The U.S. Environmental Protection Agency (EPA) has a mission and regulatory responsibility to protect human health and the environment. EPA's pursuit of that goal includes a variety of research activities involving human subjects, such as epidemiologic studies and surveys. Those research activities also involve studies of individuals who volunteer to be exposed to air pollutants intentionally in controlled laboratory settings so that measurements can be made of transient and reversible biomarker or physiologic responses to those exposures that can indicate pathways of toxicity and mechanisms of air-pollution responses. The results of those controlled human inhalation exposure (CHIE) studies, also referred to as human clinical studies or human challenge studies, are used to inform policy decisions and help establish or revise standards to protect public health and improve air quality. Controlled Human Inhalation-Exposure Studies at EPA addresses scientific issues and provides guidance on the conduct of CHIE studies. This report assesses the utility of CHIE studies to inform and reduce uncertainties in setting air-pollution standards to protect public health and assess whether continuation of such studies is warranted. It also evaluates the potential health risks to test subjects who participated in recent studies of air pollutants at EPA's clinical research facility.
Most people in the United States spend far more time indoors than outdoors. Yet, many air pollution regulations and risk assessments focus on outdoor air. These often overlook contact with harmful contaminants that may be at their most dangerous concentrations indoors. A new book from the National Research Council explores the need for strategies to address indoor and outdoor exposures and examines the methods and tools available for finding out where and when significant exposures occur. The volume includes: A conceptual framework and common terminology that investigators from different disciplines can use to make more accurate assessments of human exposure to airborne contaminants. An update of important developments in assessing exposure to airborne contaminants: ambient air sampling and physical chemical measurements, biological markers, questionnaires, time-activity diaries, and modeling. A series of examples of how exposure assessments have been applied-properly and improperly-to public health issues and how the committee's suggested framework can be brought into practice. This volume will provide important insights to improve risk assessment, risk management, pollution control, and regulatory programs.
The United States Navy has been concerned for some time with protecting its military and civilian personnel from reproductive and developmental hazards in the workplace. As part of its efforts to reduce or eliminate exposure of Naval personnel and their families to reproductive and developmental toxicants, the Navy requested that the National Research Council (NRC) recommend an approach that can be used to evaluate chemicals and physical agents for their potential to cause reproductive and developmental toxicity. The NRC assigned this project to the Committee on Toxicology, which convened the Subcommittee on Reproductive and Developmental Toxicology, to prepare this report. In this report, the subcommittee recommends an approach for evaluating agents for potential reproductive and developmental toxicity and demonstrates how that approach can be used by the Navy. This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the NRC's Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their review of this report: James Chen (National Center for Toxicological Research), George Daston (Procter and Gamble Company), Jerry Heindel (National Institute of Environmental Health Sciences), Grace Lemasters (University of Cincinnati), and John Young (National Center for Toxicological Research).
Toxicity testing in laboratory animals provides much of the information used by the Environmental Protection Agency (EPA) to assess the hazards and risks associated with exposure to environmental agents that might harm public health or the environment. The data are used to establish maximum acceptable concentrations of environmental agents in drinking water, set permissible limits of exposure of workers, define labeling requirements, establish tolerances for pesticides residues on food, and set other kinds of limits on the basis of risk assessment. Because the number of regulations that require toxicity testing is growing, EPA called for a comprehensive review of established and emerging toxicity-testing methods and strategies. This interim report reviews current toxicity-testing methods and strategies and near-term improvements in toxicity-testing approaches proposed by EPA and others. It identifies several recurring themes and questions in the various reports reviewed. The final report will present a long-range vision and strategic plan to advance the practices of toxicity testing and human health assessment of environmental contaminants.
The public depends on competent risk assessment from the federal government and the scientific community to grapple with the threat of pollution. When risk reports turn out to be overblown--or when risks are overlooked--public skepticism abounds. This comprehensive and readable book explores how the U.S. Environmental Protection Agency (EPA) can improve its risk assessment practices, with a focus on implementation of the 1990 Clean Air Act Amendments. With a wealth of detailed information, pertinent examples, and revealing analysis, the volume explores the "default option" and other basic concepts. It offers two views of EPA operations: The first examines how EPA currently assesses exposure to hazardous air pollutants, evaluates the toxicity of a substance, and characterizes the risk to the public. The second, more holistic, view explores how EPA can improve in several critical areas of risk assessment by focusing on cross-cutting themes and incorporating more scientific judgment. This comprehensive volume will be important to the EPA and other agencies, risk managers, environmental advocates, scientists, faculty, students, and concerned individuals.
In 2007, the National Research Council envisioned a new paradigm in which biologically important perturbations in key toxicity pathways would be evaluated with new methods in molecular biology, bioinformatics, computational toxicology, and a comprehensive array of in vitro tests based primarily on human biology. Although some considered the vision too optimistic with respect to the promise of the new science, no one can deny that a revolution in toxicity testing is under way. New approaches are being developed, and data are being generated. As a result, the U.S. Environmental Protection Agency (EPA) expects a large influx of data that will need to be evaluated. EPA also is faced with tens of thousands of chemicals on which toxicity information is incomplete and emerging chemicals and substances that will need risk assessment and possible regulation. Therefore, the agency asked the National Research Council to convene a symposium to stimulate discussion on the application of the new approaches and data in risk assessment. The symposium was held on May 11-13, 2009, in Washington, DC, and included presentations and discussion sessions on pathway-based approaches for hazard identification, applications of new approaches to mode-of-action analyses, the challenges to and opportunities for risk assessment in the changing paradigm, and future directions.
Biomonitoring—a method for measuring amounts of toxic chemicals in human tissues—is a valuable tool for studying potentially harmful environmental chemicals. Biomonitoring data have been used to confirm exposures to chemicals and validate public health policies. For example, population biomonitoring data showing high blood lead concentrations resulted in the U.S. Environmental Protection Agency's (EPA's) regulatory reduction of lead in gasoline; biomonitoring data confirmed a resultant drop in blood lead concentrations. Despite recent advances, the science needed to understand the implications of the biomonitoring data for human health is still in its nascent stages. Use of the data also raises communication and ethical challenges. In response to a congressional request, EPA asked the National Research Council to address those challenges in an independent study. Human Biomonitoring for Environmental Chemicals provides a framework for improving the use of biomonitoring data including developing and using biomarkers (measures of exposure), research to improve the interpretation of data, ways to communicate findings to the public, and a review of ethical issues.
The regulation of potentially hazardous substances has become a controversial issue. This volume evaluates past efforts to develop and use risk assessment guidelines, reviews the experience of regulatory agencies with different administrative arrangements for risk assessment, and evaluates various proposals to modify procedures. The book's conclusions and recommendations can be applied across the entire field of environmental health.
New National Ambient Air Quality Standards for airborne particles smaller than 2.5 micrometers, called PM2.5, were issued by the U.S. Environmental Protection Agency (EPA) amidst scientific uncertainty and controversy. In response to a request from Congress, Research Priorities for Airborne Particulate Matter, the first of four books in a series, offers a conceptual framework for an integrated national program of particulate-matter research, identifies the 10 most critical research needs linked to key policy-related scientific uncertainties, and describes the recommended timing and estimated costs of such research. The committee concludes that EPA should devote more resources to investigating the relationships between fixed-site outdoor monitoring data and actual human breathing-zone exposures to ambient particulate matter and to identifying the most biologically important constituents and characteristics of particulate matter through toxicological studies. The recommended research activities are critical to determining actual exposures of human subpopulations most susceptible to harm from the most hazardous constituents of particulate matter. Future research will be an investment in public health and a means to ensure that resources spent on control technology and regulatory compliance will have a reasonable probability of success.
The EPA commissioned The National Academies to provide advice on the vexing question of whether and, if so, under what circumstances EPA should accept and consider intentional human dosing studies conducted by companies or other sources outside the agency (so-called third parties) to gather evidence relating to the risks of a chemical or the conditions under which exposure to it could be judged safe. This report recommends that such studies be conducted and used for regulatory purposes only if all of several strict conditions are met, including the following: The study is necessary and scientifically valid, meaning that it addresses an important regulatory question that can't be answered with animal studies or nondosing human studies; The societal benefits of the study outweigh any anticipated risks to participants. At no time, even when benefits beyond improved regulation exist, can a human dosing study be justified that is anticipated to cause lasting harm to study participants; and All recognized ethical standards and procedures for protecting the interests of study participants are observed. In addition, EPA should establish a Human Studies Review Board (HSRB) to evaluate all human dosing studiesâ€"both at the beginning and upon completion of the experimentsâ€"if they are carried out with the intent of affecting the agency's policy-making.
In 1991, the Environmental Protection Agency (EPA) and the Agency for Toxic Substances and Disease Registry (ATSDR) asked the National Research Council (NRC) to provide technical guidance for establishing community emergency exposure levels for extremely hazardous substances (EHSs) pursuant to the Superfund Amendments and Reauthorization Act of 1986. As a result the NRC published Guidelines for Developing Community Emergency Exposure Levels for Hazardous Substances in 1993 and Standing Operating Procedures for Developing Acute Exposure Guideline Levels for Hazardous Substances in 2001; providing updated procedures, methods, and other guidelines used by the National Advisory Committee (NAC) on Acute Exposure Guideline Levels (AEGLs) for hazardous substances for assessing acute adverse health effects. Stemming from this report the NAC has developed AEGLs for at least 270 EHSs. There are currently three AEGLs: AEGL-1, AEGL-2, and AEGL-3. AEGL-1 is the airborne concentration of a substance above which it is predicted that the general population could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. These effects are not disabling and are transient and reversible once exposure is stopped. AEGL-2 is the airborne concentration (of a substance above which it is predicted that the general population could experience irreversible, long-lasting adverse health effects or an impaired ability to escape. AEGL-3 is the airborne concentration of a substance above which it is predicted that the general population could experience life threatening health effects or death. On April 22-24 2013, the NRC-established Committee on Acute Exposure Guideline Levels 2013 met to review AEGL documents approved by the NAC. The committee members were selected for their expertise in toxicology, medicine, industrial hygiene, biostatistics, and risk assessment. Twenty-second Interim Report of the Committee on Acute Exposure Guideline Levels presents a review of AEGLs for various chemicals including acrylonitrile, halogen fluorides, tellurium hexafluoride, and thionyl chloride.
Risk assessments are often used by the federal government to estimate the risk the public may face from such things as exposure to a chemical or the potential failure of an engineered structure, and they underlie many regulatory decisions. Last January, the White House Office of Management and Budget (OMB) issued a draft bulletin for all federal agencies, which included a new definition of risk assessment and proposed standards aimed at improving federal risk assessments. This National Research Council report, written at the request of OMB, evaluates the draft bulletin and supports its overall goals of improving the quality of risk assessments. However, the report concludes that the draft bulletin is "fundamentally flawed" from a scientific and technical standpoint and should be withdrawn. Problems include an overly broad definition of risk assessment in conflict with long-established concepts and practices, and an overly narrow definition of adverse health effects-one that considers only clinically apparent effects to be adverse, ignoring other biological changes that could lead to health effects. The report also criticizes the draft bulletin for focusing mainly on human health risk assessments while neglecting assessments of technology and engineered structures.
Advances in molecular biology and toxicology are paving the way for major improvements in the evaluation of the hazards posed by the large number of chemicals found at low levels in the environment. The National Research Council was asked by the U.S. Environmental Protection Agency to review the state of the science and create a far-reaching vision for the future of toxicity testing. The book finds that developing, improving, and validating new laboratory tools based on recent scientific advances could significantly improve our ability to understand the hazards and risks posed by chemicals. This new knowledge would lead to much more informed environmental regulations and dramatically reduce the need for animal testing because the new tests would be based on human cells and cell components. Substantial scientific efforts and resources will be required to leverage these new technologies to realize the vision, but the result will be a more efficient, informative and less costly system for assessing the hazards posed by industrial chemicals and pesticides.
Trichloroethylene (TCE) is a solvent that is used as a degreasing agent, a chemical intermediate in refrigerant manufacture, and a component of spot removers and adhesives. It is produced in mass quantities but creates dangerous vapors and is an environmental contaminant at many industrial and government facilities, including facilities run by the U.S. Department of Defense (DoD). It is important to determine the safe occupational exposure level (OEL) for the solvent in order to protect the health of workers who are exposed to its vapors. However, there are concerns that the current occupational standards insufficiently protect workers from these health threats. Review of DOD's Approach to Deriving an Occupational Exposure Level for Trichloroethylene makes recommendations to improve the DoD's approach to developing an OEL for TCE, strengthen transparency of the process, and improve confidence in the final OEL value. This report reviews the DoD's approach using a literature review, evidence synthesis based on weight of evidence [WOE], point-of-departure derivation, physiologically based pharmacokinetic modeling, extrapolation tools, and explores other elements of the process of deriving an OEL for TCE. It examines scientific approaches to developing exposure values and cancer risk levels, defining the scope of the problem, and improving hazard identification.
A large number of chemicals are used on land at shore facilities, in the air in combat and reconnaissance aircraft, on seas around the world in surface vessels, and in submarine vessels by the navy and marine corps. Although the chemicals used are for the large part harmless, there is a significant amount of chemicals in use that can be health hazards during specific exposure circumstances. The Navy Environmental Health Center (NEHC) is primarily tasked with assessing these hazards. The NEHC completes its tasks by reviewing toxicological and related data and preparing health-hazard assessments (HHAs) for the different chemicals. Since the NEHC is continually asked to develop these HHAs, the National Research Council (NRC) was asked to assess independently the validity and effectiveness of NEHC's HHA process, in order to determine whether the process as implemented provides the Navy with the best, comprehensive, and defensible evaluations of health hazards and to identify any elements that might require improvement. The task was assigned to the Board on Environmental Studies and Toxicology's Committee on Toxicology's (COT's) Subcommittee on Toxicological hazard and Risk Assessment. Review of the U.S. Navy Environmental Health Center's Health-Hazard Assessment Process presents the subcommittee's report. The report is the work of expertise in general toxicology, inhalation toxicology, epidemiology, neurotoxicology, immunotoxicology, reproductive and developmental toxicology, pharmacology, medicine, risk assessment, and biostatistics. It is based on its review of documents provided by NEHC, presentations by NEHC personnel, and site visits to NEHC in Norfolk, Virginia and an aircraft carrier in San Diego, California.
The National Human Monitoring Program (NHMP) identifies concentrations of specific chemicals in human tissues, including toxicologic testing and risk assessment determinations. This volume evaluates the current activities of the NHMP; identifies important scientific, technical, and programmatic issues; and makes recommendations regarding the design of the program and use of its products.
The U.S. Environmental Protection Agency (EPA) has a mission and regulatory responsibility to protect human health and the environment. EPA's pursuit of that goal includes a variety of research activities involving human subjects, such as epidemiologic studies and surveys. Those research activities also involve studies of individuals who volunteer to be exposed to air pollutants intentionally in controlled laboratory settings so that measurements can be made of transient and reversible biomarker or physiologic responses to those exposures that can indicate pathways of toxicity and mechanisms of air-pollution responses. The results of those controlled human inhalation exposure (CHIE) studies, also referred to as human clinical studies or human challenge studies, are used to inform policy decisions and help establish or revise standards to protect public health and improve air quality. Controlled Human Inhalation-Exposure Studies at EPA addresses scientific issues and provides guidance on the conduct of CHIE studies. This report assesses the utility of CHIE studies to inform and reduce uncertainties in setting air-pollution standards to protect public health and assess whether continuation of such studies is warranted. It also evaluates the potential health risks to test subjects who participated in recent studies of air pollutants at EPA's clinical research facility.
In 1993, the National Research Council's Committee on Toxicology developed criteria and methods for EPA and the Agency for Toxic Substances and Disease Registry (ATSDR) to develop community emergency exposure levels for extremely hazardous substances for the general population. A few years later, the National Advisory Committee for Acute Exposure Guideline Levels for Hazardous Substances (NAC)â€"composed of members of EPA, DOD, other federal and state agencies, industry, academia, and other organizationsâ€"was established to identify, review, and interpret toxicologic and other scientific data to develop acute exposure guidelines (AEGLs) for high-priority, acutely toxic chemicals. Three levelsâ€"AEGL-1, AEGL-2, and AEGL-3 are developed for each of five exposure periods (10 min, 30 min, 1 hr, 4 hr, and 8 hr) and are distinguished by varying degrees of severity of toxic effects. This current report reviews the NAC reports for their scientific validity, completeness, and consistency with the NRC guideline reports developed in 1993 and 2001. This report is the fifth volume in the series and covers AEGLs for chlorine dioxide, chlorine trifluoride, cyclohexylamine, ethylenediamine, hydrofluoroether-7100, and tetranitromethane. It concludes that the AEGLs developed by NAC are scientifically valid and consistent with the NRC guideline reports. AEGLs are needed for a wide range of planning, response, and prevention applications. These values provide data critical to evacuation decisions and discussions between community leaders and industries as they seek ways to minimize the health impact should the chemical release occur. Some of the finalized AEGLs have been officially adopted by the Department of the Army, FEMA, and the Department of Transportation as the official levels for use by those agencies.
Standing Operating Procedures for Developing Acute Exposure Guideline Levels for Hazardous Chemicals contains a detailed and comprehensive methodology for developing acute exposure guideline levels (AEGLs) for toxic substances from inhalation exposures. The book provides guidance on what documents and databases to use, toxicity endpoints that need to be evaluated, dosimetry corrections from animal to human exposures, selection of appropriate uncertainty factors to address the variability between animals and humans and within the human population, selection of modifying factors to address data deficiencies, time scaling, and quantitative cancer risk assessment. It also contains an example of a summary of a technical support document and an example of AEGL derivation. This book will be useful to persons in the derivation of levels from other exposure routesâ€"both oral and dermalâ€"as well as risk assessors in the government, academe, and private industry.
Scientific Frontiers in Developmental Toxicology and Risk Assessment reviews advances made during the last 10-15 years in fields such as developmental biology, molecular biology, and genetics. It describes a novel approach for how these advances might be used in combination with existing methodologies to further the understanding of mechanisms of developmental toxicity, to improve the assessment of chemicals for their ability to cause developmental toxicity, and to improve risk assessment for developmental defects. For example, based on the recent advances, even the smallest, simplest laboratory animals such as the fruit fly, roundworm, and zebrafish might be able to serve as developmental toxicological models for human biological systems. Use of such organisms might allow for rapid and inexpensive testing of large numbers of chemicals for their potential to cause developmental toxicity; presently, there are little or no developmental toxicity data available for the majority of natural and manufactured chemicals in use. This new approach to developmental toxicology and risk assessment will require simultaneous research on several fronts by experts from multiple scientific disciplines, including developmental toxicologists, developmental biologists, geneticists, epidemiologists, and biostatisticians.
The Bhopal Disaster of 1984 resulted in the death of around 2,000 residents living near chemical plants and irreversible injuries to more than 20,000 other residents. These numbers can be attributed to the community's lack of awareness concerning the chemicals' existence, dangers and effects, and/or how to react in case of emergency. The disaster emphasized the need for governments to identify hazardous substances and to aid local communities in developing plans for emergency exposures. As a result, the United States government issued the Superfund Amendments and Reauthorization Act (SARA) of 1986; requiring the identification of extremely hazardous substances (EHSs) by the Environmental Protection Agency (EPA). EPA was also tasked with assisting Local Emergency Planning Committees (LEPCs) in conducting health-hazard assessments to develop emergency-response plans for sites where EHSs are produced, stored, transported, or used. The EPA identified nearly 400 EHSs in terms of their immediate danger to life and health (IDLH) as their first step in assisting these LEPCs. In 1991 the EPA went on to request that the National Research Council (NRC) Committee on Toxicology (COT) develop criteria and methods for developing emergency exposure levels for EHSs for the general population. The COT, who had published many reports on emergency exposure guidance levels at the time, designated the task to a subcommittee. The subcommittee focused on Guidelines for Developing Community Emergency Exposure Levels for Hazardous Substances. Four years later the National Advisory Committee for Acute Exposure Guideline Levels for Hazardous Substances (NAC) was created with a focus on identifying, reviewing, and interpreting relevant toxicologic and other scientific data and developing acute exposure guideline levels (AEGLs) for high-priority, acutely toxic chemicals. In Acute Exposure Guideline Levels for Selected Airborne Chemicals:Volume 4, the NAC outlines acute exposure guideline levels for chlorine, hydrogen chloride, toluene 2,4, hydrogen fluoride, 2,6-diisocyanate, and uranium hexafluoride.
Extremely hazardous substances (EHSs) can be released accidentally as a result of result of chemical spills, industrial explosions, fires, or accidents involving railroad cars and trucks transporting EHSs. Workers and residents in communities surrounding industrial facilities where EHSs are manufactured, used, or stored and in communities along the nation's railways and highways are potentially at risk of being exposed to airborne EHSs during accidental releases or intentional releases by terrorists. Pursuant to the Superfund Amendments and Reauthorization Act of 1986, the U.S. Environmental Protection Agency (EPA) has identified approximately 400 EHSs on the basis of acute lethality data in rodents. As part of its efforts to develop acute exposure guideline levels for EHSs, EPA and the Agency for Toxic Substances and Disease Registry (ATSDR) in 1991 requested that the National Research Council (NRC) develop guidelines for establishing such levels. In response to that request, the NRC published Guidelines for Developing Community Emergency Exposure Levels for Hazardous Substances in 1993. Subsequently, Standard Operating Procedures for Developing Acute Exposure Guideline Levels for Hazardous Substances was published in 2001, providing updated procedures, methodologies, and other guidelines used by the National Advisory Committee (NAC) on Acute Exposure Guideline Levels for Hazardous Substances and the Committee on Acute Exposure Guideline Levels (AEGLs) in developing the AEGL values. Using the 1993 and 2001 NRC guidelines reports, the NAC-consisting of members from EPA, the Department of Defense (DOD), the Department of Energy (DOE), the Department of Transportation (DOT), other federal and state governments, the chemical industry, academia, and other organizations from the private sector-has developed AEGLs for more than 270 EHSs. In 1998, EPA and DOD requested that the NRC independently review the AEGLs developed by NAC. In response to that request, the NRC organized within its Committee on Toxicology (COT) the Committee on Acute Exposure Guideline Levels, which prepared this report. This report is the fourteenth volume in that series. Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 14 summarizes the committee's conclusions and recommendations.
In the Bhopal disaster of 1984, approximately 2,000 residents living near a chemical plant were killed and 20,000 more suffered irreversible damage to their eyes and lungs following the accidental release of methyl isocyanate. This tragedy served to focus international attention on the need for governments to identify hazardous substances and assist local communities in planning how to deal with emergency exposures. Since 1986, the U.S. Environmental Protection Agency has been tasked with identifying extremely hazardous substances and, in cooperation with the Federal Emergency Management Agency and the Department of Transportation, assist local emergency response planners. The National Advisory Committee on Acute Exposure Guideline Levels for Hazardous Substances was established in 1995 to develop acute exposure guideline levels (AEGLs) for high priority toxic chemicals that could be released into the air from accidents at chemical plants, storage sites, or during transportation. This book reviews toxicity documents on five chemicalsâ€"chlorine, hydrogen chloride, hydrogen fluoride, toluene, and uranium hexafluorideâ€"for their scientific validity, comprehensives, internal consistency, and conformance to the 1993 guidelines report.
In 1991, the Environmental Protection Agency (EPA) and the Agency for Toxic Substances and Disease Registry (ATSDR) asked the National Research Council (NRC) to provide technical guidance for establishing community emergency exposure levels for extremely hazardous substances (EHSs) pursuant to the Superfund Amendments and Reauthorization Act of 1986. In response to that request, the NRC published Guidelines for Developing Community Emergency Exposure Levels for Hazardous Substances in 1993. Subsequently, Standing Operating Procedures for Developing Acute Exposure Guideline Levels for Hazardous Substances was published in 2001; it provided updated procedures, methods, and other guidelines used by the National Advisory Committee (NAC) on Acute Exposure Guideline Levels (AEGLs) for hazardous substances for assessing acute adverse health effects. Using both these reports, the NAC-consisting of members from the EPA, the Department of Defense (DOD), the Department of Energy (DOE), the Department of Transportation (DOT), other federal and state governments, the chemical industry, academia, and other organizations from the private sector-developed AEGLs for approximately 270 EHSs. In 1998, EPA and DOD requested that the NRC independently review the AEGLs developed by NAC. In response to that request, the NRC organized within its Committee on Toxicology the Committee on Acute Exposure Guideline Levels, which prepared this report. This report, Twenty-First Interim Report of the Committee on Acute Exposure Guideline Levels: Part B, summarizes the committee's conclusions and recommendations for improving AEGL documents for several chemicals and chemical classes not mentioned in Twenty-First Interim Report of the Committee on Acute Exposure Guideline Levels: Part A.
Manufactured vitreous fibers (MVF), also known as synthetic vitreous fibers, are considered to be less hazardous than asbestos to human health. They are used in many thermal- and acoustical-insulation applications as an asbestos substitute or as a filtration medium. The Navy uses MVF in shipboard and onshore applications. To protect Navy personnel from harmful exposures to MVF, the U.S. Navy Environmental Health Center (NEHC) developed occupational exposure standards. The documentation assists industrial hygienists, occupational medicine physicians, and other Navy health professionals in assessing and controlling the health hazards linked with exposure to MVF. In 1997, the National Research Council (NRC) was asked to conduct an independent review of the Navy's toxicological assessment of MVF and to evaluate the scientific validity of its exposure standard of 2 fibers per cubic centimeter of air (f/cm3). The NRC assigned the task to the Committee on Toxicology, which established the Subcommittee on Manufactured Vitreous Fibers, a multidisciplinary group of experts, to determine whether all relevant toxicological and epidemiological data were correctly considered in developing the exposure standard; and to examine the uncertainty, variability, and quality of data and the appropriateness of assumptions used in the derivation of the exposure standard. The subcommittee was also asked to identify deficiencies in the MVF database and, where appropriate, to make recommendations for future research and data development. Review of the U.S. Navy's exposure Standard for Manufactured Vitreous Fibers represents the subcommittee's final report. The committee had expanded its review when in January 1999, the Navy revised its Occupational Safety and Health Program Manual (CNO 1999), changing the occupational exposure limit for MVF to the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 1 f/cm3. The report features recommendations by the subcommittee as well as information gaps found throughout investigation. Overall, the subcommittee found that the Navy made a good start in assessing the health effects of MVF, but needed further research.
Fort Detrick's Area B has been used for disposal of chemical, biological, and radiological material, storage of explosives, and research activities. The groundwater of Area B was contaminated by perchloroethylene (PCE) and trichloroethylene (TCE), which leaked from storage drums buried in Area B. Members of the public who live near Fort Detrick in Frederick County, Maryland, are concerned that the contaminated groundwater might have affected their health. This report reviews two investigations of potential health hazards: a 2009 public health assessment conducted by the Agency for Toxic Substances and Disease Registry and a cancer investigation in Frederick County by the Maryland Department of Health and Mental Hygiene and the Frederick County Health Department.
Acute Exposure Guideline Levels for Selected Airborne Chemicals, Volume 15 identifies, reviews, and interprets relevant toxicologic and other scientific data for ethyl mercaptan, methyl mercaptan, phenyl mercaptan, tert-octyl mercaptan, lewisite, methyl isothiocyanate, and selected monoisocyanates in order to develop acute exposure guideline levels (AEGLs) for these high-priority, acutely toxic chemicals. AEGLs represent threshold exposure limits (exposure levels below which adverse health effects are not likely to occur) for the general public and are applicable to emergency exposures ranging from 10 minutes (min) to 8 h. Three level--AEGL-1, AEGL-2, and AEGL-3--are developed for each of five exposure periods (10 min, 30 min, 1 h, 4 h, and 8 h) and are distinguished by varying degrees of severity of toxic effects. This report will inform planning, response, and prevention in the community, the workplace, transportation, the military, and the remediation of Superfund sites.
Extremely hazardous substances can be released accidentally as a result of chemical spills, industrial explosions, fires, or accidents involving railroad cars and trucks transporting EHSs. Workers and residents in communities surrounding industrial facilities where these substances are manufactured, used, or stored and in communities along the nation's railways and highways are potentially at risk of being exposed to airborne EHSs during accidental releases or intentional releases by terrorists. Pursuant to the Superfund Amendments and Reauthorization Act of 1986, the U.S. Environmental Protection Agency (EPA) has identified approximately 400 EHSs on the basis of acute lethality data in rodents. Acute Exposure Guideline Levels for Selected Airborne Chemicals, Volume 17 identifies, reviews, and interprets relevant toxicologic and other scientific data for selected AEGL documents for acrylonitrile, carbon tetrachloride, cyanogen, epichlorohydrin, ethylene chlorohydrin, toluene, trimethylacetyl chloride, hydrogen bromide, and boron tribromide in order to develop acute exposure guideline levels (AEGLs) for these high-priority, acutely toxic chemicals. AEGLs represent threshold exposure limits (exposure levels below which adverse health effects are not likely to occur) for the general public and are applicable to emergency exposures ranging from 10 minutes (min) to 8 h. Three levels - AEGL-1, AEGL-2, and AEGL-3 - are developed for each of five exposure periods (10 min, 30 min, 1 h, 4 h, and 8 h) and are distinguished by varying degrees of severity of toxic effects. This report will inform planning, response, and prevention in the community, the workplace, transportation, the military, and the remediation of Superfund sites.
Extremely hazardous substances can be released accidentally as a result of chemical spills, industrial explosions, fires, or accidents involving railroad cars and trucks transporting EHSs. Workers and residents in communities surrounding industrial facilities where these substances are manufactured, used, or stored and in communities along the nation's railways and highways are potentially at risk of being exposed to airborne EHSs during accidental releases or intentional releases by terrorists. Pursuant to the Superfund Amendments and Reauthorization Act of 1986, the U.S. Environmental Protection Agency (EPA) has identified approximately 400 EHSs on the basis of acute lethality data in rodents. Acute Exposure Guideline Levels for Selected Airborne Chemicals, Volume 19 identifies, reviews, and interprets relevant toxicologic and other scientific data for selected AEGL documents for cyanide salts, diketene, methacrylaldehyde, pentaborane, tellurium hexafluoride, and tetrafluoroethylene in order to develop acute exposure guideline levels (AEGLs) for these high-priority, acutely toxic chemicals. AEGLs represent threshold exposure limits (exposure levels below which adverse health effects are not likely to occur) for the general public and are applicable to emergency exposures ranging from 10 minutes (min) to 8 h. Three levels - AEGL-1, AEGL-2, and AEGL-3 - are developed for each of five exposure periods (10 min, 30 min, 1 h, 4 h, and 8 h) and are distinguished by varying degrees of severity of toxic effects. This report will inform planning, response, and prevention in the community, the workplace, transportation, the military, and the remediation of Superfund sites.
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