Showing papers by "United States Environmental Protection Agency published in 2004"

The Mann-Kendall test modified by effective sample size to detect trend in serially correlated hydrological series

Abstract: The non-parametric Mann-Kendall (MK) statistical test has been popularly used to assess the significance of trend in hydrological time series The test requires sample data to be serially independent When sample data are serially correlated, the presence of serial correlation in time series will affect the ability of the test to correctly assess the significance of trend To eliminate the effect of serial correlation on the MK test, effective sample size (ESS) has been proposed to modify the MK statistic This study investigates the ability of ESS to eliminate the influence of serial correlation on the MK test by Monte Carlo simulation Simulation demonstrates that when no trend exists within time series, ESS can effectively limit the effect of serial correlation on the MK test When trend exists within time series, the existence of trend will contaminate the estimate of the magnitude of sample serial correlation, and ESS computed from the contaminated serial correlation cannot properly eliminate the effect of serial correlation on the MK test However, if ESS is computed from the sample serial correlation that is estimated from the detrended series, ESS can still effectively reduce the influence of serial correlation on the MK test

Application of Ecological Indicators

Abstract: ▪ Abstract Ecological indicators have widespread appeal to scientists, environmental managers, and the general public. Indicators have long been used to detect changes in nature, but the scientific maturation in indicator development primarily has occurred in the past 40 years. Currently, indicators are mainly used to assess the condition of the environment, as early-warning signals of ecological problems, and as barometers for trends in ecological resources. Use of ecological indicators requires clearly stated objectives; the recognition of spatial and tempor al scales; assessments of statistical variability, precision, and accuracy; linkages with specific stressors; and coupling with economic and social indicators. Legislatively mandated use of ecological indicators occurs in many countries worldwide and is included in international accords. As scientific advancements and innovation in the development and use of ecological indicators continue through applications of molecular biology, computer technolog...

Environmental Health Disparities: A Framework Integrating Psychosocial and Environmental Concepts

Abstract: Although it is often acknowledged that social and environmental factors interact to produce racial and ethnic environmental health disparities, it is still unclear how this occurs. Despite continued controversy, the environmental justice movement has provided some insight by suggesting that disadvantaged communities face greater likelihood of exposure to ambient hazards. The exposure‐ disease paradigm has long suggested that differential “vulnerability” may modify the effects of toxicants on biological systems. However, relatively little work has been done to specify whether racial and ethnic minorities may have greater vulnerability than do majority populations and, further, what these vulnerabilities may be. We suggest that psychosocial stress may be the vulnerability factor that links social conditions with environmental hazards. Psychosocial stress can lead to acute and chronic changes in the functioning of body systems (e.g., immune) and also lead directly to illness. In this article we present a multidisciplinary framework integrating these ideas. We also argue that residential segregation leads to differential experiences of community stress, exposure to pollutants, and access to community resources. When not counterbalanced by resources, stressors may lead to

Heavy Metal Content of Ayurvedic Herbal Medicine Products

Abstract: ContextLead, mercury, and arsenic intoxication have been associated with the use of Ayurvedic herbal medicine product (HMPs).ObjectivesTo determine the prevalence and concentration of heavy metals in Ayurvedic HMPs manufactured in South Asia and sold in Boston-area stores and to compare estimated daily metal ingestion with regulatory standards.Design and SettingSystematic search strategy to identify all stores 20 miles or less from Boston City Hall that sold Ayurvedic HMPs from South Asia by searching online Yellow Pages using the categories markets, supermarkets, and convenience stores, and business names containing the word India, Indian cities, and Indian words. An online national directory of Indian grocery stores, a South Asian community business directory, and a newspaper were also searched. We visited each store and purchased all unique Ayurvedic HMPs between April 25 and October 24, 2003.Main Outcome MeasuresConcentrations (μg/g) of lead, mercury, and arsenic in each HMP as measured by x-ray fluorescence spectroscopy. Estimates of daily metal ingestion for adults and children estimated using manufacturers’ dosage recommendations with comparisons to US Pharmacopeia and US Environmental Protection Agency regulatory standards.ResultsA total of 14 (20%) of 70 HMPs (95% confidence interval, 11%-31%) contained heavy metals: lead (n = 13; median concentration, 40 μg/g; range, 5-37 000), mercury (n = 6; median concentration, 20 225 μg/g; range, 28-104 000), and/or arsenic (n = 6; median concentration, 430 μg/g; range, 37-8130). If taken as recommended by the manufacturers, each of these 14 could result in heavy metal intakes above published regulatory standards.ConclusionsOne of 5 Ayurvedic HMPs produced in South Asia and available in Boston South Asian grocery stores contains potentially harmful levels of lead, mercury, and/or arsenic. Users of Ayurvedic medicine may be at risk for heavy metal toxicity, and testing of Ayurvedic HMPs for toxic heavy metals should be mandatory.

Development of a passive, in situ, integrative sampler for hydrophilic organic contaminants in aquatic environments.

Abstract: Increasingly it is being realized that a holistic hazard assessment of complex environmental contaminant mixtures requires data on the concentrations of hydrophilic organic contaminants including new generation pesticides, pharmaceuticals, personal care products, and many chemicals associated with household, industrial, and agricultural wastes. To address this issue, we developed a passive in situ sampling device (the polar organic chemical integrative sampler [POCIS]) that integratively concentrates trace levels of complex mixtures of hydrophilic environmental contaminants, enables the determination of their time-weighted average water concentrations, and provides a method of estimating the potential exposure of aquatic organisms to the complex mixture of waterborne contaminants. Using a prototype sampler, linear uptake of selected herbicides and pharmaceuticals with log K(ow)s < 4.0 was observed for up to 56 d. Estimation of the ambient water concentrations of chemicals of interest is achieved by using appropriate uptake models and determination of POCIS sampling rates for appropriate exposure conditions. Use of POCIS in field validation studies targeting the herbicide diuron in the United Kingdom resulted in the detection of the chemical at estimated concentrations of 190 to 600 ng/L. These values are in agreement with reported levels found in traditional grab samples taken concurrently.

Human prostate cancer risk factors.

Abstract: Prostate cancer has the highest prevalence of any nonskin cancer in the human body, with similar likelihood of neoplastic foci found within the prostates of men around the world regardless of diet, occupation, lifestyle, or other factors. Essentially all men with circulating androgens will develop microscopic prostate cancer if they live long enough. This review is a contemporary and comprehensive, literature-based analysis of the putative risk factors for human prostate cancer, and the results were presented at a multidisciplinary consensus conference held in Crystal City, Virginia, in the fall of 2002. The objectives were to evaluate known environmental factors and mechanisms of prostatic carcinogenesis and to identify existing data gaps and future research needs. The review is divided into four sections, including 1) epidemiology (endogenous factors [family history, hormones, race, aging and oxidative stress] and exogenous factors [diet, environmental agents, occupation and other factors, including lifestyle factors]); 2) animal and cell culture models for prediction of human risk (rodent models, transgenic models, mouse reconstitution models, severe combined immunodeficiency syndrome mouse models, canine models, xenograft models, and cell culture models); 3) biomarkers in prostate cancer, most of which have been tested only as predictive factors for patient outcome after treatment rather than as risk factors; and 4) genotoxic and nongenotoxic mechanisms of carcinogenesis. The authors conclude that most of the data regarding risk relies, of necessity, on epidemiologic studies, but animal and cell culture models offer promise in confirming some important findings. The current understanding of biomarkers of disease and risk factors is limited. An understanding of the risk factors for prostate cancer has practical importance for public health research and policy, genetic and nutritional education and chemoprevention, and prevention strategies.

Glyceraldehyde 3-phosphate dehydrogenase-s, a sperm-specific glycolytic enzyme, is required for sperm motility and male fertility

Abstract: Although glycolysis is highly conserved, it is remarkable that several unique isozymes in this central metabolic pathway are found in mammalian sperm. Glyceraldehyde 3-phosphate dehydrogenase-S (GAPDS) is the product of a mouse gene expressed only during spermatogenesis and, like its human ortholog (GAPD2), is the sole GAPDH isozyme in sperm. It is tightly bound to the fibrous sheath, a cytoskeletal structure that extends most of the length of the sperm flagellum. We disrupted Gapds expression by gene targeting to selectively block sperm glycolysis and assess its relative importance for in vivo sperm function. Gapds–/– males were infertile and had profound defects in sperm motility, exhibiting sluggish movement without forward progression. Although mitochondrial oxygen consumption was unchanged, sperm from Gapds–/– mice had ATP levels that were only 10.4% of those in sperm from WT mice. These results imply that most of the energy required for sperm motility is generated by glycolysis rather than oxidative phosphorylation. Furthermore, the critical role of glycolysis in sperm and its dependence on this sperm-specific enzyme suggest that GAPDS is a potential contraceptive target, and that mutations or environmental agents that disrupt its activity could lead to male infertility.

Halonitromethane drinking water disinfection byproducts: chemical characterization and mammalian cell cytotoxicity and genotoxicity.

Abstract: Halonitromethanes are drinking water disinfection byproducts that have recently received a high priority for health effects research from the U.S. Environmental Protection Agency (EPA). Our purpose was to identify and synthesize where necessary the mixed halonitromethanes and to determine the chronic cytotoxicity and the acute genotoxicity of these agents in mammalian cells. The halonitromethanes included bromonitromethane (BNM), dibromonitromethane (DBNM), tribromonitromethane (TBNM), bromochloronitromethane (BCNM), dibromochloronitromethane (DBCNM), bromodichloronitromethane (BDCNM), chloronitromethane (CNM), dichloronitromethane (DCNM), and trichloronitromethane (TCNM). Low- and high-resolution gas chromatography/mass spectrometry (GC/MS) was used to identify the mixed chloro-bromonitromethanes in finished drinking waters, and analytical standards that were not commercially available were synthesized (BDCNM, DBCNM, TBNM, CNM, DCNM, BCNM). The rank order of their chronic cytotoxicity (72 h exposure) to Chinese hamster ovary (CHO) cells was DBNM > DBCNM > BNM > TBNM > BDCNM > BCNM > DCNM > CNM > TCNM. The rank order to induce genomic DNA damage in CHO cells was DBNM > BDCNM > TBNM > TCNM > BNM > DBCNM > BCNM > DCNM > CNM. The brominated nitromethanes were more cytotoxic and genotoxic than their chlorinated analogues. This research demonstrated the integration of the procedures for the analytical chemistry and analytical biology when working with limited amounts of sample. The halonitromethanes are potent mammalian cell cytotoxins and genotoxins and may pose a hazard to the public health and the environment.

Inhibition of Testicular Steroidogenesis by the Xenoestrogen Bisphenol A Is Associated with Reduced Pituitary Luteinizing Hormone Secretion and Decreased Steroidogenic Enzyme Gene Expression in Rat Leydig Cells

Abstract: Exposure of humans to bisphenol A (BPA), a monomer in polycarbonate plastics and a constituent of resins used in food packaging and dentistry, is significant. In this report exposure of rats to 2.4 microg/kg.d (a dose that approximates BPA levels in the environment) from postnatal d 21-35 suppressed serum LH (0.21 +/- 0.05 ng/ml; vs. control, 0.52 +/- 0.04; P < 0.01) and testosterone (T) levels (1.62 +/- 0.16 ng/ml; vs. control, 2.52 +/- 0.21; P < 0.05), in association with decreased LHbeta and increased estrogen receptor beta pituitary mRNA levels as measured by RT-PCR. Treatment of adult Leydig cells with 0.01 nm BPA decreased T biosynthesis by 25% as a result of decreased expression of the steroidogenic enzyme 17alpha-hydroxylase/17-20 lyase. BPA decreased serum 17beta-estradiol levels from 0.31 +/- 0.02 ng/ml (control) to 0.22 +/- 0.02, 0.19 +/- 0.02, and 0.23 +/- 0.03 ng/ml in rats exposed to 2.4 microg, 10 microg, or 100 mg/kg.d BPA, respectively, from 21-35 d of age (P < 0.05) due to its ability to inhibit Leydig cell aromatase activity. Exposures of pregnant and nursing dams, i.e. from gestation d 12 to postnatal d 21, decreased T levels in the testicular interstitial fluid from 420 +/- 34 (control) to 261 +/- 22 (P < 0.05) ng/ml in adulthood, implying that the perinatal period is a sensitive window of exposure to BPA. As BPA has been measured in several human populations, further studies are warranted to assess the effects of BPA on male fertility.

Blood organic mercury and dietary mercury intake: National Health and Nutrition Examination Survey, 1999 and 2000.

Abstract: Blood organic mercury (i.e., methyl mercury) concentrations among 1,709 women who were participants in the National Health and Nutrition Examination Survey (NHANES) in 1999 and 2000 (1999-2000 NHANES) were 0.6 microg/L at the 50th percentile and ranged from concentrations that were nondetectable (5th percentile) to 6.7 microg/L (95th percentile). Blood organic/methyl mercury reflects methyl mercury intake from fish and shellfish as determined from a methyl mercury exposure parameter based on 24-hr dietary recall, 30-day food frequency, and mean concentrations of mercury in the fish/shellfish species reported as consumed (multiple correlation coefficient > 0.5). Blood organic/methyl mercury concentrations were lowest among Mexican Americans and highest among participants who designated themselves in the Other racial/ethnic category, which includes Asians, Native Americans, and Pacific Islanders. Blood organic/methyl mercury concentrations were ~1.5 times higher among women 30-49 years of age than among women 16-29 years of age. Blood mercury (BHg) concentrations were seven times higher among women who reported eating nine or more fish and/or shellfish meals within the past 30 days than among women who reported no fish and/or shellfish consumption in the past 30 days. Blood organic/methyl mercury concentrations greater than or equal to 5.8 microg/L were lowest among Mexican Americans (2.0%) and highest among examinees in the Other racial/ethnic category (21.7%). Based on the distribution of BHg concentrations among the adult female participants in 1999-2000 NHANES and the number of U.S. births in 2000, > 300,000 newborns each year in the United States may have been exposed in utero to methyl mercury concentrations higher than those considered to be without increased risk of adverse neurodevelopmental effects associated with methyl mercury exposure.

Chemical and Biological Characterization of Newly Discovered Iodoacid Drinking Water Disinfection Byproducts

Abstract: Iodoacid drinking water disinfection byproducts (DBPs) were recently uncovered in drinking water samples from source water with a high bromide/iodide concentration that was disinfected with chloramines. The purpose of this paper is to report the analytical chemical identification of iodoacetic acid (IA) and other iodoacids in drinking water samples, to address the cytotoxicity and genotoxicity of IA in Salmonella typhimurium and mammalian cells, and to report a structure−function analysis of IA with its chlorinated and brominated monohalogenated analogues. The iodoacid DBPs were identified as iodoacetic acid, bromoiodoacetic acid, (Z)- and (E)-3-bromo-3-iodopropenoic acid, and (E)-2-iodo-3-methylbutenedioic acid. IA represents a new class (iodoacid DBPs) of highly toxic drinking water contaminants. The cytotoxicity of IA in S. typhimurium was 2.9× and 53.5× higher than bromoacetic acid (BA) and chloroacetic acid (CA), respectively. A similar trend was found with cytotoxicity in Chinese hamster ovary (CHO)...

Hair mercury levels in U.S. children and women of childbearing age: reference range data from NHANES 1999-2000.

Abstract: Exposure to methyl mercury, a risk factor for neurodevelopmental toxicity, was assessed in U.S. children 1-5 years of age (n = 838) and women 16-49 years of age (n = 1,726) using hair mercury analysis during the 1999-2000 National Health and Nutrition Examination Survey (NHANES). The data are nationally representative and are based on analysis of cross-sectional data for the noninstitutionalized, U.S. household population. The survey consisted of interviews conducted in participants' homes and standardized health examinations conducted in mobile examination centers. Distributions of total hair mercury levels expressed as micrograms per gram hair Hg and the association of hair Hg levels with sociodemographic characteristics and fish consumption are reported. Geometric mean (standard error of the geometric mean) hair mercury was 0.12 microg/g (0.01 microg/g) in children, and 0.20 microg/g (0.02 microg/g) in women. Among frequent fish consumers, geometric mean hair mercury levels were 3-fold higher for women (0.38 vs. 0.11 micro g/g) and 2-fold higher for children (0.16 vs. 0.08 microg/g) compared with nonconsumers. The NHANES 1999-2000 data provide population-based data on hair mercury concentrations for women and children in the United States. Hair mercury levels were associated with age and fish consumption frequency.

A comparison of the power of the t test, Mann-Kendall and bootstrap tests for trend detection / Une comparaison de la puissance des tests t de Student, de Mann-Kendall et du bootstrap pour la détection de tendance

Abstract: Monte Carlo simulation is applied to compare the power of the statistical tests: the parametric t test, the non-parametric Mann-Kendall (MK), bootstrap-based slope (BS-slope), and bootstra...

Phthalate-induced Leydig cell hyperplasia is associated with multiple endocrine disturbances.

Abstract: The possibility that exposures to environmental agents are associated with reproductive disorders in human populations has generated much public interest recently. Phthalate esters are used most commonly as plasticizers in the food and construction industry, and di-(2-ethylhexyl) phthalate (DEHP) is the most abundant phthalate in the environment. Daily human exposure to DEHP in the U.S. is significant, and occupational and clinical exposures from DEHP-plasticized medical devices, e.g., blood bags, hemodialysis tubing, and nasogastric feeding tubes, increase body burden levels. We investigated the effects of chronic exposures to low environmentally relevant DEHP levels on testicular function. Our data show that prolonged exposures to this agent induced high levels of the gonadotropin luteinizing hormone and increased the serum concentrations of sex hormones [testosterone and 17β-estradiol (E2)] by >50%. Increased proliferative activity in Leydig cells was evidenced by enhanced expression of cell cycle proteins, as determined by RT-PCR. The numbers of Leydig cells in the testis of DEHP-treated rats were 40–60% higher than in control rats, indicating induction of Leydig cell hyperplasia. DEHP-induced elevations in serum testosterone and E2 levels suggest the possibility of multiple crosstalks between androgen, estrogen, and steroid hormone receptors, whereas the presence of estrogen receptors in nonreproductive tissues, e.g., cardiovascular system and bones, implies that the increases in serum E2 levels have implications beyond reproduction, including systemic physiology. Analysis of the effects of phthalate exposures on gonadotropin and steroid hormone levels should form part of overall risk assessment in human populations.

Comparison of spatial interpolation methods for the estimation of air quality data

Abstract: We recognized that many health outcomes are associated with air pollution, but in this project launched by the US EPA, the intent was to assess the role of exposure to ambient air pollutants as risk factors only for respiratory effects in children. The NHANES-III database is a valuable resource for assessing children's respiratory health and certain risk factors, but lacks monitoring data to estimate subjects' exposures to ambient air pollutants. Since the 1970s, EPA has regularly monitored levels of several ambient air pollutants across the country and these data may be used to estimate NHANES subject's exposure to ambient air pollutants. The first stage of the project eventually evolved into assessing different estimation methods before adopting the estimates to evaluate respiratory health. Specifically, this paper describes an effort using EPA's AIRS monitoring data to estimate ozone and PM10 levels at census block groups. We limited those block groups to counties visited by NHANES-III to make the project more manageable and apply four different interpolation methods to the monitoring data to derive air concentration levels. Then we examine method-specific differences in concentration levels and determine conditions under which different methods produce significantly different concentration values. We find that different interpolation methods do not produce dramatically different estimations in most parts of the US where monitor density was relatively low. However, in areas where monitor density was relatively high (i.e., California), we find substantial differences in exposure estimates across the interpolation methods. Our results offer some insights into terms of using the EPA monitoring data for the chosen spatial interpolation methods.

The LCIA midpoint-damage framework of the UNEP/SETAC Life Cycle Initiative

Abstract: Life Cycle Impact Assessment (LCIA) methods can be grouped into two families: classical methods determining impact category indicators at an intermediate position of the impact pathways (e.g. ozone depletion potentials) and damage-oriented methods aiming at more easily interpretable results in the form of damage indicators at the level of the ultimate societal concern (e.g. human health damage). The Life Cycle Initiative, a joint project between UNEP1 and SETAC2, proposes a comprehensive LCA framework to combine these families of methods. The new framework takes a world-wide perspective, so that LCA will progress towards a tool meeting the needs of both developing and developed countries. By a more precise and broadly agreed description of main framework elements, the Life Cycle Initiative expects to provide a common basis for the further development of mutually consistent impact assessment methods. Inputs to the LCIA midpoint-damage framework are results of Life Cycle Inventory analyses (LCI). Impact pathways connect the LCI results to the midpoint impact categories with the corresponding indicators, as well as to the damage categories at the level of damages to human health, natural environment, natural resources and man-made environment, via damage indicators. Mid-point impact categories simplify the quantification of these impact pathways where various types of emissions or extractions can be aggregated due to their comparable impact mechanisms. Depending on the available scientific information, impact pathways may be further described up to the level of damage categories by quantitative models, observed pathways or merely by qualitative statements. In the latter case, quantitative modelling may stop at mid-point. A given type of emission may exert damaging effects on multiple damage categories, so that a corresponding number of impact pathways is required. Correspondingly, a given damage category may be affected jointly by various types of emissions or extractions. It is therefore an important task of the Life Cycle Initiative to carefully select damage indicators. The content of the midpoint and of the damage categories is clearly defined, and proposals are made on how to express the extent of environmental damage by suitable indicator quantities. The present framework will offer the practitioner the choice to use either midpoint or damage indicators, depending on modelling uncertainty and increase in results interpretability. Due to the collaboration of acknowledged specialists in environmental processes and LCIA around the globe, it is expected that - after a few years of effort - the task forces of the Life Cycle Initiative will provide consistent and operational sets of methods and factors for LCIA in the future.

Children's behavior and physiology and how it affects exposure to environmental contaminants

Abstract: Infant, child, and adolescent exposures to environmental toxicants are different from those of adults because of differences in behavior and physiology. Because of these differences, there is the potential for quantitatively different exposures at various stages of development. Pediatricians are well aware of these behavioral and physiologic differences from a clinical standpoint--namely, food and water intake, soil ingestion, mouthing behavior, inhalation physiology, and activity level--as they relate to the ratio of these parameters between the adult and the child when considering weight and surface area. Pediatricians recognized the importance of pica as a cause of lead poisoning, the noxious effect of second-hand smoke, and the greater propensity for addiction during the adolescent years. For determining the differences in impact of many environmental toxicants between adults and children, research is needed to document where and whether these differences result in deleterious effects.

Assessment of a δ15N Isotopic Method to Indicate Anthropogenic Eutrophication in Aquatic Ecosystems

Abstract: Increased anthropogenic delivery of nutrients to water bodies, both freshwater and estuarine, has caused detrimental changes in habitat, food web structure, and nutrient cycling. Nitrogen-stable isotopes may be suitable indicators of such increased nutrient delivery. In this study, we looked at the differences in response of macrophyte delta15N values to anthropogenic N across different taxonomic groups and geographic regions to test a stable isotopic method for detecting anthropogenic impacts. Macrophyte delta15N values increased with wastewater input and water-column dissolved inorganic nitrogen (DIN) concentration. When macrophytes were divided into macroalgae and plants, they responded similarly to increases in wastewater N, although macroalgae was a more reliable indicator of both wastewater inputs and water-column DIN concentrations. Smooth cordgrass (Spartina alterniflora Loisel.) Delta15N increased uniformly with wastewater inputs across a geographic range. We used the relationship derived between S. alterniflora and relative wastewater load to predict wastewater loads in locations lacking quantitative land use data. The predictions matched well with known qualitative information, proving the use of a stable isotopic method for predicting wastewater input.