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.

The genotoxicity of industrial wastes and effluents.

Abstract: A review of the literature published on the genotoxicity of industrial wastes and effluents using short-term genetic bioassays is presented in this document. The importance of this task arises from the ubiquity of genotoxic compounds in the environment and the need to identify the sources of contamination so that efforts aimed at control and minimization can be implemented. Of even greater significance is the immediate concern for the welfare of human health and the environment. Subheadings of this document include a description of the genetic bioassays that have been used to test industrial wastes, a compendium of methods commonly used to prepare crude waste samples for bioassay, and a review of the genetic toxicity of wastes and effluents. Wastes and effluents have been grouped according to industrial source. Major categories include chemical and allied products, pulp and paper manufacturing, defense and munitions, petroleum refining, primary metal industries, and miscellaneous industrial manufacturers. Within each industrial category, a synopsis of individual genetic toxicity studies is presented, followed by an interpretation of results on a comprehensive, industry-wide basis. In this evaluation, a discussion of the types and extent of genotoxic damage caused by a particular set of wastes is presented, and potential sources of genotoxic activity are identified. Concluding the document is a commentary, which discloses potential shortcomings in the way in which current legislation protects human heath and the environment from the release of genotoxic substances via industrial wastes and effluents. It also provides an assessment of the genotoxic burden that industrial wastes place on the environment.

Environmental antiandrogens: low doses of the fungicide vinclozolin alter sexual differentiation of the male rat

Abstract: In humans and rodents, exposure to antiandrogenic chemicals during sexual differentiation can produce malformations of the reproductive tract. Perinatal administration of 100 or 200 mg vinclozolin (V) kg-1 day-1 during sexual differentiation in rats induces female-like anogenital distance (AGD), retained nipples, cleft phallus with hypospadias, suprainguinal ectopic scrota/testes, a vaginal pouch, epididymal granulomas, and small to absent sex accessory glands in male offspring. Vinclozolin is metabolized to at least two active forms, M1 and M2, that display antiandrogenic activity by binding the androgen receptor (AR). Here, we present information on the reproductive effects of oral treatment with low dosage levels of V during sexual differentiation of the male rat. Vinclozolin was administered to the dam at 0, 3.125, 6.25, 12.5, 25, 50, or 100 mg kg-1 day-1 from gestational day 14 to postnatal day 3 (the period of fetal/neonatal testicular testosterone synthesis and sexual differentiation). At doses of 3.125 mg V kg-1 and above, AGD was significantly reduced in newborn male offspring and the incidence of areolas was increased. These effects were associated with permanent alterations in other androgen-dependent tissues. Ventral prostate weight in one year old male offspring was reduced in all treatment groups (significant at 6.25, 25, 50, and 100 mg kg-1 day-1), and permanent nipples were detected in males at 3.125 (1.4%), 6.25 (3.6%), 12.5 (3.9%), 25 (8.5%), 50 (91%), and 100 (100%) mg V kg-1 day-1. To date, permanent nipples have not been observed in a control male from any study in our laboratory. Vinclozolin treatment at 50 and 100 mg kg-1 day-1 induced reproductive tract malformations and reduced ejaculated sperm numbers and fertility. Even though all of the effects of V likely result from the same initial event (AR binding), the different endpoints displayed a wide variety of dose-response curves and ED50's. The dose-response data for several of the functional endpoints failed to display an obvious threshold. These data demonstrate that V produces subtle alterations in sexual differentiation of the external genitalia, ventral prostate, and nipple tissue in male rat offspring at dosage levels below the previously described no-observed-effect-level (NOEL). These effects occur at a dosage level an order of magnitude below that required to induce malformations and reduce fertility. Hence, multigenerational reproduction studies of antiandrogenic chemicals that were not conducted under the Environmental Protection Agency's new Harmonized Multigenerational Test Guidelines, which include endpoints sensitive to antiandrogens at low dosage levels, could yield a NOEL that is at least an order of magnitude too high.

Bt crop effects on functional guilds of non-target arthropods: a meta-analysis.

Abstract: Background Uncertainty persists over the environmental effects of genetically-engineered crops that produce the insecticidal Cry proteins of Bacillus thuringiensis (Bt). We performed meta-analyses on a modified public database to synthesize current knowledge about the effects of Bt cotton, maize and potato on the abundance and interactions of arthropod non-target functional guilds. Methodology/Principal Findings We compared the abundance of predators, parasitoids, omnivores, detritivores and herbivores under scenarios in which neither, only the non-Bt crops, or both Bt and non-Bt crops received insecticide treatments. Predators were less abundant in Bt cotton compared to unsprayed non-Bt controls. As expected, fewer specialist parasitoids of the target pest occurred in Bt maize fields compared to unsprayed non-Bt controls, but no significant reduction was detected for other parasitoids. Numbers of predators and herbivores were higher in Bt crops compared to sprayed non-Bt controls, and type of insecticide influenced the magnitude of the difference. Omnivores and detritivores were more abundant in insecticide-treated controls and for the latter guild this was associated with reductions of their predators in sprayed non-Bt maize. No differences in abundance were found when both Bt and non-Bt crops were sprayed. Predator-to-prey ratios were unchanged by either Bt crops or the use of insecticides; ratios were higher in Bt maize relative to the sprayed non-Bt control. Conclusions/Significance Overall, we find no uniform effects of Bt cotton, maize and potato on the functional guilds of non-target arthropods. Use of and type of insecticides influenced the magnitude and direction of effects; insecticde effects were much larger than those of Bt crops. These meta-analyses underscore the importance of using controls not only to isolate the effects of a Bt crop per se but also to reflect the replacement of existing agricultural practices. Results will provide researchers with information to design more robust experiments and will inform the decisions of diverse stakeholders regarding the safety of transgenic insecticidal crops.

Stream restoration strategies for reducing river nitrogen loads

Abstract: Despite decades of work on implementing best management practices to reduce the movement of excess nitrogen (N) to aquatic ecosystems, the amount of N in streams and rivers remains high in many watersheds. Stream restoration has become increasingly popular, yet efforts to quantify N-removal benefits are only just beginning. Natural resource managers are asking scientists to provide advice for reducing the downstream flux of N. Here, we propose a framework for prioritizing restoration sites that involves identifying where potential N loads are large due to sizeable sources and efficient delivery to streams, and when the majority of N is exported. Small streams (1st–3rd order) with considerable loads delivered during low to moderate flows offer the greatest opportunities for N removal. We suggest approaches that increase in-stream carbon availability, contact between the water and benthos, and connections between streams and adjacent terrestrial environments. Because of uncertainties concerning the magnitud...

Probing the enantioselectivity of chiral pesticides.

Abstract: Enantiomer-specific formulatins could decrease pesticide use and protect the environment from unintended effects.