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PubMedDate not supplied

Using objective and subjective information to develop distributions for probabilistic exposure assessment.

The propagation of variance through complex exposure models has been simplified by simulation software running on desktop computers; however, the appropriate representation of variability in, and uncertainty about, model inputs remains a challenge. The U.S. Environmental Protection Agency (EPA) has indicated that the Monte Carlo simulation approach to exposure assessment is acceptable as long as input distributions are credible, i.e., rooted in fact (EPA, 1992). The use of distributions based on empirical evidence is certainly desirable; however, it is not always possible to obtain measurements for all exposure model inputs under the conditions of interest. Where objective evidence is scarce or unavailable, subjective judgments are necessary. In this work, the application of both statistical and subjective approaches to the development of distributions for exposure model inputs is explored. The consequences of one's approach to distribution development, on the interpretation and applicability of the output, are also considered.

Data Interpretation, Statistical↗
PubMed2006

Biodegradation kinetics of linear alkylbenzene sulphonates in sea water.

This article reports the primary biodegradation kinetics of linear alkylbenzene sulphonates (LAS) in sea water from the Bay of Cadiz (South West of the Iberian Peninsula). The authors used the biodegradation test guideline proposed by the Office of Prevention, Pesticides, and Toxic Substances of the United States Environmental Protection Agency; 835.3160 "Biodegradability in sea water" in its shake flask variant. High performance liquid chromatography (HPLC) has been employed for the analysis of the surfactant material. The surfactant shows a primary biodegradation kinetic in accordance with a logistic model, the kinetic parameters t (50) and lag time were calculated by means of a easy quantitative procedure introduced. Mean values of 6.15 +/- 0.45 and 6.67 +/- 0.6 days were obtained for t (50) and lag time, respectively. These results indicate that although LAS has a high primary biodegradation rate in sea water, it biodegrades slower than in similar tests conducted in river water.

Alkanesulfonic Acids↗
PubMed1990

An examination of the intra-SMSA distribution of carbon monoxide exposure.

Although fixed-site monitoring data have been used to estimate the spatial pattern of human exposure, the intra-urban distribution of actual exposure has not been documented. This paper used the data collected during the Environmental Protection Agency's (EPA) field investigation of personal exposure to carbon monoxide (CO) to investigate the nature of the distribution of CO with respect to residential location in the Washington, D.C. SMSA. Dot-distribution maps and analysis of variance were used to document the spatial pattern of individual-level in-home CO concentrations. The results show sampled individuals living in the SMSA center are exposed to statistically significantly higher levels of CO than are those living in the suburbs. The most important implications of this work are for exposure modeling. Further investigation is needed to determine whether incorporation of a geographic component will improve exposure prediction.

Carbon Monoxide↗
PubMed1997

The application of exposure-based criteria in developing alternative primary ambient ozone standards.

The form of the primary National Ambient Air Quality Standard (NAAQS) for ozone has been a matter of some concern in recent years. The Environmental Protection Agency is reviewing the ozone NAAQS and has proposed a set of alternative standards that address some deficiencies. However, the proposed alternatives are all based upon the ozone concentrations occurring at the peak monitor, which may not be representative of the air quality and population exposure throughout a nonattainment area. Representativeness could be improved by converting the form of the standard from an exceedance-based metric (with x allowable exceedances per year, on average) to one based upon exposure. Three approaches to defining an exposure-based standard are developed here. Data from the San Francisco Bay area are used to illustrate the proposed standards.

Air Pollutants, Occupational↗
PubMed1998

Environmental complex mixture toxicity assessment.

Trichloroethylene (TCE) was found as a contaminant in the well supplying water to an aquatic testing laboratory. The groundwater was routinely screened by a commercial laboratory for volatile and semivolatile compounds, metals, herbicides, pesticides, and polychlorinated biphenyls using U.S. Environmental Protection Agency methods. Although TCE was the only reportable peak on the gas chromatograph, with average concentrations of 0.200 mg/l, other small peaks were also present, indicating the possibility that the contamination was not limited to TCE alone. A chronic 6-month carcinogenicity assay was conducted on-site in a biomonitoring trailer, using the Japanese medaka fish (Oryzias latipes) in an initiation-promotion protocol, with diethylnitrosamine (DEN) as the initiator and the TCE-contaminated groundwater as a promoter. Study results indicated no evidence of carcinogenic potential of the groundwater without initiation. There was, however, a tumor-promotional effect of the groundwater after DEN initiation. A follow-up laboratory study was conducted using reagent grade TCE added to carbon-filtered groundwater to simulate TCE concentrations comparable to those found in the contaminated groundwater. Study results indicated no promotional effects of TCE. These studies emphasize the necessity for on-site bioassays to assess potential environmental hazards. In this instance, chemical analysis of the groundwater identified TCE as the only reportable contaminant, but other compounds present below reportable limits were noted and may have had a synergistic effect on tumor promotion observed with the groundwater exposure. Laboratory toxicity testing of single compounds can produce toxicity data specific to that compound for that species but cannot take into account the possible toxic effects of mixtures of compounds.

Adenoma, Liver Cell↗
PubMedDate not supplied

Respiratory effects of air pollutants among asthmatics in central Taiwan.

The authors investigated the relationship between respiratory effects and air pollutants among asthmatics in central Taiwan. A total of 12,926 subjects were selected from 8 junior high schools. Data about monthly hospital admissions for respiratory illnesses were collected over a period of 1 yr from the National Insurance Bureau. Data included how frequently subjects purchased medication and the respiratory symptoms recorded by clinic and hospital personnel. Pulmonary function tests were administered to 20% of the total study population, which was selected randomly. Data about monthly levels of air pollutants (i.e., particulate matter 10 pm and less [PM10], ozone [O3], sulfur dioxide [SO2], and nitrogen dioxide [NO2]) were provided by Taiwan's Environmental Protection Agency. The prevalence rates of asthma were correlated significantly with NO2 (r = .63) and 03 (r = .51) concentrations. Levels of NO2 and PM10 were correlated significantly with monthly hospital admissions. Forced vital capacity, forced expiratory volume in 1 sec, and peak expiratory flow for asthmatics in central Taiwan were 6-11% lower than normal predicted values for the general Taiwanese student population, adjusted for age, height, and weight. In conclusion, the increased risk of asthma and the frequency of monthly hospital admissions among asthmatics may be correlated positively with pollution levels-especially NO2 and PM10. air pollutants, asthma, mon

Adolescent↗
PubMed1998

Interactions between metals and microbial communities in New Bedford Harbor, Massachusetts.

The fate of toxic metals in marine sediments depends on a combination of the physical, chemical, and biologic conditions encountered in any given environment. These conditions may vary dramatically, both spatially and temporally, in response to factors ranging from seasonal changes and storm events to human activities such as dredging or remediation efforts. This paper describes a program designed to evaluate the interrelationships between the microbial community and pollutants in the New Bedford Harbor, Massachusetts, area, a U.S. Environmental Protection Agency designated Superfund site. Research has focused on establishing distributional relationships between contaminant metals, fluxes of metals between sediments and the overlying water, changes in microbial diversity in response to metals, and potential use of the microbial community as a biomarker of contaminant availability. This research has shown that a significant flux of metals to the water column is mediated by benthic biologic activity, and that microbial communities may be a responsive marker of contaminant stress. A combination of biogeochemical studies and the use of molecular tools can be used to improve our understanding of the fate and effect of heavy metals released to aquatic systems.

Animals↗
PubMed2006

Effects of time and point-of-use devices on arsenic levels in Southeastern Michigan drinking water, USA.

Health effects associated with chronic, low-level exposures to arsenic in drinking water (<100 microg/L) remain unclear, in part due to uncertainties in assessing exposure. Drinking water concentrations have been used to assess past exposure to arsenic in epidemiological studies, under the assumption that a single measurement can be used to estimate historical exposure. This study aims to better understand (1) temporal variability in arsenic concentrations in drinking water and (2) the impact of point-of-use (POU) treatment devices on arsenic exposure measurements, and on reliability of the exposure measurement for population-level studies. Multiple drinking water samples were collected at two points in time (an average of fourteen months apart) for 261 individuals enrolled in a case-control study of arsenic exposure and bladder cancer in Michigan. Sources of drinking water included private wells (n = 221), public water supplies (n = 33), and bottled water (n = 7); mean arsenic concentration was highest in private wells (7.28 microg/L) and lowest in bottled water samples (0.28 microg/L). Arsenic concentrations in primary drinking water samples were highly correlated (r = 0.88, p < 0.0001, n = 196), with 3% of the water sources exceeding the United States Environmental Protection Agency's Maximum Contaminant Level (MCL) in one sample but not in the other sample. Measurement reproducibility did not vary by type of POU device (e.g., softener, filter, reverse osmosis system). Arsenic concentrations did differ, however, between samples treated with POU devices and untreated samples taken on the same day. Substantial differences in arsenic concentrations were consistently observed for reverse osmosis systems; other POU devices had variable effects on arsenic concentrations. These results indicate that while a single residential arsenic measurement may be used to represent exposure in this region, researchers must obtain information on changes in water source and POU treatment devices to better characterize population exposures over time.

Arsenic↗
PubMed2003

Evaluation of two methods for prediction of bioaccumulation factors.

Two methods for deriving bioaccumulation factors (BAFs) used by the U.S. Environmental Protection Agency in development of water quality criteria were evaluated using polychlorinated biphenyl (PCB) data from the Hudson River and Green Bay ecosystems. One method predicts BAF(L)fd values (BAFs based upon concentrations of freely dissolved chemical in ambient water and in the lipid fraction of tissue) using field-measured biota-sediment accumulation factors (BSAFs): greater than 90% of the predicted BAF(L)fd values were within a factor of 5 of their measured values for both ecosystems. The second method predicts BAF(L)fd values as the chemical's 1-octanol/water partition coefficient (Kow) times a food chain multiplier: greater than 90% of the predicted BAF(L)fd values were within a factor of 5 of their measured values for the Green Bay ecosystem and for three of the six sampling locations on the Hudson River. Poorer predictive ability with the Kow method for the other three sampling locations was believed to be due to the existence of environmental conditions not representative of the longer term ecosystem conditions assumed for the method. BAF(L)fd and BAF(T)t values (BAFs based upon concentrations of total chemical in ambient water and in wet tissue) were compared. The within ecosystem and across ecosystems comparisons demonstrated a 2-5-fold decrease in variability (expressed as ratios of coefficients of variation, percentile ranges, and confidence ranges) for predicted BAF(L)fd values in comparison to BAF(T)t values.

Adipose Tissue↗
PubMed2001

Control of chemical risks during the treatment of soil contaminated with chlorophenol, creosote and copper-chrome-arsenic-wood preservatives.

BACKGROUND: Exposure to chemicals in polluted soil was studied during the remediation of four polluted sites. They are sawmill areas contaminated with chlorophenols and polychlorinated dibenzo-p-dioxins and furanes (PCDD/F), wood impregnating plants contaminated with polycyclic aromatic hydrocarbons (PAH) from creosote oil, old gas works area contaminated with PAH, and a wood impregnation plant contaminated with copper-chromium-arsenic (CCA) preservative. METHODS: The exposure levels were determined by both air and biological monitoring. RESULTS: Air monitoring showed that the exposure levels were generally well below the current occupational exposure limits. The calculations indicated, however, that the lowest acceptable daily intake value recommended for PCDD/F by the U.S. Environmental Protection Agency was exceeded. Chlorophenol exposure was generally low. Exposure to volatile PAH was 0.038-0.884 mg/m(3) and that to particulate PAH was 0.004-0.183 mg/m(3). The biomonitoring results (urinary 1-pyrenol) suggested that some exposure occurs, probably through the contamination of hands or skin absorption. At the sites contaminated with CCA salts, no exposure limits were exceeded. CONCLUSIONS: The results generally suggest that the exposure of cleanup workers is generally below the current occupational exposure limits but that short-term high exposure cannot be excluded. There was also some indication of poor skin protection, which should be improved when soil contaminated with PAH and creosote oil is handled.

Arsenic↗
PubMed2003

Health implications of exposure to environmental nitrogenous compounds.

All living systems need nitrogen for the production of complex organic molecules, such as proteins, nucleic acids, vitamins, hormones and enzymes. Due to the intense use of synthetic nitrogen fertilisers and livestock manure in modern day agriculture, food (particularly vegetables) and drinking water may contain higher concentrations of nitrate than in the past. The mean intake of nitrate per person in Europe is about 50-140 mg/day and in the US about 40-100 mg/day. In the proximal small intestine, nitrate is rapidly and almost completely absorbed (bioavailability at least 92%). In humans, approximately, 25% of the nitrate ingested is secreted in saliva, where some 20% (about 5-8% of the nitrate intake) is converted to nitrite by commensal bacteria. The nitrite so formed is then absorbed primarily in the small intestine. Nitrate may also be synthesised endogenously from nitric oxide (especially in case of inflammation), which reacts to form nitrite. Normal healthy adults excrete in the urine approximately 62 mg nitrate ion/day from endogenous synthesis. Thus, when nitrate intake is low and there are no additional exogenous sources (e.g. gastrointestinal infections), the endogenous production of nitrate is more important than exogenous sources. Nitrate itself is generally regarded nontoxic. Toxicity is usually the result of the conversion of nitrate into the more toxic nitrite. There are two major toxicological concerns regarding nitrite. First, nitrite may induce methaemoglobinaemia, which can result in tissue hypoxia, and possibly death. Secondly, nitrite may interact with secondary or N-alkyl-amides to form N-nitroso carcinogens. However, epidemiological investigations and human toxicological studies have not shown an unequivocal relationship between nitrate intake and the risk of cancer. The Joint Expert Committee of the Food and Agriculture Organization of the United Nations/World Health Organization (JECFA) and the European Commission's Scientific Committee on Food have set an acceptable daily intake (ADI) for nitrate of 0-3.7 mg nitrate ion/kg bodyweight; this appears to be safe for healthy neonates, children and adults. The same is also true of the US Environmental Protection Agency (EPA) Reference Dose (RfD) for nitrate of 1.6 mg nitrate nitrogen/kg bodyweight per day (equivalent to about 7.0 mg nitrate ion/kg bodyweight per day). This opinion is supported by a recent human volunteer study in which a single dose of nitrite, equivalent to 15-20 times the ADI for nitrate, led to only mild methaemoglobinaemia (up to 12.2%), without other serious adverse effects. The JECFA has proposed an ADI for nitrite of 0-0.07 mg nitrite ion/kg bodyweight and the EPA has set an RfD of 0.1 mg nitrite nitrogen/kg bodyweight per day (equivalent to 0.33 mg nitrite ion/kg bodyweight per day). These values are again supported by human volunteer studies.

Animals↗
PubMed2005

Pediatric melanoma: risk factor and survival analysis of the surveillance, epidemiology and end results database.

PURPOSE: To evaluate risk factors for the development of and factors influencing survival in pediatric melanoma. PATIENTS AND METHODS: We evaluated 1,255 children (age < 20 years) and 2,673 young adults (age 20 to 24 years) with melanoma in the 2001 National Cancer Institute (NCI) Surveillance, Epidemiology and End Results (SEER) database. We estimated exposure to UV radiation based on Environmental Protection Agency (EPA) measurements. RESULTS: The incidence of pediatric melanoma increased 46% (95% CI, 40 to 52) per year of age and 2.9% (95% CI, 2.1 to 3.6) per year from 1973 to 2001. Incidence rates were lower in black patients (-95%; 95% CI, -98 to -90) compared with white patients and in male patients (-39%; 95% CI -46 to -31) compared with females. Increased ambient UV radiation was associated with elevated risk (19% per kJ; 95% CI, 9 to 30). Children with melanoma had a 5-year melanoma-specific survival of 93.6% (95% CI, 91.9 to 94.9), which improved from 1973 to 2001. The hazard ratio of death from melanoma increased with male sex; older age; advanced disease; location of the primary other than extremities or torso; earlier year of diagnosis; and previous cancer. CONCLUSION: The incidence of melanoma in the United States is increasing rapidly in children. Risk factors for pediatric melanoma include being white, being female, increasing age, and environmental UV radiation. Survival is decreased for children and adolescents with unfavorable prognostic factors (male sex, unfavorable site, and/or second primary or regional or distant metastasis). More effective therapeutic strategies are needed for these groups.

Adult↗
PubMed2006

PAH-concentrations and compositions in the top 2 cm of forest soils along a 120 km long transect through agricultural areas, forests and the city of Oslo, Norway.

The top 2 cm of forest soils were collected along a 120 km long south-north transect running through Norway's largest city Oslo. Forty samples were analysed for their polycyclic aromatic hydrocarbon (PAH(16) as defined by the U.S. Environmental Protection Agency) concentrations and compositions. Local variations in the PAH values are high and the reported concentrations are in general low (maximum sumPAH16: 2.6 mg/kg). The transect shows distinct differences of sumPAH16 values from south to north. PAH concentrations are substantially lower in the less populated areas at the north end of the transect than at the urbanised and much more populated south end. Several high values occur in a forested area to the north of Oslo, used for recreation purposes. The PAH distribution patterns point towards a predominantly pyrogenic origin. Local Cambrian carbon-rich black shales can be excluded as sources for PAHs in the forest soils.

Agriculture↗
PubMedDate not supplied

The quality management system as a tool for improving stakeholder confidence.

The Corps of Engineers works with local restoration advisory boards (RAB) to exchange information and develop plans for restoration of closed military bases for civilian reuse. Meetings of the RAB to discuss progress in environmental assessment and restoration of former defense sites can be contentious due to the complex technical nature of the information to be shared and the personal stake that the members of the community have in ensuring that contentious areas are restored for safe use. A prime concern of community representatives is often the quality of the data used to make environmental decisions. Laboratory case narratives and data flags may suggest laboratory errors and low data quality to those without an understanding of the information's full meaning. RAB members include representatives from local, state, and tribal governments, the Department of Defense, the Environmental Protection Agency, and the local community. The Corps of Engineers representatives usually include project technical and management personnel, but these individuals may not have sufficient expertise in the project quality assurance components and laboratory data quality procedures to completely satisfy community concerns about data quality. Communication of this information to the RAB by a quality assurance professional could serve to resolve some of the questions members have about the quality of acquired data and proper use of analytical results, and increase community trust that appropriate decisions are made regarding restoration. Details of the effectiveness of including a quality assurance professional in RAB discussions of laboratory data quality and project quality management are provided in this paper.

Community Participation↗
PubMed2005

A dispersion modelling approach to determine the odour impact of intensive poultry production units in Ireland.

The use of atmospheric dispersion modelling has become more common for the determination of odour impacts from existing poultry production facilities and the assessment of setback distances for new facilities. Setback distances for broiler, layer and turkey units were determined using the atmospheric dispersion model ISCST3 and the Environmental Protection Agency (EPA, Ireland) recommended criterion (C(98,1-h)6.0 ou(E) m(-3)) and a new odour annoyance criterion (C(98,1-h) 9.7 ou(E) m(-3)) developed in this study. For a typical size unit in Ireland, maximum setback distances of 660, 665 and 1035 m were calculated for 40,000 broilers, 40,000 layers and 10,000 turkeys respectively at the current limit (C(98,1-h) 6.0 ou(E) m(-3)). However, if the suggested odour impact criterion (C(98,1-h) 9.7 ou(E) m(-3)) is implemented, the maximum setback distances decrease to 460, 500 and 785 m for broilers, layers and turkeys, respectively.

Animal Husbandry↗
PubMed2001

Comparison and evaluation of laboratory performance on a method for the determination of perchlorate in fertilizers.

This report details the interlaboratory validation of a method for the determination of perchlorate in fertilizers. In this method (EPA/600/R-01/026), a solid sample of fertilizer is ground. Subsequently, the ground material is either leached with deionized water to dissolve any perchlorate salt in the case of minimally soluble fertilizers (e.g. supertriplephosphate or timed-release products), or simply dissolved in the case of highly soluble fertilizers (e.g. urea, NaNO3 or KCl). The resulting aqueous solution is then subjected to ion chromatography with suppressed conductivity detection. Four laboratories applied the method to field samples of 48 different products (commodity chemicals) and to seven quality control samples prepared by the Environmental Protection Agency (EPA). Additional tests were conducted by three other laboratories on specific materials. Recovery (81-111%) was demonstrated on spikes of known concentration, and a preliminary assured reporting level was determined for each fertilizer matrix by each laboratory. Injection-to-injection precision was satisfactory: generally less than 15% difference, and always less than 25%. All of the laboratories used Dionex IonPac AG16 guard and AS16 separation columns with NaOH or KOH as eluent. Detection was by suppressed conductivity. The method was shown to be sufficiently robust for the screening of fertilizers for perchlorate, but performance was low on a mixture of siliceous minerals (kaolinite and bentonite). Both laboratory performance and method performance are validated.

Calibration↗
PubMed2002

Androgens and environmental antiandrogens affect reproductive development and play behavior in the Sprague-Dawley rat.

In mammals, exposure to androgens early in development is essential for masculinization of the male reproductive phenotype. Male fetuses exposed to antiandrogens during perinatal life are permanently demasculinized in their morphology and physiology, whereas exposure to exogenous androgens permanently masculinizes females. In some litter-bearing species, proximity(italic) in utero(/italic) of females to males can partially masculinize female siblings and alter their responsiveness to endocrine-disrupting compounds. However, in our strain of rat (CD-SD Charles River), intrauterine position does not significantly influence testosterone concentrations and anogenital distance of fetuses. In comparison, administration of testosterone propionate to pregnant females, at doses that doubled fetal female testosterone levels, did masculinize the reproductive system. Discovery of androgen-active chemicals in the environment has placed increased emphasis on describing the reproductive and behavioral effects of both natural and environmental androgens and antiandrogens. Recently, the effects of an antiandrogen, vinclozolin, on the brain and behavior were cited as a special concern by the U.S. Environmental Protection Agency in its risk assessment of this pesticide. In rats, one such behavior that is perinatally organized by androgens is social play. Males play more than females, and administration of exogenous androgens during the neonatal period alters the juvenile expression of this sexually dimorphic behavior. Vinclozolin is an androgen receptor antagonist that inhibits androgen-dependent tissue growth in vivo. We were interested in whether developmental exposure to vinclozolin could also alter androgen-dependent behaviors such as play. Neonatal male rats were injected on postnatal days (PNDs) 2 and 3 with corn oil, the pharmacologic antiandrogen flutamide (50 mg/kg), or vinclozolin (200 mg/kg). On PNDs 36-37 animals were observed for social play. Behaviors associated with general social activity such as sniffing and dorsal contact were unaffected by treatment. However, play behavior in males treated with flutamide or vinclozolin was significantly reduced, resembling levels of play characteristic of females rather than untreated males. Therefore, this study demonstrates that perinatal exposure to vinclozolin, an environmental antiandrogen, can alter androgen-dependent play behavior in the male rat.

Androgen Antagonists↗
PubMed1998

Uses and limits of empirical data in measuring and modeling human lead exposure.

This paper examines the uses and limits of empirical data in evaluating measurement and modeling approaches to human lead exposure. Empirical data from experiment or observation or both have been used in studies of lead exposure. For example, experimental studies have elucidated and quantified physiologic or biokinetic parameters of lead exposure under controlled conditions. Observation, i.e., epidemiology, has been widely applied to study population exposures to lead. There is growing interest in the use of lead exposure prediction models and their evaluation before use in risk assessment. Empirical studies of lead exposure must be fully understood, especially their limits, before they are applied as "standards" or reference information for evaluation of exposure models, especially the U.S. Environmental Protection Agency's lead biokinetic model that is a focus of this article. Empirical and modeled datasets for lead exposure may not agree due to a) problems with the observational data or b) problems with the model; caution should be exercised before either a model or observational data are rejected. There are at least three sources of discordance in cases where there is lack of agreement: a) empirical data are accurate but the model is flawed; b) the model is valid but reference empirical data are inaccurate; or c) neither empirical data nor model is accurate, and each is inaccurate in different ways. This paper evaluates some of the critical empirical input to biokinetic models, especially lead bioavailability.

Animals↗