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.

Relief of amplification inhibition in PCR with bovine serum albumin or T4 gene 32 protein

Abstract: The benefits of adding bovine serum albumin (BSA) or T4 gene 32 protein (gp32) to PCR were evaluated with reaction mixtures containing substances that inhibit amplification. Whereas 10- to 1,000-fold more FeCl3, hemin, fulvic acids, humic acids, tannic acids, or extracts from feces, freshwater, or marine water were accommodated in PCR when either 400 ng of BSA per microl or 150 ng of gp32 per microl was included in the reactions, neither BSA nor gp32 relieved interference significantly when minimum inhibitory levels of bile salts, bilirubin, EDTA, NaCl, sodium dodecyl sulfate, or Triton X-100 were present. Use of BSA and gp32 together offered no more relief of inhibition than either alone at its optimal level, and neither protein had any noticeable effect on amplification in the absence of inhibitors.

Escherichia coli: the best biological drinking water indicator for public health protection

Abstract: Public health protection requires an indicator of fecal pollution. It is not necessary to analyse drinking water for all pathogens. Escherichia coli is found in all mammal faeces at concentrations of 10 log 9(-1), but it does not multiply appreciably in the environment. In the 1890s, it was chosen as the biological indicator of water treatment safety. Because of method deficiencies, E. coli surrogates such as the 'fecal coliform' and total coliforms tests were developed and became part of drinking water regulations. With the advent of the Defined Substrate Technology in the late 1980s, it became possible to analyse drinking water directly for E. coli (and, simultaneously, total coliforms) inexpensively and simply. Accordingly, E. coli was re-inserted in the drinking water regulations. E. coli survives in drinking water for between 4 and 12 weeks, depending on environmental conditions (temperature, microflora, etc.). Bacteria and viruses are approximately equally oxidant-sensitive, but parasites are less so. Under the conditions in distribution systems, E. coli will be much more long-lived. Therefore, under most circumstances it is possible to design a monitoring program that permits public health protection at a modest cost. Drinking water regulations currently require infrequent monitoring which may not adequately detect intermittent contamination events; however, it is cost-effective to markedly increase testing with E. coli to better protect the public's health. Comparison with other practical candidate fecal indicators shows that E. coli is far superior overall.

The Mussel Watch

Abstract: The levels of four sets of pollutants (heavy-metals, artificial radionuclides, petroleum components, and halogenated hydrocarbons), have been measured in U.S. coastal waters, using bivalves as sentinel organisms. The strategies of carrying out this programme are outlined and the results from the first year's work are given. Varying degrees of pollution in U.S. coastal waters have been indicated by elevated levels of pollutants in the bivalves, which comprised certain species of mussels and oysters and were collected at over one hundred localities.

Best practices for use of stable isotope mixing models in food-web studies

Abstract: Stable isotope mixing models are increasingly used to quantify consumer diets, but may be misused and misinter- preted. We address major challenges to their effective application. Mixing models have increased rapidly in sophistication. Current models estimate probability distributions of source contributions, have user-friendly interfaces, and incorporate com- plexities such as variability in isotope signatures, discrimination factors, hierarchical variance structure, covariates, and con- centration dependence. For proper implementation of mixing models, we offer the following suggestions. First, mixing models can only be as good as the study and data. Studies should have clear questions, be informed by knowledge of the system, and have strong sampling designs to effectively characterize isotope variability of consumers and resources on proper spatio-temporal scales. Second, studies should use models appropriate for the question and recognize their assumptions and limitations. Decisions about source grouping or incorporation of concentration dependence can influence results. Third, studies should be careful about interpretation of model outputs. Mixing models generally estimate proportions of assimilated resources with substantial uncertainty distributions. Last, common sense, such as graphing data before analyzing, is essential to maximize usefulness of these tools. We hope these suggestions for effective implementation of stable isotope mixing models will aid continued development and application of this field.