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PubMed1984

The genotoxic/epigenetic distinction: relevance to cancer policy.

Should federal agencies use separate, less stringent guidelines for regulating epigenetic or nongenotoxic carcinogens on the assumption that thresholds are likely to exist for these agents? This article reviews recent initiatives by the Environmental Protection Agency that either propose or informally adopt this approach in light of responses from the scientific community and a review of the recent literature. Relevant background is provided by current research concerning the role of chromosomal damage and oncogene activation in carcinogenesis along with findings that classical promoters or "epigenetic" agents can induce both DNA damage and chromosomal rearrangements. The conclusion is that such a revision of cancer policy is not now supported by available scientific data concerning chemical carcinogenesis.

Animals↗
PubMed1999

Quantification of polycyclic aromatic hydrocarbons in soil at McMurdo Station, Antarctica.

Polycyclic aromatic hydrocarbons (PAHs) are a group of compounds that have attracted much attention over the past several years. The United States Environmental Protection Agency (USEPA) has identified numerous PAHs as known or probable human carcinogens. The quantity of PAHs in the environment has dramatically increased, with the majority emitted from fossil fuel combustion sources. Surface soil samples were collected at McMurdo Station, Antarctica (77 degrees 51S, 166 degrees 41E), during peak summer activity and analyzed for PAHs. PAHS were detected at several locations, with maximum concentrations for naphthalene, acenaphthene, acenaphthylene, and fluoranthene at 27,000, 17,800, 15,700 and 13,300 mg/kg, respectively. Results suggest anthropogenic activities may be contributing to increased levels of PAHs present in McMurdo soils.

Antarctic Regions↗
PubMed1996

A Monte Carlo procedure for the construction of complementary cumulative distribution functions for comparison with the EPA release limits for radioactive waste disposal.

A Monte Carlo procedure for the construction of complementary cumulative distribution functions (CCDFs) for comparison with the U.S. Environmental Protection Agency (EPA) release limits for radioactive waste disposal (40 CFR 191, Subpart B) is described and illustrated with results from a recent performance assessment (PA) for the Waste Isolation Pilot Plant (WIPP). The Monte Carlo procedure produces CCDF estimates similar to those obtained with importance sampling in several recent PAs for the WIPP. The advantages of the Monte Carlo procedure over importance sampling include increased resolution in the calculation of probabilities for complex scenarios involving drilling intrusions and better use of the necessarily limited number of mechanistic calculations that underlie CCDF construction.

Monte Carlo Method↗
PubMed1992

EPA priorities for biologic markers research in environmental health.

Recent advances in molecular and cellular biology allow for measurement of biologic events or substances that may provide markers of exposure, effect, or susceptibility in humans. The application of these new and emerging techniques to environmental health offers the possibility of significantly reducing the uncertainties that traditionally hamper risk assessments. The U.S. Environmental Protection Agency (EPA) health research program emphasizes the validation of appropriate biologic markers and their application to high-priority Agency issues. The rationale for EPA's biomarker research program is presented, and future research directions are discussed. Exposure biomarkers will receive most of the research emphasis in the near term, particularly body burden indicators of exposure to high-priority chemicals, such as benzene, ozone, selected heavy metals, and organophosphate pesticides. Research on effects biomarkers will attempt to validate the relationship between the observed biological effects and adverse health consequences in humans, especially for cancer, pulmonary toxicity, immunotoxicity, and reproductive/developmental toxicity.

Animals↗
PubMed2001

Developing seasonal ammonia emission estimates with an inverse modeling technique.

Significant uncertainty exists in magnitude and variability of ammonia (NH3) emissions, which are needed for air quality modeling of aerosols and deposition of nitrogen compounds. Approximately 85% of NH3 emissions are estimated to come from agricultural nonpoint sources. We suspect a strong seasonal pattern in NH 3 emissions; however, current NH3 emission inventories lack intra-annual variability. Annually averaged NH 3 emissions could significantly affect model-predicted concentrations and wet and dry deposition of nitrogen-containing compounds. We apply a Kalman filter inverse modeling technique to deduce monthly NH3 emissions for the eastern U.S. Final products of this research will include monthly emissions estimates from each season. Results for January and June 1990 are currently available and are presented here. The U.S. Environmental Protection Agency (USEPA) Community Multiscale Air Quality (CMAQ) model and ammonium (NH4+) wet concentration data from the National Atmospheric Deposition Program (NADP) network are used. The inverse modeling technique estimates the emission adjustments that provide optimal modeled results with respect to wet NH4+ concentrations, observational data error, and emission uncertainty. Our results suggest that annual average NH 3 emissions estimates should be decreased by 64% for January 1990 and increased by 25% for June 1990. These results illustrate the strong differences that are anticipated for NH3 emissions.

Agriculture↗
PubMedDate not supplied

Enumeration of Cryptosporidium spp. in water with US EPA method 1622, USA.

The occurrence of Cryptosporidium parvum or other pathogenic Cryptosporidium species in water must be known in order to assess risk and determine the treatment needed to reduce Cryptosporidium oocysts to acceptable levels in finished drinking water. Because Cryptosporidium oocyst occurrence may be sparse, methods must concentrate a large volume of water and correctly identify oocysts in the concentrate. The U.S. Environmental Protection Agency Information Collection Rule (ICR) protozoan method gives low and variable recoveries of Cryptosporidium oocysts, making risk assessment difficult. Therefore, a method giving better oocyst recovery and more consistent results was needed. Method 1622 was developed with existing materials and procedures, and improvements were made in filtration, cleanup, and detection. Absolute porosity filters were used, with cleanup by immunomagnetic separation and detection by direct fluorescent antibody stain with 4',6-diamidino-2-phenylindole (DAPI) staining for additional cell structures. Both the level and consistency of oocyst recovery were improved compared to recovery with the ICR method.

Animals↗
PubMed2004

Resolving conflict and building cooperation in the National Estuary program.

Since its beginning in 1987, researchers and policymakers have touted the US Environmental Protection Agency National Estuary program (NEP) as one of the leading examples of collaborative institutions designed to resolve conflict and build cooperation at the watershed level. Using the NEP as an example, I summarize the advantages and disadvantages of collaborative institutions. Using data gathered from focused surveys of policy elites in 22 estuaries, I estimate statistical models that show the NEP does a better job of resolving conflict and building project-level cooperation than similar estuaries without the NEP. I also describe the activities of the NEP mentioned by respondents as contributing to this outcome.

Conflict of Interest↗
PubMed1994

Discrepancies in committed effective dose equivalents calculated using U.S. Nuclear Regulatory Commission Regulatory Guide 8.34.

Calculations of Committed Effective Dose Equivalent (CEDE) due to inhalation using four of the five methods suggested in the United States Nuclear Regulatory Commission Regulatory Guide 8.34 (1992a) were performed to determine if any significant differences in the calculated value of the CEDE exist for typical power plant radionuclides. These four methods included dose conversion factors from the United States Environmental Protection Agency Federal Guidance Report No. 11 (Eckerman et al. 1988), Annual Limit on Intake, Derived Air Concentrations, and Weighted Committed Dose Equivalents from ICRP Publication 30 (1979). Of the 68 radionuclides included, 48 demonstrated significant differences of 20% or greater in the calculated CEDE values for the four methods used. The differences in calculated values for the CEDE can be explained by the varied use of the 10% Rule and by rounding of tabulated values for ALIs and DACs to one significant digit.

Government Agencies↗
PubMed2000

Air pollution. Evidence mounts that tiny particles can kill.

Four years ago, the U.S. Environmental Protection Agency (EPA) ignited a fire storm when it declared that tens of thousands of people were dying each year from breathing tiny particles of dust and soot--and issued tough new regulations to crack down on these pollutants. Industry groups and many scientists assailed the decision, arguing that the data underlying the new particulate matter standard were inconclusive at best, and industry took their case to court. Now, a long-awaited study, by a group widely perceived to be politically neutral, comes in solidly behind the earlier EPA decision and strongly implicates particles in excess deaths.

Air Pollutants↗
PubMedDate not supplied

A simple method for evaluating data from an interlaboratory study.

Large-scale laboratory- and method-performance studies involving more than about 30 laboratories may be evaluated by calculating the HORRAT ratio for each test sample (HORRAT = [experimentally found among-laboratories relative standard deviation] divided by [relative standard deviation calculated from the Horwitz formula]). The chemical analytical method is deemed acceptable per se if HORRAT approximately 1.0 (+/- 0.5). If HORRAT is > or approximately 2.0, the most extreme values are removed successively until an "acceptable" ratio is obtained. The laboratories responsible for the extreme values that are removed should examine their technique and procedures. If > or approximately 15% of the values have to be removed, the instructions and the methods should be examined. This suggested computation procedure is simple and does not require statistical outlier tables. Proposed action limits may be adjusted according to experience. Data supporting U.S. Environmental Protection Agency method 245.1 for mercury in waters (manual cold-vapor atomic absorption spectrometry), supplemented by subsequent laboratory-performance data, were reexamined in this manner. Method-performance parameters (means and among-laboratories relative standard deviations) were comparable with results from the original statistical analysis that used a robust biweight procedure for outlier removal. The precision of the current controlled performance is better by a factor of 4 than that of estimates resulting from the original method-performance study, at the expense of rejecting more experimental values as outliers.

Chemistry Techniques, Analytical↗
PubMed2006

Determination of perchlorate in drinking water by ion chromatography using macrocycle-based concentration and separation methods.

Macrocycle-based ion chromatography provides a convenient, reliable method for the determination of perchlorate ion, which is currently of great interest to the environmental community. This study shows that effective perchlorate determinations can be made using standard conductimetric detection by combining an 18-crown-6-based mobile phase with an underivatized reversed-phase mobile phase ion chromatography (MPIC) column. One unique feature of this method is the flexibility in column capacity that is achieved through simple variations in eluent concentrations of 18-crown-6 and KOH, facilitating the separation of target analyte anions such as perchlorate. Using a standard anion exchange column as concentrator makes possible the determination of perchlorate as low as 0.2 ug/L in low ionic strength matrices. Determination of perchlorate at the sub-ug/L level in pure water and in spiked local city hard water samples with high background ion concentrations can be achieved this way. However, like other IC techniques, this method is challenged to achieve analyses at the ug/L level in the demanding high ionic strength matrix described by the United States Environmental Protection Agency (EPA) (1,000 mg/L chloride, sulfate and carbonate). We approached this challenge by use of the Cryptand C1 concentrator column, provided by Dionex Corporation, to effectively preconcentrate perchlorate while reducing background ion concentrations in the high ionic strength matrix. The retention characteristics of the concentrator column were studied in order to maximize its effectiveness for perchlorate determinations. The method makes possible the determination of perchlorate at the 5 ug/L level in the highest ionic strength matrix described by the EPA.

Chromatography, Ion Exchange↗
PubMed1998

Lognormal distributions for skin area as a function of body weight.

This paper reanalyzes the dataset cited by the U.S. Environmental Protection Agency in its Exposure Factors Handbook that contains measurements of skin area, height, and body weight for 401 people spanning all stages of development. The reanalysis shows that a univariate model for total skin area as a function of body weight gives useful and practical results with little or no loss of reliability as compared to the Agency's bivariate model. This new result leads to a new method to develop Lognormal distributions for total skin area as a function of body weight alone.

Body Surface Area↗
PubMed1994

Evaluation of reduced protocols for carcinogenicity testing of chemicals: report of a joint EPA/NIEHS workshop.

The current U.S. Environmental Protection Agency (EPA) and other national/international guidelines specify the use of two species and two sexes rodents (usually the rat and the mouse) for carcinogenicity testing of chemicals. In view of the enormous number of chemicals to be tested, the high cost of testing, and the large number of animals used in the present protocol, many academic, industrial, and government authorities are examining the possibility of using a reduced protocol (less than two species and two sexes of rodents) for carcinogenicity testing of chemicals. The use of a reduced protocol offers many advantages as well as some disadvantages. To pursue further the potential implications and impacts of using a reduced protocol for carcinogenicity testing on the processes of hazard identification and risk assessment, a workshop entitled "Evaluation of Reduced Protocols for Carcinogenicity Testing of Chemicals" was held at the Embassy Suites Hotel in Alexandria, Virginia on September 22 and 23, 1992. It was cosponsored by EPA's Office of Prevention, Pesticides and Toxic Substances (OPPTS) and the National Toxicology Program of the National Institutes of Environmental Health Sciences (NTP/NIEHS) and attended by more than 60 participants from government, industry, academia, and the general public. The Expert Consensus Panel and most of the participants supported the use of reduced protocols in carcinogenicity testing. However, it was recognized that reduced protocols may not be appropriate for the testing of all chemicals and that additional analyses/data may be needed for selection of the most appropriate reduced protocol for certain chemicals/chemical classes.

Animals↗
PubMed1994

Development and impact of the Gene-Tox-Program, genetic activity profiles, and their computerized data bases.

This invited historical review traces the development and impact of two major data bases in the field of genetic toxicology. Discussed from a personal perspective are the Environmental Protection Agency (EPA) Gene-Tox Program and the EPA/International Agency for Research on Cancer Genetic Activity Profiles (GAPs) and their respective data bases. Whereas Gene-Tox was focused on the assessment of short-term tests and their role in predicting carcinogens and mutagens, GAPs and the GAP data base were designed specifically to aid in the evaluation of individual chemicals. Both data bases have been computerized. Gene-Tox is available on TOXNET and GAP is available in a personal computer format from the author. The Gene-Tox and GAP data bases appear to have had substantial impact, particularly on hazard identification activities in cancer risk assessment.

Carcinogenicity Tests↗
PubMed1996

Is ingested inorganic arsenic a "threshold" carcinogen?

Ingested inorganic arsenic (As) is known to be a human carcinogen. An intriguing question is whether there is a threshold for the carcinogenic effects of As, i.e., is there a level below which it does not induce the development of cancer(s)? This Roundtable will discuss the United States Environmental Protection Agency's As risk assessment using the Taiwan data from different viewpoints. It will also consider the hypothesis that there is a threshold for As and data for or against this hypothesis. For example, some scientists believe that epidemiological data cannot answer this question, while others feel that different study designs and larger sampling will provide adequate data. Reasons for each position are given. This Roundtable discussion demonstrates the controversy surrounding the use of the Taiwan data for risk assessment.

Arsenic Poisoning↗
PubMed1989

Summary of the 1989 EPA/A&WMA International symposium: measurement of toxic and related air pollutants.

A joint conference, for the fourth straight year cosponsored by the Air & Waste Management Association's TP-6, TP-7, and ITF-2 technical committees, and the Atmospheric Research and Exposure Assessment Laboratory of the U.S. Environmental Protection Agency, was held at Raleigh, North Carolina, May 2-5, 1989. The technical program consisted of 145 presentations, held in 14 separate technical sessions, on recent advances in the measurement and monitoring of toxic and related pollutants found in ambient and source atmospheres. Covering a wide range of measurement topics and superbly supported by 57 exhibitors of instrumentation and consulting services, the symposium was enthusiastically received by more than 700 attendees from the United States and other countries. This overview contains a selection of the highlights from the technical presentations. A synopsis of the keynote address to the symposium is also included.

Air Pollutants↗
PubMed2005

Use of ozone-depleting substances; removal of essential-use designations. Final rule.

The Food and Drug Administration (FDA) is amending its regulation on the use of ozone-depleting substances (ODSs) in self-pressurized containers to remove the essential-use designations for albuterol used in oral pressurized metered-dose inhalers (MDIs). Under the Clean Air Act, FDA, in consultation with the Environmental Protection Agency (EPA), is required to determine whether an FDA-regulated product that releases an ODS is an essential use of the ODS. Two albuterol MDIs that do not use an ODS have been marketed for more than 3 years. FDA has determined that the two non-ODS MDIs will be satisfactory alternatives to albuterol MDIs containing ODSs and is removing the essential-use designation for albuterol MDIs as of December 31, 2008. Albuterol MDIs containing an ODS cannot be marketed after this date.

Adrenergic beta-Agonists↗
PubMed1995

Survey of lead exposure around a closed lead smelter.

OBJECTIVE: To test the hypothesis that elevated lead in soil is positively correlated with blood lead (BPb) levels in children in an urban population surrounding a closed lead smelter, a US Environmental Protection Agency Superfund clean-up site was surveyed. METHOD: A total of 827 volunteers including 490 children under 6 years of age participated. A questionnaire was administered. Blood lead was determined as was lead content of samples of house dust, soil, paint, and water of the participants' homes. RESULTS: The arithmetic mean venous BPb in 490 children between 6 and 72 months of age was 6.9 micrograms/dL (0.33 mumol/L) range 0.7 to 40.2 micrograms/dL (0.03 to 1.94 mumol/L). The BPb of 78 (16%) children in this group was > or = 10 micrograms/dL (0.48 mumol/L). Based on multiple regression modeling, lead in house dust accounted for 18% of the variance in BPb. Lead in paint together with the condition of the house were the main contributors to the dust lead variance (26%) with soil lead accounting for an additional 6%. Lead in paint alone accounted for 3% of the BPb variance. Lead in paint together with the condition of the house accounted for 12% of BPb variance, and lead in soil accounted for an additional 3%. Factors other than environmental lead such as education of parents, household income, and behavior were associated with BPb levels. CONCLUSIONS: The mean BPb in children was below the present level of concern of the Centers for Disease Control and Prevention. Children with BPb of > or = 10 micrograms/L (0.48 mumol/L) tended to live in poorly maintained older houses. Based on these findings lead in soil and paint in well-maintained homes contributed little to the lead exposure of children.

Child, Preschool↗