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The small crucifer Arabidopsis is very economical for short-term yet complete assay for chemical mutagens. Thousands of gene loci can be simultaneously monitored for alterations within one culture by screening for segregation among the embryos (M2) developing on the M1 plants. This species is quite sensitive to a wide range of compounds and can activate promutagens to mutagens. There is a very high correlation between mutagenic responses of Arabidopsis and carcinogenicity in animals.
The hybrid diploid clone 4430- of the plant Tradescantia is heterozygous for a flower color locus. Its blue phenotype is the product of the dominant blue allele, and its pink phenotype is controlled by a recessive pink allele unmasked by mutation or deletion of the blue allele. Somatic cell mutants in the filamentous stamen hair are scored to measure mutagenic effect. The plant is used for tests conducted in the field and laboratory alike, and it is uniquely suited for the detection of gaseous mutagens.
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The nature of both indoor air exposures and noncancer end points present significant issues for risk characterization. Noncancer end points are multidimensional, affecting various organs, and are assumed to have thresholds. Symptoms also vary in severity within a population. In addition to the complexity of noncancer risk assessment, indoor air exposures are typified by the presence of complex mixtures, which further complicates the complex nature of noncancer risk characterization. Most noncancer risk assessment efforts have focused on defining acceptable daily intakes or reference doses (RfD) rather than estimating incidence and severity of the wide range of effects within an exposed population. The risk characterization framework has been developed to accommodate the RfD approach but, more importantly, to address the multidimensional nature of noncancer risk characterization. Newly emerging methods and standard EPA risk assessment guidelines for noncancer effects and complex mixtures were used as guides for developing the framework. Information and data needs have been identified from the framework. Peak, average, and cumulative doses from indoor air exposures are highly dependent on variable indoor air concentrations and affected by time-activity patterns. Susceptibility also plays a significant role in noncancer end points and, unlike susceptibility in cancer risk assessment, is quantifiable. This paper highlights the risk characterization framework for noncancer health risks that we developed in cooperation with the U.S. Environmental Protection Agency Environmental Criteria and Assessment Office. Additionally, a preliminary application of the framework to a complex mixture of volatile organic compounds from indoor sources is illustrated.
The U.S. Environmental Protection Agency Environmental Monitoring and Assessment Program (EMAP) uses water clarity as a water quality indicator for integrated assessments of coastal waters. After the publication of the first National Coastal Condition Report (USEPA, 2001c), the national water clarity reference value of 10% of ambient surface light at 1 m depth was reevaluated and modified to reflect expected differences in regional reference light conditions. These regional differences range from naturally turbid estuaries like those found in Mississippi and Louisiana to clear water estuaries expected to support extensive beds of submerged aquatic vegetation in, e.g., Florida and Tampa Bays. For the second National Coastal Condition Report, water clarity was assessed based on regional reference values (USEPA, 2004). Different regional water clarity reference values and data collection methods necessitated the development of a water clarity index based on light attenuation coefficients (k). This index incorporates regional reference conditions and is interchangeable with secchi depth and percent light transmission calculated from light meter measurements. Evaluation of the water clarity index shows that k values based on transmissivity at 1 m can be estimated from secchi depth measurements and successfully used as a surrogate for transmissivity calculated from light meter data. An approach for assessing water clarity in Gulf of Mexico estuaries using light meter data and secchi depth is presented.
Fine particulate matter (PM2.5) mass was determined on a continuous basis at the Salt Lake City Environmental Protection Agency Environmental Monitoring for Public Awareness and Community Tracking monitoring site in Salt Lake City, UT, using three different monitoring techniques. Hourly averaged PM2.5 mass data were collected during two sampling periods (summer 2000 and winter 2002) using a real-time total ambient mass sampler (RAMS), sample equilibration system (SES)-tapered element oscillating microbalance (TEOM), and conventional TEOM monitor. This paper compares the results obtained from the various monitoring systems, which differ in their treatment of semivolatile material (SVM; particle-bound water, semivolatile ammonium nitrate, and semivolatile organic compounds). PM2.5 mass results obtained by the RAMS were consistently higher than those obtained by the SES-TEOM and conventional TEOM monitors because of the RAMS ability to measure semivolatile ammonium nitrate and semivolatile organic material but not particle-bound water. The SES-TEOM monitoring system was able to account for an average of 28% of the SVM, whereas the conventional TEOM monitor loses essentially all of the SVM from the single filter during sampling. Occasional mass readings by the various TEOM monitors that are higher than RAMS results may reflect particle-bound water, which, under some conditions, is measured by the TEOM but not the RAMS.
The problem of elevated levels of radium in the drinking-water supply of DeKalb, Illinois, a Midwestern community about 65 miles west of Chicago with approximately 35,000 residents, has been a contentious issue for over a decade. The central players in the controversy include a group of concerned citizens, city officials, the Illinois Pollution Control Board, the Illinois Environmental Protection Agency, and the U.S. Environmental Protection Agency (U.S. EPA). Achieving a satisfactory resolution to the problem has been a long, drawn-out process that illustrates how ill-timed proposals, changing risk assessments, different perceptions of risk, and the high costs of compliance can influence the direction of risk management decisions. The purpose of this study is to analyze how these factors sustained the debate and prevented an expeditious solution to the problem. The study uses document analysis as its primary research tool. The questions raised by the controversy, along with their implications for environmental policy, are discussed, as are some of the more important lessons learned from the case. Because of many uncertainties, there were no clear winners in the controversy, although, in the context of the most recent U.S. EPA risk assessments, the community is now poised for better protection from the potential dangers of radium in drinking water than it might have been had citizen action been absent.
Bioassessment of nonwadeable streams in the United States is increasing, but methods for these systems are not as well-developed as for wadeable streams. In this study, we compared six macroinvertebrate field sampling methods for nonwadeable streams adapted from those used by three major programs: the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program-Surface Waters, the U.S. Geological Survey's National Water Quality Assessment Program, and the Ohio Environmental Protection Agency, Division of Surface Water Biocriteria Program. We performed all six methods at 60 sites across four rivers and measured water chemistry and physical habitat at each site to assess abiotic conditon. Sites were divided into two groups: those influenced by navigational lock and dam structures (restricted flow, or RF) and those free-flowing or with lowhead dams (run-of-the-river, or ROR). Metrics based on passive Hester-Dendy artificial substrate samplers differed greatly from active sampling methods (i.e., using nets) but represented abiotic conditions well in both ROR and RF sites. Although metric values were similar across certain sampling methods, the metrics significantly correlated with abiotic variables varied among methods and between ROR and RF sites. These results emphasize that methods are not interchangeable, and the ability to detect certain stressors depends on sampling method.
The United States Environmental Protection Agency-National Exposure Research Laboratory's (USEPA-NERL) dietary exposure research program investigates the role of diet, including drinking water, as a potential pathway of human exposure to environmental contaminants. A primary program goal is to establish measurement methods for ingestion that are consistent with approaches used by the USEPA to measure inhalation and dermal exposures, and, hence, total exposure. Research has focused on developing and field-testing measurement methods for personal dietary monitoring, known as duplicate-diet methodology, and on the methods to support analyses of environmental contaminants in foods and beverages. Guidance for measuring personal dietary exposure has been developed for the researcher performing measurements in which there is an established or potential route of exposure to environmental contaminants from foods consumed. Useful information for other types of dietary exposure assessment can be found in existing food consumption and food residue databases. Several of the major food databases have been integrated into an exposure model that provides estimates of potential dietary exposure and identifies potentially highly exposed people for guidance in exposure monitoring. Another component of this research program explores priority, diet-related issues to identify and reduce exposures from foods and beverages. The methods of preparing mercury-contaminated fish by Native Americans and children exposed to lead-laden environments are currently under investigation. Other research is designed to improve our understanding of the process of excess food contamination and the reduction of dietary exposure. Additional research needs are summarized. An overview of the USEPA-NERL dietary exposure program is presented and research discussed in this paper is described in the following papers in this issue.
Chronic inhalation of diesel exhaust (DE) causes lung tumors in rats; epidemiologic studies suggest that DE may be a potential human carcinogen. We compared the DE unit risks for human lung cancer as derived by Smith and Stayner (1991), Hattis and Silver (1992), Pepelko and Chen (1993), California Environmental Protection Agency, Office of Environmental Health Hazard Assessment (1994), and the U.S. Environmental Protection Agency (USEPA) (1994). All five sets of authors used identical rat bioassay data (Mauderly et al., 1987). Although different in detail, the dose-response models were uniformly linear and nonthreshold. However, each set of authors chose a different approach in relating the rat data to DE unit risk in humans. The predicted unit risks for continuous lifetime exposure to 1 microgram/m3 DE differed by an 80-fold factor between the highest [8 x 10(-4), Hattis and Silver] and the lowest [0.1 x 10(-4), Pepelko and Chen]. The choice of dose-input parameters and how each group treated particle overload were the major factors affecting the different risk estimates. Several unanswered questions undermine the current use of the rat bioassay for DE risk assessment: (1) Differences in emission products and exposure scenarios between laboratory studies and human exposure, (2) occurrence of an apparent threshold in the rat-lung-tumor response, (3) uncertainty as to the appropriate lung-dose metric and its low-dose extrapolation, (4) the role of lung overload, and (5) the cause of species-specific biological susceptibility.
To select a tentative standard method for detection of viruses in sludge the American Society for Testing and Materials D19:24:04:04 Subcommittee Task Group initiated round robin comparative testing of two procedures that, after initial screening of several methodologies, were found to meet the basic criteria considered essential by the task group. Eight task group member laboratories agreed to perform round robin testing of the two candidate methods, namely, The Environmental Protection Agency or low pH-AlCl3 method and the Glass or sonication-extraction method. Five different types of sludge were tested. For each particular type of sludge, a single laboratory was designated to collect the sludge in a single sampling, make samples, and ship it to the participating laboratories. In most cases, participating laboratories completed all the tests within 48 h of sample arrival. To establish the reproducibility of the methods, each laboratory tested each sludge sample in triplicate for the two candidate virus methods. Each processed sludge sample was quantitatively assayed for viruses by the procedures of each individual round robin laboratory. To attain a more uniform standard of comparison, a sample of each processed sample from all laboratories was reassayed with one cell line and passage number by a single laboratory (Environmental Protection Agency Environmental Monitoring and Support Laboratory, Cincinnati, Ohio). When the data were statistically analyzed, the Environmental Protection Agency method was found to yield slightly higher virus recoveries for all sludge types, except the dewatered sludge. The precisions of both methods were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)
Microorganisms are sensitive to heavy metal pollution as are other components of the biota. However, most studies on the interactions between microbes and heavy metals have been conducted in synthetic media or in altered (e.g., sterilized) environmental samples and usually have used only single species. Few studies have evaluated the effects of heavy metals on the activities of natural heterogeneous microbial populations, both autotrophic and heterotrophic, in terrestrial and aquatic environments. These latter studies have shown that heavy metals inhibit primary productivity, nitrogen fixation, the mineralization of carbon, nitrogen, sulfur, and phosphorus, litter decomposition, and enzyme synthesis and activity in soils, sediments, and surface waters. The potential adverse effects of heavy metals on such microbe-mediated ecologic processes need to be incorporated into the methodologies used by regulatory agencies, such as the U.S. Environmental Protection Agency, to prepare environmental risk assessments which, in turn, are used to formulate environmental criteria, such as the Water Quality Criteria, and to evaluate the safety to the environment of exposure to "new chemical substances," as mandated by the U.S. Toxic Substances Control Act of 1976. To provide appropriate data that can be assimilated into regulatory policy, it is essential that microbial ecotoxicity tests be standardized, are neither costly nor difficult to train personnel to conduct, and produce data that can be quantitated.
After an extensive review and assessment of the scientific evidence on the respiratory health effects of passive smoking, the U.S. Environmental Protection Agency has determined that the widespread exposure to environmental tobacco smoke in the United States presents a serious and substantial public health impact. The Environmental Protection Agency concluded that environmental tobacco smoke causes lung cancer in adult nonsmokers and increases the risk for a variety of noncancer respiratory disorders, especially in children. This article reviews evidence presented in the Environmental Protection Agency's 1992 report on the respiratory health effects of passive smoking and responds to critical allegations levied by Gio Gori in his article "Science, policy, and ethics: the case of environmental tobacco smoke", appearing in the same issue of this journal. Several recent studies appearing since the cutoff date for inclusion in the EPA report are also discussed.
In recent years there has been a startling rise in the issuance of fish consumption advisories. Unfortunately, compliance by the public is often low. Low compliance can be due to a number of factors, including confusion over the meaning of advisories, conflicting advisories issued by different agencies, controversies involving health benefits versus the risks from consuming fish, and an unwillingness to act on the advisories because of personal beliefs. In some places, such as along the Savannah River, one state (South Carolina) had issued a consumption advisory while the other (Georgia) had not, although at present, both states now issue consumption advisories for the Savannah River. Herein we report on the development of a fish fact sheet to address the confusing and conflicting information available to the public about consuming fish from the Savannah River. The process involved interviewing fishers to ascertain fishing and consumption patterns, evaluating contaminant levels and exposure pathways, discussing common grounds for the provision of information, and consensus-building among different regulatory agencies (US Environmental Protection Agency, South Carolina Department of Health and Environmental Control, Georgia Department of Natural Resources) and the Department of Energy. Consensus, a key ingredient in solving many different types of "commons" problems, was aided by an outside organization, the Consortium for Risk Evaluation with Stakeholder Participation (CRESP). The initial role for CRESP was to offer scientific data as a basis for groups with different assumptions about risks to reach agreement on a regulatory response action. The process was an example of how credible science can be used to implement management and policies and provide a basis for consensus-building on difficult risk communication issues. The paper provides several lessons for improving the risk process from stakeholder conflicts, through risk assessment, to risk management. It also suggests that consensus-building and risk communication are continuing processes that involve assimilation of new information on contaminants and food-chain processes, state and federal law, public policy, and public response.
Establishing the credibility of existing data is an ongoing issue, particularly when the data sets are to be used for a secondary purpose, i.e., not the original reason for which they were collected. If the secondary purpose is similar to the primary purpose, the potential user may have little difficulty establishing credibility since the acceptance criteria for both purposes should be similar. If the secondary purpose is different, then data credibility may be more difficult to establish because the experiment generating the data may not have been conducted optimally for the secondary purpose and all of the necessary quality assurance data ("metadata") may not have been collected. In either case, a process will be required to determine the acceptability of the data. For this reason, at the time the U.S. Environmental Protection Agency (EPA) Environmental Technology Verification (ETV) program was established, similar certification and verification programs run by states or foreign countries routinely used existing data sets, for cost reasons, rather than generate new data by testing. The issue of whether existing data could be used in the ETV program immediately surfaced. In response, a policy and a process that addressed existing data were written and published in Appendix C of the ETV Quality and Management Plan (Hayes et al., 1998). This paper discusses how the ETV program determines the credibility of existing data used to verify the performance of environmental technologies.
From 1993 through 1998, Wedding or Graseby high-volume PM10 samplers were collocated with tapered element oscillating microbalance (TEOM) samplers at three sites at Owens Lake, CA. The study area is heavily impacted by windblown dust from the dry Owens Lake bed, which was exposed as a result of water diversions to the city of Los Angeles. A dichotomous (dichot) sampler and three collocated Partisol samplers were added in 1995 and 1999, respectively. U.S. Environmental Protection Agency (EPA) operating procedures were followed for all samplers, except for a Wedding sampler that was not cleaned for the purpose of this study. On average, the TEOM and Partisol samplers agreed to within 6%, and the dichot, Graseby, and Wedding samplers measured lower PM10 concentrations by about 10, 25, and 35%, respectively. Surprisingly, the "clean" Wedding sampler consistently measured the same concentration as the "dirty" Wedding sampler through 85 runs without cleaning. The finding that the Graseby and Wedding high-volume PM10 samplers read consistently lower than the TEOM, Partisol, and dichot samplers at Owens Lake is consistent with PM10 sampler comparisons done in other fugitive dust areas, and with wind tunnel tests showing that sampler cut points can be significantly lower than 10 microns under certain conditions. However, these results are opposite of the bias found for TEOM samplers in areas that have significant amounts of volatile particles, where the TEOM reads low due to the vaporization of particles on the TEOM's heated filter. Coarse particles like fugitive dust are relatively unaffected by the filter temperature. This study shows that in the absence of volatile particles and in the presence of fugitive dust, a different systematic bias of up to 35% exists between samplers using dichot inlets and high-volume samplers, which may cause the Graseby and Wedding PM10 samplers to undermeasure PM10 by up to 35% when the PM10 is predominantly from coarse particulate sources.
In March of 1999, the Waste Isolation Pilot Plant (WIPP) in southeast New Mexico, the world's first deep geological repository for radioactive materials, began receiving defense-related transuranic waste. The WIPP was designed and constructed by the U.S. Department of Energy, but critical to its opening was certification by the U.S. Environmental Protection Agency that the repository complies with the radioactive waste disposal regulations set forth as environmental radiation protection standards (40 CFR Part 191) and compliance criteria (40 CFR Part 194). This paper provides a summary of the regulatory process, including the Environmental Protection Agency's waste containment, groundwater protection, and individual dose regulations for the WIPP; the Department of Energy's performance assessment and the other parts of its compliance certification application; and the Environmental Protection Agency's review and analysis of the compliance certification application and related documentation.