Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Environmental Protection Agency”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,657 records · Page 92Linked to original sources
PubMed1995

The application of dosimetry models to identify key processes and parameters for default dose-response assessment approaches.

Mathematical dosimetry models should improve the accuracy of various extrapolations required in dose-response assessment because they include explicit descriptions of the major mechanistic determinants of the exposure-dose-response continuum. The availability of these anatomic and physiologic parameters for different mammalian species (including humans) and the physicochemical parameters for individual chemicals is an important consideration in the formulation of model structures and the application of simplifying assumptions to develop default models. A framework is presented that includes iterative development of model structures as more data become available. Development of the default dosimetry adjustments for interspecies extrapolation used in the inhalation reference concentration (RfC) methods of the U.S. Environmental Protection Agency (EPA) is discussed as an example of iterative model development, a process intended to ensure that model structures are commensurate with available data. The framework also aids evaluation of different model structures and can be applied to identify key parameters. Examples are provided to illustrate how insight on the key mechanistic determinants of exposure-dose-response can guide interpretation of data in the absence of comprehensive model structures, identify gaps in the database for a given chemical, or direct data gathering for chemicals that are yet to enter production.

Animals↗
PubMed1995

Understanding mechanisms of inhaled toxicants: implications for replacing default factors with chemical-specific data.

Assessing risk of inhaled materials is a challenging endeavor because of the profound interspecies differences in respiratory tract anatomy, physiology, and biochemistry. Recent advances in the availability of mechanistic data and mathematical models for describing dosimetry behavior of particles and gases has lead to improvements in default approaches to risk assessment of inhaled materials. An overview of some of the more well-understood differences between species in factors controlling dosimetry and response, and the default approach of the U.S. Environmental Protection Agency that accounts for many of these factors, are presented. The default methodology also creates a framework which inhalation toxicologists can use to direct research at reducing uncertainty in risk assessments that might otherwise be handled through default uncertainty factors. The optimal approach to risk assessment is to develop chemical-specific mode of action and dosimetry data that can be used quantitatively to replace the entire default approach. The toxicology of vinyl acetate and recent efforts to develop data to supplant assumptions made in the default approach are presented. The conclusion is drawn that the future of inhalation toxicity risk assessment lies in reducing uncertainties associated with interspecies extrapolation and that to do this effectively requires approaches to toxicology that are outside of routine testing paradigms, and are aimed at elucidating mechanisms of action through hypothesis-driven research.

Administration, Inhalation↗
PubMedDate not supplied

Uses of the coefficient of detection and sample size determination.

The coefficient of detection (CD) is said to represent the minimal difference statistically detectable with a t-test at some preselected alpha. Although the CD does not explicitly take statistical power into consideration, it is mathematically and empirically demonstrable that the CD operates at approximately 50% power. The CD, as reported in the Collaborative Behavioral Teratology Study (CBTS), also applies only to hypotheses about the difference between one sample mean and a selected standard value, and, consequently, does not apply to a situation where a difference between two sample means is considered. Therefore, the low one-sample CDs reported in the CBTS cannot be used to approximate sample sizes for purposes of meeting the requirement by the Environmental Protection Agency that a 20% difference between two sample means (e.g., control vs. experimental groups) should be detected with a power of 80% (or 90%) at a 5% certainty level.

Animals↗
PubMedDate not supplied

Scientific and regulatory issues relevant to assessing risk for developmental neurotoxicity: an overview.

The effects of chemical exposure on the developing nervous system have been documented in both humans and animals for a variety of agents. However, the comparability of these effects has not been carefully evaluated to determine the predictability of animal models to adverse effects in humans. A workshop sponsored by the U.S. Environmental Protection Agency (EPA) and the National Institute on Drug Abuse was held on April 11-13, 1989, to address the Qualitative and Quantitative Comparability of Human and Animal Developmental Neurotoxicity. Invited experts were asked to review the human and animal data on several agents that are known to cause developmental neurotoxicity in humans, including lead, methylmercury, selected abused agents, anticonvulsants, polychlorinated biphenyls (PCBs), ethanol and X-irradiation, and to make quantitative comparisons on a specific end point basis as well as on a functional category basis. In addition, they were asked to make quantitative comparisons when adequate dose-effect data were available. The data also were evaluated in the context of the proposed EPA developmental neurotoxicity testing battery to determine whether or not the battery would adequately detect the effects of each agent. Finally, four work groups were asked to reach consensus on issues relating to: 1) comparability of end points across species for developmental neurotoxicity; 2) testing methods in developmental neurotoxicity for use in human risk assessment; 3) weight-of-evidence and quantitative evaluation of data from developmental neurotoxicity studies; and 4) triggers for developmental neurotoxicity testing.

Animals↗
PubMedDate not supplied

Study design considerations in developmental neurotoxicology.

It is widely accepted that exposure to environmental factors during development can result in effects other than death, gross structural abnormality, or altered growth. One area of concern is the developing nervous system, which may be especially vulnerable to environmental perturbation. Testing chemicals for potential developmental neurotoxicity has received a high priority and testing guidelines have been published and recently revised by the U.S. Environmental Protection Agency. These guidelines are based on several principles of developmental neurotoxicity that have been developed during several years of research. In general, manifestation of neurotoxicity following developmental exposure can depend on the time at which exposure occurs and for the purposes of hazard detection, experiments should be designed to optimize the detection of neurotoxicity. In addition, maternal health and interaction with the offspring, as well as postnatal development are important design issues in developmental neurotoxicology. It is also widely accepted that several doses be used and multiple measures of neurotoxicity assessed in both genders at several points during the life span of the animal. Finally, the litter is usually regarded as the most appropriate statistical unit to control for genetic and maternal factors.

Animals↗
PubMed2005

Noise in the ED.

BACKGROUND: The impact of noise pollution on both the patient and the care provider has been extensively studied in the neonatal intensive care unit and in other critical care units. Noise pollution makes errors more probable and is one of the risk factors for provider burnout and negative outcomes for patients. The Environmental Protection Agency (EPA) recommends that the acceptable noise level in a hospital should not exceed 40 dB. OBJECTIVES: The purpose of this study was to record and analyze noise in a large urban level I emergency department (ED) and compare to the EPA guidelines. METHODS: A 3-channel dosimeter Quest Q300 (Quest Technologies, Oconomowoc, WI) was placed as a stand-alone unit on the wall of the resuscitation booth in the ED. Sound was sampled 16 times per second for 12 hours and was recorded as peaks and averages for each minute. The dosimeter was then placed in the pocket of a medical student with a small 8-mm shoulder-mount type 2 microphone. The medical student followed an emergency medicine resident throughout an 8-hour shift in the main resuscitation area while monitoring and logging sound fluctuations in the environment. Sound pressure levels were logged in real time and subsequently correlated to the recorded peaks. Sound was sampled 16 times per second and recorded peaks and averages for each minute. RESULTS: In the initial part of the study, the time-weighted average was 43 dB. The average sound levels peaked approximately 25 times over 12 hours. Individually measured peak levels of 94 to 117 dB occurred every minute. In the second part of the study, the time-weighted average was 52.9 dB. CONCLUSIONS: When compared to EPA accepted noise levels for hospital (40 dB), the ED under study had excessive noise on a regular basis. There are easily identifiable sources of noise pollution in the ED. By identifying and modifying sources of noise, stress in the ED may be decreased.

Emergency Service, Hospital↗
PubMed2006

Broad-spectrum microbicidal activity, toxicologic assessment, and materials compatibility of a new generation of accelerated hydrogen peroxide-based environmental surface disinfectant.

BACKGROUND: Concerns on human and environmental safety and label claims of many microbicides point to the need for safer, faster acting, and broad-spectrum substitutes. ACCEL TB, a 0.5% accelerated H(2)O(2) (AHP)-based disinfectant described here, is a potential candidate. METHODS: ACCEL TB was tested for its broad-spectrum microbicidal activity, safety and materials compatibility using internationally accepted protocols. Activity against bacteria (Staphylococcus aureus, Escherichia coli, Acinetobacter baumannii, Pseudomonas aeruginosa, vancomycin-resistant Enterococcus faecalis, methicillin-resistant Staphylococcus aureus, and Salmonella choleraesuis) was tested with the AOAC use-dilution method and the first tier of a quantitative carrier test (QCT-1). Mycobactericidal activity was tested against Mycobacterium bovis and Mycobacterium terrae using a quantitative suspension test (QST) and QCT-1, respectively. Fungicidal activity (Trichophyton mentagrophytes) was determined with the AOAC test and QCT-1. Activity against several enveloped and nonenveloped viruses was evaluated using the American Society for Testing and Materials (ASTM) method No. E-1053. Sanitizing action was tested against 7 types of vegetative bacteria with method No. DIS/TSS-10. All microbicidal tests contained an added soil load; in all AOAC tests, it was 5% fetal bovine serum, and, in QCT-1, a mixture of 3 types of proteins in phosphate buffer was used instead. The methods to test for acute oral, dermal, inhalation toxicities, and dermal and eye irritation as well as skin sensitization complied with the requirements of the Organization for Economic Cooperation and Development and the US Environmental Protection Agency (OPPTS 870). Standard methods were also used to test compatibility with metals and plastics. RESULTS: At 20 degrees C, the full-strength product was bactericidal and virucidal in 1 minute and mycobactericidal and fungicidal in 5 minutes. It was nonirritating to skin and eyes. The acute oral LD(50) (lethal dose 50%) was >5000 mg/kg. It was compatible with 12 types of plastic and 3 out of 4 metals. CONCLUSION: The tested formulation showed a high safety and materials compatibility profile in addition to being a fast acting, intermediate-level disinfectant.

Animals↗
PubMed2006

Particulate air pollution and hospital admissions for congestive heart failure in seven United States cities.

The association between short-term elevations in ambient particulate air pollution and increased cardiovascular morbidity and mortality is well documented. Ambient particles may also trigger acute decompensation in patients with congestive heart failure (CHF), but this hypothesis has not been evaluated in a systematic manner. This study evaluated the association between daily levels of respirable particulate matter of aerodynamic diameters < or =10 microm (PM10) and the rate of hospitalization from the emergency room for CHF in Medicare recipients (age > or = 65 years) in 7 United States cities from 1986 and 1999. The time-stratified case-crossover design was used to separately estimate the effect of a 10 microg/m3 increase in PM10 in each city. A combined random-effects estimate was then obtained from the city-specific effect estimates. There were 292,918 admissions with primary diagnoses of CHF during the observation period. Overall, a 10 microg/m3 increase in PM10 was associated with a 0.72% (95% confidence interval 0.35% to 1.10%) increase in the rate of admission for CHF on the same day. The effect of PM10 appeared to be less in patients with secondary diagnoses of hypertension. There was no consistent effect modification by age, gender, race, or any other secondary diagnosis evaluated. In conclusion, these results support the hypothesis that elevated levels of particulate air pollution, below the current limits set by the United States Environmental Protection Agency, are associated with an increase in the rate of hospital admission for exacerbation of CHF.

Aged↗
PubMed2006

Comparative study of four extraction methods for enterovirus recovery from wastewater and sewage sludge.

This study investigated four methods for the recovery of enteroviruses from sterilized raw wastewater, activated sludge, thickened sludge and treated wastewater, inoculated with Echovirus 11, Gregory prototype. The adsorption-elution method recommended by the US Environmental Protection Agency (EPA) was better for Echovirus 11 recovery than a sonication method, a modified EPA method and a membrane adsorption elution method since it resulted in the highest detection levels by cell culture and RT-PCR (Friedman's test, p<0.00041 and p=0.041, respectively).

Cells, Cultured↗
PubMed2003

Sustainability of insect resistance management strategies for transgenic Bt corn.

Increasing interest in the responsible management of technology in the industrial and agricultural sectors of the economy has been met thorough the development of broadly applicable tools to assess the "sustainability" of new technologies. An arena ripe for application of such analysis is the deployment of transgenic crops. The new transgenic pesticidal or plant-incorporated protectant (PIP) crops have seen widespread application in the United States based on the features of higher yield, lower applications of insecticides, and control of mycotoxin content. However, open rejection of these new crops in Europe and in other countries has been a surprising message and has limited their worldwide acceptance. The US Environmental Protection Agency's (USEPA) Office of Pesticide Programs (OPP) has worked on the development and analysis of insect resistance management (IRM) strategies and has mandated specific IRM requirements for Bacillus thuringiensis (Bt) crops since 1995 under the Food, Fungicide, Insecticide, and Rodenticide Act. Improvement of data quality and sustainability of IRM strategies have been targeted in an ongoing partnership between the USEPA Office of Research and Development and the Office of Pesticide Programs that will further enhance the agency's ability to develop sustainable insect resistance management strategies for transgenic field corn (Bt corn) producing B. thuringiensis (Bt) insecticidal proteins.

Animals↗
PubMed2006

Formation of depurinating N3adenine and N7guanine adducts after reaction of 1,2-naphthoquinone or enzyme-activated 1,2-dihydroxynaphthalene with DNA. Implications for the mechanism of tumor initiation by naphthalene.

Naphthalene is considered by the US Environmental Protection Agency to be a carcinogenic compound based on inhalation studies in rats. The primary metabolite of naphthalene is naphthalene 1,2-arene oxide. This unstable intermediate can lead to formation of 1-naphthol and naphthalene-1,2-dihydrodiol. Secondary metabolites include 1,2-dihydroxynaphthalene (1,2-DHN), which can be further oxidized to 1,2-naphthoquinone (1,2-NQ). Based on the metabolism of naphthalene and its similarity to the metabolic activation of carcinogenic natural estrogens, synthetic estrogens and benzene, we hypothesize that naphthalene is activated to initiate cancer by reaction of 1,2-NQ with DNA to form the depurinating adducts 1,2-DHN-4-N3Ade and 1,2-DHN-4-N7Gua. These adducts were synthesized by reaction of 1,2-NQ with Ade or dG in acetic acid/water/DMF (1:1:1). 1,2-NQ was reacted with DNA, and the depurinating 1,2-DHN-4-N3Ade and 1,2-DHN-4-N7Gua adducts were analyzed by ultraperformance liquid chromatography/tandem mass spectrometry and HPLC with electrochemical detection. After the reaction of 1,2-NQ with DNA, the N3Ade and N7Gua adducts were found. Similarly, when 1,2-DHN was activated by tyrosinase in the presence of DNA, higher amounts of the N3Ade and N7Gua adducts were detected. These same adducts were also formed when 1,2-DHN was activated by prostaglandin H synthase or 3-methylcholanthrene-induced rat liver microsomes in the presence of DNA. These depurinating adducts are analogous to those obtained from the ortho-quinones of natural estrogens, synthetic estrogens and benzene. These results suggest that reaction of ortho-quinones with DNA by 1,4-Michael addition is a general mechanism of weak carcinogenesis that occurs with naphthalene and a number of other aromatic compounds.

Adenine↗
PubMed2005

Assessment of the mechanical stability and chemical leachability of immobilized electroplating waste.

The effectiveness of cement based treatment technology, in immobilizing chromium laden electroplating sludge was assessed by conducting toxicity characteristic leaching procedure (TCLP). The mechanical stability of the blocks was tested by measuring the compressive strength. Other leaching tests such as NEN 7341 test, ANS 16.1 and multiple TCLP (MTCLP) test conducted on select solidified blocks showed that chromium was immobilized by the binder studied. A linear relationship was obtained between the cumulative fraction of chromium leached (CFL) and square root of time in the solidified samples proving that diffusion is the controlling mechanism for leaching of chromium. The leachability indices (LI) obtained for the solidified materials using cement and cement-fly ash system (EPC6, EPFC6A and EPFC6B) satisfy the guidance value as per US NRC, which clearly indicates that chromium is well retained within the solid matrix. Chromium concentrations in the TCLP leachates of the above mix ratios were well within the regulatory level of United States Environmental Protection Agency (USEPA). Molecular characterization of the solidified material was carried out using Fourier transformation infra red (FTIR) technique.

Chromium↗
PubMed2005

Estimation of the volatilization of organic compounds from soil surfaces.

Several simple models for the estimation of the half-life (t(1/2)) for the depletion of an organic chemical from a soil surface to air were examined. For moist surfaces, two models are proposed: the first requires knowledge of the soil/organic carbon partition coefficient (K(oc)) and the Henry's law constant (H) and the second the vapor pressure (P(s)) of the chemical involved. Due to uncertainties in the experimental K(oc) values those ones predicted by the group-contribution model of Meylan et al. [Environ. Sci. Technol. 26 (1992) 1560]-and proposed by the U.S. Environmental Protection Agency (EPA)-should be used. If reliable experimental P(s) values are not available, the first model is proposed, where in cases when H values are not available, predicted ones by the Bond-Contribution method of Meylan and Howard [Environ. Toxicol. Chem. 10 (1991) 1283]-and also proposed by EPA-can be used. In general, the agreement of the predicted t(1/2) values with the measured ones is within a factor of 3-5. Similar expressions, but with somewhat poorer results, are presented for dry field soils. In all cases, the obtained results represent a substantial improvement over those obtained with the currently used Dow method: t(1/2) = 1.58 x 10(-8)((K(oc) x S)/P(S)), where S is the solubility of the compound in water.

Half-Life↗
PubMed2006

Occurrence of sulfonamide antimicrobials in private water wells in Washington County, Idaho, USA.

Samples from six private wells formerly used as sources for drinking water by the residents of Washington County (Weiser, Idaho) were collected to assess the impact of a nearby confined animal feeding operation (CAFO) on the quality of the local groundwater. All six samples were found contaminated by two veterinary antimicrobials, sulfamethazine (at concentrations from 0.076 to 0.22 microg/l) and sulfadimethoxine (at concentrations from 0.046 to 0.068 microg/l). These groundwater samples also contained elevated concentrations of nitrate and ammonium. Three of the sampled wells have nitrate levels that exceeded the maximum contaminant level set by the US Environmental Protection Agency for drinking water, with nitrate concentration as high as 39.1mg/l. All but one well showed nitrate, which instead contained ammonium at 1.22 mg/l. Analysis of the nitrate and ammonium in these samples by isotopic ratio mass spectrometry indicated delta(15)N characteristic of an animal or human waste source. Results from this study underscore the role of CAFO as an important source of antibiotic contamination of groundwater.

Anti-Infective Agents↗
PubMed2006

Persistent organic pollutants (POPs) in the conventional activated sludge treatment process: model predictions against experimental values.

The FATE and treatibility estimator (FATE) model, developed by the United States Environmental Protection Agency was used for the prediction of the FATE of 26 persistent organic pollutants (POPs), i.e. 7 PCBs and 19 organochlorine compounds (OCs), during the conventional activated sludge treatment process applied in the waste water treatment plant (WWTP) of Thessaloniki, Greece. The removal rates predicted by the model for the primary and the secondary treatment stages were found to differ substantially from those experimentally measured. When the overall treatment was considered, the differences between measured and model predicted removals were within acceptable limits of confidence. Possible reasons that might cause deviations from experimental values were suggested to be the wastewater content in dissolved organic carbon (DOC), and/or the low concentrations of POPs in untreated wastewater.

Adsorption↗
PubMed2006

Estimation of acceptable mercury intake from fish in Taiwan.

The US Food and Drug Administration (USFDA) and Environmental Protection Agency (USEPA) are advising women and young children to avoid eating fish that contain high levels of mercury (Hg). However in Taiwan, the annual Black Fin Tuna Festival encourages the public to consume fish. The aim of this study was to assess fish intake in relation to the health risks of mercury exposure and calculate the acceptable and safe intake of fish in children and women of childbearing age. From the Monte Carlo simulation, based on USEPA's reference dose (0.1 microgkg(-1)d(-1)), we found that 21.6%-24.3% and 45.6%-57.4% of the daily mercury dose estimates exceeded the reference dose for typical and high-seafood consumers. The acceptable ingestion rates are <50 g d(-1) (children) and 90.8 +/- 15.7 g d(-1) (women of childbearing). Sensitivity analysis suggests that Hg concentration in fish may be a key parameter to aid governments as they offer guidance for risk management.

Adult↗
PubMed2004

New materials for solid-phase extraction and multiclass high-performance liquid chromatographic analysis of pesticides in grapes.

Sample preparation procedures which included the use of new aminopropyl (NH2) and octadecyl (C18) solid-phase extraction (SPE) sorbents are proposed for the simultaneous multiclass determination of the fungicide benomyl and of the herbicides tebuthiuron, diuron, simazine, atrazine, and ametryn in grapes, using single wavelength high-performance liquid chromatography. Sorbent preparation uses a fast, easy, and effective procedure to obtain silica-based materials, made by depositing polysiloxanes on a silica support followed by thermal immobilization. Recovery results of the compounds, after elution from the SPE cartridges, indicate that the most efficient system employed silica loaded with 40% of an aminofunctional polydimethylsiloxane as sorbent, using dichloromethane:methanol (95:5, v/v) as eluent. Method validation, carried out in agreement with International Conference on Harmonization directives, was performed at three fortification levels (100, 200, and 1000 microg kg(-1)). Limits of detection and quantification show that the method developed can be used to detect the pesticides at concentrations below the maximum residue levels established by Codex Alimentarius, the US Environmental Protection Agency, the European Union, and Brazilian legislation.

Chromatography, High Pressure Liquid↗
PubMed2004

New suppressor technology improves the ion chromatographic determination of inorganic anions and disinfection by-products in drinking water.

This paper describes a new suppressor technology for analyzing water samples using United States Environmental Protection Agency (EPA) methods 300.0 and 300.1. The Alltech DS-Plus suppressor improves and simplifies anion analysis in drinking water. In addition to suppressing the carbonate mobile phase and enhancing the analyte signal like conventional ion chromatography (IC) suppressors, the DS-Plus suppressor removes carbonic acid (as dissolved carbon dioxide) from the suppressor effluent before detection (US patent Nos.: 6444475; 6468804; others pending), lowering the background conductivity to near zero. Anions are detected in water background, improving sensitivity and lowering detection limits. The water-dip often seen with conventional suppressors is greatly reduced, improving fluoride quantification. The DS-Plus suppressor operates continuously without the need for external regenerants or switching valves. The performance of this new suppressor for analyzing water samples has been found to meet the EPA methods specifications.

Anions↗