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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: A cross-platform microarray strategy was used to assess the profile of human spermatozoal transcripts from fertile males who had fathered at least one child compared to teratozoospermic individuals and revealed the transcriptional perturbation common to the affected individuals.
Abstract: We are coming to appreciate that at fertilization human spermatozoa deliver the paternal genome alongside a suite of structures, proteins and RNAs. Although the role of some of the structures and proteins as requisite elements for early human development has been established, the function of the sperm-delivered RNAs remains a point for discussion. The presence of RNAs in transcriptionally quiescent spermatozoa can only be derived from transcription that precedes late spermiogenesis. A cross-platform microarray strategy was used to assess the profile of human spermatozoal transcripts from fertile males who had fathered at least one child compared to teratozoospermic individuals. Unsupervised clustering of the data followed by pathway and ontological analysis revealed the transcriptional perturbation common to the affected individuals. Transcripts encoding components of various cellular remodeling pathways, such as the ubiquitin-proteosome pathway, were severely disrupted. The origin of the perturbation could be traced as far back as the pachytene stage of spermatogenesis. It is anticipated that this diagnostic strategy will prove valuable for understanding male factor infertility.

234 citations

Journal ArticleDOI
TL;DR: The results indicated that no species was consistently most sensitive, and that a suite of aquatic plant test species may be needed to perform accurate risk assessments of herbicides.
Abstract: This data relates to the relative sensitivity of five species of aquatic macrophytes and six species of algae to four commonly used herbicides (atrazine, metribuzin, alachlor, and metoachlor). Toxicity tests consisted of 96 hour (duckweed and algae) or 14 day (submerged macrophytes) static exposures. The triazine herbicides (atrazine and metribuzin) were significantly more toxic to aquatic plants than were the acetanilide herbicides (alachlor and metolachlor). Toxicity studies ranked metribuzin > atrazine > alachlor > metolachlor in decreasing order of overall toxicity to aquatic plants. Relative sensitivities of macrophytes to thse herbicides decreased in the order of Ceratophyllum > Najas > Elodea > Lemna > Myriophyllum. Relative sensitivities of algae to herbicides decreased in the order of Selenastrum > Chlorella > Chlamydomonas > Microcystis > Scenedesmus > Anabaena. Algae and macrophytes were of similar overall sensitivities to herbicides. Data indicated that Selenastrum, a commonly tested green alga, was generally more sensitive compared to other plant species. Lemna minor, a commonly tested floating vascular plant, was of intermediate sensitivity, and was fivefold less sensitive than Ceratophyllum, which was the most sensitive species tested. The results indicated that no species was consistently most sensitive, and that a suite of aquatic plant test species may be needed to perform accurate risk assessments of herbicides.

234 citations

Journal ArticleDOI
TL;DR: Suggestive results support a previously reported finding of an association between ozone exposure and pulmonary artery and valve defects and evidence that air pollution exposure influences the risk of oral clefts was limited.
Abstract: A population-based case-control study investigated the association between maternal exposure to air pollutants, carbon monoxide, nitrogen dioxide, ozone, sulfur dioxide, and particulate matter <10 microm in aerodynamic diameter during weeks 3-8 of pregnancy and the risk of selected cardiac birth defects and oral clefts in livebirths and fetal deaths between 1997 and 2000 in seven Texas counties Controls were frequency matched to cases on year of birth, vital status, and maternal county of residence at delivery Stationary monitoring data were used to estimate air pollution exposure Logistic regression models adjusted for covariates available in the vital record When the highest quartile of exposure was compared with the lowest, the authors observed positive associations between carbon monoxide and tetralogy of Fallot (odds ratio = 204, 95% confidence interval: 126, 329), particulate matter <10 microm in aerodynamic diameter and isolated atrial septal defects (odds ratio = 227, 95% confidence interval: 143, 360), and sulfur dioxide and isolated ventricular septal defects (odds ratio = 216, 95% confidence interval: 151, 309) There were inverse associations between carbon monoxide and isolated atrial septal defects and between ozone and isolated ventricular septal defects Evidence that air pollution exposure influences the risk of oral clefts was limited Suggestive results support a previously reported finding of an association between ozone exposure and pulmonary artery and valve defects

234 citations

Journal ArticleDOI
TL;DR: Predicting the potential toxicity of emerging nanoparticles will require hypothesis-driven research that elucidates how physicochemical parameters influence toxic effects on biological systems, and a battery of tests should be developed to uncover particularly hazardous properties.
Abstract: Close to 400 manufacturer-identified nanotechnology-based consumer products are now on the market (Woodrow Wilson International Center for Scholars 2007). Using increasingly sophisticated levels of control over the assembly of atoms and molecules to form substances and devices, nanotech companies are exploiting the size-dependent properties of nanostructured materials for applications ranging from cosmetics to fuel cells (Colvin 2003). Yet our understanding of the potential toxicity of nanoparticles remains rudimentary (Colvin 2003; Oberdorster et al. 2005b). To determine whether the unique chemical and physical properties of new nanoparticles result in specific toxicologic properties, the nanotechnology community needs new ways of evaluating hazard and ultimately assessing risk (Nel et al. 2006). These new strategies must also consider the complexities inherent to studies of chemical mixtures. This workshop’s assessment of the novel aspects of nanotoxicology built on knowledge gained from prior workshops. In 2004, scientists from many different areas of research came together in Gainesville, Florida, to discuss the emerging field of nanotoxicology (Bucher et al. 2004). They described the challenges facing toxicologists in rigorously characterizing the new materials and in understanding how nanostructures might differentially influence toxicity. This theme was further elaborated in a seminal article by Oberdorster et al. (2005a), which provides a general framework for evaluating the toxicity of engineered nanoparticles. More detailed questions regarding exactly how to evaluate the potential health impact of engineered nanoparticles remain. This report captures some of the critical information that is still needed to understand the human health impact of engineered nanoparticles and defines mechanisms to begin to acquire this information. Building on the insight from those previous meetings and published articles—that the structure of nanoparticles brings many new challenges to toxicological evaluation—workshop participants were asked to identify both factors that make nanoparticles different and information specific to these differences that is needed to assess nanoparticle hazards. The group was further charged with making recommendations on how to gather and use that additional information to evaluate health hazards associated with these scale-specific properties. Because of the short duration of this workshop, the scope was limited to consideration of toxic properties of nanoparticles. A full evaluation of human health risks will require development of sufficient techniques for assessing exposure to nanoparticles in addition to consideration of toxicity. E. Silbergeld of Johns Hopkins University opened the workshop with a presentation that explored ways of thinking about and evaluating the potential hazards of nanoparticles. She emphasized focus on the nanoscale interactions that take place in the normal functioning of biological systems in order to understand the positive and negative effects that engineered nanoparticles could have on humans. For example, because the immune system functions through nanoscale intercellular communications, Lynch et al. (2006) hypothesized that engineered nanoparticles can disrupt these processes with deleterious end results. Specifically, they considered unique interactions between native proteins and the highly curved surfaces of nanoparticles, speculating that the protein shape could be modified after binding. This deformation could expose amino acid residues that are normally buried in the core of the protein, and the immune system would then recognize these newly exposed residues as “cryptic epitopes” and mount an unwanted immune response. A 2005 study by Zhao et al. (2005) predicted that DNA repair, another vital biological system that operates at the nanoscale, is also susceptible to modification by nanoparticles. Specifically, this study found through computer modeling that the association in water between C60 and DNA is stronger than the association between two C60 molecules. Therefore, when DNA is damaged, fullerenes can occupy the damaged site, possibly impeding the self-repairing processes of the double-strand DNA and thus negatively impacting the structure, stability, and biological functions of DNA molecules. These unique interactions between nanoparticles and biological systems afford great promise for medicinal applications, but the unintended consequences could be harmful. We know, for instance, that natural and unintentionally produced ultrafine particulate matter, which is in the same size range as engineered nanoparticles, can carry a broad range of compounds, including polycyclic aromatic hydrocarbons, endotoxin, metals, and other toxic chemicals. These complexes can then damage biological systems (Penn et al. 2005; Schwarze et al. 2006). Gutierrez-Castillo et al. (2006) found that particulate matter with chemicals adsorbed to the surface can damage DNA. These examples suggest that the myriad possible interactions between nanoparticles and harmful environmental chemicals may lead to unique exposures and health risks. Conventional knowledge about exposure assessment, fate and transport, and current computer models is not necessarily applicable to nanoparticles. But alternative methods such as toxicogenomic technologies, lower-order animal and in vitro testing, and ultimately the development of structure activity models could prove useful, providing more rapid testing than traditional animal toxicology tests and allowing for explicit experimental design based on mechanism. The development of alternative methods is an ambitious but necessary goal if the large and growing numbers of nanoparticles are to be adequately assessed for toxicity. Silbergeld ended her presentation with a charge for the group: to frame its dialogue both to inform the industry on how to look before leaping into the production of new nanoparticles and to provide guidance for those who have already taken that leap.

234 citations

Journal ArticleDOI
TL;DR: This study shows that phototoxicity can occur in marine waters to marine species and the occurrence of oil in marine Waters presents the additional risk of photot toxicity not routinely assessed for during oil spills.
Abstract: Phototoxicity resulting from photoactivated polycyclic aromatic hydrocarbons (PAHs) has been reported in the literature for a variety of freshwater organisms. The magnitude of increase in PAH toxicity often exceeds a factor of 100. In the marine environment phototoxicity to marine organisms has not been reported for individual or complex mixtures of PAHs. In this study, larvae and juveniles of the bivalve, Mulinia lateralis, and juveniles of the mysid shrimp, Mysidopsis bahia, were exposed to individual known phototoxic PAHs (anthracene, fluoranthene, pyrene), as well as the water-accommodated fractions of several petroleum products (Fuel Oil #2, Arabian Light Crude, Prudhoe Bay Crude, Fuel Oil #6) containing PAHs. Phototoxicity of individual PAHs was 12 to >50,000 times that of conventional toxicity. Three of the petroleum products demonstrated phototoxicity while the lightest product, Fuel Oil #2, was not phototoxic at the concentrations tested. The phototoxicity of petroleum products appears to be dependent on the composition and concentrations of phototoxic PAHs present: lighter oils have fewer multiple aromatic ring, phototoxic compounds while heavier oils have higher levels of these types of molecules. This study shows that phototoxicity can occur in marine waters to marine species. Further, the occurrence of oil in marine waters presents the additional risk of phototoxicity not routinely assessed for during oil spills.

233 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