and management are posed by such issues as gross mixtures, for example, from products of incomplete combustion; transport and deposition out of the originating air basin; contributions of natural sources to ambient levels; and the impact of the list of 189 hazardous air pollutants in the 1990 U.S. Clean Air Act Amendments on California's TAC identification-regulation process. The issues involved in a vigorous pursuit of risk reduction from TACs are discussed based upon experience in California.

  1. Mobile Source Air Toxics Rule (released in AEO2008)

    EIA Publications

    2008-01-01

    On February 9, 2007, the Environmental Protection Agency (EPA) released its MSAT2 rule, which will establish controls on gasoline, passenger vehicles, and portable fuel containers. The controls are designed to reduce emissions of benzene and other hazardous air pollutants. Benzene is a known carcinogen, and the EPA estimates that mobile sources produced more than 70% of all benzene emissions in 1999. Other mobile source air toxics, including 1,3-butadiene, formaldehyde, acetaldehyde, acrolein, and naphthalene, also are thought to increase cancer rates or contribute to other serious health problems.

  2. Air toxics risk standards: are we addressing the real problems?

    SciTech Connect

    Laurie Miller; Richard Becker; Ted Cromwell

    2005-06-01

    Cost-effective risk reductions from major stationary emission sources have seen significant progress. EPA and state data demonstrate that their programs have dramatically reduced emissions and risk from these sources. Analyses indicate that the next generation of risk reductions for stationary sources will be provide little risk reduction, but will be much more costly and more challenging from a policy perspective. Facing these tough choices, EPA and state regulators should, with stakeholder input, be developing scientifically driven and cost-effective approaches to provide the public with honest answers and results. Air toxics risk policies and programs must prioritize and address significant remaining air toxics risks, educate and communicate to the public about the decision alternatives, build support for a holistic approach and openly communicate results. 6 refs.

  3. Air toxics emissions from gas-fired engines

    SciTech Connect

    Meeks, H.N. Jr. )

    1992-07-01

    In 1190, 14 natural-gas-fired internal combustion engines (ICE's) in oilfield service were tested in Santa Barbara County, CA, to satisfy California air toxics legislation. The combustion exhaust was tested for formaldehyde, acetaldehyde, acrolein, benzene, toluene, xylences, naphthalene, and polycyclic aromatic hydrocarbons. The fuel was tested for aromatics to enable calculation of destruction efficiencies. Two-stroke and four-stroke engines were tested. Four-stroke engines ranging from 39 to 208 hp were used in pumping unit and constant load service. Emissions from four-stroke engines were unrelated to size and service. The two-stroke engines produced considerably higher emissions than the four-stroke engines. This paper reports that test results indicate natural-gas-fired ICE's produce toxic substances in small amounts. Formaldehyde and benzene dominated the toxic emission profile.

  4. Evaluating the Spatial Distribution of Toxic Air Contaminants in Multiple Ecosystem Indicators in the Sierra Nevada-Southern Cascades

    NASA Astrophysics Data System (ADS)

    Nanus, L.; Simonich, S. L.; Rocchio, J.; Flanagan, C.

    2013-12-01

    Toxic air contaminants originating from agricultural areas of the Central Valley in California threaten vulnerable sensitive receptors including surface water, vegetation, snow, sediments, fish, and amphibians in the Sierra Nevada-Southern Cascades region. The spatial distribution of toxic air contaminants in different ecosystem indicators depends on variation in atmospheric concentrations and deposition, and variation in air toxics accumulation in ecosystems. The spatial distribution of organic air toxics and mercury at over 330 unique sampling locations and sample types over two decades (1990-2009) in the Sierra Nevada-Southern Cascades region were compiled and maps were developed to further understand spatial patterns and linkages between air toxics deposition and ecological effects. Potential ecosystem impacts in the Sierra Nevada-Southern Cascades region include bioaccumulation of air toxics in both aquatic and terrestrial ecosystems, reproductive disruption, and immune suppression. The most sensitive ecological end points in the region that are affected by bioaccumulation of toxic air contaminants are fish. Mercury was detected in all fish and approximately 6% exceeded human consumption thresholds. Organic air toxics were also detected in fish yielding variable spatial patterns. For amphibians, which are sensitive to pesticide exposure and potential immune suppression, increasing trends in current and historic use pesticides are observed from north to south across the region. In other indicators, such as vegetation, pesticide concentrations in lichen increase with increasing elevation. Current and historic use pesticides and mercury were also observed in snowpack at high elevations in the study area. This study shows spatial patterns in toxic air contaminants, evaluates associated risks to sensitive receptors, and identifies data gaps. Future research on atmospheric modeling and information on sources is needed in order to predict which ecosystems are the

  5. Toxicity of Silver Nanoparticles at the Air-Liquid Interface

    PubMed Central

    Holder, Amara L.; Marr, Linsey C.

    2013-01-01

    Silver nanoparticles are one of the most prevalent nanomaterials in consumer products. Some of these products are likely to be aerosolized, making silver nanoparticles a high priority for inhalation toxicity assessment. To study the inhalation toxicity of silver nanoparticles, we have exposed cultured lung cells to them at the air-liquid interface. Cells were exposed to suspensions of silver or nickel oxide (positive control) nanoparticles at concentrations of 2.6, 6.6, and 13.2 μg cm−2 (volume concentrations of 10, 25, and 50 μg ml−1) and to 0.7 μg cm−2 silver or 2.1 μg cm−2 nickel oxide aerosol at the air-liquid interface. Unlike a number of in vitro studies employing suspensions of silver nanoparticles, which have shown strong toxic effects, both suspensions and aerosolized nanoparticles caused negligible cytotoxicity and only a mild inflammatory response, in agreement with animal exposures. Additionally, we have developed a novel method using a differential mobility analyzer to select aerosolized nanoparticles of a single diameter to assess the size-dependent toxicity of silver nanoparticles. PMID:23484109

  6. Concentrations of air toxics in motor vehicle-dominated environments.

    PubMed

    Fujita, Eric M; Campbell, David E; Zielinska, Barbara; Arnott, William P; Chow, Judith C

    2011-02-01

    We at the Desert Research Institute (DRI*) measured volatile organic compounds (VOCs), including several mobile-source air toxics (MSATs), particulate matter with a mass mean aerodynamic diameter < or = 2.5 pm (PM2.5), black carbon (BC), nitrogen oxides (NOx), particulate matter (PM), and carbon monoxide (CO) on highways in Los Angeles County during summer and fall 2004, to characterize the diurnal and seasonal variations in measured concentrations related to volume and mix of traffic. Concentrations of on-road pollutants were then compared to corresponding measurements at fixed monitoring sites. The on-road concentrations of CO and MSATs were higher in the morning under stable atmospheric conditions and during periods of higher traffic volumes. In contrast, BC concentrations, measured as particulate light absorption, were higher on truck routes during the midday sampling periods despite more unstable atmospheric conditions. Compared to the measurements at the three near-road sites, the 1-hour averages of on-road BC concentrations were as much as an order of magnitude higher. The peak 1-minute average concentrations were two orders of magnitude higher for BC and were between two and six times higher for PM2.5 mass. The on-road concentrations of benzene, toluene, ethylbenzene, and xylenes (BTEX) during the summer were 3.5 +/- 0.7 and 1.2 +/- 0.6 times higher during morning and afternoon commuting periods, respectively, compared to annual average 24-hour concentrations measured at air toxic monitoring network sites. These ratios were higher during the fall, with smaller diurnal differences (4.8 +/- 0.7 and 3.9 +/- 0.6 for morning and afternoon commuting periods, respectively). Ratios similar to those for BTEX were obtained for 1,3-butadiene (BD) and styrene. On-road concentrations of formaldehyde and acetaldehyde were up to two times higher than at air toxics monitoring sites, with fall ratios slightly higher than summer ratios. Chemical mass balance (CMB) receptor

  7. Characterizing Air Toxics from Oil Field Operations in Los Angeles

    NASA Astrophysics Data System (ADS)

    McCarthy, M. C.; Brown, S. G.; DeWinter, J. L.; Bai, S.; O'Brien, T.; Vaughn, D.; Peltier, R.; Soltis, J.; Field, R. A.; Murphy, S. M.; Roberts, P. T.

    2014-12-01

    The Inglewood Oil Field in urban Los Angeles has been in operation for more than 70 years. Neighborhoods surrounding the oil field are concerned with the potential emissions of air toxics from oil field operations. The Baldwin Hills Air Quality Study focused on (1) quantifying air toxics concentrations originating from the Inglewood Oil Field operations, including drilling and well workovers, and (2) assessing the health risk of both acute and chronic exposure to air toxics emitted from oil field operations. Key pollutants identified for characterization included diesel particulate matter (DPM), cadmium, benzene, nickel, formaldehyde, mercury, manganese, acrolein, arsenic, and lead. The field study began in November 2012 and ended in November 2013. Four types of instruments were used to characterize oil field operations: (1) Aethalometers to measure black carbon (BC; as a proxy for DPM); (2) X-ray fluorescence spectrometer (XRF) for metals; (3) Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-TOFMS) for volatile organic compounds; and (4) meteorological sensors to help assess the wind patterns, temperature, and humidity that influence pollutant concentrations. Overall concentrations of most of the species measured in the study were quite low for an urban area. We determined that there were statistically significant increases in concentrations of DPM associated with oil field operations when winds were from the west-southwest. BC concentrations increased by 0.036 to 0.056 μg/m3, on average, when winds originated from the west-southwest, compared to annual mean BC concentrations of approximately 0.67 μg/m3. West-southwest winds occurred 53% of the time during the study. No other pollutants showed strong statistical evidence of chronic or acute risk from oil field operations.

  8. Air toxic emissions from snowmobiles in Yellowstone National Park.

    PubMed

    Zhou, Yong; Shively, David; Mao, Huiting; Russo, Rachel S; Pape, Bruce; Mower, Richard N; Talbot, Robert; Sive, Barkley C

    2010-01-01

    A study on emissions associated with oversnow travel in Yellowstone National Park (YNP) was conducted for the time period of February 13-16, 2002 and February 12-16, 2003. Whole air and exhaust samples were characterized for 85 volatile organic compounds using gas chromatography. The toxics including benzene, toluene, ethylbenzene, xylenes (p-, m-, and o-xylene), and n-hexane, which are major components of two-stroke engine exhaust, show large enhancements during sampling periods resulting from increased snowmobile traffic. Evaluation of the photochemical history of air masses sampled in YNP revealed that emissions of these air toxics were (i) recent, (ii) persistent throughout the region, and (iii) consistent with the two-stroke engine exhaust sample fingerprints. The annual fluxes were estimated to be 0.35, 1.12, 0.24, 1.45, and 0.36 Gg yr(-1) for benzene, toluene, ethylbenzene, xylenes, and n-hexane, respectively, from snowmobile usage in YNP. These results are comparable to the flux estimates of 0.23, 0.77, 0.17, and 0.70 Gg yr(-1) for benzene, toluene, ethylbenzene, and xylenes, respectively, that were derived on the basis of (i) actual snowmobile counts in the Park and (ii) our ambient measurements conducted in 2003. Extrapolating these results, annual emissions from snowmobiles in the U.S. appear to be significantly higher than the values from the EPA National Emissions Inventory (1999). Snowmobile emissions represent a significant fraction ( approximately 14-21%) of air toxics with respect to EPA estimates of emissions by nonroad vehicles. Further investigation is warranted to more rigorously quantify the difference between our estimates and emission inventories.

  9. Air toxics evaluation of ABB Combustion Engineering Low-Emission Boiler Systems

    SciTech Connect

    Wesnor, J.D.

    1993-10-26

    The specific goals of the program are to identify air toxic compounds that might be emmitted from the new boiler with its various Air Pollution Control device for APCD alternatives in levels of regulatory concern. For the compounds thought to be of concern, potential air toxic control methodologies will be suggested and a Test Protocol will be written to be used in the Proof of Concept and full scale tests. The following task was defined: Define Replations and Standards; Identify Air Toxic Pollutants of Interest to Interest to Utility Boilers; Assesment of Air Toxic By-Products; State of the Art Assessment of Toxic By-Product Control Technologies; and Test Protocol Definition.

  10. Predictive Modeling of Developmental Toxicity

    EPA Science Inventory

    The use of alternative methods in conjunction with traditional in vivo developmental toxicity testing has the potential to (1) reduce cost and increase throughput of testing the chemical universe, (2) prioritize chemicals for further targeted toxicity testing and risk assessment,...

  11. [Toxic fungi in Buenos Aires City and surroundings].

    PubMed

    Romano, Gonzalo M; Iannone, Leopoldo; Novas, María V; Carmarán, Cecilia; Romero, Andrea I; López, Silvia E; Lechner, Bernardo E

    2013-01-01

    In Facultad de Ciencias Exactas y Naturales,Universidad de Buenos Aires there is a service called Servicio de Identificación de Hongos Tóxicos, directed by researchers of the Program of Medicinal Plants and Fungi Involved in Biological Degradation (PROPLAME-PRHIDEB, CONICET) that assist hospitals and other health establishments, identifying the different samples of fungi and providing information about their toxicity, so that patients can receive the correct treatment. The objective of the present study was to analyze all the cases received from 1985 to 2012. This analysis permitted the confection of a table identifying the most common toxic species. The information gathered revealed that 47% of the patients were under 18 years of age and had eaten basidiomes; the remaining 53% were adults who insisted that they were able to distinguish edible from toxic mushrooms. Chlorophyllum molybdites turned out to be the main cause of fungal intoxication in Buenos Aires, which is commonly confused with Macrolepiota procera, an edible mushroom. In the second place Amanita phalloides was registered, an agaric known to cause severe symptoms after a long period of latency (6-10 hours), and which can lead to hepatic failure even requiring a transplant to prevent severe internal injuries or even death, is not early and correctly treated.

  12. [Toxic fungi in Buenos Aires City and surroundings].

    PubMed

    Romano, Gonzalo M; Iannone, Leopoldo; Novas, María V; Carmarán, Cecilia; Romero, Andrea I; López, Silvia E; Lechner, Bernardo E

    2013-01-01

    In Facultad de Ciencias Exactas y Naturales,Universidad de Buenos Aires there is a service called Servicio de Identificación de Hongos Tóxicos, directed by researchers of the Program of Medicinal Plants and Fungi Involved in Biological Degradation (PROPLAME-PRHIDEB, CONICET) that assist hospitals and other health establishments, identifying the different samples of fungi and providing information about their toxicity, so that patients can receive the correct treatment. The objective of the present study was to analyze all the cases received from 1985 to 2012. This analysis permitted the confection of a table identifying the most common toxic species. The information gathered revealed that 47% of the patients were under 18 years of age and had eaten basidiomes; the remaining 53% were adults who insisted that they were able to distinguish edible from toxic mushrooms. Chlorophyllum molybdites turned out to be the main cause of fungal intoxication in Buenos Aires, which is commonly confused with Macrolepiota procera, an edible mushroom. In the second place Amanita phalloides was registered, an agaric known to cause severe symptoms after a long period of latency (6-10 hours), and which can lead to hepatic failure even requiring a transplant to prevent severe internal injuries or even death, is not early and correctly treated. PMID:24152394

  13. PETROTOX: an aquatic toxicity model for petroleum substances.

    PubMed

    Redman, Aaron D; Parkerton, Thomas F; McGrath, Joy A; Di Toro, Dominic M

    2012-11-01

    A spreadsheet model (PETROTOX) is described that predicts the aquatic toxicity of complex petroleum substances from petroleum substance composition. Substance composition is characterized by specifying mass fractions in constituent hydrocarbon blocks (HBs) based on available analytical information. The HBs are defined by their mass fractions within a defined carbon number range or boiling point interval. Physicochemical properties of the HBs are approximated by assigning representative hydrocarbons from a database of individual hydrocarbons with associated physicochemical properties. A three-phase fate model is used to simulate the distribution of each structure among the water-, air-, and oil-phase liquid in the laboratory test system. Toxicity is then computed based on the predicted aqueous concentrations and aquatic toxicity of each structure and the target lipid model. The toxicity of the complex substance is computed assuming additivity of the contribution of the individual assigned hydrocarbons. Model performance was evaluated by using direct comparisons with measured toxicity data for petroleum substances with sufficient analytical characterization to run the model. Indirect evaluations were made by comparing predicted toxicity distributions using analytical data on petroleum substances from different product categories with independent, empirical distributions of toxicity data available for the same categories. Predictions compared favorably with measured aquatic toxicity data across different petroleum substance categories. These findings demonstrate the utility of PETROTOX for assessing environmental hazards of petroleum substances given knowledge of substance composition.

  14. Addressing community concerns about asthma and air toxics.

    PubMed Central

    White, Mary C; Berger-Frank, Sherri A; Middleton, Dannie C; Falk, Henry

    2002-01-01

    People with asthma who live near or downwind from a source of toxic emissions commonly express concerns about the possible impact of hazardous air pollution on their health, especially when these emissions are visible or odorous. Citizens frequently turn to their local and state health departments for answers, but health departments face many challenges in addressing these concerns. These challenges include a lack of asthma statistics at the local level, limited exposure information, and a paucity of scientific knowledge about the contributions of hazardous air pollutants to asthma induction or exacerbation. Health agencies are creatively developing methods to address these challenges while working toward improving asthma surveillance data at the state and local levels. Recent community health investigations suggest that hazardous air pollutants that are occupational asthmagens or associated with odors may deserve more attention. In seeking to address community concerns about hazardous air pollution and asthma, community health investigations may also help to fill gaps in our scientific knowledge and identify areas for further research or environmental intervention. The solutions to community problems associated with environmental contamination and asthma, however, require sustained, coordinated efforts by public and private groups and citizens. Public health agencies can make a unique contribution to this effort, but additional resources and support will be required to develop information systems and epidemiologic capacity at the state and local levels. PMID:12194887

  15. An Evaluation of EPA's National-Scale Air Toxics Assessment (NATA): Comparison with Benzene Measurements in Detroit, Michigan

    EPA Science Inventory

    The U.S. EPA periodically evaluates ambient concentrations, human exposures, and health risks for 180 hazardous air pollutants plus diesel particulate matter using modeled estimates from the National-Scale Air Toxics Assessment (NATA). NATA publishes estimates at the spatial reso...

  16. Quantitative Predictive Models for Systemic Toxicity (SOT)

    EPA Science Inventory

    Models to identify systemic and specific target organ toxicity were developed to help transition the field of toxicology towards computational models. By leveraging multiple data sources to incorporate read-across and machine learning approaches, a quantitative model of systemic ...

  17. Segregation and black/white differences in exposure to air toxics in 1990.

    PubMed Central

    Lopez, Russ

    2002-01-01

    I examined non-Hispanic Black and non-Hispanic White differences in exposure to noncriteria air pollutants in 44 U.S. Census Bureau-defined metropolitan areas with populations greater than one million, using data on air toxics concentrations prepared for the U.S. Environmental Protection Agency as part of its Cumulative Exposure Project combined with U.S. census data. I measured differences in exposure to air toxics through the calculation of a net difference score, which is a statistical measure used in income inequality analysis to measure inequality over the whole range of exposures. The scores ranged from 11.52 to 83.60. In every metropolitan area, non-Hispanic Blacks are more likely than non-Hispanic Whites to be living in tracts with higher total modeled air toxics concentrations. To assess potential reasons for such a wide variation in exposure differences, I performed a multiple regression analysis with the net difference score as the dependent variable. Independent variables initially included were as follows: the dissimilarity index (to measure segregation), Black poverty/White poverty (to control for Black/White economic differences), population density and percentage of persons traveling to work who drive to work (alone and in car pools), and percentage of workforce employed in manufacturing (factors affecting air quality). After an initial analysis I eliminated from the model the measures of density and the persons driving to work because they were statistically insignificant, they did not add to the predictive power of the model, and their deletion did not affect the other variables. The final model had an R(2) of 0.56. Increased segregation is associated with increased disparity in potential exposure to air pollution. PMID:11929740

  18. SIMULATING URBAN AIR TOXICS OVER CONTINENTAL AND URBAN SCALES

    EPA Science Inventory

    The US EPA is evaluating a version of the CMAQ model to support risk assessment for the exposure to Hazardous Air Pollutants (HAPs). The model uses a variant of the CB4 chemical mechanism to simulate ambient concentrations of twenty HAPs that exist primarily as gaseous compounds...

  19. Air modeling: Air dispersion models; regulatory applications and technological advances

    SciTech Connect

    Miller, M.; Liles, R.

    1995-09-01

    Air dispersion models are a useful and practical tool for both industry and regulatory agencies. They serve as tools for engineering, permitting, and regulations development. Their cost effectiveness and ease of implementation compared to ambient monitoring is perhaps their most-appealing trait. Based on the current momentum within the U.S. EPA to develop better models and contain regulatory burdens on industry, it is likely that air dispersion modeling will be a major player in future air regulatory initiatives.

  20. Emissions of air toxics from coal-fired boilers: Arsenic

    SciTech Connect

    Mendelsohn, M.H.; Huang, H.S.; Livengood, C.D.

    1994-08-01

    Concerns over emissions of hazardous air pollutants (air toxics) have emerged as a major environmental issue; the authority of the US Environmental Protection Agency to regulate such pollutants has been greatly expanded through passage of the Clean Air Act Amendments of 1990. Arsenic and arsenic compounds are of concern mainly because of their generally recognized toxicity. Arsenic is also regarded as one of the trace elements in coal subject to significant vaporization. This report summarizes and evaluates available published information on the arsenic content of coals mined in the United States, on arsenic emitted in coal combustion, and on the efficacy of various environmental control technologies for controlling airborne emissions. Bituminous and lignite coals have the highest mean arsenic concentrations, with subbituminous and anthracite coals having the lowest. However, all coal types show very significant variations in arsenic concentrations. Arsenic emissions from coal combustion are not well-characterized, particularly with regard to determination of specific arsenic compounds. Variations in emission, rates of more than an order of magnitude have been reported for some boiler types. Data on the capture of arsenic by environmental control technologies are available primarily for systems with cold electrostatic precipitators, where removals of approximately 50 to 98% have been reported. Limited data for wet flue-gas-desulfurization systems show widely varying removals of from 6 to 97%. On the other hand, waste incineration plants report removals in a narrow range of from 95 to 99%. This report briefly reviews several areas of research that may lead to improvements in arsenic control for existing flue-gas-cleanup technologies and summarizes the status of analytical techniques for measuring arsenic emissions from combustion sources.

  1. 3 CFR - Flexible Implementation of the Mercury and Air Toxics Standards Rule

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 3 The President 1 2012-01-01 2012-01-01 false Flexible Implementation of the Mercury and Air... Flexible Implementation of the Mercury and Air Toxics Standards Rule Memorandum for the Administrator of... the final Mercury and Air Toxics Standards rule for power plants (the “MATS Rule”) represents a...

  2. Optimizing electric utility air toxics compliance with other titles of the Clean Air Act

    SciTech Connect

    Loeb, A.P.; South, D.W.

    1993-12-31

    This paper provides an overview of regulatory issues under Title III of the Clean Air Act Amendments that could affect electric utilities. Title III contains provisions relating to hazardous air pollutants (HAPs) and provides special treatment for electric utilities. Generally, this discussion documents that if utility toxic emissions are regulated, one of the chief difficulties confronting utilities will be the lack of coordination between Title III and other titles of the Act. The paper concludes that if the US Environmental Protection Agency (EPA) determines that regulation of utility HAPs is warranted under Title III, savings can be realized from flexible compliance treatment.

  3. Combinatorial QSAR Modeling of Rat Acute Toxicity by Oral Exposure

    EPA Science Inventory

    Quantitative Structure-Activity Relationship (QSAR) toxicity models have become popular tools for identifying potential toxic compounds and prioritizing candidates for animal toxicity tests. However, few QSAR studies have successfully modeled large, diverse mammalian toxicity end...

  4. Air toxics provisions of the Clean Air Act: Potential impacts on energy

    SciTech Connect

    Hootman, H.A.; Vernet, J.E.

    1991-11-01

    This report provides an overview of the provisions of the Clean Air Act and its Amendments of 1990 that identify hazardous air pollutant (HAP) emissions and addresses their regulation by the US Environmental Protection Agency (EPA). It defines the major energy sector sources of these HAPs that would be affected by the regulations. Attention is focused on regulations that would cover coke oven emissions; chromium emission from industrial cooling towers and the electroplating process; HAP emissions from tank vessels, asbestos-related activities, organic solvent use, and ethylene oxide sterilization; and emissions of air toxics from municipal waste combustors. The possible implications of Title III regulations for the coal, natural gas, petroleum, uranium, and electric utility industries are examined. The report discusses five major databases of HAP emissions: (1) TRI (EPA`s Toxic Release Inventory); (2) PISCES (Power Plant Integrated Systems: Chemical Emissions Studies developed by the Electric Power Research Institute); (3) 1985 Emissions Inventory on volatile organic compounds (used for the National Acid Precipitation Assessment Program); (4) Particulate Matter Species Manual (EPA); and (5) Toxics Emission Inventory (National Aeronautics and Space Administration). It also offers information on emission control technologies for municipal waste combustors.

  5. Air toxics provisions of the Clean Air Act: Potential impacts on energy

    SciTech Connect

    Hootman, H.A.; Vernet, J.E.

    1991-11-01

    This report provides an overview of the provisions of the Clean Air Act and its Amendments of 1990 that identify hazardous air pollutant (HAP) emissions and addresses their regulation by the US Environmental Protection Agency (EPA). It defines the major energy sector sources of these HAPs that would be affected by the regulations. Attention is focused on regulations that would cover coke oven emissions; chromium emission from industrial cooling towers and the electroplating process; HAP emissions from tank vessels, asbestos-related activities, organic solvent use, and ethylene oxide sterilization; and emissions of air toxics from municipal waste combustors. The possible implications of Title III regulations for the coal, natural gas, petroleum, uranium, and electric utility industries are examined. The report discusses five major databases of HAP emissions: (1) TRI (EPA's Toxic Release Inventory); (2) PISCES (Power Plant Integrated Systems: Chemical Emissions Studies developed by the Electric Power Research Institute); (3) 1985 Emissions Inventory on volatile organic compounds (used for the National Acid Precipitation Assessment Program); (4) Particulate Matter Species Manual (EPA); and (5) Toxics Emission Inventory (National Aeronautics and Space Administration). It also offers information on emission control technologies for municipal waste combustors.

  6. Spatial variations of particulate matter and air toxics in communities adjacent to the Port of Oakland.

    PubMed

    Fujita, Eric M; Campbell, David E; Arnott, W Patrick; Lau, Virginia; Martien, Philip T

    2013-12-01

    The Bay Area Air Quality Management District (BAAQMD) sponsored the West Oakland Monitoring Study (WOMS) to provide supplemental air quality monitoring that will be used by the BAAQMD to evaluate local-scale dispersion modeling of diesel emissions and other toxic air contaminants for the area within and around the Port of Oakland. The WOMS was conducted during two seasonal periods of 4 weeks in summer 2009 and winter 2009/2010. Monitoring data showed spatial patterns of pollutant concentrations that were generally consistent with proximity to vehicle traffic. Concentrations of directly emitted pollutants were highest on heavily traveled roads with consistently lower concentrations away from the roadways. Pollutants that have higher emission rates from diesel trucks (nitric oxide, black carbon) tended to exhibit sharper gradients than pollutants that are largely associated with gasoline vehicles, such as carbon monoxide and volatile organic compounds, including benzene, toluene, ethylbenzene, and xylenes (BTEX). BTEX concentrations in West Oakland were similar to those measured at the three air toxics monitoring network sites in the Bay Area (San Francisco, Fremont, and San Jose). Aldehyde levels were higher in Fremont and San Jose than in West Oakland, reflecting greater contributions from photo-oxidation of hydrocarbons downwind of the Bay Area. A 2005 modeling-based health risk assessment of diesel particulate matter concentrations is consistent with aerosol carbon concentrations measured during the WOMS after adjusting for recent mitigation measures and improved estimates of heavy-duty truck traffic volumes.

  7. EMISSIONS OF ORGANIC AIR TOXICS FROM OPEN BURNING: A COMPREHENSIVE REVIEW

    EPA Science Inventory

    A detailed literature search was performed to collect and collate available data reporting emissions of organic air toxics from open burning sources. Availability of data varied according to the source and the class of air toxics of interest, and there were several sources for wh...

  8. Analysis of mobile source air toxics (MSATs)–Near-Road VOC and carbonyl concentrations

    EPA Science Inventory

    Exposures to mobile source air toxics (MSATs) have been associated with numerous adverse health effects. While thousands of air toxic compounds are emitted from mobile sources, a subset of compounds are considered high priority due to their significant contribution to cancer and...

  9. 77 FR 30274 - The Commission's Role Regarding the Environmental Protection Agency's Mercury and Air Toxics...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-22

    .../pkg/FR-2012-02-16/pdf/2012-806.pdf . I. Introduction 2. On December 21, 2011, the EPA released the... Mercury and Air Toxics Standards; Policy Statement on the Commission's Role Regarding the Environmental Protection Agency's Mercury and Air Toxics Standards Before Commissioners: Jon Wellinghoff, Chairman;...

  10. 76 FR 80727 - Flexible Implementation of the Mercury and Air Toxics Standards Rule

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-27

    ... 21, 2011 [FR Doc. 2011-33337 Filed 12-23-11; 8:45 am] Billing code 6560-50-P ... Documents#0;#0; ] Memorandum of December 21, 2011 Flexible Implementation of the Mercury and Air Toxics... the Environmental Protection Agency (EPA), of the final Mercury and Air Toxics Standards rule...

  11. Effect of pyrolysis temperature and air flow on toxicity of gases from a polycarbonate polymer

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Brick, V. E.; Brauer, D. P.

    1978-01-01

    A polycarbonate polymer was evaluated for toxicity of pyrolysis gases generated at various temperatures without forced air flow and with 1 L/min air flow, using the toxicity screening test method developed at the University of San Francisco. Time to various animal responses decreased with increasing pyrolysis temperature over the range from 500 C to 800 C. There appeared to be no significant toxic effects at 400 C and lower temperatures.

  12. Modeling toxic compounds from nitric oxide emission measurements

    NASA Astrophysics Data System (ADS)

    Vallero, Daniel A.; Peirce, Jeffrey; Cho, Ki Don

    Determining the amount and rate of degradation of toxic pollutants in soil and groundwater is difficult and often requires invasive techniques, such as deploying extensive monitoring well networks. Even with these networks, degradation rates across entire systems cannot readily be extrapolated from the samples. When organic compounds are degraded by microbes, especially nitrifying bacteria, oxides or nitrogen (NO x) are released to the atmosphere. Thus, the flux of nitric oxide (NO) from the soil to the lower troposphere can be used to predict the rate at which organic compounds are degraded. By characterizing and applying biogenic and anthropogenic processes in soils the rates of degradation of organic compounds. Toluene was selected as a representative of toxic aromatic compounds, since it is inherently toxic, it is a substituted benzene compound and is listed as a hazardous air pollutant under Section 12 of the Clean Air Act Amendments of 1990. Measured toluene concentrations in soil, microbial population growth and NO fluxes in chamber studies were used to develop and parameterize a numerical model based on carbon and nitrogen cycling. These measurements, in turn, were used as indicators of bioremediation of air toxic (i.e. toluene) concentrations. The model found that chemical concentration, soil microbial abundance, and NO production can be directly related to the experimental results (significant at P < 0.01) for all toluene concentrations tested. This indicates that the model may prove useful in monitoring and predicting the fate of toxic aromatic contaminants in a complex soil system. It may also be useful in predicting the release of ozone precursors, such as changes in reservoirs of hydrocarbons and oxides of nitrogen. As such, the model may be a tool for decision makers in ozone non-attainment areas.

  13. ULTRA HIGH EFFICIENCY ESP DEVELOPMENT FOR AIR TOXICS CONTROL

    SciTech Connect

    David K. Anderson

    1999-11-01

    Because more than 90 percent of U.S. coal-fired utility boilers are equipped with electrostatic precipitators (ESPs), retrofitable ESP technologies represent a logical approach towards achieving the Department of Energy's (DOE) goal of a major reduction in fine particulate and mercury emissions (air toxics) from coal based power systems. EPA's recent issuance of significantly tightened ambient air standards for particles smaller than 2.5 {micro}m (PM{sub 2.5}) creates a new urgency for developing cost-effective means to control fine particulate emissions. This challenge is compounded by the on-going switch in the utility industry to low-sulfur Powder River Basin (PRB) coals, that generate higher resistivity and difficult-to-collect fly ash. Particulate emissions can increase by a factor of ten when a utility switches to a low-sulfur coal. Numerous power plants are presently limited in operation by the inability of their ESPs to control opacity at high loads. In Phase I of this program, ABB investigated five technologies to improve the collection of fine particulate and trace metals in ESPs. These included: (1) flue-gas cooling, (2) flue-gas humidification, (3) pulsed energization, (4) wet ESP and precharger modules, and (5) sorbent injection for mercury control. Tests were conducted with an Eastern bituminous coal and a Powder River Basin sub-bituminous low-sulfur coal in an integrated pilot-scale combustor and ESP test facility. The impacts of the different retrofit technologies on ESP performance, individually and in combination, were evaluated indepth through advanced sampling and measurement techniques. In Phase II, the most promising concepts identified from Phase I testing, flue-gas cooling and humidification, pulsed energization, and sorbent injection at low flue-gas temperatures for mercury control, were integrated into a commercially oriented sub-scale system for field testing at Commonwealth Edison's Waukegan Unit No. 8. The main objective of the proposed

  14. Air Toxics under the Big Sky: A Real-World Investigation to Engage High School Science Students

    ERIC Educational Resources Information Center

    Adams, Earle; Smith, Garon; Ward, Tony J.; Vanek, Diana; Marra, Nancy; Jones, David; Henthorn, Melissa; Striebel, Jim

    2008-01-01

    This paper describes a problem-based chemistry education model in which students perform scientific research on a local environmentally relevant problem. The project is a collaboration among The University of Montana and local high schools centered around Missoula, Montana. "Air Toxics under the Big Sky" involves high school students in collecting…

  15. Consensus Modeling of Oral Rat Acute Toxicity

    EPA Science Inventory

    An acute toxicity dataset (oral rat LD50) with about 7400 compounds was compiled from the ChemIDplus database. This dataset was divided into a modeling set and a prediction set. The compounds in the prediction set were selected so that they were present in the modeling set used...

  16. Evaporation and air-stripping to assess and reduce ethanolamines toxicity in oily wastewater.

    PubMed

    Libralato, G; Ghirardini, A Volpi; Avezzù, F

    2008-05-30

    Toxicity from industrial oily wastewater remains a problem even after conventional activated sludge treatment process, because of the persistence of some toxicant compounds. This work verified the removal efficiency of organic and inorganic pollutants and the effects of evaporation and air-stripping techniques on oily wastewater toxicity reduction. In a lab-scale plant, a vacuum evaporation procedure at three different temperatures and an air-stripping stage were tested on oily wastewater. Toxicity reduction/removal was observed at each treatment step via Microtox bioassay. A case study monitoring real scale evaporation was also done in a full-size wastewater treatment plant (WWTP). To implement part of a general project of toxicity reduction evaluation, additional investigations took into account the monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA) role in toxicity definition after the evaporation phase, both as pure substances and mixtures. Only MEA and TEA appeared to contribute towards effluent toxicity.

  17. A model for field toxicity tests

    USGS Publications Warehouse

    Kaiser, Mark S.; Finger, Susan E.

    1996-01-01

    Toxicity tests conducted under field conditions present an interesting challenge for statistical modelling. In contrast to laboratory tests, the concentrations of potential toxicants are not held constant over the test. In addition, the number and identity of toxicants that belong in a model as explanatory factors are not known and must be determined through a model selection process. We present one model to deal with these needs. This model takes the record of mortalities to form a multinomial distribution in which parameters are modelled as products of conditional daily survival probabilities. These conditional probabilities are in turn modelled as logistic functions of the explanatory factors. The model incorporates lagged values of the explanatory factors to deal with changes in the pattern of mortalities over time. The issue of model selection and assessment is approached through the use of generalized information criteria and power divergence goodness-of-fit tests. These model selection criteria are applied in a cross-validation scheme designed to assess the ability of a model to both fit data used in estimation and predict data deleted from the estimation data set. The example presented demonstrates the need for inclusion of lagged values of the explanatory factors and suggests that penalized likelihood criteria may not provide adequate protection against overparameterized models in model selection.

  18. Avian models for toxicity testing

    USGS Publications Warehouse

    Hill, E.F.; Hoffman, D.J.

    1984-01-01

    The use of birds as test models in experimental and environmental toxicology as related to health effects is reviewed, and an overview of descriptive tests routinely used in wildlife toxicology is provided. Toxicologic research on birds may be applicable to human health both directly by their use as models for mechanistic and descriptive studies and indirectly as monitors of environmental quality. Topics include the use of birds as models for study of teratogenesis and embryotoxicity, neurotoxicity, behavior, trends of environmental pollution, and for use in predictive wildlife toxicology. Uses of domestic and wild-captured birds are discussed.

  19. Case study of municipal air pollution policies: Houston's Air Toxic Control Strategy under the White Administration, 2004-2009.

    PubMed

    Bruhl, Rebecca J; Linder, Stephen H; Sexton, Ken

    2013-05-01

    Local government has traditionally played only a minor role in regulating airborne toxic pollutants. However, from 2004 to 2009, the City of Houston implemented a novel, municipality-based air toxics reduction strategy to address what it considered unacceptable health risks and an insufficient regulatory response from state and federal agencies. The city's effort to exert local control over stationary sources of air toxics represents a unique opportunity to study the selection and performance of policy tools and to consider their ramifications for the design of future air pollution control strategies. The results of this case study demonstrate the potential for municipal government to use a combination of cooperative and confrontational policies to stimulate responses from private industry and state and federal regulators as part of a strategy to address local air quality problems.

  20. Old, the new, the states, the evolution of the regulation of air toxics. Master's thesis

    SciTech Connect

    Vecera, D.R.

    1993-02-14

    The activism associated with America in the 1960s spilled over into many areas, one of which was a new environmental movement. A product of that movement was the Clean Air Act passed in 1970. The new law included a selection aimed specifically at controlling emissions of hazardous or toxic air pollutants. However, over the next 20 years there was very little government regulation of air toxics, and this section of the Clean Air Act was considered to be a resounding failure. What went wrong. How did this lofty goal to protect human health and the environment end up on the back burner. The article will address the idealism that led to the Clean Air Act legislation, in particular the air toxics program, and explore the realities that scuttled those ideals when it came time to implement the law.

  1. MONITORING THE AIR FOR TOXIC AND GENOTOXIC COMPOUNDS

    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 p...

  2. CAAA implementation & legislation combustion strategy, air toxics, etc.

    SciTech Connect

    Segal, S.

    1995-12-31

    Information is presented that deals with the status of the Clean Air Act implementation and legislation; the Republicans and the environment; the status of Superfund legislation in the Senate and the House; the Safe Drinking Water Act reauthorization bill; the Endangered Species Act; Section 112(g) of the Clean Air Act; the Comprehensive Regulatory Reform Act of 1995; and air Pollution.

  3. Biodiesel and Cold Temperature Effect on Speciated Mobile Source Air Toxics from Modern Diesel Trucks

    EPA Science Inventory

    Speciated volatile organic compounds (VOCs) with a particular focus on mobile source air toxics (MSATs) were measured in diesel exhaust from three heavy-duty trucks equipped with modern aftertreatment technologies. Emissions testing was conducted on a temperature controlled chass...

  4. Biodiesel and Cold Temperature Effects on Speciated Mobile Source Air Toxics from Modern Diesel Trucks

    EPA Science Inventory

    Speciated volatile organic compounds (VOCs) with a particular focus on mobile source air toxics (MSATs) were measured in diesel exhaust from three heavy-duty trucks equipped with modern aftertreatment technologies. Emissions testing was conducted on a temperature controlled chass...

  5. Regional Models for Sediment Toxicity Assessment

    EPA Science Inventory

    This paper investigates the use of empirical models to predict the toxicity of sediment samples within a region to laboratory test organisms based on sediment chemistry. In earlier work, we used a large nationwide database of matching sediment chemistry and marine amphipod sedim...

  6. Air-quality-model update

    SciTech Connect

    Penner, J.E.; Walton, J.J.

    1982-01-15

    The Livermore Regional Air Quality Model (LIRAQ) has been updated and improved. This report describes the changes that have been made in chemistry, species treatment, and boundary conditions. The results of smog chamber simulations that were used to verify the chemistry as well as simulations of the entire air quality model for two prototype days in the Bay Area are reported. The results for the prototype day simulations are preliminary due to the need for improvement in meteorology fields, but they show the dependence and sensitivity of high hour ozone to changes in selected boundary and initial conditions.

  7. Reactor modeling in heterogeneous photocatalysis: toxicity and biodegradability assessment.

    PubMed

    Satuf, M L; José, S; Paggi, J C; Brandi, R J; Cassano, A E; Alfano, O M

    2010-01-01

    Photocatalysis employing titanium dioxide is a useful method to degrade a wide variety of organic and inorganic pollutants from water and air. However, the application of this advanced oxidation process at industrial scale requires the development of mathematical models to design and scale-up photocatalytic reactors. In the present work, intrinsic kinetic expressions previously obtained in a laboratory reactor are employed to predict the performance of a bench scale reactor of different configuration and operating conditions. 4-Chlorophenol was chosen as the model pollutant. The toxicity and biodegradability of the irradiated mixture in the bench photoreactor was also assessed. Good agreement was found between simulation and experimental data. The root mean square error of the estimations was 9.9%. The photocatalytic process clearly enhances the biodegradability of the reacting mixture, and the initial toxicity of the pollutant was significantly reduced by the treatment.

  8. Hybrid regional air pollution models

    SciTech Connect

    Drake, R.L.

    1980-03-01

    This discussion deals with a family of air quality models for predicting and analyzing the fine particulate loading in the atmosphere, for assessing the extent and degree of visibility impairment, and for determining the potential of pollutants for increasing the acidity of soils and water. The major horizontal scales of interest are from 400km to 2000km; and the time scales may vary from several hours, to days, weeks, and a few months or years, depending on the EPA regulations being addressed. First the role air quality models play in the general family of atmospheric simulation models is described. Then, the characteristics of a well-designed, comprehensive air quality model are discussed. Following this, the specific objectives of this workshop are outlined, and their modeling implications are summarized. There are significant modeling differences produced by the choice of the coordinate system, whether it be the fixed Eulerian system, the moving Lagrangian system, or some hybrid of the two. These three systems are briefly discussed, and a list of hybrid models that are currently in use are given. Finally, the PNL regional transport model is outlined and a number of research needs are listed.

  9. AIR QUALITY MODELING AT COARSE-TO-FINE SCALES IN URBAN AREAS

    EPA Science Inventory

    Urban air toxics control strategies are moving towards a community based modeling approach, with an emphasis on assessing those areas that experience high air toxic concentration levels, the so-called "hot spots". This approach will require information that accurately maps and...

  10. Air Conditioner Compressor Performance Model

    SciTech Connect

    Lu, Ning; Xie, YuLong; Huang, Zhenyu

    2008-09-05

    During the past three years, the Western Electricity Coordinating Council (WECC) Load Modeling Task Force (LMTF) has led the effort to develop the new modeling approach. As part of this effort, the Bonneville Power Administration (BPA), Southern California Edison (SCE), and Electric Power Research Institute (EPRI) Solutions tested 27 residential air-conditioning units to assess their response to delayed voltage recovery transients. After completing these tests, different modeling approaches were proposed, among them a performance modeling approach that proved to be one of the three favored for its simplicity and ability to recreate different SVR events satisfactorily. Funded by the California Energy Commission (CEC) under its load modeling project, researchers at Pacific Northwest National Laboratory (PNNL) led the follow-on task to analyze the motor testing data to derive the parameters needed to develop a performance models for the single-phase air-conditioning (SPAC) unit. To derive the performance model, PNNL researchers first used the motor voltage and frequency ramping test data to obtain the real (P) and reactive (Q) power versus voltage (V) and frequency (f) curves. Then, curve fitting was used to develop the P-V, Q-V, P-f, and Q-f relationships for motor running and stalling states. The resulting performance model ignores the dynamic response of the air-conditioning motor. Because the inertia of the air-conditioning motor is very small (H<0.05), the motor reaches from one steady state to another in a few cycles. So, the performance model is a fair representation of the motor behaviors in both running and stalling states.

  11. Modeling zinc toxicity for terrestrial invertebrates.

    PubMed

    Lock, K; Janssen, C R

    2001-09-01

    Acute and chronic ecotoxicity tests with zinc were performed with the earthworm Eisenia fetida, the potworm Enchytraeus albidus, and the springtail Folsomia candida. To assess the influence of the soil type on zinc toxicity for these soil invertebrates, these tests were carried out in a standard artificial soil, a sandy and a loamy field soil. Based on the results of this experimental work and data taken from literature, models were developed relating the ecotoxicity of zinc to the most important parameters controlling bioavailability: pH and cation exchange capacity. Models were developed for E. fetida and F. candida using the regression technique partial least squares projection to latent structures (PLS). Acute as well as chronic toxicity data of both organisms could be normalized on the basis of the pH and the cation exchange capacity of the test soils. For other terrestrial invertebrates, not enough data were available to develop reliable models.

  12. EPA'S CONTROL TECHNOLOGY APPROACH TO ASSISTING STATES AND REGIONS WITH AIR TOXICS PROBLEMS: FIVE CASE STUDIES

    EPA Science Inventory

    The paper discusses a new U.S. strategy to reduce public exposure to toxic air pollutants in the ambient air. he strategy calls for state and local authorities to take on more of the lead regulatory role. he shift in emphasis and responsibility prompted EPA's Offices of Research ...

  13. Carcinogenic Air Toxics Exposure and Their Cancer-Related Health Impacts in the United States

    PubMed Central

    Zhou, Ying; Li, Chaoyang; Huijbregts, Mark A. J.; Mumtaz, M. Moiz

    2015-01-01

    Public health protection from air pollution can be achieved more effectively by shifting from a single-pollutant approach to a multi-pollutant approach. To develop such multi-pollutant approaches, identifying which air pollutants are present most frequently is essential. This study aims to determine the frequently found carcinogenic air toxics or hazardous air pollutants (HAPs) combinations across the United States as well as to analyze the health impacts of developing cancer due to exposure to these HAPs. To identify the most commonly found carcinogenic air toxics combinations, we first identified HAPs with cancer risk greater than one in a million in more than 5% of the census tracts across the United States, based on the National-Scale Air Toxics Assessment (NATA) by the U.S. EPA for year 2005. We then calculated the frequencies of their two-component (binary), and three-component (ternary) combinations. To quantify the cancer-related health impacts, we focused on the 10 most frequently found HAPs with national average cancer risk greater than one in a million. Their cancer-related health impacts were calculated by converting lifetime cancer risk reported in NATA 2005 to years of healthy life lost or Disability-Adjusted Life Years (DALYs). We found that the most frequently found air toxics with cancer risk greater than one in a million are formaldehyde, carbon tetrachloride, acetaldehyde, and benzene. The most frequently occurring binary pairs and ternary mixtures are the various combinations of these four air toxics. Analysis of urban and rural HAPs did not reveal significant differences in the top combinations of these chemicals. The cumulative annual cancer-related health impacts of inhaling the top 10 carcinogenic air toxics included was about 1,600 DALYs in the United States or 0.6 DALYs per 100,000 people. Formaldehyde and benzene together contribute nearly 60 percent of the total cancer-related health impacts. Our study shows that although there are many

  14. Carcinogenic Air Toxics Exposure and Their Cancer-Related Health Impacts in the United States.

    PubMed

    Zhou, Ying; Li, Chaoyang; Huijbregts, Mark A J; Mumtaz, M Moiz

    2015-01-01

    Public health protection from air pollution can be achieved more effectively by shifting from a single-pollutant approach to a multi-pollutant approach. To develop such multi-pollutant approaches, identifying which air pollutants are present most frequently is essential. This study aims to determine the frequently found carcinogenic air toxics or hazardous air pollutants (HAPs) combinations across the United States as well as to analyze the health impacts of developing cancer due to exposure to these HAPs. To identify the most commonly found carcinogenic air toxics combinations, we first identified HAPs with cancer risk greater than one in a million in more than 5% of the census tracts across the United States, based on the National-Scale Air Toxics Assessment (NATA) by the U.S. EPA for year 2005. We then calculated the frequencies of their two-component (binary), and three-component (ternary) combinations. To quantify the cancer-related health impacts, we focused on the 10 most frequently found HAPs with national average cancer risk greater than one in a million. Their cancer-related health impacts were calculated by converting lifetime cancer risk reported in NATA 2005 to years of healthy life lost or Disability-Adjusted Life Years (DALYs). We found that the most frequently found air toxics with cancer risk greater than one in a million are formaldehyde, carbon tetrachloride, acetaldehyde, and benzene. The most frequently occurring binary pairs and ternary mixtures are the various combinations of these four air toxics. Analysis of urban and rural HAPs did not reveal significant differences in the top combinations of these chemicals. The cumulative annual cancer-related health impacts of inhaling the top 10 carcinogenic air toxics included was about 1,600 DALYs in the United States or 0.6 DALYs per 100,000 people. Formaldehyde and benzene together contribute nearly 60 percent of the total cancer-related health impacts. Our study shows that although there are many

  15. Modeling Respiratory Toxicity of Authentic Lunar Dust

    NASA Technical Reports Server (NTRS)

    Santana, Patricia A.; James, John T.; Lam, Chiu-Wing

    2010-01-01

    The lunar expeditions of the Apollo operations from the 60 s and early 70 s have generated awareness about lunar dust exposures and their implication towards future lunar explorations. Critical analyses on the reports from the Apollo crew members suggest that lunar dust is a mild respiratory and ocular irritant. Currently, NASA s space toxicology group is functioning with the Lunar Airborne Dust Toxicity Assessment Group (LADTAG) and the National Institute for Occupational Safety and Health (NIOSH) to investigate and examine toxic effects to the respiratory system of rats in order to establish permissible exposure levels (PELs) for human exposure to lunar dust. In collaboration with the space toxicology group, LADTAG and NIOSH the goal of the present research is to analyze dose-response curves from rat exposures seven and twenty-eight days after intrapharyngeal instillations, and model the response using BenchMark Dose Software (BMDS) from the Environmental Protection Agency (EPA). Via this analysis, the relative toxicities of three types of Apollo 14 lunar dust samples and two control dust samples, titanium dioxide (TiO2) and quartz will be determined. This will be executed for several toxicity endpoints such as cell counts and biochemical markers in bronchoaveolar lavage fluid (BALF) harvested from the rats.

  16. APPLICATION OF JET REMPI AND LIBS TO AIR TOXIC MONITORING

    EPA Science Inventory

    The paper discusses three advanced, laser-based monitoring techniques that the EPA is assisting in developing for real time measurement of toxic aerosol compounds. One of the three techniques is jet resonance enhanced multiphoton ionization (Jet REMPI) coupled with a time-of-flig...

  17. Epidemiologic evidence for asthma and exposure to air toxics: linkages between occupational, indoor, and community air pollution research.

    PubMed Central

    Delfino, Ralph J

    2002-01-01

    Outdoor ambient air pollutant exposures in communities are relevant to the acute exacerbation and possibly the onset of asthma. However, the complexity of pollutant mixtures and etiologic heterogeneity of asthma has made it difficult to identify causal components in those mixtures. Occupational exposures associated with asthma may yield clues to causal components in ambient air pollution because such exposures are often identifiable as single-chemical agents (e.g., metal compounds). However, translating occupational to community exposure-response relationships is limited. Of the air toxics found to cause occupational asthma, only formaldehyde has been frequently investigated in epidemiologic studies of allergic respiratory responses to indoor air, where general consistency can be shown despite lower ambient exposures. The specific volatile organic compounds (VOCs) identified in association with occupational asthma are generally not the same as those in studies showing respiratory effects of VOC mixtures on nonoccupational adult and pediatric asthma. In addition, experimental evidence indicates that airborne polycyclic aromatic hydrocarbon (PAH) exposures linked to diesel exhaust particles (DEPs) have proinflammatory effects on airways, but there is insufficient supporting evidence from the occupational literature of effects of DEPs on asthma or lung function. In contrast, nonoccupational epidemiologic studies have frequently shown associations between allergic responses or asthma with exposures to ambient air pollutant mixtures with PAH components, including black smoke, high home or school traffic density (particularly truck traffic), and environmental tobacco smoke. Other particle-phase and gaseous co-pollutants are likely causal in these associations as well. Epidemiologic research on the relationship of both asthma onset and exacerbation to air pollution is needed to disentangle effects of air toxics from monitored criteria air pollutants such as particle mass

  18. Epidemiologic evidence for asthma and exposure to air toxics: linkages between occupational, indoor, and community air pollution research.

    PubMed

    Delfino, Ralph J

    2002-08-01

    Outdoor ambient air pollutant exposures in communities are relevant to the acute exacerbation and possibly the onset of asthma. However, the complexity of pollutant mixtures and etiologic heterogeneity of asthma has made it difficult to identify causal components in those mixtures. Occupational exposures associated with asthma may yield clues to causal components in ambient air pollution because such exposures are often identifiable as single-chemical agents (e.g., metal compounds). However, translating occupational to community exposure-response relationships is limited. Of the air toxics found to cause occupational asthma, only formaldehyde has been frequently investigated in epidemiologic studies of allergic respiratory responses to indoor air, where general consistency can be shown despite lower ambient exposures. The specific volatile organic compounds (VOCs) identified in association with occupational asthma are generally not the same as those in studies showing respiratory effects of VOC mixtures on nonoccupational adult and pediatric asthma. In addition, experimental evidence indicates that airborne polycyclic aromatic hydrocarbon (PAH) exposures linked to diesel exhaust particles (DEPs) have proinflammatory effects on airways, but there is insufficient supporting evidence from the occupational literature of effects of DEPs on asthma or lung function. In contrast, nonoccupational epidemiologic studies have frequently shown associations between allergic responses or asthma with exposures to ambient air pollutant mixtures with PAH components, including black smoke, high home or school traffic density (particularly truck traffic), and environmental tobacco smoke. Other particle-phase and gaseous co-pollutants are likely causal in these associations as well. Epidemiologic research on the relationship of both asthma onset and exacerbation to air pollution is needed to disentangle effects of air toxics from monitored criteria air pollutants such as particle mass

  19. The importance of toxicity in determining the impact of hazardous air pollutants on the respiratory health of children in Tennessee.

    PubMed

    Moore, Roberta J H; Hotchkiss, Julie L

    2016-09-01

    Respiratory diseases, exacerbated through point source pollution, are currently among the leading causes of hospitalization of children in the United States. This paper investigates the relationship between the proximity of hazardous air pollutants (HAPs) emitted from Toxic Release Inventory (TRI) facilities and the number of children diagnosed in hospitals with a respiratory disease in Tennessee. The importance of controlling for toxicity of those HAPs is of particular interest. Hospital discharge, socioeconomic, TRI emission, and HAP toxicity data are used to estimate, via Generalized Linear Methods, a logistic regression model describing the relationship between the percent of children living in a zip code area treated for respiratory illness and the average annual emissions over the previous 10 years of HAPs from TRI sites in that area. Controlling for area socioeconomic characteristics, we find that accounting for toxicity is important in uncovering the relationship between HAP emissions and respiratory health of children. A one standard deviation increase in toxicity-weighted emissions per 100 square miles is associated with an increase in the number of children diagnosed with asthma (chronic bronchitis) by about 1205 (260). The evidence suggests that, with a goal to improving children's respiratory health, monitoring the toxicity of chemicals being emitted is at least as important as simply monitoring total emission levels. This suggests that the EPA should consider making efforts toward establishing toxicity adjusted emission guidelines. PMID:27342000

  20. Distribution of toxic and radiation components in air particulates.

    PubMed

    Rausch, H; Sziklai, I L; Borossay, J; Torkos, K; Rikker, T; Zemplén-Papp, E

    1995-12-01

    The concentrations of several toxic heavy metals and volatile organic compounds (VOCs) in various types of Hungarian fly-ash fine particulates were investigated by means of instrumental neutron activation analysis, X-ray fluorescence analysis and gas chromatography, coupled with mass spectrometry. Within a power station, particulate samples were taken from the boiler zone (BO), from the electrostatic dust filter chamber (FI) and from the flue-gas at the top of the stack (ST). Enrichment rates of the toxic metals both in FI and ST particulate fractions related to the BO concentrations were calculated to enable the temperature dependence on the adsorption of the toxic components to be studied. In addition, both the total amounts of the VOCs and their partial distributions in accordance with the number of carbon atoms were also studied in fly-ash particulates. From them, 31 organic species were identified and determined. Since Hungarian brown coals have high uranium and thorium contents, the specific radioactivities of the daughter isotopes of both the 232Th and 238U decay series were also measured and are discussed.

  1. Formaldehyde: a candidate toxic air contaminant. Final report

    SciTech Connect

    Frye, B.; Parker, T.

    1988-03-01

    Formaldehyde (HCHO) is a gas widely used in adhesives and resins, textiles, embalming fluids, fungicides, air fresheners, and cosmetics. It is directly emitted into the ambient outdoor air from vehicular and stationary sources, and is also produced in the atmosphere from other substances by photochemical smog processes. The International Agency for Research on Cancer (IARC) has determined that there is sufficient evidence for carcinogenicity of formaldehyde to animals, and limited evidence for carcinogenicity to humans. EPA classifies formaldehyde as a probable human carcinogen with a one in a million risk concentration of 0.08 ppb.

  2. Personal and ambient exposures to air toxics in Camden, New Jersey.

    PubMed

    Lioy, Paul J; Fan, Zhihua; Zhang, Junfeng; Georgopoulos, Panos; Wang, Sheng-Wei; Ohman-Strickland, Pamela; Wu, Xiangmei; Zhu, Xianlei; Harrington, Jason; Tang, Xiaogang; Meng, Qingyu; Jung, Kyung Hwa; Kwon, Jaymin; Hernandez, Marta; Bonnano, Linda; Held, Joann; Neal, John

    2011-08-01

    Personal exposures and ambient concentrations of air toxics were characterized in a pollution "hot spot" and an urban reference site, both in Camden, New Jersey. The hot spot was the city's Waterfront South neighborhood; the reference site was a neighborhood, about 1 km to the east, around the intersection of Copewood and Davis streets. Using personal exposure measurements, residential ambient air measurements, statistical analyses, and exposure modeling, we examined the impact of local industrial and mobile pollution sources, particularly diesel trucks, on personal exposures and ambient concentrations in the two neighborhoods. Presented in the report are details of our study design, sample and data collection methods, data- and model-analysis approaches, and results and key findings of the study. In summary, 107 participants were recruited from nonsmoking households, including 54 from Waterfront South and 53 from the Copewood-Davis area. Personal air samples were collected for 24 hr and measured for 32 target compounds--11 volatile organic compounds (VOCs*), four aldehydes, 16 polycyclic aromatic hydrocarbons (PAHs), and particulate matter (PM) with an aerodynamic diameter < or = 2.5 microm (PM2.5). Simultaneously with the personal monitoring, ambient concentrations of the target compounds were measured at two fixed monitoring sites, one each in the Waterfront South and Copewood-Davis neighborhoods. To understand the potential impact of local sources of air toxics on personal exposures caused by temporal (weekdays versus weekend days) and seasonal (summer versus winter) variations in source intensities of the air toxics, four measurements were made of each subject, two in summer and two in winter. Within each season, one measurement was made on a weekday and the other on a weekend day. A baseline questionnaire and a time diary with an activity questionnaire were administered to each participant in order to obtain information that could be used to understand

  3. Uncertainty in Air Quality Modeling.

    NASA Astrophysics Data System (ADS)

    Fox, Douglas G.

    1984-01-01

    Under the direction of the AMS Steering Committee for the EPA Cooperative Agreement on Air Quality Modeling, a small group of scientists convened to consider the question of uncertainty in air quality modeling. Because the group was particularly concerned with the regulatory use of models, its discussion focused on modeling tall stack, point source emissions.The group agreed that air quality model results should be viewed as containing both reducible error and inherent uncertainty. Reducible error results from improper or inadequate meteorological and air quality data inputs, and from inadequacies in the models. Inherent uncertainty results from the basic stochastic nature of the turbulent atmospheric motions that are responsible for transport and diffusion of released materials. Modelers should acknowledge that all their predictions to date contain some associated uncertainty and strive also to quantify uncertainty.How can the uncertainty be quantified? There was no consensus from the group as to precisely how uncertainty should be calculated. One subgroup, which addressed statistical procedures, suggested that uncertainty information could be obtained from comparisons of observations and predictions. Following recommendations from a previous AMS workshop on performance evaluation (Fox. 1981), the subgroup suggested construction of probability distribution functions from the differences between observations and predictions. Further, they recommended that relatively new computer-intensive statistical procedures be considered to improve the quality of uncertainty estimates for the extreme value statistics of interest in regulatory applications.A second subgroup, which addressed the basic nature of uncertainty in a stochastic system, also recommended that uncertainty be quantified by consideration of the differences between observations and predictions. They suggested that the average of the difference squared was appropriate to isolate the inherent uncertainty that

  4. Indoor/ambient residential air toxics results in rural western Montana.

    PubMed

    Ward, Tony J; Underberg, Heidi; Jones, David; Hamilton, Raymond F; Adams, Earle

    2009-06-01

    Indoor and ambient concentrations of 21 volatile organic compounds (including 14 hazardous air pollutants) were measured in the homes of nearly 80 western Montana (Missoula) high school students as part of the 'Air Toxics Under the Big Sky' program during the 2004/2005 and 2005/2006 school years. Target analytes were measured using low flow air sampling pumps and sorbent tubes, with analysis of the exposed samples by thermal desorption/gas chromatography/mass spectrometry (TD/GC/MS). The results reported here present the findings of the first indoor/ambient air toxics monitoring program conducted in a semi-rural valley location located in the Northern Rocky Mountain/Western Montana region. Of all of the air toxics quantified in this study, toluene was found to be the most abundant compound in both the indoor and ambient environments during each of the two school years. Indoor log-transformed mean concentrations were found to be higher when compared with ambient log-transformed mean concentrations at P < 0.001 for the majority of the compounds, supporting the results of previous studies conducted in urban areas. For the air toxics consistently measured throughout this program, concentrations were approximately six times higher inside the student's homes compared to those simultaneously measured directly outside their homes. For the majority of the compounds, there were no significant correlations between indoor and ambient concentrations.

  5. EMISSIONS OF AIR TOXICS FROM A SIMULATED CHARCOAL KILN

    EPA Science Inventory

    The report gives results of experiments in a laboratory-scale charcoal kiln simulator to evaluate emissions of hazardous air pollutants from the production of charcoal in Missouri-type kilns. Fixed combustion gases were measured using continuous monitors. In Addition, other pollu...

  6. MEASUREMENT OF LOW LEVEL AIR TOXICS WITH MODIFIED UV DOAS

    EPA Science Inventory

    To further understand near source impacts, EPA is working to develop open-path optical techniques for spatiotemporal-resolved measurement of air pollutants. Of particular interest is near real time quantification of mobile-source generated CO, Nox and hydrocarbons measured in cl...

  7. 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 ...

  8. Paradigm shift in toxicity testing and modeling.

    PubMed

    Sun, Hongmao; Xia, Menghang; Austin, Christopher P; Huang, Ruili

    2012-09-01

    The limitations of traditional toxicity testing characterized by high-cost animal models with low-throughput readouts, inconsistent responses, ethical issues, and extrapolability to humans call for alternative strategies for chemical risk assessment. A new strategy using in vitro human cell-based assays has been designed to identify key toxicity pathways and molecular mechanisms leading to the prediction of an in vivo response. The emergence of quantitative high-throughput screening (qHTS) technology has proved to be an efficient way to decompose complex toxicological end points to specific pathways of targeted organs. In addition, qHTS has made a significant impact on computational toxicology in two aspects. First, the ease of mechanism of action identification brought about by in vitro assays has enhanced the simplicity and effectiveness of machine learning, and second, the high-throughput nature and high reproducibility of qHTS have greatly improved the data quality and increased the quantity of training datasets available for predictive model construction. In this review, the benefits of qHTS routinely used in the US Tox21 program will be highlighted. Quantitative structure-activity relationships models built on traditional in vivo data and new qHTS data will be compared and analyzed. In conjunction with the transition from the pilot phase to the production phase of the Tox21 program, more qHTS data will be made available that will enrich the data pool for predictive toxicology. It is perceivable that new in silico toxicity models based on high-quality qHTS data will achieve unprecedented reliability and robustness, thus becoming a valuable tool for risk assessment and drug discovery.

  9. In vitro models for liver toxicity testing

    PubMed Central

    Soldatow, Valerie Y.; LeCluyse, Edward L.; Griffith, Linda G.; Rusyn, Ivan

    2013-01-01

    Over the years, various liver-derived in vitro model systems have been developed to enable investigation of the potential adverse effects of chemicals and drugs. Liver tissue slices, isolated microsomes, perfused liver, immortalized cell lines, and primary hepatocytes have been used extensively. Immortalized cell lines and primary isolated liver cells are currently most widely used in vitro models for liver toxicity testing. Limited throughput, loss of viability, and decreases in liver-specific functionality and gene expression are common shortcomings of these models. Recent developments in the field of in vitro hepatotoxicity include three-dimensional tissue constructs and bioartificial livers, co-cultures of various cell types with hepatocytes, and differentiation of stem cells into hepatic lineage-like cells. In an attempt to provide a more physiological environment for cultured liver cells, some of the novel cell culture systems incorporate fluid flow, micro-circulation, and other forms of organotypic microenvironments. Co-cultures aim to preserve liver-specific morphology and functionality beyond those provided by cultures of pure parenchymal cells. Stem cells, both embryonic- and adult tissue-derived, may provide a limitless supply of hepatocytes from multiple individuals to improve reproducibility and enable testing of the individual-specific toxicity. This review describes various traditional and novel in vitro liver models and provides a perspective on the challenges and opportunities afforded by each individual test system. PMID:23495363

  10. FINE SCALE AIR QUALITY MODELING USING DISPERSION AND CMAQ MODELING APPROACHES: AN EXAMPLE APPLICATION IN WILMINGTON, DE

    EPA Science Inventory

    Characterization of spatial variability of air pollutants in an urban setting at fine scales is critical for improved air toxics exposure assessments, for model evaluation studies and also for air quality regulatory applications. For this study, we investigate an approach that su...

  11. Wind tunnel modeling of toxic gas releases at industrial facilities

    SciTech Connect

    Petersen, R.L.

    1994-12-31

    Government agencies and the petroleum, chemical and gas industries in the US and abroad have become increasingly concerned about the issues of toxic gas dispersal. Because of this concern, research programs have been sponsored by these various groups to improve the capabilities in hazard mitigation and response. Present computer models used to predict pollutant concentrations at industrial facilities do not properly account for the effects of structures. Structures can act to trap or deflect the cloud and modify the cloud dimensions, thereby possibly increasing or reducing downwind concentrations. The main purpose of this evaluation was to develop a hybrid modeling approach, which combines wind tunnel and dispersion modeling, to obtain more accurate concentration estimates when buildings or structures affect the dispersion of hazardous chemical vapors. To meet the study objectives, wind tunnel testing was performed on a building cluster typical of two industrial settings where accidental releases of toxic gases might occur. This data set was used to test the validity of the AFTOX and SLAB models for estimating concentrations and was used to develop and test two hybrid models. Two accident scenarios were simulated, an evaporating pool of a gas slightly heavier than air (Hydrazine-N{sub 2}H{sub 4}) and a liquid jet release of Nitrogen Tetroxide (N{sub 2}O{sub 4}) where dense gas dispersion effects would be significant. Tests were conducted for a range of wind directions and wind speeds for two different building configurations (low rise and high rise structures).

  12. Risk of leukemia in relation to exposure to ambient air toxics in pregnancy and early childhood.

    PubMed

    Heck, Julia E; Park, Andrew S; Qiu, Jiaheng; Cockburn, Myles; Ritz, Beate

    2014-07-01

    There are few established causes of leukemia, the most common type of cancer in children. Studies in adults suggest a role for specific environmental agents, but little is known about any effect from exposures in pregnancy to toxics in ambient air. In our case-control study, we ascertained 69 cases of acute lymphoblastic leukemia (ALL) and 46 cases of acute myeloid leukemia (AML) from California Cancer Registry records of children air toxics monitoring station between 1990 and 2007. Information on air toxics exposures was taken from community air monitors. We used logistic regression to estimate the risk of leukemia associated with one interquartile range increase in air toxic exposure. Risk of ALL was elevated with 3(rd) trimester exposure to polycyclic aromatic hydrocarbons (OR=1.16, 95% CI 1.04, 1.29), arsenic (OR=1.33, 95% CI 1.02, 1.73), benzene (OR=1.50, 95% CI 1.08, 2.09), and three other toxics related to fuel combustion. Risk of AML was increased with 3rd trimester exposure to chloroform (OR=1.30, 95% CI 1.00, 1.69), benzene (1.75, 95% CI 1.04, 2.93), and two other traffic-related toxics. During the child's first year, exposure to butadiene, ortho-xylene, and toluene increased risk for AML and exposure to selenium increased risk for ALL. Benzene is an established cause of leukemia in adults; this study supports that ambient exposures to this and other chemicals in pregnancy and early life may also increase leukemia risk in children.

  13. Risk of leukemia in relation to exposure to ambient air toxics in pregnancy and early childhood

    PubMed Central

    Heck, Julia E; Park, Andrew S; Qiu, Jiaheng; Cockburn, Myles; Ritz, Beate

    2014-01-01

    There are few established causes of leukemia, the most common type of cancer in children. Studies in adults suggest a role for specific environmental agents, but little is known about any effect from exposures in pregnancy to toxics in ambient air. In our case-control study, we ascertained 69 cases of acute lymphoblastic leukemia (ALL) and 46 cases of acute myeloid leukemia (AML) from California Cancer Registry records of children < age 6, and 19,209 controls from California birth records within 2km (1.3 miles) (ALL) and 6km (3.8 miles) (AML) of an air toxics monitoring station between 1990–2007. Information on air toxics exposures was taken from community air monitors. We used logistic regression to estimate the risk of leukemia associated with one interquartile range increase in air toxic exposure. Risk of ALL was elevated with 3rd trimester exposure to polycyclic aromatic hydrocarbons (OR=1.16, 95%CI 1.04, 1.29), arsenic (OR=1.33, 95%CI 1.02, 1.73), benzene (OR=1.50, 95%CI 1.08, 2.09), and three other toxics related to fuel combustion. Risk of AML was increased with 3rd trimester exposure to chloroform (OR=1.30, 95%CI 1.00, 1.69), benzene (1.75, 95%CI 1.04, 2.93), and two other traffic-related toxics. During the child’s first year, exposure to butadiene, ortho-xylene, and toluene increased risk for AML and exposure to selenium increased risk for ALL. Benzene is an established cause of leukemia in adults; this study supports that ambient exposures to this and other chemicals in pregnancy and early life may also increase leukemia risk in children. PMID:24472648

  14. AIR QUALITY MODELING OF HAZARDOUS POLLUTANTS: CURRENT STATUS AND FUTURE DIRECTIONS

    EPA Science Inventory

    The paper presents a review of current air toxics modeling applications and discusses possible advanced approaches. Many applications require the ability to predict hot spots from industrial sources or large roadways that are needed for community health and Environmental Justice...

  15. Risk Assessment for Toxic Air Pollutants: A Citizen's Guide

    MedlinePlus

    ... from the source(s). Engineers use either monitors or computer models to estimate the amount of pollutant released ... measure how much of the pollutant is present. Computer models use mathematical equations that represent the processes ...

  16. Air toxic emissions from the combustion of coal: Identifying and quantifying hazardous air pollutants from US coals

    SciTech Connect

    Szpunar, C.B.

    1992-09-01

    This report addresses the key air toxic emissions likely to emanate from continued and expanded use of domestic coal. It identifies and quantifies those trace elements specified in the US 1990 Clean Air Act Amendments, by tabulating selected characterization data on various source coals by region, state, and rank. On the basis of measurements by various researchers, this report also identifies those organic compounds likely to be derived from the coal combustion process (although their formation is highly dependent on specific boiler configurations and operating conditions).

  17. Personal and ambient exposures to air toxics in Camden, New Jersey.

    PubMed

    Lioy, Paul J; Fan, Zhihua; Zhang, Junfeng; Georgopoulos, Panos; Wang, Sheng-Wei; Ohman-Strickland, Pamela; Wu, Xiangmei; Zhu, Xianlei; Harrington, Jason; Tang, Xiaogang; Meng, Qingyu; Jung, Kyung Hwa; Kwon, Jaymin; Hernandez, Marta; Bonnano, Linda; Held, Joann; Neal, John

    2011-08-01

    Personal exposures and ambient concentrations of air toxics were characterized in a pollution "hot spot" and an urban reference site, both in Camden, New Jersey. The hot spot was the city's Waterfront South neighborhood; the reference site was a neighborhood, about 1 km to the east, around the intersection of Copewood and Davis streets. Using personal exposure measurements, residential ambient air measurements, statistical analyses, and exposure modeling, we examined the impact of local industrial and mobile pollution sources, particularly diesel trucks, on personal exposures and ambient concentrations in the two neighborhoods. Presented in the report are details of our study design, sample and data collection methods, data- and model-analysis approaches, and results and key findings of the study. In summary, 107 participants were recruited from nonsmoking households, including 54 from Waterfront South and 53 from the Copewood-Davis area. Personal air samples were collected for 24 hr and measured for 32 target compounds--11 volatile organic compounds (VOCs*), four aldehydes, 16 polycyclic aromatic hydrocarbons (PAHs), and particulate matter (PM) with an aerodynamic diameter < or = 2.5 microm (PM2.5). Simultaneously with the personal monitoring, ambient concentrations of the target compounds were measured at two fixed monitoring sites, one each in the Waterfront South and Copewood-Davis neighborhoods. To understand the potential impact of local sources of air toxics on personal exposures caused by temporal (weekdays versus weekend days) and seasonal (summer versus winter) variations in source intensities of the air toxics, four measurements were made of each subject, two in summer and two in winter. Within each season, one measurement was made on a weekday and the other on a weekend day. A baseline questionnaire and a time diary with an activity questionnaire were administered to each participant in order to obtain information that could be used to understand

  18. Air toxics being measured more accurately, controlled more effectively

    SciTech Connect

    1995-04-01

    In response to the directives of the Clean Air Act Amendments, Argonne National Laboratory is developing new or improved pollutant control technologies for industries that burn fossil fuels. This research continues Argonne`s traditional support for the US DOE Flue Gas Cleanup Program. Research is underway to measure process emissions and identify new and improved control measures. Argonne`s emission control research has ranged from experiments in the basic chemistry of pollution-control systems, through laboratory-scale process development and testing to pilot-scale field tests of several technologies. Whenever appropriate, the work has emphasized integrated or combined control systems as the best approach to technologies that offer low cost and good operating characteristics.

  19. Water quality-based toxics evaluation of Reconquista River, Province of Buenos Aires, Argentina

    SciTech Connect

    Herkovits, J.; Herkovits, F.D.; Perez-Coll, C.S.

    1995-12-31

    The water quality based toxics control is essential to evaluate the aggregate toxicity, bioavailability as well as for the detection and/or prediction of ecological impacts. Reconquista River valley is situated in the north area of Great Buenos Aires with a population of three million inhabitants. The river is loaded with industrial and municipal waste water. In the present preliminary study the authors report the toxicity found in surface water at a 6 sample stations (including a reference point and a stream) all of them downstream from mixing zone areas. The ecotoxicological study was performed with three native species (Bufo arenarum embryos, Cnesterodon decemmaculatus and a species of shrimp collected in an upstream reference site) during a 7 day renewal toxicity test conducted with 10 individuals (by duplicate) for each condition plus control. The results point out that the Bufo arenarum embryos test is the most sensitive to toxic substances as well as the better adapted species to the changing physico-chemical conditions of this river. The results obtained with embryos, expressed in Acute and Chronic Toxicity Units (according USEPA) range between <0.3--2 and <1--5 respectively (recommended magnitudes for industrial effluents according USEPA: 0.3 and 1 toxicity units respectively). Therefore, the toxicity found in Reconquista River ecosystem was up to 6 times higher than the maximal value recommended for industrial effluents. It is noteworthy that in the place where toxicity starts to rise, a large number of dead fishes were found and from that place downstream, no macroorganisms were found in the river. The results confirm the high sensitivity of Bufo arenarum embryos for continental waters ecotoxicological studies and the possibility of using this test as a short-term chronic toxicity method for water quality-based toxics control.

  20. APPLICATIONS ANALYSIS REPORT: TOXIC TREATMENTS, IN-SITU STEAM/HOT-AIR STRIPPING TECHNOLOGY

    EPA Science Inventory

    This document is an evaluation of the performance of the Toxic Treatments (USA), Inc., (TTUSA) in situ steam/hot-air stripping technology and its applicability as an on-site treatment technique for hazardous waste site soil cleanup of volatile and semivolatile contaminants. Both ...

  1. DETERMINANTS OF HUMAN EXPOSURES TO AIR TOXICS AND ASSOCIATED HEALTH EFFECTS

    EPA Science Inventory

    Individuals are exposed to wide variety of air toxics in various indoor and outdoor microenvironments during the course of their daily activities. Sources of emissions include a wide variety of indoor and outdoor sources, including stationary and mobile sources, building material...

  2. Temporal and modal characterization of DoD source air toxic emission factors: final report

    EPA Science Inventory

    This project tested three, real-/near real-time monitoring techniques to develop air toxic emission factors for Department of Defense (DoD) platform sources. These techniques included: resonance enhanced multi photon ionization time of flight mass spectrometry (REMPI-TOFMS) for o...

  3. CORONA DESTRUCTION: AN INNOVATIVE CONTROL TECHNOLOGY FOR VOCS AND AIR TOXICS

    EPA Science Inventory

    This paper discusses the work and results to date leading to the demonstration of the corona destruction process at pilot scale. The research effort in corona destruction of volatile organic compounds (VOCs) and air toxics has shown significant promise for providing a valuable co...

  4. Evaluation of air toxic emissions from advanced and conventional coal-fired power plants

    SciTech Connect

    Chu, P.; Epstein, M.; Gould, L.; Botros, P.

    1995-12-31

    This paper evaluates the air toxics measurements at three advanced power systems and a base case conventional fossil fuel power plant. The four plants tested include a pressurized fluidized bed combustor, integrated gasification combined cycle, circulating fluidized bed combustor, and a conventional coal-fired plant.

  5. EMISSIONS OF AIR TOXICS FROM A SIMULATED CHARCOAL KILN EQUIPPED WITH AN AFTERBURNER

    EPA Science Inventory

    The report discusses emissions of air toxics from a simulated charcoal kiln equipped with an afterburner. A laboratory-scale simulator was constructed and tested to determine if it could be used to produce charcoal that was similar to that produced in Missouri-type charcoal kilns...

  6. CRITERIA AND AIR TOXIC EMISSIONS FROM IN-USE, LOW EMISSION VEHICLES (LEVS)

    EPA Science Inventory

    The U.S. Environmental Protection Agency implemented a program to identify tailpipe emissions of criteria and air toxic contaminants from in-use, light-duty Low Emission Vehicles (LEVs). EPA recruited twenty-five LEVs in 2002, and measured emissions on a chassis dynamometer usin...

  7. The effects of forced air flow and oxygen concentration on flammability, smoke density, and pyrolytic toxicity

    NASA Technical Reports Server (NTRS)

    Sauers, D. G.

    1976-01-01

    The question is posed whether forced air flow should be incorporated into flammability tests as a relevant variable. A test apparatus is described which permits tests to be conducted on small test specimens in a forced flow which is (continuously) variable over flow velocities from zero to 300 feet per minute (1.52 m/s). The effects of air-flow rate and oxygen concentration on flame propagation rate, maximum smoke density, and pyrolytic product toxicity were measured for a single material and were statistically evaluated. Regression analysis was used to graph the resulting relationships. It is concluded that air velocity is an important variable for laboratory flammability testing.

  8. Air pollution modeling and its application III

    SciTech Connect

    De Wispelaere, C.

    1984-01-01

    This book focuses on the Lagrangian modeling of air pollution. Modeling cooling tower and power plant plumes, modeling the dispersion of heavy gases, remote sensing as a tool for air pollution modeling, dispersion modeling including photochemistry, and the evaluation of model performances in practical applications are discussed. Specific topics considered include dispersion in the convective boundary layer, the application of personal computers to Lagrangian modeling, the dynamic interaction of cooling tower and stack plumes, the diffusion of heavy gases, correlation spectrometry as a tool for mesoscale air pollution modeling, Doppler acoustic sounding, tetroon flights, photochemical air quality simulation modeling, acid deposition of photochemical oxidation products, atmospheric diffusion modeling, applications of an integral plume rise model, and the estimation of diffuse hydrocarbon leakages from petrochemical factories. This volume constitutes the proceedings of the Thirteenth International Technical Meeting on Air Pollution Modeling and Its Application held in France in 1982.

  9. Energy and environmental research emphasizing low-rank coal -- Task 2.4, Air toxic fine particulate control

    SciTech Connect

    Dunham, G.E.; Heidt, M.K.; Miller, S.J.

    1995-03-01

    Emission from coal-fired boilers is an issue because of the current concern over atmospheric air toxics, which contain high concentrations of trace elements. The best method of minimizing the emission of these air toxic trace elements to the atmosphere is to install high-efficiency fine-particle control devices. After collection, the dust must be removed from the filter bags or electrostatic precipitator (ESP) plates and transferred to the hopper without significant redispersion. Since it is more difficult to collect fine particles, the extent to which the dust is redispersed into its original particle-size distribution will have a major impact on the overall fine-particle collection efficiency of the filter or ESP and, subsequently, the collection efficiency of air toxic metals. The goal of Task 2.4 was to evaluate redispersion of dust in particulate control devices so that the appropriate methods to minimize redispersion can be implemented. The primary objective was to determine the extent that fly ash is redispersed as individual particles upon cleaning of the filters or ESP plates. The current research was to determine if the level of redispersion of fly ash correlates with measurable cohesive dust properties. This will contribute to the long-term project goal of developing models to the point where they can be used to help design particulate control devices for the lowest level of fine-particle emissions at a reasonable cost.

  10. Assessment of Sociodemographic and Geographic Disparities in Cancer Risk from Air Toxics in South Carolina

    PubMed Central

    Wilson, Sacoby; Burwell-Naney, Kristen; Jiang, Chengsheng; Zhang, Hongmei; Samantapudi, Ashok; Murray, Rianna; Dalemarre, Laura; Rice, LaShanta; Williams, Edith

    2015-01-01

    Populations of color and low-income communities are often disproportionately burdened by exposures to various environmental contaminants, including air pollution. Some air pollutants have carcinogenic properties that are particularly problematic in South Carolina (SC), a state that consistently has high rates of cancer mortality for all sites. The purpose of this study was to assess cancer risk disparities in SC by linking risk estimates from the U.S. Environmental Protection Agency’s 2005 National Air Toxics Assessment (NATA) with sociodemographic data from the 2000 US Census Bureau. Specifically, NATA risk data for varying risk categories were linked by tract ID and analyzed with sociodemographic variables from the 2000 census using R. The average change in cancer risk from all sources by sociodemographic variable was quantified using multiple linear regression models. Spatial methods were further employed using ArcGIS 10 to assess the distribution of all source risk and percent non-white at each census tract level. The relative risk estimates of the proportion of high cancer risk tracts (defined as the top 10% of cancer risk in SC) and their respective 95% confidence intervals (CIs) were calculated between the first and latter three quartiles defined by sociodemographic factors, while the variance in the percentage of high cancer risk between quartile groups was tested using Pearson’s chi-square. The average total cancer risk for SC was 26.8 people/million (ppl/million). The risk from on-road sources was approximately 5.8 ppl/million, higher than the risk from major, area, and non-road sources (1.8, 2.6, and 1.3 ppl/million), respectively. Based on our findings, addressing on-road sources may decrease the disproportionate cancer risk burden among low-income populations and communities of color in SC. PMID:26037107

  11. Assessment of sociodemographic and geographic disparities in cancer risk from air toxics in South Carolina.

    PubMed

    Wilson, Sacoby; Burwell-Naney, Kristen; Jiang, Chengsheng; Zhang, Hongmei; Samantapudi, Ashok; Murray, Rianna; Dalemarre, Laura; Rice, LaShanta; Williams, Edith

    2015-07-01

    Populations of color and low-income communities are often disproportionately burdened by exposures to various environmental contaminants, including air pollution. Some air pollutants have carcinogenic properties that are particularly problematic in South Carolina (SC), a state that consistently has high rates of cancer mortality for all sites. The purpose of this study was to assess cancer risk disparities in SC by linking risk estimates from the U.S. Environmental Protection Agency's 2005 National Air Toxics Assessment (NATA) with sociodemographic data from the 2000 US Census Bureau. Specifically, NATA risk data for varying risk categories were linked by tract ID and analyzed with sociodemographic variables from the 2000 census using R. The average change in cancer risk from all sources by sociodemographic variable was quantified using multiple linear regression models. Spatial methods were further employed using ArcGIS 10 to assess the distribution of all source risk and percent non-white at each census tract level. The relative risk (RR) estimates of the proportion of high cancer risk tracts (defined as the top 10% of cancer risk in SC) and their respective 95% confidence intervals (CIs) were calculated between the first and latter three quartiles defined by sociodemographic factors, while the variance in the percentage of high cancer risk between quartile groups was tested using Pearson's chi-square. The average total cancer risk for SC was 26.8 people/million (ppl/million). The risk from on-road sources was approximately 5.8 ppl/million, higher than the risk from major, area, and non-road sources (1.8, 2.6, and 1.3 ppl/million), respectively. Based on our findings, addressing on-road sources may decrease the disproportionate cancer risk burden among low-income populations and communities of color in SC.

  12. Assessment of sociodemographic and geographic disparities in cancer risk from air toxics in South Carolina.

    PubMed

    Wilson, Sacoby; Burwell-Naney, Kristen; Jiang, Chengsheng; Zhang, Hongmei; Samantapudi, Ashok; Murray, Rianna; Dalemarre, Laura; Rice, LaShanta; Williams, Edith

    2015-07-01

    Populations of color and low-income communities are often disproportionately burdened by exposures to various environmental contaminants, including air pollution. Some air pollutants have carcinogenic properties that are particularly problematic in South Carolina (SC), a state that consistently has high rates of cancer mortality for all sites. The purpose of this study was to assess cancer risk disparities in SC by linking risk estimates from the U.S. Environmental Protection Agency's 2005 National Air Toxics Assessment (NATA) with sociodemographic data from the 2000 US Census Bureau. Specifically, NATA risk data for varying risk categories were linked by tract ID and analyzed with sociodemographic variables from the 2000 census using R. The average change in cancer risk from all sources by sociodemographic variable was quantified using multiple linear regression models. Spatial methods were further employed using ArcGIS 10 to assess the distribution of all source risk and percent non-white at each census tract level. The relative risk (RR) estimates of the proportion of high cancer risk tracts (defined as the top 10% of cancer risk in SC) and their respective 95% confidence intervals (CIs) were calculated between the first and latter three quartiles defined by sociodemographic factors, while the variance in the percentage of high cancer risk between quartile groups was tested using Pearson's chi-square. The average total cancer risk for SC was 26.8 people/million (ppl/million). The risk from on-road sources was approximately 5.8 ppl/million, higher than the risk from major, area, and non-road sources (1.8, 2.6, and 1.3 ppl/million), respectively. Based on our findings, addressing on-road sources may decrease the disproportionate cancer risk burden among low-income populations and communities of color in SC. PMID:26037107

  13. Separate and Unequal: Residential Segregation and Estimated Cancer Risks Associated with Ambient Air Toxics in U.S. Metropolitan Areas

    PubMed Central

    Morello-Frosch, Rachel; Jesdale, Bill M.

    2006-01-01

    This study examines links between racial residential segregation and estimated ambient air toxics exposures and their associated cancer risks using modeled concentration estimates from the U.S. Environmental Protection Agency’s National Air Toxics Assessment. We combined pollutant concentration estimates with potencies to calculate cancer risks by census tract for 309 metropolitan areas in the United States. This information was combined with socioeconomic status (SES) measures from the 1990 Census. Estimated cancer risks associated with ambient air toxics were highest in tracts located in metropolitan areas that were highly segregated. Disparities between racial/ethnic groups were also wider in more segregated metropolitan areas. Multivariate modeling showed that, after controlling for tract-level SES measures, increasing segregation amplified the cancer risks associated with ambient air toxics for all racial groups combined [highly segregated areas: relative cancer risk (RCR) = 1.04; 95% confidence interval (CI), 1.01–107; extremely segregated areas: RCR = 1.32; 95% CI, 1.28–1.36]. This segregation effect was strongest for Hispanics (highly segregated areas: RCR = 1.09; 95% CI, 1.01–1.17; extremely segregated areas: RCR = 1.74; 95% CI, 1.61–1.88) and weaker among whites (highly segregated areas: RCR = 1.04; 95% CI, 1.01–1.08; extremely segregated areas: RCR = 1.28; 95% CI, 1.24–1.33), African Americans (highly segregated areas: RCR = 1.09; 95% CI, 0.98–1.21; extremely segregated areas: RCR = 1.38; 95% CI, 1.24–1.53), and Asians (highly segregated areas: RCR = 1.10; 95% CI, 0.97–1.24; extremely segregated areas: RCR = 1.32; 95% CI, 1.16–1.51). Results suggest that disparities associated with ambient air toxics are affected by segregation and that these exposures may have health significance for populations across racial lines. PMID:16507462

  14. Identification of ambient air sampling and analysis methods for the 189 Title III air toxics

    SciTech Connect

    Mukund, R.; Kelly, T.J.; Gordon, S.M.; Hays, M.J.

    1994-12-31

    The state of development of ambient air measurement methods for the 189 Hazardous Air Pollution (HAPs) in Title 3 of the Clean Air Act Amendments was surveyed. Measurement methods for the HAPs were identified by reviews of established methods, and by literature searches for pertinent research techniques. Methods were segregated by their degree of development into Applicable, Likely, and Potential methods. This survey identified a total of 183 methods, applicable at varying degrees to ambient air measurements of one or more HAPs. As a basis for classifying the HAPs and evaluating the applicability of measurement methods, a survey of a variety of chemical and physical properties of the HAPs was also conducted. The results of both the methods and properties surveys were tabulated for each of the 189 HAP. The current state of development of ambient measurement methods for the 189 HAPs was then assessed from the results of the survey, and recommendations for method development initiatives were developed.

  15. SAR STUDY OF NASAL TOXICITY: LESSONS FOR MODELING SMALL TOXICITY DATASETS

    EPA Science Inventory

    Most toxicity data, particularly from whole animal bioassays, are generated without the needs or capabilities of structure-activity relationship (SAR) modeling in mind. Some toxicity endpoints have been of sufficient regulatory concern to warrant large scale testing efforts (e.g....

  16. Air toxics concentrations, source identification, and health risks: An air pollution hot spot in southwest Memphis, TN

    NASA Astrophysics Data System (ADS)

    Jia, Chunrong; Foran, Jeffery

    2013-12-01

    Southwest Memphis is a residential region surrounded by fossil fuel burning, steel, refining, and food processing industries, and considerable mobile sources whose emissions may pose adverse health risks to local residents. This study characterizes cancer and non-cancer risks resulting from exposure to ambient air toxics in southwest Memphis. Air toxics samples were collected at a central location every 6 days from June 5, 2008 to January 8, 2010. Volatile organic compounds (VOCs) were collected in evacuated stainless-steel canisters and aldehydes by DNPH cartridges, and samples were analyzed for 73 target compounds. A total of 60 compounds were detected and 39 were found in over 86% of the samples. Mean concentrations of many compounds were higher than those measured in many industrial communities throughout the U.S. The cumulative cancer risk associated with exposure to 13 carcinogens found in southwest Memphis air was 2.3 × 10-4, four times higher than the national average of 5.0 × 10-5. Three risk drivers were identified: benzene, formaldehyde, and acrylonitrile, which contributed 43%, 19%, and 14% to the cumulative risk, respectively. This is the first field study to confirm acrylonitrile as a potential risk driver. Mobile, secondary, industrial, and background sources contributed 57%, 24%, 14%, and 5% of the risk, respectively. The results of this study indicate that southwest Memphis, a region of significant income, racial, and social disparities, is also a region under significant environmental stress compared with surrounding areas and communities.

  17. Exposure information in environmental health research: Current opportunities and future directions for particulate matter, ozone, and toxic air pollutants

    SciTech Connect

    McKone, Thomas E.; Ryan, P. Barry; Ozkaynak, Haluk

    2007-02-01

    Understanding and quantifying outdoor and indoor sources of human exposure are essential but often not adequately addressed in health-effects studies for air pollution. Air pollution epidemiology, risk assessment, health tracking and accountability assessments are examples of health-effects studies that require but often lack adequate exposure information. Recent advances in exposure modeling along with better information on time-activity and exposure factors data provide us with unique opportunities to improve the assignment of exposures for both future and ongoing studies linking air pollution to health impacts. In September 2006, scientists from the US Environmental Protection Agency (EPA) and the Centers for Disease Control and Prevention (CDC) along with scientists from the academic community and state health departments convened a symposium on air pollution exposure and health in order to identify, evaluate, and improve current approaches for linking air pollution exposures to disease. This manuscript presents the key issues, challenges and recommendations identified by the exposure working group, who used cases studies of particulate matter, ozone, and toxic air pollutant exposure to evaluate health-effects for air pollution. One of the over-arching lessons of this workshop is that obtaining better exposure information for these different health-effects studies requires both goal-setting for what is needed and mapping out the transition pathway from current capabilities to meeting these goals. Meeting our long-term goals requires definition of incremental steps that provide useful information for the interim and move us toward our long-term goals. Another over-arching theme among the three different pollutants and the different health study approaches is the need for integration among alternate exposure assessment approaches. For example, different groups may advocate exposure indicators, biomonitoring, mapping methods (GIS), modeling, environmental media

  18. Assessing the toxic effects of ethylene glycol ethers using Quantitative Structure Toxicity Relationship models

    SciTech Connect

    Ruiz, Patricia; Mumtaz, Moiz; Gombar, Vijay

    2011-07-15

    Experimental determination of toxicity profiles consumes a great deal of time, money, and other resources. Consequently, businesses, societies, and regulators strive for reliable alternatives such as Quantitative Structure Toxicity Relationship (QSTR) models to fill gaps in toxicity profiles of compounds of concern to human health. The use of glycol ethers and their health effects have recently attracted the attention of international organizations such as the World Health Organization (WHO). The board members of Concise International Chemical Assessment Documents (CICAD) recently identified inadequate testing as well as gaps in toxicity profiles of ethylene glycol mono-n-alkyl ethers (EGEs). The CICAD board requested the ATSDR Computational Toxicology and Methods Development Laboratory to conduct QSTR assessments of certain specific toxicity endpoints for these chemicals. In order to evaluate the potential health effects of EGEs, CICAD proposed a critical QSTR analysis of the mutagenicity, carcinogenicity, and developmental effects of EGEs and other selected chemicals. We report here results of the application of QSTRs to assess rodent carcinogenicity, mutagenicity, and developmental toxicity of four EGEs: 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, and 2-butoxyethanol and their metabolites. Neither mutagenicity nor carcinogenicity is indicated for the parent compounds, but these compounds are predicted to be developmental toxicants. The predicted toxicity effects were subjected to reverse QSTR (rQSTR) analysis to identify structural attributes that may be the main drivers of the developmental toxicity potential of these compounds.

  19. Evaluation of a possible association of urban air toxics and asthma.

    PubMed Central

    Leikauf, G D; Kline, S; Albert, R E; Baxter, C S; Bernstein, D I; Buncher, C R

    1995-01-01

    The prevalence of asthma, measured either as the frequency of hospital admissions or number of deaths attributed to asthma, has increased over the last 15 to 20 years. Rapid increases in disease prevalence are more likely to be attributable to environmental than genetic factors. Inferring from past associations between air pollution and asthma, it is feasible that changes in the ambient environment could contribute to this increase in morbidity and mortality. Scientific evaluation of the links between air pollution and the exacerbation of asthma is incomplete, however. Currently, criteria pollutants [SOx, NOx, O3, CO, Pb, particulate matter (PM10)] and other risk factors (exposure to environmental tobacco smoke, volatile organic compounds, etc.) are constantly being evaluated as to their possible contributions to this situation. Data from these studies suggest that increases in respiratory disease are associated with exposures to ambient concentrations of particulate and gaseous pollutants. Similarly, exposure to environmental tobacco smoke, also a mixture of particulate and gaseous air toxics, has been associated with an increase in asthma among children. In addition, current associations of adverse health effects with existing pollution measurements are often noted at concentrations below those that produce effects in controlled animal and human exposures to each pollutant alone. These findings imply that adverse responses are augmented when persons are exposed to irritant mixtures of particles and gases and that current measurements of air pollution are, in part, indirect in that the concentrations of criteria pollutants are acting as surrogates of our exposure to a complex mixture. Other irritant air pollutants, including certain urban air toxics, are associated with asthma in occupational settings and may interact with criteria pollutants in ambient air to exacerbate asthma. An evaluation of dose-response information for urban air toxics and biological

  20. Air toxics in coal: Distribution and abundance of selected trace elements in the Powder River Basin

    SciTech Connect

    Crowley, S.S.; Stanton, R.W.

    1994-12-31

    The 1990 Clean Air Act Amendments identified 12 potentially toxic elements, called ``air toxics,`` that may be released during the combustion of coal. The elements identified in the amendments are As, Be, Cd, Cr, Co, Hg, Mn, Ni, Pb, Sb, Se, and U (radionuclides). In this study, the distribution and concentration of these elements were examined, on a whole-coal basis, in samples from two cores of the Wyodak-Anderson coal bed (Paleocene, Tongue River Member of the Fort Union Formation), in the Powder River Basin of Wyoming. The distribution of these elements in the Wyodak-Anderson coal bed is also compared to the distribution of the same elements in a correlative coal bed, the Anderson-Dietz 1 coal bed in the Powder River Basin of Montana.

  1. Asthma symptoms in Hispanic children and daily ambient exposures to toxic and criteria air pollutants.

    PubMed Central

    Delfino, Ralph J; Gong, Henry; Linn, William S; Pellizzari, Edo D; Hu, Ye

    2003-01-01

    Although acute adverse effects on asthma have been frequently found for the U.S. Environmental Protection Agency's principal criteria air pollutants, there is little epidemiologic information on specific hydrocarbons from toxic emission sources. We conducted a panel study of 22 Hispanic children with asthma who were 10-16 years old and living in a Los Angeles community with high traffic density. Subjects filled out symptom diaries daily for up to 3 months (November 1999 through January 2000). Pollutants included ambient hourly values of ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide and 24-hr values of volatile organic compounds (VOCs), particulate matter with aerodynamic diameter < 10 microm (PM10, and elemental carbon (EC) and organic carbon (OC) PM10 fractions. Asthma symptom severity was regressed on pollutants using generalized estimating equations, and peak expiratory flow (PEF) was regressed on pollutants using mixed models. We found positive associations of symptoms with criteria air pollutants (O3, NO2, SO2, PM10), EC-OC, and VOCs (benzene, ethylbenzene, formaldehyde, acetaldehyde, acetone, 1,3-butadiene, tetrachloroethylene, toluene, m,p-xylene, and o-xylene). Selected adjusted odds ratios for bothersome or more severe asthma symptoms from interquartile range increases in pollutants were, for 1.4 ppb 8-hr NO2, 1.27 [95% confidence interval (CI), 1.05-1.54]; 1.00 ppb benzene, 1.23 (95% CI, 1.02-1.48); 3.16 ppb formaldehyde, 1.37 (95% CI, 1.04-1.80); 37 microg/m3 PM10, 1.45 (95% CI, 1.11-1.90); 2.91 microg/m3 EC, 1.85 (95% CI, 1.11-3.08); and 4.64 microg/m3 OC, 1.88 (95% CI, 1.12-3.17). Two-pollutant models of EC or OC with PM10 showed little change in odds ratios for EC (to 1.83) or OC (to 1.89), but PM10 decreased from 1.45 to 1.0. There were no significant associations with PEF. Findings support the view that air toxins in the pollutant mix from traffic and industrial sources may have adverse effects on asthma in children. PMID:12676630

  2. The current practice of health risk assessment: Potential impact on standards for toxic air contaminants

    SciTech Connect

    Paustenbach, D.J.; Jernigan, J.D.; Finley, B.L.; Ripple, S.R.; Keenan, R.E. )

    1990-12-01

    Since the Bhopal incident, the public has placed pressure on regulatory agencies to set community exposure limits for the dozens of chemicals that may be released by manufacturing facilities. More or less objective limits can be established for the vast majority of these chemicals through the use of risk assessment. However, each step of the risk assessment process (i.e., hazard identification, dose-response assessment, exposure assessment, and risk characterization) contains a number of pitfalls that scientists need to avoid to ensure that valid limits are established. For example, in the hazard identification step there has been little discrimination among animal carcinogens with respect to mechanism of action or the epidemiology experience. In the dose-response portion, rarely is the range of plausible estimated risks presented. Physiologically based pharmacokinetic (PB-PK) models should be used to understand the difference between the tissue doses and the administered dose, as well as the difference in target tissue concentrations of the toxicant between rodents and humans. Biologically-based models like the Moolgavkar-Knudson-Venzon (MKV) should be developed and used, when appropriate. The exposure assessment step can be significantly improved by using more sensitive and specific sampling and analytical methods, more accurate exposure parameters, and computer models that can account for complex environmental factors. Whenever possible, model predictions of exposure and uptake should be validated by biological monitoring of exposed persons (urine, blood, adipose) or by field measurements of plants, soil, fish, air, or water. In each portion of an assessment, the weight of evidence approach should be used to identify the most defensible value. 129 refs.

  3. TOWARDS REFINED USE OF TOXICITY DATA IN STATISTICALLY BASED SAR MODELS FOR DEVELOPMENTAL TOXICITY.

    EPA Science Inventory

    In 2003, an International Life Sciences Institute (ILSI) Working Group examined the potential of statistically based structure-activity relationship (SAR) models for use in screening environmental contaminants for possible developmental toxicants.

  4. THE IMPACT OF SHRINKING HANFORD BOUNDARIES ON PERMITS FOR TOXIC AIR POLLUTANT EMISSIONS FROM THE HANFORD 200 WEST AREA

    SciTech Connect

    JOHNSON, R.E.

    2005-11-09

    This presentation (CE-580. Graduate Seminar) presents a brief description of an approach to use a simpler dispersion modeling method (SCREEN3) in conjunction with joint frequency tables for Hanford wind conditions to evaluate the impacts of shrinking the Hanford boundaries on the current permits for facilities in the 200 West Area. To fulfill requirements for the graduate student project (CE-702. Master's Special Problems), this evaluation will be completed and published over the next two years. Air toxic emissions play an important role in environmental quality and require a state approved permit. One example relates to containers or waste that are designated as Transuranic Waste (TRU), which are required to have venting devices due to hydrogen generation. The Washington State Department of Ecology (Ecology) determined that the filters used did not meet the definition of a ''pressure relief device'' and that a permit application would have to be submitted by the Central Waste Complex (CWC) for criteria pollutant and toxic air pollutant (TAP) emissions in accordance with Washington Administrative Code (WAC) 173-400 and 173-460. The permit application submitted in 2000 to Ecology used Industrial Source Code III (ISCIII) dispersion modeling to demonstrate that it was not possible for CWC to release a sufficient quantity of fugitive Toxic Air Pollutant emissions that could exceed the Acceptable Source Impact Levels (ASILs) at the Hanford Site Boundary. The modeled emission rates were based on the diurnal breathing in and out through the vented drums (approximately 20% of the drums), using published vapor pressure, molecular weight, and specific gravity data for all 600+ compounds, with a conservative estimate of one exchange volume per day (208 liters per drum). Two permit applications were submitted also to Ecology for the Waste Receiving and Processing Facility and the T Plant Complex. Both permit applications were based on the Central Waste Complex approach, and

  5. “A Reduced-form Model to Estimate Near-road Air Quality for Communities: the Community Line Source modeling system (C-LINE)”

    EPA Science Inventory

    The paper presents the Community Line Source (C-LINE) modeling system that estimates toxic air pollutant (air toxics) concentration gradients within 500 meters of busy roadways for community-sized areas on the order of 100 km2. C-LINE accesses publicly available datasets with nat...

  6. Major ion toxicity of six produced waters to three freshwater species: Application of ion toxicity models and TIE procedures

    SciTech Connect

    Tietge, J.E.; Hockett, J.R.; Evans, J.M.

    1997-10-01

    Previous research to characterize the acute toxicity of major ions to freshwater organisms resulted in the development of statistical toxicity models for three freshwater species (Ceriodaphnia dubia, Pimephales promelas, and Daphnia magna). These ion toxicity models estimate the toxicity of seven major ions utilizing logistic regression. In this study, the ion toxicity models were used in conjunction with Phase 1 toxicity identification evaluation (TIE) procedures to evaluate the contribution of major ion toxicity to the total toxicity of six produced water samples ranging in total salinity from 1.7 to 58.1 g/L. Initial toxicities of all six samples were compared to the model predictions. Four produced waters were found to have toxicity consistent with toxicity attributable to major ion concentrations only. Two produced waters were found to exhibit more toxicity than expected from ion concentrations alone. These samples were subjected to Phase 1 TIE procedures. Toxicities were reduced by specific Phase 1 TIE manipulations to those predicted by the ion toxicity models. Mock effluents were used to verify the results. The combination of the ion toxicity models with Phase 1 TIE procedures successfully quantified the toxicity due to major ions in six produced water samples.

  7. Physical modeling of air flow during air sparging remediation.

    PubMed

    Hu, Liming; Wu, Xiaofeng; Liu, Yan; Meegoda, Jay N; Gao, Shengyan

    2010-05-15

    Air sparging (AS) is one of the most efficient techniques for remediating saturated soils and groundwater contaminated with volatile organic compounds. A series of physical modeling tests for different sizes of porous media under varied injection pressure were conducted to investigate the effect of particle size and air injection pressure on size and shape of the zone of influence (ZOI). The test results show that ZOI can be expressed by two components: the horizontal expansion due to pneumatic fracture or preferential intrusion around the injection point and the angle of ZOI which is the angle between the vertical line and the boundary of ZOI. There exists a limited angle of ZOI for each type of porous media. The measured minimum and maximum air injection pressures in 1g tests are compared with corresponding theoretical values, and it is found that the measured minimum injection pressure is slightly lower than the theoretical value, while the measured maximum injection pressure is much higher than the theoretical maximum injection pressure. Centrifugal test results confirmed nonapplicability of theoretical maximum injection pressure to air sparging design. All of the above provide valuable information for design and theoretical modeling of air sparging for groundwater remediation.

  8. Simulation model air-to-air plate heat exchanger

    SciTech Connect

    Wetter, Michael

    1999-01-01

    A simple simulation model of an air-to-air plate heat exchanger is presented. The model belongs to a collection of simulation models that allows the eflcient computer simulation of heating, ventilation, and air-conditioning (HVAC) systems. The main emphasis of the models is to shorten computation time and to use only input data that are known in the design process of an HVAC system. The target of the models is to describe the behavior of HVAC components in the part-load operation mode, which is becoming increasingly important in energy eficient HVAC systems. The models are intended to be used for yearly energy calculations or load calculations with time steps of about 10 minutes or larger. Short- time dynamic effects, which are of interest for different aspects of control theory, are neglected. The part-load behavior is expressed in terms of the nominal condition and the dimensionless variation of the heat transfer with change of mass flow and temperature. The effectiveness- NTU relations are used to parametrize the convective heat transfer at nominal conditions and to compute the part-load condition. If the heat transfer coefficients on the two exchanger sides are not equal (i. e. due to partial bypassing of air), their ratio can be easily calculated and set as a parameter. The model is static and uses explicit equations only. The explicit model formulation ensures short computation time and numerical stability, which allows using the model with sophisticated engineering methods like automatic system optimization. This paper fully outlines the algorithm description and its simplifications. It is not tailored for any particular simulation program to ensure easy implementation in any simulation program.

  9. An evaluation of EPA’s National-Scale Air Toxics Assessment (NATA): Comparison with benzene measurements in Detroit, Michigan

    NASA Astrophysics Data System (ADS)

    George, Barbara Jane; Schultz, Bradley D.; Palma, Ted; Vette, Alan F.; Whitaker, Donald A.; Williams, Ronald W.

    2011-06-01

    The U.S. EPA periodically evaluates ambient concentrations, human exposures, and health risks for 180 hazardous air pollutants plus diesel particulate matter using modeled estimates from the National-Scale Air Toxics Assessment (NATA). NATA publishes estimates at the spatial resolution of U.S. Census tracts, which are subdivisions of a county. These local scale, model-predicted estimates from NATA are used extensively in community-based assessments; however, evaluation of NATA's ambient concentrations and human exposure estimates against measurement data has been limited to date. This paper compares modeled annual average benzene results from the 2002 NATA with measured results from the 2004 to 2007 Detroit Exposure and Aerosol Research Study (DEARS) as a case study of the quality of NATA results. NATA model estimates support community-scale characterization and assessment. Benzene is particularly important as it was estimated by the 2002 NATA as the largest single air toxic pollutant in terms of cancer risk in the U.S. We found that the average ambient concentrations of benzene predicted by NATA were within 5 percent, on average, of the 24-h integrated average ambient concentrations measured in DEARS. The NATA human exposure estimates, which include only outdoor sources for benzene, were, on average, approximately half the measured breathing zone concentrations from DEARS. Our analyses support that the factors driving higher DEARS personal benzene concentrations relative to the NATA predicted exposure values are likely due, at least in part, to indoor sources. This work points to further community-scale modeling research to improve characterizations and assessments of human exposures.

  10. Sublethal toxicant effects with dynamic energy budget theory: model formulation.

    PubMed

    Muller, Erik B; Nisbet, Roger M; Berkley, Heather A

    2010-01-01

    We develop and test a general modeling framework to describe the sublethal effects of pollutants by adding toxicity modules to an established dynamic energy budget (DEB) model. The DEB model describes the rates of energy acquisition and expenditure by individual organisms; the toxicity modules describe how toxicants affect these rates by changing the value of one or more DEB parameters, notably the parameters quantifying the rates of feeding and maintenance. We investigate four toxicity modules that assume: (1) effects on feeding only; (2) effects on maintenance only; (3) effects on feeding and maintenance with similar values for the toxicity parameters; and (4) effects on feeding and maintenance with different values for the toxicity parameters. We test the toxicity modules by fitting each to published data on feeding, respiration, growth and reproduction. Among the pollutants tested are metals (mercury and copper) and various organic compounds (chlorophenols, toluene, polycyclic aromatic hydrocarbons, tetradifon and pyridine); organisms include mussels, oysters, earthworms, water fleas and zebrafish. In most cases, the data sets could be adequately described with any of the toxicity modules, and no single module gave superior fits to all data sets. We therefore propose that for many applications, it is reasonable to use the most general and parameter sparse module, i.e. module 3 that assumes similar effects on feeding and maintenance, as a default. For one example (water fleas), we use parameter estimates to calculate the impact of food availability and toxicant levels on the long term population growth rate. PMID:19633955

  11. Assessing Reproductive Toxicity of Two Environmental Toxicants with a Novel in vitro Human Spermatogenic Model

    PubMed Central

    Easley, Charles A.; Bradner, Joshua M.; Moser, Amber; Rickman, Chelsea A.; McEachin, Zachary T.; Merritt, Megan M.; Hansen, Jason M.; Caudle, W. Michael

    2015-01-01

    Environmental influences and insults by reproductive toxicant exposure can lead to impaired spermatogenesis or infertility. Understanding how toxicants disrupt spermatogenesis is critical for determining how environmental factors contribute to impaired fertility. While current animal models are available, understanding of the reproductive toxic effects on human fertility requires a more robust model system. We recently demonstrated that human pluripotent stem cells can differentiate into spermatogonial stem cells/spermatogonia, primary and secondary spermatocytes, and haploid spermatids; a model that mimics many aspects of human spermatogenesis. Here, using this model system, we examine the effects of 2-bromopropane (2-BP) and 1–2, Dibromo-3-chloropropane (DBCP) on in vitro human spermatogenesis. 2-BP and DBCP are non-endocrine disrupting toxicants that are known to impact male fertility. We show that acute treatment with either 2-BP or DBCP induces a reduction in germ cell viability through apoptosis. 2-BP and DBCP affect viability of different cell populations as 2-BP primarily reduces spermatocyte viability whereas DBCP exerts a much greater effect on spermatogonia. Acute treatment with 2-BP or DBCP also reduces the percentage of haploid spermatids. Both 2-BP and DBCP induce reactive oxygen species (ROS) formation leading to an oxidized cellular environment. Taken together, these results suggest that acute exposure with 2-BP or DBCP causes human germ cell death in vitro by inducing ROS formation. This system represents a unique platform for assessing human reproductive toxicity potential of various environmental toxicants in a rapid, efficient, and unbiased format. PMID:25863443

  12. Evaluation of a possible association of urban air toxics and asthma

    SciTech Connect

    Leikauf, G.D.; Kline, S.; Albert, R.E.; Baxter, C.S.

    1995-09-01

    The prevalence of asthma, measured either as the frequency of hospital admission or number of deaths attributed to asthma, has increased over the last 15 to 20 years. Rapid increases in disease prevalence are more likely to be attributable to environmental than genetic factors. inferring from past associations between air pollution and asthma, it is feasible that changes in the ambient environment could contribute to this increase in morbidity and mortality. Scientific evaluation of the links between air pollution and the exacerbation of asthma is incomplete, however. Currently, criteria pollutants [SO{sub x}NO{sub x}, O{sub 3}, CO, Pb, particulate matter (PM{sub 10})] and other risk factors (exposure to environmental tobacco smoke, volatile organic compounds, etc.) are constantly being evaluated as to their possible contributions to this situation. Data from these studies suggest that increases in respiratory disease are associated with exposures to ambient concentrations of particulate and gaseous pollutants. Similarly, exposure to environmental tobacco smoke, also a mixture of particles and gases and that current measurements of air pollution are, in part, indirect in that the concentrations of criteria pollutants are acting as surrogates of our exposure to a complex mixture. Other irritant air pollutants, including certain urban air toxics, are associated with asthma in occupational settings and may interact with criteria pollutants in ambient air to exacerbate asthma. 179 refs., 2 figs., 18 tabs.

  13. Developing an Experimental Model of Vascular Toxicity in Embryonic Zebrafish

    EPA Science Inventory

    Developing an Experimental Model of Vascular Toxicity in Embryonic Zebrafish Tamara Tal, Integrated Systems Toxicology Division, U.S. EPA Background: There are tens of thousands of chemicals that have yet to be fully evaluated for their toxicity by validated in vivo testing ...

  14. NASA/Air Force Cost Model: NAFCOM

    NASA Technical Reports Server (NTRS)

    Winn, Sharon D.; Hamcher, John W. (Technical Monitor)

    2002-01-01

    The NASA/Air Force Cost Model (NAFCOM) is a parametric estimating tool for space hardware. It is based on historical NASA and Air Force space projects and is primarily used in the very early phases of a development project. NAFCOM can be used at the subsystem or component levels.

  15. Virtual Embryo: Systems Modeling in Developmental Toxicity

    EPA Science Inventory

    High-throughput and high-content screening (HTS-HCS) studies are providing a rich source of data that can be applied to in vitro profiling of chemical compounds for biological activity and potential toxicity. EPA’s ToxCast™ project, and the broader Tox21 consortium, in addition t...

  16. The CAESAR models for developmental toxicity

    EPA Science Inventory

    The new REACH legislation requires assessment of a high number of chemicals in the European market for several endpoints. Developmental Toxicity results amongst the most difficult endpoint to assess, due to the complexity, length and costs of experiments. Following the encouragem...

  17. Portable air pollution control equipment for the control of toxic particulate emissions

    SciTech Connect

    Chaurushia, A.; Odabashian, S.; Busch, E.

    1997-12-31

    Chromium VI (Cr VI) has been identified by the environmental regulatory agencies as a potent carcinogen among eleven heavy metals. A threshold level of 0.0001 lb/year for Cr VI emissions has been established by the California Air Resources Board for reporting under Assembly Bill 2588. A need for an innovative control technology to reduce fugitive emissions of Cr VI was identified during the Air Toxic Emissions Reduction Program at Northrop Grumman Military Aircraft Systems Division (NGMASD). NGMASD operates an aircraft assembly facility in El Segundo, CA. Nearly all of the aircraft components are coated with a protective coating (primer) prior to assembly. The primer has Cr VI as a component for its excellent corrosion resistance property. The complex assembly process requires fasteners which also need primer coating. Therefore, NGMASD utilizes High Volume Low Pressure (HVLP) guns for the touch-up spray coating operations. During the touch-up spray coating operations, Cr VI particles are atomized and transferred to the aircraft surface. The South Coast Air Quality Management District (SCAQMD) has determined that the HVLP gun transfers 65% of the paint particles onto the substrate and the remaining 35% are emitted as an overspray if air pollution controls are not applied. NGMASD has developed the Portable Air Pollution Control Equipment (PAPCE) to capture and control the overspray in order to reduce fugitive Cr VI emissions from the touch-up spray coating operations. A source test was performed per SCAQMD guidelines and the final report has been approved by the SCAQMD.

  18. Air Tightness of US Homes: Model Development

    SciTech Connect

    Sherman, Max H.

    2006-05-01

    Air tightness is an important property of building envelopes. It is a key factor in determining infiltration and related wall-performance properties such as indoor air quality, maintainability and moisture balance. Air leakage in U.S. houses consumes roughly 1/3 of the HVAC energy but provides most of the ventilation used to control IAQ. The Lawrence Berkeley National Laboratory has been gathering residential air leakage data from many sources and now has a database of more than 100,000 raw measurements. This paper uses that database to develop a model for estimating air leakage as a function of climate, building age, floor area, building height, floor type, energy-efficiency and low-income designations. The model developed can be used to estimate the leakage distribution of populations of houses.

  19. Mobile Laboratory Measurements of On-Road Vehicle Air Toxics Emissions in Mexico City

    NASA Astrophysics Data System (ADS)

    Kolb, C. E.; Herndon, S. C.; Zavala, M.; Knighton, B.; Marr, L. C.; Zahniser, M. S.; Jayne, J. T.; Shorter, J. H.; Onasch, T. B.; Canagaratna, M. R.; Worsnop, D. R.; Molina, L. T.; Molina, M. J.

    2004-12-01

    The direct emission of toxic organic pollutants from mobile sources is an issue of growing concern. The U.S. Environmental Protection Agency (EPA) and the Federal Highway Administration (FHWA) have identified formaldehyde, acetaldehyde, benzene, acrolein, 1.3 butadiene, and diesel particulate matter (PM), including associated organic compounds, as mobile emissions of priority concern. Real-time trace gas and fine PM sensors deployed on the Aerodyne Research Mobile Laboratory have been used to characterize both fleet average and individual vehicle class on-road emissions of formaldehyde, acetaldehyde, benzene, and diesel particulate matter (PM), including associated organic compounds in the Mexico City Metropolitan Area (MCMA). Data for these air toxics emissions will be reviewed and compared to similar data taken in Boston and New York City, where available. The prospects for future on-road real-time monitoring of acroleinand1.3 butadiene will be discussed.

  20. Stability of air toxic gases listed in Title III Clean Air Act Amendments

    SciTech Connect

    Jayanty, R.K.M.; Jaffe, L.B.; Albritton, J.R.; Jackson, M.D.; Midgett, M.R.

    1992-01-01

    A repository of 59 organic compounds has been established by the U.S. Environmental Protection Agency (EPA) for use as gas standards in performance audits during field validation of emission concentrations from stationary sources. These compounds are listed in Title III of the 1990 Clean Air Act Amendment. The compounds are prepared in compressed gas cylinders and recyclable aluminum containers. Three concentration ranges were selected: low (20 to 200 ppb), mid-level (0.5 to 5 ppm), and high (5 to 50 ppm). The recyclable aluminum containers were only prepared in the low range, and pressures were generally below 400 psig. The compressed gas cylinders contained pressures up to 2000 psig. In this program to ensure that the concentration of each gas standard had not changed, each standard was analyzed periodically for stability. The gas mixtures were analyzed by the manufacturer before shipment. They were then analyzed upon receipt, and reanalyzed periodically to determine any change in concentration. The stability data obtained to date indicates that many compounds are stable in the compressed gas cylinders; however, some of the compounds in the recyclable containers are not stable.

  1. INDOOR AIR QUALITY MODELING (CHAPTER 58)

    EPA Science Inventory

    The chapter discussses indoor air quality (IAQ) modeling. Such modeling provides a way to investigate many IAQ problems without the expense of large field experiments. Where experiments are planned, IAQ models can be used to help design experiments by providing information on exp...

  2. New approaches to toxicity: a seven-gas predictive model and toxicant suppressants.

    PubMed

    Levin, B C

    1997-11-01

    Two new research approaches in combustion toxicology are: 1. the prediction of smoke toxicity from mathematical equations, which are empirically derived from, experiments on the toxicological interactions of complex fire gas mixtures and 2. the use of toxicant suppressants in materials or products to prevent the formation of toxic combustion products. The predictive approach consists of burning materials using a bench-scale method that simulates realistic fire conditions, measuring the concentrations of the primary fire gases--CO, CO2, low O2, HCN, HCl, HBr, and NO2--and predicting the toxicity of the smoke using either the 6- or 7-gas N-Gas Model. These models are based on the results of toxicological studies of these primary gases as individual gases and as complex mixtures. The predicted toxic potency is checked with a small number of animal (Fischer 344 male rats) tests to assure that an unanticipated toxic gas is not generated or an unexpected synergistic or antagonistic effect has not occurred. The results indicate if the smoke from a material or product is extremely toxic (based on mass consumed at the predicted toxic level) or unusually toxic (based on the gases deemed responsible). The predictions based on bench-scale laboratory tests have been validated with full-scale room burns of a limited number of materials of widely differing characteristics chosen to challenge the system. The advantages of this new approach are 1. the number of test animals is minimized by predicting the toxic potency from the chemical analysis of the smoke, 2. smoke may be produced under conditions that simulate the fire scenario of concern, 3. fewer tests are needed, thereby reducing the overall cost of the testing and 4, information is obtained on both the toxic potency of the smoke and the responsible gases. The N-Gas Models have been developed into the N-Gas Method (described in this paper) and these results have been used in computations of fire hazard. The 6-Gas Model is now

  3. Polychlorinated naphthalenes in the air over the equatorial Indian Ocean: Occurrence, potential sources, and toxicity.

    PubMed

    Huang, Yumei; Li, Jun; Xu, Yue; Xu, Weihai; Zhong, Guangcai; Liu, Xiang; Zhang, Gan

    2016-06-15

    Monitoring of marine polychlorinated naphthalenes (PCNs) is crucial, as they are considered persistent organic pollutants (POPs) by the Stockholm Convention. Data on PCNs in marine environment are scarce. In this study, 19 air samples were collected during a cruise in the equatorial Indian Ocean on board the Chinese research vessel Shiyan I from 4/2011 to 5/2011. PCN concentration of these air samples ranged from 0.033 to 2.56pgm(-3), with an average of 0.518pgm(-3), equal to or lower than the values reported for other oceans, seas, and lakes worldwide. Tri- and tetra-CNs were the main homologues in most samples. Reemission of Halowax mixtures and incineration processes were the major sources of atmospheric PCNs in the study area. The PCN-corresponding toxic equivalency values ranged from 0 to 0.190fgm(-3) (average: 0.038fgm(-3)), falling in the low end of global range.

  4. A review of toxicity models for realistic atmospheric applications

    NASA Astrophysics Data System (ADS)

    Gunatilaka, Ajith; Skvortsov, Alex; Gailis, Ralph

    2014-02-01

    There are many applications that need to study human health effects caused by exposure to toxic chemicals. Risk analysis for industrial sites, study of population health impacts of atmospheric pollutants, and operations research for assessing the potential impacts of chemical releases in military contexts are some examples. Because of safety risks and the high cost of field trials involving hazardous chemical releases, computer simulations are widely used for such studies. Modelling of atmospheric transport and dispersion of chemicals released into the atmosphere to determine the toxic chemical concentrations to which individuals will be exposed is one main component of these simulations, and there are well established atmospheric dispersion models for this purpose. Estimating the human health effects caused by the exposure to these predicted toxic chemical concentrations is the other main component. A number of different toxicity models for assessing the health effects of toxic chemical exposure are found in the literature. Because these different models have been developed based on different assumptions about the plume characteristics, chemical properties, and physiological response, there is a need to review and compare these models to understand their applicability. This paper reviews several toxicity models described in the literature. The paper also presents results of applying different toxicity models to simulated concentration time series data. These results show that the use of ensemble mean concentrations, which are what atmospheric dispersion models typically provide, to estimate human health effects of exposure to hazardous chemical releases may underestimate their impact when toxic exponent, n, of the chemical is greater than one; the opposite phenomenon appears to hold when n < 1. The results also show that some toxicity models that disregard biological recovery processes may predict greater toxicity than the explicitly parameterised models. Despite

  5. Zebrafish models for assessing developmental and reproductive toxicity.

    PubMed

    He, Jian-Hui; Gao, Ji-Min; Huang, Chang-Jiang; Li, Chun-Qi

    2014-01-01

    The zebrafish is increasingly used as a vertebrate animal model for in vivo drug discovery and for assessing chemical toxicity and safety. Numerous studies have confirmed that zebrafish and mammals are similar in their physiology, development, metabolism and pathways, and that zebrafish responses to toxic substances are highly predictive of mammalian responses. Developmental and reproductive toxicity assessments are an important part of new drug safety profiling. A significant number of drug candidates have failed in preclinical tests due to their adverse effect on development and reproductivity. Compared to conventional mammal testing, zebrafish testing for assessing developmental and reproductive toxicity offers several compelling experimental advantages, including transparency of embryo and larva, higher throughput, shorter test period, lower cost, smaller amount of compound required, easier manipulation and direct compound delivery. Toxicity and safety assessments using zebrafish have also been accepted by the FDA and EMEA for investigative new drug (IND) approval.

  6. Projections of air toxic emissions from coal-fired utility combustion: Input for hazardous air pollutant regulators

    SciTech Connect

    Szpunar, C.B.

    1993-08-01

    The US Environmental Protection Agency (EPA) is required by the 1990 CAAA to promulgate rules for all ``major`` sources of any of these HAPs. According to the HAPs section of the new Title III, any stationary source emitting 10 tons per year (TPY) of one HAP or 25 TPY of a combination of HAPs will be considered and designated a major source. In contrast to the original National Emission Standards for Hazardous Air Pollutants (NESHAP), which were designed to protect public health to ``an ample margin of safety,`` the new Title III, in its first phase, will regulate by industrial category those sources emitting HAPs in excess of the 10/25-TPY threshold levels, regardless of health risks. The trace elements normally associated with coal mineral matter and the various compounds formed during coal combustion have the potential to produce hazardous air toxic emissions from coal-fired electric utilities. Under Title III, the EPA is required to perform certain studies, prior to any regulation of electric utilities; these studies are currently underway. Also, the US Department of Energy (DOE) maintains a vested interest in addressing those energy policy questions affecting electric utility generation, coal mining, and steel producing critical to this country`s economic well-being, where balancing the costs to the producers and users of energy with the benefits of environmental protection to the workers and the general populace remains of significant concern.

  7. Biomarkers for assessing body burden from exposure to toxic air pollutants

    SciTech Connect

    Gordon, S.M.; O'Neill, H.J.; Moschandreas, D.J. ); Lewis, R.G.; Wilson, N.K. )

    1988-09-01

    The body burden of airborne toxic chemicals resulting from all routes of human exposure cannot be determined by traditional techniques, which only measure the concentrations of these chemicals in air. Human exposure has been related to biological endpoints in several studies using biochemical markers. It may be possible to relate human exposure to breath concentrations, biological endpoints, and ultimately body burden, using noninvasive techniques (breath and urine analysis). Preliminary chamber studies in their laboratory have shown that subjects exposed to selected air pollutants at near-normal ambient levels eliminate them in breath at measurable decay rates. This study seeks to determine expired-air decay rates for selected air pollutants and their blood/breath partition coefficients. Such data could lead to correlations with the primary biomarkers directly related to biological endpoints (e.g., DNA or protein adducts, glutathione conjugates, chromosomal damage, immune function impairment). If an association can be established between noninvasive data and primary biomarkers, then an integrated approach should be possible for measuring biological endpoints noninvasively by monitoring human expired breath or urine.

  8. Model validation in aquatic toxicity testing: implications for regulatory practice.

    PubMed

    McCarty, L S

    2012-08-01

    Toxicity test validity is contingent on whether models and assumptions are appropriate and sufficient. A quality control evaluation of the acute toxicity testing protocol using the US. EPA fathead minnow database focused around three key assumptions that ensure results represent valid toxicological metrics: 1, it must be possible to estimate steady-state LC50s; 2, LC50s should occur at equivalent exposure durations; 3, all substantive toxicity modifying factors should be adequately controlled. About 8% of the tests failed the first assumption and are invalid and unusable. Examination of remaining data indicated variance from unquantified effects of toxicity modifying factors remained in LC50s, thereby failing assumption three. Such flaws in toxicity data generated via recommended LC50 testing protocols means resultant data do not represent consistent, comparable measures of relative toxicity. Current regulations employing LC50 testing data are acceptable due to the use of semiquantitative, policy-driven development guidance that considers such data uncertainty. Quantitative applications such as QSARs, mixture toxicity, and regulatory chemical grouping can be compromised. These validation failures justify a formal quality control review of the LC50 toxicity testing protocol. Interim improvements in the design, execution, interpretation, and regulatory applications of LC50 and related protocols using exposure-based dose surrogates are warranted.

  9. Toxicity of silver nanoparticles in zebrafish models

    NASA Astrophysics Data System (ADS)

    Asharani, P. V.; Lian Wu, Yi; Gong, Zhiyuan; Valiyaveettil, Suresh

    2008-06-01

    This study was initiated to enhance our insight on the health and environmental impact of silver nanoparticles (Ag-np). Using starch and bovine serum albumin (BSA) as capping agents, silver nanoparticles were synthesized to study their deleterious effects and distribution pattern in zebrafish embryos (Danio rerio). Toxicological endpoints like mortality, hatching, pericardial edema and heart rate were recorded. A concentration-dependent increase in mortality and hatching delay was observed in Ag-np treated embryos. Additionally, nanoparticle treatments resulted in concentration-dependent toxicity, typified by phenotypes that had abnormal body axes, twisted notochord, slow blood flow, pericardial edema and cardiac arrhythmia. Ag+ ions and stabilizing agents showed no significant defects in developing embryos. Transmission electron microscopy (TEM) of the embryos demonstrated that nanoparticles were distributed in the brain, heart, yolk and blood of embryos as evident from the electron-dispersive x-ray analysis (EDS). Furthermore, the acridine orange staining showed an increased apoptosis in Ag-np treated embryos. These results suggest that silver nanoparticles induce a dose-dependent toxicity in embryos, which hinders normal development.

  10. Sampling of air streams and incorporation of samples in the Microtox{trademark} toxicity testing system

    SciTech Connect

    Kleinheinz, G.T.; St. John, W.P.

    1997-10-01

    A study was conducted to develop a rapid and reliable method for the collection and incorporation of biofiltration air samples containing volatile organic compounds (VOCs) into the Microtox toxicity testing system. To date, no method exists for this type of assay. A constant stream of VOCs was generated by air stripping compounds from a complex mixture of petroleum hydrocarbons (PHCs). Samples were collected on coconut charcoal ORBO tubes and the VOCs extracted with methylene chloride. The compounds extracted were then solvent exchanged into dimethyl sulfoxide (DMSO) under gaseous nitrogen. The resulting DMSO extract was directly incorporated into the Microtox toxicity testing system. In order to determine the efficiency of the solvent exchange, the VOCs in the DMSO extract were then extracted into hexane and subsequently analyzed using gas chromatography (GC) with a flame ionization detector (FID). It was determined that all but the most volatile VOCs could be effectively transferred from the ORBO tubes to DMSO for Microtox testing. Potential trace amounts of residual methylene chloride in the DMSO extracts showed no adverse effects in the Microtox system when compared to control samples.

  11. Toxicity Assessment of Air-delivered Particle-bound Polybrominated Diphenyl Ethers

    PubMed Central

    Kim, Jong Sung; Klösener, Johannes; Flor, Susanne; Peters, Thomas M.; Ludewig, Gabriele; Thorne, Peter S.; Robertson, Larry W.; Luthe, Gregor

    2014-01-01

    Human exposure to polybrominated diphenyl ether (PBDE) can occur via ingestion of indoor dust, inhalation of PBDE-contaminated air and dust-bound PBDEs. However, few studies have examined the pulmonary toxicity of particle-bound PBDEs, mainly due to the lack of an appropriate particle-cell exposure system. In this study we developed an in vitro exposure system capable of generating particle-bound PBDEs mimicking dusts containing PBDE congeners (BDEs 35, 47, 99) and delivering them directly onto lung cells grown at an air-liquid interface (ALI). The silica particles and particle-coated with PBDEs ranged in diameter from 4.3 to 4.5 μm and were delivered to cells with no apparent aggregation. This experimental set up demonstrated high reproducibility and sensitivity for dosing control and distribution of particles. ALI exposure of cells to PBDE-bound particles significantly decreased cell viability and induced reactive oxygen species generation in A549 and NCI-H358 cells. In male Sprague-Dawley rats exposed via intratracheal insufflation (0.6 mg/rat), particle-bound PBDE exposures induced inflammatory responses with increased recruitment of neutrophils to the lungs compared to sham-exposed rats. The present study clearly indicates the potential of our exposure system for studying the toxicity of particle-bound compounds. PMID:24451063

  12. Uncertainty for data with non-detects: Air toxic emissions from combustion

    SciTech Connect

    Zhao, Y.C.; Frey, H.C.

    2006-12-15

    Air toxic emission factor datasets often contain one or more points below a single or multiple detection limits and such datasets are referred to as 'censored.' Conventional methods used to deal with censored datasets include removing non-detects, replacing the censored points with zero, half of the detection limit, or the detection limit. However, the estimated means of the censored dataset by conventional methods are usually biased. Maximum likelihood estimation (MLE) and bootstrap simulation have been demonstrated as a statistically robust method to quantify variability and uncertainty of censored datasets and can provide asymptotically unbiased mean estimates. The MLE/bootstrap method is applied to 16 cases of censored air toxic emission factors, including benzene, formaldehyde, benzo(a)pyrene, mercury, arsenic, cadmium, total chromium, chromium VI and lead from coal, fuel oil, and/or wood waste external combustion sources. The proportion of censored values in the emission factor data ranges from 4 to 80%. Key factors that influence the estimated uncertainty in the mean of censored data are sample size and inter-unit variability. The largest range of uncertainty in the mean was obtained for the external coal combustion benzene emission factor, with 95 confidence interval of the mean equal to minus 93 to plus 411%.

  13. Assessment and prediction of air quality using fuzzy logic and autoregressive models

    NASA Astrophysics Data System (ADS)

    Carbajal-Hernández, José Juan; Sánchez-Fernández, Luis P.; Carrasco-Ochoa, Jesús A.; Martínez-Trinidad, José Fco.

    2012-12-01

    In recent years, artificial intelligence methods have been used for the treatment of environmental problems. This work, presents two models for assessment and prediction of air quality. First, we develop a new computational model for air quality assessment in order to evaluate toxic compounds that can harm sensitive people in urban areas, affecting their normal activities. In this model we propose to use a Sigma operator to statistically asses air quality parameters using their historical data information and determining their negative impact in air quality based on toxicity limits, frequency average and deviations of toxicological tests. We also introduce a fuzzy inference system to perform parameter classification using a reasoning process and integrating them in an air quality index describing the pollution levels in five stages: excellent, good, regular, bad and danger, respectively. The second model proposed in this work predicts air quality concentrations using an autoregressive model, providing a predicted air quality index based on the fuzzy inference system previously developed. Using data from Mexico City Atmospheric Monitoring System, we perform a comparison among air quality indices developed for environmental agencies and similar models. Our results show that our models are an appropriate tool for assessing site pollution and for providing guidance to improve contingency actions in urban areas.

  14. Ranking of aquatic toxicity of esters modelled by QSAR.

    PubMed

    Papa, Ester; Battaini, Francesca; Gramatica, Paola

    2005-02-01

    Alternative methods like predictions based on Quantitative Structure-Activity Relationships (QSARs) are now accepted to fill data gaps and define priority lists for more expensive and time consuming assessments. A heterogeneous data set of 74 esters was studied for their aquatic toxicity, and available experimental toxicity data on algae, Daphnia and fish were used to develop statistically validated QSAR models, obtained using multiple linear regression (MLR) by the OLS (Ordinary Least Squares) method and GA-VSS (Variable Subset Selection by Genetic Algorithms) to predict missing values. An ESter Aquatic Toxicity INdex (ESATIN) was then obtained by combining, by PCA, experimental and predicted toxicity data, from which model outliers and esters highly influential due to their structure had been eliminated. Finally this integrated aquatic toxicity index, defined by the PC1 score, was modelled using only a few theoretical molecular descriptors. This last QSAR model, statistically validated for its predictive power, could be proposed as a preliminary evaluative method for screening/prioritising esters according to their integrated aquatic toxicity, just starting from their molecular structure.

  15. Modeling monthly mean air temperature for Brazil

    NASA Astrophysics Data System (ADS)

    Alvares, Clayton Alcarde; Stape, José Luiz; Sentelhas, Paulo Cesar; de Moraes Gonçalves, José Leonardo

    2013-08-01

    Air temperature is one of the main weather variables influencing agriculture around the world. Its availability, however, is a concern, mainly in Brazil where the weather stations are more concentrated on the coastal regions of the country. Therefore, the present study had as an objective to develop models for estimating monthly and annual mean air temperature for the Brazilian territory using multiple regression and geographic information system techniques. Temperature data from 2,400 stations distributed across the Brazilian territory were used, 1,800 to develop the equations and 600 for validating them, as well as their geographical coordinates and altitude as independent variables for the models. A total of 39 models were developed, relating the dependent variables maximum, mean, and minimum air temperatures (monthly and annual) to the independent variables latitude, longitude, altitude, and their combinations. All regression models were statistically significant ( α ≤ 0.01). The monthly and annual temperature models presented determination coefficients between 0.54 and 0.96. We obtained an overall spatial correlation higher than 0.9 between the models proposed and the 16 major models already published for some Brazilian regions, considering a total of 3.67 × 108 pixels evaluated. Our national temperature models are recommended to predict air temperature in all Brazilian territories.

  16. Studies with the USF/NASA toxicity screening test method - Effect of air flow and effect of fabric dye

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Lopez, M. T.

    1976-01-01

    One sample each of commercial polyurethane and polychloroprene flexible foams were evaluated using the USF/NASA toxicity screening test method. Air flow rates of 0, 0.16, 16, and 48 ml/sec were used to determine the effect of air flow on relative toxicity. Time to first sign of incapacitation and time to death were substantially reduced with both polyurethane and polychloroprene flexible foams by the introduction of 16 to 48 ml/sec air flow. The relative toxicity rankings of these materials were not altered by changes in air flow. Under these test conditions, the polyurethane foam consistently appeared more toxic than the polychloroprene foam. Samples of six different colors from the same fabric were evaluated separately, using the USF/NASA toxicity screening test method, to determine the effect of fabric dye, if any. The material was an upholstery fabric, consisting of 46 percent cotton, 33 percent wool, and 21 percent nylon. There appeared to be no significant effect of fabric dye on relative toxicity, for this material under these test conditions.

  17. Accuracy of Chronic Aquatic Toxicity Estimates Determined from Acute Toxicity Data and Two Time–Response Models.

    EPA Science Inventory

    Traditionally, chronic toxicity in aquatic organisms and wildlife has been determined from either toxicity test data, acute to chronic ratios, or application of safety factors. A more recent alternative approach has been to estimate chronic toxicity by modeling the time course of...

  18. An exploratory study of ambient air toxics exposure in pregnancy and the risk of neuroblastoma in offspring

    PubMed Central

    Heck, Julia E; Park, Andrew S.; Qiu, Jiaheng; Cockburn, Myles; Ritz, Beate

    2013-01-01

    Little is known about the etiology of neuroblastoma, the most common cancer in infancy. In this study, we examined maternal exposure to ambient air toxics in pregnancy in relation to neuroblastoma in the child. We ascertained all cases of neuroblastoma listed in the California Cancer Registry 1990-2007 that could be linked to a California birth certificate, and controls were selected at random from California birth records. Average air toxics exposures during pregnancy were determined based upon measures from community-based air pollution monitors. The study included 75 cases and 14,602 controls who lived with 5 kilometers of an air pollution monitor, and we additionally examined results for those living within a smaller radius around the monitor (2.5 km). Logistic regression was used to determine the risk of neuroblastoma with one interquartile range increase in air toxic exposure. Neuroblastoma risk was increased with higher maternal exposure to carbon tetrachloride (OR=2.65, 95%CI 1.07, 6.53) and polycyclic aromatic hydrocarbons (OR=1.39, 95%CI 1.05, 1.84), particularly indeno(1,2,3-cd)pyrene and dibenz(a,h)anthracene. Hexavalent chromium was associated with neuroblastoma at the 5 km distance (OR=1.32, 95%CI 1.00, 1.74) but not at the 2.5 km distance. This is one of the first studies to report associations between neuroblastoma and these air toxics. PMID:24139061

  19. Assaying Environmental Nickel Toxicity Using Model Nematodes

    PubMed Central

    Rudel, David; Douglas, Chandler D.; Huffnagle, Ian M.; Besser, John M.; Ingersoll, Christopher G.

    2013-01-01

    Although nickel exposure results in allergic reactions, respiratory conditions, and cancer in humans and rodents, the ramifications of excess nickel in the environment for animal and human health remain largely undescribed. Nickel and other cationic metals travel through waterways and bind to soils and sediments. To evaluate the potential toxic effects of nickel at environmental contaminant levels (8.9-7,600 µg Ni/g dry weight of sediment and 50-800 µg NiCl2/L of water), we conducted assays using two cosmopolitan nematodes, Caenorhabditis elegans and Pristionchus pacificus. We assayed the effects of both sediment-bound and aqueous nickel upon animal growth, developmental survival, lifespan, and fecundity. Uncontaminated sediments were collected from sites in the Midwestern United States and spiked with a range of nickel concentrations. We found that nickel-spiked sediment substantially impairs both survival from larval to adult stages and adult longevity in a concentration-dependent manner. Further, while aqueous nickel showed no adverse effects on either survivorship or longevity, we observed a significant decrease in fecundity, indicating that aqueous nickel could have a negative impact on nematode physiology. Intriguingly, C. elegans and P. pacificus exhibit similar, but not identical, responses to nickel exposure. Moreover, P. pacificus could be tested successfully in sediments inhospitable to C. elegans. Our results add to a growing body of literature documenting the impact of nickel on animal physiology, and suggest that environmental toxicological studies could gain an advantage by widening their repertoire of nematode species. PMID:24116204

  20. Assaying environmental nickel toxicity using model nematodes

    USGS Publications Warehouse

    Rudel, David; Douglas, Chandler; Huffnagle, Ian; Besser, John M.; Ingersoll, Christopher G.

    2013-01-01

    Although nickel exposure results in allergic reactions, respiratory conditions, and cancer in humans and rodents, the ramifications of excess nickel in the environment for animal and human health remain largely undescribed. Nickel and other cationic metals travel through waterways and bind to soils and sediments. To evaluate the potential toxic effects of nickel at environmental contaminant levels (8.9-7,600 µg Ni/g dry weight of sediment and 50-800 µg NiCl2/L of water), we conducted assays using two cosmopolitan nematodes, Caenorhabditis elegans and Pristionchus pacificus. We assayed the effects of both sediment-bound and aqueous nickel upon animal growth, developmental survival, lifespan, and fecundity. Uncontaminated sediments were collected from sites in the Midwestern United States and spiked with a range of nickel concentrations. We found that nickel-spiked sediment substantially impairs both survival from larval to adult stages and adult longevity in a concentration-dependent manner. Further, while aqueous nickel showed no adverse effects on either survivorship or longevity, we observed a significant decrease in fecundity, indicating that aqueous nickel could have a negative impact on nematode physiology. Intriguingly, C. elegansand P. pacificus exhibit similar, but not identical, responses to nickel exposure. Moreover, P. pacificus could be tested successfully in sediments inhospitable to C. elegans. Our results add to a growing body of literature documenting the impact of nickel on animal physiology, and suggest that environmental toxicological studies could gain an advantage by widening their repertoire of nematode species.

  1. Zebrafish: A complete animal model to enumerate the nanoparticle toxicity.

    PubMed

    Chakraborty, Chiranjib; Sharma, Ashish Ranjan; Sharma, Garima; Lee, Sang-Soo

    2016-01-01

    Presently, nanotechnology is a multi-trillion dollar business sector that covers a wide range of industries, such as medicine, electronics and chemistry. In the current era, the commercial transition of nanotechnology from research level to industrial level is stimulating the world's total economic growth. However, commercialization of nanoparticles might offer possible risks once they are liberated in the environment. In recent years, the use of zebrafish (Danio rerio) as an established animal model system for nanoparticle toxicity assay is growing exponentially. In the current in-depth review, we discuss the recent research approaches employing adult zebrafish and their embryos for nanoparticle toxicity assessment. Different types of parameters are being discussed here which are used to evaluate nanoparticle toxicity such as hatching achievement rate, developmental malformation of organs, damage in gill and skin, abnormal behavior (movement impairment), immunotoxicity, genotoxicity or gene expression, neurotoxicity, endocrine system disruption, reproduction toxicity and finally mortality. Furthermore, we have also highlighted the toxic effect of different nanoparticles such as silver nanoparticle, gold nanoparticle, and metal oxide nanoparticles (TiO2, Al2O3, CuO, NiO and ZnO). At the end, future directions of zebrafish model and relevant assays to study nanoparticle toxicity have also been argued. PMID:27544212

  2. Uncertainty in Regional Air Quality Modeling

    NASA Astrophysics Data System (ADS)

    Digar, Antara

    Effective pollution mitigation is the key to successful air quality management. Although states invest millions of dollars to predict future air quality, the regulatory modeling and analysis process to inform pollution control strategy remains uncertain. Traditionally deterministic ‘bright-line’ tests are applied to evaluate the sufficiency of a control strategy to attain an air quality standard. A critical part of regulatory attainment demonstration is the prediction of future pollutant levels using photochemical air quality models. However, because models are uncertain, they yield a false sense of precision that pollutant response to emission controls is perfectly known and may eventually mislead the selection of control policies. These uncertainties in turn affect the health impact assessment of air pollution control strategies. This thesis explores beyond the conventional practice of deterministic attainment demonstration and presents novel approaches to yield probabilistic representations of pollutant response to emission controls by accounting for uncertainties in regional air quality planning. Computationally-efficient methods are developed and validated to characterize uncertainty in the prediction of secondary pollutant (ozone and particulate matter) sensitivities to precursor emissions in the presence of uncertainties in model assumptions and input parameters. We also introduce impact factors that enable identification of model inputs and scenarios that strongly influence pollutant concentrations and sensitivity to precursor emissions. We demonstrate how these probabilistic approaches could be applied to determine the likelihood that any control measure will yield regulatory attainment, or could be extended to evaluate probabilistic health benefits of emission controls, considering uncertainties in both air quality models and epidemiological concentration-response relationships. Finally, ground-level observations for pollutant (ozone) and precursor

  3. Simulation and modeling for military air operations

    NASA Astrophysics Data System (ADS)

    Kreichauf, Ruth D.; Bedros, Saad; Ateskan, Yusuf; Hespanha, Joao; Kizilocak, Hakan

    2001-09-01

    The Joint Forces Air Component Commander (JFACC) in military air operations controls the allocation of resources (wings, squadrons, air defense systems, AWACS) to different geographical locations in the theater of operations. The JFACC mission is to define a sequence of tasks for the aerospace systems at each location, and providing feedback control for the execution of these tasks in the presence of uncertainties and a hostile enemy. Honeywell Labs has been developing an innovative method for control of military air operations. The novel model predictive control (MPC) method extends the models and optimization algorithms utilized in traditional model predictive control systems. The enhancements include a tasking controller and, in a joint effort with USC, a probabilistic threat/survival map indicating high threat regions for aircraft and suggesting optimal routes to avoid these regions. A simulation/modeling environment using object-oriented methodologies has been developed to serve as an aide to demonstrate the value of MPC and facilitate its development. The simulation/modeling environment is based on an open architecture that enables the integration, evaluation, and implementation of different control approaches. The simulation offers a graphical user interface displaying the battlefield, the control performance, and a probability map displaying high threat regions. This paper describes the features of the different control approaches and their integration into the simulation environment.

  4. Toxicity of Nanoparticles and an Overview of Current Experimental Models

    PubMed Central

    Bahadar, Haji; Maqbool, Faheem; Niaz, Kamal; Abdollahi, Mohammad

    2016-01-01

    Nanotechnology is a rapidly growing field having potential applications in many areas. Nanoparticles (NPs) have been studied for cell toxicity, immunotoxicity, and genotoxicity. Tetrazolium-based assays such as MTT, MTS, and WST-1 are used to determine cell viability. Cell inflammatory response induced by NPs is checked by measuring inflammatory biomarkers, such as IL-8, IL-6, and tumor necrosis factor, using ELISA. Lactate dehydrogenase (LDH) assay is used for cell membrane integrity. Different types of cell cultures, including cancer cell lines have been employed as in vitro toxicity models. It has been generally agreed that NPs interfere with either assay materials or with detection systems. So far, toxicity data generated by employing such models are conflicting and inconsistent. Therefore, on the basis of available experimental models, it may be difficult to judge and list some of the more valuable NPs as more toxic to biological systems and vice versa. Considering the potential applications of NPs in many fields and the growing apprehensions of FDA about the toxic potential of nanoproducts, it is the need of the hour to look for new internationally agreed free of bias toxicological models by focusing more on in vivo studies. PMID:26286636

  5. Modeling population exposures to outdoor sources of hazardous air pollutants.

    PubMed

    Ozkaynak, Halûk; Palma, Ted; Touma, Jawad S; Thurman, James

    2008-01-01

    Accurate assessment of human exposures is an important part of environmental health effects research. However, most air pollution epidemiology studies rely upon imperfect surrogates of personal exposures, such as information based on available central-site outdoor concentration monitoring or modeling data. In this paper, we examine the limitations of using outdoor concentration predictions instead of modeled personal exposures for over 30 gaseous and particulate hazardous air pollutants (HAPs) in the US. The analysis uses the results from an air quality dispersion model (the ASPEN or Assessment System for Population Exposure Nationwide model) and an inhalation exposure model (the HAPEM or Hazardous Air Pollutant Exposure Model, Version 5), applied by the US. Environmental protection Agency during the 1999 National Air Toxic Assessment (NATA) in the US. Our results show that the total predicted chronic exposure concentrations of outdoor HAPs from all sources are lower than the modeled ambient concentrations by about 20% on average for most gaseous HAPs and by about 60% on average for most particulate HAPs (mainly, due to the exclusion of indoor sources from our modeling analysis and lower infiltration of particles indoors). On the other hand, the HAPEM/ASPEN concentration ratio averages for onroad mobile source exposures were found to be greater than 1 (around 1.20) for most mobile-source related HAPs (e.g. 1, 3-butadiene, acetaldehyde, benzene, formaldehyde) reflecting the importance of near-roadway and commuting environments on personal exposures to HAPs. The distribution of the ratios of personal to ambient concentrations was found to be skewed for a number of the VOCs and reactive HAPs associated with major source emissions, indicating the importance of personal mobility factors. We conclude that the increase in personal exposures from the corresponding predicted ambient levels tends to occur near locations where there are either major emission sources of HAPs

  6. Thermal decomposition of captan and formation pathways of toxic air pollutants.

    PubMed

    Chen, Kai; Mackie, John C; Kennedy, Eric M; Dlugogorski, Bogdan Z

    2010-06-01

    This study investigates the thermal decomposition of a widely used fungicide, captan, under gas phase conditions, similar to those occurring in fires, cigarette burning, and combustion of biomass treated or contaminated with pesticides. The laboratory-scale apparatus consisted of a plug flow reactor equipped with sampling trains for gaseous, volatile organic compounds (VOC) and condensed products, with analysis performed by Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS), respectively. Under oxidative conditions, the thermal decomposition of captan generated gaseous pollutants including carbon disulfide, thiophosgene, phosgene, and hydrogen cyanide. The VOC analysis revealed the formation of tetrachloroethylene, hexachloroethane, and benzonitrile. Quantum chemical calculations indicated that captan decomposes unimolecularly, via fission of the C-S bond, with the ensuing radicals reacting with O(2). The results of the present study provide an improved understanding of the formation pathways of toxic air pollutants in the accidental or deliberate combustion of captan.

  7. TOF-SIMS measurements for toxic air pollutants adsorbed on the surface of airborne particles

    NASA Astrophysics Data System (ADS)

    Tomiyasu, Bunbunoshin; Hoshi, Takahiro; Owari, Masanori; Nihei, Yoshimasa

    2003-01-01

    Three kinds of particulate matter were collected: diesel and gasoline exhaust particles emitted directly from exhaust nozzle, and suspended particulate matter (SPM) near the traffic route. Soxhlet extraction was performed on each sample. By gas-chromatograph-mass spectrometer (GC-MS) analysis of these extracts, di-ethyl phthalate and di- n-butyl phthalate were detected from the extract of SPM and diesel exhaust particles (DEPs). Because these phthalates were sometimes suspected as contamination, time-of-flight secondary ion mass spectrometry (TOF-SIMS) measurements were also performed on the samples collected at the same environment. By comparing obtained spectra, it is clear that these environmental endocrine disrupters (EEDs) were adsorbed on DEP surface. Thus, we concluded that the combination of conventional method and TOF-SIMS measurement is one of the most powerful techniques for analyzing the toxic air pollutants adsorbed on SPM surface.

  8. Lifetimes and fates of toxic air contaminants in California's atmosphere, June 1993. Final report

    SciTech Connect

    Atkinson, R.; Arey, J.

    1993-06-01

    The report presents information concerning the nature and rate of removal of toxic air pollutants (TAPs) from the atmosphere and any products formed; it also addresses the formation of possible TAPs in the atmosphere. It contains a comprehensive review of the atmospheric chemistry of di(2-ethylhexyl)phthalate, N-nitrosomorpholine, and dialkylnitrosamines. It also outlines the atmospheric lifetimes of 23 possible TAPs, including: hexachlorobenzene, 1,4-dichlorobenzene, dimethyl sulfate, propylene oxide, chlorobenzene, 2,4,6-trichlorophenol, benxyl chloride, acrylonitrile, toluene diisocyanates, and 1,4-dioxane. It also reviews possible atmospheric formation of TAPs. Acrolein, formaldehyde, acetaldehyde, and PAHs are shown to be present in the atmosphere largely due to atmospheric reactions. Another section describes an investigation of the mutagenicity of products of simulated atmospheric reactions of gasoline and terpenes (emitted from vegetation). These may not be major sources of ambient mutagenicity in California.

  9. Endangered species toxicity extrapolation using ICE models

    EPA Science Inventory

    The National Research Council’s (NRC) report on assessing pesticide risks to threatened and endangered species (T&E) included the recommendation of using interspecies correlation models (ICE) as an alternative to general safety factors for extrapolating across species. ...

  10. EPAs Virtual Embryo: Modeling Developmental Toxicity

    EPA Science Inventory

    Embryogenesis is regulated by concurrent activities of signaling pathways organized into networks that control spatial patterning, molecular clocks, morphogenetic rearrangements and cell differentiation. Quantitative mathematical and computational models are needed to better unde...

  11. Silent Discharge Plasma Technology for the Treatment of Air Toxics and Other Applications

    SciTech Connect

    Rosocha, Louis A.; Chase, Peter J.; Gross, Michael P.

    1998-09-21

    Under this CRADA, the Los Alamos National Laboratory (LANL) and High Mesa Technologies, Inc. (HMT) carried out a joint project on the development of the silent discharge plasma (SDP) technology for the treatment of hazardous air pollutants and other hazardous or toxic chemicals. The project had two major components: a technology-demonstration part and a scale-up and commercialization part. In the first part, a small-scale, mobile SDP plasma processor, which was being developed under a CRADA with the Electric Power Research Institute (EPRI) was the mobile equipment was modified for higher capacity service and employed for an innovative remediation technologies demonstration on soil-vapor extraction off-gases at the McClellan Air Force Base near Sacramento, CA. The performance of the SDP system for the variety of volatile organic compounds (VOCs) encountered at the McClellan site was sufficiently promising to the project HMT and LANL worked together to formulate a scale-up strategy and commercialization/manufacturing plan, and to design a prototype scaled-up SDP unit. HMT and LANL are now in the final stages of completing a licensing agreement for the technology and HMT is in the process of raising funds to engineer and manufacture commercial prototype SDP equipment focused on stack-gas emissions control and environmental remediation. HMT, in collaboration with another Northern New Mexico business, Coyote Aerospace, has also been successful in receiving a Phase I Small Business Innovative Research (SBIR) award from the Army Research Office to develop, design, and construct a small non-thermal plasma reactor for laboratory studies ("Non-Thermal Plasma Reactor for Control of Fugitive Emissions of Toxic Gases")

  12. Ecotoxicological studies of environmental samples from Buenos Aires area using a standardized amphibian embryo toxicity test (AMPHITOX).

    PubMed

    Herkovits, Jorge; Perez-Coll, Cristina; Herkovits, Francisco D

    2002-01-01

    The toxicity of 34 environmental samples from potentially polluted and reference stations were evaluated by means of the AMPHITOX test from acute to chronic exposure according to the toxicity found in each sample. The samples were obtained from surface and ground water, leaches, industrial effluents and soils. The data, expressed in acute, short-term chronic and chronic Toxicity Units (TUa, TUstc and TUc) resulted in a maximal value of 1000 TUc, found in a leach, while the lower toxicity value was 1.4 TUa corresponding to two surface water samples. In five samples (four providing from reference places) no toxicity was detected. The results point out the possibility of evaluating the toxicity of a wide diversity of samples by means of AMPHITOX as a customized toxicity test. The fact that almost all samples with suspected toxicity in rivers and streams from the Metropolitan area of Buenos Aires city resulted toxic, indicates the need of enhanced stewardship of chemical substances for environmental and human health protection purposes. PMID:11808551

  13. Organic toxicants in air and precipitation samples from the Lake Michigan area

    SciTech Connect

    Harlin, K.S.; Sweet, C.W.; Gatz, D.F.

    1995-12-31

    Measurements of PCBs, organochlorine insecticides, PAHs, and atrazine were made in air and precipitation samples collected at regionally-representative locations near Lake Michigan from 1992-1995. The purpose of these measurements was to provide information needed to estimate the atmospheric deposition of organic toxicants to Lake Michigan. Twenty-four hour samples of airborne particles and vapor were collected at 12-day intervals on quartz fiber filters and XAD-2 resin vapor traps using modified high volume sampleers. Twenty-eight day precipitation samples were collected using wet-only samplers with stainless steel sampling surfaces and heated enclosure containing an XAD-2 resin adsorption column. Samples were Soxhlet extracted for 24 hours with hexane:acetone (1:1), and concentrated by rotary evaporation. Interferences were removed and the samples separated into analyte groups by silica gel chromatography. Four fractions were collected for GC-ECD and GC-Ion Trap MS analyses. Ten pesticides, 101 PCB congeners, 18 PAHs, and atrazine were measured in all samples. Quality assurance was maintained by including field duplicate samples, field blanks, alboratory matrix spikes, laboratory matrix blanks, and laboratory surrogate spikes in the sampling/analytical protocols. Preliminary results from urban and remote sites show geographical variations in the concentrations of some toxicants due to contributions from local sources. For all sites the total PCB levels are higher in the vapor phase than the particulate phase and show strong seasonal variations. Seasonal variations were also observed for several pesticides.

  14. Validation of an in vitro exposure system for toxicity assessment of air-delivered nanomaterials

    PubMed Central

    Kim, Jong Sung; Peters, Thomas M.; O’Shaughnessy, Patrick T.; Adamcakova-Dodd, Andrea; Thorne, Peter S.

    2013-01-01

    To overcome the limitations of in vitro exposure of submerged lung cells to nanoparticles (NPs), we validated an integrated low flow system capable of generating and depositing airborne NPs directly onto cells at an air–liquid interface (ALI). The in vitro exposure system was shown to provide uniform and controlled dosing of particles with 70.3% efficiency to epithelial cells grown on transwells. This system delivered a continuous airborne exposure of NPs to lung cells without loss of cell viability in repeated 4 h exposure periods. We sequentially exposed cells to air-delivered copper (Cu) NPs in vitro to compare toxicity results to our prior in vivo inhalation studies. The evaluation of cellular dosimetry indicated that a large amount of Cu was taken up, dissolved and released into the basolateral medium (62% of total mass). Exposure to Cu NPs decreased cell viability to 73% (p < 0.01) and significantly (p < 0.05) elevated levels of lactate dehydrogenase, intracellular reactive oxygen species and interleukin-8 that mirrored our findings from subacute in vivo inhalation studies in mice. Our results show that this exposure system is useful for screening of NP toxicity in a manner that represents cellular responses of the pulmonary epithelium in vivo. PMID:22981796

  15. The cold air drainage model KLAM_21

    NASA Astrophysics Data System (ADS)

    Kossmann, M.

    2010-09-01

    A brief description of the physics and numerical techniques of the cold air drainage model KLAM_21 is presented. The model has been developed by the Deutscher Wetterdienst (Sievers, 2005) for simulations of nocturnal airflow in hilly and mountainous terrain under dry fair weather conditions. The model has been widely used as an environmental consultancy tool. Typical model applications include frost protection (cold air ponding) and air quality (nocturnal ventilation). The single-layer model calculates the depth and the mean wind of a surface based stable layer that evolves from a neutrally stratified atmosphere during nighttime. The prediction of the velocity and direction of the cold air drainage is based on vertically averaged momentum tendency equations. Temporal changes in the total heat deficit in the cold air layer are calculated from a prescribed local heat loss rate (describing turbulent and radiative cooling) and advection (donor-cell algorithm). The depth of the cold air layer (depth of the surface based temperature inversion) is calculated diagnostically from the total heat loss deficit. The model is initialised with neutral stratification at sunset (onset time of nocturnal cooling). Optionally, effects of an ambient (regional) wind and/or the dispersion of a passive tracer can be simulated. Integration over time is carried out on a regular Arakawa C grid using dynamically calculated time steps. Spatial gradients are discretised using centred differential quotients. The standard size of the computational domains can reach up to 1500 x 1500 grid cells. Grid resolutions usually range between 10 m and 500 m. High resolution simulation can be limited to a nested inner grid domain, while the courser outer domain is covering the entire airshed of interest. A friendly user interface allows easy setup, control, and evaluation of model simulations. Some selected examples of KLAM_21 applications are shown to illustrate the features and capabilities of the model

  16. Pyrolysis of polymeric materials. I - Effect of chemical structure, temperature, heating rate, and air flow on char yield and toxicity

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Casey, C. J.

    1979-01-01

    Various polymeric materials, including synthetic polymers and cellulosic materials, were evaluated at different temperatures, heating rates and air flow rates for thermophysical and toxicological responses. It is shown that char yields appeared to be a function of air access as much as of the chemical structure of the material. It is stated that the sensitivity of the apparent thermal stability of some materials to air access is so marked that thermogravimetric studies in oxygen-free atmospheres may be a consistently misleading approach to comparing synthetic polymers intended to increase fire safety. Toxicity also appeared to be a function of temperature and air access as much as of the chemical structure of the material. Toxicity of the gases evolved seemed to increase with increasing char yield for some polymers.

  17. Air freight demand models: An overview

    NASA Technical Reports Server (NTRS)

    Dajani, J. S.; Bernstein, G. W.

    1978-01-01

    A survey is presented of some of the approaches which have been considered in freight demand estimation. The few existing continuous time computer simulations of aviation systems are reviewed, with a view toward the assessment of this approach as a tool for structuring air freight studies and for relating the different components of the air freight system. The variety of available data types and sources, without which the calibration, validation and the testing of both modal split and simulation models would be impossible are also reviewed.

  18. Modelling interactions of toxicants and density dependence in wildlife populations

    USGS Publications Warehouse

    Schipper, Aafke M.; Hendriks, Harrie W.M.; Kauffman, Matthew J.; Hendriks, A. Jan; Huijbregts, Mark A.J.

    2013-01-01

    1. A major challenge in the conservation of threatened and endangered species is to predict population decline and design appropriate recovery measures. However, anthropogenic impacts on wildlife populations are notoriously difficult to predict due to potentially nonlinear responses and interactions with natural ecological processes like density dependence. 2. Here, we incorporated both density dependence and anthropogenic stressors in a stage-based matrix population model and parameterized it for a density-dependent population of peregrine falcons Falco peregrinus exposed to two anthropogenic toxicants [dichlorodiphenyldichloroethylene (DDE) and polybrominated diphenyl ethers (PBDEs)]. Log-logistic exposure–response relationships were used to translate toxicant concentrations in peregrine falcon eggs to effects on fecundity. Density dependence was modelled as the probability of a nonbreeding bird acquiring a breeding territory as a function of the current number of breeders. 3. The equilibrium size of the population, as represented by the number of breeders, responded nonlinearly to increasing toxicant concentrations, showing a gradual decrease followed by a relatively steep decline. Initially, toxicant-induced reductions in population size were mitigated by an alleviation of the density limitation, that is, an increasing probability of territory acquisition. Once population density was no longer limiting, the toxicant impacts were no longer buffered by an increasing proportion of nonbreeders shifting to the breeding stage, resulting in a strong decrease in the equilibrium number of breeders. 4. Median critical exposure concentrations, that is, median toxicant concentrations in eggs corresponding with an equilibrium population size of zero, were 33 and 46 μg g−1 fresh weight for DDE and PBDEs, respectively. 5. Synthesis and applications. Our modelling results showed that particular life stages of a density-limited population may be relatively insensitive to

  19. AIR QUALITY MODELING OF AMMONIA: A REGIONAL MODELING PERSPECTIVE

    EPA Science Inventory

    The talk will address the status of modeling of ammonia from a regional modeling perspective, yet the observations and comments should have general applicability. The air quality modeling system components that are central to modeling ammonia will be noted and a perspective on ...

  20. Combinatorial QSAR modeling of chemical toxicants tested against Tetrahymena pyriformis.

    PubMed

    Zhu, Hao; Tropsha, Alexander; Fourches, Denis; Varnek, Alexandre; Papa, Ester; Gramatica, Paola; Oberg, Tomas; Dao, Phuong; Cherkasov, Artem; Tetko, Igor V

    2008-04-01

    Selecting most rigorous quantitative structure-activity relationship (QSAR) approaches is of great importance in the development of robust and predictive models of chemical toxicity. To address this issue in a systematic way, we have formed an international virtual collaboratory consisting of six independent groups with shared interests in computational chemical toxicology. We have compiled an aqueous toxicity data set containing 983 unique compounds tested in the same laboratory over a decade against Tetrahymena pyriformis. A modeling set including 644 compounds was selected randomly from the original set and distributed to all groups that used their own QSAR tools for model development. The remaining 339 compounds in the original set (external set I) as well as 110 additional compounds (external set II) published recently by the same laboratory (after this computational study was already in progress) were used as two independent validation sets to assess the external predictive power of individual models. In total, our virtual collaboratory has developed 15 different types of QSAR models of aquatic toxicity for the training set. The internal prediction accuracy for the modeling set ranged from 0.76 to 0.93 as measured by the leave-one-out cross-validation correlation coefficient ( Q abs2). The prediction accuracy for the external validation sets I and II ranged from 0.71 to 0.85 (linear regression coefficient R absI2) and from 0.38 to 0.83 (linear regression coefficient R absII2), respectively. The use of an applicability domain threshold implemented in most models generally improved the external prediction accuracy but at the same time led to a decrease in chemical space coverage. Finally, several consensus models were developed by averaging the predicted aquatic toxicity for every compound using all 15 models, with or without taking into account their respective applicability domains. We find that consensus models afford higher prediction accuracy for the

  1. DIESEL TRUCK IDLING EMISSIONS - MOBILE SOURCE AIR TOXICS MEASURED AT A HOT SPOT

    SciTech Connect

    Parks, II, James E; Storey, John Morse; Miller, Terry L.; Fu, Joshua S.; Hromis, Boris

    2007-01-01

    Mobile Source Air Toxics (MSATs) are of growing concern due to recent studies linking health risk to residency near heavily traveled roadways. Few research studies on MSAT emissions have been performed due to several factors; those factors include: the difficulty of measuring MSATs due to their semi-volatile nature, lower relative concentration in comparison to NOx and other criteria emissions, and fewer regulations on MSATs. In this paper, measurements of MSATs at a "hot spot" of poor air quality created by a high population of idling heavy-duty trucks are presented. The study area was the Watt Road-Interstate-40/75 interchange just west of Knoxville, TN where approximately 20,000 heavy-duty trucks travel along the interstate each day and hundreds of heavy-duty trucks idle at three large truck stops near the interchange. The air quality in the local area surrounding the interchange is affected negatively by the high number of mobile sources as well as geographic and meteorological conditions; the interchange lies in a valley between two ridges which slows long range transport of pollutants especially in winter months when temperature inversion occurs frequently. Ambient air quality was measured during summer and winter months of two separate years at three sites: a site in one of the truckstops, a site near the interstate roadway, and a site on top of one of the surrounding ridges chosen as a background site for comparison. Results of criteria pollutants measured at these sites are reported in a companion paper by Miller et. al.; the results presented here include measurements of MSATs such as formaldehyde, acetaldehyde, acrolein, and other species obtained via collection on di-nitrophenyl hydrazine (DNPH) filters. Also, preliminary measurements of poly-aromatic hydrocarbons are presented. The results indicate that emissions from idling heavy-duty trucks are a primary contributor of MSATs to local air quality near areas of high static truck traffic; furthermore

  2. DESCRIPTION OF ATMOSPHERIC TRANSPORT PROCESSES IN EULERIAN AIR QUALITY MODELS

    EPA Science Inventory

    Key differences among many types of air quality models are the way atmospheric advection and turbulent diffusion processes are treated. Gaussian models use analytical solutions of the advection-diffusion equations. Lagrangian models use a hypothetical air parcel concept effecti...

  3. Geographic boundaries in breast, lung and colorectal cancers in relation to exposure to air toxics in Long Island, New York

    PubMed Central

    Jacquez, Geoffrey M; Greiling, Dunrie A

    2003-01-01

    Background This two-part study employs several statistical techniques to evaluate the geographic distribution of breast cancer in females and colorectal and lung cancers in males and females in Nassau, Queens, and Suffolk counties, New York, USA. In this second paper, we compare patterns in standardized morbidity ratios (SMR values), calculated from New York State Department of Health (NYSDOH) data, to geographic patterns in overall predicted risk (OPR) from air toxics using exposures estimated in the USEPA National Air Toxics Assessment database. Results We identified significant geographic boundaries in SMR and OPR. We found little or no association between the SMR of colorectal and breast cancers and the OPR for each cancer from exposure to the air toxics. We did find boundaries in male and female lung cancer SMR and boundaries in lung cancer OPR to be closer to one another than expected. Conclusion While consistent with a causal relationship between air toxics and lung cancer incidence, the boundary analysis does not demonstrate the existence of a causal relationship. However, now that the areas of overlap between boundaries in lung cancer incidence and potential airborne exposures have been identified, we can begin to evaluate local- as well as large-scale determinants of lung cancer. PMID:12633502

  4. PREVENTION REFERENCE MANUAL: CONTROL TECHNOLOGIES, VOL. 2. POST-RELEASE MITIGATION MEASURES FOR CONTROLLING ACCIDENTAL RELEASES OF AIR TOXICS

    EPA Science Inventory

    The volume discusses prevention and protection measures for controlling accidental releases of air toxics. The probability of accidental releases depends on the extent to which deviations (in magnitude and duration) in the process can be tolerated before a loss of chemical contai...

  5. CHANGES IN HEART RATE VARIABILITY AND LUNG FUNCTION OBSERVED IN NC PATROL TROOPERS EXPOSED TO PM AND AIR TOXICS

    EPA Science Inventory

    Changes in Heart Rate Variability and Lung Function in NC Patrol Troopers exposed to PM and Air Toxics

    Michael Riediker1, Wayne E Cascio1, Robert B Devlin2, Thomas Griggs1&4, Margaret Herbst1, Ronald W Williams3, Steve P McCorquodale4, Philip A Bromberg1
    1) University o...

  6. SPATIAL AND TEMPORAL VARIABILITY OF MOBILE SOURCE AIR TOXICS IN THE DETROIT EXPOSURE AND AEROSOL RESEARCH STUDY

    EPA Science Inventory

    Data from the first two years of the Detroit Exposure and Aerosol Research Study (DEARS) were evaluated to determine spatial and temporal characteristics in concentrations of mobile source air toxics (MSATs). Outdoor concentrations of MSATs were significantly higher in samples co...

  7. Relationship of Racial Composition and Cancer Risks from Air Toxics Exposure in Memphis, Tennessee, U.S.A.

    PubMed Central

    Jia, Chunrong; James, Wesley; Kedia, Satish

    2014-01-01

    African Americans in the U.S. often live in poverty and segregated urban neighborhoods, many of which have dense industrial facilities resulting in high exposure to harmful air toxics. This study aims to explore the relationship between racial composition and cancer risks from air toxics exposure in Memphis/Shelby County, Tennessee, U.S.A. Air toxics data were obtained from 2005 National Air Toxics Assessment (NATA), and the demographic data, including racial composition, were extracted from the 2000 United States Census. The association was examined using multivariable geographically weighted regression (GWR) analysis. The risk difference between African American and White concentrated areas was defined as the absolute disparity, and the percent difference as the relative disparity. GWR analyses show that cancer risks increase with respect to increasing percent of African Americans at the census tract level. Individuals in African American concentrated tracts bear 6% more cancer risk burden than in White concentrated tracts. The distribution of major roads causes the largest absolute disparity and the distribution of industrial facilities causes the largest relative disparity. Effective strategies for reduction in environmental disparity should especially target sources of large absolute disparities. PMID:25089776

  8. Interspecies quantitative structure-toxicity-toxicity (QSTTR) relationship modeling of ionic liquids. Toxicity of ionic liquids to V. fischeri, D. magna and S. vacuolatus.

    PubMed

    Das, Rudra Narayan; Roy, Kunal; Popelier, Paul L A

    2015-12-01

    Considering the increasing uses of ionic liquids (ILs) in various industrial processes and chemical engineering operations, a complete assessment of their hazardous profile is essential. In the absence of adequate experimental data, in silico modeling might be helpful in filling data gaps for the toxicity of ILs towards various ecological indicator organisms. Using the rationale of taxonomic relatedness, the development of predictive quantitative structure-toxicity-toxicity relationship (QSTTR) models allows predicting the toxicity of ILs to a particular species using available experimental toxicity data towards a different species. Such studies may employ, along with the available experimental toxicity data to a species, molecular structure features and physicochemical properties of chemicals as independent variables for prediction of the toxicity profile against another closely related species. A few such interspecies toxicity correlation models have been reported in the literature for diverse chemicals in general, but this approach has been rarely applied to the class of ionic liquids. The present study involves the use of IL toxicity data towards the bacteria Vibrio fischeri along with molecular structure derived information or computational descriptors like extended topochemical atom (ETA) indices, quantum topological molecular similarity (QTMS) descriptors and computed lipophilicity measure (logk0) for the interspecies exploration of the toxicity data towards green algae S. vacuolatus and crustacea Daphnia magna, separately. This modeling study has been performed in accordance with the OECD guidelines. Finally, predictions for a true external set have been performed to fill the data gap of toxicity towards daphnids and algae using the Vibrio toxicity data and molecular structure attributes. PMID:26414597

  9. Interspecies quantitative structure-toxicity-toxicity (QSTTR) relationship modeling of ionic liquids. Toxicity of ionic liquids to V. fischeri, D. magna and S. vacuolatus.

    PubMed

    Das, Rudra Narayan; Roy, Kunal; Popelier, Paul L A

    2015-12-01

    Considering the increasing uses of ionic liquids (ILs) in various industrial processes and chemical engineering operations, a complete assessment of their hazardous profile is essential. In the absence of adequate experimental data, in silico modeling might be helpful in filling data gaps for the toxicity of ILs towards various ecological indicator organisms. Using the rationale of taxonomic relatedness, the development of predictive quantitative structure-toxicity-toxicity relationship (QSTTR) models allows predicting the toxicity of ILs to a particular species using available experimental toxicity data towards a different species. Such studies may employ, along with the available experimental toxicity data to a species, molecular structure features and physicochemical properties of chemicals as independent variables for prediction of the toxicity profile against another closely related species. A few such interspecies toxicity correlation models have been reported in the literature for diverse chemicals in general, but this approach has been rarely applied to the class of ionic liquids. The present study involves the use of IL toxicity data towards the bacteria Vibrio fischeri along with molecular structure derived information or computational descriptors like extended topochemical atom (ETA) indices, quantum topological molecular similarity (QTMS) descriptors and computed lipophilicity measure (logk0) for the interspecies exploration of the toxicity data towards green algae S. vacuolatus and crustacea Daphnia magna, separately. This modeling study has been performed in accordance with the OECD guidelines. Finally, predictions for a true external set have been performed to fill the data gap of toxicity towards daphnids and algae using the Vibrio toxicity data and molecular structure attributes.

  10. Characterization of a developmental toxicity dose-response model

    SciTech Connect

    Faustman, E.M.; Wellington, D.G.; Smith, W.P.; Kimmel, C.A.

    1989-02-01

    The Rai and Van Ryzin dose-response model proposed for teratology experiments has been characterized for its appropriateness and applicability in modeling the dichotomous response data from developmental toxicity studies. Modifications were made in the initial probability statements to reflect more accurately biological events underlying developmental toxicity. Data sets used for the evaluation were obtained from the National Toxicology Program and U.S. EPA laboratories. The studies included developmental evaluations of ethylene glycol, diethylhexyl phthalate, di- and triethylene glycol dimethyl ethers, and nitrofen in rats, mice, or rabbits. Graphic examination and statistical evaluation demonstrate that this model is sensitive to the data when compared to directly measured experimental outcomes. The model was used to interpolate to low-risk dose levels, and comparisons were made between the values obtained and the no-observed-adverse-effect levels (NOAELs) divided by an uncertainty factor. Our investigation suggests that the Rai and Van Ryzin model is sensitive to the developmental toxicity end points, prenatal deaths, and malformations, and appears to model closely their relationship to dose.

  11. AIR INGRESS ANALYSIS: COMPUTATIONAL FLUID DYNAMIC MODELS

    SciTech Connect

    Chang H. Oh; Eung S. Kim; Richard Schultz; Hans Gougar; David Petti; Hyung S. Kang

    2010-08-01

    The Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy, is performing research and development that focuses on key phenomena important during potential scenarios that may occur in very high temperature reactors (VHTRs). Phenomena Identification and Ranking Studies to date have ranked an air ingress event, following on the heels of a VHTR depressurization, as important with regard to core safety. Consequently, the development of advanced air ingress-related models and verification and validation data are a very high priority. Following a loss of coolant and system depressurization incident, air will enter the core of the High Temperature Gas Cooled Reactor through the break, possibly causing oxidation of the in-the core and reflector graphite structure. Simple core and plant models indicate that, under certain circumstances, the oxidation may proceed at an elevated rate with additional heat generated from the oxidation reaction itself. Under postulated conditions of fluid flow and temperature, excessive degradation of the lower plenum graphite can lead to a loss of structural support. Excessive oxidation of core graphite can also lead to the release of fission products into the confinement, which could be detrimental to a reactor safety. Computational fluid dynamic model developed in this study will improve our understanding of this phenomenon. This paper presents two-dimensional and three-dimensional CFD results for the quantitative assessment of the air ingress phenomena. A portion of results of the density-driven stratified flow in the inlet pipe will be compared with results of the experimental results.

  12. Web-Based Toxic Gas Dispersion Model for Shuttle Launch Operations

    NASA Technical Reports Server (NTRS)

    Bardina, Jorge; Thirumalainambi, Rajkumar

    2004-01-01

    During the launch of the Space Shuttle vehicle, the burning of liquid hydrogen fuel with liquid oxygen at extreme high temperatures inside the three space shuttle main engines, and the burning of the solid propellant mixture of ammonium perchlorate oxidizer, aluminum fuel, iron oxide catalyst, polymer binder, and epoxy curing agent in the two solid rocket boosters result in the formation of a large cloud of hot, buoyant toxic exhaust gases near the ground level which subsequently rises and entrains into ambient air until the temperature and density of the cloud reaches an approximate equilibrium with ambient conditions. In this paper, toxic gas dispersion for various gases are simulated over the web for varying environmental conditions which is provided by rawinsonde data. The model simulates chemical concentration at ground level up to 10 miles (1 KM grids) in downrange up to an hour after launch. The ambient concentration of the gas dispersion and the deposition of toxic particles are used as inputs for a human health risk assessment model. The advantage of the present model is the accessibility and dissemination of model results to other NASA centers over the web. The model can be remotely operated and various scenarios can be analyzed.

  13. Production of toxic shock syndrome toxin 1 by Staphylococcus aureus restricted to endogenous air in tampons.

    PubMed

    Reiser, R F; Hinzman, S J; Bergdoll, M S

    1987-08-01

    All types of four brands of tampons were tested in triplicate by a tampon sac method for their effect on production of toxic shock syndrome toxin 1 (TSST-1). In this method the available air is limited to that which is in the tampon sac. Tampons were weighed and inserted into dialysis sacs inoculated with a TSST-1-producing Staphylococcus aureus strain; the sacs were submerged into brain heart infusion agar, which was allowed to harden around the sacs, and were incubated for 18 h at 37 degrees C. The tampons were removed, weighed, and extracted; the CFU of staphylococci and the amount of toxin present in the extracts were determined. Glass wool was used in place of the tampons as one control, and inoculated empty sacs were used as a second control. The total CFU were consistently greater than 2 X 10(11) for the tampons and glass wool and less than or equal to 10(11) for the empty sac control. Total toxin production for all tampons tested and the glass wool was 2 to 10 times higher than the toxin produced with the empty sac control. These results indicate that tampons provide increased surface area for the staphylococci to grow and adequate oxygen for toxin production. No significant inhibition of growth of the staphylococci or TSST-1 production by any of the tampons tested was noted.

  14. 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. PMID:25694074

  15. 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.

  16. Genetic variance of tolerance and the toxicant threshold model.

    PubMed

    Tanaka, Yoshinari; Mano, Hiroyuki; Tatsuta, Haruki

    2012-04-01

    A statistical genetics method is presented for estimating the genetic variance (heritability) of tolerance to pollutants on the basis of a standard acute toxicity test conducted on several isofemale lines of cladoceran species. To analyze the genetic variance of tolerance in the case when the response is measured as a few discrete states (quantal endpoints), the authors attempted to apply the threshold character model in quantitative genetics to the threshold model separately developed in ecotoxicology. The integrated threshold model (toxicant threshold model) assumes that the response of a particular individual occurs at a threshold toxicant concentration and that the individual tolerance characterized by the individual's threshold value is determined by genetic and environmental factors. As a case study, the heritability of tolerance to p-nonylphenol in the cladoceran species Daphnia galeata was estimated by using the maximum likelihood method and nested analysis of variance (ANOVA). Broad-sense heritability was estimated to be 0.199 ± 0.112 by the maximum likelihood method and 0.184 ± 0.089 by ANOVA; both results implied that the species examined had the potential to acquire tolerance to this substance by evolutionary change.

  17. Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilizaton

    SciTech Connect

    David Hassett; Loreal Heebink; Debra Pflughoeft-Hassett; Tera Buckley; Erick Zacher; Mei Xin; Mae Sexauer Gustin; Rob Jung

    2007-03-31

    The University of North Dakota Energy & Environmental Research Center (EERC) conducted a multiyear study to evaluate the impact of mercury and other air toxic elements (ATEs) on the management of coal combustion by-products (CCBs). The ATEs evaluated in this project were arsenic, cadmium, chromium, lead, nickel, and selenium. The study included laboratory tasks to develop measurement techniques for mercury and ATE releases, sample characterization, and release experiments. A field task was also performed to measure mercury releases at a field site. Samples of fly ash and flue gas desulfurization (FGD) materials were collected preferentially from full-scale coal-fired power plants operating both without and with mercury control technologies in place. In some cases, samples from pilot- and bench-scale emission control tests were included in the laboratory studies. Several sets of 'paired' baseline and test fly ash and FGD materials collected during full-scale mercury emission control tests were also included in laboratory evaluations. Samples from mercury emission control tests all contained activated carbon (AC) and some also incorporated a sorbent-enhancing agent (EA). Laboratory release experiments focused on measuring releases of mercury under conditions designed to simulate CCB exposure to water, ambient-temperature air, elevated temperatures, and microbes in both wet and dry conditions. Results of laboratory evaluations indicated that: (1) Mercury and sometimes selenium are collected with AC used for mercury emission control and, therefore, present at higher concentrations than samples collected without mercury emission controls present. (2) Mercury is stable on CCBs collected from systems both without and with mercury emission controls present under most conditions tested, with the exception of vapor-phase releases of mercury exposed to elevated temperatures. (3) The presence of carbon either from added AC or from unburned coal can result in mercury being

  18. Between-airport heterogeneity in air toxics emissions associated with individual cancer risk thresholds and population risks

    PubMed Central

    2009-01-01

    Background Airports represent a complex source type of increasing importance contributing to air toxics risks. Comprehensive atmospheric dispersion models are beyond the scope of many applications, so it would be valuable to rapidly but accurately characterize the risk-relevant exposure implications of emissions at an airport. Methods In this study, we apply a high resolution atmospheric dispersion model (AERMOD) to 32 airports across the United States, focusing on benzene, 1,3-butadiene, and benzo [a]pyrene. We estimate the emission rates required at these airports to exceed a 10-6 lifetime cancer risk for the maximally exposed individual (emission thresholds) and estimate the total population risk at these emission rates. Results The emission thresholds vary by two orders of magnitude across airports, with variability predicted by proximity of populations to the airport and mixing height (R2 = 0.74–0.75 across pollutants). At these emission thresholds, the population risk within 50 km of the airport varies by two orders of magnitude across airports, driven by substantial heterogeneity in total population exposure per unit emissions that is related to population density and uncorrelated with emission thresholds. Conclusion Our findings indicate that site characteristics can be used to accurately predict maximum individual risk and total population risk at a given level of emissions, but that optimizing on one endpoint will be non-optimal for the other. PMID:19426510

  19. Adaptive modelling of structured molecular representations for toxicity prediction

    NASA Astrophysics Data System (ADS)

    Bertinetto, Carlo; Duce, Celia; Micheli, Alessio; Solaro, Roberto; Tiné, Maria Rosaria

    2012-12-01

    We investigated the possibility of modelling structure-toxicity relationships by direct treatment of the molecular structure (without using descriptors) through an adaptive model able to retain the appropriate structural information. With respect to traditional descriptor-based approaches, this provides a more general and flexible way to tackle prediction problems that is particularly suitable when little or no background knowledge is available. Our method employs a tree-structured molecular representation, which is processed by a recursive neural network (RNN). To explore the realization of RNN modelling in toxicological problems, we employed a data set containing growth impairment concentrations (IGC50) for Tetrahymena pyriformis.

  20. Air Pollution Data for Model Evaluation and Application

    EPA Science Inventory

    One objective of designing an air pollution monitoring network is to obtain data for evaluating air quality models that are used in the air quality management process and scientific discovery.1.2 A common use is to relate emissions to air quality, including assessing ...

  1. A statistical model for characterizing common air pollutants in air-conditioned offices

    NASA Astrophysics Data System (ADS)

    Wong, L. T.; Mui, K. W.; Hui, P. S.

    Maintaining acceptable indoor air quality (IAQ) for a healthy environment is of primary concern, policymakers have developed different strategies to address the performance of it based on proper assessment methodologies and monitoring plans. It could be cost prohibitive to sample all toxic pollutants in a building. In search of a more manageable number of parameters for cost-effective IAQ assessment, this study investigated the probable correlations among the 12 indoor environmental parameters listed in the IAQ certification scheme of the Hong Kong Environment Protection Department (HKEPD) in 422 Hong Kong offices. These 12 parameters consists of nine indoor air pollutants: carbon dioxide (CO 2), carbon monoxide (CO), respirable suspended particulates (RSP), nitrogen dioxide (NO 2), ozone (O 3), formaldehyde (HCHO), total volatile organic compounds (TVOC), radon (Rn), airborne bacteria count (ABC); and three thermal comfort parameters: temperature ( T), relative humidity (RH) and air velocity ( V). The relative importance of the correlations derived, from largest to smallest loadings, was ABC, Rn, CO, RH, RSP, CO 2, TVOC, O 3, T, V, NO 2 and HCHO. Together with the mathematical expressions derived, an alternative sampling protocol for IAQ assessment with the three 'most representative and independent' parameters namely RSP, CO 2 and TVOC measured in an office environment was proposed. The model validity was verified with on site measurements from 43 other offices in Hong Kong. The measured CO 2, RSP and TVOC concentrations were used to predict the probable levels of the other nine parameters and good agreement was found between the predictions and measurements. This simplified protocol provides an easy tool for performing IAQ monitoring in workplaces and will be useful for determining appropriate mitigation measures to finally honor the certification scheme in a cost-effective way.

  2. Intermedia transfer factors for fifteen toxic pollutants released to air basins in California

    SciTech Connect

    McKone, T.E.; Daniels, J.I.; Chiao, F.F.; Hsieh, D.P.H.

    1993-10-01

    This report provides a summary definition of the intermedia-transfer factors (ITFs). Methods are discussed for estimating these parameters in the absence of measured values, and the estimation errors inherent in these estimation methods are considered. A detailed summary is provided of measured and estimated ITF values for fifteen air contaminants. They include: 1,3 butadiene; cadmium; cellosolve; cellosolve acetate; chloroform; di-2-ethylhexylphthalate; 1,4-dioxame; hexachlorobenzene; inorganic arsenic; inorganic lead; nickel; tetrachloroethylene; toluene; toluene-2,4-diisocyanate; and 1,3-xylene. Recommendations are made regarding the expected value and variance in these values for use in exposure models.

  3. Toxicity of food-relevant nanoparticles in intestinal epithelial models

    NASA Astrophysics Data System (ADS)

    McCracken, Christie

    Nanoparticles are increasingly being incorporated into common consumer products, including in foods and food packaging, for their unique properties at the nanoscale. Food-grade silica and titania are used as anti-caking and whitening agents, respectively, and these particle size distributions are composed of approximately one-third nanoparticles. Zinc oxide and silver nanoparticles can be used for their antimicrobial properties. However, little is known about the interactions of nanoparticles in the body upon ingestion. This study was performed to investigate the role of nanoparticle characteristics including surface chemistry, dissolution, and material type on toxicity to the intestinal epithelium. Only mild acute toxicity of zinc oxide nanoparticles was observed after 24-hour treatment of intestinal epithelial C2BBe1 cells based on the results of toxicity assays measuring necrosis, apoptosis, membrane damage, and mitochondrial activity. Silica and titanium dioxide nanoparticles were not observed to be toxic although all nanoparticles were internalized by cells. In vitro digestion of nanoparticles in solutions representing the stomach and intestines prior to treatment of cells did not alter nanoparticle toxicity. Long-term repeated treatment of cells weekly for 24 hours with nanoparticles did not change nanoparticle cytotoxicity or the growth rate of the treated cell populations. Thus, silica, titanium dioxide, and zinc oxide nanoparticles were found to induce little toxicity in intestinal epithelial cells. Fluorescent silica nanoparticles were synthesized as a model for silica used in foods that could be tracked in vitro and in vivo. To maintain an exterior of pure silica, a silica shell was hydrolyzed around a core particle of quantum dots or a fluorescent dye electrostatically associated with a commercial silica particle. The quantum dots used were optimized from a previously reported microwave quantum dot synthesis to a quantum yield of 40%. Characterization

  4. Preliminary studies on model development for rodent toxicity and its interspecies correlation with aquatic toxicities of pharmaceuticals.

    PubMed

    Das, Rudra Narayan; Sanderson, Hans; Mwambo, Andrew E; Roy, Kunal

    2013-03-01

    Environmental toxicity due to pharmaceuticals has been an issue of serious concern for long time. Development of chemometric models with reliable predictive power has been considered as an effective tool for the design of new drug agents with reduced or without ecotoxic potential. Considering a higher degree of similarity in genetic homology towards drug receptor with mammals, we have used a dataset of 194 compounds with reported rodent, fish, daphnia and algae toxicity data for extrapolation of their toxicity towards humans. Allowing for rodents as the most surrogate to human physiology, attempts have also been made to develop interspecies correlation models keeping rodent toxicity as dependent variable so that any drug without reported rodent toxicity can be predicted using fish, daphnia or algae toxicity data which can be consequently extrapolated to human toxicity. The developed models have been subjected to multiple validation strategies. Acceptable results have been obtained in both cases of direct and interspecies extrapolation quantitative structure-activity relationship models. PMID:23238824

  5. Advanced air revitalization system modeling and testing

    NASA Technical Reports Server (NTRS)

    Dall-Baumann, Liese; Jeng, Frank; Christian, Steve; Edeer, Marybeth; Lin, Chin

    1990-01-01

    To support manned lunar and Martian exploration, an extensive evaluation of air revitalization subsystems (ARS) is being conducted. The major operations under study include carbon dioxide removal and reduction; oxygen and nitrogen production, storage, and distribution; humidity and temperature control; and trace contaminant control. A comprehensive analysis program based on a generalized block flow model was developed to facilitate the evaluation of various processes and their interaction. ASPEN PLUS was used in modelling carbon dioxide removal and reduction. Several life support test stands were developed to test new and existing technologies for their potential applicability in space. The goal was to identify processes which use compact, lightweight equipment and maximize the recovery of oxygen and water. The carbon dioxide removal test stands include solid amine/vacuum desorption (SAVD), regenerative silver oxide chemisorption, and electrochemical carbon dioxide concentration (EDC). Membrane-based carbon dioxide removal and humidity control, catalytic reduction of carbon dioxide, and catalytic oxidation of trace contaminants were also investigated.

  6. In Utero and Early-Life Exposure to Ambient Air Toxics and Childhood Brain Tumors: A Population-Based Case–Control Study in California, USA

    PubMed Central

    von Ehrenstein, Ondine S.; Heck, Julia E.; Park, Andrew S.; Cockburn, Myles; Escobedo, Loraine; Ritz, Beate

    2015-01-01

    Background: Little is known about the influence of environmental factors on the etiology of childhood brain tumors. Objectives: We examined risks for brain tumors in children after prenatal and infant exposure to monitored ambient air toxics. Methods: We ascertained all cases of medulloblastoma, central nervous system primitive neuroectodermal tumor (PNET), and astrocytoma before 6 years of age diagnosed in 1990–2007 from the California Cancer Registry and selected controls randomly from birth rolls matched by birth year. Exposures to air toxics during pregnancy/infancy for 43 PNET, 34 medulloblastoma, and 106 astrocytoma cases and 30,569 controls living within 5 mi of a monitor were determined. With factor analysis we assessed the correlational structures of 26 probable carcinogenic toxics, and estimated odds ratios by brain tumor type in logistic regression models. Results: PNETs (≤ 38 cases) were positively associated with interquartile range (IQR) increases in prenatal exposure to acetaldehyde [odds ratio (OR) = 2.30; 95% CI: 1.44, 3.67], 1,3-butadiene (OR = 2.23; 95% CI: 1.28, 3.88), benzene, and toluene; and with IQR increases in exposure during the first year of life to ortho-dichlorobenzene (OR = 3.27; 95% CI: 1.17, 9.14), 1,3-butadiene (OR = 3.15; 95% CI: 1.57, 6.32), and benzene. All exposures except ortho-dichlorobenzene loaded on the same factor. Medulloblastoma (≤ 30 cases) was associated with prenatal exposure to polycyclic aromatic hydrocarbons (PAHs combined: OR = 1.44; 95% CI: 1.15, 1.80). Exposures to lead and some PAHs during the first year of life were positively associated with astrocytoma, but the confidence intervals included the null value (e.g., for lead, OR = 1.40; 95% CI: 0.97, 2.03). Conclusions: Our data suggest that in utero and infancy exposures to air toxics generated by industrial and road traffic sources may increase the risk of PNET and medulloblastoma, with limited support for increased risks for astrocytoma in children up

  7. Exposure Modeling of Residential Air Exchange Rates for NEXUS Participants

    EPA Science Inventory

    Due to cost and participant burden of personal measurements, air pollution health studies often estimate exposures using local ambient air monitors. Since outdoor levels do not necessarily reflect personal exposures, we developed the Exposure Model for Individuals (EMI) to improv...

  8. Prediction Models are Basis for Rational Air Quality Control

    ERIC Educational Resources Information Center

    Daniels, Anders; Bach, Wilfrid

    1973-01-01

    An air quality control scheme employing meteorological diffusion, time averaging and frequency, and cost-benefit models is discussed. The methods outlined provide a constant feedback system for air quality control. Flow charts and maps are included. (BL)

  9. Exposure Modeling of Residential Air Exchange Rates for NEXUS Participants.

    EPA Science Inventory

    Due to cost and participant burden of personal measurements, air pollution health studies often estimate exposures using local ambient air monitors. Since outdoor levels do not necessarily reflect personal exposures, we developed the Exposure Model for Individuals (EMI) to improv...

  10. Transcriptomic responses of European flounder (Platichthys flesus) to model toxicants.

    PubMed

    Williams, Tim D; Diab, Amer; Ortega, Fernando; Sabine, Victoria S; Godfrey, Rita E; Falciani, Francesco; Chipman, J Kevin; George, Stephen G

    2008-11-11

    The temporal transcriptomic responses in liver of Platichthys flesus to model environmental pollutants were studied over a 16-day time span after intraperitoneal injection with cadmium chloride (50 microg/kg in saline), 3-methylcholanthrene (25 mg/kg in olive oil), Aroclor 1254 (50 mg/kg in olive oil), tert-butyl-hydroperoxide (5 mg/kg in saline), Lindane (25mg/kg in olive oil), perfluoro-octanoic acid (100 mg/kg in olive oil) and their vehicles, olive oil (1 ml/kg) or saline (0.9%). Statistical, gene ontology and supervised analysis clearly demonstrated the progression from acute effects, biological responses to and recovery from the treatments. Key biological processes disturbed by the individual treatments were characterised by gene ontology analyses and individual toxicant-responsive genes and pathways were identified by supervised analyses. Responses to the polyaromatic and chlorinated aromatic compounds showed a degree of commonality but were distinguishable and they were clearly segregated from the responses to the pro-oxidants cadmium and the organic hydroperoxide, as well as from the peroxisomal proliferator, perfluoro-octanoic acid. This study demonstrated the utility of the microarray technique in the identification of toxicant-responsive genes and in discrimination between modes of toxicant action. PMID:18804290

  11. Transcriptomic responses of European flounder (Platichthys flesus) to model toxicants.

    PubMed

    Williams, Tim D; Diab, Amer; Ortega, Fernando; Sabine, Victoria S; Godfrey, Rita E; Falciani, Francesco; Chipman, J Kevin; George, Stephen G

    2008-11-11

    The temporal transcriptomic responses in liver of Platichthys flesus to model environmental pollutants were studied over a 16-day time span after intraperitoneal injection with cadmium chloride (50 microg/kg in saline), 3-methylcholanthrene (25 mg/kg in olive oil), Aroclor 1254 (50 mg/kg in olive oil), tert-butyl-hydroperoxide (5 mg/kg in saline), Lindane (25mg/kg in olive oil), perfluoro-octanoic acid (100 mg/kg in olive oil) and their vehicles, olive oil (1 ml/kg) or saline (0.9%). Statistical, gene ontology and supervised analysis clearly demonstrated the progression from acute effects, biological responses to and recovery from the treatments. Key biological processes disturbed by the individual treatments were characterised by gene ontology analyses and individual toxicant-responsive genes and pathways were identified by supervised analyses. Responses to the polyaromatic and chlorinated aromatic compounds showed a degree of commonality but were distinguishable and they were clearly segregated from the responses to the pro-oxidants cadmium and the organic hydroperoxide, as well as from the peroxisomal proliferator, perfluoro-octanoic acid. This study demonstrated the utility of the microarray technique in the identification of toxicant-responsive genes and in discrimination between modes of toxicant action.

  12. AIR QUALITY MODELING FOR THE TWENTY-FIRST CENTURY

    EPA Science Inventory

    This presentation describes recent and evolving advances in the science of numerical air quality simulation modeling. Emphasis is placed on new developments in particulate matter modeling and atmospheric chemistry, diagnostic modeling tools, and integrated modeling systems. New...

  13. Toxicity issues of organic corrosion inhibitors: Applications of QSAR model

    SciTech Connect

    Singh, W.P.; Bockris, J.O`M.

    1996-12-01

    Less toxic corrosion inhibitors can be designed, if one has a reliable method of estimation of toxicity of these compounds before these are actually synthesized. This paper deals with a review of various methods of estimation of aquatic toxicity of organic compounds and highlights the relationship between the structures of these inhibitors and their aquatic toxicity. Such relationships can form the basis for changing the structure of the existing corrosion inhibitors to make these less toxic.

  14. Ultra High Efficiency ESP for Fine Particulate and Air Toxics Control

    SciTech Connect

    Srinivasachar, Srivats; Pease, Benjamin R.; Porle, Kjell; Mauritzson, Christer; Haythornthwaite, Sheila

    1997-07-01

    Nearly ninety percent of U.S. coal-fired utility boilers are equipped with electrostatic precipitators (ESP). Cost effective retrofittable ESP technologies are the only means to accomplish Department of Energy's (DOE) goal of a major reduction in fine particulate and air toxic emissions from coal-fired power plants. Particles in the size range of 0.1 to 5 {micro}m typically escape ESPs. Metals, such as arsenic, cadmium, lead, molybdenum and antimony, concentrate on these particles. This is the main driver for improved fine particulate control. Vapor phase emissions of mercury, selenium and arsenic are also of major concern. Current dry ESPs, which operate at temperatures greater than 280 F, provide little control for vapor phase toxics. The need for inherent improvement to ESPs has to be considered keeping in perspective the current trend towards the use of low sulfur coals. Switching to low sulfur coals is the dominant approach for SO{sub 2} emission reduction in the utility industry. Low sulfur coals generate high resistivity ash, which can cause an undesirable phenomenon called ''back corona.'' Higher particulate emissions occur if there is back corona in the ESP. Results of the pilot-scale testing identified the ''low temperature ESP'' concept to have the biggest impact for the two low sulfur coals investigated. Lowering the flue gas temperature to 220 F provided the maximum impact in terms of decreased emissions. Intermediate operating temperatures (reduction from 340 to 270 F) also gave significant ESP performance improvement. A significant reduction in particulate emissions was also noted when the flue gas humidity was increased (temperature held constant) from the baseline condition for these moderately high resistivity ash coals. Independent control of flue gas humidity and temperature was an important and a notable element in this project. Mercury emissions were also measured as a function of flue gas temperature. Mercury emissions decreased as the flue

  15. Identifying inequitable exposure to toxic air pollution in racialized and low-income neighbourhoods to support pollution prevention.

    PubMed

    Kershaw, Suzanne; Gower, Stephanie; Rinner, Claus; Campbell, Monica

    2013-05-01

    Numerous environmental justice studies have confirmed a relationship between population characteristics such as low-income or minority status and the location of environmental health hazards. However, studies of the health risks from exposure to harmful substances often do not consider their toxicological characteristics. We used two different methods, the unit-hazard and the distance-based approach, to evaluate demographic and socio-economic characteristics of the population residing near industrial facilities in the City of Toronto, Canada. In addition to the mass of air emissions obtained from the national pollutant release inventory (NPRI), we also considered their toxicity using toxic equivalency potential (TEP) scores. Results from the unit-hazard approach indicate no significant difference in the proportion of low-income individuals living in host versus non-host census tracts (t(107) = 0.3, P = 0.735). However, using the distance-based approach, the proportion of low-income individuals was significantly higher (+5.1%, t(522) = 6.0, P <0.001) in host tracts, while the indicator for "racialized" communities ("visible minority") was 16.1% greater (t(521) = 7.2, P <0.001) within 2 km of a NPRI facility. When the most toxic facilities by non-carcinogenic TEP score were selected, the rate of visible minorities living near the most toxic NPRI facilities was significantly higher (+12.9%, t(352) = 3.5, P = 0.001) than near all other NPRI facilities. TEP scores were also used to identify areas in Toronto that face a double burden of poverty and air toxics exposure in order to prioritise pollution prevention.

  16. Critique of the equivalent air altitude model.

    PubMed

    Conkin, Johnny; Wessel, James H

    2008-10-01

    The adverse effects of hypoxic hypoxia include acute mountain sickness (AMS), high altitude pulmonary edema, and high altitude cerebral edema. It has long been assumed that those manifestations are directly related to reduction in the inspired partial pressure of oxygen (P(I)O2). This assumption underlies the equivalent air altitude (EAA) model, which holds that combinations of barometric pressure (P(B)) and inspired fraction of O2 (F(I)O2) that produce the same P(I)O2 will result in identical physiological responses. However, a growing body of evidence seems to indicate that different combinations of P(B) and P(I)O2 may produce different responses to the same P(I)O2. To investigate this question with respect to AMS, we conducted a search of the literature using the terms hypobaric hypoxia, normobaric hypoxia, and hypobaric normoxia. The results suggest that the EAA model provides only an approximate description of isohypoxia, and that P(B) has an independent effect on hypoxia and AMS. A historical report from 1956 and 15 reports from 1983 to 2005 compare the same hypoxic P(I)O2 at different P(B) with respect to the development of hypoxia and AMS. These data provide evidence for an independent effect of P(B) on hypoxia and AMS, and thereby invalidate EAA as an ideal model of isohypoxia. Refinement of the EAA model is needed, in particular for applications to high altitude where supplemental O2 is inadequate to prevent hypoxic hypoxia. Adjustment through probabilistic statistical modeling to match the current limited experimental observations is one approach to a better isohypoxic model. PMID:18856188

  17. MOAtox: A Comprehensive Mode of Action and Acute Aquatic Toxicity Database for Predictive Model Development

    EPA Science Inventory

    tThe mode of toxic action (MOA) has been recognized as a key determinant of chemical toxicity andas an alternative to chemical class-based predictive toxicity modeling. However, the development ofquantitative structure activity relationship (QSAR) and other models has been limite...

  18. Identifying developmental vascular disruptor compounds using a predictive signature and alternative toxicity models

    EPA Science Inventory

    Identifying Developmental Vascular Disruptor Compounds Using a Predictive Signature and Alternative Toxicity Models Presenting Author: Tamara Tal Affiliation: U.S. EPA/ORD/ISTD, RTP, NC, USA Chemically induced vascular toxicity during embryonic development can result in a wide...

  19. Thermal Stress and Toxicity

    EPA Science Inventory

    Elevating ambient temperature above thermoneutrality exacerbates toxicity of most air pollutants, insecticides, and other toxic chemicals. On the other hand, safety and toxicity testing of toxicants and drugs is usually performed in mice and rats maintained at subthermoneutral te...

  20. Modeling of an air-backed diaphragm in dynamic pressure sensors: Effects of the air cavity

    NASA Astrophysics Data System (ADS)

    Liu, Haijun; Olson, Douglas A.; Yu, Miao

    2014-12-01

    As the key structure of most dynamic pressure sensors, a diaphragm backed by an air cavity plays a critical role in the determination of sensor performance metrics. In this paper, we investigate the influence of air cavity length on the sensitivity and bandwidth. A continuum mechanics model neglecting the air viscous effect is first developed to capture the structural-acoustic coupling between a clamped circular diaphragm and a cylindrical backing air cavity. To facilitate sensor design, close-form approximations are obtained to calculate the static sensitivity and the fundamental natural frequency of the air-backed diaphragm. Parametric studies based on this analytical model show that the air cavity can change both the effective mass and the effective stiffness of the diaphragm. One new finding is that the natural frequency of the air-backed diaphragm behaves differently in three different cavity length ranges. In particular, due to the mass effect of the air cavity being dominant, it is shown for the first time that the natural frequency decreases when the cavity length decreases below a critical value in the short cavity range. Furthermore, a finite element method (FEM) model is developed to validate the continuum mechanics model and to study the damping effect of the air cavity. These results provide important design guidelines for dynamic pressure sensors with air-backed diaphragms.

  1. Evaluating NOx emission inventories for regulatory air quality modeling using satellite and air quality model data

    NASA Astrophysics Data System (ADS)

    Kemball-Cook, Susan; Yarwood, Greg; Johnson, Jeremiah; Dornblaser, Bright; Estes, Mark

    2015-09-01

    The purpose of this study was to assess the accuracy of NOx emissions in the Texas Commission on Environmental Quality's (TCEQ) State Implementation Plan (SIP) modeling inventories of the southeastern U.S. We used retrieved satellite tropospheric NO2 columns from the Ozone Monitoring Instrument (OMI) together with NO2 columns from the Comprehensive Air Quality Model with Extensions (CAMx) to make top-down NOx emissions estimates using the mass balance method. Two different top-down NOx emissions estimates were developed using the KNMI DOMINO v2.0 and NASA SP2 retrievals of OMI NO2 columns. Differences in the top-down NOx emissions estimates made with these two operational products derived from the same OMI radiance data were sufficiently large that they could not be used to constrain the TCEQ NOx emissions in the southeast. The fact that the two available operational NO2 column retrievals give such different top-down NOx emissions results is important because these retrievals are increasingly being used to diagnose air quality problems and to inform efforts to solve them. These results reflect the fact that NO2 column retrievals are a blend of measurements and modeled data and should be used with caution in analyses that will inform policy development. This study illustrates both benefits and challenges of using satellite NO2 data for air quality management applications. Comparison with OMI NO2 columns pointed the way toward improvements in the CAMx simulation of the upper troposphere, but further refinement of both regional air quality models and the NO2 column retrievals is needed before the mass balance and other emission inversion methods can be used to successfully constrain NOx emission inventories used in U.S. regulatory modeling.

  2. A model to predict rate of dissolution of toxic compounds into seawater from an oil spill.

    PubMed

    Riazi, M R; Roomi, Y A

    2008-01-01

    In this paper a semianalytical model has been proposed to predict the rate at which oil components dissolve in water when an oil spill occurs in a marine environment. The model breaks the oil into a number of pseudocomponents proportional to the number of compounds originally present in the oil and calculates the rate of dissolution for each component. In addition, the components are divided into paraffinic, naphthenic, and aromatic hydrocarbon types and the amount of dissolution of each pseudocomponent is calculated versus time. In this method the concentration of most toxic components of oil (mainly monoaromatics) is determined. The model considers variable surface area and slick thickness and requires oil specifications (i.e., American Petroleum Institute [API] gravity and boiling point) in addition to air and water temperatures and speeds. The model has been applied to a Kuwaiti crude oil and its products naphtha and kerosene samples at 20 degrees C and 40 degrees C. The results could be useful in selection of an appropriate method for oil spill clean up as well as simulation of environmental impact of oil spill from toxicity points of view. PMID:19037808

  3. Impact of inherent meteorology uncertainty on air quality model predictions

    EPA Science Inventory

    It is well established that there are a number of different classifications and sources of uncertainties in environmental modeling systems. Air quality models rely on two key inputs, namely, meteorology and emissions. When using air quality models for decision making, it is impor...

  4. Good manufacturing practice for modelling air pollution: Quality criteria for computer models to calculate air pollution

    NASA Astrophysics Data System (ADS)

    Dekker, C. M.; Sliggers, C. J.

    To spur on quality assurance for models that calculate air pollution, quality criteria for such models have been formulated. By satisfying these criteria the developers of these models and producers of the software packages in this field can assure and account for the quality of their products. In this way critics and users of such (computer) models can gain a clear understanding of the quality of the model. Quality criteria have been formulated for the development of mathematical models, for their programming—including user-friendliness, and for the after-sales service, which is part of the distribution of such software packages. The criteria have been introduced into national and international frameworks to obtain standardization.

  5. Occurrence and Concentrations of Toxic VOCs in the Ambient Air of Gumi, an Electronics-Industrial City in Korea.

    PubMed

    Baek, Sung-Ok; Suvarapu, Lakshmi Narayana; Seo, Young-Kyo

    2015-08-05

    This study was carried out to characterize the occurrence and concentrations of a variety of volatile organic compounds (VOCs) including aliphatic, aromatic, halogenated, nitrogenous, and carbonyl compounds, in the ambient air of Gumi City, where a large number of electronics industries are found. Two field monitoring campaigns were conducted for a one year period in 2003/2004 and 2010/2011 at several sampling sites in the city, representing industrial, residential and commercial areas. More than 80 individual compounds were determined in this study, and important compounds were then identified according to their abundance, ubiquity and toxicity. The monitoring data revealed toluene, trichloroethylene and acetaldehyde to be the most significant air toxics in the city, and their major sources were mainly industrial activities. On the other hand, there was no clear evidence of an industrial impact on the concentrations of benzene and formaldehyde in the ambient air of the city. Overall, seasonal variations were not as distinct as locational variations in the VOCs concentrations, whereas the within-day variations showed a typical pattern of urban air pollution, i.e., increase in the morning, decrease in the afternoon, and an increase again in the evening. Considerable decreases in the concentrations of VOCs from 2003 to 2011 were observed. The reductions in the ambient concentrations were confirmed further by the Korean PRTR data in industrial emissions within the city. Significant decreases in the concentrations of benzene and acetaldehyde were also noted, whereas formaldehyde appeared to be almost constant between the both campaigns. The decreased trends in the ambient levels were attributed not only to the stricter regulations for VOCs in Korea, but also to the voluntary agreement of major companies to reduce the use of organic solvents. In addition, a site planning project for an eco-friendly industrial complex is believed to play a contributory role in improving

  6. Occurrence and Concentrations of Toxic VOCs in the Ambient Air of Gumi, an Electronics-Industrial City in Korea

    PubMed Central

    Baek, Sung-Ok; Suvarapu, Lakshmi Narayana; Seo, Young-Kyo

    2015-01-01

    This study was carried out to characterize the occurrence and concentrations of a variety of volatile organic compounds (VOCs) including aliphatic, aromatic, halogenated, nitrogenous, and carbonyl compounds, in the ambient air of Gumi City, where a large number of electronics industries are found. Two field monitoring campaigns were conducted for a one year period in 2003/2004 and 2010/2011 at several sampling sites in the city, representing industrial, residential and commercial areas. More than 80 individual compounds were determined in this study, and important compounds were then identified according to their abundance, ubiquity and toxicity. The monitoring data revealed toluene, trichloroethylene and acetaldehyde to be the most significant air toxics in the city, and their major sources were mainly industrial activities. On the other hand, there was no clear evidence of an industrial impact on the concentrations of benzene and formaldehyde in the ambient air of the city. Overall, seasonal variations were not as distinct as locational variations in the VOCs concentrations, whereas the within-day variations showed a typical pattern of urban air pollution, i.e., increase in the morning, decrease in the afternoon, and an increase again in the evening. Considerable decreases in the concentrations of VOCs from 2003 to 2011 were observed. The reductions in the ambient concentrations were confirmed further by the Korean PRTR data in industrial emissions within the city. Significant decreases in the concentrations of benzene and acetaldehyde were also noted, whereas formaldehyde appeared to be almost constant between the both campaigns. The decreased trends in the ambient levels were attributed not only to the stricter regulations for VOCs in Korea, but also to the voluntary agreement of major companies to reduce the use of organic solvents. In addition, a site planning project for an eco-friendly industrial complex is believed to play a contributory role in improving

  7. Prenatal exposure to air toxics and risk of Wilms’ tumor in 0-5 year old children

    PubMed Central

    Shrestha, Anshu; Ritz, Beate; Wilhelm, Michelle; Qiu, Jiaheng; Cockburn, Myles; Heck, Julia E

    2014-01-01

    Objective To study prenatal air toxics exposure and Wilms’ tumor in children. Methods We identified 337 Wilms’ tumor cases among children <6 years (1988-2008) from the California Cancer Registry, randomly selected 96,514 controls from California birth rolls in 20:1 ratio matched to all cancer cases, then linked birth addresses to air monitors within 15 miles to assess exposures. Multiple logistic regressions were applied to estimate effects. Results Children prenatally exposed to formaldehyde, polycyclic aromatic hydrocarbons, perchloroethylene, or acetaldehyde in the third trimester had an increased odds of Wilms’ tumor per interquartile increase in concentration (OR [95%CI]: 1.28 [1.12, 1.45], 1.10 [0.99, 1.22], 1.09 [1.00, 1.18], 1.25 [1.07, 1.45] respectively). Conclusions We found positive associations for four air toxics. This is the first study of this kind. Future studies are needed to confirm our findings. PMID:24854250

  8. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  9. Personal exposures, indoor-outdoor relationships, and breath levels of toxic air pollutants measured for 355 persons in New Jersey

    NASA Astrophysics Data System (ADS)

    Wallace, Lance A.; Pellizzari, Edo D.; Hartwell, Ty D.; Sparacino, Charles M.; Sheldon, Linda S.; Zelon, Harvey

    EPA's TEAM Study has measured exposures to 20 volatile organic compounds in personal air, outdoor air, drinking water and the breath of 355 persons in NJ, in the fall of 1981. The NJ residents were selected by a probability sampling scheme to represent 128,000 inhabitants of Elizabeth and Bayonne. Participants carried a personal monitor to collect two 12-h air samples and gave a breath sample at the end of the day. Two consecutive 12-h outdoor air samples were also collected on identical Tenax cartridges in the back yards of 90 of the participants. About 3000 samples were collected, of which 1000 were quality control samples. Eleven compounds were often present in air. Personal exposures were consistently higher than outdoor concentrations for these chemicals, and were sometimes ten times the outdoor concentrations. Indoor sources appeared responsible for much of the difference. Breath concentrations also usually exceed outdoor concentrations, and correlated more strongly with personal exposures than with outdoor concentrations. Some activities (smoking, driving, visiting dry cleaners or service stations) and occupations (chemical, paint and plastics plants) were associated with significantly elevated exposures and breath levels for certain toxic chemicals.

  10. A survey of air flow models for multizone structures

    SciTech Connect

    Feustel, H.E.; Dieris, J.

    1991-03-01

    Air flow models are used to simulate the rates of incoming and outgoing air flows for a building with known leakage under given weather and shielding conditions. Additional information about the flow paths and air-mass flows inside the building can only by using multizone air flow models. In order to obtain more information on multizone air flow models, a literature review was performed in 1984. A second literature review and a questionnaire survey performed in 1989, revealed the existence of 50 multizone air flow models, all developed since 1966, two of which are still under development. All these programs use similar flow equations for crack flow but differ in the versatility to describe the full range of flow phenomena and the algorithm provided for solving the set of nonlinear equations. This literature review was found that newer models are able to describe and simulate the ventilation systems and interrelation of mechanical and natural ventilation. 27 refs., 2 figs., 1 tab.

  11. Augmenting aquatic species sensitivity distributions with interspecies toxicity estimation models

    EPA Science Inventory

    Species sensitivity distributions (SSD) are cumulative distribution functions of species toxicity values. The SSD approach is increasingly being used in ecological risk assessment, but is often limited by available toxicity data necessary for diverse species representation. In ...

  12. Dispersion modeling of accidental releases of toxic gases - Comparison of the models and their utility for the fire brigades.

    NASA Astrophysics Data System (ADS)

    Stenzel, S.; Baumann-Stanzer, K.

    2009-04-01

    Dispersion modeling of accidental releases of toxic gases - Comparison of the models and their utility for the fire brigades. Sirma Stenzel, Kathrin Baumann-Stanzer In the case of accidental release of hazardous gases in the atmosphere, the emergency responders need a reliable and fast tool to assess the possible consequences and apply the optimal countermeasures. For hazard prediction and simulation of the hazard zones a number of air dispersion models are available. The most model packages (commercial or free of charge) include a chemical database, an intuitive graphical user interface (GUI) and automated graphical output for display the results, they are easy to use and can operate fast and effective during stress situations. The models are designed especially for analyzing different accidental toxic release scenarios ("worst-case scenarios"), preparing emergency response plans and optimal countermeasures as well as for real-time risk assessment and management. There are also possibilities for model direct coupling to automatic meteorological stations, in order to avoid uncertainties in the model output due to insufficient or incorrect meteorological data. Another key problem in coping with accidental toxic release is the relative width spectrum of regulations and values, like IDLH, ERPG, AEGL, MAK etc. and the different criteria for their application. Since the particulate emergency responders and organizations require for their purposes unequal regulations and values, it is quite difficult to predict the individual hazard areas. There are a quite number of research studies and investigations coping with the problem, anyway the end decision is up to the authorities. The research project RETOMOD (reference scenarios calculations for toxic gas releases - model systems and their utility for the fire brigade) was conducted by the Central Institute for Meteorology and Geodynamics (ZAMG) in cooperation with the Vienna fire brigade, OMV Refining & Marketing GmbH and

  13. Organotypic liver culture models: Meeting current challenges in toxicity testing

    PubMed Central

    LeCluyse, Edward L.; Witek, Rafal P.; Andersen, Melvin E.; Powers, Mark J.

    2012-01-01

    Prediction of chemical-induced hepatotoxicity in humans from in vitro data continues to be a significant challenge for the pharmaceutical and chemical industries. Generally, conventional in vitro hepatic model systems (i.e. 2-D static monocultures of primary or immortalized hepatocytes) are limited by their inability to maintain histotypic and phenotypic characteristics over time in culture, including stable expression of clearance and bioactivation pathways, as well as complex adaptive responses to chemical exposure. These systems are less than ideal for longer-term toxicity evaluations and elucidation of key cellular and molecular events involved in primary and secondary adaptation to chemical exposure, or for identification of important mediators of inflammation, proliferation and apoptosis. Progress in implementing a more effective strategy for in vitro-in vivo extrapolation and human risk assessment depends on significant advances in tissue culture technology and increasing their level of biological complexity. This article describes the current and ongoing need for more relevant, organotypic in vitro surrogate systems of human liver and recent efforts to recreate the multicellular architecture and hemodynamic properties of the liver using novel culture platforms. As these systems become more widely used for chemical and drug toxicity testing, there will be a corresponding need to establish standardized testing conditions, endpoint analyses and acceptance criteria. In the future, a balanced approach between sample throughput and biological relevance should provide better in vitro tools that are complementary with animal testing and assist in conducting more predictive human risk assessment. PMID:22582993

  14. Estimation of Wildlife Hazard Levels Using Interspecies Correlation Models and Standard Laboratory Rodent Toxicity Data

    EPA Science Inventory

    Toxicity data from laboratory rodents are widely available and frequently used in human health assessments as an animal model. We explore the possibility of using single rodent acute toxicity values to predict chemical toxicity to a diversity of wildlife species and to estimate ...

  15. "Air Toxics under the Big Sky": Examining the Effectiveness of Authentic Scientific Research on High School Students' Science Skills and Interest

    ERIC Educational Resources Information Center

    Ward, Tony J.; Delaloye, Naomi; Adams, Earle Raymond; Ware, Desirae; Vanek, Diana; Knuth, Randy; Hester, Carolyn Laurie; Marra, Nancy Noel; Holian, Andrij

    2016-01-01

    "Air Toxics Under the Big Sky" is an environmental science outreach/education program that incorporates the Next Generation Science Standards (NGSS) 8 Practices with the goal of promoting knowledge and understanding of authentic scientific research in high school classrooms through air quality research. This research explored: (1)…

  16. PRELIMINARY FINDINGS ON THE ASSESSMENT OF POTENTIAL CAR-RELATED OCCUPATIONAL PM AND AIR TOXIC EXPOSURE TO PATROL TROOPERS (COPP STUDY)

    EPA Science Inventory

    In-vehicle, roadside and community-based measurements of particulate matter (PM) and select air toxics were measured as part of a study involving patrol cars from the North Carolina Highway Patrol. One goal of this study was to characterize PM and related air pollutant concentra...

  17. Toxic treatments 'in-situ' steam/hot-air stripping technology. Applications analysis report. Rept. for Jun 89-Jun 90

    SciTech Connect

    Jackson, T.

    1991-03-01

    A SITE Demonstration of the Toxic Treatment (USA) Inc. in-situ steam/hot-air stripping technology (Detoxifier) was conducted beginning in the fall of 1989 at the GATX Annex Terminal site located in San Pedro, CA. The chemical storage and transfer facility was contaminated with various solvents due to spillage and a fire. Contamination extended into the salt water table (1.8 meters). Based on the SITE Demonstration and other data, it was concluded that 85% of the volatile organic compounds and 50% of the semivolatile organic compounds were removed from the soil. Fugitive air emissions are very low, and lateral and downward migration of contaminants due to the treatment were minimal. Finally, it was concluded that this in-situ process is cost competitive.

  18. Future research needs associated with the assessment of potential human health risks from exposure to toxic ambient air pollutants.

    PubMed Central

    Möller, L; Schuetzle, D; Autrup, H

    1994-01-01

    This paper presents key conclusions and future research needs from a Workshop on the Risk Assessment of Urban Air, Emissions, Exposure, Risk Identification, and Quantification, which was held in Stockholm during June 1992 by 41 participants from 13 countries. Research is recommended in the areas of identification and quantification of toxics in source emissions and ambient air, atmospheric transport and chemistry, exposure level assessment, the development of improved in vitro bioassays, biomarker development, the development of more accurate epidemiological methodologies, and risk quantification techniques. Studies are described that will be necessary to assess and reduce the level of uncertainties associated with each step of the risk assessment process. International collaborative research efforts between industry and government organizations are recommended as the most effective way to carry out this research. PMID:7529703

  19. VALMET: a valley air pollution model. Final report. Revision 1

    SciTech Connect

    Whiteman, C.D.; Allwine, K.J.

    1985-04-01

    An air quality model is described for predicting air pollution concentrations in deep mountain valleys arising from nocturnal down-valley transport and diffusion of an elevated pollutant plume, and the fumigation of the plume on the valley floor and sidewalls after sunrise. Included is a technical description of the model, a discussion of the model's applications, the required model inputs, sample calculations and model outputs, and a full listing of the FORTRAN computer program. 55 refs., 27 figs., 6 tabs.

  20. Aerosolized ZnO nanoparticles induce toxicity in alveolar type II epithelial cells at the air-liquid interface

    SciTech Connect

    Xie, Yumei; Williams, Nolann G.; Tolic, Ana; Chrisler, William B.; Teeguarden, Justin G.; Maddux, Bettye L.; Pounds, Joel G.; Laskin, Alexander; Orr, Galya

    2012-01-20

    The majority of in vitro studies characterizing the impact of engineered nanoparticles (NPs) on cells that line the respiratory tract were conducted in cells exposed to NPs in suspension. This approach introduces processes that are unlikely to occur during inhaled NP exposures in vivo, such as the shedding of toxic doses of dissolved ions. ZnO NPs are used extensively and pose significant sources for human exposure. Exposures to airborne ZnO NPs can induce adverse effects, but the relevance of the dissolved Zn2+ to the observed effects in vivo is still unclear. Our goal was to mimic in vivo exposures to airborne NPs and decipher the contribution of the intact NP from the contribution of the dissolved ions to airborne ZnO NP toxicity. We established the exposure of alveolar type II epithelial cells to aerosolized NPs at the air-liquid interface (ALI), and compared the impact of aerosolized ZnO NPs and NPs in suspension at the same cellular doses, measured as the number of particles per cell. By evaluating membrane integrity and cell viability 6 and 24 hours post exposure we found that aerosolized NPs induced toxicity at the ALI at doses that were in the same order of magnitude as doses required to induce toxicity in submersed cultures. In addition, distinct patterns of oxidative stress were observed in the two exposure systems. These observations unravel the ability of airborne ZnO NPs to induce toxicity without the contribution of dissolved Zn2+ and suggest distinct mechanisms at the ALI and in submersed cultures.

  1. What is Air? A Standard Model for Combustion Simulations

    SciTech Connect

    Cloutman, L D

    2001-08-01

    Most combustion devices utilize air as the oxidizer. Thus, reactive flow simulations of these devices require the specification of the composition of air as part of the physicochemical input. A mixture of only oxygen and nitrogen often is used, although in reality air is a more complex mixture of somewhat variable composition. We summarize some useful parameters describing a standard model of dry air. Then we consider modifications to include water vapor for creating the desired level of humidity. The ''minor'' constituents of air, especially argon and water vapor, can affect the composition by as much as about 5 percent in the mole fractions.

  2. 77 FR 4808 - Conference on Air Quality Modeling

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-31

    ... AGENCY Conference on Air Quality Modeling AGENCY: U.S. Environmental Protection Agency (EPA). ACTION: Notice of conference. SUMMARY: The EPA will be hosting the Tenth Conference on Air Quality Modeling on...; suggest alternatives and substitute language for your requested changes. Describe any assumptions...

  3. THE ATMOSPHERIC MODEL EVALUATION TOOL (AMET); AIR QUALITY MODULE

    EPA Science Inventory

    This presentation reviews the development of the Atmospheric Model Evaluation Tool (AMET) air quality module. The AMET tool is being developed to aid in the model evaluation. This presentation focuses on the air quality evaluation portion of AMET. Presented are examples of the...

  4. DEVELOPMENT AND ANALYSIS OF AIR QUALITY MODELING SIMULATIONS FOR HAZARDOUS AIR POLLUTANTS

    EPA Science Inventory

    The concentrations of five hazardous air pollutants were simulated using the Community Multi Scale Air Quality (CMAQ) modeling system. Annual simulations were performed over the continental United States for the entire year of 2001 to support human exposure estimates. Results a...

  5. The contrast model method for the thermodynamical calculation of air-air wet heat exchanger

    NASA Astrophysics Data System (ADS)

    Yuan, Xiugan; Mei, Fang

    1989-02-01

    The 'contrast model' method thermodynamic calculation of air-air crossflow wet heat exchangers with initial air condensation is presented. Contrast-model equations are derived from the actual heat exchanger equations as well as imaginary ones; it is then possible to proceed to a proof that the enthalpy efficiency of the contrast model equations is similar to the temperature efficiency of the dry heat exchanger. Conditions are noted under which it becomes possible to unify thermodynamic calculations for wet and dry heat exchangers.

  6. Toxic Acid Gas Absorber Design Considerations for Air Pollution Control in Process Industries

    ERIC Educational Resources Information Center

    Manyele, S. V.

    2008-01-01

    This paper analyses the design parameters for an absorber used for removal of toxic acid gas (in particular sulfur dioxide) from a process gas stream for environmental health protection purposes. Starting from the equilibrium data, Henry's law constant was determined from the slope of the y-x diagram. Based on mass balances across the absorber,…

  7. ENVIRONMENTAL CONTROL OF TOXIC METAL AIR EMISSIONS FROM THE COMBUSTION OF COAL AND WASTES

    EPA Science Inventory

    The paper is concerned with the partitioning of toxic metals (e.g., arsenic, selenium, mercury, chromium, lead, and cadmium) during combustion, and with the mitigation of their effect on the environment using high-temperature sorbents. The paper is divided into three parts: (1) t...

  8. Air toxics and epigenetic effects: ozone altered microRNAs in the sputum of human subjects

    EPA Science Inventory

    Ozone (03) is a criteria air pollutant that is associated with numerous adverse health effects, including altered respiratory immune responses. Despite its deleterious health effects, possible epigenetic mechanisms underlying 03-induced health effects remain understudied. MicroRN...

  9. AIR PARTICULATE POLLUTION CARDIOVASCULAR TOXICITY: HAZARD IDENTIFICATION AND MECHANISMS OF ACTION

    EPA Science Inventory


    The overall weight of evidence from epidemiological studies has shown statistical associations between air particulate pollution exposure and mortality\\morbidity particularly within individuals with cardiovascular disease (1-4). Identification of causal particle properties ...

  10. Bayesian Analysis of a Reduced-Form Air Quality Model

    EPA Science Inventory

    Numerical air quality models are being used for assessing emission control strategies for improving ambient pollution levels across the globe. This paper applies probabilistic modeling to evaluate the effectiveness of emission reduction scenarios aimed at lowering ground-level oz...

  11. INTERCOMPARISON OF ALTERNATIVE VEGETATION DATABASES FOR REGIONAL AIR QUALITY MODELING

    EPA Science Inventory

    Vegetation cover data are used to characterize several regional air quality modeling processes, including the calculation of heat, moisture, and momentum fluxes with the Mesoscale Meteorological Model (MM5) and the estimate of biogenic volatile organic compound and nitric oxide...

  12. Estimation of exposure to toxic releases using spatial interaction modeling

    PubMed Central

    2011-01-01

    Background The United States Environmental Protection Agency's Toxic Release Inventory (TRI) data are frequently used to estimate a community's exposure to pollution. However, this estimation process often uses underdeveloped geographic theory. Spatial interaction modeling provides a more realistic approach to this estimation process. This paper uses four sets of data: lung cancer age-adjusted mortality rates from the years 1990 through 2006 inclusive from the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) database, TRI releases of carcinogens from 1987 to 1996, covariates associated with lung cancer, and the EPA's Risk-Screening Environmental Indicators (RSEI) model. Results The impact of the volume of carcinogenic TRI releases on each county's lung cancer mortality rates was calculated using six spatial interaction functions (containment, buffer, power decay, exponential decay, quadratic decay, and RSEI estimates) and evaluated with four multivariate regression methods (linear, generalized linear, spatial lag, and spatial error). Akaike Information Criterion values and P values of spatial interaction terms were computed. The impacts calculated from the interaction models were also mapped. Buffer and quadratic interaction functions had the lowest AIC values (22298 and 22525 respectively), although the gains from including the spatial interaction terms were diminished with spatial error and spatial lag regression. Conclusions The use of different methods for estimating the spatial risk posed by pollution from TRI sites can give different results about the impact of those sites on health outcomes. The most reliable estimates did not always come from the most complex methods. PMID:21418644

  13. Three dimensional quantitative structure-toxicity relationship modeling and prediction of acute toxicity for organic contaminants to algae.

    PubMed

    Jin, Xiangqin; Jin, Minghao; Sheng, Lianxi

    2014-08-01

    Although numerous chemicals have been identified to have significant toxicological effect on aquatic organisms, there is still lack of a reliable, high-throughput approach to evaluate, screen and monitor the presence of organic contaminants in aquatic system. In the current study, we proposed a synthetic pipeline to automatically model and predict the acute toxicity of chemicals to algae. In the procedure, a new alignment-free three dimensional (3D) structure characterization method was described and, with this method, several 3D-quantitative structure-toxicity relationship (3D-QSTR) models were developed, from which two were found to exhibit strong internal fitting ability and high external predictive power. The best model was established by Gaussian process (GP), which was further employed to perform extrapolation on a random compound library consisting of 1014 virtually generated substituted benzenes. It was found that (i) substitution number can only exert slight influence on chemical׳s toxicity, but low-substituted benzenes seem to have higher toxicity than those of high-substituted entities, and (ii) benzenes substituted by nitro group and halogens exhibit high acute toxicity as compared to other substituents such as methyl and carboxyl groups. Subsequently, several promising candidates suggested by computational prediction were assayed by using a standard algal growth inhibition test. Consequently, four substituted benzenes, namely 2,3-dinitrophenol, 2-chloro-4-nitroaniline, 1,2,3-trinitrobenzene and 3-bromophenol, were determined to have high acute toxicity to Scenedesmus obliquus, with their EC50 values of 2.5±0.8, 10.5±2.1, 1.4±0.2 and 42.7±5.4μmol/L, respectively. PMID:24960624

  14. Intercomparisons of AIRS Observations with MERRA Reanalysis and Climate Models

    NASA Astrophysics Data System (ADS)

    Hearty, T. J.; Vollmer, B.; Theobald, M.; Savtchenko, A. K.; Ding, F.; Esfandiari, A. E.; Ostrenga, D.; Bosilovich, M. G.; Fetzer, E.; Tian, B.; Fishbein, E.; Manning, E.; Yue, Q.

    2012-12-01

    We perform intercomparisons among AIRS (Atmospheric Infrared Sounder) observations, MERRA (Modern-Era Retrospective Analysis for Research and Applications) reanalysis, and CMIP5 models. One of the greatest challenges of using satellite observations from Low Earth Orbit (LEO) to evaluate climate models is to account for differences in the sampling. Climate models are sampled on a regular grid with equal increments in time and space while LEO satellite observations are not. Since AIRS is an infrared instrument its sampling is also affected by clouds. Version 6 of the AIRS processing algorithm will have improved accuracy and increased sampling over the Version 5 algorithm. We compare AIRS and MERRA data with identical sampling to assess how well the satellite observations and reanalysis Water Vapor, Temperature, and Clouds agree when they have the same sampling. Since Version 6 of the AIRS processing algorithms also have improved sampling we use MERRA sampled like AIRS to estimate the improvement in the sampling bias between AIRS Version 5 and Version 6 Results. While the uncertainties in the current generation of climate models are larger than the sampling uncertainties, as the models improve more careful intercomparisons will be necessary. Therefore we compare the differences between AIRS observations and CMIP5 Climate Models to assess the significance of the sampling uncertainties.

  15. Modelling of air pressure effects in casting moulds

    NASA Astrophysics Data System (ADS)

    Attar, E.; Homayonifar, P.; Babaei, R.; Asgari, K.; Davami, P.

    2005-09-01

    In the casting process, as a mould is filled with molten metal, air escapes through the vents. Air pressure in the mould cavity has serious effects upon the filling behaviour such as surface profile of the molten metal and filling time. In this project a computational model was developed for calculation of air pressure during the mould filling. A 3D single phase code based on the SOLA-VOF algorithm was used for the prediction of the fluid flow. The ideal gas assumption, conservation of mass equation and Bernoulli law were used for the calculation of air pressure. A new algorithm was developed to interpolate air pressure on the surface cells. The creation of air pressure was correlated with the sizes of the vents and their locations. An experimental test was designed to verify the modelling results. Comparison between the experimental data and simulation results has shown a good agreement.

  16. Modeling, Monitoring and Fault Diagnosis of Spacecraft Air Contaminants

    NASA Technical Reports Server (NTRS)

    Ramirez, W. Fred; Skliar, Mikhail; Narayan, Anand; Morgenthaler, George W.; Smith, Gerald J.

    1996-01-01

    Progress and results in the development of an integrated air quality modeling, monitoring, fault detection, and isolation system are presented. The focus was on development of distributed models of the air contaminants transport, the study of air quality monitoring techniques based on the model of transport process and on-line contaminant concentration measurements, and sensor placement. Different approaches to the modeling of spacecraft air contamination are discussed, and a three-dimensional distributed parameter air contaminant dispersion model applicable to both laminar and turbulent transport is proposed. A two-dimensional approximation of a full scale transport model is also proposed based on the spatial averaging of the three dimensional model over the least important space coordinate. A computer implementation of the transport model is considered and a detailed development of two- and three-dimensional models illustrated by contaminant transport simulation results is presented. The use of a well established Kalman filtering approach is suggested as a method for generating on-line contaminant concentration estimates based on both real time measurements and the model of contaminant transport process. It is shown that high computational requirements of the traditional Kalman filter can render difficult its real-time implementation for high-dimensional transport model and a novel implicit Kalman filtering algorithm is proposed which is shown to lead to an order of magnitude faster computer implementation in the case of air quality monitoring.

  17. Transgenic mouse models for alcohol metabolism, toxicity, and cancer.

    PubMed

    Heit, Claire; Dong, Hongbin; Chen, Ying; Shah, Yatrik M; Thompson, David C; Vasiliou, Vasilis

    2015-01-01

    Alcohol abuse leads to tissue damage including a variety of cancers; however, the molecular mechanisms by which this damage occurs remain to be fully understood. The primary enzymes involved in ethanol metabolism include alcohol dehydrogenase (ADH), cytochrome P450 isoform 2E1, (CYP2E1), catalase (CAT), and aldehyde dehydrogenases (ALDH). Genetic polymorphisms in human genes encoding these enzymes are associated with increased risks of alcohol-related tissue damage, as well as differences in alcohol consumption and dependence. Oxidative stress resulting from ethanol oxidation is one established pathogenic event in alcohol-induced toxicity. Ethanol metabolism generates free radicals, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS), and has been associated with diminished glutathione (GSH) levels as well as changes in other antioxidant mechanisms. In addition, the formation of protein and DNA adducts associated with the accumulation of ethanol-derived aldehydes can adversely affect critical biological functions and thereby promote cellular and tissue pathology. Animal models have proven to be valuable tools for investigating mechanisms underlying pathogenesis caused by alcohol. In this review, we provide a brief discussion on several animal models with genetic defects in alcohol-metabolizing enzymes and GSH-synthesizing enzymes and their relevance to alcohol research. PMID:25427919

  18. Transgenic Mouse Models for Alcohol Metabolism, Toxicity and Cancer

    PubMed Central

    Heit, Claire; Dong, Hongbin; Chen, Ying; Shah, Yatrik M.; Thompson, David C.; Vasiliou, Vasilis

    2015-01-01

    Alcohol abuse leads to tissue damage including a variety of cancers; however, the molecular mechanisms by which this damage occurs remains to be fully understood. The primary enzymes involved in ethanol metabolism include alcohol dehydrogenase (ADH), cytochrome P450 isoform 2E1, (CYP2E1), catalase (CAT), and aldehyde dehydrogenases (ALDH). Genetic polymorphisms in human genes encoding these enzymes are associated with increased risks of alcohol-related tissue damage, as well as differences in alcohol consumption and dependence. Oxidative stress resulting from ethanol oxidation is one established pathogenic event in alcohol-induced toxicity. Ethanol metabolism generates free radicals, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS), and has been associated with diminished glutathione (GSH) levels as well as changes in other antioxidant mechanisms. In addition, the formation of protein and DNA adducts associated with the accumulation of ethanol-derived aldehydes can adversely affect critical biological functions and thereby promote cellular and tissue pathology. Animal models have proven to be valuable tools for investigating mechanisms underlying pathogenesis caused by alcohol. In this review, we provide a brief discussion on several animal models with genetic defects in alcohol metabolizing enzymes and GSH synthesizing enzymes and their relevance to alcohol research. PMID:25427919

  19. Air toxics exposure from vehicle emissions at a U.S. border crossing: Buffalo Peace Bridge Study.

    PubMed

    Spengler, John; Lwebuga-Mukasa, Jamson; Vallarino, Jose; Melly, Steve; Chillrud, Steve; Baker, Joel; Minegishi, Taeko

    2011-07-01

    The Peace Bridge in Buffalo, New York, which spans the Niagara River at the east end of Lake Erie, is one of the busiest U.S. border crossings. The Peace Bridge plaza on the U.S. side is a complex of roads, customs inspection areas, passport control areas, and duty-free shops. On average 5000 heavy-duty diesel trucks and 20,000 passenger cars traverse the border daily, making the plaza area a potential "hot spot" for emissions from mobile sources. In a series of winter and summer field campaigns, we measured air pollutants, including many compounds considered by the U.S. Environmental Protection Agency (EPA*) as mobile-source air toxics (MSATs), at three fixed sampling sites: on the shore of Lake Erie, approximately 500 m upwind (under predominant wind conditions) of the Peace Bridge plaza; immediately downwind of (adjacent to) the plaza; and 500 m farther downwind, into the community of west Buffalo. Pollutants sampled were particulate matter (PM) < or = 10 microm (PM10) and < or = 2.5 microm (PM2.5) in aerodynamic diameter, elemental carbon (EC), 28 elements, 25 volatile organic compounds (VOCs) including 3 carbonyls, 52 polycyclic aromatic hydrocarbons (PAHs), and 29 nitrogenated polycyclic aromatic hydrocarbons (NPAHs). Spatial patterns of counts of ultrafine particles (UFPs, particles < 0.1 microm in aerodynamic diameter) and of particle-bound PAH (pPAH) concentrations were assessed by mobile monitoring in the neighborhood adjacent to the Peace Bridge plaza using portable instruments and Global Positioning System (GPS) tracking. The study was designed to assess differences in upwind and downwind concentrations of MSATs, in areas near the Peace Bridge plaza on the U.S. side of the border. The Buffalo Peace Bridge Study featured good access to monitoring locations proximate to the plaza and in the community, which are downwind with the dominant winds from the direction of Lake Erie and southern Ontario. Samples from the lakeside Great Lakes Center (GLC), which

  20. Air toxics exposure from vehicle emissions at a U.S. border crossing: Buffalo Peace Bridge Study.

    PubMed

    Spengler, John; Lwebuga-Mukasa, Jamson; Vallarino, Jose; Melly, Steve; Chillrud, Steve; Baker, Joel; Minegishi, Taeko

    2011-07-01

    The Peace Bridge in Buffalo, New York, which spans the Niagara River at the east end of Lake Erie, is one of the busiest U.S. border crossings. The Peace Bridge plaza on the U.S. side is a complex of roads, customs inspection areas, passport control areas, and duty-free shops. On average 5000 heavy-duty diesel trucks and 20,000 passenger cars traverse the border daily, making the plaza area a potential "hot spot" for emissions from mobile sources. In a series of winter and summer field campaigns, we measured air pollutants, including many compounds considered by the U.S. Environmental Protection Agency (EPA*) as mobile-source air toxics (MSATs), at three fixed sampling sites: on the shore of Lake Erie, approximately 500 m upwind (under predominant wind conditions) of the Peace Bridge plaza; immediately downwind of (adjacent to) the plaza; and 500 m farther downwind, into the community of west Buffalo. Pollutants sampled were particulate matter (PM) < or = 10 microm (PM10) and < or = 2.5 microm (PM2.5) in aerodynamic diameter, elemental carbon (EC), 28 elements, 25 volatile organic compounds (VOCs) including 3 carbonyls, 52 polycyclic aromatic hydrocarbons (PAHs), and 29 nitrogenated polycyclic aromatic hydrocarbons (NPAHs). Spatial patterns of counts of ultrafine particles (UFPs, particles < 0.1 microm in aerodynamic diameter) and of particle-bound PAH (pPAH) concentrations were assessed by mobile monitoring in the neighborhood adjacent to the Peace Bridge plaza using portable instruments and Global Positioning System (GPS) tracking. The study was designed to assess differences in upwind and downwind concentrations of MSATs, in areas near the Peace Bridge plaza on the U.S. side of the border. The Buffalo Peace Bridge Study featured good access to monitoring locations proximate to the plaza and in the community, which are downwind with the dominant winds from the direction of Lake Erie and southern Ontario. Samples from the lakeside Great Lakes Center (GLC), which

  1. Eight Year Climatologies from Observational (AIRS) and Model (MERRA) Data

    NASA Technical Reports Server (NTRS)

    Hearty, Thomas; Savtchenko, Andrey; Won, Young-In; Theobalk, Mike; Vollmer, Bruce; Manning, Evan; Smith, Peter; Ostrenga, Dana; Leptoukh, Greg

    2010-01-01

    We examine climatologies derived from eight years of temperature, water vapor, cloud, and trace gas observations made by the Atmospheric Infrared Sounder (AIRS) instrument flying on the Aqua satellite and compare them to similar climatologies constructed with data from a global assimilation model, the Modern Era Retrospective-Analysis for Research and Applications (MERRA). We use the AIRS climatologies to examine anomalies and trends in the AIRS data record. Since sampling can be an issue for infrared satellites in low earth orbit, we also use the MERRA data to examine the AIRS sampling biases. By sampling the MERRA data at the AIRS space-time locations both with and without the AIRS quality control we estimate the sampling bias of the AIRS climatology and the atmospheric conditions where AIRS has a lower sampling rate. While the AIRS temperature and water vapor sampling biases are small at low latitudes, they can be more than a few degrees in temperature or 10 percent in water vapor at higher latitudes. The largest sampling biases are over desert. The AIRS and MERRA data are available from the Goddard Earth Sciences Data and Information Services Center (GES DISC). The AIRS climatologies we used are available for analysis with the GIOVANNI data exploration tool. (see, http://disc.gsfc.nasa.gov).

  2. Urban Air Quality Modelling with AURORA: Prague and Bratislava

    NASA Astrophysics Data System (ADS)

    Veldeman, N.; Viaene, P.; De Ridder, K.; Peelaerts, W.; Lauwaet, D.; Muhammad, N.; Blyth, L.

    2012-04-01

    The European Commission, in its strategy to protect the health of the European citizens, states that in order to assess the impact of air pollution on public health, information on long-term exposure to air pollution should be available. Currently, indicators of air quality are often being generated using measured pollutant concentrations. While air quality monitoring stations data provide accurate time series information at specific locations, air quality models have the advantage of being able to assess the spatial variability of air quality (for different resolutions) and predict air quality in the future based on different scenarios. When running such air quality models at a high spatial and temporal resolution, one can simulate the actual situation as closely as possible, allowing for a detailed assessment of the risk of exposure to citizens from different pollutants. AURORA (Air quality modelling in Urban Regions using an Optimal Resolution Approach), a prognostic 3-dimensional Eulerian chemistry-transport model, is designed to simulate urban- to regional-scale atmospheric pollutant concentration and exposure fields. The AURORA model also allows to calculate the impact of changes in land use (e.g. planting of trees) or of emission reduction scenario's on air quality. AURORA is currently being applied within the ESA atmospheric GMES service, PASODOBLE (http://www.myair-eu.org), that delivers information on air quality, greenhouse gases, stratospheric ozone, … At present there are two operational AURORA services within PASODOBLE. Within the "Air quality forecast service" VITO delivers daily air quality forecasts for Belgium at a resolution of 5 km and for the major Belgian cities: Brussels, Ghent, Antwerp, Liege and Charleroi. Furthermore forecast services are provided for Prague, Czech Republic and Bratislava, Slovakia, both at a resolution of 1 km. The "Urban/regional air quality assessment service" provides urban- and regional-scale maps (hourly resolution

  3. Improving Air-Conditioner and Heat Pump Modeling

    SciTech Connect

    Winkler, Jon

    2012-03-02

    This presentation describes a new approach to modeling residential air conditioners and heat pumps, which allows users to model systems by specifying only the more readily-available SEER/EER/HSPF-type metrics. Manufacturer data was used to generate full sets of model inputs for over 450 heat pumps and air conditioners. A sensitivity analysis identified which inputs can be safely defaulted “behind-the-scenes” without negatively impacting the reliability of energy simulations.

  4. Improving Air-Conditioner and Heat Pump Modeling (Presentation)

    SciTech Connect

    Winkler, J.

    2012-03-01

    A new approach to modeling residential air conditioners and heat pumps allows users to model systems by specifying only the more readily-available SEER/EER/HSPF-type metrics. Manufacturer data was used to generate full sets of model inputs for over 450 heat pumps and air conditioners. A sensitivity analysis identified which inputs can be safely defaulted 'behind-the-scenes' without negatively impacting the reliability of energy simulations.

  5. Enhanced, multi criteria based site selection to measure mobile source toxic air pollutants

    EPA Science Inventory

    Research studies being conducted by the U.S. Environmental Protection Agency in collaboration with the U.S. Federal Highway Administration are designed to establish relationships between concentrations of highway vehicle air pollutants and variations in these concentrations as a ...

  6. DETECTION AND IDENTIFICATION OF TOXIC AIR POLLUTANTS USING AIRBORNE LWIR HYPERSPECTRAL IMAGING

    EPA Science Inventory

    Gaseous releases from petrochemical, refinery, and electrical production facilities can contribute to regional air quality problems. Fugitive emissions or leaks can be costly to industry in terms of lost materials and products. Ground-based sampling and monitoring for leaks are t...

  7. CO-DEPENDENCIES OF REACTIVE AIR TOXIC AND CRITERIA POLLUTANTS ON EMISSION REDUCTIONS

    EPA Science Inventory

    It is important to understand the effect of emission controls on the concentrations of ozone, PM2.5, and hazardous air pollutants simultaneously, in order to evaluate the full range of both health related and economic effects. Until recently, the capability of simultan...

  8. COMPARATIVE TOXICITY OF AIR POLLUTION PARTICLES COLLECTED FROM DIFFERENT GEOGRAPHICAL LOCATIONS

    EPA Science Inventory

    Air pollution particulate matter (PM) is responsible for more than 500,000 deaths worldwide each year. PM pollution is a complex mixture containing dozens of different compounds; the composition of PM can vary dramatically among different locations depending on the sources of pa...

  9. CHARACTERIZATION OF AIR TOXICS FROM AN OIL-FIRED FIRETUBE BOILER

    EPA Science Inventory

    Tests were conducted on a commercially available firetube package boiler running on #2 through #6 oils to determine the emissions levels of hazardous air pollutants (HAPs) from the combustion of four fuel oils. Flue gas was sampled to determine levels of volatile and semivolatile...

  10. DEMONSTRATION BULLETIN: IN-SITU STEAM/HOT AIR SOIL STRIPPING TOXIC TREATMENT (USA) INC.

    EPA Science Inventory

    This technology uses steam and hot air to strip volatile organics from contaminated soil. The treatment equipment is mobile and treats the soil in-situ without need for soil excavation or transportation. The organic contaminants volatilized from the soil are condensed and col...

  11. Recent Advances in WRF Modeling for Air Quality Applications

    EPA Science Inventory

    The USEPA uses WRF in conjunction with the Community Multiscale Air Quality (CMAQ) for air quality regulation and research. Over the years we have added physics options and geophysical datasets to the WRF system to enhance model capabilities especially for extended retrospective...

  12. Toxic volatile organic compounds in environmental tobacco smoke: Emission factors for modeling exposures of California populations

    SciTech Connect

    Daisey, J.M.; Mahanama, K.R.R.; Hodgson, A.T.

    1994-10-01

    The primary objective of this study was to measure emission factors for selected toxic air contaminants in environmental tobacco smoke (ETS) using a room-sized environmental chamber. The emissions of 23 volatile organic compounds (VOCs), including, 1,3-butadiene, three aldehydes and two vapor-phase N-nitrosamines were determined for six commercial brands of cigarettes and reference cigarette 1R4F. The commercial brands were selected to represent 62.5% of the cigarettes smoked in California. For each brand, three cigarettes were machine smoked in the chamber. The experiments were conducted over four hours to investigate the effects of aging. Emission factors of the target compounds were also determined for sidestream smoke (SS). For almost all target compounds, the ETS emission factors were significantly higher than the corresponding SS values probably due to less favorable combustion conditions and wall losses in the SS apparatus. Where valid comparisons could be made, the ETS emission factors were generally in good agreement with the literature. Therefore, the ETS emission factors, rather than the SS values, are recommended for use in models to estimate population exposures from this source. The variabilities in the emission factors ({mu}g/cigarette) of the selected toxic air contaminants among brands, expressed as coefficients of variation, were 16 to 29%. Therefore, emissions among brands were Generally similar. Differences among brands were related to the smoked lengths of the cigarettes and the masses of consumed tobacco. Mentholation and whether a cigarette was classified as light or regular did not significantly affect emissions. Aging was determined not to be a significant factor for the target compounds. There were, however, deposition losses of the less volatile compounds to chamber surfaces.

  13. Human intake fraction of toxic pollutants: a model comparison between caltox and uses-lca

    SciTech Connect

    Huijbregts, Mark A.J.; Geelen, Loes M.J.; Hertwich, Edgar G.; McKone, Thomas E.; van de Meent, Dik

    2004-01-06

    In Life Cycle Assessment and Comparative Risk Assessment potential human exposure to toxic pollutants can be expressed as the human intake fraction (iF), representing the fraction of the quantity emitted that enters the human population. To assess model uncertainty in the human intake fraction, ingestion and inhalation iFs of 367 substances emitted to air and freshwater were calculated with two commonly applied multi-media fate and exposure models, CalTOX and USES-LCA. Comparison of the model outcomes reveal that uncertainty in the ingestion iFs was up to a factor of 70. The uncertainty in the inhalation iFs was up to a factor of 865,000. The comparison showed that relatively few model differences account for the uncertainties found. An optimal model structure in the calculation of human intake fractions can be achieved by including (1) rain and no-rain scenarios, (2) a continental sea water compartment, (3) drinking water purification, (4) pH-correction of chemical properties, and (5) aerosol-associated deposition on plants. Finally, vertical stratification of the soil compartment combined with a chemical-dependent soil depth may be considered in future intake fraction calculations.

  14. Rodent models of cardiopulmonary disease: their potential applicability in studies of air pollutant susceptibility.

    PubMed Central

    Kodavanti, U P; Costa, D L; Bromberg, P A

    1998-01-01

    The mechanisms by which increased mortality and morbidity occur in individuals with preexistent cardiopulmonary disease following acute episodes of air pollution are unknown. Studies involving air pollution effects on animal models of human cardiopulmonary diseases are both infrequent and difficult to interpret. Such models are, however, extensively used in studies of disease pathogenesis. Primarily they comprise those developed by genetic, pharmacologic, or surgical manipulations of the cardiopulmonary system. This review attempts a comprehensive description of rodent cardiopulmonary disease models in the context of their potential application to susceptibility studies of air pollutants regardless of whether the models have been previously used for such studies. The pulmonary disease models include bronchitis, emphysema, asthma/allergy, chronic obstructive pulmonary disease, interstitial fibrosis, and infection. The models of systemic hypertension and congestive heart failure include: those derived by genetics (spontaneously hypertensive, Dahl S. renin transgenic, and other rodent models); congestive heart failure models derived by surgical manipulations; viral myocarditis; and cardiomyopathy induced by adriamycin. The characteristic pathogenic features critical to understanding the susceptibility to inhaled toxicants are described. It is anticipated that this review will provide a ready reference for the selection of appropriate rodent models of cardiopulmonary diseases and identify not only their pathobiologic similarities and/or differences to humans but also their potential usefulness in susceptibility studies. Images Figure 2 PMID:9539009

  15. Heme oxygenase-1 protects endothelial cells from the toxicity of air pollutant chemicals.

    PubMed

    Lawal, Akeem O; Zhang, Min; Dittmar, Michael; Lulla, Aaron; Araujo, Jesus A

    2015-05-01

    Diesel exhaust particles (DEPs) are a major component of diesel emissions, responsible for a large portion of their toxicity. In this study, we examined the toxic effects of DEPs on endothelial cells and the role of DEP-induced heme oxygenase-1 (HO-1) expression. Human microvascular endothelial cells (HMECs) were treated with an organic extract of DEPs from an automobile engine (A-DEP) or a forklift engine (F-DEP) for 1 and 4h. ROS generation, cell viability, lactate dehydrogenase leakage, expression of HO-1, inflammatory genes, cell adhesion molecules and unfolded protein respone (UPR) gene were assessed. HO-1 expression and/or activity were inhibited by siRNA or tin protoporphyrin (Sn PPIX) and enhanced by an expression plasmid or cobalt protoporphyrin (CoPPIX). Exposure to 25μg/ml of A-DEP and F-DEP significantly induced ROS production, cellular toxicity and greater levels of inflammatory and cellular adhesion molecules but to a different degree. Inhibition of HO-1 enzymatic activity with SnPPIX and silencing of the HO-1 gene by siRNA enhanced DEP-induced ROS production, further decreased cell viability and increased expression of inflammatory and cell adhesion molecules. On the other hand, overexpression of the HO-1 gene by a pcDNA 3.1D/V5-HO-1 plasmid significantly mitigated ROS production, increased cell survival and decreased the expression of inflammatory genes. HO-1 expression protected HMECs from DEP-induced prooxidative and proinflammatory effects. Modulation of HO-1 expression could potentially serve as a therapeutic target in an attempt to inhibit the cardiovascular effects of ambient PM.

  16. Dispersion modeling of selected PAHs in urban air: A new approach combining dispersion model with GIS and passive air sampling

    NASA Astrophysics Data System (ADS)

    Sáňka, Ondřej; Melymuk, Lisa; Čupr, Pavel; Dvorská, Alice; Klánová, Jana

    2014-10-01

    This study introduces a new combined air concentration measurement and modeling approach that we propose can be useful in medium and long term air quality assessment. A dispersion study was carried out for four high molecular weight polycyclic aromatic hydrocarbons (PAHs) in an urban area with industrial, traffic and domestic heating sources. A geographic information system (GIS) was used both for processing of input data as well as visualization of the modeling results. The outcomes of the dispersion model were compared to the results of passive air sampling (PAS). Despite discrepancies between measured and modeled concentrations, an approach combining the two techniques is promising for future air quality assessment. Differences between measured and modeled concentrations, in particular when measured values exceed the modeled concentrations, are indicative of undocumented, sporadic pollutant sources. Thus, these differences can also be useful for assessing and refining emission inventories.

  17. A PROBABILISTIC MODELING FRAMEWORK FOR PREDICTING POPULATION EXPOSURES TO BENZENE

    EPA Science Inventory

    The US Environmental Protection Agency (EPA) is modifying their probabilistic Stochastic Human Exposure Dose Simulation (SHEDS) model to assess aggregate exposures to air toxics. Air toxics include urban Hazardous Air Pollutants (HAPS) such as benzene from mobile sources, part...

  18. A Physically Based Model for Air-Lift Pumping

    NASA Astrophysics Data System (ADS)

    FrançOis, Odile; Gilmore, Tyler; Pinto, Michael J.; Gorelick, Steven M.

    1996-08-01

    A predictive, physically based model for pumping water from a well using air injection (air-lift pumping) was developed for the range of flow rates that we explored in a series of laboratory experiments. The goal was to determine the air flow rate required to pump a specific flow rate of water in a given well, designed for in-well air stripping of volatile organic compounds from an aquifer. The model was validated against original laboratory data as well as data from the literature. A laboratory air-lift system was constructed that consisted of a 70-foot-long (21-m-long) pipe, 5.5 inches (14 cm) inside diameter, in which an air line of 1.3 inches (3.3 cm) outside diameter was placed with its bottom at different elevations above the base of the long pipe. Experiments were conducted for different levels of submergence, with water-pumping rates ranging from 5 to 70 gallons/min (0.32-4.4 L/s), and air flow ranging from 7 to 38 standard cubic feet/min (0.2-1.1 m3 STP/min). The theoretical approach adopted in the model was based on an analysis of the system as a one-dimensional two-phase flow problem. The expression for the pressure gradient includes inertial energy terms, friction, and gas expansion versus elevation. Data analysis revealed that application of the usual drift-flux model to estimate the air void fraction is not adequate for the observed flow patterns: either slug or churn flow. We propose a modified drift-flux model that accurately predicts air-lift pumping requirements for a range of conditions representative of in-well air-stripping operations.

  19. Modeling air quality over China: Results from the Panda project

    NASA Astrophysics Data System (ADS)

    Katinka Petersen, Anna; Bouarar, Idir; Brasseur, Guy; Granier, Claire; Xie, Ying; Wang, Lili; Wang, Xuemei

    2015-04-01

    China faces strong air pollution problems related to rapid economic development in the past decade and increasing demand for energy. Air quality monitoring stations often report high levels of particle matter and ozone all over the country. Knowing its long-term health impacts, air pollution became then a pressing problem not only in China but also in other Asian countries. The PANDA project is a result of cooperation between scientists from Europe and China who joined their efforts for a better understanding of the processes controlling air pollution in China, improve methods for monitoring air quality and elaborate indicators in support of European and Chinese policies. A modeling system of air pollution is being setup within the PANDA project and include advanced global (MACC, EMEP) and regional (WRF-Chem, EMEP) meteorological and chemical models to analyze and monitor air quality in China. The poster describes the accomplishments obtained within the first year of the project. Model simulations for January and July 2010 are evaluated with satellite measurements (SCIAMACHY NO2 and MOPITT CO) and in-situ data (O3, CO, NOx, PM10 and PM2.5) observed at several surface stations in China. Using the WRF-Chem model, we investigate the sensitivity of the model performance to emissions (MACCity, HTAPv2), horizontal resolution (60km, 20km) and choice of initial and boundary conditions.

  20. Gas-fired boiler and turbine air toxics summary report. Final report, January-September 1995

    SciTech Connect

    Rossi-Lane, C.; Stein, D.; Himes, R.

    1996-08-01

    The objective of the report is to provide a summary of the criteria pollutants and hazardous air pollutants (HAPs) emitted from a variety of gas-fired stationary sources including utility boilers, utility turbines, and turbines used for natural gas transmission. The report provides emission factors for each compound measured as a function of load to support general use during the preparation of Title V permit applications.

  1. Simplified preparation of TO14 and Title III air toxic standards using a Windows software package and dynamic dilution schemes

    SciTech Connect

    Cardin, D.B.; Galoustian, E.A.

    1994-12-31

    The preparation of Air Toxic standards in the laboratory can be performed using several methods. These include injection of purge and trap standards, static dilution from pure compounds, and dynamic dilution from NIST traceable standards. A software package running under Windows has been developed that makes calculating dilution parameters for even complex mixtures fast and simple. Compound parameters such are name, molecular weight, boiling point, and density are saved in a data base for later access. Gas and liquid mixtures can be easily defined and saved as an inventory item, with preparation screens that calculate appropriate transfer volumes of each analyte. These mixtures can be utilized by both the static and dynamic dilution analysis windows to calculate proper flow rates and injection volumes for obtaining requested concentrations. A particularly useful approach for making accurate polar VOC standards will be presented.

  2. A FEDERATED PARTNERSHIP FOR URBAN METEOROLOGICAL AND AIR QUALITY MODELING

    EPA Science Inventory

    Recently, applications of urban meteorological and air quality models have been performed at resolutions on the order of km grid sizes. This necessitated development and incorporation of high resolution landcover data and additional boundary layer parameters that serve to descri...

  3. Incorporating principal component analysis into air quality model evaluation

    EPA Science Inventory

    The efficacy of standard air quality model evaluation techniques is becoming compromised as the simulation periods continue to lengthen in response to ever increasing computing capacity. Accordingly, the purpose of this paper is to demonstrate a statistical approach called Princi...

  4. A framework and plan for modeling and managing toxic chemicals in Lake Michigan

    SciTech Connect

    Richardson, W.; Endicott, D.

    1995-12-31

    Although there have been substantial reductions in loadings and subsequent concentrations of many anthropogenic chemicals in the water, sediment, and ecosystem of Lake Michigan, levels for many remain above established standards or objectives. Also, ecological impacts remain probable as, for example, Lake Michigan lake trout do not reproduce naturally. A preliminary assessment of chemical sources and fate has been completed using a screening model. For PCBs this assessment indicates levels in lake trout will remain above 1 mg/kg even if all point or watershed sources could be eliminated. This is because of estimated atmospheric interaction and exchange. Because of the major ecological and economical consequences, the screening results need to be scientifically validated. This is being done by the Great Lakes National Program Office (GLNPO) in cooperation with the Office of Research and Development (ORD) and other state and academic organizations. A workplan has been prepared for developing and testing a series of more spatially resolved models for PCBs, atrazine, mercury, and trans-nonachlor. In addition, plans include the direct coupling of air and water transport and fate models. A summary of this workplan and preliminary modeling results will be presented and related to the issues of managing toxic substances in Lake Michigan and the Great Lakes.

  5. Heme oxygenase-1 protects endothelial cells from the toxicity of air pollutant chemicals

    SciTech Connect

    Lawal, Akeem O.; Zhang, Min; Dittmar, Michael; Lulla, Aaron; Araujo, Jesus A.

    2015-05-01

    Diesel exhaust particles (DEPs) are a major component of diesel emissions, responsible for a large portion of their toxicity. In this study, we examined the toxic effects of DEPs on endothelial cells and the role of DEP-induced heme oxygenase-1 (HO-1) expression. Human microvascular endothelial cells (HMECs) were treated with an organic extract of DEPs from an automobile engine (A-DEP) or a forklift engine (F-DEP) for 1 and 4 h. ROS generation, cell viability, lactate dehydrogenase leakage, expression of HO-1, inflammatory genes, cell adhesion molecules and unfolded protein respone (UPR) gene were assessed. HO-1 expression and/or activity were inhibited by siRNA or tin protoporphyrin (Sn PPIX) and enhanced by an expression plasmid or cobalt protoporphyrin (CoPPIX). Exposure to 25 μg/ml of A-DEP and F-DEP significantly induced ROS production, cellular toxicity and greater levels of inflammatory and cellular adhesion molecules but to a different degree. Inhibition of HO-1 enzymatic activity with SnPPIX and silencing of the HO-1 gene by siRNA enhanced DEP-induced ROS production, further decreased cell viability and increased expression of inflammatory and cell adhesion molecules. On the other hand, overexpression of the HO-1 gene by a pcDNA 3.1D/V5-HO-1 plasmid significantly mitigated ROS production, increased cell survival and decreased the expression of inflammatory genes. HO-1 expression protected HMECs from DEP-induced prooxidative and proinflammatory effects. Modulation of HO-1 expression could potentially serve as a therapeutic target in an attempt to inhibit the cardiovascular effects of ambient PM. - Highlights: • We examined the role of HO-1 expression on diesel exhaust particle (DEP) in endothelial cells. • DEPs exert cytotoxic and inflammatory effects on human microvascular endothelial cells (HMECs). • DEPs induce HO-1 expression in HMECs. • HO-1 protects against the oxidative stress induced by DEps. • HO-1 attenuates the proinflammatory effects

  6. Control of asthma triggers in indoor air with air cleaners: a modeling analysis

    PubMed Central

    Myatt, Theodore A; Minegishi, Taeko; Allen, Joseph G; MacIntosh, David L

    2008-01-01

    Background Reducing exposure to environmental agents indoors shown to increase asthma symptoms or lead to asthma exacerbations is an important component of a strategy to manage asthma for individuals. Numerous investigations have demonstrated that portable air cleaning devices can reduce concentrations of asthma triggers in indoor air; however, their benefits for breathing problems have not always been reproducible. The potential exposure benefits of whole house high efficiency in-duct air cleaners for sensitive subpopulations have yet to be evaluated. Methods We used an indoor air quality modeling system (CONTAM) developed by NIST to examine peak and time-integrated concentrations of common asthma triggers present in indoor air over a year as a function of natural ventilation, portable air cleaners, and forced air ventilation equipped with conventional and high efficiency filtration systems. Emission rates for asthma triggers were based on experimental studies published in the scientific literature. Results Forced air systems with high efficiency filtration were found to provide the best control of asthma triggers: 30–55% lower cat allergen levels, 90–99% lower risk of respiratory infection through the inhalation route of exposure, 90–98% lower environmental tobacco smoke (ETS) levels, and 50–75% lower fungal spore levels than the other ventilation/filtration systems considered. These results indicate that the use of high efficiency in-duct air cleaners provide an effective means of controlling allergen levels not only in a single room, like a portable air cleaner, but the whole house. Conclusion These findings are useful for evaluating potential benefits of high efficiency in-duct filtration systems for controlling exposure to asthma triggers indoors and for the design of trials of environmental interventions intended to evaluate their utility in practice. PMID:18684328

  7. Toxic fear: the management of uncertainty in the wake of the Amsterdam air crash.

    PubMed

    Boin, A; van Duin, M; Heyse, L

    2001-12-14

    This paper examines the management of uncertainty among emergency responders, the media, and the public following the crash of an Israeli cargo plane carrying apparently hazardous cargo in Amsterdam's Bijlmermeer area. While the authorities' management of the emergency created by the initial crash was effective, the long-term crisis management performance was considerably less effective. It is argued that, particularly in hazardous materials emergencies, considerable management attention is required in the long-term aftermath rather than seeking a quick declaration of "all clear" or determination that the crisis is over. This paper examines the roles of all actors in the crisis and addresses the nature of communications in the "disaster after the disaster". The evolution of a "toxic fear" among citizens is documented and the social psychology of crisis management in the aftermath is examined. PMID:11679195

  8. Quantitative Structure--Activity Relationship Modeling of Rat Acute Toxicity by Oral Exposure

    EPA Science Inventory

    Background: Few Quantitative Structure-Activity Relationship (QSAR) studies have successfully modeled large, diverse rodent toxicity endpoints. Objective: In this study, a combinatorial QSAR approach has been employed for the creation of robust and predictive models of acute toxi...

  9. Modeling of hydrogen-air diffusion flame

    NASA Technical Reports Server (NTRS)

    Isaac, K. M.

    1989-01-01

    An analytical and computational study of opposed jet diffusion flame for the purpose of understanding the effects of contaminants in the reactants and thermal diffusion of light species on extinction and reignition of diffusion flames is in progress. The methodologies that have been attempted so far are described. Results using a simple, one-step reaction for the hydrogen-air counterflow diffusion flame are presented. These results show the correct trends in the profiles of chemical species and temperature. The extinction limit can be clearly seen in the plot of temperature vs. Damkohler number.

  10. National Emission Standard for Hazardous Air Pollutants compliance verification plan for the K-1435 Toxic Substances Control Act Incinerator

    SciTech Connect

    Ambrose, M.L.

    1986-07-28

    This documentation was prepared for submittal to the Environmental Protection Agency (EPA) in order to meet the requirements of the National Emissions Standards for Hazardous Air Pollutants (NESHAP). This document will emphasize the control of radioactive emissions from the K-1435 Toxic Substances Control Act (TSCA) Incinerator. The TSCA Incinerator is a dual purpose solid/liquid incinerator that is under construction at the Oak Ridge Gaseous Diffusion Plant to destroy radioactively contaminated polychlorinated biphenyls (PCBs) and other hazardous organic wastes in compliance with the TSCA and the Resource Conservation and Recovery Act (RCRA). These wastes are generated at the facilities managed by the Department of Energy, Oak Ridge Operations (DOE-ORO). Destruction of the PCBs and the hazardous organic wastes will be accomplished in a rotary kiln incinerator with an afterburner. The incinerator will thermally destroy the organic constituents of the liquids, solids, and sludges to produce an organically inert ash. In addition to the incinerator, an extensive off-gas treatment facility is being constructed to remove particulate and acidic gas air emissions.

  11. Scale Issues in Air Quality Modeling

    EPA Science Inventory

    This presentation reviews past model evaluation studies investigating the impact of horizontal grid spacing on model performance. It also presents several examples of using a spectral decomposition technique to separate the forcings from processes operating on different time scal...

  12. Development of quantitative interspecies toxicity relationship modeling of chemicals to fish.

    PubMed

    Fatemi, M H; Mousa Shahroudi, E; Amini, Z

    2015-09-01

    In this work, quantitative interspecies-toxicity relationship methodologies were used to improve the prediction power of interspecies toxicity model. The most relevant descriptors selected by stepwise multiple linear regressions and toxicity of chemical to Daphnia magna were used to predict the toxicities of chemicals to fish. Modeling methods that were used for developing linear and nonlinear models were multiple linear regression (MLR), random forest (RF), artificial neural network (ANN) and support vector machine (SVM). The obtained results indicate the superiority of SVM model over other models. Robustness and reliability of the constructed SVM model were evaluated by using the leave-one-out cross-validation method (Q(2)=0.69, SPRESS=0.822) and Y-randomization test (R(2)=0.268 for 30 trail). Furthermore, the chemical applicability domains of these models were determined via leverage approach. The developed SVM model was used for the prediction of toxicity of 46 compounds that their experimental toxicities to a fish were not being reported earlier from their toxicities to D. magna and relevant molecular descriptors.

  13. Expanding metal mixture toxicity models to natural stream and lake invertebrate communities

    USGS Publications Warehouse

    Balistrieri, Laurie S.; Mebane, Christopher A.; Schmidt, Travis S.; Keller, William (Bill)

    2015-01-01

    A modeling approach that was used to predict the toxicity of dissolved single and multiple metals to trout is extended to stream benthic macroinvertebrates, freshwater zooplankton, and Daphnia magna. The approach predicts the accumulation of toxicants (H, Al, Cd, Cu, Ni, Pb, and Zn) in organisms using 3 equilibrium accumulation models that define interactions between dissolved cations and biological receptors (biotic ligands). These models differ in the structure of the receptors and include a 2-site biotic ligand model, a bidentate biotic ligand or 2-pKa model, and a humic acid model. The predicted accumulation of toxicants is weighted using toxicant-specific coefficients and incorporated into a toxicity function called Tox, which is then related to observed mortality or invertebrate community richness using a logistic equation. All accumulation models provide reasonable fits to metal concentrations in tissue samples of stream invertebrates. Despite the good fits, distinct differences in the magnitude of toxicant accumulation and biotic ligand speciation exist among the models for a given solution composition. However, predicted biological responses are similar among the models because there are interdependencies among model parameters in the accumulation–Tox models. To illustrate potential applications of the approaches, the 3 accumulation–Tox models for natural stream invertebrates are used in Monte Carlo simulations to predict the probability of adverse impacts in catchments of differing geology in central Colorado (USA); to link geology, water chemistry, and biological response; and to demonstrate how this approach can be used to screen for potential risks associated with resource development.

  14. Air Leakage of U.S. Homes: Model Prediction

    SciTech Connect

    Sherman, Max H.; McWilliams, Jennifer A.

    2007-01-01

    Air tightness is an important property of building envelopes. It is a key factor in determining infiltration and related wall-performance properties such as indoor air quality, maintainability and moisture balance. Air leakage in U.S. houses consumes roughly 1/3 of the HVAC energy but provides most of the ventilation used to control IAQ. The Lawrence Berkeley National Laboratory has been gathering residential air leakage data from many sources and now has a database of more than 100,000 raw measurements. This paper uses a model developed from that database in conjunction with US Census Bureau data for estimating air leakage as a function of location throughout the US.

  15. A diagnostic model for studying daytime urban air quality trends

    NASA Technical Reports Server (NTRS)

    Brewer, D. A.; Remsberg, E. E.; Woodbury, G. E.

    1981-01-01

    A single cell Eulerian photochemical air quality simulation model was developed and validated for selected days of the 1976 St. Louis Regional Air Pollution Study (RAPS) data sets; parameterizations of variables in the model and validation studies using the model are discussed. Good agreement was obtained between measured and modeled concentrations of NO, CO, and NO2 for all days simulated. The maximum concentration of O3 was also predicted well. Predicted species concentrations were relatively insensitive to small variations in CO and NOx emissions and to the concentrations of species which are entrained as the mixed layer rises.

  16. Urban airshed modeling of air quality impacts of alternative transportation fuel use in Los Angeles and Atlanta

    SciTech Connect

    1997-12-01

    The main objective of NREL in supporting this study is to determine the relative air quality impact of the use of compressed natural gas (CNG) as an alternative transportation fuel when compared to low Reid vapor pressure (RVP) gasoline and reformulated gasoline (RFG). A table lists the criteria, air toxic, and greenhouse gas pollutants for which emissions were estimated for the alternative fuel scenarios. Air quality impacts were then estimated by performing photochemical modeling of the alternative fuel scenarios using the Urban Airshed Model Version 6.21 and the Carbon Bond Mechanism Version IV (CBM-IV) (Geary et al., 1988) Using this model, the authors examined the formation and transport of ozone under alternative fuel strategies for motor vehicle transportation sources for the year 2007. Photochemical modeling was performed for modeling domains in Los Angeles, California, and Atlanta, Georgia.

  17. Impact of inherent meteorology uncertainty on air quality model predictions

    NASA Astrophysics Data System (ADS)

    Gilliam, Robert C.; Hogrefe, Christian; Godowitch, James M.; Napelenok, Sergey; Mathur, Rohit; Rao, S. Trivikrama

    2015-12-01

    It is well established that there are a number of different classifications and sources of uncertainties in environmental modeling systems. Air quality models rely on two key inputs, namely, meteorology and emissions. When using air quality models for decision making, it is important to understand how uncertainties in these inputs affect the simulated concentrations. Ensembles are one method to explore how uncertainty in meteorology affects air pollution concentrations. Most studies explore this uncertainty by running different meteorological models or the same model with different physics options and in some cases combinations of different meteorological and air quality models. While these have been shown to be useful techniques in some cases, we present a technique that leverages the initial condition perturbations of a weather forecast ensemble, namely, the Short-Range Ensemble Forecast system to drive the four-dimensional data assimilation in the Weather Research and Forecasting (WRF)-Community Multiscale Air Quality (CMAQ) model with a key focus being the response of ozone chemistry and transport. Results confirm that a sizable spread in WRF solutions, including common weather variables of temperature, wind, boundary layer depth, clouds, and radiation, can cause a relatively large range of ozone-mixing ratios. Pollutant transport can be altered by hundreds of kilometers over several days. Ozone-mixing ratios of the ensemble can vary as much as 10-20 ppb or 20-30% in areas that typically have higher pollution levels.

  18. Biofiltration control of VOC and air toxic emissions: n-Butane and benzene

    SciTech Connect

    Allen, E.R.

    1996-12-31

    n-Butane and benzene vapors are routinely observed in urban atmospheres. Their presence in urban airsheds is of concern because of their ozone production potential as volatile organic compounds (VOCs) and/or potential toxicity. Also, these saturated hydrocarbons are representative of airborne aliphatic and aromatic compounds. Separate laboratory studies have been conducted on the biological elimination of n-butane (n-C{sub 4}H{sub 10}) and benzene (C{sub 6}H{sub 6}) from airstreams using treated compost biofilters. The removal efficiencies were found to exceed 90% for a conditioned biofilter medium and pollutant low concentrations (< 25 ppm) and zeroth order kinetics at higher concentrations (> 100 ppm), whereas benzene vapor elimination followed zeroth order kinetics at concentrations up to 200 ppm. The maximum n-butane and benzene elimination capacities observed for the compost biofilters and conditions employed were 25 and 70 g pollutant m{sup -3} h{sup -1}, respectively. 13 refs., 6 figs., 2 tabs.

  19. Characterization of air toxics from a laboratory coal-fired combustor

    SciTech Connect

    1995-04-03

    Emissions of hazardous air pollutants from coal combustion were studied in a laboratory-scale combustion facility, with emphasis on fine particles in three size ranges of less than 7.5 {mu}m diameter. Vapors were also measured. Substances under study included organic compounds, anions, elements, and radionuclides. Fly ash was generated by firing a bituminous coal in a combuster for 40 h at each of two coal feed rates. Flue gas was sampled under two conditions. Results for organic compounds, anions, and elements show a dependence on particle size consistent with published power plant data. Accumulation of material onto surface layers was inferred from differences in chemical composition between the plume simulating dilution sampler and hot flue samples. Extracts of organic particulate material were fractionated into different polarity fractions and analyzed by GC/MS. In Phase II, these laboratory results will be compared to emissions from a full-scale power plant burning the same coal.

  20. Emissions of air toxics from a simulated charcoal kiln. Final report, October 1997--September 1998

    SciTech Connect

    Lemieux, P.M.

    1999-06-01

    The report gives results of experiments in a laboratory-scale charcoal kiln simulator to evaluate emissions of hazardous air pollutants from the production of charcoal in Missouri-type kilns. Fixed combustion gases were measured using continuous monitors. In addition, other pollutants, including methanol, volatile organic compounds, semivolatile organic compounds, and particle emission rates and size distributions were measured using various techniques. Emissions of all pollutants are reported in units of grams emitted per unit mass of initial wood converted to charcoal. Two burn conditions--slow and fast--were examined. High levels of methanol, benzene, and fine particulate were emitted in all tests. The estimated emissions from the fast burn conditions were significantly higher than those from the slow burn conditions.

  1. Emissions of air toxics from the production of charcoal in a simulated Missouri charcoal kiln

    SciTech Connect

    Lemieux, P.M.; Kariher, P.H.; Fairless, B.J.; Tapp, J.A.

    1998-11-01

    The paper gives results of experiments in a laboratory-scale charcoal kiln simulator to evaluate emissions of hazardous air pollutant from the production of charcoal in Missouri-type kilns. Fixed combustion gases were measured using continuous monitors. In addition, other pollutants, including methanol, volatile organic compounds, semivolatile organic compounds, and particle emission rates and size distributions were measured using various techniques. Emissions of all pollutants are reported in grams emitted per unit mass of initial wood converted to charcoal. Two burn conditions--slow and fast burn--were examined. High levels of methanol, benzene, and fine particulate were emitted from all tests. The estimated emissions from the fast burn conditions were significantly higher than those from the slow burn conditions.

  2. Auditing of sampling methods for air toxics at coal-fired power plants

    SciTech Connect

    Agbede, R.O.; Clements, J.L.; Grunebach, M.G.

    1995-11-01

    Advanced Technology Systems, Inc. (ATS) with subcontract assistance from international Technology Corporation (IT) has provided external audit activities for Phase II of the Department of Energy-Pittsburgh Energy Technology Center`s air emission test program. The objective of the audits is to help ensure that the data obtained from the emission tests are precise, accurate, representative, scientifically sound and legally defensible. This paper presents the criteria that were used to perform the external audits of the emission test program. It also describes the approach used by ATS and It in performing their audits. Examples of findings of the audits along with the actions take to correct problems and the subsequent effect of those actions on the test data are presented. The results of audit spikes performed at the Plant 1 test site are also discussed.

  3. Sampling of power plant stacks for air toxic emissions: Topical report for Phases 1 and 2

    SciTech Connect

    1995-02-21

    Under contract with the US Department of Energy (DE-AC22-92PCO0367), Pittsburgh Energy Technology Center, Radian Corporation has conducted a test program to collect and analyze size-fractionated stack gas particulate samples for selected inorganic hazardous air pollutants (HAPS). Specific goals of the program are (1) the collection of one-gram quantities of size-fractionated stack gas particulate matter for bulk (total) and surface chemical charactization, and (2) the determination of the relationship between particle size, bulk and surface (leachable) composition, and unit load. The information obtained from this program identifies the effects of unit load, particle size, and wet FGD system operation on the relative toxicological effects of exposure to particulate emissions.

  4. The ASAC Air Carrier Investment Model (Third Generation)

    NASA Technical Reports Server (NTRS)

    Wingrove, Earl R., III; Gaier, Eric M.; Santmire, Tara E.

    1998-01-01

    To meet its objective of assisting the U.S. aviation industry with the technological challenges of the future, NASA must identify research areas that have the greatest potential for improving the operation of the air transportation system. To accomplish this, NASA is building an Aviation System Analysis Capability (ASAC). The ASAC differs from previous NASA modeling efforts in that the economic behavior of buyers and sellers in the air transportation and aviation industries is central to its conception. To link the economics of flight with the technology of flight, ASAC requires a parametrically based model with extensions that link airline operations and investments in aircraft with aircraft characteristics. This model also must provide a mechanism for incorporating air travel demand and profitability factors into the airlines' investment decisions. Finally, the model must be flexible and capable of being incorporated into a wide-ranging suite of economic and technical models flat are envisioned for ASAC.

  5. THE FUTURE OF COMPUTER-BASED TOXICITY PREDICTION: MECHANISM-BASED MODELS VS. INFORMATION MINING APPROACHES

    EPA Science Inventory


    The Future of Computer-Based Toxicity Prediction:
    Mechanism-Based Models vs. Information Mining Approaches

    When we speak of computer-based toxicity prediction, we are generally referring to a broad array of approaches which rely primarily upon chemical structure ...

  6. EFFECTS OF WATER CHEMISTRY ON COPPER TOXICITY - WHAT'S MISSING FROM CURRENT MODELS?

    EPA Science Inventory

    Current models for the acute toxicity of cationic metals to aquatic organisms focus on the binding of free metal ions to gill surfaces. This binding, and the resultant toxicity, can be reduced by metal-complexing ligands in the exposure water, which lower the activity of the free...

  7. MODELING APPROACHES FOR ESTIMATING THE DOSIMETRY OF INHALED TOXICANTS IN CHILDREN

    EPA Science Inventory

    Risk assessment of inhaled toxicants has typically focused upon adults, with modeling used to extrapolate dosimetry and risks from laboratory animals to humans. However, behavioral factors such as time spent playing outdoors can lead to more exposure to inhaled toxicants in chil...

  8. Development of biotic ligand models for chronic manganese toxicity to fish, invertebrates, and algae.

    PubMed

    Peters, Adam; Lofts, Stephen; Merrington, Graham; Brown, Bruce; Stubblefield, William; Harlow, Keven

    2011-11-01

    Ecotoxicity tests were performed with fish, invertebrates, and algae to investigate the effect of water quality parameters on Mn toxicity. Models were developed to describe the effects of Mn as a function of water quality. Calcium (Ca) has a protective effect on Mn toxicity for both fish and invertebrates, and magnesium (Mg) also provides a protective effect for invertebrates. Protons have a protective effect on Mn toxicity to algae. The models derived are consistent with models of the toxicity of other metals to aquatic organisms in that divalent cations can act as competitors to Mn toxicity in fish and invertebrates, and protons act as competitors to Mn toxicity in algae. The selected models are able to predict Mn toxicity to the test organisms to within a factor of 2 in most cases. Under low-pH conditions invertebrates are the most sensitive taxa, and under high-pH conditions algae are most sensitive. The point at which algae become more sensitive than invertebrates depends on the Ca concentration and occurs at higher pH when Ca concentrations are low, because of the sensitivity of invertebrates under these conditions. Dissolved organic carbon concentrations have very little effect on the toxicity of Mn to aquatic organisms.

  9. Development of biotic ligand models for chronic manganese toxicity to fish, invertebrates, and algae.

    PubMed

    Peters, Adam; Lofts, Stephen; Merrington, Graham; Brown, Bruce; Stubblefield, William; Harlow, Keven

    2011-11-01

    Ecotoxicity tests were performed with fish, invertebrates, and algae to investigate the effect of water quality parameters on Mn toxicity. Models were developed to describe the effects of Mn as a function of water quality. Calcium (Ca) has a protective effect on Mn toxicity for both fish and invertebrates, and magnesium (Mg) also provides a protective effect for invertebrates. Protons have a protective effect on Mn toxicity to algae. The models derived are consistent with models of the toxicity of other metals to aquatic organisms in that divalent cations can act as competitors to Mn toxicity in fish and invertebrates, and protons act as competitors to Mn toxicity in algae. The selected models are able to predict Mn toxicity to the test organisms to within a factor of 2 in most cases. Under low-pH conditions invertebrates are the most sensitive taxa, and under high-pH conditions algae are most sensitive. The point at which algae become more sensitive than invertebrates depends on the Ca concentration and occurs at higher pH when Ca concentrations are low, because of the sensitivity of invertebrates under these conditions. Dissolved organic carbon concentrations have very little effect on the toxicity of Mn to aquatic organisms. PMID:21842490

  10. 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...

  11. A new model for investigating the mortality effects of multiple air pollutants in air pollution mortality time-series studies.

    PubMed

    Roberts, Steven

    2006-03-01

    Because the U.S. Environmental Protection Agency regulates air pollutants independently, the majority of time-series studies on air pollution and mortality have focused on estimating the adverse health effects of a single pollutant. However, due to the sometimes high correlation between air pollutants, the results from studies that focus on a single air pollutant can be difficult to interpret. In addition, the high correlation between air pollutants can produce problems of interpretation for the standard method of investigating the adverse health effects due to multiple air pollutants. The standard method involves simultaneously including the multiple air pollutants in a single statistical model. Because of this, the development of new models to concurrently estimate the adverse health effects of multiple air pollutants has recently been identified as an important area of future research. In this article, a new model for disentangling the joint effects of multiple air pollutants in air pollution mortality time-series studies is introduced. This new model uses the time-series data to assign each air pollutant a weight that indicates the pollutant's contribution to the air pollution mixture that affects mortality and to estimate the effect of this air pollution mixture on mortality. This model offers an improvement in statistical estimation precision over the standard method. It also avoids problems of interpretation that can occur if the standard method is used. This new model is then illustrated by applying it to time-series data from two U.S. counties.

  12. Integration of Density Dependence and Concentration Response Models Provides an Ecologically Relevant Assessment of Populations Exposed to Toxicants

    EPA Science Inventory

    The assessment of toxic exposure on wildlife populations involves the integration of organism level effects measured in toxicity tests (e.g., chronic life cycle) and population models. These modeling exercises typically ignore density dependence, primarily because information on ...

  13. CHANGES IN LUNG FUNCTION OBSERVED IN A STUDY OF PM AND AIR TOXICS EXPOSURE TO NC HIGHWAY PATROL TROOPERS (COPP-STUDY)

    EPA Science Inventory

    Introduction: Car emissions have been identified as a major source of respirable particles. Individuals whose jobs involve being on the road, such as patrol troopers, may be exposed to high cencentrations of toxic air pollutants from vehicle emissions. This exposure might a...

  14. REAL TIME, ON-LINE CHARACTERIZATION OF DIESEL GENERATOR AIR TOXIC EMISSIONS BY RESONANCE ENHANCED MULTI-PHOTON IONIZATION TIME OF FLIGHT MASS SPECTROMETRY

    EPA Science Inventory

    The laser based resonance, enhanced multi-photon ionization time-of-flight mass spectrometry (REMPI-TOFMS) technique has been applied to the exhaust gas stream of a diesel generator to measure, in real time, concentration levels of aromatic air toxics. Volatile organic compounds ...

  15. REAL-TIME EMISSION CHARACTERIZATION OF ORGANIC AIR TOXIC POLLUTANTS DURING STEADY STATE AND TRANSIENT OPERATION OF A MEDIUM DUTY DIESEL ENGINE

    EPA Science Inventory

    An on-line monitoring method, jet resonance-enhanced multi-photon ionization (REMPI) with time-of-flight mass spectrometry (TOFMS) was used to measure emissions of organic air toxics from a medium-duty (60 kW)diesel generator during transient and steady state operations. Emission...

  16. The ASAC Air Carrier Investment Model (Second Generation)

    NASA Technical Reports Server (NTRS)

    Wingrove, Earl R., III; Johnson, Jesse P.; Sickles, Robin C.; Good, David H.

    1997-01-01

    To meet its objective of assisting the U.S. aviation industry with the technological challenges of the future, NASA must identify research areas that have the greatest potential for improving the operation of the air transportation system. To accomplish this, NASA is building an Aviation System Analysis Capability (ASAC). The ASAC differs from previous NASA modeling efforts in that the economic behavior of buyers and sellers in the air transportation and aviation industries is central to its conception. To link the economics of flight with the technology of flight, ASAC requires a parametrically based mode with extensions that link airline operations and investments in aircraft with aircraft characteristics. This model also must provide a mechanism for incorporating air travel demand and profitability factors into the airlines' investment decisions. Finally, the model must be flexible and capable of being incorporated into a wide-ranging suite of economic and technical models that are envisioned for ASAC. We describe a second-generation Air Carrier Investment Model that meets these requirements. The enhanced model incorporates econometric results from the supply and demand curves faced by U.S.-scheduled passenger air carriers. It uses detailed information about their fleets in 1995 to make predictions about future aircraft purchases. It enables analysts with the ability to project revenue passenger-miles flown, airline industry employment, airline operating profit margins, numbers and types of aircraft in the fleet, and changes in aircraft manufacturing employment under various user-defined scenarios.

  17. VIRTUAL EMBRYO: SYSTEMS MODELING IN DEVELOPMENTAL TOXICITY - Symposium: SOT 2012

    EPA Science Inventory

    High-throughput screening (HTS) studies are providing a rich source of data that can be applied to in vitro profiling of chemical compounds for biological activity and potential toxicity. Chemical profiling in ToxCast covered 965 drugs-chemicals in over 500 diverse assays testing...

  18. Exposure Space: Integrating Exposure Data and Modeling with Toxicity Information

    EPA Science Inventory

    Recent advances have been made in high-throughput (HTP) toxicity testing, e.g. from ToxCast, which will ultimately be combined with HTP predictions of exposure potential to support next-generation chemical safety assessment. Rapid exposure methods are essential in selecting chemi...

  19. Modeling interactions in major ion toxicity to Ceriodaphnia dubia (presentation)

    EPA Science Inventory

    Various anthropogenic activities can cause exposures of freshwater systems to greatly elevated concentrations of major ions (Na, K, Ca, Mg, Cl, SO4, HCO3) with widely-varying compositions. A data set on the acute toxicity of single salts and binary salt mixtures to Ceriodaphnia d...

  20. Modeling interactions in major ion toxicity to Ceriodaphnia dubia

    EPA Science Inventory

    Various anthopogenic activities can cause exposures of freshwater systems to greatly elevated concentrations of major ions (Na, K, Ca, Mg, Cl, SO4, HCO3) with widely-varying compositions. A data set on the acute toxicity of single salts and binary salt mixtures to Ceriodaphnia d...

  1. Pathway Profiling and Tissue Modeling of Developmental Toxicity

    EPA Science Inventory

    High-throughput and high-content screening (HTS-HCS) studies are providing a rich source of data that can be applied to in vitro profiling of chemical compounds for biological activity and potential toxicity. EPA’s ToxCast™ project, and the broader Tox21 consortium, in addition t...

  2. In Silico Model for Developmental Toxicity: How to Use QSAR Models and Interpret Their Results.

    PubMed

    Marzo, Marco; Roncaglioni, Alessandra; Kulkarni, Sunil; Barton-Maclaren, Tara S; Benfenati, Emilio

    2016-01-01

    Modeling developmental toxicity has been a challenge for (Q)SAR model developers due to the complexity of the endpoint. Recently, some new in silico methods have been developed introducing the possibility to evaluate the integration of existing methods by taking advantage of various modeling perspectives. It is important that the model user is aware of the underlying basis of the different models in general, as well as the considerations and assumptions relative to the specific predictions that are obtained from these different models for the same chemical. The evaluation on the predictions needs to be done on a case-by-case basis, checking the analogs (possibly using structural, physicochemical, and toxicological information); for this purpose, the assessment of the applicability domain of the models provides further confidence in the model prediction. In this chapter, we present some examples illustrating an approach to combine human-based rules and statistical methods to support the prediction of developmental toxicity; we also discuss assumptions and uncertainties of the methodology. PMID:27311466

  3. Air-quality modelling in the Lake Baikal region.

    PubMed

    Van de Vel, Karen; Mensink, Clemens; De Ridder, Koen; Deutsch, Felix; Maes, Joachim; Vliegen, Jo; Aloyan, Artash; Yermakov, Alexander; Arutyunyan, Vardan; Khodzher, Tamara; Mijling, Bas

    2010-06-01

    In this paper, we assess the status of the air quality in the Lake Baikal region which is strongly influenced by the presence of anthropogenic pollution sources. We combined the local data, with global databases, remote sensing imagery and modelling tools. This approach allows to inventorise the air-polluting sources and to quantify the air-quality concentration levels in the Lake Baikal region to a reasonable level, despite the fact that local data are scarcely available. In the simulations, we focus on the month of July 2003, as for this period, validation data are available for a number of ground-based measurement stations within the Lake Baikal region.

  4. CAirTOX, An inter-media transfer model for assessing indirect exposures to hazardous air contaminants

    SciTech Connect

    McKone, T.E.

    1994-01-01

    Risk assessment is a quantitative evaluation of information on potential health hazards of environmental contaminants and the extent of human exposure to these contaminants. As applied to toxic chemical emissions to air, risk assessment involves four interrelated steps. These are (1) determination of source concentrations or emission characteristics, (2) exposure assessment, (3) toxicity assessment, and (4) risk characterization. These steps can be carried out with assistance from analytical models in order to estimate the potential risk associated with existing and future releases. CAirTOX has been developed as a spreadsheet model to assist in making these types of calculations. CAirTOX follows an approach that has been incorporated into the CalTOX model, which was developed for the California Department of Toxic Substances Control, With CAirTOX, we can address how contaminants released to an air basin can lead to contamination of soil, food, surface water, and sediments. The modeling effort includes a multimedia transport and transformation model, exposure scenario models, and efforts to quantify uncertainty in multimedia, multiple-pathway exposure assessments. The capacity to explicitly address uncertainty has been incorporated into the model in two ways. First, the spreadsheet form of the model makes it compatible with Monte-Carlo add-on programs that are available for uncertainty analysis. Second, all model inputs are specified in terms of an arithmetic mean and coefficient of variation so that uncertainty analyses can be carried out.

  5. Air Quality Modeling in Support of the Near-Road Exposures and Effects of Urban Air Pollutants Study (NEXUS)

    EPA Science Inventory

    A major challenge in traffic-related air pollution exposure studies is the lack of information regarding pollutant exposure characterization. Air quality modeling can provide spatially and temporally varying exposure estimates for examining relationships between traffic-related a...

  6. Meteorological and air pollution modeling for an urban airport

    NASA Technical Reports Server (NTRS)

    Swan, P. R.; Lee, I. Y.

    1980-01-01

    Results are presented of numerical experiments modeling meteorology, multiple pollutant sources, and nonlinear photochemical reactions for the case of an airport in a large urban area with complex terrain. A planetary boundary-layer model which predicts the mixing depth and generates wind, moisture, and temperature fields was used; it utilizes only surface and synoptic boundary conditions as input data. A version of the Hecht-Seinfeld-Dodge chemical kinetics model is integrated with a new, rapid numerical technique; both the San Francisco Bay Area Air Quality Management District source inventory and the San Jose Airport aircraft inventory are utilized. The air quality model results are presented in contour plots; the combined results illustrate that the highly nonlinear interactions which are present require that the chemistry and meteorology be considered simultaneously to make a valid assessment of the effects of individual sources on regional air quality.

  7. Analytical model for contaminant mass removal by air sparging

    SciTech Connect

    Rabideau, A.J.; Blayden, J.M.

    1998-12-31

    An analytical model was developed to predict the removal of volatile organic compounds (VOCs) from ground water by air sparging (AS). The model treats the air sparging zone as a completely mixed reactor subject to the removal of dissolved contaminants by volatilization, advection, and first-order decay. Nonequilibrium desorption is approximated as a first-order mass transfer process. The model reproduces the tailing and rebound behavior often observed at AS sites, and would normally require the estimation of three site-specific parameters. Dimensional analysis demonstrates that predicting tailing can be interpreted in terms of kinetic desorption or diffusion of aqueous phase contaminants into discrete air channels. Related work is ongoing to test the model against field data.

  8. Sampling of power plant stacks for air toxic emissions: Final report for Phases 1 and 2

    SciTech Connect

    1995-04-28

    A test program to collect and analyze size-fractionated stack gas particulate samples for selected inorganic hazardous air pollutants (HAPs) was conducted . Specific goals of the program are (1) the collection of one-gram quantities of size-fractionated stack gas particulate matter for bulk (total) and surface chemical characterization, and (2) the determination of the relationship between particle size, bulk and surface (leachable) composition, and unit load. The information obtained from this program identifies the effects of unit load, particle size, and wet FGD system operation on the relative toxicological effects of exposure to particulate emissions. Field testing was conducted in two phases. The Phase I field program was performed over the period of August 24 through September 20, 1992, at the Tennessee Valley Authority Widows Creek Unit 8 Power Station, located near Stevenson (Jackson County), Alabama, on the Tennessee River. Sampling activities for Phase II were conducted from September 11 through October 14, 1993. Widows Creek Unit 8 is a 575-megawatt plant that uses bituminous coal averaging 3.7% sulfur and 13% ash. Downstream of the boiler, a venture wet scrubbing system is used for control of both sulfur dioxide and particulate emissions. There is no electrostatic precipitator (ESP) in this system. This system is atypical and represents only about 5% of the US utility industry. However, this site was chosen for this study because of the lack of information available for this particulate emission control system.

  9. Towards Global QSAR Model Building for Acute Toxicity: Munro Database Case Study

    PubMed Central

    Chavan, Swapnil; Nicholls, Ian A.; Karlsson, Björn C. G.; Rosengren, Annika M.; Ballabio, Davide; Consonni, Viviana; Todeschini, Roberto

    2014-01-01

    A series of 436 Munro database chemicals were studied with respect to their corresponding experimental LD50 values to investigate the possibility of establishing a global QSAR model for acute toxicity. Dragon molecular descriptors were used for the QSAR model development and genetic algorithms were used to select descriptors better correlated with toxicity data. Toxic values were discretized in a qualitative class on the basis of the Globally Harmonized Scheme: the 436 chemicals were divided into 3 classes based on their experimental LD50 values: highly toxic, intermediate toxic and low to non-toxic. The k-nearest neighbor (k-NN) classification method was calibrated on 25 molecular descriptors and gave a non-error rate (NER) equal to 0.66 and 0.57 for internal and external prediction sets, respectively. Even if the classification performances are not optimal, the subsequent analysis of the selected descriptors and their relationship with toxicity levels constitute a step towards the development of a global QSAR model for acute toxicity. PMID:25302621

  10. AN INDOOR AIR QUALITY MODEL FOR PARTICULATE MATTER

    EPA Science Inventory

    Thye paper discusses an indoor air quality (IAQ) model for particulate matter (PM). The standard for PM < 2.5 micrometers in aerodynamic diameter (PM 2.5) proposed by the U.S. EPA has produced considerable interest in indoor exposures to PM. IAQ models provide a useful tool for...

  11. Air Quality Modeling of Traffic-related Air Pollutants for the NEXUS Study

    EPA Science Inventory

    The paper presents the results of the model applications to estimate exposure metrics in support of an epidemiologic study in Detroit, Michigan. A major challenge in traffic-related air pollution exposure studies is the lack of information regarding pollutant exposure characteriz...

  12. Assessing The Policy Relevance of Regional Air Quality Models

    NASA Astrophysics Data System (ADS)

    Holloway, T.

    This work presents a framework for discussing the policy relevance of models, and regional air quality models in particular. We define four criteria: 1) The scientific status of the model; 2) Its ability to address primary environmental concerns; 3) The position of modeled environmental issues on the political agenda; and 4) The role of scientific input into the policy process. This framework is applied to current work simulating the transport of nitric acid in Asia with the ATMOS-N model, to past studies on air pollution transport in Europe with the EMEP model, and to future applications of the United States Environmental Protection Agency (US EPA) Models-3. The Lagrangian EMEP model provided critical input to the development of the 1994 Oslo and 1999 Gothenburg Protocols to the Convention on Long-Range Transbound- ary Air Pollution, as well as to the development of EU directives, via its role as a component of the RAINS integrated assessment model. Our work simulating reactive nitrogen in Asia follows the European example in part, with the choice of ATMOS-N, a regional Lagrangian model to calculate source-receptor relationships for the RAINS- Asia integrated assessment model. However, given differences between ATMOS-N and the EMEP model, as well as differences between the scientific and political cli- mates facing Europe ten years ago and Asia today, the role of these two models in the policy process is very different. We characterize the different aspects of policy relevance between these models using our framework, and consider how the current generation US EPA air quality model compares, in light of its Eulerian structure, dif- ferent objectives, and the policy context of the US.

  13. Spatial air pollution modelling for a West-African town.

    PubMed

    Gebreab, Sirak Zenebe; Vienneau, Danielle; Feigenwinter, Christian; Bâ, Hâmpaté; Cissé, Guéladio; Tsai, Ming-Yi

    2015-01-01

    Land use regression (LUR) modelling is a common approach used in European and Northern American epidemiological studies to assess urban and traffic related air pollution exposures. Studies applying LUR in Africa are lacking. A need exists to understand if this approach holds for an African setting, where urban features, pollutant exposures and data availability differ considerably from other continents. We developed a parsimonious regression model based on 48-hour nitrogen dioxide (NO2) concentrations measured at 40 sites in Kaédi, a medium sized West-African town, and variables generated in a geographic information system (GIS). Road variables and settlement land use characteristics were found to be important predictors of 48-hour NO2 concentration in the model. About 68% of concentration variability in the town was explained by the model. The model was internally validated by leave-one-out cross-validation and it was found to perform moderately well. Furthermore, its parameters were robust to sampling variation. We applied the model at 100 m pixels to create a map describing the broad spatial pattern of NO2 across Kaédi. In this research, we demonstrated the potential for LUR as a valid, cost-effective approach for air pollution modelling and mapping in an African town. If the methodology were to be adopted by environmental and public health authorities in these regions, it could provide a quick assessment of the local air pollution burden and potentially support air pollution policies and guidelines. PMID:26618306

  14. Air toxics and epigenetic effects: ozone altered microRNAs in the sputum of human subjects

    PubMed Central

    Fry, Rebecca C.; Rager, Julia E.; Bauer, Rebecca; Sebastian, Elizabeth; Peden, David B.; Jaspers, Ilona

    2014-01-01

    Ozone (O3) is a criteria air pollutant that is associated with numerous adverse health effects, including altered respiratory immune responses. Despite its deleterious health effects, possible epigenetic mechanisms underlying O3-induced health effects remain understudied. MicroRNAs (miRNAs) are epigenetic regulators of genomic response to environmental insults and unstudied in relationship to O3 inhalation exposure. Our objective was to test whether O3 inhalation exposure significantly alters miRNA expression profiles within the human bronchial airways. Twenty healthy adult human volunteers were exposed to 0.4 ppm O3 for 2 h. Induced sputum samples were collected from each subject 48 h preexposure and 6 h postexposure for evaluation of miRNA expression and markers of inflammation in the airways. Genomewide miRNA expression profiles were evaluated by microarray analysis, and in silico predicted mRNA targets of the O3-responsive miRNAs were identified and validated against previously measured O3-induced changes in mRNA targets. Biological network analysis was performed on the O3-associated miRNAs and mRNA targets to reveal potential associated response signaling and functional enrichment. Expression analysis of the sputum samples revealed that O3 exposure significantly increased the expression levels of 10 miRNAs, namely miR-132, miR-143, miR-145, miR-199a*, miR-199b-5p, miR-222, miR-223, miR-25, miR-424, and miR-582-5p. The miRNAs and their predicted targets were associated with a diverse range of biological functions and disease signatures, noted among them inflammation and immune-related disease. The present study shows that O3 inhalation exposure disrupts select miRNA expression profiles that are associated with inflammatory and immune response signaling. These findings provide novel insight into epigenetic regulation of responses to O3 exposure. PMID:24771714

  15. An updated model for millimeter wave propagation in moist air

    NASA Astrophysics Data System (ADS)

    Liebe, H. J.

    1985-10-01

    A practical atmospheric Millimeter-Wave Propagation Model is formulated that predicts attenuation, delay, and noise properties of moist air for frequencies up to 1000 GHz. Input variables are height distributions (0-30 km) of pressure, temperature, humidity, and suspended droplet concentration along an anticipated radio path. Spectroscopic data consists of more than 450 parameters describing local O2 and H2O absorption lines complemented by continuum spectra for dry air, water vapor, and hydrosols. For a model limited to frequencies below GHz, the number of spectroscopic parameters can be reduced to less than 200. Recent laboratory measurements at 138 GHz absolute attenuation rates for simulated air with water vapor pressures up to saturation allow the formulation of an improved, though empirical water vapor continuum. Model predictions are compared with selected (2.5-430 GHz) data from both laboratory and field experiments. In general, good agreement is obtained.

  16. Mathematical model of an air-filled alpha stirling refrigerator

    NASA Astrophysics Data System (ADS)

    McFarlane, Patrick; Semperlotti, Fabio; Sen, Mihir

    2013-10-01

    This work develops a mathematical model for an alpha Stirling refrigerator with air as the working fluid and will be useful in optimizing the mechanical design of these machines. Two pistons cyclically compress and expand air while moving sinusoidally in separate chambers connected by a regenerator, thus creating a temperature difference across the system. A complete non-linear mathematical model of the machine, including air thermodynamics, and heat transfer from the walls, as well as heat transfer and fluid resistance in the regenerator, is developed. Non-dimensional groups are derived, and the mathematical model is numerically solved. The heat transfer and work are found for both chambers, and the coefficient of performance of each chamber is calculated. Important design parameters are varied and their effect on refrigerator performance determined. This sensitivity analysis, which shows what the significant parameters are, is a useful tool for the design of practical Stirling refrigeration systems.

  17. Period adding cascades: experiment and modeling in air bubbling.

    PubMed

    Pereira, Felipe Augusto Cardoso; Colli, Eduardo; Sartorelli, José Carlos

    2012-03-01

    Period adding cascades have been observed experimentally/numerically in the dynamics of neurons and pancreatic cells, lasers, electric circuits, chemical reactions, oceanic internal waves, and also in air bubbling. We show that the period adding cascades appearing in bubbling from a nozzle submerged in a viscous liquid can be reproduced by a simple model, based on some hydrodynamical principles, dealing with the time evolution of two variables, bubble position and pressure of the air chamber, through a system of differential equations with a rule of detachment based on force balance. The model further reduces to an iterating one-dimensional map giving the pressures at the detachments, where time between bubbles come out as an observable of the dynamics. The model has not only good agreement with experimental data, but is also able to predict the influence of the main parameters involved, like the length of the hose connecting the air supplier with the needle, the needle radius and the needle length.

  18. 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.

  19. Integration into Big Data: First Steps to Support Reuse of Comprehensive Toxicity Model Modules (SOT)

    EPA Science Inventory

    Data surrounding the needs of human disease and toxicity modeling are largely siloed limiting the ability to extend and reuse modules across knowledge domains. Using an infrastructure that supports integration across knowledge domains (animal toxicology, high-throughput screening...

  20. ESTIMATION OF CHEMICAL TOXICITY TO WILDLIFE SPECIES USING INTERSPECIES CORRELATION MODELS

    EPA Science Inventory

    Ecological risks to wildlife are typically assessed using toxicity data for relataively few species and with limited understanding of differences in species sensitivity to contaminants. Empirical interspecies correlation models were derived from LD50 values for 49 wildlife speci...

  1. Joint space-time geostatistical model for air quality surveillance

    NASA Astrophysics Data System (ADS)

    Russo, A.; Soares, A.; Pereira, M. J.

    2009-04-01

    Air pollution and peoples' generalized concern about air quality are, nowadays, considered to be a global problem. Although the introduction of rigid air pollution regulations has reduced pollution from industry and power stations, the growing number of cars on the road poses a new pollution problem. Considering the characteristics of the atmospheric circulation and also the residence times of certain pollutants in the atmosphere, a generalized and growing interest on air quality issues led to research intensification and publication of several articles with quite different levels of scientific depth. As most natural phenomena, air quality can be seen as a space-time process, where space-time relationships have usually quite different characteristics and levels of uncertainty. As a result, the simultaneous integration of space and time is not an easy task to perform. This problem is overcome by a variety of methodologies. The use of stochastic models and neural networks to characterize space-time dispersion of air quality is becoming a common practice. The main objective of this work is to produce an air quality model which allows forecasting critical concentration episodes of a certain pollutant by means of a hybrid approach, based on the combined use of neural network models and stochastic simulations. A stochastic simulation of the spatial component with a space-time trend model is proposed to characterize critical situations, taking into account data from the past and a space-time trend from the recent past. To identify near future critical episodes, predicted values from neural networks are used at each monitoring station. In this paper, we describe the design of a hybrid forecasting tool for ambient NO2 concentrations in Lisbon, Portugal.

  2. Reduced Life Expectancy Model for Effects of Long Term Exposure on Lethal Toxicity with Fish

    PubMed Central

    Yu, Qiming J.; Connell, Des W.

    2013-01-01

    A model based on the concept of reduction in life expectancy (RLE model) as a result of long term exposure to toxicant has been developed which has normal life expectancy (NLT) as a fixed limiting point for a species. The model is based on the equation (LC50 = a ln(LT50) + b) where a and b are constants. It was evaluated by plotting ln LT50 against LC50 with data on organic toxicants obtained from the scientific literature. Linear relationships between LC50 and ln LT50 were obtained and a Calculated NLT was derived from the plots. The Calculated NLT obtained was in good agreement with the Reported NLT obtained from the literature. Estimation of toxicity at any exposure time and concentration is possible using the model. The use of NLT as a reference point is important since it provides a data point independent of the toxicity data set and limits the data to the range where toxicity occurs. This novel approach, which represents a departure from Haber's rule, can be used to estimate long term toxicity from limited available acute toxicity data for fish exposed to organic biocides. PMID:24455314

  3. Real-Time Cell-Electronic Sensing of Coal Fly Ash Particulate Matter for Toxicity-Based Air Quality Monitoring.

    PubMed

    Moe, Birget; Yuan, Chungang; Li, Jinhua; Du, Haiying; Gabos, Stephan; Le, X Chris; Li, Xing-Fang

    2016-06-20

    The development of a unique bioassay for cytotoxicity analysis of coal fly ash (CFA) particulate matter (PM) and its potential application for air quality monitoring is described. Using human cell lines, A549 and SK-MES-1, as live probes on microelectrode-embedded 96-well sensors, impedance changes over time are measured as cells are treated with varying concentrations (1 μg/mL-20 mg/mL) of CFA samples. A dose-dependent impedance change is determined for each CFA sample, from which an IC50 histogram is obtained. The assay was successfully applied to examine CFA samples collected from three coal-fired power plants (CFPs) in China. The samples were separated into three size fractions: PM2.5 (<2.5 μm), PM10-2.5 (2.5 μm < x < 10 μm), and PM10 (>10 μm). Dynamic cell-response profiles and temporal IC50 histograms of all samples show that CFA cytotoxicity depends on concentration, exposure time (0-60 h), and cell-type (SK-MES-1 > A549). The IC50 values differentiate the cytotoxicity of CFA samples based on size fraction (PM2.5 ≈ PM10-2.5 ≫ PM10) and the sampling location (CFP2 > CFP1 ≈ CFP3). Differential cytotoxicity measurements of particulates in human cell lines using cell-electronic sensing provide a useful tool for toxicity-based air quality monitoring and risk assessment. PMID:27124590

  4. Modeling urban air pollution with optimized hierarchical fuzzy inference system.

    PubMed

    Tashayo, Behnam; Alimohammadi, Abbas

    2016-10-01

    Environmental exposure assessments (EEA) and epidemiological studies require urban air pollution models with appropriate spatial and temporal resolutions. Uncertain available data and inflexible models can limit air pollution modeling techniques, particularly in under developing countries. This paper develops a hierarchical fuzzy inference system (HFIS) to model air pollution under different land use, transportation, and meteorological conditions. To improve performance, the system treats the issue as a large-scale and high-dimensional problem and develops the proposed model using a three-step approach. In the first step, a geospatial information system (GIS) and probabilistic methods are used to preprocess the data. In the second step, a hierarchical structure is generated based on the problem. In the third step, the accuracy and complexity of the model are simultaneously optimized with a multiple objective particle swarm optimization (MOPSO) algorithm. We examine the capabilities of the proposed model for predicting daily and annual mean PM2.5 and NO2 and compare the accuracy of the results with representative models from existing literature. The benefits provided by the model features, including probabilistic preprocessing, multi-objective optimization, and hierarchical structure, are precisely evaluated by comparing five different consecutive models in terms of accuracy and complexity criteria. Fivefold cross validation is used to assess the performance of the generated models. The respective average RMSEs and coefficients of determination (R (2)) for the test datasets using proposed model are as follows: daily PM2.5 = (8.13, 0.78), annual mean PM2.5 = (4.96, 0.80), daily NO2 = (5.63, 0.79), and annual mean NO2 = (2.89, 0.83). The obtained results demonstrate that the developed hierarchical fuzzy inference system can be utilized for modeling air pollution in EEA and epidemiological studies.

  5. Development of a new toxic-unit model for the bioassessment of metals in streams

    USGS Publications Warehouse

    Schmidt, T.S.; Clements, W.H.; Mitchell, K.A.; Church, S.E.; Wanty, R.B.; Fey, D.L.; Verplanck, P.L.; San, Juan C.A.

    2010-01-01

    Two toxic-unit models that estimate the toxicity of trace-metal mixtures to benthic communities were compared. The chronic criterion accumulation ratio (CCAR), a modification of biotic ligand model (BLM) outputs for use as a toxic-unit model, accounts for the modifying and competitive influences of major cations (Ca2+, Mg2+, Na+, K+, H+), anions (HCO3−, CO32−,SO42−, Cl−, S2−) and dissolved organic carbon (DOC) in determining the free metal ion available for accumulation on the biotic ligand. The cumulative criterion unit (CCU) model, an empirical statistical model of trace-metal toxicity, considers only the ameliorative properties of Ca2+ and Mg2+ (hardness) in determining the toxicity of total dissolved trace metals. Differences in the contribution of a metal (e.g., Cu, Cd, Zn) to toxic units as determined by CCAR or CCU were observed and attributed to how each model incorporates the influences of DOC, pH, and alkalinity. Akaike information criteria demonstrate that CCAR is an improved predictor of benthic macroinvertebrate community metrics as compared with CCU. Piecewise models depict great declines (thresholds) in benthic macroinvertebrate communities at CCAR of 1 or more, while negative changes in benthic communities were detected at a CCAR of less than 1. We observed a 7% reduction in total taxa richness and a 43% decrease in Heptageniid abundance between background (CCAR = 0.1) and the threshold of chronic toxicity on the basis of continuous chronic criteria (CCAR = 1). In this first application of the BLM as a toxic-unit model, we found it superior to CCU.

  6. Development of a new toxic-unit model for the bioassessment of metals in streams.

    PubMed

    Schmidt, Travis S; Clements, William H; Mitchell, Katharine A; Church, Stanley E; Wanty, Richard B; Fey, David L; Verplanck, Philip L; San Juan, Carma A

    2010-11-01

    Two toxic-unit models that estimate the toxicity of trace-metal mixtures to benthic communities were compared. The chronic criterion accumulation ratio (CCAR), a modification of biotic ligand model (BLM) outputs for use as a toxic-unit model, accounts for the modifying and competitive influences of major cations (Ca²(+), Mg²(+), Na(+), K(+), H(+)), anions (HCO₃⁻, CO²⁻₃ ,SO²⁻₄, Cl⁻, S²⁻) and dissolved organic carbon (DOC) in determining the free metal ion available for accumulation on the biotic ligand. The cumulative criterion unit (CCU) model, an empirical statistical model of trace-metal toxicity, considers only the ameliorative properties of Ca²(+) and Mg²(+) (hardness) in determining the toxicity of total dissolved trace metals. Differences in the contribution of a metal (e.g., Cu, Cd, Zn) to toxic units as determined by CCAR or CCU were observed and attributed to how each model incorporates the influences of DOC, pH, and alkalinity. Akaike information criteria demonstrate that CCAR is an improved predictor of benthic macroinvertebrate community metrics as compared with CCU. Piecewise models depict great declines (thresholds) in benthic macroinvertebrate communities at CCAR of 1 or more, while negative changes in benthic communities were detected at a CCAR of less than 1. We observed a 7% reduction in total taxa richness and a 43% decrease in Heptageniid abundance between background (CCAR = 0.1) and the threshold of chronic toxicity on the basis of continuous chronic criteria (CCAR = 1). In this first application of the BLM as a toxic-unit model, we found it superior to CCU.

  7. Microbial toxicity of mixtures of organic chemicals in soil medium-experimental protocol and modeling

    SciTech Connect

    Arulgnanendran, V.R.J.; Khandan, N.N.

    1995-12-31

    A laboratory procedure was developed to measure the microbial toxicity in soils using respirometric technique. The procedure was tested on 35 organic chemicals and several 8- and 10- component equitoxic mixtures. The chemicals assayed in this study were found to act jointly by simple addition. A modeling approach incorporating partitioning, sorption and Quantitative Structure Activity Relationship (QSAR) techniques was developed to estimate single chemical and mixture toxicity. This modeling approach was validated using an external testing set of data.

  8. Exploring BSEP inhibition-mediated toxicity with a mechanistic model of drug-induced liver injury

    PubMed Central

    Woodhead, Jeffrey L.; Yang, Kyunghee; Siler, Scott Q.; Watkins, Paul B.; Brouwer, Kim L. R.; Barton, Hugh A.; Howell, Brett A.

    2014-01-01

    Inhibition of the bile salt export pump (BSEP) has been linked to incidence of drug-induced liver injury (DILI), presumably by the accumulation of toxic bile acids in the liver. We have previously constructed and validated a model of bile acid disposition within DILIsym®, a mechanistic model of DILI. In this paper, we use DILIsym® to simulate the DILI response of the hepatotoxic BSEP inhibitors bosentan and CP-724,714 and the non-hepatotoxic BSEP inhibitor telmisartan in humans in order to explore whether we can predict that hepatotoxic BSEP inhibitors can cause bile acid accumulation to reach toxic levels. We also simulate bosentan in rats in order to illuminate potential reasons behind the lack of toxicity in rats compared to the toxicity observed in humans. DILIsym® predicts that bosentan, but not telmisartan, will cause mild hepatocellular ATP decline and serum ALT elevation in a simulated population of humans. The difference in hepatotoxic potential between bosentan and telmisartan is consistent with clinical observations. However, DILIsym® underpredicts the incidence of bosentan toxicity. DILIsym® also predicts that bosentan will not cause toxicity in a simulated population of rats, and that the difference between the response to bosentan in rats and in humans is primarily due to the less toxic bile acid pool in rats. Our simulations also suggest a potential synergistic role for bile acid accumulation and mitochondrial electron transport chain (ETC) inhibition in producing the observed toxicity in CP-724,714, and suggest that CP-724,714 metabolites may also play a role in the observed toxicity. Our work also compares the impact of competitive and noncompetitive BSEP inhibition for CP-724,714 and demonstrates that noncompetitive inhibition leads to much greater bile acid accumulation and potential toxicity. Our research demonstrates the potential for mechanistic modeling to contribute to the understanding of how bile acid transport inhibitors cause DILI

  9. AQA - Air Quality model for Austria - Evaluation and Developments

    NASA Astrophysics Data System (ADS)

    Hirtl, M.; Krüger, B. C.; Baumann-Stanzer, K.; Skomorowski, P.

    2009-04-01

    The regional weather forecast model ALADIN of the Central Institute for Meteorology and Geodynamics (ZAMG) is used in combination with the chemical transport model CAMx (www.camx.com) to conduct forecasts of gaseous and particulate air pollution over Europe. The forecasts which are done in cooperation with the University of Natural Resources and Applied Life Sciences in Vienna (BOKU) are supported by the regional governments since 2005 with the main interest on the prediction of tropospheric ozone. The daily ozone forecasts are evaluated for the summer 2008 with the observations of about 150 air quality stations in Austria. In 2008 the emission-model SMOKE was integrated into the modelling system to calculate the biogenic emissions. The anthropogenic emissions are based on the newest EMEP data set as well as on regional inventories for the core domain. The performance of SMOKE is shown for a summer period in 2007. In the frame of the COST-action 728 „Enhancing mesoscale meteorological modelling capabilities for air pollution and dispersion applications", multi-model ensembles are used to conduct an international model evaluation. The model calculations of meteorological- and concentration fields are compared to measurements on the ensemble platform at the Joint Research Centre (JRC) in Ispra. The results for 2 episodes in 2006 show the performance of the different models as well as of the model ensemble.

  10. Air Quality Model System For The Vienna/bratislava Region

    NASA Astrophysics Data System (ADS)

    Krüger, B. C.; Schmittner, W.; Kromp-Kolb, H.

    A model system has been build up, consisting of the mesoscale meteorological fore- cast model MM5 and the chemical air-quality model CAMx. The coarse grid covers central Europe. By nesting, a spatial resolution of 3 km is reached for the core area, which includes the cities of Vienna (Austria) and Bratislava (Slovakia). In a first approach, the model system has been applied to a 6-day period in Febru- ary 1997, which was characterized by stagnant meteorological conditions. During this episode, primary pollutants like CO and NO2 have been compared with ambient mea- surements for the validation of the new model system. In the future it is foreseen to improve the spatial resolution, to apply the model system also for ozone and particulates, and to utilize it for a short-time forecast of air-quality parameters.

  11. Modeling the Environmental Impact of Air Traffic Operations

    NASA Technical Reports Server (NTRS)

    Chen, Neil

    2011-01-01

    There is increased interest to understand and mitigate the impacts of air traffic on the climate, since greenhouse gases, nitrogen oxides, and contrails generated by air traffic can have adverse impacts on the climate. The models described in this presentation are useful for quantifying these impacts and for studying alternative environmentally aware operational concepts. These models have been developed by leveraging and building upon existing simulation and optimization techniques developed for the design of efficient traffic flow management strategies. Specific enhancements to the existing simulation and optimization techniques include new models that simulate aircraft fuel flow, emissions and contrails. To ensure that these new models are beneficial to the larger climate research community, the outputs of these new models are compatible with existing global climate modeling tools like the FAA's Aviation Environmental Design Tool.

  12. Modeling of membrane processes for air revitalization and water recovery

    NASA Technical Reports Server (NTRS)

    Lange, Kevin E.; Foerg, Sandra L.; Dall-Bauman, Liese A.

    1992-01-01

    Gas-separation and reverse-osmosis membrane models are being developed in conjunction with membrane testing at NASA JSC. The completed gas-separation membrane model extracts effective component permeabilities from multicomponent test data, and predicts the effects of flow configuration, operating conditions, and membrane dimensions on module performance. Variable feed- and permeate-side pressures are considered. The model has been applied to test data for hollow-fiber membrane modules with simulated cabin-air feeds. Results are presented for a membrane designed for air drying applications. Extracted permeabilities are used to predict the effect of operating conditions on water enrichment in the permeate. A first-order reverse-osmosis model has been applied to test data for spiral wound membrane modules with a simulated hygiene water feed. The model estimates an effective local component rejection coefficient under pseudosteady-state conditions. Results are used to define requirements for a detailed reverse-osmosis model.

  13. Mathematical models for predicting indoor air quality from smoking activity.

    PubMed Central

    Ott, W R

    1999-01-01

    Much progress has been made over four decades in developing, testing, and evaluating the performance of mathematical models for predicting pollutant concentrations from smoking in indoor settings. Although largely overlooked by the regulatory community, these models provide regulators and risk assessors with practical tools for quantitatively estimating the exposure level that people receive indoors for a given level of smoking activity. This article reviews the development of the mass balance model and its application to predicting indoor pollutant concentrations from cigarette smoke and derives the time-averaged version of the model from the basic laws of conservation of mass. A simple table is provided of computed respirable particulate concentrations for any indoor location for which the active smoking count, volume, and concentration decay rate (deposition rate combined with air exchange rate) are known. Using the indoor ventilatory air exchange rate causes slightly higher indoor concentrations and therefore errs on the side of protecting health, since it excludes particle deposition effects, whereas using the observed particle decay rate gives a more accurate prediction of indoor concentrations. This table permits easy comparisons of indoor concentrations with air quality guidelines and indoor standards for different combinations of active smoking counts and air exchange rates. The published literature on mathematical models of environmental tobacco smoke also is reviewed and indicates that these models generally give good agreement between predicted concentrations and actual indoor measurements. PMID:10350523

  14. Mathematical model of one-man air revitalization system

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A mathematical model was developed for simulating the steady state performance in electrochemical CO2 concentrators which utilize (NMe4)2 CO3 (aq.) electrolyte. This electrolyte, which accommodates a wide range of air relative humidity, is most suitable for one-man air revitalization systems. The model is based on the solution of coupled nonlinear ordinary differential equations derived from mass transport and rate equations for the processes which take place in the cell. The boundary conditions are obtained by solving the mass and energy transport equations. A shooting method is used to solve the differential equations.

  15. Modeling Air Stripping of Ammonia in an Agitated Vessel

    SciTech Connect

    Kofi, Adu-Wusu; Martino, Christopher J.; Wilmarth, William R.; Bennett, William M.; Peters, Robert s.

    2005-11-29

    A model has been developed to predict the rate of removal of ammonia (NH{sub 3}) from solution in a sparged agitated vessel. The model is first-order with respect to liquid-phase concentration of NH{sub 3}. The rate constant for the first-order equation is a function of parameters related to the vessel/impeller characteristics, the air/liquid properties as well as the process conditions. However, the vessel/impeller characteristics, the air/liquid properties, and the process conditions reduce the rate constant dependence to only three parameters, namely, the air sparge rate, the liquid volume or batch size, and the Henry's law constant of NH{sub 3} for the liquid or solution. Thus, the rate of removal is not mass-transfer limited. High air sparge rates, high temperatures, and low liquid volumes or batch sizes increase the rate of removal of NH{sub 3} from solution. The Henry's law constant effect is somewhat reflected in the temperature since Henry's law constant increases with increasing temperature. Data obtained from actual air stripping operation agree fairly well with the model predictions.

  16. New toxics, new poverty: a social understanding of the freebase cocaine/Paco in Buenos Aires, Argentina.

    PubMed

    Epele, María E

    2011-01-01

    Included within the field of research on changes in drug use patterns and vulnerability are conditions of emergency related to economic crisis, wars, and political conflict. This study addresses the complex connections between the rapid propagation of freebase cocaine (FBC)-locally known as "pasta base" or "Paco" in Argentina and the normalization of the consequences of Argentina's 2001-2002 political-economic crisis. On the basis of the results of an ethnographic study carried out in three neighborhoods of the Greater Buenos Aires area between 2001 and 2005, this article aims to analyze how changes in the material and social living conditions are interrelated with the high toxicity of FBC/Paco and engender the emerging compulsion of its consumption and deterioration to the bodies, subjectivities, and social activities of active drug users from these shantytowns. By analyzing the changes in transactions directly or indirectly involving drugs-specifically those ranging from cocaine to FBC/Paco-we can argue how structural poverty, "new poverty," is not only associated with the expansion of FBC/Paco but is also shaped by its use, modes of consumption, associated health problems, and sufferings.

  17. Probabilistic ecological risk assessment of effluent toxicity of a wastewater reclamation plant based on process modeling.

    PubMed

    Zeng, Siyu; Huang, Yunqing; Sun, Fu; Li, Dan; He, Miao

    2016-09-01

    The growing use of reclaimed wastewater for environmental purposes such as stream flow augmentation requires comprehensive ecological risk assessment and management. This study applied a system analysis approach, regarding a wastewater reclamation plant (WRP) and its recipient water body as a whole system, and assessed the ecological risk of the recipient water body caused by the WRP effluent. Instead of specific contaminants, two toxicity indicators, i.e. genotoxicity and estrogenicity, were selected to directly measure the biological effects of all bio-available contaminants in the reclaimed wastewater, as well as characterize the ecological risk of the recipient water. A series of physically based models were developed to simulate the toxicity indicators in a WRP through a typical reclamation process, including ultrafiltration, ozonation, and chlorination. After being validated against the field monitoring data from a full-scale WRP in Beijing, the models were applied to simulate the probability distribution of effluent toxicity of the WRP through Latin Hypercube Sampling to account for the variability of influent toxicity and operation conditions. The simulated effluent toxicity was then used to derive the predicted environmental concentration (PEC) in the recipient stream, considering the variations of the toxicity and flow of the upstream inflow as well. The ratio of the PEC of each toxicity indicator to its corresponding predicted no-effect concentration was finally used for the probabilistic ecological risk assessment. Regional sensitivity analysis was also performed with the developed models to identify the critical control variables and strategies for ecological risk management. PMID:27219046

  18. Probabilistic ecological risk assessment of effluent toxicity of a wastewater reclamation plant based on process modeling.

    PubMed

    Zeng, Siyu; Huang, Yunqing; Sun, Fu; Li, Dan; He, Miao

    2016-09-01

    The growing use of reclaimed wastewater for environmental purposes such as stream flow augmentation requires comprehensive ecological risk assessment and management. This study applied a system analysis approach, regarding a wastewater reclamation plant (WRP) and its recipient water body as a whole system, and assessed the ecological risk of the recipient water body caused by the WRP effluent. Instead of specific contaminants, two toxicity indicators, i.e. genotoxicity and estrogenicity, were selected to directly measure the biological effects of all bio-available contaminants in the reclaimed wastewater, as well as characterize the ecological risk of the recipient water. A series of physically based models were developed to simulate the toxicity indicators in a WRP through a typical reclamation process, including ultrafiltration, ozonation, and chlorination. After being validated against the field monitoring data from a full-scale WRP in Beijing, the models were applied to simulate the probability distribution of effluent toxicity of the WRP through Latin Hypercube Sampling to account for the variability of influent toxicity and operation conditions. The simulated effluent toxicity was then used to derive the predicted environmental concentration (PEC) in the recipient stream, considering the variations of the toxicity and flow of the upstream inflow as well. The ratio of the PEC of each toxicity indicator to its corresponding predicted no-effect concentration was finally used for the probabilistic ecological risk assessment. Regional sensitivity analysis was also performed with the developed models to identify the critical control variables and strategies for ecological risk management.

  19. Predicting aquatic toxicities of chemical pesticides in multiple test species using nonlinear QSTR modeling approaches.

    PubMed

    Basant, Nikita; Gupta, Shikha; Singh, Kunwar P

    2015-11-01

    In this study, we established nonlinear quantitative-structure toxicity relationship (QSTR) models for predicting the toxicities of chemical pesticides in multiple aquatic test species following the OECD (Organization for Economic Cooperation and Development) guidelines. The decision tree forest (DTF) and decision tree boost (DTB) based QSTR models were constructed using a pesticides toxicity dataset in Selenastrum capricornutum and a set of six descriptors. Other six toxicity data sets were used for external validation of the constructed QSTRs. Global QSTR models were also constructed using the combined dataset of all the seven species. The diversity in chemical structures and nonlinearity in the data were evaluated. Model validation was performed deriving several statistical coefficients for the test data and the prediction and generalization abilities of the QSTRs were evaluated. Both the QSTR models identified WPSA1 (weighted charged partial positive surface area) as the most influential descriptor. The DTF and DTB QSTRs performed relatively better than the single decision tree (SDT) and support vector machines (SVM) models used as a benchmark here and yielded R(2) of 0.886 and 0.964 between the measured and predicted toxicity values in the complete dataset (S. capricornutum). The QSTR models applied to six other aquatic species toxicity data yielded R(2) of >0.92 (DTF) and >0.97 (DTB), respectively. The prediction accuracies of the global models were comparable with those of the S. capricornutum models. The results suggest for the appropriateness of the developed QSTR models to reliably predict the aquatic toxicity of chemicals and can be used for regulatory purpose.

  20. Predicting aquatic toxicities of chemical pesticides in multiple test species using nonlinear QSTR modeling approaches.

    PubMed

    Basant, Nikita; Gupta, Shikha; Singh, Kunwar P

    2015-11-01

    In this study, we established nonlinear quantitative-structure toxicity relationship (QSTR) models for predicting the toxicities of chemical pesticides in multiple aquatic test species following the OECD (Organization for Economic Cooperation and Development) guidelines. The decision tree forest (DTF) and decision tree boost (DTB) based QSTR models were constructed using a pesticides toxicity dataset in Selenastrum capricornutum and a set of six descriptors. Other six toxicity data sets were used for external validation of the constructed QSTRs. Global QSTR models were also constructed using the combined dataset of all the seven species. The diversity in chemical structures and nonlinearity in the data were evaluated. Model validation was performed deriving several statistical coefficients for the test data and the prediction and generalization abilities of the QSTRs were evaluated. Both the QSTR models identified WPSA1 (weighted charged partial positive surface area) as the most influential descriptor. The DTF and DTB QSTRs performed relatively better than the single decision tree (SDT) and support vector machines (SVM) models used as a benchmark here and yielded R(2) of 0.886 and 0.964 between the measured and predicted toxicity values in the complete dataset (S. capricornutum). The QSTR models applied to six other aquatic species toxicity data yielded R(2) of >0.92 (DTF) and >0.97 (DTB), respectively. The prediction accuracies of the global models were comparable with those of the S. capricornutum models. The results suggest for the appropriateness of the developed QSTR models to reliably predict the aquatic toxicity of chemicals and can be used for regulatory purpose. PMID:26142614

  1. Somatic Growth Dilution of a toxicant in a predator-prey model under stoichiometric constraints.

    PubMed

    Peace, Angela; Poteat, Monica D; Wang, Hao

    2016-10-21

    The development of aquatic food chain models that incorporate both the effects of nutrient availability, as well as, track toxicants through trophic levels will shed light on ecotoxicological processes and ultimately help improve risk assessment efforts. Here we develop a stoichiometric aquatic food chain model of two trophic levels that investigates concurrent nutrient and toxic stressors in order to improve our understanding of the processes governing the trophic transfer for nutrients, energy, and toxicants. Analytical analysis of positive invariance, local stability of boundary equilibria, numerical simulations, and bifurcation analysis are presented. The model captures and explores a phenomenon called the Somatic Growth Dilution (SGD) effect recently observed empirically, where organisms experience a greater than proportional gain in biomass relative to toxicant concentrations when consuming food with high nutritional content vs. low quality food. PMID:27460586

  2. An amphibian model for studies of developmental reproductive toxicity.

    PubMed

    Berg, Cecilia

    2012-01-01

    The developmental programming of the reproductive system is vulnerable to chemical exposure. It is therefore important to evaluate long-term consequences of early life-stage exposure to endocrine disrupting chemicals. The African clawed frog Xenopus tropicalis has several characteristics which facilitates studies of developmental reproductive toxicity. Here, I present a X. tropicalis test protocol, including study design, exposure regime, and endpoints for chemical disruption of sex differentiation, reproductive organ development, the thyroxin-regulated metamorphosis, oestrogen synthesis (activity of the CYP19 aromatase enzyme), and fertility. PMID:22669660

  3. Economic damages of ozone air pollution to crops using combined air quality and GIS modelling

    NASA Astrophysics Data System (ADS)

    Vlachokostas, Ch.; Nastis, S. A.; Achillas, Ch.; Kalogeropoulos, K.; Karmiris, I.; Moussiopoulos, N.; Chourdakis, E.; Banias, G.; Limperi, N.

    2010-09-01

    This study aims at presenting a combined air quality and GIS modelling methodological approach in order to estimate crop damages from photochemical air pollution, depict their spatial resolution and assess the order of magnitude regarding the corresponding economic damages. The analysis is conducted within the Greater Thessaloniki Area, Greece, a Mediterranean territory which is characterised by high levels of photochemical air pollution and considerable agricultural activity. Ozone concentration fields for 2002 and for specific emission reduction scenarios for the year 2010 were estimated with the Ozone Fine Structure model in the area under consideration. Total economic damage to crops turns out to be significant and estimated to be approximately 43 M€ for the reference year. Production of cotton presents the highest economic loss, which is over 16 M€, followed by table tomato (9 M€), rice (4.2 M€), wheat (4 M€) and oilseed rape (2.8 M€) cultivations. Losses are not spread uniformly among farmers and the major losses occur in areas with valuable ozone-sensitive crops. The results are very useful for highlighting the magnitude of the total economic impacts of photochemical air pollution to the area's agricultural sector and can potentially be used for comparison with studies worldwide. Furthermore, spatial analysis of the economic damage could be of importance for governmental authorities and decision makers since it provides an indicative insight, especially if the economic instruments such as financial incentives or state subsidies to farmers are considered.

  4. Modelled air pollution levels versus EC air quality legislation - results from high resolution simulation.

    PubMed

    Chervenkov, Hristo

    2013-12-01

    An appropriate method for evaluating the air quality of a certain area is to contrast the actual air pollution levels to the critical ones, prescribed in the legislative standards. The application of numerical simulation models for assessing the real air quality status is allowed by the legislation of the European Community (EC). This approach is preferable, especially when the area of interest is relatively big and/or the network of measurement stations is sparse, and the available observational data are scarce, respectively. Such method is very efficient for similar assessment studies due to continuous spatio-temporal coverage of the obtained results. In the study the values of the concentration of the harmful substances sulphur dioxide, (SO2), nitrogen dioxide (NO2), particulate matter - coarse (PM10) and fine (PM2.5) fraction, ozone (O3), carbon monoxide (CO) and ammonia (NH3) in the surface layer obtained from modelling simulations with resolution 10 km on hourly bases are taken to calculate the necessary statistical quantities which are used for comparison with the corresponding critical levels, prescribed in the EC directives. For part of them (PM2.5, CO and NH3) this is done for first time with such resolution. The computational grid covers Bulgaria entirely and some surrounding territories and the calculations are made for every year in the period 1991-2000. The averaged over the whole time slice results can be treated as representative for the air quality situation of the last decade of the former century.

  5. Likelihood of achieving air quality targets under model uncertainties.

    PubMed

    Digar, Antara; Cohan, Daniel S; Cox, Dennis D; Kim, Byeong-Uk; Boylan, James W

    2011-01-01

    Regulatory attainment demonstrations in the United States typically apply a bright-line test to predict whether a control strategy is sufficient to attain an air quality standard. Photochemical models are the best tools available to project future pollutant levels and are a critical part of regulatory attainment demonstrations. However, because photochemical models are uncertain and future meteorology is unknowable, future pollutant levels cannot be predicted perfectly and attainment cannot be guaranteed. This paper introduces a computationally efficient methodology for estimating the likelihood that an emission control strategy will achieve an air quality objective in light of uncertainties in photochemical model input parameters (e.g., uncertain emission and reaction rates, deposition velocities, and boundary conditions). The method incorporates Monte Carlo simulations of a reduced form model representing pollutant-precursor response under parametric uncertainty to probabilistically predict the improvement in air quality due to emission control. The method is applied to recent 8-h ozone attainment modeling for Atlanta, Georgia, to assess the likelihood that additional controls would achieve fixed (well-defined) or flexible (due to meteorological variability and uncertain emission trends) targets of air pollution reduction. The results show that in certain instances ranking of the predicted effectiveness of control strategies may differ between probabilistic and deterministic analyses. PMID:21138291

  6. Likelihood of achieving air quality targets under model uncertainties.

    PubMed

    Digar, Antara; Cohan, Daniel S; Cox, Dennis D; Kim, Byeong-Uk; Boylan, James W

    2011-01-01

    Regulatory attainment demonstrations in the United States typically apply a bright-line test to predict whether a control strategy is sufficient to attain an air quality standard. Photochemical models are the best tools available to project future pollutant levels and are a critical part of regulatory attainment demonstrations. However, because photochemical models are uncertain and future meteorology is unknowable, future pollutant levels cannot be predicted perfectly and attainment cannot be guaranteed. This paper introduces a computationally efficient methodology for estimating the likelihood that an emission control strategy will achieve an air quality objective in light of uncertainties in photochemical model input parameters (e.g., uncertain emission and reaction rates, deposition velocities, and boundary conditions). The method incorporates Monte Carlo simulations of a reduced form model representing pollutant-precursor response under parametric uncertainty to probabilistically predict the improvement in air quality due to emission control. The method is applied to recent 8-h ozone attainment modeling for Atlanta, Georgia, to assess the likelihood that additional controls would achieve fixed (well-defined) or flexible (due to meteorological variability and uncertain emission trends) targets of air pollution reduction. The results show that in certain instances ranking of the predicted effectiveness of control strategies may differ between probabilistic and deterministic analyses.

  7. Simplified models to analyse time- and dose-dependent responses of populations to toxicants.

    PubMed

    Sánchez-Bayo, Francisco; Goka, Kouichi

    2007-10-01

    The basis of ecotoxicology lies currently in the dose-response of organisms to toxicants, as typically described by probit and logistic models. While recognising its merits, standard endpoints ignore the process of toxicity with time, and consequently our ability to predict direct toxic effects in environmental risk assessments is seriously curtailed. Although the response of toxicants with time has been studied before, its application in ecotoxicology remains underutilised. One reason is that no convincing mechanism has been proposed to explain the hyperbolic curves of such responses, whereas a variety of models have been used to describe them. The explanation of both time- and dose-dependent responses is found ultimately in the natural variability of receptor sites among individuals of populations exposed to a toxicant inhibitor with time. The process can be explained by the kinetics of inhibition, and is appropriately described by a simple mathematical expression like the Michaelis-Menten equation, though other asymptotic models (e.g. logistic model) can also be used. The advantage of the hyperbolic model is that median effect values (e.g. LC(50) for dose- and ET(50) for time-dependent responses) enable calculation of toxicity effects at any concentration level and/or time of exposure, thus making it especially attractive for risk assessment. PMID:17624612

  8. Toxicity of chlortetracycline and its metal complexes to model microorganisms in wastewater sludge.

    PubMed

    Pulicharla, Rama; Das, Ratul Kumar; Brar, Satinder Kaur; Drogui, Patrick; Sarma, Saurabh Jyoti; Verma, Mausam; Surampalli, Rao Y; Valero, Jose R

    2015-11-01

    Complexation of antibiotics with metals is a well-known phenomenon. Wastewater treatment plants contain metals and antibiotics, thus it is essential to know the effect of these complexes on toxicity towards microorganisms, typically present in secondary treatment processes. In this study, stability constants and toxicity of chlortetracycline (CTC) and metal (Ca, Mg, Cu and Cr) complexes were investigated. The calculated stability constants of CTC-metal complexes followed the order: Mg-CTC>Ca-CTC>Cu-CTC>Cr-CTC. Gram positive Bacillus thuringiensis (Bt) and Gram negative Enterobacter aerogenes (Ea) bacteria were used as model microorganisms to evaluate the toxicity of CTC and its metal complexes. CTC-metal complexes were more toxic than the CTC itself for Bt whereas for Ea, CTC and its metal complexes showed similar toxicity. In contrast, CTC spiked wastewater sludge (WWS) did not show any toxic effect compared to synthetic sewage. This study provides evidence that CTC and its metal complexes are toxic to bacteria when they are biologically available. As for WWS, CTC was adsorbed to solid part and was not biologically available to show measurable toxic effects.

  9. Toxicity of chlortetracycline and its metal complexes to model microorganisms in wastewater sludge.

    PubMed

    Pulicharla, Rama; Das, Ratul Kumar; Brar, Satinder Kaur; Drogui, Patrick; Sarma, Saurabh Jyoti; Verma, Mausam; Surampalli, Rao Y; Valero, Jose R

    2015-11-01

    Complexation of antibiotics with metals is a well-known phenomenon. Wastewater treatment plants contain metals and antibiotics, thus it is essential to know the effect of these complexes on toxicity towards microorganisms, typically present in secondary treatment processes. In this study, stability constants and toxicity of chlortetracycline (CTC) and metal (Ca, Mg, Cu and Cr) complexes were investigated. The calculated stability constants of CTC-metal complexes followed the order: Mg-CTC>Ca-CTC>Cu-CTC>Cr-CTC. Gram positive Bacillus thuringiensis (Bt) and Gram negative Enterobacter aerogenes (Ea) bacteria were used as model microorganisms to evaluate the toxicity of CTC and its metal complexes. CTC-metal complexes were more toxic than the CTC itself for Bt whereas for Ea, CTC and its metal complexes showed similar toxicity. In contrast, CTC spiked wastewater sludge (WWS) did not show any toxic effect compared to synthetic sewage. This study provides evidence that CTC and its metal complexes are toxic to bacteria when they are biologically available. As for WWS, CTC was adsorbed to solid part and was not biologically available to show measurable toxic effects. PMID:26119381

  10. QSAR models for predicting in vivo aquatic toxicity of chlorinated alkanes to fish.

    PubMed

    Zvinavashe, Elton; van den Berg, Hans; Soffers, Ans E M F; Vervoort, Jacques; Freidig, Andreas; Murk, Albertinka J; Rietjens, Ivonne M C M

    2008-03-01

    Quantitative structure-activity relationship (QSAR) models are expected to play a crucial role in reducing the number of animals to be used for toxicity testing resulting from the adoption of the new European Union chemical control system called Registration, Evaluation, and Authorization of Chemicals (REACH). The objective of the present study was to generate in vitro acute toxicity data that could be used to develop a QSAR model to describe acute in vivo toxicity of chlorinated alkanes. Cytotoxicity of a series of chlorinated alkanes to Chinese hamster ovary (CHO) cells was observed at concentrations similar to those that have been shown previously to be toxic to fish. Strong correlations exist between the acute in vitro toxicity of the chlorinated alkanes and (i) hydrophobicity [modeled by the calculated log K ow (octanol-water partition coefficient); r (2) = 0.883 and r int (2) = 0.854] and (ii) in vivo acute toxicity to fish ( r (2) = 0.758). A QSAR model has been developed to predict in vivo acute toxicity to fish, based on the in vitro data and even on in silico log K ow data only. The developed QSAR model is applicable to chlorinated alkanes with up to 10 carbon atoms, up to eight chlorine atoms, and log K ow values lying within the range from 1.71 to 5.70. Out of the 100204 compounds on the European Inventory of Existing Chemicals (EINECS), our QSAR model covers 77 (0.1%) of them. Our findings demonstrate that in vitro experiments and even in silico calculations can replace animal experiments in the prediction of the acute toxicity of chlorinated alkanes.

  11. Meteorological Processes Affecting Air Quality – Research and Model Development Needs

    EPA Science Inventory

    Meteorology modeling is an important component of air quality modeling systems that defines the physical and dynamical environment for atmospheric chemistry. The meteorology models used for air quality applications are based on numerical weather prediction models that were devel...

  12. European Air Quality and Climate Change: a numerical modeling study

    NASA Astrophysics Data System (ADS)

    Lacressonniere, G.

    2011-12-01

    In the context of climate change, the evolution of air quality in Europe is a challenging scientific question, despite the political measures taken to limit and reduce anthropogenic emissions. Heat waves, changes in transport pathways or synoptic patterns, increase of emissions in other areas in the world, or for instance possible increase of biogenic emissions or changes in deposition and land use may affect adversely future Air Quality levels in Europe. In the context of a project co-funded by the French environment agency ADEME, a numerical modeling study has begun relying on the tools used by Météo-France for its contribution to the 5th IPCC assessment report, to GMES atmospheric services (MACC FP7 project) and to the French national operational Air Quality platform Prév'Air (http://www.prevair.org). In particular, the MOCAGE 3-D chemical transport model (CTM) is used with a configuration comprising a global (2°) and a European domain (0.2°), allowing representation of both long-range transport of pollutants and European Air Quality at relevant resolutions and with a two-ways coupling. MOCAGE includes 47 layers from the surface to 5hPa. The first step of this project was to assess the impact of meteorological forcings, either analyses ("best" meteorology available for the recent past) or climate runs for the current atmosphere, on air quality hindcasts with MOCAGE over Europe. For these climate runs, we rely on Météo-France Earth-System model CNRM-CM, and particularly the ARPEGE-climate general circulation model for the atmosphere. By studying several key variables for Air Quality (surface and low troposphere concentrations of ozone, nitrogen oxides, volatile organic compounds, radicals, PM,...), we investigated the indicators that are robust, through averages over several years, (monthly averages, frequency of exceedances, AOTs, ...) for a given climate when using climatological forcings instead of analyses, which constitutes the reference. Both

  13. Air Dispersion Modeling for the INL Application for a Synthetic Minor Sitewide Air Quality Permit to Construct with a Facility Emission Cap Component

    SciTech Connect

    Sondrup, Andrus Jeffrey

    2015-10-01

    The Department of Energy Idaho Operations Office (DOE-ID) is applying for a synthetic minor, Sitewide, air quality permit to construct (PTC) with a facility emission cap (FEC) component from the Idaho Department of Environmental Quality (DEQ) for Idaho National Laboratory (INL) to limit its potential to emit to less than major facility limits for criteria air pollutants (CAPs) and hazardous air pollutants (HAPs) regulated under the Clean Air Act. This document is supplied as an appendix to the application, Idaho National Laboratory Application for a Synthetic Minor Sitewide Air Quality Permit to Construct with a Facility Emissions Cap Component, hereafter referred to as “permit application” (DOE-ID 2015). Air dispersion modeling was performed as part of the permit application process to demonstrate pollutant emissions from the INL will not cause a violation of any ambient air quality standards. This report documents the modeling methodology and results for the air dispersion impact analysis. All CAPs regulated under Section 109 of the Clean Air Act were modeled with the exception of lead (Pb) and ozone, which are not required to be modeled by DEQ. Modeling was not performed for toxic air pollutants (TAPs) as uncontrolled emissions did not exceed screening emission levels for carcinogenic and non-carcinogenic TAPs. Modeling for CAPs was performed with the EPA approved AERMOD dispersion modeling system (Version 14134) (EPA 2004a) and five years (2000-2004) of meteorological data. The meteorological data set was produced with the companion AERMET model (Version 14134) (EPA 2004b) using surface data from the Idaho Falls airport, and upper-air data from Boise International Airport supplied by DEQ. Onsite meteorological data from the Grid 3 Mesonet tower located near the center of the INL (north of INTEC) and supplied by the local National Oceanic and Atmospheric Administration (NOAA) office was used for surface wind directions and wind speeds. Surface data (i

  14. A Bayesian network model for predicting aquatic toxicity mode of action using two dimensional theoretical molecular descriptors

    EPA Science Inventory

    The mode of toxic action (MoA) has been recognized as a key determinant of chemical toxicity, but development of predictive MoA classification models in aquatic toxicology has been limited. We developed a Bayesian network model to classify aquatic toxicity MoA using a recently pu...

  15. MOAtox: A comprehensive mode of action and acute aquatic toxicity database for predictive model development (SETAC abstract)

    EPA Science Inventory

    The mode of toxic action (MOA) has been recognized as a key determinant of chemical toxicity and as an alternative to chemical class-based predictive toxicity modeling. However, the development of quantitative structure activity relationship (QSAR) and other models has been limit...

  16. Xenotransplantation Models to Study the Effects of Toxicants on Human Fetal Tissues1

    PubMed Central

    Spade, Daniel J.; McDonnell, Elizabeth V.; Heger, Nicholas E.; Sanders, Jennifer A.; Saffarini, Camelia M.; Gruppuso, Philip A.; De Paepe, Monique E.; Boekelheide, Kim

    2015-01-01

    Many diseases that manifest throughout the lifetime are influenced by factors affecting fetal development. Fetal exposure to xenobiotics, in particular, may influence the development of adult diseases. Established animal models provide systems for characterizing both developmental biology and developmental toxicology. However, animal model systems do not allow researchers to assess the mechanistic effects of toxicants on developing human tissue. Human fetal tissue xenotransplantation models have recently been implemented to provide human-relevant mechanistic data on the many tissue-level functions that may be affected by fetal exposure to toxicants. This review describes the development of human fetal tissue xenotransplant models for testis, prostate, lung, liver, and adipose tissue, aimed at studying the effects of xenobiotics on tissue development, including implications for testicular dysgenesis, prostate disease, lung disease, and metabolic syndrome. The mechanistic data obtained from these models can complement data from epidemiology, traditional animal models, and in vitro studies to quantify the risks of toxicant exposures during human development. PMID:25477288

  17. Gene expression patterns in Rainbow Trout, Oncorhynchus mykiss, exposed to a suite of model toxicants

    SciTech Connect

    Hook, Sharon E.; Skillman, Ann D.; Small, Jonathan A.; Schultz, Irv R.

    2006-05-25

    The increased availability and use of DNA microarrays has allowed the characterization of gene expression patterns associated with different toxicants. An important question is whether toxicant induced changes in gene expression in fish are sufficiently diverse to allow for identification of specific modes of action and/or specific contaminants. In theory, each class of toxicant may generate a gene expression profile unique to its mode of toxic action. We exposed isogenic (cloned) rainbow trout Oncorhyncus mykiss, to sublethal levels of a series of model toxicants with varying modes of action, including ethynylestradiol (xeno-estrogen), trenbolone (anabolic steroid; model androgen), 2,2,4,4´tetrabromodiphenyl ether (BDE-47, thyroid active), diquat (oxidant stressor), chromium VI, and benzo[a]pyrene (BaP) for a period of 1-3 weeks. Following exposure, fish were euthanized, livers harvested and RNA extracted. Fluorescently labeled cDNA were generated and hybridized against a commercially available Atlantic Salmon / Trout array (GRASP project, University of Victoria) spotted with 16,000 cDNA’s. The slides were scanned to measure abundance of a given transcript in each sample relative to controls. Data were analyzed via Genespring (Silicon Genetics) to identify a list of up and down regulated genes, as well as to determine gene clustering patterns that can be used as “expression signatures”. Our analysis indicates each toxicant generated specific gene expression profiles. Most genes exhibiting altered expression responded to only one of the toxicants. Relatively few genes are co-expressed in multiple treatments. For example, BaP and Diquat, both of which exert toxicity via oxidative stress, up-regulated 28 of the same genes, of over 100 genes altered by ether treatment. Other genes associated with steroidogenesis, p450 and estrogen responsive genes appear to be useful for selectively identifying toxicant mode of in fish, suggesting a link between gene expression

  18. Modeling, Monitoring and Fault Diagnosis of Spacecraft Air Contaminants

    NASA Technical Reports Server (NTRS)

    Ramirez, W. Fred; Skliar, Mikhail; Narayan, Anand; Morgenthaler, George W.; Smith, Gerald J.

    1998-01-01

    Control of air contaminants is a crucial factor in the safety considerations of crewed space flight. Indoor air quality needs to be closely monitored during long range missions such as a Mars mission, and also on large complex space structures such as the International Space Station. This work mainly pertains to the detection and simulation of air contaminants in the space station, though much of the work is easily extended to buildings, and issues of ventilation systems. Here we propose a method with which to track the presence of contaminants using an accurate physical model, and also develop a robust procedure that would raise alarms when certain tolerance levels are exceeded. A part of this research concerns the modeling of air flow inside a spacecraft, and the consequent dispersal pattern of contaminants. Our objective is to also monitor the contaminants on-line, so we develop a state estimation procedure that makes use of the measurements from a sensor system and determines an optimal estimate of the contamination in the system as a function of time and space. The real-time optimal estimates in turn are used to detect faults in the system and also offer diagnoses as to their sources. This work is concerned with the monitoring of air contaminants aboard future generation spacecraft and seeks to satisfy NASA's requirements as outlined in their Strategic Plan document (Technology Development Requirements, 1996).

  19. Modeling Airborne Beryllium Concentrations From Open Air Dynamic Testing

    NASA Astrophysics Data System (ADS)

    Becker, N. M.

    2003-12-01

    A heightened awareness of airborne beryllium contamination from industrial activities was reestablished during the late 1980's and early 1990's when it became recognized that Chronic Beryllium Disease (CBD) had not been eradicated, and that the Occupational Health and Safety Administration standards for occupational air exposure to beryllium may not be sufficiently protective. This was in response to the observed CBD increase in multiple industrial settings where beryllium was manufactured and/or machined, thus producing beryllium particulates which are then available for redistribution by airborne transport. Sampling and modeling design activities were expanded at Los Alamos National Laboratory in New Mexico to evaluate potential airborne beryllium exposure to workers who might be exposed during dynamic testing activities associated with nuclear weapons Stockpile Stewardship. Herein is presented the results of multiple types of collected air measurements that were designed to characterize the production and dispersion of beryllium used in components whose performance is evaluated during high explosive detonation at open air firing sites. Data from fallout, high volume air, medium volume air, adhesive film, particle size impactor, and fine-particulate counting techniques will be presented, integrated, and applied in dispersion modeling to assess potential onsite and offsite personal exposures resulting from dynamic testing activities involving beryllium.

  20. Modeling VOC emissions and air concentrations from the Exxon Valdez oil spill

    SciTech Connect

    Hanna, S.R. ); Drivas, P.J. )

    1993-03-01

    During the two-week period following the Exxon Valdez oil spill in March 1989 in Prince William Sound, Alaska, toxic volatile organic compounds (VOCs) evaporated from the surface of the oil spill and were transported and dispersed throughout the region. To estimate the air concentrations of these VOCs, emissions and dispersion modeling was conducted for each hour during the first two weeks of the spill. A multicomponent evaporative emissions model was developed and applied to the oil spill; the model considered the evaporation of 15 specific compounds, including benzene and toluene. Both mass transfer from the surface of the spill and diffusion through the oil layer were considered in the emissions model. Maximum emissions of toluene were calculated to equal about 20,000 kg/hr, or about 5 g/m[sup 2] hr, at a time of eight hours after the initial oil spill. Meteorological data were acquired from sources and used to estimate hourly-averaged wind velocity over the spill. Air concentrations of specific components were calculated using the ATDL area source diffusion model and the Offshore and Coastal Dispersion (OCD) model. Maximum hourly-averaged concentrations were predicted not to exceed 10 ppmv for any compound. 24 refs., 6 figs., 4 tabs.

  1. Validation of a 3-D hemispheric nested air pollution model

    NASA Astrophysics Data System (ADS)

    Frohn, L. M.; Christensen, J. H.; Brandt, J.; Geels, C.; Hansen, K. M.

    2003-07-01

    Several air pollution transport models have been developed at the National Environmental Research Institute in Denmark over the last decade (DREAM, DEHM, ACDEP and DEOM). A new 3-D nested Eulerian transport-chemistry model: REGIonal high resolutioN Air pollution model (REGINA) is based on modules and parameterisations from these models as well as new methods. The model covers the majority of the Northern Hemisphere with currently one nest implemented. The horizontal resolution in the mother domain is 150 km × 150 km, and the nesting factor is three. A chemical scheme (originally 51 species) has been extended with a detailed description of the ammonia chemistry and implemented in the model. The mesoscale numerical weather prediction model MM5v2 is used as meteorological driver for the model. The concentrations of air pollutants, such as sulphur and nitrogen in various forms, have been calculated, applying zero nesting and one nest. The model setup is currently being validated by comparing calculated values of concentrations to measurements from approximately 100 stations included in the European Monitoring and Evalutation Programme (EMEP). The present paper describes the physical processes and parameterisations of the model together with the modifications of the chemical scheme. Validation of the model calculations by comparison to EMEP measurements for a summer and a winter month is shown and discussed. Furthermore, results from a sensitivity study of the model performance with respect to resolution in emission and meteorology input data is presented. Finally the future prospects of the model are discussed. The overall validation shows that the model performs well with respect to correlation for both monthly and daily mean values.

  2. Scale Issues in Air Quality Modeling Policy Support

    EPA Science Inventory

    This study examines the issues relating to the use of regional photochemical air quality models for evaluating their performance in reproducing the spatio-temporal features embedded in the observations and for designing emission control strategies needed to achieve compliance wit...

  3. AQMEII: A New International Initiative on Air Quality Model Evaluation

    EPA Science Inventory

    We provide a conceptual view of the process of evaluating regional-scale three-dimensional numerical photochemical air quality modeling system, based on an examination of existing approached to the evaluation of such systems as they are currently used in a variety of application....

  4. Using biodynamic models to reconcile differences between laboratory toxicity tests and field biomonitoring with aquatic insects

    USGS Publications Warehouse

    Buchwalter, D.B.; Cain, D.J.; Clements, W.H.; Luoma, S.N.

    2007-01-01

    Aquatic insects often dominate lotic ecosystems, yet these organisms are under-represented in trace metal toxicity databases. Furthermore, toxicity data for aquatic insects do not appear to reflect their actual sensitivities to metals in nature, because the concentrations required to elicit toxicity in the laboratory are considerably higher than those found to impact insect communities in the field. New approaches are therefore needed to better understand how and why insects are differentially susceptible to metal exposures. Biodynamic modeling is a powerful tool for understanding interspecific differences in trace metal bioaccumulation. Because bioaccumulation alone does not necessarily correlate with toxicity, we combined biokinetic parameters associated with dissolved cadmium exposures with studies of the subcellular compartmentalization of accumulated Cd. This combination of physiological traits allowed us to make predictions of susceptibility differences to dissolved Cd in three aquatic insect taxa: Ephemerella excrucians, Rhithrogena morrisoni, and Rhyacophila sp. We compared these predictions with long-term field monitoring data and toxicity tests with closely related taxa: Ephemerella infrequens, Rhithrogena hageni, and Rhyacophila brunea. Kinetic parameters allowed us to estimate steady-state concentrations, the time required to reach steady state, and the concentrations of Cd projected to be in potentially toxic compartments for different species. Species-specific physiological traits identified using biodynamic models provided a means for better understanding why toxicity assays with insects have failed to provide meaningful estimates for metal concentrations that would be expected to be protective in nature. ?? 2007 American Chemical Society.

  5. The analysis of a generic air-to-air missile simulation model

    NASA Technical Reports Server (NTRS)

    Kaplan, Joseph A.; Chappell, Alan R.; Mcmanus, John W.

    1994-01-01

    A generic missile model was developed to evaluate the benefits of using a dynamic missile fly-out simulation system versus a static missile launch envelope system for air-to-air combat simulation. This paper examines the performance of a launch envelope model and a missile fly-out model. The launch envelope model bases its probability of killing the target aircraft on the target aircraft's position at the launch time of the weapon. The benefits gained from a launch envelope model are the simplicity of implementation and the minimal computational overhead required. A missile fly-out model takes into account the physical characteristics of the missile as it simulates the guidance, propulsion, and movement of the missile. The missile's probability of kill is based on the missile miss distance (or the minimum distance between the missile and the target aircraft). The problems associated with this method of modeling are a larger computational overhead, the additional complexity required to determine the missile miss distance, and the additional complexity of determining the reason(s) the missile missed the target. This paper evaluates the two methods and compares the results of running each method on a comprehensive set of test conditions.

  6. InMAP: a new model for air pollution interventions

    NASA Astrophysics Data System (ADS)

    Tessum, C. W.; Hill, J. D.; Marshall, J. D.

    2015-10-01

    Mechanistic air pollution models are essential tools in air quality management. Widespread use of such models is hindered, however, by the extensive expertise or computational resources needed to run most models. Here, we present InMAP (Intervention Model for Air Pollution), which offers an alternative to comprehensive air quality models for estimating the air pollution health impacts of emission reductions and other potential interventions. InMAP estimates annual-average changes in primary and secondary fine particle (PM2.5) concentrations - the air pollution outcome generally causing the largest monetized health damages - attributable to annual changes in precursor emissions. InMAP leverages pre-processed physical and chemical information from the output of a state-of-the-science chemical transport model (WRF-Chem) within an Eulerian modeling framework, to perform simulations that are several orders of magnitude less computationally intensive than comprehensive model simulations. InMAP uses a variable resolution grid that focuses on human exposures by employing higher spatial resolution in urban areas and lower spatial resolution in rural and remote locations and in the upper atmosphere; and by directly calculating steady-state, annual average concentrations. In comparisons run here, InMAP recreates WRF-Chem predictions of changes in total PM2.5 concentrations with population-weighted mean fractional error (MFE) and bias (MFB) < 10 % and population-weighted R2 ~ 0.99. Among individual PM2.5 species, the best predictive performance is for primary PM2.5 (MFE: 16 %; MFB: 13 %) and the worst predictive performance is for particulate nitrate (MFE: 119 %; MFB: 106 %). Potential uses of InMAP include studying exposure, health, and environmental justice impacts of potential shifts in emissions for annual-average PM2.5. Features planned for future model releases include a larger spatial domain, more temporal information, and the ability to predict ground-level ozone (O3

  7. QSAR models for reproductive toxicity and endocrine disruption in regulatory use – a preliminary investigation†

    PubMed Central

    Jensen, G.E.; Niemelä, J.R.; Wedebye, E.B.; Nikolov, N.G.

    2008-01-01

    A special challenge in the new European Union chemicals legislation, Registration, Evaluation and Authorisation of Chemicals, will be the toxicological evaluation of chemicals for reproductive toxicity. Use of valid quantitative structure–activity relationships (QSARs) is a possibility under the new legislation. This article focuses on a screening exercise by use of our own and commercial QSAR models for identification of possible reproductive toxicants. Three QSAR models were used for reproductive toxicity for the endpoints teratogenic risk to humans (based on animal tests, clinical data and epidemiological human studies), dominant lethal effect in rodents (in vivo) and Drosophila melanogaster sex-linked recessive lethal effect. A structure set of 57,014 European Inventory of Existing Chemical Substances (EINECS) chemicals was screened. A total of 5240 EINECS chemicals, corresponding to 9.2%, were predicted as reproductive toxicants by one or more of the models. The chemicals predicted positive for reproductive toxicity will be submitted to the Danish Environmental Protection Agency as scientific input for a future updated advisory classification list with advisory classifications for concern for humans owing to possible developmental toxic effects: Xn (Harmful) and R63 (Possible risk of harm to the unborn child). The chemicals were also screened in three models for endocrine disruption. PMID:19061080

  8. Prediction of organ toxicity endpoints by QSAR modeling based on precise chemical-histopathology annotations.

    PubMed

    Myshkin, Eugene; Brennan, Richard; Khasanova, Tatiana; Sitnik, Tatiana; Serebriyskaya, Tatiana; Litvinova, Elena; Guryanov, Alexey; Nikolsky, Yuri; Nikolskaya, Tatiana; Bureeva, Svetlana

    2012-09-01

    The ability to accurately predict the toxicity of drug candidates from their chemical structure is critical for guiding experimental drug discovery toward safer medicines. Under the guidance of the MetaTox consortium (Thomson Reuters, CA, USA), which comprised toxicologists from the pharmaceutical industry and government agencies, we created a comprehensive ontology of toxic pathologies for 19 organs, classifying pathology terms by pathology type and functional organ substructure. By manual annotation of full-text research articles, the ontology was populated with chemical compounds causing specific histopathologies. Annotated compound-toxicity associations defined histologically from rat and mouse experiments were used to build quantitative structure-activity relationship models predicting subcategories of liver and kidney toxicity: liver necrosis, liver relative weight gain, liver lipid accumulation, nephron injury, kidney relative weight gain, and kidney necrosis. All models were validated using two independent test sets and demonstrated overall good performance: initial validation showed 0.80-0.96 sensitivity (correctly predicted toxic compounds) and 0.85-1.00 specificity (correctly predicted non-toxic compounds). Later validation against a test set of compounds newly added to the database in the 2 years following initial model generation showed 75-87% sensitivity and 60-78% specificity. General hepatotoxicity and nephrotoxicity models were less accurate, as expected for more complex endpoints.

  9. Modeling air pollution in the Tracking and Analysis Framework (TAF)

    SciTech Connect

    Shannon, J.D.

    1998-12-31

    The Tracking and Analysis Framework (TAF) is a set of interactive computer models for integrated assessment of the Acid Rain Provisions (Title IV) of the 1990 Clean Air Act Amendments. TAF is designed to execute in minutes on a personal computer, thereby making it feasible for a researcher or policy analyst to examine quickly the effects of alternate modeling assumptions or policy scenarios. Because the development of TAF involves researchers in many different disciplines, TAF has been given a modular structure. In most cases, the modules contain reduced-form models that are based on more complete models exercised off-line. The structure of TAF as of December 1996 is shown. Both the Atmospheric Pathways Module produce estimates for regional air pollution variables.

  10. Dynamic energy-based modeling of uranium and cadmium joint toxicity to Caenorhabditis elegans.

    PubMed

    Margerit, Adrien; Gomez, Elena; Gilbin, Rodolphe

    2016-03-01

    Toxicokinetic - toxicodynamic energy-based models offer new alternatives to the commonly used approaches for the analysis of mixture toxicity data. Based on the Dynamic Energy Budget theory, DEBtox models enable the description of several endpoints over time simultaneously under the same framework. However, such model still has to be faced with experimental data in a multi-contamination context. In this study, the predictive capacities of a DEBtox model to describe the uranium and cadmium joint toxicity over the entire growth and reproduction period of the soil nematode Caenorhabditis elegans was examined. The two reference additivity approaches, Concentration Addition and Response addition, implemented in the DEBtox model were tested. Assuming no interaction between the two toxicants through Response addition, the DEBtox model allowed a rather accurate fit of the U and Cd joint effects on the growth and reproduction of C. elegans: an interaction between the two metals at the toxicokinetic or toxicodynamic level seems thus unlikely or has only minor consequences. Interestingly, this study underlines that even if the compounds of a mixture share the same DEBtox physiological mode of action (in this case a decrease in assimilation), the Response addition approach may provide a better fit of joint toxicity data than the Concentration addition approach. Moreover, the present work highlighted limitations in the model predictions which are related to the simplifications of the DEBtox framework and its adaptations to the physiology of C. elegans and which lead to an overestimation of the U and Cd joint toxicity in some cases.

  11. Air pollution dispersion models for human exposure predictions in London.

    PubMed

    Beevers, Sean D; Kitwiroon, Nutthida; Williams, Martin L; Kelly, Frank J; Ross Anderson, H; Carslaw, David C

    2013-01-01

    The London household survey has shown that people travel and are exposed to air pollutants differently. This argues for human exposure to be based upon space-time-activity data and spatio-temporal air quality predictions. For the latter, we have demonstrated the role that dispersion models can play by using two complimentary models, KCLurban, which gives source apportionment information, and Community Multi-scale Air Quality Model (CMAQ)-urban, which predicts hourly air quality. The KCLurban model is in close agreement with observations of NO(X), NO(2) and particulate matter (PM)(10/2.5), having a small normalised mean bias (-6% to 4%) and a large Index of Agreement (0.71-0.88). The temporal trends of NO(X) from the CMAQ-urban model are also in reasonable agreement with observations. Spatially, NO(2) predictions show that within 10's of metres of major roads, concentrations can range from approximately 10-20 p.p.b. up to 70 p.p.b. and that for PM(10/2.5) central London roadside concentrations are approximately double the suburban background concentrations. Exposure to different PM sources is important and we predict that brake wear-related PM(10) concentrations are approximately eight times greater near major roads than at suburban background locations. Temporally, we have shown that average NO(X) concentrations close to roads can range by a factor of approximately six between the early morning minimum and morning rush hour maximum periods. These results present strong arguments for the hybrid exposure model under development at King's and, in future, for in-building models and a model for the London Underground.

  12. Modeling of air pollution from the power plant ash dumps

    NASA Astrophysics Data System (ADS)

    Aleksic, Nenad M.; Balać, Nedeljko

    A simple model of air pollution from power plant ash dumps is presented, with emission rates calculated from the Bagnold formula and transport simulated by the ATDL type model. Moisture effects are accounted for by assumption that there is no pollution on rain days. Annual mean daily sedimentation rates, calculated for the area around the 'Nikola Tesla' power plants near Belgrade for 1987, show reasonably good agreement with observations.

  13. Air-water analogy and the study of hydraulic models

    NASA Technical Reports Server (NTRS)

    Supino, Giulio

    1953-01-01

    The author first sets forth some observations about the theory of models. Then he established certain general criteria for the construction of dynamically similar models in water and in air, through reference to the perfect fluid equations and to the ones pertaining to viscous flow. It is, in addition, pointed out that there are more cases in which the analogy is possible than is commonly supposed.

  14. Per- and polyfluoro toxicity (LC(50) inhalation) study in rat and mouse using QSAR modeling.

    PubMed

    Bhhatarai, Barun; Gramatica, Paola

    2010-03-15

    Fully or partially fluorinated compounds, known as per- and polyfluorinated chemicals are widely distributed in the environment and released because of their use in different household and industrial products. Few of these long chain per- and polyfluorinated chemicals are classified as emerging pollutants, and their environmental and toxicological effects are unveiled in the literature. This has diverted the production of long chain compounds, considered as more toxic, to short chains, but concerns regarding the toxicity of both types of per- and polyfluorinated chemicals are alarming. There are few experimental data available on the environmental behavior and toxicity of these compounds, and moreover, toxicity profiles are found to be different for the types of animals and species used. Quantitative structure-activity relationship (QSAR) is applied to a combination of short and long chain per- and polyfluorinated chemicals, for the first time, to model and predict the toxicity on two species of rodents, rat (Rattus) and mouse (Mus), by modeling inhalation (LC(50)) data. Multiple linear regression (MLR) models using the ordinary-least-squares (OLS) method, based on theoretical molecular descriptors selected by genetic algorithm (GA), were used for QSAR studies. Training and prediction sets were prepared a priori, and these sets were used to derive statistically robust and predictive (both internally and externally) models. The structural applicability domain (AD) of the model was verified on a larger set of per- and polyfluorinated chemicals retrieved from different databases and journals. The descriptors involved, the similarities, and the differences observed between models pertaining to the toxicity related to the two species are discussed. Chemometric methods such as principal component analysis (PCA) and multidimensional scaling (MDS) were used to select most toxic compounds from those within the AD of both models, which will be subjected to experimental tests

  15. 40 CFR Table 4 to Subpart Dddd of... - Model Rule-Toxic Equivalency Factors

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Table 4 to Subpart DDDD of Part 60—Model Rule—Toxic Equivalency Factors Dioxin/furan isomer Toxic equivalency factor 2,3,7,8-tetrachlorinated dibenzo-p-dioxin 1 1,2,3,7,8-pentachlorinated dibenzo-p-dioxin 0.5 1,2,3,4,7,8-hexachlorinated dibenzo-p-dioxin 0.1 1,2,3,7,8,9-hexachlorinated dibenzo-p-dioxin 0.1...

  16. 40 CFR Table 4 to Subpart Dddd of... - Model Rule-Toxic Equivalency Factors

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Table 4 to Subpart DDDD of Part 60—Model Rule—Toxic Equivalency Factors Dioxin/furan congener Toxic equivalency factor 2,3,7,8-tetrachlorinated dibenzo-p-dioxin 1 1,2,3,7,8-pentachlorinated dibenzo-p-dioxin 0.5 1,2,3,4,7,8-hexachlorinated dibenzo-p-dioxin 0.1 1,2,3,7,8,9-hexachlorinated dibenzo-p-dioxin 0.1...

  17. 40 CFR Table 4 to Subpart Dddd of... - Model Rule-Toxic Equivalency Factors

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Table 4 to Subpart DDDD of Part 60—Model Rule—Toxic Equivalency Factors Dioxin/furan isomer Toxic equivalency factor 2,3,7,8-tetrachlorinated dibenzo-p-dioxin 1 1,2,3,7,8-pentachlorinated dibenzo-p-dioxin 0.5 1,2,3,4,7,8-hexachlorinated dibenzo-p-dioxin 0.1 1,2,3,7,8,9-hexachlorinated dibenzo-p-dioxin 0.1...

  18. Multispecies QSAR modeling for predicting the aquatic toxicity of diverse organic chemicals for regulatory toxicology.

    PubMed

    Singh, Kunwar P; Gupta, Shikha; Kumar, Anuj; Mohan, Dinesh

    2014-05-19

    The research aims to develop multispecies quantitative structure-activity relationships (QSARs) modeling tools capable of predicting the acute toxicity of diverse chemicals in various Organization for Economic Co-operation and Development (OECD) recommended test species of different trophic levels for regulatory toxicology. Accordingly, the ensemble learning (EL) approach based classification and regression QSAR models, such as decision treeboost (DTB) and decision tree forest (DTF) implementing stochastic gradient boosting and bagging algorithms were developed using the algae (P. subcapitata) experimental toxicity data for chemicals. The EL-QSAR models were successfully applied to predict toxicities of wide groups of chemicals in other test species including algae (S. obliguue), daphnia, fish, and bacteria. Structural diversity of the selected chemicals and those of the end-point toxicity data of five different test species were tested using the Tanimoto similarity index and Kruskal-Wallis (K-W) statistics. Predictive and generalization abilities of the constructed QSAR models were compared using statistical parameters. The developed QSAR models (DTB and DTF) yielded a considerably high classification accuracy in complete data of model building (algae) species (97.82%, 99.01%) and ranged between 92.50%-94.26% and 92.14%-94.12% in four test species, respectively, whereas regression QSAR models (DTB and DTF) rendered high correlation (R(2)) between the measured and model predicted toxicity end-point values and low mean-squared error in model building (algae) species (0.918, 0.15; 0.905, 0.21) and ranged between 0.575 and 0.672, 0.18-0.51 and 0.605-0.689 and 0.20-0.45 in four different test species. The developed QSAR models exhibited good predictive and generalization abilities in different test species of varied trophic levels and can be used for predicting the toxicities of new chemicals for screening and prioritization of chemicals for regulation.

  19. Multispecies QSAR modeling for predicting the aquatic toxicity of diverse organic chemicals for regulatory toxicology.

    PubMed

    Singh, Kunwar P; Gupta, Shikha; Kumar, Anuj; Mohan, Dinesh

    2014-05-19

    The research aims to develop multispecies quantitative structure-activity relationships (QSARs) modeling tools capable of predicting the acute toxicity of diverse chemicals in various Organization for Economic Co-operation and Development (OECD) recommended test species of different trophic levels for regulatory toxicology. Accordingly, the ensemble learning (EL) approach based classification and regression QSAR models, such as decision treeboost (DTB) and decision tree forest (DTF) implementing stochastic gradient boosting and bagging algorithms were developed using the algae (P. subcapitata) experimental toxicity data for chemicals. The EL-QSAR models were successfully applied to predict toxicities of wide groups of chemicals in other test species including algae (S. obliguue), daphnia, fish, and bacteria. Structural diversity of the selected chemicals and those of the end-point toxicity data of five different test species were tested using the Tanimoto similarity index and Kruskal-Wallis (K-W) statistics. Predictive and generalization abilities of the constructed QSAR models were compared using statistical parameters. The developed QSAR models (DTB and DTF) yielded a considerably high classification accuracy in complete data of model building (algae) species (97.82%, 99.01%) and ranged between 92.50%-94.26% and 92.14%-94.12% in four test species, respectively, whereas regression QSAR models (DTB and DTF) rendered high correlation (R(2)) between the measured and model predicted toxicity end-point values and low mean-squared error in model building (algae) species (0.918, 0.15; 0.905, 0.21) and ranged between 0.575 and 0.672, 0.18-0.51 and 0.605-0.689 and 0.20-0.45 in four different test species. The developed QSAR models exhibited good predictive and generalization abilities in different test species of varied trophic levels and can be used for predicting the toxicities of new chemicals for screening and prioritization of chemicals for regulation. PMID:24738471

  20. Model-based parameterisation of a hydrocyclone air-core

    PubMed

    Podd; Schlaberg; Hoyle

    2000-03-01

    An important metric for the accurate control of a hydrocyclone is the diameter of its air-core. Ultrasonic data from a 16-transducer, 1.5 MHz pulse-echo tomographic system are analysed to determine the variation of the air-core diameter with various operating conditions. The back-projection image reconstruction method is not accurate enough for this task. Sub-millimetre accuracy is obtained, however, by applying a combination of signal processing and model-based reconstruction, using the fact that there is a small variation in the air-core boundary position. The findings correspond well to the results obtained from X-ray and electrical resistance modalities.

  1. A Near-Road Modeling System for Community-Scale Assessments of Traffic-Related AirPollution in the United States

    EPA Science Inventory

    The Community Line Source (C-LINE) modeling system estimates emissions and dispersion of toxic air pollutants for roadways within the continental United States. It accesses publicly available traffic and meteorological datasets, and is optimized for use on community-sized areas (...

  2. MODELS-3 COMMUNITY MULTISCALE AIR QUALITY (CMAQ) MODEL AEROSOL COMPONENT 1: MODEL DESCRIPTION

    EPA Science Inventory

    The aerosol component of the Community Multiscale Air Quality (CMAQ) model is designed to be an efficient and economical depiction of aerosol dynamics in the atmosphere. The approach taken represents the particle size distribution as the superposition of three lognormal subdis...

  3. Urban compaction or dispersion? An air quality modelling study

    NASA Astrophysics Data System (ADS)

    Martins, Helena

    2012-07-01

    Urban sprawl is altering the landscape, with current trends pointing to further changes in land use that will, in turn, lead to changes in population, energy consumption, atmospheric emissions and air quality. Urban planners have debated on the most sustainable urban structure, with arguments in favour and against urban compaction and dispersion. However, it is clear that other areas of expertise have to be involved. Urban air quality and human exposure to atmospheric pollutants as indicators of urban sustainability can contribute to the discussion, namely through the study of the relation between urban structure and air quality. This paper addresses the issue by analysing the impacts of alternative urban growth patterns on the air quality of Porto urban region in Portugal, through a 1-year simulation with the MM5-CAMx modelling system. This region has been experiencing one of the highest European rates of urban sprawl, and at the same time presents a poor air quality. As part of the modelling system setup, a sensitivity study was conducted regarding different land use datasets and spatial distribution of emissions. Two urban development scenarios were defined, SPRAWL and COMPACT, together with their new land use and emission datasets; then meteorological and air quality simulations were performed. Results reveal that SPRAWL land use changes resulted in an average temperature increase of 0.4 °C, with local increases reaching as high as 1.5 °C. SPRAWL results also show an aggravation of PM10 annual average values and an increase in the exceedances to the daily limit value. For ozone, differences between scenarios were smaller, with SPRAWL presenting larger concentration differences than COMPACT. Finally, despite the higher concentrations found in SPRAWL, population exposure to the pollutants is higher for COMPACT because more inhabitants are found in areas of highest concentration levels.

  4. Developing Mental Models about Air Using Inquiry-Based Instruction with Kindergartners

    ERIC Educational Resources Information Center

    Van Hook, Stephen; Huziak, Tracy; Nowak, Katherine

    2005-01-01

    This study examines the development of mental models of air by kindergarten students after completing a series of hands-on, inquiry-based science lessons. The lessons focused on two properties of air: (1) that air takes up space and (2) that it is made of particles ("balls of air"). The students were interviewed about their ideas of air and about…

  5. Impacts of contaminant storage on indoor air quality: Model development

    SciTech Connect

    Sherman, Max H.; Hult, Erin L.

    2013-02-26

    A first-order, lumped capacitance model is used to describe the buffering of airborne chemical species by building materials and furnishings in the indoor environment. The model is applied to describe the interaction between formaldehyde in building materials and the concentration of the species in the indoor air. Storage buffering can decrease the effect of ventilation on the indoor concentration, compared to the inverse dependence of indoor concentration on the air exchange rate that is consistent with a constant emission rate source. If the exposure time of an occupant is long relative to the time scale of depletion of the compound from the storage medium, however, the total exposure will depend inversely on the air exchange rate. This lumped capacitance model is also applied to moisture buffering in the indoor environment, which occurs over much shorter depletion timescales of the order of days. This model provides a framework to interpret the impact of storage buffering on time-varying concentrations of chemical species and resulting occupant exposure. Pseudo-steady state behavior is validated using field measurements. Model behavior over longer times is consistent with formaldehyde and moisture concentration measurements in previous studies.

  6. Toxicity of copper oxide nanoparticles in lung epithelial cells exposed at the air-liquid interface compared with in vivo assessment

    PubMed Central

    Jing, Xuefang; Park, Jae Hong; Peters, Thomas M.; Thorne, Peter S.

    2015-01-01

    The toxicity of spark-generated copper oxide nanoparticles (CuONPs) was evaluated in human bronchial epithelial cells (HBEC) and lung adenocarcinoma cells (A549 cells) using an in vitro air-liquid interface (ALI) exposure system. Dose-response results were compared to in vivo inhalation and instillation studies of CuONP. Cells were exposed to particle-free clean air (controls) or spark-generated CuONPs. The number median diameter, geometric standard deviation and total number concentration of CuONPs were 9.2 nm, 1.48 and 2.27×107 particles/cm3, respectively. Outcome measures included cell viability, cytotoxicity, oxidative stress and proinflammatory chemokine production. Exposure to clean air (2 or 4 hr) did not induce toxicity in HBEC or A549 cells. Compared with controls, CuONP exposures significantly reduced cell viability, increased lactate dehydrogenase (LDH) release and elevated levels of reactive oxygen species (ROS) and IL-8 in a dose-dependent manner. A549 cells were significantly more susceptible to CuONP effects than HBEC. Antioxidant treatment reduced CuONP-induced cytotoxicity. When dose was expressed per area of exposed epithelium there was good agreement of toxicity measures with murine in vivo studies. This demonstrates that in vitro ALI studies can provide meaningful data on nanotoxicity of metal oxides. PMID:25575782

  7. Impact of High Resolution Land-Use Data in Meteorology and Air Quality Modeling Systems

    EPA Science Inventory

    Accurate land use information is important in meteorology for land surface exchanges, in emission modeling for emission spatial allocation, and in air quality modeling for chemical surface fluxes. Currently, meteorology, emission, and air quality models often use outdated USGS Gl...

  8. Insecticide toxicity to Hyalella curvispina in runoff and stream water within a soybean farm (Buenos Aires, Argentina).

    PubMed

    Mugni, H; Ronco, A; Bonetto, C

    2011-03-01

    Toxicity to the locally dominant amphipod Hyalella curvispina was assessed in a first-order stream running through a cultivated farm. Cypermethrin, chlorpyrifos, endosulfan and glyphosate were sprayed throughout the studied period. Toxicity was assayed under controlled laboratory conditions with runoff and stream water samples taken from the field under steady state and flood conditions. Ephemeral toxicity pulses were observed as a consequence of farm pesticide applications. After pesticide application, runoff water showed 100% mortality to H. curvispina for 1 month, but no mortality thereafter. Toxicity persistence was shortest in stream water, intermediate in stream sediments and longest in soil samples. Runoff had a more important toxicity effect than the exposure to direct aerial fumigation. The regional environmental features determining fast toxicity dissipation are discussed.

  9. A rabbit model of toxic shock syndrome that uses a constant, subcutaneous infusion of toxic shock syndrome toxin 1.

    PubMed

    Parsonnet, J; Gillis, Z A; Richter, A G; Pier, G B

    1987-05-01

    We have developed a rabbit model of toxic shock syndrome that uses a subcutaneous infusion pump to administer toxic shock syndrome toxin 1 (TSST-1). A dose of 150 micrograms, infused at a constant rate over a period of 7 days, resulted in a characteristic illness highlighted by fever, conjunctival hyperemia, cachexia, and lethargy. The illness was uniformly fatal, with a mean interval until death of 3.2 +/- 0.4 days. Serial determinations of serum chemistries confirmed the multisystem nature of this illness. Rabbits developed profound hypocalcemia, with levels falling from 15.5 +/- 0.2 to 7.6 +/- 0.4 mg/dl under the influence of TSST-1. Blood urea nitrogen and creatinine rose dramatically, in the setting of oliguria or anuria. Serum glutamicpyruvic transaminase was the most reliable indicator of hepatic dysfunction, with the mean rising from 48 U/liter before administration of TSST-1 to 546 U/liter among rabbits surviving 2 days of the infusion. Creatine phosphokinase also rose dramatically in 10 of 16 rabbits. Rabbits demonstrated relative neutrophilia and lymphopenia as well as an increase in the partial thromboplastin time. Histopathologic examination demonstrated disease of multiple organs, particularly the liver, spleen, and lymph nodes, all of which demonstrated inflammation, thrombosis, hemorrhage, and erythrophagocytosis. The concurrent administration of prednisolone with TSST-1 prevented death in four of four rabbits and greatly lessened the morbidity. Rabbits were not protected from morbidity or mortality by the concurrent administration of polymyxin B. We believe that a constant, subcutaneous infusion of TSST-1 in rabbits provides a reproducible model for studying the pathogenesis of TSS.

  10. Review of Air Exchange Rate Models for Air Pollution Exposure Assessments

    EPA Science Inventory

    A critical aspect of air pollution exposure assessments is estimation of the air exchange rate (AER) for various buildings, where people spend their time. The AER, which is rate the exchange of indoor air with outdoor air, is an important determinant for entry of outdoor air pol...

  11. Aviation System Analysis Capability Air Carrier Investment Model-Cargo

    NASA Technical Reports Server (NTRS)

    Johnson, Jesse; Santmire, Tara

    1999-01-01

    The purpose of the Aviation System Analysis Capability (ASAC) Air Cargo Investment Model-Cargo (ACIMC), is to examine the economic effects of technology investment on the air cargo market, particularly the market for new cargo aircraft. To do so, we have built an econometrically based model designed to operate like the ACIM. Two main drivers account for virtually all of the demand: the growth rate of the Gross Domestic Product (GDP) and changes in the fare yield (which is a proxy of the price charged or fare). These differences arise from a combination of the nature of air cargo demand and the peculiarities of the air cargo market. The net effect of these two factors are that sales of new cargo aircraft are much less sensitive to either increases in GDP or changes in the costs of labor, capital, fuel, materials, and energy associated with the production of new cargo aircraft than the sales of new passenger aircraft. This in conjunction with the relatively small size of the cargo aircraft market means technology improvements to the cargo aircraft will do relatively very little to spur increased sales of new cargo aircraft.

  12. A Zebrafish Model for Uremic Toxicity: Role of the Complement Pathway

    PubMed Central

    Thurman, Josh; Reinecke, James; Raff, Amanda C.; Melamed, Michal L.; Reinecke, James; Quan, Zhe; Evans, Todd; Meyer, Timothy W.; Hostetter, Thomas H

    2016-01-01

    Many organic solutes accumulate in ESRD and some are poorly removed removed with urea based prescriptions for hemodialysis. However, their toxicities have been difficult to assess. We have employed an animal model, the zebrafish embryo, to test the toxicity of uremic serum compared to control. Serum was obtained from stable ESRD patients pre-dialysis or from normal subjects. Zebrafish embryos 24 hours post fertilization were exposed to experimental media at a ratio of 3:1 water:human serum. Those exposed to serum from uremic subjects had significantly reduced survival at 8 hours (19% +/− 18% vs. 94% +/− 6%; p < 0.05, uremic serum vs control, respectively). Embryos exposed to serum from ESRD subjects fractionated at 50kD showed significantly greater toxicity with the larger molecular weight fraction (83% +/− 11% vs 7% +/−17% survival, p < 0.05, <50kD vs >50 kD, respectively). Heating serum abrogated its toxicity. EDTA, a potent inhibitor of complement by virtue of calcium chelation, reduced the toxicity of uremic serum compared to untreated uremic serum (96%+/− 5% vs 28%+/− 20% survival, p < 0.016, chelated vs non chelated serum respectively). Anti- factor B, a specific inhibitor of the alternative complement pathway, reduced the toxicity of uremic serum, compared to untreated uremic serum (98% +/− 6% vs. 3% +/− 9% survival, p < 0.016, anti- factor B treated vs non treated, respectively).Uremic serum is thus more toxic to zebrafish embryos than normal serum. Furthermore, this toxicity is associated with a fraction of large size, is inactivated by heat, and is reduced by both specific and non-specific inhibitors of complement activation. Together these data lend support to the hypothesis that at least some uremic toxicities may be mediated by complement. PMID:23689420

  13. A zebrafish model for uremic toxicity: role of the complement pathway.

    PubMed

    Berman, Nathaniel; Lectura, Melisa; Thurman, Joshua M; Reinecke, James; Raff, Amanda C; Melamed, Michal L; Quan, Zhe; Evans, Todd; Meyer, Timothy W; Hostetter, Thomas H

    2013-01-01

    Many organic solutes accumulate in end-stage renal disease (ESRD) and some are poorly removed with urea-based prescriptions for hemodialysis. However, their toxicities have been difficult to assess. We have employed an animal model, the zebrafish embryo, to test the toxicity of uremic serum compared to control. Serum was obtained from stable ESRD patients predialysis or from normal subjects. Zebrafish embryos 24 h postfertilization were exposed to experimental media at a water:human serum ratio of 3:1. Those exposed to serum from uremic subjects had significantly reduced survival at 8 h (19 ± 18 vs. 94 ± 6%, p < 0.05, uremic serum vs. control, respectively). Embryos exposed to serum from ESRD subjects fractionated at 50 kDa showed significantly greater toxicity with the larger molecular weight fraction (83 ± 11 vs. 7 ± 17% survival, p < 0.05, <50 vs. >50 kDa, respectively). Heating serum abrogated its toxicity. EDTA, a potent inhibitor of complement by virtue of calcium chelation, reduced the toxicity of uremic serum compared to untreated uremic serum (96 ± 5 vs. 28 ± 20% survival, p < 0.016, chelated vs. nonchelated serum, respectively). Anti-factor B, a specific inhibitor of the alternative complement pathway, reduced the toxicity of uremic serum, compared to untreated uremic serum (98 ± 6 vs. 3 ± 9% survival, p < 0.016, anti-factor B treated vs. nontreated, respectively). Uremic serum is thus more toxic to zebrafish embryos than normal serum. Furthermore, this toxicity is associated with a fraction of large size, is inactivated by heat, and is reduced by both specific and nonspecific inhibitors of complement activation. Together these data lend support to the hypothesis that at least some uremic toxicities may be mediated by complement.

  14. A zebrafish model for uremic toxicity: role of the complement pathway.

    PubMed

    Berman, Nathaniel; Lectura, Melisa; Thurman, Joshua M; Reinecke, James; Raff, Amanda C; Melamed, Michal L; Quan, Zhe; Evans, Todd; Meyer, Timothy W; Hostetter, Thomas H

    2013-01-01

    Many organic solutes accumulate in end-stage renal disease (ESRD) and some are poorly removed with urea-based prescriptions for hemodialysis. However, their toxicities have been difficult to assess. We have employed an animal model, the zebrafish embryo, to test the toxicity of uremic serum compared to control. Serum was obtained from stable ESRD patients predialysis or from normal subjects. Zebrafish embryos 24 h postfertilization were exposed to experimental media at a water:human serum ratio of 3:1. Those exposed to serum from uremic subjects had significantly reduced survival at 8 h (19 ± 18 vs. 94 ± 6%, p < 0.05, uremic serum vs. control, respectively). Embryos exposed to serum from ESRD subjects fractionated at 50 kDa showed significantly greater toxicity with the larger molecular weight fraction (83 ± 11 vs. 7 ± 17% survival, p < 0.05, <50 vs. >50 kDa, respectively). Heating serum abrogated its toxicity. EDTA, a potent inhibitor of complement by virtue of calcium chelation, reduced the toxicity of uremic serum compared to untreated uremic serum (96 ± 5 vs. 28 ± 20% survival, p < 0.016, chelated vs. nonchelated serum, respectively). Anti-factor B, a specific inhibitor of the alternative complement pathway, reduced the toxicity of uremic serum, compared to untreated uremic serum (98 ± 6 vs. 3 ± 9% survival, p < 0.016, anti-factor B treated vs. nontreated, respectively). Uremic serum is thus more toxic to zebrafish embryos than normal serum. Furthermore, this toxicity is associated with a fraction of large size, is inactivated by heat, and is reduced by both specific and nonspecific inhibitors of complement activation. Together these data lend support to the hypothesis that at least some uremic toxicities may be mediated by complement. PMID:23689420

  15. Modifications to toxic CUG RNAs induce structural stability, rescue mis-splicing in a myotonic dystrophy cell model and reduce toxicity in a myotonic dystrophy zebrafish model

    DOE PAGES

    deLorimier, Elaine; Coonrod, Leslie A.; Copperman, Jeremy; Taber, Alex; Reister, Emily E.; Sharma, Kush; Todd, Peter K.; Guenza, Marina G.; Berglund, J. Andrew

    2014-10-10

    In this study, CUG repeat expansions in the 3' UTR of dystrophia myotonica protein kinase (DMPK) cause myotonic dystrophy type 1 (DM1). As RNA, these repeats elicit toxicity by sequestering splicing proteins, such as MBNL1, into protein–RNA aggregates. Structural studies demonstrate that CUG repeats can form A-form helices, suggesting that repeat secondary structure could be important in pathogenicity. To evaluate this hypothesis, we utilized structure-stabilizing RNA modifications pseudouridine (Ψ) and 2'-O-methylation to determine if stabilization of CUG helical conformations affected toxicity. CUG repeats modified with Ψ or 2'-O-methyl groups exhibited enhanced structural stability and reduced affinity for MBNL1. Molecular dynamicsmore » and X-ray crystallography suggest a potential water-bridging mechanism for Ψ-mediated CUG repeat stabilization. Ψ modification of CUG repeats rescued mis-splicing in a DM1 cell model and prevented CUG repeat toxicity in zebrafish embryos. This study indicates that the structure of toxic RNAs has a significant role in controlling the onset of neuromuscular diseases.« less

  16. Modifications to toxic CUG RNAs induce structural stability, rescue mis-splicing in a myotonic dystrophy cell model and reduce toxicity in a myotonic dystrophy zebrafish model

    SciTech Connect

    deLorimier, Elaine; Coonrod, Leslie A.; Copperman, Jeremy; Taber, Alex; Reister, Emily E.; Sharma, Kush; Todd, Peter K.; Guenza, Marina G.; Berglund, J. Andrew

    2014-10-10

    In this study, CUG repeat expansions in the 3' UTR of dystrophia myotonica protein kinase (DMPK) cause myotonic dystrophy type 1 (DM1). As RNA, these repeats elicit toxicity by sequestering splicing proteins, such as MBNL1, into protein–RNA aggregates. Structural studies demonstrate that CUG repeats can form A-form helices, suggesting that repeat secondary structure could be important in pathogenicity. To evaluate this hypothesis, we utilized structure-stabilizing RNA modifications pseudouridine (Ψ) and 2'-O-methylation to determine if stabilization of CUG helical conformations affected toxicity. CUG repeats modified with Ψ or 2'-O-methyl groups exhibited enhanced structural stability and reduced affinity for MBNL1. Molecular dynamics and X-ray crystallography suggest a potential water-bridging mechanism for Ψ-mediated CUG repeat stabilization. Ψ modification of CUG repeats rescued mis-splicing in a DM1 cell model and prevented CUG repeat toxicity in zebrafish embryos. This study indicates that the structure of toxic RNAs has a significant role in controlling the onset of neuromuscular diseases.

  17. Modifications to toxic CUG RNAs induce structural stability, rescue mis-splicing in a myotonic dystrophy cell model and reduce toxicity in a myotonic dystrophy zebrafish model.

    PubMed

    deLorimier, Elaine; Coonrod, Leslie A; Copperman, Jeremy; Taber, Alex; Reister, Emily E; Sharma, Kush; Todd, Peter K; Guenza, Marina G; Berglund, J Andrew

    2014-11-10

    CUG repeat expansions in the 3' UTR of dystrophia myotonica protein kinase (DMPK) cause myotonic dystrophy type 1 (DM1). As RNA, these repeats elicit toxicity by sequestering splicing proteins, such as MBNL1, into protein-RNA aggregates. Structural studies demonstrate that CUG repeats can form A-form helices, suggesting that repeat secondary structure could be important in pathogenicity. To evaluate this hypothesis, we utilized structure-stabilizing RNA modifications pseudouridine (Ψ) and 2'-O-methylation to determine if stabilization of CUG helical conformations affected toxicity. CUG repeats modified with Ψ or 2'-O-methyl groups exhibited enhanced structural stability and reduced affinity for MBNL1. Molecular dynamics and X-ray crystallography suggest a potential water-bridging mechanism for Ψ-mediated CUG repeat stabilization. Ψ modification of CUG repeats rescued mis-splicing in a DM1 cell model and prevented CUG repeat toxicity in zebrafish embryos. This study indicates that the structure of toxic RNAs has a significant role in controlling the onset of neuromuscular diseases. PMID:25303993

  18. Ecotoxicogenomic Approaches for Understanding Molecular Mechanisms of Environmental Chemical Toxicity Using Aquatic Invertebrate, Daphnia Model Organism

    PubMed Central

    Kim, Hyo Jeong; Koedrith, Preeyaporn; Seo, Young Rok

    2015-01-01

    Due to the rapid advent in genomics technologies and attention to ecological risk assessment, the term “ecotoxicogenomics” has recently emerged to describe integration of omics studies (i.e., transcriptomics, proteomics, metabolomics, and epigenomics) into ecotoxicological fields. Ecotoxicogenomics is defined as study of an entire set of genes or proteins expression in ecological organisms to provide insight on environmental toxicity, offering benefit in ecological risk assessment. Indeed, Daphnia is a model species to study aquatic environmental toxicity designated in the Organization for Economic Co-operation and Development’s toxicity test guideline and to investigate expression patterns using ecotoxicology-oriented genomics tools. Our main purpose is to demonstrate the potential utility of gene expression profiling in ecotoxicology by identifying novel biomarkers and relevant modes of toxicity in Daphnia magna. These approaches enable us to address adverse phenotypic outcomes linked to particular gene function(s) and mechanistic understanding of aquatic ecotoxicology as well as exploration of useful biomarkers. Furthermore, key challenges that currently face aquatic ecotoxicology (e.g., predicting toxicant responses among a broad spectrum of phytogenetic groups, predicting impact of temporal exposure on toxicant responses) necessitate the parallel use of other model organisms, both aquatic and terrestrial. By investigating gene expression profiling in an environmentally important organism, this provides viable support for the utility of ecotoxicogenomics. PMID:26035755

  19. Mechanistic quantitative structure-activity relationship model for the photoinduced toxicity of polycyclic aromatic hydrocarbons. 2: An empirical model for the toxicity of 16 polycyclic aromatic hydrocarbons to the duckweed Lemna gibba L. G-3

    SciTech Connect

    Huang, X.D.; Krylov, S.N.; Ren, L.; McConkey, B.J.; Dixon, D.G.; Greenberg, B.M.

    1997-11-01

    Photoinduced toxicity of polycyclic aromatic hydrocarbons (PAHs) occurs via photosensitization reactions (e.g., generation of singlet-state oxygen) and by photomodification (photooxidation and/or photolysis) of the chemicals to more toxic species. The quantitative structure-activity relationship (QSAR) described in the companion paper predicted, in theory, that photosensitization and photomodification additively contribute to toxicity. To substantiate this QSAR modeling exercise it was necessary to show that toxicity can be described by empirically derived parameters. The toxicity of 16 PAHs to the duckweed Lemna gibba was measured as inhibition of leaf production in simulated solar radiation (a light source with a spectrum similar to that of sunlight). A predictive model for toxicity was generated based on the theoretical model developed in the companion paper. The photophysical descriptors required of each PAH for modeling were efficiency of photon absorbance, relative uptake, quantum yield for triplet-state formation, and the rate of photomodification. The photomodification rates of the PAHs showed a moderate correlation to toxicity, whereas a derived photosensitization factor (PSF; based on absorbance, triplet-state quantum yield, and uptake) for each PAH showed only a weak, complex correlation to toxicity. However, summing the rate of photomodification and the PSF resulted in a strong correlation to toxicity that had predictive value. When the PSF and a derived photomodification factor (PMF; based on the photomodification rate and toxicity of the photomodified PAHs) were summed, an excellent explanatory model of toxicity was produced, substantiating the additive contributions of the two factors.

  20. Application of Generalized Linear Models to the Analysis of Toxicity Test Data.

    ERIC Educational Resources Information Center

    Maul, A.

    1992-01-01

    Studies binomial, negative binomial, and gamma regression models and gives a detailed description of inference procedures based on them. The process of model fitting and evaluation is illustrated by examples referring to the determination of endpoints in acute and chronic toxicity tests. (17 references) (Author/MDH)

  1. New Methods for Air Quality Model Evaluation with Satellite Data

    NASA Astrophysics Data System (ADS)

    Holloway, T.; Harkey, M.

    2015-12-01

    Despite major advances in the ability of satellites to detect gases and aerosols in the atmosphere, there remains significant, untapped potential to apply space-based data to air quality regulatory applications. Here, we showcase research findings geared toward increasing the relevance of satellite data to support operational air quality management, focused on model evaluation. Particular emphasis is given to nitrogen dioxide (NO2) and formaldehyde (HCHO) from the Ozone Monitoring Instrument aboard the NASA Aura satellite, and evaluation of simulations from the EPA Community Multiscale Air Quality (CMAQ) model. This work is part of the NASA Air Quality Applied Sciences Team (AQAST), and is motivated by ongoing dialog with state and federal air quality management agencies. We present the response of satellite-derived NO2 to meteorological conditions, satellite-derived HCHO:NO2 ratios as an indicator of ozone production regime, and the ability of models to capture these sensitivities over the continental U.S. In the case of NO2-weather sensitivities, we find boundary layer height, wind speed, temperature, and relative humidity to be the most important variables in determining near-surface NO2 variability. CMAQ agreed with relationships observed in satellite data, as well as in ground-based data, over most regions. However, we find that the southwest U.S. is a problem area for CMAQ, where modeled NO2 responses to insolation, boundary layer height, and other variables are at odds with the observations. Our analyses utilize a software developed by our team, the Wisconsin Horizontal Interpolation Program for Satellites (WHIPS): a free, open-source program designed to make satellite-derived air quality data more usable. WHIPS interpolates level 2 satellite retrievals onto a user-defined fixed grid, in effect creating custom-gridded level 3 satellite product. Currently, WHIPS can process the following data products: OMI NO2 (NASA retrieval); OMI NO2 (KNMI retrieval); OMI

  2. Modulation of mitochondrial bioenergetics in a skeletal muscle cell line model of mitochondrial toxicity.

    PubMed

    Dott, William; Mistry, Pratibha; Wright, Jayne; Cain, Kelvin; Herbert, Karl E

    2014-01-01

    Mitochondrial toxicity is increasingly being implicated as a contributing factor to many xenobiotic-induced organ toxicities, including skeletal muscle toxicity. This has necessitated the need for predictive in vitro models that are able to sensitively detect mitochondrial toxicity of chemical entities early in the research and development process. One such cell model involves substituting galactose for glucose in the culture media. Since cells cultured in galactose are unable to generate sufficient ATP from glycolysis they are forced to rely on mitochondrial oxidative phosphorylation for ATP generation and consequently are more sensitive to mitochondrial perturbation than cells grown in glucose. The aim of this study was to characterise cellular growth, bioenergetics and mitochondrial toxicity of the L6 rat skeletal muscle cell line cultured in either high glucose or galactose media. L6 myoblasts proliferated more slowly when cultured in galactose media, although they maintained similar levels of ATP. Galactose cultured L6 cells were significantly more sensitive to classical mitochondrial toxicants than glucose-cultured cells, confirming the cells had adapted to galactose media. Analysis of bioenergetic function with the XF Seahorse extracellular flux analyser demonstrated that oxygen consumption rate (OCR) was significantly increased whereas extracellular acidification rate (ECAR), a measure of glycolysis, was decreased in cells grown in galactose. Mitochondria operated closer to state 3 respiration and had a lower mitochondrial membrane potential and basal mitochondrial O2 (•-) level compared to cells in the glucose model. An antimycin A (AA) dose response revealed that there was no difference in the sensitivity of OCR to AA inhibition between glucose and galactose cells. Importantly, cells in glucose were able to up-regulate glycolysis, while galactose cells were not. These results confirm that L6 cells are able to adapt to growth in a galactose media model

  3. The Virtual Liver: Modeling Chemical-Induced Liver Toxicity

    EPA Science Inventory

    The US EPA Virtual Liver (v-Liver) project is aimed at modeling chemical-induced processes in hepatotoxicity and simulating their dose-dependent perturbations. The v-Liver embodies an emerging field of research in computational tissue modeling that integrates molecular and cellul...

  4. Mathematical modeling of a primary zinc/air battery

    SciTech Connect

    Mao, Z.; White, R.E. )

    1992-04-01

    This paper reports on the mathematical model developed by Sunu and Bennion that has been extended to include the separator, precipitation of both solid ZnO and K{sub 2}Zn(OH){sub 4}, and the air electrode, and has been used to investigate the behavior of a primary Zn-Air battery with respect to battery design features. Predictions obtained from the model indicate that anode material utilization is predominantly limited by depletion of the concentration of hydroxide ions. The effect of electrode thickness on anode material utilization is insignificant, whereas material loading per unit volume has a great effect on anode material utilization; a higher loading lowers both the anode material utilization and delivered capacity. Use of a thick separator will increase the anode material utilization, but may reduce the cell voltage.

  5. Mathematical modeling of a primary zinc/air battery

    NASA Astrophysics Data System (ADS)

    Mao, Z.; White, R. E.

    1992-04-01

    The mathematical model developed by Sunu and Bennion has been extended to include the separator, precipitation of both solid ZnO and K2Zn(OH)4, and the air electrode, and has been used to investigate the behavior of a primary Zn-Air battery with respect to battery design features. Predictions obtained from the model indicate that anode material utilization is predominantly limited by depletion of the concentration of hydroxide ions. The effect of electrode thickness on anode material utilization is insignificant, whereas material loading per unit volume has a great effect on anode material utilization; a higher loading lowers both the anode material utilization and delivered capacity. Use of a thick separator will increase the anode material utilization, but may reduce the cell voltage.

  6. Mathematical modeling of a primary zinc/air battery

    NASA Technical Reports Server (NTRS)

    Mao, Z.; White, R. E.

    1992-01-01

    The mathematical model developed by Sunu and Bennion has been extended to include the separator, precipitation of both solid ZnO and K2Zn(OH)4, and the air electrode, and has been used to investigate the behavior of a primary Zn-Air battery with respect to battery design features. Predictions obtained from the model indicate that anode material utilization is predominantly limited by depletion of the concentration of hydroxide ions. The effect of electrode thickness on anode material utilization is insignificant, whereas material loading per unit volume has a great effect on anode material utilization; a higher loading lowers both the anode material utilization and delivered capacity. Use of a thick separator will increase the anode material utilization, but may reduce the cell voltage.

  7. A 26-Week Toxicity Assessment of AIR001 (Sodium Nitrite) by Inhalation Exposure in Rats and by Intravenous Administration in Dogs.

    PubMed

    Tepper, Jeffrey; Ochoa, Ricardo; Rix, Peter; Elliott, Gary; Hoglen, Niel; Poulin, Dominic; Parsley, Ed; Masamune, Hiroko

    2014-05-01

    Historically, nitrogen oxides (NOx) in food, drinking water, as well as in the atmosphere have been believed to be associated with adverse health consequences. More recently, NOx have been implicated in normal homeostatic regulation, and exogenous administration has been associated with health benefits. One such potential health benefit is the prospect that inhaled nitrite will lower pulmonary blood pressure (BP) in patients with pulmonary arterial hypertension (PAH), a disease with poor prognosis due to the lack of effective treatment. To characterize potential chronic toxicity associated with inhaled AIR001 (sodium nitrite) for use in the treatment of PAH, 26-week exposures to AIR001 were carried out by inhalation administration in rats and by intravenous infusion in dogs. The studies revealed that methemoglobinemia was the primary adverse effect in both species. Methemoglobin levels less than 40% were well tolerated in both species, while levels greater than 50% methemoglobin caused death in some rats. Additionally, a decrease in systemic BP was also observed with inhaled AIR001 exposure in dogs. These acute secondary and exaggerated pharmacological effects occurred daily throughout the 26-week treatment period. Chronic exposure did not alter the magnitude of either methemoglobinemia or hypotension or result in additional toxicity or compensatory responses. Based on the exposure levels that produced these pharmacodynamic responses in animals, relative to those measured in early clinical studies, it appears that an adequate margin of safety exists to support the continued clinical development of inhaled AIR001.

  8. Curve fitting toxicity test data: Which comes first, the dose response or the model?

    SciTech Connect

    Gully, J.; Baird, R.; Bottomley, J.

    1995-12-31

    The probit model frequently does not fit the concentration-response curve of NPDES toxicity test data and non-parametric models must be used instead. The non-parametric models, trimmed Spearman-Karber, IC{sub p}, and linear interpolation, all require a monotonic concentration-response. Any deviation from a monotonic response is smoothed to obtain the desired concentration-response characteristics. Inaccurate point estimates may result from such procedures and can contribute to imprecision in replicate tests. The following study analyzed reference toxicant and effluent data from giant kelp (Macrocystis pyrifera), purple sea urchin (Strongylocentrotus purpuratus), red abalone (Haliotis rufescens), and fathead minnow (Pimephales promelas) bioassays using commercially available curve fitting software. The purpose was to search for alternative parametric models which would reduce the use of non-parametric models for point estimate analysis of toxicity data. Two non-linear models, power and logistic dose-response, were selected as possible alternatives to the probit model based upon their toxicological plausibility and ability to model most data sets examined. Unlike non-parametric procedures, these and all parametric models can be statistically evaluated for fit and significance. The use of the power or logistic dose response models increased the percentage of parametric model fits for each protocol and toxicant combination examined. The precision of the selected non-linear models was also compared with the EPA recommended point estimation models at several effect.levels. In general, precision of the alternative models was equal to or better than the traditional methods. Finally, use of the alternative models usually produced more plausible point estimates in data sets where the effects of smoothing and non-parametric modeling made the point estimate results suspect.

  9. Comparison of stationary and personal air sampling with an air dispersion model for children's ambient exposure to manganese.

    PubMed

    Fulk, Florence; Haynes, Erin N; Hilbert, Timothy J; Brown, David; Petersen, Dan; Reponen, Tiina

    2016-09-01

    Manganese (Mn) is ubiquitous in the environment and essential for normal growth and development, yet excessive exposure can lead to impairments in neurological function. This study modeled ambient Mn concentrations as an alternative to stationary and personal air sampling to assess exposure for children enrolled in the Communities Actively Researching Exposure Study in Marietta, OH. Ambient air Mn concentration values were modeled using US Environmental Protection Agency's Air Dispersion Model AERMOD based on emissions from the ferromanganese refinery located in Marietta. Modeled Mn concentrations were compared with Mn concentrations from a nearby stationary air monitor. The Index of Agreement for modeled versus monitored data was 0.34 (48 h levels) and 0.79 (monthly levels). Fractional bias was 0.026 for 48 h levels and -0.019 for monthly levels. The ratio of modeled ambient air Mn to measured ambient air Mn at the annual time scale was 0.94. Modeled values were also time matched to personal air samples for 19 children. The modeled values explained a greater degree of variability in personal exposures compared with time-weighted distance from the emission source. Based on these results modeled Mn concentrations provided a suitable approach for assessing airborne Mn exposure in this cohort. PMID:27168393

  10. Comparison of stationary and personal air sampling with an air dispersion model for children's ambient exposure to manganese.

    PubMed

    Fulk, Florence; Haynes, Erin N; Hilbert, Timothy J; Brown, David; Petersen, Dan; Reponen, Tiina

    2016-09-01

    Manganese (Mn) is ubiquitous in the environment and essential for normal growth and development, yet excessive exposure can lead to impairments in neurological function. This study modeled ambient Mn concentrations as an alternative to stationary and personal air sampling to assess exposure for children enrolled in the Communities Actively Researching Exposure Study in Marietta, OH. Ambient air Mn concentration values were modeled using US Environmental Protection Agency's Air Dispersion Model AERMOD based on emissions from the ferromanganese refinery located in Marietta. Modeled Mn concentrations were compared with Mn concentrations from a nearby stationary air monitor. The Index of Agreement for modeled versus monitored data was 0.34 (48 h levels) and 0.79 (monthly levels). Fractional bias was 0.026 for 48 h levels and -0.019 for monthly levels. The ratio of modeled ambient air Mn to measured ambient air Mn at the annual time scale was 0.94. Modeled values were also time matched to personal air samples for 19 children. The modeled values explained a greater degree of variability in personal exposures compared with time-weighted distance from the emission source. Based on these results modeled Mn concentrations provided a suitable approach for assessing airborne Mn exposure in this cohort.

  11. Human alveolar epithelial cells expressing tight junctions to model the air-blood barrier.

    PubMed

    Kuehn, Anna; Kletting, Stephanie; de Souza Carvalho-Wodarz, Cristiane; Repnik, Urska; Griffiths, Gareth; Fischer, Ulrike; Meese, Eckart; Huwer, Hanno; Wirth, Dagmar; May, Tobias; Schneider-Daum, Nicole; Lehr, Claus-Michael

    2016-01-01

    This paper describes a new human alveolar epithelial cell line (hAELVi - human Alveolar Epithelial Lentivirus immortalized) with type I-like characteristics and functional tight junctions, suitable to model the air-blood barrier of the peripheral lung. Primary human alveolar epithelial cells were immortalized by a novel regimen, grown as monolayers on permeable filter supports and characterized morphologically, biochemically and biophysically. hAELVi cells maintain the capacity to form tight intercellular junctions, with high trans-epithelial electrical resistance (> 1000 Ω*cm²). The cells could be kept in culture over several days, up to passage 75, under liquid-liquid as well as air-liquid conditions. Ultrastructural analysis and real time PCR revealed type I-like cell properties, such as the presence of caveolae, expression of caveolin-1, and absence of surfactant protein C. Accounting for the barrier properties, inter-digitations sealed with tight junctions and desmosomes were also observed. Low permeability of the hydrophilic marker sodium fluorescein confirmed the suitability of hAELVi cells for in vitro transport studies across the alveolar epithelium. These results suggest that hAELVi cells reflect the essential features of the air-blood barrier, as needed for an alternative to animal testing to study absorption and toxicity of inhaled drugs, chemicals and nanomaterials. PMID:26985677

  12. Modeling toxicity due to intermittent exposure of rainbow trout and common shiners to monochloramine

    SciTech Connect

    Meyer, J.S.; Gulley, D.D. . Dept. of Zoology and Physiology); Goodrich, M.S. ); Szmania, D.C.; Brooks, A.S. . Center for Great Lakes Studies)

    1995-01-01

    The authors evaluated the ability of three mathematical models to predict toxicity to common shiners and rainbow trout during intermittent (pulsed) exposures to monochloramine, based on data from continuous-exposure toxicity tests. If a power term for the exposure-water concentration was included in the models, a concentration x time (Cxt) model and the Mancini uptake-depuration model predicted pulse LC50s to within [+-]50% of the observed pulse LC50s, for the first four pulses in toxicity tests with 2-h pulse/22-h recovery cycles. Beyond the fourth pulse cycle, though, the pulse LC50s predicted using the Cxt model appeared to diverge considerably from the trend of the experimental pulse LC50s, partly because this model does not predict an incipient lethal level (C[sub ILL]) for either continuous or intermittent exposures. The Mancini model predicted the C[sub ILL] moderately well in the common shiner intermittent-exposure test but not in the rainbow trout intermittent-exposure test. The Breck three-dimensional damage-repair model did not predict pulse LC50 or C[sub ILL] values as well as did the other two models, probably because not enough partial-mortality data were available to parameterize the model adequately. Although the underlying processes appear to be more complex than what these simple models assume, the models may still be adequate for use in regulating a few pulse discharges of monochloramine.

  13. NASA/MSFC multilayer diffusion models and computer program for operational prediction of toxic fuel hazards

    NASA Technical Reports Server (NTRS)

    Dumbauld, R. K.; Bjorklund, J. R.; Bowers, J. F.

    1973-01-01

    The NASA/MSFC multilayer diffusion models are discribed which are used in applying meteorological information to the estimation of toxic fuel hazards resulting from the launch of rocket vehicle and from accidental cold spills and leaks of toxic fuels. Background information, definitions of terms, description of the multilayer concept are presented along with formulas for determining the buoyant rise of hot exhaust clouds or plumes from conflagrations, and descriptions of the multilayer diffusion models. A brief description of the computer program is given, and sample problems and their solutions are included. Derivations of the cloud rise formulas, users instructions, and computer program output lists are also included.

  14. Space-Time Fusion Under Error in Computer Model Output: An Application to Modeling Air Quality

    EPA Science Inventory

    In the last two decades a considerable amount of research effort has been devoted to modeling air quality with public health objectives. These objectives include regulatory activities such as setting standards along with assessing the relationship between exposure to air pollutan...

  15. QSTR modeling for qualitative and quantitative toxicity predictions of diverse chemical pesticides in honey bee for regulatory purposes.

    PubMed

    Singh, Kunwar P; Gupta, Shikha; Basant, Nikita; Mohan, Dinesh

    2014-09-15

    Pesticides are designed toxic chemicals for specific purposes and can harm nontarget species as well. The honey bee is considered a nontarget test species for toxicity evaluation of chemicals. Global QSTR (quantitative structure-toxicity relationship) models were established for qualitative and quantitative toxicity prediction of pesticides in honey bee (Apis mellifera) based on the experimental toxicity data of 237 structurally diverse pesticides. Structural diversity of the chemical pesticides and nonlinear dependence in the toxicity data were evaluated using the Tanimoto similarity index and Brock-Dechert-Scheinkman statistics. Probabilistic neural network (PNN) and generalized regression neural network (GRNN) QSTR models were constructed for classification (two and four categories) and function optimization problems using the toxicity end point in honey bees. The predictive power of the QSTR models was tested through rigorous validation performed using the internal and external procedures employing a wide series of statistical checks. In complete data, the PNN-QSTR model rendered a classification accuracy of 96.62% (two-category) and 95.57% (four-category), while the GRNN-QSTR model yielded a correlation (R(2)) of 0.841 between the measured and predicted toxicity values with a mean squared error (MSE) of 0.22. The results suggest the appropriateness of the developed QSTR models for reliably predicting qualitative and quantitative toxicities of pesticides in honey bee. Both the PNN and GRNN based QSTR models constructed here can be useful tools in predicting the qualitative and quantitative toxicities of the new chemical pesticides for regulatory purposes.

  16. Zebrafish: as an integrative model for twenty-first century toxicity testing.

    PubMed

    Sipes, Nisha S; Padilla, Stephanie; Knudsen, Thomas B

    2011-09-01

    The zebrafish embryo is a useful small model for investigating vertebrate development because of its transparency, low cost, transgenic and morpholino capabilities, conservation of cell signaling, and concordance with mammalian developmental phenotypes. From these advantages, the zebrafish embryo has been considered as an alternative model for traditional in vivo developmental toxicity screening. The use of this organism in conjunction with traditional in vivo developmental toxicity testing has the potential to reduce cost and increase throughput of testing the chemical universe, prioritize chemicals for targeted toxicity testing, generate predictive models of developmental toxicants, and elucidate mechanisms and adverse outcome pathways for abnormal development. This review gives an overview of the zebrafish embryo for pre dictive toxicology and 21st century toxicity testing. Developmental eye defects were selected as an example to evaluate data from the U.S. Environmental Protection Agency's ToxCast program comparing responses in zebrafish embryos with those from pregnant rats and rabbits for a subset of 24 environmental chemicals across >600 in vitro assay targets. Cross-species comparisons implied a common basis for biological pathways associated with neuronal defects, extracellular matrix remodeling, and mitotic arrest. PMID:21932434

  17. Quantitative structure-activity relationship modelling of oral acute toxicity and cytotoxic activity of fragrance materials in rodents.

    PubMed

    Papa, E; Luini, M; Gramatica, P

    2009-10-01

    Fragrance materials are used as ingredients in many consumer and personal care products. The wide and daily use of these substances, as well as their mainly uncontrolled discharge through domestic sewage, make fragrance materials both potential indoor and outdoor air pollutants which are also connected to possible toxic effects on humans (asthma, allergies, headaches). Unfortunately, little is known about the environmental fate and toxicity of these substances. However, the use of alternative, predictive approaches, such as quantitative structure-activity relationships (QSARs), can help in filling the data gap and in the characterization of the environmental and toxicological profile of these substances. In the proposed study, ordinary least squares regression-based QSAR models were developed for three toxicological endpoints: mouse oral LD(50), inhibition of NADH-oxidase (EC(50) NADH-Ox) and the effect on mitochondrial membrane potential (EC(50) DeltaPsim). Theoretical molecular descriptors were calculated by using DRAGON software, and the best QSAR models were developed according to the principles defined by the Organization for Economic Co-operation and Development.

  18. Using Online Tool (iPrior) for Modeling ToxCast™ Assays Towards Prioritization of Animal Toxicity Testing.

    PubMed

    Abdelaziz, Ahmed; Sushko, Yurii; Novotarskyi, Sergii; Körner, Robert; Brandmaier, Stefan; Tetko, Igor V

    2015-01-01

    The use of long-term animal studies for human and environmental toxicity estimation is more discouraged than ever before. Alternative models for toxicity prediction, including QSAR studies, are gaining more ground. A recent approach is to combine in vitro chemical profiling and in silico chemical descriptors with the knowledge about toxicity pathways to derive a unique signature for toxicity endpoints. In this study we investigate the ToxCast™ Phase I data regarding their ability to predict long-term animal toxicity. We investigated thousands of models constructed in an effort to predict 61 toxicity endpoints using multiple descriptor packages and hundreds of in vitro assays. We investigated the use of in vitro assays and biochemical pathways on model performance. We identified 10 toxicity endpoints where biologically derived descriptors from in vitro assays or pathway perturbations improved the model prediction ability. In vivo toxicity endpoints proved generally challenging to model. Few models were possible to readily model with a balanced accuracy (BA) above 0.7. We also constructed in silico models to predict the outcome of 144 in vitro assays. This showed better statistical metrics with 79 out of 144 assays having median balanced accuracy above 0.7. This suggests that the in vitro datasets have a better modelability than in vivo animal toxicities for the given datasets. Moreover, we published an online platform (http://iprior.ochem.eu) that automates large-scale model building and analysis.

  19. Simulation model finned water-air-coil withoutcondensation

    SciTech Connect

    Wetter, Michael

    1999-01-01

    A simple simulation model of a finned water-to- air coil without condensation is presented. The model belongs to a collection of simulation models that allows eficient computer simulation of heating, ventilation, and air-conditioning (HVAC) systems. The main emphasis of the models is short computation time and use of input data that are known in the design process of an HVAC system. The target of the models is to describe the behavior of HVAC components in the part load operation mode, which is becoming increasingly important for energy efficient HVAC systems. The models are intended to be used for yearly energy calculation or load calculation with time steps of about 10 minutes or larger. Short-time dynamic effects, which are of interest for different aspects of control performance, are neglected. The part load behavior of the coil is expressed in terms of the nominal condition and the dimensionless variation of the heat transfer with change of mass flow and temperature on the water side and the air side. The effectiveness- NTU relations are used to parametrize the convective heat transfer at nominal conditions and to compute the part load conditions. Geometrical data for the coil are not required, The calculation of the convective heat transfer coefficients at nominal conditions is based on the ratio of the air side heat transfer coefficients multiplied by the fin eficiency and divided by the water side heat transfer coefficient. In this approach, the only geometrical information required are the cross section areas, which are needed to calculate the~uid velocities. The formulas for estimating this ratio are presented. For simplicity the model ignores condensation. The model is static and uses only explicit equations. The explicit formulation ensures short computation time and numerical stability. This allows using the model with sophisticated engineering methods such as automatic system optimization. The paper fully outlines the algorithm description and its

  20. The air quality forecast in Beijing with Community Multi-scale Air Quality Modeling (CMAQ) System: model evaluation and improvement

    NASA Astrophysics Data System (ADS)

    Wu, Q.

    2013-12-01

    The MM5-SMOKE-CMAQ model system, which is developed by the United States Environmental Protection Agency(U.S. EPA) as the Models-3 system, has been used for the daily air quality forecast in the Beijing Municipal Environmental Monitoring Center(Beijing MEMC), as a part of the Ensemble Air Quality Forecast System for Beijing(EMS-Beijing) since the Olympic Games year 2008. In this study, we collect the daily forecast results of the CMAQ model in the whole year 2010 for the model evaluation. The results show that the model play a good model performance in most days but underestimate obviously in some air pollution episode. A typical air pollution episode from 11st - 20th January 2010 was chosen, which the air pollution index(API) of particulate matter (PM10) observed by Beijing MEMC reaches to 180 while the prediction of PM10-API is about 100. Taking in account all stations in Beijing, including urban and suburban stations, three numerical methods are used for model improvement: firstly, enhance the inner domain with 4km grids, the coverage from only Beijing to the area including its surrounding cities; secondly, update the Beijing stationary area emission inventory, from statistical county-level to village-town level, that would provide more detail spatial informance for area emissions; thirdly, add some industrial points emission in Beijing's surrounding cities, the latter two are both the improvement of emission. As the result, the peak of the nine national standard stations averaged PM10-API, which is simulated by CMAQ as daily hindcast PM10-API, reach to 160 and much near to the observation. The new results show better model performance, which the correlation coefficent is 0.93 in national standard stations average and 0.84 in all stations, the relative error is 15.7% in national standard stations averaged and 27% in all stations. The time series of 9 national standard in Beijing urban The scatter diagram of all stations in Beijing, the red is the forecast and

  1. Development and application of a multimetal multibiotic ligand model for assessing aquatic toxicity of metal mixtures.

    PubMed

    Santore, Robert C; Ryan, Adam C

    2015-04-01

    A multimetal, multiple binding site version of the biotic ligand model (mBLM) has been developed for predicting and explaining the bioavailability and toxicity of mixtures of metals to aquatic organisms. The mBLM was constructed by combining information from single-metal BLMs to preserve compatibility between the single-metal and multiple-metal approaches. The toxicities from individual metals were predicted by assuming additivity of the individual responses. Mixture toxicity was predicted based on both dissolved metal and mBLM-normalized bioavailable metal. Comparison of the 2 prediction methods indicates that metal mixtures frequently appear to have greater toxicity than an additive estimation of individual effects on a dissolved metal basis. However, on an mBLM-normalized basis, mixtures of metals appear to be additive or less than additive. This difference results from interactions between metals and ligands in solutions including natural organic matter, processes that are accounted for in the mBLM. As part of the mBLM approach, a technique for considering variability was developed to calculate confidence bounds (called response envelopes) around the central concentration-response relationship. Predictions using the mBLM and response envelope were compared with observed toxicity for a number of invertebrate and fish species. The results show that the mBLM is a useful tool for considering bioavailability when assessing the toxicity of metal mixtures.

  2. Long-range transport modeling of air pollution episodes.

    PubMed

    de Leeuw, F A; Leyssius, H J

    1989-02-01

    The air quality network in the Netherlands is based on a regular grid with an interstation distance of 30 to 40 km. In or close to source areas, a higher station density is realized. Atmospheric transport models form an intrinsic part of the air quality monitoring system. The models are constructed in such a way that only routinely available meteorological input data are needed. The models are applied for interpretation and generalization of the measurements in terms of contributions of source categories. In scenario studies, the potential effect of abatement strategies is explored. The output of the models consists of concentration and deposition fields of NOx, NO2, SO2, sulfate, and nitrate on the scale of the Netherlands or on the scale of northwestern Europe. In the present version the models are not directly suitable to estimate exposures to acidic aerosols; however, in combination with limited aerosol measurements, the model predictions can be used to provide information on the spatial and temporal distribution of acidic aerosols as needed for exposure assessment.

  3. 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.

  4. New models and molecular markers in evaluation of developmental toxicity

    SciTech Connect

    Huuskonen, Hannele . E-mail: hannele.huuskonen@sttv.fi

    2005-09-01

    Mammalian and non-mammalian embryos and embryonic stem cells may be used as models in mechanistic studies and in testing embryotoxicity of compounds. In addition to conventional culture methods, genetic modifications and use of molecular markers offer significant advantages in mechanistic studies as well as in developing new test methods for embryotoxicity. Zebrafish model has been used for a long time and at present several applications are available. It is an easy vertebral non-mammalian model, whose genome is largely known and several genetic modifications are easily constructed to study gene expression or knocked down genes. Fluorescent marker proteins can be used also in zebrafish to indicate gene activation in transgenic models. Chemical genetics approach has been developed using zebrafish model. This is a new approach to screen small molecules that regulate signaling pathways. Embryonic stem cells have been used in mechanistic studies and mouse embryonic stem cell test has been validated to study embryotoxicity in vitro. This method has been improved using quantitative measurements of molecular endpoints by real-time RT-PCR or fluorescent activated cell sorting methods (FACS). Methods facilitating differentiation to several different cell types are available. We have studied preimplantation mouse embryos as a possible model for in vitro testing. In this method, superovulated and in vivo fertilized preimplantation embryos were collected at morula stage and cultured up to blastocysts. The mouse preimplantation culture test was improved by quantitative gene expression measurement using two-step real-time RT-PCR methods. New endpoints improve the tests of in vitro embryotoxicity because subjective assessments are replaced by objective measurements. In addition, automation is possible and less time is needed for analysis. Thus, high throughput screening will come possible to test large numbers of compounds.

  5. Modeling of TCE and Toluene Toxicity to Pseudomonas putida F1

    NASA Astrophysics Data System (ADS)

    Singh, R.; Olson, M. S.

    2009-12-01

    Prediction of viable bacterial distribution with respect to contaminants is important for efficient bioremediation of contaminated ground-water aquifers, particularly those contaminated with residual NAPLs. While bacterial motility and chemotaxis may help situate bacteria close to high concentrations of contaminant thereby enhancing bioremediation, prolonged exposure to high concentrations of contaminates is toxic to contaminant-degrading bacteria. The purpose of this work is to model the toxicity of trichloroethylene and toluene to Pseudomonas putida F1. The Live/Dead® bacterial viability assay was used to determine the toxic effect of chemical contaminants on the viability of P. putida F1 in a sealed zero head-space experimental environment. Samples of bacterial suspensions were exposed to common ground-water pollutants, TCE and toluene, for different durations. Changes in live and dead cell populations were monitored over the course of experiments using fluorescence microscopy. Data obtained from these toxicity experiments were fit to simple linear and exponential bacterial decay models using non-linear regression to describe loss of bacterial viability. TCE toxicity to P. putida F1 was best described with an exponential decay model (Figure 1a), with a decay constant kTCE = 0.025 h-4.95 (r2 = 0.956). Toluene toxicity showed a marginally better fit to the linear decay model (Figure 1b) (r2 = 0.971), with a decay constant ktoluene = 0.204 h-1. Best-fit model parameters obtained for both TCE and toluene were used to predict bacterial viability in toxicity experiments with higher contaminant concentrations and matched well with experimental data. Results from this study can be used to predict bacterial accumulation and viability near NAPL sources, and thus may be helpful in improving bioremediation performance assessment of contaminated sites. Figure 1: Survival ratios (S = N/No) of P. putida F1 in TCE- (a) and toluene- (b) stressed samples (observed (

  6. Transboundary air pollution in Asia: Model development and policy implications

    NASA Astrophysics Data System (ADS)

    Holloway, Tracey

    2001-12-01

    This work investigates transboundary air pollution in Asia through atmospheric modeling and public policy analysis. As an example of models actively shaping environmental policy, the Convention on Long-Range Transboundary Air Pollution in Europe (LRTAP) is selected as a case study. The LRTAP Convention is the only mulit- lateral air pollution agreement to date, and results from the RAINS integrated assessment model were heavily used to calculate nationally differentiated emission ceilings. Atmospheric chemistry and transport are included in RAINS through the use of transfer coefficients (or ``source-receptor relationships'') relating pollutant transfer among European nations. Following past work with ATMOS to simulate sulfur species in Asia, here ATMOS is developed to include odd-nitrogen. Fitting with the linear structure of ATMOS and the emphasis on computational efficiency, a simplified chemical scheme developed for use in the NOAA Geophysical Fluid Dynamics Laboratory Global Chemical Transport Model (GFDL GCTM) is adopted. The method solves for the interconversions between NOx, HNO3, and PAN based on five reaction rates stored in look-up tables. ATMOS is used to calculate source-receptor relationships for Asia. Significant exchange of NOy occurs among China, North and South Korea, and Japan. On an annual average basis, China contributes 18% to Japan's total nitrate deposition, 46% to North Korea, and 26% to South Korea. Nitrate deposition is an important component of acidification (along with sulfate deposition), contributing 30-50% to the acid burden over most of Japan, and more than 50% to acid deposition in southeast Asia, where biomass burning emits high levels of NOx. In evaluating the policy-relevance of results from the ATMOS model, four factors are taken into account: the uncertainty and limitations of ATMOS, the environmental concerns facing Asia, the current status of the scientific community in relation to regional air pollution in the region, and

  7. Detecting toxic diatom blooms from ocean color and a regional ocean model

    NASA Astrophysics Data System (ADS)

    Anderson, Clarissa R.; Kudela, Raphael M.; Benitez-Nelson, Claudia; Sekula-Wood, Emily; Burrell, Christopher T.; Chao, Yi; Langlois, Gregg; Goodman, Jo; Siegel, David A.

    2011-02-01

    An apparent link between upwelling-related physical signatures, macronutrients, and toxic diatom blooms in the various “hotspots” throughout California has motivated attempts to forecast harmful algal blooms (HABs) as a function of select environmental variables. Empirical models for predicting toxic Pseudo-nitzschia blooms in one such region, the Santa Barbara Channel (SBC), are tested in a nowcast mode using predictions based on merging data from MODIS ocean color geophysical products and the Regional Ocean Modeling System (ROMS) applied to the Southern California Bight. Thresholds for each model generate event forecasts. Spatially-explicit, monthly HAB maps are compared to shipboard observations and California monitoring data, demonstrating that the models predict offshore events otherwise undetected by nearshore monitoring. The use of mechanistic hydrodynamic models in concert with empirical, biological models facilitates future process studies on the effects of coastal eutrophication and climate change on regional HAB dynamics.

  8. Time-based collision risk modeling for air traffic management

    NASA Astrophysics Data System (ADS)

    Bell, Alan E.

    Since the emergence of commercial aviation in the early part of last century, economic forces have driven a steadily increasing demand for air transportation. Increasing density of aircraft operating in a finite volume of airspace is accompanied by a corresponding increase in the risk of collision, and in response to a growing number of incidents and accidents involving collisions between aircraft, governments worldwide have developed air traffic control systems and procedures to mitigate this risk. The objective of any collision risk management system is to project conflicts and provide operators with sufficient opportunity to recognize potential collisions and take necessary actions to avoid them. It is therefore the assertion of this research that the currency of collision risk management is time. Future Air Traffic Management Systems are being designed around the foundational principle of four dimensional trajectory based operations, a method that replaces legacy first-come, first-served sequencing priorities with time-based reservations throughout the airspace system. This research will demonstrate that if aircraft are to be sequenced in four dimensions, they must also be separated in four dimensions. In order to separate aircraft in four dimensions, time must emerge as the primary tool by which air traffic is managed. A functional relationship exists between the time-based performance of aircraft, the interval between aircraft scheduled to cross some three dimensional point in space, and the risk of collision. This research models that relationship and presents two key findings. First, a method is developed by which the ability of an aircraft to meet a required time of arrival may be expressed as a robust standard for both industry and operations. Second, a method by which airspace system capacity may be increased while maintaining an acceptable level of collision risk is presented and demonstrated for the purpose of formulating recommendations for procedures

  9. Modeling cadmium and nickel toxicity to earthworms with the free ion approach.

    PubMed

    Qiu, Hao; Vijver, Martina G; van Gestel, Cornelis A M; He, Erkai; Peijnenburg, Willie J G M

    2014-02-01

    The use of the free ion approach to quantify the toxic effects of Cd and Ni to the earthworms Lumbricus rubellus and Aporrectodea longa exposed in soils of different types was explored. Median lethal concentration (LC50) of Cd (expressed as the total concentration in soil) varied by approximately 11-fold and 28-fold for L. rubellus and A. longa, respectively. For Ni, these values were 50-fold and 38-fold, respectively. For the 2 earthworm species, no significant influence of cations (H(+), Ca(2+), Mg(2+), K(+), and Na(+)) on Cd(2+) toxicity was observed, while Mg(2+) was found to significantly alleviate Ni(2+) toxicity. The free ion activity model, which is a special case of the free ion approach with no impact of cations, sufficiently described the variability in Cd(2+) toxicity across soils but failed in predicting Ni(2+) toxicity. The free ion approach, in which the protective effects of Mg(2+) were included, explained 89% and 84% of the variations in LC50{Ni(2+)} (expressed as free ion activity) for L. rubellus (log LC50{Ni(2+)} = 1.18log{Mg(2+)}-0.52) and A. longa (log LC50{Ni(2+)} = 0.51log{Mg(2+)}-2.16), respectively. Prediction error was within a factor of 2 for both Cd(2+) and Ni(2+) toxicity, indicating the applicability of the free ion approach for predicting toxicity of these 2 metals. Although extrapolation of the free ion approach across metals still needs more research efforts, this approach, as an alternative to the biotic ligand model, provides a feasible framework for site-specific risk assessment.

  10. Methodology for Modeling the Microbial Contamination of Air Filters

    PubMed Central

    Joe, Yun Haeng; Yoon, Ki Young; Hwang, Jungho

    2014-01-01

    In this paper, we propose a theoretical model to simulate microbial growth on contaminated air filters and entrainment of bioaerosols from the filters to an indoor environment. Air filter filtration and antimicrobial efficiencies, and effects of dust particles on these efficiencies, were evaluated. The number of bioaerosols downstream of the filter could be characterized according to three phases: initial, transitional, and stationary. In the initial phase, the number was determined by filtration efficiency, the concentration of dust particles entering the filter, and the flow rate. During the transitional phase, the number of bioaerosols gradually increased up to the stationary phase, at which point no further increase was observed. The antimicrobial efficiency and flow rate were the dominant parameters affecting the number of bioaerosols downstream of the filter in the transitional and stationary phase, respectively. It was found that the nutrient fraction of dust particles entering the filter caused a significant change in the number of bioaerosols in both the transitional and stationary phases. The proposed model would be a solution for predicting the air filter life cycle in terms of microbiological activity by simulating the microbial contamination of the filter. PMID:24523908

  11. Updraft Model for Development of Autonomous Soaring Uninhabited Air Vehicles

    NASA Technical Reports Server (NTRS)

    Allen, Michael J.

    2006-01-01

    Large birds and glider pilots commonly use updrafts caused by convection in the lower atmosphere to extend flight duration, increase cross-country speed, improve range, or simply to conserve energy. Uninhabited air vehicles may also have the ability to exploit updrafts to improve performance. An updraft model was developed at NASA Dryden Flight Research Center (Edwards, California) to investigate the use of convective lift for uninhabited air vehicles in desert regions. Balloon and surface measurements obtained at the National Oceanic and Atmospheric Administration Surface Radiation station (Desert Rock, Nevada) enabled the model development. The data were used to create a statistical representation of the convective velocity scale, w*, and the convective mixing-layer thickness, zi. These parameters were then used to determine updraft size, vertical velocity profile, spacing, and maximum height. This paper gives a complete description of the updraft model and its derivation. Computer code for running the model is also given in conjunction with a check case for model verification.

  12. Estimating Lightning NOx Emissions for Regional Air Quality Modeling

    NASA Astrophysics Data System (ADS)

    Holloway, T.; Scotty, E.; Harkey, M.

    2014-12-01

    Lightning emissions have long been recognized as an important source of nitrogen oxides (NOx) on a global scale, and an essential emission component for global atmospheric chemistry models. However, only in recent years have regional air quality models incorporated lightning NOx emissions into simulations. The growth in regional modeling of lightning emissions has been driven in part by comparisons with satellite-derived estimates of column NO2, especially from the Ozone Monitoring Instrument (OMI) aboard the Aura satellite. We present and evaluate a lightning inventory for the EPA Community Multiscale Air Quality (CMAQ) model. Our approach follows Koo et al. [2010] in the approach to spatially and temporally allocating a given total value based on cloud-top height and convective precipitation. However, we consider alternate total NOx emission values (which translate into alternate lightning emission factors) based on a review of the literature and performance evaluation against OMI NO2 for July 2007 conditions over the U.S. and parts of Canada and Mexico. The vertical distribution of lightning emissions follow a bimodal distribution from Allen et al. [2012] calculated over 27 vertical model layers. Total lightning NO emissions for July 2007 show the highest above-land emissions in Florida, southeastern Texas and southern Louisiana. Although agreement with OMI NO2 across the domain varied significantly depending on lightning NOx assumptions, agreement among the simulations at ground-based NO2 monitors from the EPA Air Quality System database showed no meaningful sensitivity to lightning NOx. Emissions are compared with prior studies, which find similar distribution patterns, but a wide range of calculated magnitudes.

  13. ONE ATMOSPHERE MODELING FOR AIR QUALITY: BUILDING PARTNERSHIPS THAT TRANSITION RESEARCH INTO APPLICATIONS

    EPA Science Inventory

    The Community Miultiscale Air Quality (CMAQ) modeling system is a "one atmosphere" chemical transport model that simulates the transport and fate of air pollutants from urban to continental scales and from daily to annual time intervals.

  14. ADDRESSING HUMAN EXPOSURES TO AIR POLLUT