United States Environmental Protection Agency

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.

Distribution of six virulence factors in Aeromonas species isolated from US drinking water utilities: a PCR identification.

Abstract: K. SEN AND M. RODGERS. 2004. Aims: To examine whether Aeromonas bacteria isolated from municipally treated water had virulence factor genes. Methods and Results: A polymerase chain reaction-based genetic characterization determined the presence of six virulence factors genes, elastase (ahyB), lipase (pla/lip/lipH3/alp-1) flagella A and B (flaA and flaB), the enterotoxins, act, alt and ast, in these isolates. New primer sets were designed for all the target genes, except for act. The genes were present in 88% (ahyB), 88% (lip), 59% (fla), 43% (alt), 70% (act) and 30% (ast) of the strains, respectively. Of the 205 isolates tested only one isolate had all the virulence genes. There was a variety of combinations of virulence factors within different strains of the same species. However, a dominant strain having the same set of virulence factors, was usually isolated from any given tap in different rounds of sampling from a single tap. Conclusions: These results show that Aeromonas bacteria found in drinking water possess a wide variety of virulence-related genes and suggest the importance of examining as many isolates as possible in order to better understand the health risk these bacteria may present. Significance and Impact of the Study: This study presents a rapid method for characterizing the virulence factors of Aeromonas bacteria and suggests that municipally treated drinking water is a source of potentially pathogenic Aeromonas bacteria.

Isolated wetlands and their functions: an ecological perspective

Abstract: The recent U.S. Supreme Court case of Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers (SWANCC) has had profound implications on the legal status of isolated wetlands. As a result, policymakers need ecological information on the definition and functions of isolated wetlands to respond to this decision. The term “isolated wetlands” is of fairly recent usage and has been poorly defined. In response, I recommend Tiner’s (2003b) definition as wetlands “that are completely surrounded by upland.” Isolation needs to be considered with respect to specific processes and functions. I suggest that isolation not be viewed discretely but be considered within an isolation-connectivity continuum. Isolation has a fundamental influence on the way water enters and leaves a wetland. This consequently affects any wetland function that depends on water as a vector (e.g., pollutant transport and certain types of dispersal). These wetlands can also have a high level of endemism, extensive plant zonation, and high biodiversity. Isolated wetlands, however, do not represent ecologically isolated habitat for many organisms. I conclude that the effect of isolation may not be as significant as the term “isolated wetlands” suggests: many of the biological features of isolated wetlands may result from environmental conditions that also occur in nonisolated wetlands. As a result of SWANCC, assessment methods are needed that can help regulators distinguish between jurisdictional and non-jurisdictional isolated wetlands. I propose that the merger of simple, source-sink-transport vector concepts with landscape-level assessment methods could be useful in this regard. I point to the need for documented examples of organisms that spend most of their lives in waters of the U.S. but also require isolated wetlands. I conclude that wetland science would benefit from the development of a comprehensive view of isolation as a formative process across different regional wetland types.

Zebrafish: as an integrative model for twenty-first century toxicity testing.

Abstract: The zebrafish embryo is a useful small model for investigating vertebrate development because of its transparency, low cost, transgenic and morpholino capabilities, conservation of cell signaling, and concordance with mammalian developmental phenotypes. From these advantages, the zebrafish embryo has been considered as an alternative model for traditional in vivo developmental toxicity screening. The use of this organism in conjunction with traditional in vivo developmental toxicity testing has the potential to reduce cost and increase throughput of testing the chemical universe, prioritize chemicals for targeted toxicity testing, generate predictive models of developmental toxicants, and elucidate mechanisms and adverse outcome pathways for abnormal development. This review gives an overview of the zebrafish embryo for pre dictive toxicology and 21st century toxicity testing. Developmental eye defects were selected as an example to evaluate data from the U.S. Environmental Protection Agency's ToxCast program comparing responses in zebrafish embryos with those from pregnant rats and rabbits for a subset of 24 environmental chemicals across >600 in vitro assay targets. Cross-species comparisons implied a common basis for biological pathways associated with neuronal defects, extracellular matrix remodeling, and mitotic arrest.

Exposure to Perfluorinated Alkyl Substances and Health Outcomes in Children: A Systematic Review of the Epidemiologic Literature.

Abstract: Perfluoroalkyl substances (PFAS), chemicals used to make products stain and stick resistant, have been linked to health effects in adults and adverse birth outcomes. A growing body of literature also addresses health effects in children exposed to PFAS. This review summarizes the epidemiologic evidence for relationships between prenatal and/or childhood exposure to PFAS and health outcomes in children as well as to provide a risk of bias analysis of the literature. A systematic review was performed by searching PubMed for studies on PFAS and child health outcomes. We identified 64 studies for inclusion and performed risk of bias analysis on those studies. We determined that risk of bias across studies was low to moderate. Six categories of health outcomes emerged. These were: immunity/infection/asthma, cardio-metabolic, neurodevelopmental/attention, thyroid, renal, and puberty onset. While there are a limited number of studies for any one particular health outcome, there is evidence for positive associations between PFAS and dyslipidemia, immunity (including vaccine response and asthma), renal function, and age at menarche. One finding of note is that while PFASs are mixtures of multiple compounds few studies examine them as such, therefore the role of these compounds as complex mixtures remains largely unknown.