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PubMed1983

An overview of current efforts in short-term carcinogen testing.

Scientists in the Health and Environmental Review Division (HERD), Office of Toxic Substances of the U.S. Environmental Protection Agency, are examining the feasibility of expanding efforts in short-term carcinogen testing. Three areas for consideration have been defined. These are (1) short-term in vitro tests; (2) short-term in vivo tests; and (3) tumor markers. HERD's current efforts in short-term in vitro testing are exemplified by the Gene-Tox program. Through a comprehensive system of committees and reviews, the published literature on eukaryotic and prokaryotic in vitro and in vivo test systems are being examined and analyzed. The suitability of utilizing the various systems in a test battery to identify potential chemical mutagens and carcinogens will be ascertained. A review of the literature on short-term in vivo tests (limited bioassays) and tumor markers is currently being conducted. Correlations will be made between results obtained from these tests and epidemiological information and long-term animal bioassays. The attributes and deficiencies of each test or marker will be examined. Further testing, development, or validation needs will be outlined. The aim of this review is to attempt to expand the prechronic test battery for carcinogenicity in order to provide sufficient information for regulatory decision-making.

Biological Assay↗
PubMedDate not supplied

Validation of a terrestrial food chain model.

An increasingly important topic in risk assessment is the estimation of human exposure to environmental pollutants through pathways other than inhalation. The Environmental Protection Agency (EPA) has recently developed a computerized methodology (EPA, 1990) to estimate indirect exposure to toxic pollutants from Municipal Waste Combuster emissions. This methodology estimates health risks from exposure to toxic pollutants from the terrestrial food chain (TFC), soil ingestion, drinking water ingestion, fish ingestion, and dermal absorption via soil and water. Of these, one of the most difficult to estimate is exposure through the food chain. This paper estimates the accuracy of the EPA methodology for estimating food chain contamination. To our knowledge, no data exist on measured concentrations of pollutants in food grown around Municipal Waste Incinerators, and few field-scale studies have been performed on the uptake of pollutants in the food chain. Therefore, to evaluate the EPA methodology, we compare actual measurements of background contaminant levels in food with estimates made using EPA's computerized methodology. Background levels of contaminants in air, water, and soil were used as input to the EPA food chain model to predict background levels of contaminants in food. These predicted values were then compared with the measured background contaminant levels. Comparisons were performed for dioxin, pentachlorophenol, polychlorinated biphenyls, benzene, benzo(a)pyrene, mercury, and lead.

Air Pollutants↗
PubMed2004

An unrecognized source of PCB contamination in schools and other buildings.

An investigation of 24 buildings in the Greater Boston Area revealed that one-third (8 of 24) contained caulking materials with polychlorinated biphenyl (PCB) content exceeding 50 ppm by weight, which is the U.S. Environmental Protection Agency (U.S. EPA) specified limit above which this material is considered to be PCB bulk product waste. These buildings included schools and other public buildings. In a university building where similar levels of PCB were found in caulking material, PCB levels in indoor air ranged from 111 to 393 ng/m3; and in dust taken from the building ventilation system, < 1 ppm to 81 ppm. In this building, the U.S. EPA mandated requirements for the removal and disposal of the PCB bulk product waste as well as for confirmatory sampling to ensure that the interior and exterior of the building were decontaminated. Although U.S. EPA regulations under the Toxic Substances Control Act stipulate procedures by which PCB-contaminated materials must be handled and disposed, the regulations apparently do not require that materials such as caulking be tested to determine its PCB content. This limited investigation strongly suggests that were this testing done, many buildings would be found to contain high levels of PCBs in the building materials and potentially in the building environment. The presence of PCBs in schools is of particular concern given evidence suggesting that PCBs are developmental toxins.

Boston↗
PubMed2006

Incorporating sediment stability within the management of contaminated sediment sites: a synthesis approach.

At the Third International Conference on Remediation of Contaminated Sediments, a panel discussion was held to consider how best to incorporate sediment stability assessment (SSA) results when managing risks at contaminated sediment sites. This remains a challenge to the scientific and regulatory community, especially at sites where large volumes of legacy sediment are present below layers of recent sediment of better quality, and where in-place management may be viable. Use of a suite of empirical and predictive approaches collectively to assess potential risks resulting from bed erosion has emerged as the state-of-the-art approach for SSA, yet current practice lacks consistent guidance for conducting such assessments and for dealing with and communicating implications of uncertainty. The regulatory community lacks a decision-making framework that specifically incorporates SSA results, though it is a consideration in US Environmental Protection Agency (USEPA 2002) Principles for Sediment Management. Practitioners have not consistently communicated SSA results from a risk perspective to the stakeholder community. We believe this combination of factors, especially the inconsistent framing of results in a risk context, has contributed to discounted use of sediment stability information in decision making, fostering application of the precautionary principle, where removal is viewed as a presumed conservative but more expensive approach over in-place management options. We assert that the incorporation of SSA in decision making will be improved through the use of a consistent SSA assessment framework built around the conceptual site model, incorporating multiple lines of evidence detailing the potential impacts of large, low-probability events (e.g., the 100-y storm) on exposure and risk, and the associated uncertainties. Further advocacy of this approach was realized through panel-audience discussion at the conference. The technical methods discussed are not new; rather, it is the synthesis approach emphasized here, which by providing a framework for the systematic evaluation of how SSA is best addressed from site to site, makes the results of SSA efforts more accessible and acceptable to stakeholders and decision makers.

Conservation of Natural Resources↗
PubMed2006

Quantitative vapor-phase infrared spectrometry of ammonia.

Reference spectra of ammonia from four sources are compared. Low-resolution spectra (i.e., spectra for which the spectrometer resolution is numerically greater than the full-width at half-height of the rotational lines) were obtained from the Environmental Protection Agency (EPA) web site and from Infrared Analysis, Inc. High-resolution (0.12 cm-1) spectra were obtained from the National Institute for Standards and Technology (NIST) and Pacific Northwest National Laboratory (PNNL). Two protocols were used to validate the EPA and Infrared Analysis spectra, with one requiring that Beer's law be obeyed by the low-resolution spectrum and the other that Beer's law be obeyed by the high-resolution spectrum. In all cases, the second protocol gave a significantly better spectral match. It is shown that the path-integrated concentrations for the low-resolution reference spectra were in error by as little as 4% to as much as an order of magnitude, presumably because of the effect of adsorption on the cell walls. Measured absorptivities of the NIST and PNNL spectra were different by approximately 2.6% and it is believed that the effect of adsorption on these spectra is small. When the same protocols were used to test the reference spectrum of methane, the calculated path-integrated concentration was only approximately 2% different from the one that was calculated from the NIST reference spectrum, suggesting that the data processing protocols provide accurate data.

Ammonia↗
PubMed1992

Regulation of existing chemicals under TSCA: information disclosure as the route to reducing risk and increasing available data.

The Toxic Substances Control Act (TSCA) empowers the Environmental Protection Agency (EPA) to regulate risk associated with the use of existing chemicals and the introduction of new chemicals into commerce. Due to a number of concerns, however, the authority to regulate existing chemicals under TSCA has enjoyed limited success. A more generic and flexible approach is needed to achieve significant risk reduction for existing chemicals. This paper presents a frame-work for a generic approach to the regulation of existing chemicals. Under this framework, EPA would officially recognize that the distribution of chemical substances without evaluating and communicating to the user how to avoid operationally undesirable exposures represents an unreasonable risk to health or the environment. Acting under the authority of TSCA, EPA would then generically require suppliers to communicate acceptable exposure levels and information regarding safe use. This framework is consistent with the express policy of TSCA, which states that development of data with respect to the effects of chemical substances and mixtures on health and the environment should be the responsibility of manufacturers and processors of chemicals. The approach outlined here is consistent with and complements initiatives of the Office of Toxic Substances (OTS) and would enable OTS to accomplish some of the fundamental goals of TSCA.

Chemical Industry↗
PubMed2002

Estimating the human health risks from polychlorinated dioxins and furans in stack gas emissions from combustion units: implications of USEPA's dioxin reassessment.

Shortly after promulgation of the Hazardous Waste Combustor MACT rule established regulatory limits for polychlorinated dioxins and furans (dioxins/furans) in incinerator stack gas, the US Environmental Protection Agency (USEPA) announced that facilities could still be required to demonstrate that stack emissions do not present an unacceptable risk to human health and the environment. Guidance for conducting this risk assessment activity, which was to be required under RCRA omnibus authority, was developed by the agency and released in 1998. The guidance represented an increase in complexity over previous documents developed by the agency and contains multiple chemical, fate and transport, and toxicological parameters which are to be used as default deterministic parameters in a complex series of algorithms which ultimately lead to numerical estimates of risk. As these changes were occurring, USEPA was also moving towards completion of its reassessment of dioxin. That series of documents has been the subject of considerable controversy and has, in several of its various drafts, proposed a number of changes, including modification of the existing toxic equivalency factor (TEF) approach and of the cancer potency factor of 2,3,7,8-tetachlorodibenzo-p-dioxin. At this time it is unclear what the impact of these changes will be on facilities progressing through the permitting process, because it is not intuitively obvious how changes in the risk assessment input parameters will impact the magnitude of the dioxinlfuran risk. In this paper, the receptor usually associated with the highest potential risk from dioxins/furans in a combustion risk assessment, the Subsistence Farmer, will be subjected to a sensitivity analysis to determine which of the multiple default input parameters will have the greatest influence on the potential cancer risk.

Algorithms↗
PubMedDate not supplied

Recent advances in the estimation of population exposure to mobile source pollutants.

The U.S. Environmental Protection Agency (EPA) has developed several computer-based exposure models applicable to pollutants which are directly or indirectly linked to mobile sources. Probabilistic versions of the National Ambient Air Quality Standards (NAAQS) Exposure Model (pNEM) have been used to estimate the exposures of urban populations to carbon monoxide and ozone. An enhanced version of the Hazardous Air Pollutant Exposure Model (HAPEM-MS) has been used to develop city-specific estimates of exposure to benzene and other volatile organic compounds emitted by mobile sources. These models are similar in that each contains algorithms that simulate microenvironmental pollutant levels, time/activity patterns, and commuting patterns. The pNEM models also provide estimates of equivalent ventilation rate (EVR), defined as ventilation rate divided by body surface area. This paper summarizes the methods and results of selected research projects conducted since 1991 with the goal of improving pNEM, HAPEM-MS, and similar exposure models applicable to mobile source pollutants. The studies include: (1) the development of an improved algorithm for estimating EVR, (2) a field study to measure ozone levels near roadways and inside vehicles, (3) the development of an algorithm for estimating school commuting patterns, and (4) the construction of a comprehensive database containing time/activity data from ten activity diary studies.

Adult↗
PubMed1999

Estimating risk assessment exposure point concentrations when the data are not normal or lognormal.

The U.S. Environmental Protection Agency (EPA) recommends the use of the one-sided 95% upper confidence limit of the arithmetic mean based on either a normal or lognormal distribution for the contaminant (or exposure point) concentration term in the Superfund risk assessment process. When the data are not normal or lognormal this recommended approach may overestimate the exposure point concentration (EPC) and may lead to unecessary cleanup at a hazardous waste site. The EPA concentration term only seems to perform like alternative EPC methods when the data are well fit by a lognormal distribution. Several alternative methods for calculating the EPC are investigated and compared using soil data collected from three hazardous waste sites in Montana, Utah, and Colorado. For data sets that are well fit by a lognormal distribution, values for the Chebychev inequality or the EPA concentration term may be appropriate EPCs. For data sets where the soil concentration data are well fit by gamma distributions, Wong's method may be used for calculating EPCs. The studentized bootstrap-t and Hall's bootstrap-t transformation are recommended for EPC calculation when all distribution fits are poor. If a data set is well fit by a distribution, parametric bootstrap may provide a suitable EPC.

Evaluation Studies as Topic↗
PubMed1992

The role of threshold limit values in U.S. air pollution policy.

This paper analyzes the role of threshold limit values (TLVs) in national air pollution policy during the 1980s, a period in which the Environmental Protection Agency (EPA) sought to delegate to individual states the authority to evaluate and regulate airborne toxic substances. We focus on 20 carcinogens and 11 substances with non-genotoxic health effects that were regulated by local air toxics programs using TLVs. Data from EPA's National Air Toxics Information Clearinghouse indicate that maximum TLV-based Ambient Air Level guidelines (AALs) frequently exceed minimum TLV-based AALs by a factor of greater than 1,000. Cancer potency data from EPA's Integrated Risk Information System suggest significant risks remain at TLV-based AALs. Cancer risks at the median TLV-based AAL exceed 1,000 cases per million exposed persons for cadmium (1,040), nickel and its compounds (1,420), propylene oxide (1,550), coke oven emissions (1,860), benzene (2,500), arsenic and its compounds (7,300), N-nitrosodimethylamine (21,000), asbestos (21,500), and ethylene dibromide (55,000). We also summarize published studies that report non-genotoxic health effects in workers exposed at levels near the TLV for 11 substances whose AALs were based on TLVs. Contrary to the assumption frequently made by state air toxics program, TLVs cannot be taken to represent no observed effect levels (NOELs) for regulatory purposes.

Acrylonitrile↗
PubMed2004

Determination of acute exposure guideline levels in a dispersion model.

The U.S. Environmental Protection Agency (EPA) is in the process of establishing acute exposure guideline levels (AEGLs) for a number of toxic chemicals. These guidelines represent predictable human consequences from measured exposures of selected toxic chemicals over time. They are intended for emergency planning and regulatory purposes. This paper presents a method that can be used by atmospheric dispersion models to compute AEGL values and graphically display the regions exposed to each guideline level on area maps. EPA currently defines three levels of AEGLs corresponding to increasingly severe symptoms, ranging from notable discomfort (AEGL-1) to serious adverse health effects (AEGL-2) to life-threatening effects or death (AEGL-3). For each chemical's three AEGL levels, guideline concentrations are defined for five exposure durations: 10 min, 30 min, 1 hr, 4 hr, and 8 hr. Dispersion models can compute a chemical dosage (time-integrated concentration) and a peak concentration throughout the area exposed to the plume. The AEGL then can be computed by finding the effective duration of the plume at each location, computing the AEGL-equivalent dosages for these durations, and comparing the dosage at each point with the AEGL-equivalent dosages. AEGL contours then can be plotted and readily interpreted in terms of expected toxicity levels for each level of health impact.

Air Pollutants↗
PubMed1999

A survey of EPA/OPP and open literature on selected pesticide chemicals. II. Mutagenicity and carcinogenicity of selected chloroacetanilides and related compounds.

With this effort, we continue our examination of data on selected pesticide chemicals and their related analogues that have been presented to the U.S. Environmental Protection Agency's (USEPA's) Office of Pesticide Programs (OPP). This report focuses on a group of selected chloroacetanilides and a few related compounds. As part of the registration process for pesticidal chemicals, interested parties (registrants) must submit toxicity information to support the registration including both mutagenicity and carcinogenicity data. Although this information is available to the public via Freedom of Information (FOI) requests to the OPP, publication in the scientific literature allows greater dissemination and examination of the data. For this Special Issue, graphic profiles have been prepared of the mutagenicity and carcinogenicity data available in the submissions to OPP. Also, a discussion is presented about how toxicity data are used to help establish tolerances (limits of pesticide residues in foods). The mutagenicity results submitted by registrants are supplemented by data on these chemicals from the open literature to provide a full perspective of their genetic toxicology. The group of chloroacetanilides reviewed here display a consistent pattern of mutagenic activity, probably mediated via metabolites. This mutagenic activity is a mechanistically plausible factor in the development of tumors seen in experimental animals exposed to this class of chemicals.

Acetamides↗
PubMed2000

Mutagenicity of trichloroethylene and its metabolites: implications for the risk assessment of trichloroethylene.

This article addresses the evidence that trichloroethylene (TCE) or its metabolites might mediate tumor formation via a mutagenic mode of action. We review and draw conclusions from the published mutagenicity and genotoxicity information for TCE and its metabolites, chloral hydrate (CH), dichloroacetic acid (DCA), trichloroacetic acid (TCA), trichloroethanol, S-(1, 2-dichlorovinyl)-l-cysteine (DCVC), and S-(1, 2-dichlorovinyl) glutathione (DCVG). The new U.S. Environmental Protection Agency proposed Cancer Risk Assessment Guidelines provide for an assessment of the key events involved in the development of specific tumors. Consistent with this thinking, we provide a new and general strategy for interpreting genotoxicity data that goes beyond a simple determination that the chemical is or is not genotoxic. For TCE, we conclude that the weight of the evidence argues that chemically induced mutation is unlikely to be a key event in the induction of human tumors that might be caused by TCE itself (as the parent compound) and its metabolites, CH, DCA, and TCA. This conclusion derives primarily from the fact that these chemicals require very high doses to be genotoxic. There is not enough information to draw any conclusions for trichloroethanol and the two trichloroethylene conjugates, DCVC and DCVG. There is some evidence that DCVC is a more potent mutagen than CH, DCA, or TCA. Unfortunately, definitive conclusions as to whether TCE will induce tumors in humans via a mutagenic mode of action cannot be drawn from the available information. More research, including the development and use of new techniques, is required before it is possible to make a definitive assessment as to whether chemically induced mutation is a key event in any human tumors resulting from exposure to TCE.

Animals↗
PubMed2002

Combined application of simulated reuse and quantitative carrier tests to assess high-level disinfection: experiments with an accelerated hydrogen peroxide-based formulation.

BACKGROUND: Heat-sensitive medical devices require chemical disinfection between patients, and certain formulations for this purpose can be reused for several days. Because dilution, evaporation, and breakdown or neutralization of active ingredients can occur during reuse, it is vital to ensure that the solution retains its broad-spectrum germicidal activity even at the end of the recommended reuse period. OBJECTIVE: The purpose of this study was to combine the US Environmental Protection Agency's and the Food and Drug Administration's recommended simulated reuse method with recently developed quantitative carrier tests (QCT) to assess the broad-spectrum germicidal activity of a 7% solution of accelerated hydrogen peroxide (pH 2.9) stressed for 14 days. MATERIALS AND METHODS: On alternate days baths with 3 lots of the test formulation were stressed by the addition of bacteria (Salmonella choleraesuis, Staphylococcus aureus, and Pseudomonas aeruginosa ) on glass beads and spores (Bacillus subtilis and Clostridium sporogenes ) on metallic penicylinders. In addition, one set of respiratory therapy equipment was subjected to 3 daily cycles of disinfection in each bath. The pH and H(2)O(2) levels in the test samples were measured, and they were also subjected to QCTs for their sporicidal, bactericidal, virucidal, fungicidal, and mycobactericidal activities. RESULTS: After 14 days of reuse, the pH of the test solutions remained essentially unchanged. Although the level of H(2)O(2) dropped from a high of 7.66% to as low as 6.40%, all lots showed the required level of broad-spectrum germicidal activity after 14 days of stress. CONCLUSIONS: The stress test and QCT were successfully combined in demonstrating the broad-spectrum germicidal activity of a high-level disinfectant subjected to 14 days of simulated reuse.

Chemistry, Pharmaceutical↗
PubMed2001

Risk assessment under FQPA: case study with chlorpyrifos.

Key science policies have had significant impact on the evolving implementation of the Food Quality and Protection Act (FQPA) (PL 104-170, 1996) by the US Environmental Protection Agency (EPA). The impact offour of these policies will be examined using the risk assessment for chlorpyrifos as a case study. These policies are selection of a regulatory endpoint, use of animal data without consideration of human data for setting the reference dose, a 10 FQPA safety factor and use of the 99.9 percentile of modeled consumer exposure in the acute dietary assessment. Each of these policy decisions had individual impact that was then compounded as cumulative impact on the revised risk assessment for chlorpyrifos conducted by the US EPA in 2000 [Federal Register Notice 65(159) (2000) 49982]. But embedded within each science policy, there are assumptions which may be too conservative and which together have resulted in a very large multiplicative reduction in the allowable exposure limits for chlorpyrifos in the US. These new exposure limits are quite different from other regulatory standards around the world. There is third party opposition to many of these policies and many believe the understanding of the relationship between exposure and what is known about human and animal responses to chlorpyrifos has been clouded. These changes in policy insert a new level of conservatism into the scientific statement of risk and create confusion that threatens to weaken the credibility of the regulatory process.

Animals↗
PubMed1996

Technical basis for EPA's proposed regulation on the cleanup of sites contaminated with radioactivity.

The U.S. Environmental Protection Agency is proposing a regulation for the protection of the public from radioactive contamination at sites that are to be cleaned up and released for public use. The rule will apply to sites under the control of Federal agencies, and will impose limits on radiation doses to individuals living or working on a site following cleanup; it will thereby provide site owners and managers with uniform, consistent cleanup criteria for planning and carrying out remediation. This paper presents an overview of EPA's approach to assessing some of the beneficial and adverse effects associated with various possible values for the annual dose limit. In particular, it discusses the method developed to determine how the choice of cleanup criterion affects (1) the time-integrated potential numbers of non-fatal and fatal radiogenic cancers averted among future populations, (2) the occurrence of radiogenic cancers among remediation workers and the public caused by the cleanup process itself, and (3) the volumes of contaminated soil that may require remediation. The analytic methods described here were used to provide input data and assumptions for the Regulatory Impact Analysis (RIA) that supports the proposed regulation; the RIA also considered non-radiological benefits and costs (i.e., public health, economic, and ecological) of the standards.

Radiation Injuries↗
PubMed2000

Consumer and market use of antibacterials at home.

In this increasingly complex, time-constrained world, consumers will continue to look for solutions that promise them peace of mind. A large component of this peace of mind is perceived as personal safety against infectious agents. Manufacturers have a responsibility to provide sound advice and to develop solutions to consumers' questions. Through working with leaders in the infection control field, as well as governmental organizations like the Centers for Disease Control and Prevention, the Food and Drug Administration and the Environmental Protection Agency, manufacturers can develop faster and more effective disinfectant and antimicrobial products. Targeted education programs are needed that clearly and effectively communicate proper infection control techniques and prudent use of antibacterial products to both the consumer and the health professional. Manufacturers should also work closely with the media to educate the public about the potential benefits and risks of their products. Finally manufacturers of household and personal cleaning products should help set guidelines for regulatory monitoring, including correct definition and use of common terms such as antibacterial, antimicrobial, antiviral and sanitization, as well as the extent of protection the consumer can expect from the product.

Centers for Disease Control and Prevention, U.S.↗
PubMed2001

The mammalian safety of Bacillus thuringiensis-based insecticides.

The United States Environmental Protection Agency between the years 1961 and 1995 registered 177 products containing viable Bacillus thuringiensis (Bt). Numerous laboratory studies have demonstrated that Bt and Bt products are noninfectious and are toxic to mammals only at a dose > or =10(8) colony forming units (cfu) per mouse (a human equivalent based on the weight of >10(11) cfu). In contrast, as few as three vegetative cells of Bacillus anthracis can kill mice (a human equivalent of >10(3) cfu). There are only two literature reports of Bt infection in man between the year 1997 and the present, and all infected individuals had experienced either extensive burns or a blast injury, which predisposed them to infection. Two epidemiology studies conducted during large-scale aerial Bt serovar kurstaki spray campaigns reported no increased incidence of illness. Some recent papers have expressed concern about the production of Bacillus cereus enterotoxins by Bt isolates. Laboratory studies found no evidence of illness in rats and sheep fed Bt products, nor have epidemiology studies found increased incidence of diarrhea during Bt aerial spray campaigns. Increases in human antibody levels following exposure to Bt products have been reported but there was no increased incidence in asthma or other illness. Based on laboratory studies and field experience, Bt insecticides have an excellent safety record.

Animals↗