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Institution

United States Environmental Protection Agency

GovernmentWashington D.C., District of Columbia, United States
About: United States Environmental Protection Agency is a government organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Population & Environmental exposure. The organization has 13873 authors who have published 26902 publications receiving 1191729 citations. The organization is also known as: EPA & Environmental Protection Agency.


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Journal ArticleDOI
TL;DR: By providing a systematic approach to using MOA data, the HRF offers a new tool for the scientific community's overall effort to enhance the predictive power, reliability and transparency of cancer risk assessment.
Abstract: The human relevance framework (HRF) outlines a four-part process, beginning with data on the mode of action (MOA) in laboratory animals, for evaluating the human relevance of animal tumors. Drawing on U.S. EPA and IPCS proposals for animal MOA analysis, the HRF expands those analyses to include a systematic evaluation of comparability, or lack of comparability, between the postulated animal MOA and related information from human data sources. The HRF evolved through a series of case studies representing several different MOAs. HRF analyses produced divergent outcomes, some leading to complete risk assessment and others discontinuing the process, according to the data available from animal and human sources. Two case examples call for complete risk assessments. One is the default: When data are insufficient to confidently postulate a MOA for test animals, the animal tumor data are presumed to be relevant for risk assessment and a complete risk assessment is necessary. The other is the product of a data-based finding that the animal MOA is relevant to humans. For the specific MOA and endpoint combinations studied for this article, full risk assessments are necessary for potentially relevant MOAs involving cytotoxicity and cell proliferation in animals and humans (Case Study 6, chloroform) and formation of urinary-tract calculi (Case Study 7, melamine). In other circumstances, when data-based findings for the chemical and endpoint combination studied indicate that the tumor-related animal MOA is unlikely to have a human counterpart, there is little reason to continue the risk assessment for that combination. Similarly, when qualitative considerations identify MOAs specific to the test species or quantitative considerations indicate that the animal MOA is unlikely to occur in humans, such hazard findings are generally conclusive and further risk assessment is not necessary for the endpoint-MOA combination under study. Case examples include a tumor-related protein specific to test animals (Case Study 3, d-limonene), the tumor consequences of hormone suppression typical of laboratory animals but not humans (Case Study 4, atrazine), and chemical-related enhanced hormone clearance rates in animals relative to humans (Case Study 5, phenobarbital). The human relevance analysis is highly specific for the chemical-MOA-tissue-endpoint combination under analysis in any particular case: different tissues, different endpoints, or alternative MOAs for a given chemical may result in different human relevance findings. By providing a systematic approach to using MOA data, the HRF offers a new tool for the scientific community's overall effort to enhance the predictive power, reliability and transparency of cancer risk assessment.

410 citations

Journal ArticleDOI
TL;DR: In this article, the authors update and reevaluate the scientific information on the distribution, history, and causes of continental shelf hypoxia that supports the 2001 Action Plan for Reducing, Mitigating, and Controlling Hypoxia in the Northern Gulf of Mexico (Mississippi River/Gulf of Mexico Watershed Nutrient Task Force 2001).
Abstract: We update and reevaluate the scientific information on the distribution, history, and causes of continental shelf hypoxia that supports the 2001 Action Plan for Reducing, Mitigating, and Controlling Hypoxia in the Northern Gulf of Mexico (Mississippi River/Gulf of Mexico Watershed Nutrient Task Force 2001), incorporating data, publications, and research results produced since the 1999 integrated assessment. The metric of mid-summer hypoxic area on the LouisianaTexas shelf is an adequate and suitable measure for continued efforts to reduce nutrients loads from the Mississippi River and hypoxia in the northern Gulf of Mexico as outlined in the Action Plan. More frequent measurements of simple metrics (e.g., area and volume) from late spring through late summer would ensure that the metric is representative of the system in any given year and useful in a public discourse of conditions and causes. The long-term data on hypoxia, sources of nutrients, associated biological parameters, and paleoindicators continue to verify and strengthen the relationship between the nitratenitrogen load of the Mississippi River, the extent of hypoxia, and changes in the coastal ecosystem (eutrophication and worsening hypoxia). Multiple lines of evidence, some of them representing independent data sources, are consistent with the big picture pattern of increased eutrophication as a result of long-term nutrient increases that result in excess carbon production and accumulation and, ultimately, bottom water hypoxia. The additional findings arising since 1999 strengthen the science supporting the Action Plan that focuses on reducing nutrient loads, primarily nitrogen, through multiple actions to reduce the size of the hypoxic zone in the northern Gulf of Mexico.

410 citations

Journal ArticleDOI
TL;DR: A summary of the initial, proof of concept, Phase I of ToxCast that has laid the groundwork for the next phases and future directions of the program is provided.
Abstract: The field of toxicology is on the cusp of a major transformation in how the safety and hazard of chemicals are evaluated for potential effects on human health and the environment. Brought on by the recognition of the limitations of the current paradigm in terms of cost, time, and throughput, combined with the ever increasing power of modern biological tools to probe mechanisms of chemical–biological interactions at finer and finer resolutions, 21st century toxicology is rapidly taking shape. A key element of the new approach is a focus on the molecular and cellular pathways that are the targets of chemical interactions. By understanding toxicity in this manner, we begin to learn how chemicals cause toxicity, as opposed to merely what diseases or health effects they might cause. This deeper understanding leads to increasing confidence in identifying which populations might be at risk, significant susceptibility factors, and key influences on the shape of the dose–response curve. The U. S. Environmental Pro...

410 citations

Journal ArticleDOI
TL;DR: In this article, the authors report the presence of PFECAs in the Cape Fear River watershed, their fate in water treatment processes, and their adsorbability on powdered activated carbon (PAC).
Abstract: Long-chain per- and polyfluoroalkyl substances (PFASs) are being replaced by short-chain PFASs and fluorinated alternatives. For ten legacy PFASs and seven recently discovered perfluoroalkyl ether carboxylic acids (PFECAs), we report (1) their occurrence in the Cape Fear River (CFR) watershed, (2) their fate in water treatment processes, and (3) their adsorbability on powdered activated carbon (PAC). In the headwater region of the CFR basin, PFECAs were not detected in raw water of a drinking water treatment plant (DWTP), but concentrations of legacy PFASs were high. The U.S. Environmental Protection Agency’s lifetime health advisory level (70 ng/L) for perfluorooctanesulfonic acid and perfluorooctanoic acid (PFOA) was exceeded on 57 of 127 sampling days. In raw water of a DWTP downstream of a PFAS manufacturer, the mean concentration of perfluoro-2-propoxypropanoic acid (PFPrOPrA), a replacement for PFOA, was 631 ng/L (n = 37). Six other PFECAs were detected, with three exhibiting chromatographic peak ar...

410 citations

Journal ArticleDOI
TL;DR: The significant effect of maternal age and birth weight after adjusting for other confounding variables suggests that the in utero environment may be an important determinant of asthma.
Abstract: This study analyzes data from the Second National Health and Nutritional Examination Survey to determine whether black children are more likely to have asthma or wheeze, even after adjusting for environmental and socioeconomic exposures. For children 6 months to 11 yr of age, the unadjusted prevalence for asthma was 3.0% among white children and 7.2% among blacks; prevalence of frequent wheeze was 6.2% among whites and 9.3% among blacks. In a logistic regression model including race, age, and sex, the relative odds (RO) of asthma for black children as compared to white children were 2.5 (95% confidence interval [CI], 1.9 to 3.4). Other predictors of asthma in a stepwise logistic regression included age, sex (boys versus girls, RO = 1.4), younger maternal age (2 standard deviation [SD] drop in age, RO = 1.4), residence in the central city (RO = 1.6), and family income (RO for the lowest versus highest tertile, RO = 1.7). After adjusting for these risk factors, age and sex, black children still had a 1.7 RO...

410 citations


Authors

Showing all 13926 results

NameH-indexPapersCitations
Joel Schwartz1831149109985
Timothy A. Springer167669122421
Chien-Jen Chen12865566360
Matthew W. Gillman12652955835
J. D. Hansen12297576198
Dionysios D. Dionysiou11667548449
John P. Giesy114116262790
Douglas W. Dockery10524457461
Charles P. Gerba10269235871
David A. Savitz9957232947
Stephen Polasky9935459148
Judith C. Chow9642732632
Diane R. Gold9544330717
Scott L. Zeger9537778179
Rajender S. Varma9567237083
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202356
202279
2021780
2020787
2019852
2018929