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PubMed1995

A trichloroethylene risk assessment using a Monte Carlo analysis of parameter uncertainty in conjunction with physiologically-based pharmacokinetic modeling.

A Monte Carlo simulation is incorporated into a risk assessment for trichloroethylene (TCE) using physiologically-based pharmacokinetic (PBPK) modeling coupled with the linearized multistage model to derive human carcinogenic risk extrapolations. The Monte Carlo technique incorporates physiological parameter variability to produce a statistically derived range of risk estimates which quantifies specific uncertainties associated with PBPK risk assessment approaches. Both inhalation and ingestion exposure routes are addressed. Simulated exposure scenarios were consistent with those used by the Environmental Protection Agency (EPA) in their TCE risk assessment. Mean values of physiological parameters were gathered from the literature for both mice (carcinogenic bioassay subjects) and for humans. Realistic physiological value distributions were assumed using existing data on variability. Mouse cancer bioassay data were correlated to total TCE metabolized and area-under-the-curve (blood concentration) trichloroacetic acid (TCA) as determined by a mouse PBPK model. These internal dose metrics were used in a linearized multistage model analysis to determine dose metric values corresponding to 10(-6) lifetime excess cancer risk. Using a human PBPK model, these metabolized doses were then extrapolated to equivalent human exposures (inhalation and ingestion). The Monte Carlo iterations with varying mouse and human physiological parameters produced a range of human exposure concentrations producing a 10(-6) risk.

Administration, Inhalation↗
PubMed2006

Assessing sites contaminated with unexploded ordnance: statistical modeling of ordnance spatial distribution.

More than 40,000 km2 of former military land in the United States are contaminated with unexploded ordnance (UXO). Cleanup costs are estimated to total as much as 140 billion dollars. The amount of contaminated acreage and total costs are likely to increase as the U.S. Department of Defense (DOD) follows through on recently announced plans to close an additional 22 domestic military bases. The U.S. Environmental Protection Agency(EPA) and DOD disagree on how these sites should be characterized to assess their risks and plan for cleanup. As a result, much potentially valuable land remains idle while remediation decisions are pending. One of the sources of disagreement is how the locations of UXO should be characterized, given that the exact spatial distribution of UXO is unknown in advance of cleanup. In this paper, we propose and test a new model to represent the spatial distribution of UXO. Unlike existing DOD models, the new model accounts for the tendency of UXO to cluster, presumably around targets at which soldiers aimed during training. We fit the cluster model to geographic data on UXO locations at two former military installations and show that it describes key characteristics of the data more accuratelythan the existing DOD model. We discuss how the choice of a UXO spatial distribution model could affect important decisions about cleaning up and reusing UXO-affected property.

Environmental Monitoring↗
PubMed1994

Asbestos in New York City public school buildings--public policy: is there a scientific basis?

The most recent of New York City's asbestos emergencies occurred in the late summer of 1993. It prevented schools from opening that fall, precipitated much media excitement, and caused a flurry of widespread abatement activities. This resulted in large measure from the U.S. Environmental Protection Agency's subjective school building inspection policy concerning identification of asbestos hazards in buildings and the subsequent Asbestos Hazard Emergency Response Act mandate for inspection. Data on concentrations of asbestos in the air, important for the calculation of risk to building occupants, were not required and therefore not obtained, as part of the abatement strategy or priority setting. Based on fiber-in-air measurements obtained elsewhere, the calculated risk to NYC school children, using the most pessimistic models, was less than six excess cancer deaths per million lifetimes equivalent to smoking less than a dozen cigarettes in a lifetime. The NYC administration responded to pressure from parent groups concerned with perceived asbestos risks to their children by closing the schools. The hysteria occurred because much of EPA's policy lacked a scientific basis for risk evaluation and assessment.

Air Pollution, Indoor↗
PubMed1984

Disposal of antineoplastic wastes at the National Institutes of Health.

The process of developing disposal guidelines for antineoplastic wastes at the National Institutes of Health (NIH) is described. Because of the large volume of hazardous wastes generated, NIH must comply with Environmental Protection Agency (EPA) guidelines for disposal. Seven antineoplastic agents are defined by EPA as hazardous wastes. Because of the similar toxicities and pharmacologic drugs, NIH officials elected to dispose of all such agents as hazardous wastes. Available options are presented. The NIH procedure divides antineoplastic wastes into trace- and bulk-contaminated categories. Trace-contaminated wastes contain minimal or trace amounts of drugs and are disposed of by one-site incineration. Bulk-contaminated materials (defined as intravenous solutions or containers whose contents weigh more than 3% of the capacity of the container) are disposed of by land internment and incineration at EPA-approved sites. Syringes and i.v. bottles containing antineoplastic drugs are labeled with bright red-orange labels instructing personnel to return the materials to the pharmacy for disposal. General decision-making procedures for other institutions are recommended.

Antineoplastic Agents↗
PubMed1991

Comparing alternative approaches to establishing regulatory levels for reproductive toxicants: DBCP as a case study.

This paper compares four alternative approaches for deriving regulatory levels for reproductive toxicants by applying them to the available data on the human spermatotoxicant 1,2-dibromo-3-chloropropane (DBCP). The alternatives examined include the Proposition 65 approach (application of a mandatory 1000-fold uncertainty factor to a no-observed-adverse-effect level [NOAEL]), the Environmental Protection Agency (EPA) approach (application of flexible uncertainty factors to a NOAEL), the Benchmark Dose approach (application of flexible uncertainty factors to a dose associated with a known level of change in a reproductive parameter), and the Quantitative Risk Estimation approach (using low-dose linear extrapolation and a model of the relationship between sperm count and infertility). Applied to DBCP, these approaches do not produce substantially different estimates of allowable exposure levels. However, the approaches do have different data requirements and provide different amounts of information on reproductive hazards to risk managers and the public. Neither the Proposition 65 nor the EPA approach provides information about the extent of health risk remaining at a regulatory level. In contrast, the Benchmark Dose approach can provide estimates of the magnitude of sperm count reduction at a regulatory level, and the Quantitative Risk Estimation approach can provide estimates of exposure-induced infertility.

Animals↗
PubMed1995

Applying the Good Laboratory Practice regulations to studies involving genetically modified plants.

How can the Environmental Protection Agency's Good Laboratory Practice (GLP) regulations, originally written primarily for mammalian toxicology studies, be applied to regulatory studies conducted for genetically modified plants? Do they fit? Can they be applied and still make sense? How is a Quality Assurance Unit (QAU) to interpret the requirements in this new area of biotechnology? The answers to these questions are discussed in this brief presentation of how one team within the Monsanto QAU, along with the researchers, developed am effective and comprehensive compliance program by applying the "traditional approach" to the GLP regulations to a new and important scientific field in regulatory compliance. Topics discussed will address the differences in the approach between traditional toxicity testing and the newer technology and how the differences were resolved, new and innovative definitions of particular phases and other aspects of regulatory studies, and how the draft regulations for pesticidal plants will help this area of technology in the future.

Animals↗
PubMed2000

New methods for detection of potential endocrine disruptors.

It has been hypothesized that recent adverse trends in humans are linked to an increased exposure to potential endocrine disrupting agents. These include widely used compounds that mimic the action of sex hormones, including bisphenol A, phthalates and parabens. Since the chemical structure is not sufficient to determine whether a chemical will act as an oestrogen, there is a need for assays that can determine whether a compound interferes with the endocrine systems. The Environmental Protection Agency has recently suggested a testing scheme, composed of an initial screening followed by a more comprehensive investigation of chemicals that are positive in the screening. The screening will use several short-term assays to screen many thousands of compounds for potential endocrine disrupting properties. However, none of these tests determines compound-induced effects on the expression of endogenous genes, which is the cause of the adverse effects. We propose to use a precise quantification of the expression levels of endogenous oestrogen-regulated genes to test whether a chemical has oestrogenic properties, and describe how an endogenous gene expression assay can be established and conducted. Furthermore, different applications of such an assay are discussed: in cell cultures; in experimental animals; or, optimally, directly in blood samples from exposed humans.

Animals↗
PubMed2003

A cost-effective method for detoxification of sludge containing lead.

The industrial wastewater treatment plant discussed in this paper generates sludge containing heavy metals, including lead. Occasionally, the concentration of lead in the Toxic Characteristics Leaching Procedure (TCLP) extract from the sludge exceeded the U.S. Environmental Protection Agency (EPA) regulatory limit of 5 mg/l and resulted in the solid waste exhibiting the characteristic of toxicity. The technical and economic feasibility of a process for conditioning the lead-containing sludge was investigated. The results revealed that the lead-laden sludge could be made non-hazardous by chemical conditioning. The lead reduction efficiency of triple super phosphate (TSP) is higher than that of either calcium carbonate or magnesium hydroxide. The laboratory and pilot-scale tests indicated that the conditioning system consistently reduced the lead in the TCLP extract below the regulatory limit of 5 mg/l. The economic feasibility evaluation demonstrated that more than 450,000 US dollars could be saved annually by conditioning the sludge with TSP and disposing it as a non-hazardous material in a landfill. The results obtained from the laboratory as well as from the pilot-scale operation are described and discussed in this paper.

Calcium Carbonate↗
PubMed2000

Genetic technologies. Bioengineered food--safety and labeling.

The safety and labeling of genetically engineered foods are two areas that have elicited considerable public concern and debate. This Policy Forum provides a legal analysis of these issues in the context of two bills that have been recently proposed in The U.S. Congress, the Genetically Engineered Food Safety Act and the Genetically Engineered Food Right to Know Act. Most transgenic components of foods currently on the market are plant-incorporated protectants or their inert ingredients. Therefore, they have been evaluated for safety by the Environmental Protection Agency (as well as the Food and Drug Administration), and their disclosure in labeling should not be required. If plant-incorporated protectants are considered safer than chemical pesticides, and chemical pesticides do not have to be disclosed in labels, then bioengineered foods should not be subject to stricter regulation, nor should they be required to be labeled. The two bills are inconsistent, in many respects, with well-established principles of food regulation.

Animals↗
PubMed1999

On intergenerational equity and its clash with intragenerational equity and on the need for policies to guide the regulation of disposal of wastes and other activities posing very long-term risks.

This article begins with some history of the derivation of 40 CFR Part 191, the U.S. Environmental Protection Agency (EPA) standard that governs the geologic disposal of spent nuclear fuel and high-level and transuranic radioactive wastes. This is followed by criticisms of the standard that were made by a Sub-Committee of the EPA Science Advisory Board, by the staff of the U.S. Nuclear Regulatory Commission, and by a panel of the National Academies of Science and Engineering. The large disparity in the EPA approaches to regulation of disposal of radioactive wastes and disposal of hazardous, long-lived, nonradioactive chemical waste is illustrated. An examination of the intertwined matters of intergenerational equity and the discounting of future health effects follows, together with a discussion of the conflict between intergenerational equity and intragenerational equity. Finally, issues related to assumptions in the regulations concerning the future state of society and the biosphere are treated, as is the absence of any national philosophy or guiding policy for how to deal with societal activities that pose very long-term risks.

History, 20th Century↗
PubMed2001

Probabilistic risk assessment of cotton pyrethroids: V. Combining landscape-level exposures and ecotoxicological effects data to characterize risks.

Since their introduction, synthetic pyrethroid insecticides have generated regulatory concerns regarding their toxicity to fish and aquatic invertebrates. In this paper we assess the potential for risks to aquatic ecosystems in cotton-growing areas, focusing on cypermethrin as a suitable representative of the pyrethroid class and static water bodies (ponds and lakes) as worst-case water bodies because of low levels of dilution. Reviews of cypermethrin effects under laboratory and field conditions have characterized the potential aquatic effects of the chemical. Also, a landscape-level exposure characterization has been conducted in a worst-case cotton-growing county, Yazoo County, Mississippi, USA, to provide a more realistic exposure characterization than is possible using standard model scenarios. Risks were characterized using the standard tier I and II approaches of the U.S. Environmental Protection Agency. In addition, a probabilistic risk assessment was conducted by comparing landscape-level exposure calculations for ponds and lakes in Yazoo County (modified tier II analysis) with distributions of laboratory effect concentrations and with data from field studies. Risk characterization using tier I and tier II models demonstrated a level of concern for certain aquatic organisms. However, modified tier II analysis showed that exposure concentrations are unlikely to exceed concentrations that might cause ecologically significant effects. Indeed, in the vast majority of cases, concentrations in the modified tier II analysis were several orders of magnitude lower than those at which effects would be predicted on the basis of laboratory and field data. The conclusion of minimal potential for adverse ecological effects was also supported by field studies, which showed that impacts on aquatic systems were negligible, even at concentrations many times higher than the modified tier II exposure concentrations.

Animals↗
PubMed2004

Quality and quantity of suspended particles in rivers: continent-scale patterns in the United States.

Suspended solids or sediments can be pollutants in rivers, but they are also an important component of lotic food webs. Suspended sediment data for rivers were obtained from a United States-wide water quality database for 622 stations. Data for particulate nitrogen, suspended carbon, discharge, watershed area, land use, and population were also used. Stations were classified by United States Environmental Protection Agency ecoregions to assess relationships between terrestrial habitats and the quality and quantity of total suspended solids (TSS). Results indicate that nephelometric determinations of mean turbidity can be used to estimate mean suspended sediment values to within an order of magnitude (r(2) = 0.89). Water quality is often considered impaired above 80 mg TSS L(-1), and 35% of the stations examined during this study had mean values exceeding this level. Forested systems had substantially lower TSS and somewhat higher carbon-to-nitrogen ratios of suspended materials. The correlation between TSS and discharge was moderately well described by an exponential relationship, with the power of the exponent indicating potential acute sediment events in rivers. Mean sediment values and power of the exponent varied significantly with ecoregion, but TSS values were also influenced by land use practices and geomorphological characteristics. Results confirm that, based on current water quality standards, excessive suspended solids impair numerous rivers in the United States.

Carbon↗
PubMed2006

Field evaluation of an avian risk assessment model.

We conducted two laboratory subacute dietary toxicity tests and one outdoor subacute dietary toxicity test to determine the effectiveness of the U.S. Environmental Protection Agency's deterministic risk assessment model for evaluating the potential of adverse effects to birds in the field. We tested technical-grade diazinon and its D.Z.N 50W (50% diazinon active ingredient wettable powder) formulation on Canada goose (Branta canadensis) goslings. Brain acetylcholinesterase activity was measured, and the feathers and skin, feet, and gastrointestinal contents were analyzed for diazinon residues. The dose-response curves showed that diazinon was significantly more toxic to goslings in the outdoor test than in the laboratory tests. The deterministic risk assessment method identified the potential for risk to birds in general, but the factors associated with extrapolating from the laboratory to the field, and from the laboratory test species to other species, resulted in the underestimation of risk to the goslings. The present study indicates that laboratory-based risk quotients should be interpreted with caution.

Acetylesterase↗
PubMed1999

Comparative study of spray booth filter system efficiency.

During recent years, greater emphasis has been placed on the control of particulate emissions from painting operations. This has gained more importance as more is learned about the potential release of toxic metals to the atmosphere from painting operations. This has led to queries about the efficiency of various painting arrestor systems to reduce particulate discharges to the atmosphere. Even more important is the capability of the arrestor systems to control PM10 emissions. In 1995, the U.S. Environmental Protection Agency initiated a study to evaluate various dry paint overspray arrestor systems. This study was designed to evaluate not only the total emissions control capability of the arrestor but also the PM10 control capability of the various system designs. Paint overspray arrestor systems using five different filtration concepts or materials were selected. They include systems constructed of fiberglass, paper, Styrofoam, and cardboard materials. These systems used filtration techniques incorporating the following filtration phenomena and designs: cyclone, baffle, bag systems, and mesh systems. The testing used an optical particle counting procedure to determine the concentration of particles of a given size fraction to penetrate a test arrestor system. The results of the testing indicated that there are significant differences in the efficiency of the tested system designs to capture and retain PM10. This paper summarizes the results of the research conducted to determine the capability of the arrestor systems to capture particulate of sizes down to approximately 1 micron in surface diameter.

Air Pollutants, Occupational↗
PubMed1996

Toward a more realistic appraisal of the lung cancer risk from radon: the effects of residential mobility.

OBJECTIVES: A consideration of the effects of residential mobility produces much more realistic estimates of typical individuals' radon exposures and mortality risks than those of the Environmental Protection Agency (EPA). METHODS: A model linking residential mobility, the distribution of radon in US homes, and lung cancer risk is used to simulate lifetime radon exposure, with and without mitigation of high-radon homes, for typical mobile individuals. Radon-related lung cancer mortality risks are then estimated for smokers and never-smokers. RESULTS: Most individuals residing in high-radon homes have equivalent lifelong radon exposures well below those they are currently experiencing. Consequently, actual lung cancer risks are generally well below those implied in the EPA's radon risk charts. For most people who mitigate high-radon homes, risk reduction is modest. CONCLUSIONS: Radon may indeed be responsible for as large a population risk of lung cancer as the EPA estimates. However, caution must be used in interpreting the EPA's risk assessment for individuals; in many cases, mitigation will have little effect on residents' health risks.

Adult↗
PubMed1992

Uncertainty in risk assessment: exceedence frequencies, acceptable risk, and risk-based decision making.

The use of "exceedence frequencies" is proposed as a means of evaluating the acceptability of uncertain environmental risks. A survey was conducted of U.S. Environmental Protection Agency personnel. When respondents were requested to identify preferred "acceptable" exceedence frequencies at four different regulatory risk thresholds (10(-3) to 10(-6), three general response patterns were found: "absolutist" responses in which no level of exceedence was deemed acceptable; "fixed" responses in which respondents felt that the level of exceedence should remain constant at all risk levels; and "outcome sensitive" responses in which preferred exceedence frequencies were inversely related to the risk level. This last group's responses were based on the rationale that the "marginal cost" of risk (in terms of expected mortalities) increases as the risk threshold increases. Although the majority of respondents accepted the concept of an acceptable risk exceedence frequency, the low exceedence frequencies selected as being "acceptable" by survey respondents (generally 5% or less) appear to be overly conservative given the degree of uncertainty inherent in risk assessments. Finally, two regulatory uses of exceedence frequencies are proposed as a tool for streamlined risk ranking.

Attitude of Health Personnel↗
PubMedDate not supplied

Workshop on the qualitative and quantitative comparability of human and animal developmental neurotoxicity: summary and implications.

The Workshop on the Qualitative and Quantitative Comparability of Human and Animal Developmental Neurotoxicity was convened by the U.S. Environmental Protection Agency (EPA) and the National Institute on Drug Abuse to address issues related to when testing should be required, what test methodologies should be required, and how the data should be interpreted and applied to the risk assessment process. The background material for Work Group discussions included presentations made at the Workshop by invited experts summarizing qualitative and quantitative human and experimental animal data on specific chemicals or classes of chemicals and EPA's proposed developmental neurotoxicity testing protocol. This overview: 1) summarizes the qualitative comparisons presented at the Workshop and attempts to make some quantitative comparisons of findings across mammalian species following exposure to developmental neurotoxicants, 2) brings the common themes that were discussed among the Work Groups together into a regulatory perspective, 3) provides a status report on EPA's developmental neurotoxicity protocol, and 4) identifies research needs in the development of test methodologies and improvement of risk assessments for developmental neurotoxicants.

Animals↗
PubMed1993

Acid Rain Program: general provisions and permits, allowance system, continuous emissions monitoring, excess emissions and administrative appeals--EPA. Final rule.

Title IV of the Clean Air Act (the Act), as amended November 15, 1990, requires the Environmental Protection Agency (EPA or Agency) to establish an Acid Rain Program to reduce the adverse effects of acidic deposition. To implement this statutory mandate, the Acid Rain Program requirements will be codified in seven regulations. This action delineates all or portions of five final regulations that were initially proposed December 3, 1991: General Provisions and Permits; the Allowance System; Continuous Emissions Monitoring; Excess Emissions Penalties; and Administrative Appeals. (The administrative appeals procedures were originally proposed as a subpart of the permits rule; EPA has decided to remove it from part 72 and place it in a separate part 78.) In addition to the final rules, this action includes a brief overview of the acid rain problem, summaries of major provisions of the proposed rules, the public's comments on these proposals, and summaries of the major changes that have been made in this final rule. DATES: These rules become effective February 10, 1993. The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of February 10, 1993.

Acid Rain↗