Showing papers by "United States Environmental Protection Agency published in 1995"
TL;DR: It is reported that the major and persistent DDT metabolite,P,P′-DDE (l,l-dichloro-2,2-bis(P- chlorophenyl)ethylene), has little ability to bind the oestrogen receptor, but inhibits androgen binding to the androgen receptor.
Abstract: The increase in the number of reports of abnormalities in male sex development in wildlife and humans coincided with the introduction of 'oestrogenic' chemicals such as DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) into the environment. Although these phenotypic alterations are thought to be mediated by the oestrogen receptor, they are also consistent with inhibition of androgen receptor-mediated events. Here we report that the major and persistent DDT metabolite, p,p'-DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene), has little ability to bind the oestrogen receptor, but inhibits androgen binding to the androgen receptor, androgen-induced transcriptional activity, and androgen action in developing, pubertal and adult male rats. The results suggest that abnormalities in male sex development induced by p,p'-DDE and related environmental chemicals may be mediated at the level of the androgen receptor.
1,513 citations
TL;DR: In this paper, a multivariate factor analysis was used to identify the common axes (or dimensions) of pattern and structure which were measured by a reduced set of 26 metrics, which were interpreted as composite measures of average patch compaction, overall image texture, average patch shape, patch perimeter-area scaling, number of attribute classes, and large-patch density area scaling.
Abstract: Fifty-five metrics of landscape pattern and structure were calculated for 85 maps of land use and land cover. A multivariate factor analysis was used to identify the common axes (or dimensions) of pattern and structure which were measured by a reduced set of 26 metrics. The first six factors explained about 87% of the variation in the 26 landscape metrics. These factors were interpreted as composite measures of average patch compaction, overall image texture, average patch shape, patch perimeter-area scaling, number of attribute classes, and large-patch density-area scaling. We suggest that these factors can be represented in a simpler way by six univariate metrics - average perimeter-area ratio, contagion, standardized patch shape, patch perimeter-area scaling, number of attribute classes, and large-patch density-area scaling.
1,217 citations
TL;DR: In healthy adults with no serologic evidence of past infection with C. parvum, a low dose of C.Parvum oocysts is sufficient to cause infection, and there were no secondary cases of diarrhea among household contacts.
Abstract: Background Small numbers of Cryptosporidium parvum oocysts can contaminate even treated drinking water, and ingestion of oocysts can cause diarrheal disease in normal as well as immunocompromised hosts. Since the number of organisms necessary to cause infection in humans is unknown, we performed a study to determine the infective dose of the parasite in healthy adults. Methods After providing informed consent, 29 healthy volunteers without evidence of previous C. parvum infection, as determined by the absence of anti-cryptosporidium–specific antibodies, were given a single dose of 30 to 1 million C. parvum oocysts obtained from a calf. They were then monitored for oocyst excretion and clinical illness for eight weeks. Household contacts were monitored for secondary spread. Results Of the 16 subjects who received an intended dose of 300 or more oocysts, 14 (88 percent) became infected. After a dose of 30 oocysts, one of five subjects (20 percent) became infected, whereas at a dose of 1000 or more oocysts, ...
884 citations
TL;DR: In this paper, the authors assemble and analyze quantitative annual input-export budgets for total nitrogen (TN) and total phosphorus (TP) for Chesapeake Bay and three of its tributary estuaries (Potomac, Patuxent, and Choptank rivers).
Abstract: In this paper we assemble and analyze quantitative annual input-export budgets for total nitrogen (TN) and total phosphorus (TP) for Chesapeake Bay and three of its tributary estuaries (Potomac, Patuxent, and Choptank rivers). The budgets include estimates of TN and TP sources (point, diffuse, and atmospheric), internal losses (burial in sediments, fisheries yields, and denitrification), storages in the water column and sediments, internal cycling rates (zooplankton excretion and net sediment-water flux), and net downstream exchange. Annual terrestrial and atmospheric inputs (average of 1985 and 1986 data) of TN and TP ranged from 4.3 g TN m−2 yr−1 to 29.3 g TN m−2 yr−1 and 0.32 g TP m−2 yr−1 to 2.42 g TP m−2 yr−1, respectively. These rates of TN and TP input represent 6-fold to 8-fold and 13-fold to 24-fold increases in loads to these systems since the precolonial period. A recent 11-yr record for the Susquehanna River indicates that annual loads of TN and TP have varied by about 2-fold and 4-fold, respectively. TN inputs increased and TP inputs decreased during the 11-yr period. The relative importance of nutrient sources varied among these estuaries: point sources of nutrients delivered about half the annual TN and TP load to the Patuxent and nearly 60% of TP inputs to the Choptank; diffuse sources contributed 60–70% of the TN and TP inputs to the mainstream Chesapeake and Potomac River. The direct deposition of atmospheric wet-fall to the surface waters of these estuaries represented 12% or less of annual TN and TP loads except in the Choptank River (37% of TN and 20% of TP). We found direct, although damped, relationships between annual rates of nutrient input, water-column and sediment nutrient stocks, and nutrient losses via burial in sediments and denitrification. Our budgets indicate that the annual mass balance of TN and TP is maintained by a net landward exchange of TP and, with one exception (Choptank River), a net seaward transport of TN. The budgets for all systems revealed that inorganic nutrients entering these estuaries from terrestrial and atmospheric sources are rapidly converted to particulate and organic forms. Discrepancies between our budgets and others in the literature were resolved by the inclusion of sediments derived from shoreline erosion. The greatest potential for errors in our budgets can be attributed to the absence of or uncertainties in estimates of atmospheric dry-fall, contributions of nutrients via groundwater, and the sedimentation rates used to calculate nutrient burial rates.
602 citations
TL;DR: An overview of the principals of the electrokinetic remediation technique in soils is presented in this paper, where the types of waste and media in which the technology could potentially be applicable are outlined and some envisioned environmental uses of conduction phenomena in soils under electric fields.
565 citations
18 Jun 1995
TL;DR: A variable speed wind generation system where fuzzy logic principles are used for efficiency optimization and performance enhancement control and the complete control system has been developed, analyzed, and validated by simulation study.
Abstract: The paper describes a variable speed wind generation system where fuzzy logic principles are used for efficiency optimization and performance enhancement control. A squirrel cage induction generator feeds the power to a double-sided pulse width modulated converter system which pumps power to a utility grid or can supply to an autonomous system. The generation system has fuzzy logic control with vector control in the inner loops. A fuzzy controller tracks the generator speed with the wind velocity to extract the maximum power. A second fuzzy controller programs the machine flux for light load efficiency improvement, and a third fuzzy controller gives robust speed control against wind gust and turbine oscillatory torque. The complete control system has been developed, analyzed, and validated by simulation study. Performances have then been evaluated in detail.
501 citations
TL;DR: In this paper, water collected from riverine, near coastal, and salt marsh sources in the Southeastern United States was evaluated for its ability to produce both carbon monoxide (CO) and dissolved inorganic carbon (DIC) by photochemical oxidation of natural dissolved organic carbon (DOC).
Abstract: Water collected from riverine, near coastal, and salt marsh sources in the Southeastern United States was evaluated for its ability to produce both carbon monoxide (CO) and dissolved inorganic carbon (DIC) by photochemical oxidation of natural dissolved organic carbon (DOC). Irradiation of whole water samples using simulated sunlight produced CO at rates similar to those measured previously. Production rates for DIC were more than an order of magnitude higher than those observed for CO. Based on observed DIC formation rates, photo-oxidation of DOC by sunlight should be considered a dominant removal mechanism of organic carbon from the ocean.
482 citations
Journal Article•
TL;DR: A brief numerical analysis of the model reveals that uncertainty can account for a large proportion of the costs of the morning commute.
Abstract: Existing models of the commuting time-of-day choice are extended in order to analyze the effect of uncertain travel times. Travel time includes a time-varying congestion component and a random element specified by a probability distribution. Results from the uniform and exponential probability distributions are compared and the optimal "head start" time that the commuter chooses to account for travel time variability, i.e., a safety margin that determines the probability of arriving late for work, is derived. The model includes a one-time lateness penalty for arriving late as well as the per minute penalties for early and late arrival that other investigators have included. It also generalizes earlier work by accounting for the time variation in the predictable component of congestion, which interacts with uncertainty in interesting ways. A brief numerical analysis of the model reveals that uncertainty can account for a large proportion of the costs of the morning commute.
390 citations
TL;DR: The results indicate that androgen antagonists can act as agonists, depending on ligand binding affinity, concentration, and the presence of competing natural ligands.
327 citations
TL;DR: Overall, regardless of the test species, if phytotoxicity data are to be more available and effective in the hazard assessment process, additional information concerning species sensitivity, and environmental relevance of the results will be needed.
313 citations
TL;DR: The relationship between daily mortality of elderly (65+ y) persons and air pollution in the metropolitan area of Sao Paulo, Brazil, for the period May 1990 to April 1991 was evaluated by time series regression, controlling for season, weather, and other factors.
Abstract: The relationship between daily mortality of elderly (65+ y) persons and air pollution in the metropolitan area of Sao Paulo, Brazil, for the period May 1990 to April 1991 was evaluated by time series regression, controlling for season, weather, and other factors. Mortality was associated with respirable particles (PM10), nitrogen oxides (NOx), sulfur dioxide (SO2), and carbon monoxide (CO). The association with PM10 was most statistically significant, robust, and independent of other air pollutants. An increase in PM10 equal to 100 micrograms/m3 was associated with an increase in overall mortality equal to approximately 13%. This association was consistent across various model specifications and estimation techniques. The dose-response relationship between mortality and respirable particulate pollution was almost linear, with no evidence of a "safe" threshold level. The results were similar to those observed in London and several U.S. cities. The results were also supportive of recent animal studies that have observed adverse health outcomes in experimental animals exposed to air pollution in Sao Paulo.
University of Wisconsin-Madison1, United States Environmental Protection Agency2, Michigan State University3, University of Maryland, College Park4, University of Nebraska–Lincoln5, Yale University6, University of California, Berkeley7, Georgia Institute of Technology8, Duke University9, Vanderbilt University10, Oak Ridge National Laboratory11
TL;DR: The Ecosystem Valuation Forum was organized as a dialogue because it has been clear from the outset that agreement even on the meaning of the term "ecosystem valuation" could not be taken for granted as discussed by the authors.
TL;DR: Data indicate that while some effects of Aroclor 1254 exposure are dissimilar to drug-induced hypothyroidism, effects on hormone levels and body weight are comparable and may reflect the effects of thyroid hormone disruption on the development of the cochlea.
Wageningen University and Research Centre1, Karolinska Institutet2, Utrecht University3, United States Environmental Protection Agency4, University of Groningen5, University of California, Davis6, Lund University7, Norwegian University of Life Sciences8, Wayne State University9, Erasmus University Rotterdam10, University of Amsterdam11, University of Wisconsin-Madison12, Wadsworth Center13, University of Düsseldorf14
TL;DR: The lowest observable adverse effect levels (LOAELs) for developmental neurobehavioral and reproduction endpoints, based on body burden of TCDD-toxic equivalents (TEQs) in animals, are within the range of current background human body burdens.
TL;DR: Using data from the studies generating quantitative information concerning heritability of genetic effects, an assessment of the heritable genetic risk presented by acrylamide is presented and estimates for inhalation or dermal exposures suggest higher risks for induced genetic disease in offspring from fathers exposed in occupational settings.
Abstract: An updated review of the genotoxicity studies with acrylamide is provided. Then, using data from the studies generating quantitative information concerning heritability of genetic effects, an assessment of the heritable genetic risk presented by acrylamide is presented. The review offers a discussion of the reactions and possible mechanisms of genotoxic action by acrylamide and its epoxide metabolite glycidamide. Several genetic risk approaches are discussed, including the parallelogram, direct (actually a modified direct), and doubling dose approaches. Using data from the specific-locus and heritable translocation assays, the modified direct and doubling dose approaches are utilized to quantitate genetic risk. Exposures of male parents to acrylamide via inhalation, ingestion, and dermal routes are also quantitated. With these approaches and measurements and their underlying assumptions concerning extrapolation factors (including germ cell stage specificity, DNA repair variability, locus specificity), number of human loci associated with dominant disease alleles, and spontaneous mutation rates, an assessment of heritable genetic risk for humans is calculated for the three exposure scenarios. The calculated estimates for offspring from fathers exposed to acrylamide via drinking water are up to three offspring potentially affected with induced genetic disease per 10(8) offspring. Estimates for inhalation or dermal exposures suggest higher risks for induced genetic disease in offspring from fathers exposed in occupational settings.
TL;DR: In this paper, the authors used simple computational algorithms based on fundamental chemical structure theory to estimate ionization pKas of organic molecules strictly from molecular structure, where molecular structures are broken at each essential single bond into functional units with intrinsic properties.
Abstract: Ionization pKas for a large set of molecules were calculated using reactivity models developed in the computer program SPARC. SPARC uses relatively simple computational algorithms based on fundamental chemical structure theory to estimate ionization pKas of organic molecules strictly from molecular structure. Molecular structures are broken at each essential single bond into functional units with intrinsic properties. Reaction centers (acid or base) are identified and the impact of appended molecular structure on ionization pKa is quantified by perturbation theory. Resonance, electrostatic, solvation and H-bonding models have been developed and tested on 4338 pKas for 3685 compounds. The RMS deviation for the acids and the amino reaction center was 0.36 pKa units whereas that for the in-ring N and = N reaction centers was 0.41. Microscopic ionization constants, zwitterionic constants, isoelectric points, and molecular speciation as a function of pH can be calculated using the SPARC models.
TL;DR: It is suggested that genetic manipulation or tissue culturing of the plants may have produced a change in plant characteristics, aside from B.t. kurstaki toxin production, that can influence growth and species composition of soil microorganisms.
TL;DR: It is shown that inflammatory cytokines are elevated in nasal secretions during acute URI in preschool children, and cytokine patterns in respiratory syncytial virus-positive and -negative illnesses did not differ significantly.
Abstract: Children in a day care center underwent serial nasal lavages in order to assess nasal cytokine expression during acute upper respiratory infections (URI). Interleukin (IL)-1 beta, IL-8, IL-6, and tumor necrosis factor-alpha (TNF-alpha) were markedly elevated in nasal lavage fluid during acute URI compared to baseline, and all except TNF-alpha decreased significantly by 2-4 weeks later. Cytokine patterns in respiratory syncytial virus-positive and -negative illnesses did not differ significantly. A subgroup of children also underwent superficial mucosal biopsy under the inferior nasal turbinate. During acute URI, biopsy cells (90%-95% epithelial) showed increased transcripts for IL-1 beta, IL-8, and IL-6 in 7 of 9 subjects, suggesting that epithelial cells may be one source of cytokines during acute URI. The results show that inflammatory cytokines are elevated in nasal secretions during acute URI in preschool children. Thus, cytokines are likely to participate in regulation of respiratory virus-induced inflammation.
TL;DR: In the LE rat, vaginal and behavioral estrous cyclicity, estrous cycle-mediated running wheel activity, and female sexual behaviors at proestrus were not affected by gestational GD 15 TCDD treatment, but untreated stud males had difficulty attaining intromission and took longer to ejaculate.
TL;DR: Challenges and possible opportunities for the development of biosensors for environmental monitoring applications are focused on.
TL;DR: The Fish and Temperature Database Matching System (FTDMS) as mentioned in this paper has been used to estimate thermal requirements for fishes, some proposed maximum temperature tolerances for several freshwater fish species, and how these FTDMS-derived values relate to various laboratory test results.
Abstract: In 1979, Biesinger et al. described a technique for spatial and temporal matching of records of stream temperatures and fish sampling events to obtain estimates of yearly temperature regimes for freshwater fishes of the United States. This article describes the state of this Fish and Temperature Database Matching System (FTDMS), its usage to estimate thermal requirements for fishes, some proposed maximum temperature tolerances for several freshwater fish species, and the way these FTDMS-derived values relate to various laboratory test results. Although applicable to all species for which collection records exist, initial development and refinement of FTDMS has focused on estimating the maximum weekly mean temperature tolerance for 30 common fishes of the United States. The method involves extensive use of automated data processing during data incorporation, quality assurance checks, data matching, and endpoint calculation. Maximum weekly mean temperatures derived from FTDMS were always less than ...
TL;DR: The up-and-down procedure (UDP), fixed-dose procedure (FDP) and conventional LD50 tests were compared to determine their consistency in chemical hazard classification for acute oral toxicity according to the European Economic Community (EEC) system.
TL;DR: The authors explored the use of 96-h acute toxicity tests with juvenile fathead minnows and primarily binary chemical mixtures to define the primary acute mode of toxic action for diverse industrial organic chemicals.
Abstract: An important aspect of understanding how multiple toxicants jointly act involves defining the primary mode of toxic action for the chemicals of interest. We have explored the use of 96-h acute toxicity tests with juvenile fathead minnows and primarily binary chemical mixtures to define the primary acute mode of toxic action for diverse industrial organic chemicals. Our investigation mainly considered the two special cases of noninteractive joint action known as concentration (simple similar) and response (independent) addition. The different forms of joint toxicity with binary mixtures were graphically illustrated by isoboie diagrams. Designated as the mode of action-specific reference toxicants were 1-octanol, phenol, and 2,4-dimtrophenol. It was observed from binary isobole diagrams that a chemical with a similar primary mode of toxic action to that of a reference toxicant would display a concentration-addition type of joint action with the reference toxicant over the entire mixture ratio range. Dissimilar chemicals with very steep concentration-response curves generally showed an interaction that was less-than-concentration additive, but consistently demonstrated a joint toxicity that was greater than predicted by the response-addition model. The more-than-concentration additive and complex isoboles that are indicative of interactive toxicity were not commonly observed in our experiments.
TL;DR: This is the first solid evidence for a negative relationship between plastic ingestion and physical condition in seabirds, and the likelihood that higher quality individuals are more prone to ingestplastic has serious implications regarding health of some seabird populations.
TL;DR: The integrated organic vapor/particle sampler (IOVPS) as discussed by the authors uses a cyclone inlet for removal of particles greater than 2.5 μm (D50) from the airstream, followed by two or three sandblasted glass annular denuders coated with ground particles of an adsorbent resin.
TL;DR: Because Bacteroides spp.
Abstract: Because Bacteroides spp. are obligate anaerobes that dominate the human fecal flora, and because some species may live only in the human intestine, these bacteria might be useful to distinguish human from nonhuman sources of fecal pollution. To test this hypothesis, PCR primers specific for 16S rRNA gene sequences of Bacteroides distasonis, B. thetaiotaomicron, and B. vulgatus were designed. Hybridization with species-specific internal probes was used to detect the intended PCR products. Extracts from 66 known Bacteroides strains, representing 10 related species, were used to confirm the specificity of these PCR-hybridization assays. To test for specificity in feces, procedures were developed to prepare DNA of sufficient purity for PCR. Extracts of feces from 9 humans and 70 nonhumans (cats, dogs, cattle, hogs, horses, sheep, goats, and chickens) were each analyzed with and without an internal positive control to verify that PCR amplification was not inhibited by substances in the extract. In addition, serial dilutions from each extract that tested positive were assayed to estimate the relative abundance of target Bacteroides spp. in the sample. Depending on the primer-probe set used, either 78 or 67% of the human fecal extracts tested had high levels of target DNA. On the other hand, only 7 to 11% of the nonhuman extracts tested had similarly high levels of target DNA. An additional 12 to 20% of the nonhuman extracts had levels of target DNA that were 100- to 1,000-fold lower than those found in humans.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: In this article, the authors used a combination of equilibrium partitioning, WSAR, toxic unit, additivity, and concentration-response models to estimate the toxicity of PAH-contaminated sediments.
Abstract: The {Sigma}PAH model estimates the probability of toxicity of PAH-contaminated sediments using a combination of equilibrium partitioning, WSAR, toxic unit, additivity, and concentration-response models. The sediment concentration of organic carbon and 13 PAH (polynuclear aromatic hydrocarbon) compounds were measured. Interstitial water concentrations (PAH{sub iw}) of the 13 compounds were predicted by equilibrium partitioning. The 10-d LC50 of each compound in interstitial water (10-d LC50{sub iw}) was predicted by a QSAR regression of 10-d LC50{sub iw} (From spiked sediment tests) to K{sub ow}. Toxic unit concentrations of individual compounds (TU{sub i}) were predicted as PAH{sub iw}/10-d LC50{sub iw}. The total number of toxic units of the 13 compounds ({Sigma}TU{sub i}) was calculated assuming the additivity of toxic effects of PAHs. {Sigma}TU{sub i} was used to predict the probability of toxicity to marine and estuarine amphipods using a concentration-response model derived from spiked sediment toxicity tests. The {Sigma}PAH model was verified by comparing predicted and observed toxicity in field-collected sediment samples. There was 86.6% correspondence and no significant difference between predicted and observed toxicity at PAH-contaminated sites. Ecological-effect levels predicted by the {Sigma}PAH model correspond with several sediment-quality guidelines.
TL;DR: This paper highlights several key methodological issues that need to be addressed as part of ongoing efforts to strengthen the scientific foundation for informed decision-making regarding environmental justice.
Abstract: There currently is a scarcity of scientific information to guide public policy decisions about issues of «environmental justice»; broadly defined as the goal of achieving adequate protection from the harmful effects of environmental agents for everyone, regardless of age, culture, ethnicity, gender, race, or socioeconomic status. This paper highlights several key methodological issues that need to be addressed as part of ongoing efforts to strengthen the scientific foundation for informed decision-making regarding environmental justice. Specifically, careful thought must be given to the selection of appropriate (1) statistical tests, (2) geographic unit(s) of analysis, (3) exposure estimators, and (4) comparison (reference) populations
TL;DR: Examination of the pattern of AhR expression in the C57BL/6N mouse embryo from gestation days (GD) 10–16 suggests that this novel ligand‐activated transcriptional regulator may be important in normal embryonic development.
Abstract: The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor with a basic region/helix-loop-helix (bHLH) motif. AhR has been sequenced and the functional domains defined and there is information on the formation of complexes with other peptides and interactions with DNA, although these areas continue to be investigated. AhR mediates many biological effects such as developmental toxicity, including induction of cleft palate and hydronephrosis. This regulatory protein is expressed in embryonic liver and has been immunohistochemically localized in cells of human and mouse secondary palate. The expression of AhR in embryonic tissues and its ability to disrupt development suggests a significant role for this protein in development. The present study examines the pattern of AhR expression in the C57BL/6N mouse embryo from gestation days (GD) 10–16, using in situ hybridization and immunohistochemical analysis. AhR mRNA was localized with 35S-RNA antisense riboprobe (cAh1 probe, 1.8 Kb amino terminal DNA). AhR protein was localized with purified monoclonal antibody (RPT-9) raised against the N-terminal peptide sequence. AhR mRNA and protein were expressed in GD 10–13 neuroepithelium, and as development progressed the levels in brain decreased. GD 10–12 embryos also showed AhR in branchial arches, heart, somites, and liver. AhR protein and mRNA in heart were highest at GD 10–11 and decreased with age. In liver, AhR mRNA and protein levels increased and nuclear localization became more pronounced with gestational age. In GD 14–16 embryos levels in liver and adrenal were highest, but AhR was present in ectoderm, bone, and muscle. AhR expression was specific for both cell type, organ/tissue, and developmental stage, suggesting that this novel ligand-activated transcriptional regulator may be important in normal embryonic development. © 1995 wiley-Liss, Inc.1
TL;DR: In vivo and in vitro bioluminescence methods that have been utilized to elucidate properties of chemicals, toxic and mutagenic effects, and to estimate biomass are focused on.