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PubMed1985

The control of organics in drinking water in Canada and the United States (standards, legislation and practice).

Both the United States and Canada have a federal form of government, but approaches used in the two countries to ensure the safety of drinking water supplies differ. The Environmental Protection Agency currently enforces regulations for 10 organic chemicals (including 6 pesticides) under the Safe Drinking Water Act and provides advice on others through its health advisory program. Canada, however, does not have similar legislation, but rather provides health-related guidelines for 21 organic chemicals (including 16 pesticides) which are used by the provincial agencies responsible for drinking water supplies. Both countries are in the process of revising their standards and will include a variety of additional synthetic organic chemicals. Where possible, standards are set using a calculated acceptable daily intake usually derived from animal feeding experiments. Procedures for setting standards for carcinogens involve a blend of risk estimation coupled with consideration of the feasibility of reducing the risk in light of socio-economic factors. Most drinking water treatment plans in North America utilize 'conventional' treatment. Some now employ modifications in order to minimize trihalomethane formation. A few use aeration or granular activated carbon to remove synthetic organic chemicals.

Canada↗
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↗
PubMed1995

Safety/risk assessment of chemicals compared for different expert groups.

Two sets of 65 risk/safety assessments are compared. These assessments, mostly for pesticide chemicals, were developed by the World Health Organization (WHO) and the U.S. Environmental Protection Agency (EPA) at different times, often with different toxicity data, and with slightly different methods. Despite these differences, 38 sets of assessments give values that are within a 3-fold range of each other, 18 of these 38 are essentially identical (when rounded to one digit of precision), although not always for the same reasons. An additional 20 sets give values that lie within a 30-fold range; 6 sets lie within a 300-fold range; and the bromomethane ADI and RfD are 700-fold apart. In addition, on average the EPA values are lower than the WHO numbers. These comparisons are discussed in relationship to a developing world-wide consensus that the methods for evaluating the safety/risks from various chemicals should be more consistent and the resulting assessments should be more comparable. Moreover, we argue that an established assessment and associated information from one expert group should be routinely discussed in the ongoing evaluation of a chemical by another expert group. A procedure for effecting more consistency among such expert groups is proposed.

Environmental Health↗
PubMed1994

Ethylene oxide sterilization: how hospitals can adapt to the changes.

Ethylene oxide (EtO) gas sterilizers have been used by hospitals for over 40 years to sterilize surgical equipment and supplies that are heat sensitive or that cannot tolerate excessive moisture. However, in recent decades, EtO has been recognized as a potential mutagenic, reproductive, neurologic, and fire and explosion hazard to workers, and one agency has reportedly voted to classify EtO as carcinogenic to humans. Strict regulations concerning EtO exposure have been imposed by the Occupational Safety and Health Administration (OSHA), and the use of EtO, along with other toxic pollutants, is also being monitored by the Environmental Protection Agency (EPA) under the Clean Air Act. In addition, the use of chlorofluorocarbons (CFCs) as EtO diluents has focused attention on the EtO-CFC mixtures used in many sterilizers because CFCs have been linked to destruction of the ozone layer. Concerns about restrictive regulations related to these issues have prompted many hospitals to examine their use of EtO sterilization and propagated the misinformation that EtO sterilization is being phased out. In this article, we address some commonly asked questions regarding the use and regulation of EtO mixtures, as well as alternative sterilization agents and methods; provide two case studies illustrating how hospitals can evaluate various sterilization options; and summarize our conclusions and recommendations for hospitals facing decisions about sterilization techniques. For related topics, also see our Evaluation Update on endoscope reprocessors and our Hazard Report on improperly connected EtO-CFC cylinders to EtO sterilizers in this issue.

Air Pollution↗
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↗
PubMed1998

The EPA health risk assessment of methylcyclopentadienyl manganese tricarbonyl (MMT).

This paper describes the U.S. Environmental Protection Agency's assessment of potential health risks associated with the possible widespread use of a manganese (Mn)-based fuel additive, methylcyclopentadienyl manganese tricarbonyl (MMT). This assessment was significant in several respects and may be instructive in identifying certain methodological issues of general relevance to risk assessment. A major feature of the inhalation health risk assessment was the derivation of Mn inhalation reference concentration (RfC) estimates using various statistical approaches, including benchmark dose and Bayesian analyses. The exposure assessment component used data from the Particle Total Exposure Assessment Methodology (PTEAM) study and other sources to estimate personal exposure levels of particulate Mn attributable to the permitted use of MMT in leaded gasoline in Riverside, CA, at the time of the PTEAM study; on this basis it was then possible to predict a distribution of possible future exposure levels associated with the use of MMT in all unleaded gasoline. Qualitative as well as quantitative aspects of the risk characterization are summarized, along with inherent uncertainties due to data limitations.

Administration, Inhalation↗
PubMed2004

Personal exposure meets risk assessment: a comparison of measured and modeled exposures and risks in an urban community.

Human exposure research has consistently shown that, for most volatile organic compounds (VOCs), personal exposures are vastly different from outdoor air concentrations. Therefore, risk estimates based on ambient measurements may over- or underestimate risk, leading to ineffective or inefficient management strategies. In the present study we examine the extent of exposure misclassification and its impact on risk for exposure estimated by the U.S. Environmental Protection Agency (U.S. EPA) Assessment System for Population Exposure Nationwide (ASPEN) model relative to monitoring results from a community-based exposure assessment conducted in Baltimore, Maryland (USA). This study is the first direct comparison of the ASPEN model (as used by the U.S. EPA for the Cumulative Exposure Project and subsequently the National-Scale Air Toxics Assessment) and human exposure data to estimate health risks. A random sampling strategy was used to recruit 33 nonsmoking adult community residents. Passive air sampling badges were used to assess 3-day time-weighted-average personal exposure as well as outdoor and indoor residential concentrations of VOCs for each study participant. In general, personal exposures were greater than indoor VOC concentrations, which were greater than outdoor VOC concentrations. Public health risks due to actual personal exposures were estimated. In comparing measured personal exposures and indoor and outdoor VOC concentrations with ASPEN model estimates for ambient concentrations, our data suggest that ASPEN was reasonably accurate as a surrogate for personal exposures (measured exposures of community residents) for VOCs emitted primarily from mobile sources or VOCs that occur as global "background" source pollutant with no indoor source contributions. Otherwise, the ASPEN model estimates were generally lower than measured personal exposures and the estimated health risks. ASPEN's lower exposures resulted in proportional underestimation of cumulative cancer risk when pollutant exposures were combined to estimate cumulative risk. Median cumulative lifetime cancer risk based on personal exposures was 3-fold greater than estimates based on ASPEN-modeled concentrations. These findings demonstrate the significance of indoor exposure sources and the importance of indoor and/or personal monitoring for accurate assessment of risk. Environmental health policies may not be sufficient in reducing exposures and risks if they are based solely on modeled ambient VOC concentrations. Results from our study underscore the need for a coordinated multimedia approach to exposure assessment for setting public health policy.

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↗
PubMed2005

Criteria and air-toxic emissions from in-use automobiles in the National Low-Emission Vehicle program.

The U.S. Environmental Protection Agency (EPA) implemented a program to identify tailpipe emissions of criteria and air-toxic contaminants from in-use, light-duty low-emission vehicles (LEVs). EPA recruited 25 LEVs in 2002 and measured emissions on a chassis dynamometer using the cold-start urban dynamometer driving schedule of the Federal Test Procedure. The emissions measured included regulated pollutants, particulate matter, speciated hydrocarbon compounds, and carbonyl compounds. The results provided a comparison of emissions from real-world LEVs with emission standards for criteria and air-toxic compounds. Emission measurements indicated that a portion of the in-use fleet tested exceeded standards for the criteria gases. Real-time regulated and speciated hydrocarbon measurements demonstrated that the majority of emissions occurred during the initial phases of the cold-start portion of the urban dynamometer driving schedule. Overall, the study provided updated emission factor data for real-world, in-use operation of LEVs for improved emissions modeling and mobile source inventory development.

Air Pollutants↗
PubMed1997

Risk characterization: A bridge to informed decision making.

Regulatory decisions should be made in the most expert and informed way since they are precipitated by real and perceived threats to human health, under the glare of public scrutiny. In 1994, the National Research Council (NRC) reported that the U.S. Environmental Protection Agency's (USEPA's) overall approach to assessing risks is fundamentally sound, but the Agency must more clearly establish the scientific and policy basis for risk estimates and better communicate the associated uncertainties. On March 21, 1995, USEPA issued a risk characterization policy and guidance. In this policy, an effective risk characterization must fully and clearly characterize risks and disclose the scientific analysis, uncertainties, assumptions, and science policy that underlie decisions throughout the risk assessment process. A number of regulatory reform bills which required risk characterization as part of all Federal risk assessments were introduced by the 104th Congress. The purpose of this workshop was to familiarize Society of Toxicology members with: (1) key elements to be considered in risk characterization and (2) new advances in risk characterization addressed by Federal and State agencies, industry, academia, NRC, and Presidential/Congressional Commission on Risk Assessment and Risk Management. Furthermore, the main objective was to engage the audience in discussing the proper role of science in risk assessment-risk management interface to make informed decisions in the face of scientific uncertainty.

Decision Making↗
PubMed2001

Simplified analysis of contaminant rejection during ground- and surface water nanofiltration under the information collection rule.

A simple, closed-form analytical expression based on the homogenous solution diffusion model is derived for contaminant removal during nanofiltration (NF) of ground and surface water. Solute permeation and back-diffusion coefficients were used as fitting parameters to model rejection characteristics of four thin-film composite NF membranes under conditions typical of drinking water NF. Nonlinear fits of the model to experimental data suggests that the United States Environmental Protection Agency's (USEPA)'s Information Collection Rule protocol for bench-scale studies could be improved to obtain greater precision of the mass transfer coefficients. The model was found to fit rejection data for several water treatment contaminants including total organic carbon, precursors to total organic halide, four trihalomethanes and nine haloacetic acids containing chlorine and bromine, calcium and total hardness, alkalinity and conductivity. The simplified approach to mass transfer calculations from multisolute systems suggests that feed water recovery has a stronger influence on contaminant rejection than permeate flux. Evidence for coupled transport of divalent inorganic ions is also presented. Even though the model developed does not account for ion coupling and cannot be applied in a purely predictive mode, it can assist in the better design and interpretation of data obtained from site-specific pilot-scale water treatment NF studies conducted in support of plant design.

Acetates↗
PubMed1996

Research needs for the risk assessment of health and environmental effects of endocrine disruptors: a report of the U.S. EPA-sponsored workshop.

The hypothesis has been put forward that humans and wildlife species adverse suffered adverse health effects after exposure to endocrine-disrupting chemicals. Reported adverse effects include declines in populations, increases in cancers, and reduced reproductive function. The U.S. Environmental Protection Agency sponsored a workshop in April 1995 to bring together interested parties in an effort to identify research gaps related to this hypothesis and to establish priorities for future research activities. Approximately 90 invited participants were organized into work groups developed around the principal reported health effects-carcinogenesis, reproductive toxicity, neurotoxicity, and immunotoxicity-as well as along the risk assessment paradigm-hazard identification, dose-response assessment, exposure assessment, and risk characterization. Attention focused on both ecological and human health effects. In general, group felt that the hypothesis warranted a concerted research effort to evaluate its validity and that research should focus primarily on effects on development of reproductive capability, on improved exposure assessment, and on the effects of mixtures. This report summarizes the discussions of the work groups and details the recommendations for additional research.

Animals↗
PubMedDate not supplied

[Temporal and spatial variations of coliforms and Escherichia coli in fluvial recreational waters (Salado River, Santa Fe, Argentina). Relationship with the quality standards].

There are no standards accepted by all the countries to fix top concentrations of microbiological indicators in recreational waters. Even now there is still a considerable discussion either in USA as in Europe. The universal application of a bacteriological quality criterion is hard due to several environmental factors that affect the relation between the indicator, the exposition and the health risks. Our purpose was to present a case study as an example of the influence of the climatic conditions in the application of the most known standards (Environmental Protection Agency of USA, Council of European Communities, World Organization of Health, and others from Canada, South Africa and Hong Kong). The pluvial rainfall increased the number of E. coli, thermotolerant coliforms (C Te), and total coliforms (CT) 6-10 fold, in comparison to the number registered during the steady-state conditions of the system. However, not all the standards included that factor. In Summer, hourly, daily and weekly variations were proved, therefore the standards that suggest fortnightly sampling frequencies would not be convenient in that system. Although the main source of variation was time, spatial variability was also detected. The percentage of E. coli among the C Te was very variable, but the average resulted low (26%) compared to the levels in temperate regions of other countries (> 90%). According to the directives proposed by the Commission of European Communities, the parameter has been changed (C Te for E. coli), but the standard has remained (2000/100 ml). Thus, the directive would be more permissive.

Argentina↗
PubMedDate not supplied

Respiratory hospital admissions associated with PM10 pollution in Utah, Salt Lake, and Cache Valleys.

This study assessed the association between respiratory hospital admissions and PM10 pollution in Utah, Salt Lake, and Cache valleys during April 1985 through March 1989. Utah and Salt Lake valleys had high levels of PM10 pollution that violated both the annual and 24-h standards issued by the Environmental Protection Agency (EPA). Much lower PM10 levels occurred in the Cache Valley. Utah Valley experienced the intermittent operation of its primary source of PM10 pollution: an integrated steel mill. Bronchitis and asthma admissions for preschool-age children were approximately twice as frequent in Utah Valley when the steel mill was operating versus when it was not. Similar differences were not observed in Salt Lake or Cache valleys. Even though Cache Valley had higher smoking rates and lower temperatures in winter than did Utah Valley, per capita bronchitis and asthma admissions for all ages were approximately twice as high in Utah Valley. During the period when the steel mill was closed, differences in per capita admissions between Utah and Cache valleys narrowed considerably. Regression analysis also demonstrated a statistical association between respiratory hospital admissions and PM10 pollution. The results suggest that PM10 pollution plays a role in the incidence and severity of respiratory disease.

Adolescent↗
PubMed2006

Validation of the digital opacity compliance system under regulatory enforcement conditions.

U.S. Environmental Protection Agency (EPA) Emission Measurement Center in conjunction with EPA Regions VI and VIII, the state of Utah, and the U.S. Department of Defense have conducted a series of long-term pilot and field tests to determine the accuracy and reliability of a visible opacity monitoring system consisting of a conventional digital camera and a separate computer software application for plume opacity determination. This technology, known as the Digital Opacity Compliance System (DOCS), has been successfully demonstrated at EPA-sponsored Method-9 "smoke schools", as well as at a number of government and commercially operated industrial facilities. Results from the current DOCS regulatory pilot study demonstrated that, under regulatory enforcement conditions, the average difference in opacity measurement between the DOCS technology and EPA Reference Method 9 (Method 9) was 1.12%. This opacity difference, which was computed from the evaluation of 241 regulated air sources, was found to be statistically significant at the 99% confidence level. In evaluating only those sources for which a nonzero visible opacity level was recorded, the

Air Pollutants↗
PubMed1993

Health risk assessment.

In the United States the hazards posed by chemicals are often enormously exaggerated. In "calculating" risks of human cancer and establishing regulations, the United States Environmental Protection Agency makes a series of "conservative" assumptions that have no sound scientific basis. In consequence, trillions of dollars could be wasted. Exaggerations of risks are inherent in the procedures by which rodents are employed as stand-ins for humans. Dependence on results of maximum tolerated doses in the most sensitive strain or species of rodent is questionable. Important examples involve B6C3F1 mice, which in contrast to humans in developed countries, have a high control incidence of liver cancer. Those mice often respond with liver tumors when exposed to large doses of a substance. Other rodents are less often affected. Questionable assessments involving liver cancer in B6C3F1 mice include the risks posed by trichloroethylene, perchloroethylene, methylene chloride, butadiene, and phenobarbital. Spurious assessments for humans have also been noted when the male rat was the most sensitive animal. A unique mechanism in them gives rise to kidney tumors while female rats and male and female mice are not affected.

Animals↗