Maternal exposure to trichloroethylene in drinking water and birth-weight outcomes

An ecological epidemiological study was conducted with data obtained from an environmental dose-reconstruction study and the Arizona Birth Information Tapes. Before 1981, a portion of the city of Tucson water-distribution system was contaminated with trichloroethylene (i.e., < 5 micrograms per liter of water to 107 micrograms per liter of water). Target and comparison populations were selected with a Geographic Information System. Logistical-regression analysis revealed an association between maternal exposure to trichloroethylene via drinking water and very-low-birth-weight babies (i.e., < 1,501 grams) (odds ratio = 3.3; 95% confidence interval = 0.5, 20.6; and Wald chi-square p value = 0.2). No association was found between maternal exposure to trichloroethylene via drinking water and low birth weight or full-term low-birth-weight infants (gestational period > 35 wk and < 46 wk).     

Hydrogeologic assessment of exposure to solvent-contaminated drinking water: pregnancy outcomes in relation to exposure

We recently concluded that exposure to solvent-contaminated drinking water was an unlikely explanation for observed excesses of adverse pregnancy outcomes during 1980-1981 in the Los Paseos neighborhood of Santa Clara County, California, because these excesses were not observed in an adjacent exposed area. The validity of this conclusion depends on the assumption that the two areas had comparable exposure. Using quantitative methods to model movement of the solvent leak plume and water flow within the distribution system, we estimated that women with adverse outcomes were no more likely to have received contaminated water than women with normal live births. These results strengthen the conclusion that exposures to water from the contaminated well were not responsible for the excess of adverse outcomes observed in the Los Paseos area.     

Neonatal thyroxine level and perchlorate in drinking water

Environmental contamination of drinking water has been observed for perchlorate, a chemical able to affect thyroid function. This study examines whether that exposure affected the thyroid function of newborns. Neonatal blood thyroxine (T4) levels for days 1 to 4 of life were compared for newborns from the city of Las Vegas, Nevada, which has perchlorate in its drinking water, and those from the city of Reno, Nevada, which does not (detection limit, 4 micrograms/L [ppb]). This study is based on blood T4 analyses from more than 23,000 newborns in these two cities during the period April 1998 through June 1999. No difference was found in the mean blood T4 levels of the newborns from these two cities. Drinking water perchlorate levels measured monthly for Las Vegas ranged during this study period from non-detectable for 8 months to levels of 9 to 15 ppb for 7 months. Temporal differences in mean T4 level were noted in both cities but were unrelated to the perchlorate exposure. This study was sufficiently sensitive to detect the effects of gender, birth weight, and the day of life on which the blood sample was taken on the neonatal T4 level, but it detected no effect from environmental exposures to perchlorate that ranged up to 15 micrograms/L (ppb).     

A multi-route exposure assessment of chemically contaminated drinking water

This report provides an example of how a single source of contamination could potentially contribute to all routes of exposure. A modeling approach was used to estimate multiple exposure routes in an attempt to assess the health significance of gasoline-contaminated drinking water supplies. This model consisted of a two-compartment, indoor air quality equation that calculates the contribution made by ambient and indoor air contaminated by a pollutant volatilized from drinking water to that pollutant's inhalation burden. In addition, the model uses the traditional equations for assessing a pollutant's oral and dermal burdens. Benzene, toluene and xylene were used as surrogates for gasoline contamination to determine the contribution of contaminated water to adult and child body burdens from indoor air, oral (drinking water and food) and dermal exposure routes. The contribution thus calculated for each chemical was compared to the EPA's Office of Drinking Water Health Advisories. In terms of acute exposure, the use of chemically contaminated water for showering purposes may generate vapor in the confined area of the bathroom at levels sufficient to cause or contribute to mucous tissue irritation, as commonly reported in affected homes. High temperatures and humidity may also contribute to these effects, especially in the bathroom. In terms of chronic exposure, the use of chemically contaminated water at EPA-recommended guideline amounts in an affected home may result in inhalation, oral and dermal exposures leading to cumulative doses exceeding adult and child total daily body burdens based on EPA's Health Advisories. Thus, this model indicates that the traditional standard/guidelines derivation processes should be reevaluated to consider the pollutant contribution from multiple routes of exposure. The New Jersey Departments of Health and Environmental Protection conducted a study in which concentrations of several pollutants including benzene in the breathing zone were measured during a 15-minute shower in homes with contaminated water. The findings suggest that the air quality model used in the present study may satisfactorily predict the airborne concentrations of pollutants in, at least, the bathroom after showering with contaminated water (Pearson rank correlation coefficient of 0.773 with p = 0.0012 for n = 14). The findings of the present study support the use of an adjustment factor for all exposure durations to account for exposures to other sources of the contaminant, i.e., urban, occupational, and food. A value of 20% seems appropriate based on the study's findings.(ABSTRACT TRUNCATED AT 400 WORDS)     

Blink reflex latency after exposure to trichloroethylene in well water

The electrophysiological measurement of the blink reflex (BR) can quantify the conduction latency in the reflex arc involving the Vth (trigeminal) and VIIth (facial) cranial nerves. We measured the electrophysiological BR in a population (N = 21), which had alleged chronic exposure to trichloroethylene (TCE) through the public drinking water at levels 30-80 times higher than the Environmental Protection Agency (EPA) Maximum Contamination Level (MCL). A highly significant difference was observed in the conduction latency means of the BR components (p less than .0001), when the study population was compared with laboratory controls (N = 27). This difference suggests a subclinical alteration of the Vth cranial nerve function due to chronic, environmental exposure to TCE.     

Childhood cancer incidence and arsenic exposure in drinking water in Nevada

Inorganic arsenic exposure through drinking water causes cancer in adults; however, the carcinogenic potential in children remains unknown. A recent leukemia cluster in Churchill County, Nevada, where arsenic levels in water supplies are relatively high, has prompted concern. The authors investigated the incidence of childhood cancer between 1979 and 1999 in all 17 Nevada counties, grouped by low (i.e., < 10 microg/l), medium (10-25 microg/l), and high (35-90 microg/l) population-weighted arsenic levels in public drinking water supplies. The standardized incidence ratios (SIRs) for all childhood cancers combined were 1.00 (95% confidence interval [CI] = 0.94, 1.06), 0.72 (95% CI = 0.43, 1.12), and 1.25 (95% CI = 0.91, 1.69) for low-, medium-, and high-exposure counties, respectively. There was no relationship between arsenic levels in water and childhood leukemia (SIRs = 1.02, 0.61, and 0.86, respectively [95% CIIs = 0.90, 1.15; 0.12, 1.79; and 0.37, 1.70, respectively]). For all childhood cancers, excluding leukemias, the SIRs were 0.99 (95% CI = 0.92, 1.07), 0.82 (95% CI = 0.42, 1.22), and 1.37 (0.92, 1.83), respectively. The excess in 5- to 9-yr-old children and 10- to 14-yr-old children was in bone cancers, and the excess in 15- to 19-yr-old young adults was primarily in lymphomas. The findings in this study are reassuring in that leukemia risks were not increased at the concentrations of arsenic in water found in this study. Nonetheless, the results raise the possibility that there are increased risks for nonleukemic childhood cancers that require confirmation in other studies, particularly those in which higher exposures are addressed.     

Application of clearance concepts to the assessment of exposure to lead in drinking water.

This paper explores the application of clearance concepts to environmental toxicology. Lead, for which a clearance of about 0.5 ml/min is estimated from published data, is chosen as an example. An index for the contribution of drinking water to total exposure is developed using these concepts. For lead, this index is shown to increase with the concentration of the metal in water; it is higher for children than for adults. At the maximum contaminant level (MCL) of 10 micrograms/L proposed by the US Environmental Protection Agency (EPA), the average contribution from lead in drinking water is estimated to be 7 percent. The contribution in children is about twice as great. At and above the current MCL of 50 micrograms/L, drinking water becomes a major source of lead exposure.     

Multipathway risk assessment of trihalomethane exposure in drinking water of Lebanon

The toxicological risks and lifetime cancer risks of trihalomethanes through oral ingestion, dermal absorption, and inhalation exposure from tap water in selected regions in Lebanon are estimated. Existing trihalomethane concentrations do not pose any non-carcinogenic and developmental risks in the exposed population via oral ingestion. Among the three pathways, residents have a higher risk of cancer through oral ingestion than through the other two pathways. The lifetime cancer risk through oral ingestion for dibromochloromethane makes the highest contribution to total risks, followed by bromodichloromethane, bromoform, and chloroform. The total multipathway cancer risk analysis suggests that no cancer risks exist during the summer and winter seasons; however, in the spring the total cancer risks exceeds the USEPA acceptable level of 10^-6 by a factor of 10.7.     

Multipathway risk assessment of trihalomethane exposure in drinking water of Lebanon

The toxicological risks and lifetime cancer risks of trihalomethanes through oral ingestion, dermal absorption, and inhalation exposure from tap water in selected regions in Lebanon are estimated. Existing trihalomethane concentrations do not pose any non-carcinogenic and developmental risks in the exposed population via oral ingestion. Among the three pathways, residents have a higher risk of cancer through oral ingestion than through the other two pathways. The lifetime cancer risk through oral ingestion for dibromochloromethane makes the highest contribution to total risks, followed by bromodichloromethane, bromoform, and chloroform. The total multipathway cancer risk analysis suggests that no cancer risks exist during the summer and winter seasons; however, in the spring the total cancer risks exceeds the USEPA acceptable level of 10(-6) by a factor of 10.7.     

Human exposure to trihalomethanes in drinking water]

Halogenated hydrocarbon compounds, some of them recognized as carcinogenic to different animal species can be found in drinking water. Chloroform, bromodichloromethane, dibromochloromethane and bromoform are the most important trihalomethanes found in potable water. They are produced in natural waters during chlorinated desinfection by the halogenation of precursors, specially humic and fulvic compounds. The review, in the MEDLINE covers the period from 1974 to 1998, presents the general aspects of the formation of trihalomethanes, sources of human exposure and their toxicological meaning for exposed organisms: toxicokinetic disposition and spectrum of toxic effects (carcinogenic, mutagenic and teratogenic).     

Public exposure to 226Ra in drinking water

This paper presents a new method for calculating the effective dose of 226Ra regularly ingested with drinking water over a long period of time. The method is based on the assessment of cumulated 226Ra activity in the fraction retained in the whole body at time t (in days) after intake [so called m(t) value]. For modelling, simulation, and visualisation of the continuous intake of 226Ra by drinking water, we used the Simulink program package integrated with the Matlab. The dose assessment was performed for 226Ra activities of 5 mBq L(-1), 50 mBq L(-1), 1000 mBq L(-1) and 5000 mBq L(-1). The results suggest that 226Ra activities above 1000 mBq L(-1) produce effective doses which are below the recommended maximum. However, the potential effect of 226Ra activities of this extent is still unknown in children.     

离子色谱法测定饮用水中高氯酸盐含量研究

目的:建立一种简便快速梯度淋洗离子色谱法测定饮用水中高氯酸盐含量。方法:选用以高容量、强亲水性IonPac AS23阴离子分析柱,0 mmol/L~40 mmol/LKOH淋洗液,流速为1.0 m l/m in,电导检测器,样品经0.45μm滤膜过滤后直接进样。结果:本法相关性好(r=0.9998),相对标准偏差(RSD)为2.15%~5.99%,样品加标平均回收率为87.9%~101%,最低检出量为3.0μg/L。结论:该法操作简单、快速、准确、灵敏、适用于大批水样分析。     

A health risk assessment for exposure to trace metals via drinking water ingestion pathway

A health risk assessment was conducted for exposure to trace metals via drinking water ingestion pathway for Province of Izmir, Turkey. Concentrations of 11 trace metals were measured in drinking waters collected from 100 population weighted random sampling units (houses). The samples were analyzed in atomic absorption spectrometry for arsenic, and inductively coupled plasma-optical emission spectrometry for Be, Cd, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn. Questionnaires were administered to a participant from each sampling unit to determine drinking water consumption related information and demographics. Exposure and risks were estimated for each individual by direct calculation, and for Izmir population by Monte Carlo simulation. Six trace metals (As, Cr, Cu, Mn, Ni, and Zn) were detected in >50% of the samples. Concentrations of As and Ni exceeded the corresponding standards in 20% and 58% of the samples, respectively. As a result, arsenic noncarcinogenic risks were higher than the level of concern for 19% of the population, whereas carcinogenic risks were >10(-4) for 46%, and >10(-6) for 90% of the population.     

Neurobehavioral effects of exposure to trichloroethylene through a municipal water supply

We studied a population-based sample of 143 residents of a community in which the municipal water supply had been contaminated with trichloroethylene (TCE) and related chemicals from several adjacent hazardous waste sites between 1981 and 1986. A hydraulic simulation model was used in conjunction with a geographic information system (GIS) to estimate residential water supply exposures to TCE; 80% of the participants had potential TCE exposure exceeding the maximum contaminant level (5 ppb). The Neurobehavioral Core Test Battery (NCTB), tests of visual contrast sensitivity, and the profile of mood states (POMS) were administered approximately 6 years following peak concentrations of TCE in municipal drinking water. Multivariate analysis of variance adjusted for potential confounders was used to compare mean test scores of residents classified by estimated TCE exposure (< or =5, >5-10, >10-15, >15 ppb). TCE exposure >15 ppb was associated with poorer performance on the digit symbol, contrast sensitivity C test, and contrast sensitivity D test and higher mean scores for confusion, depression, and tension. We found evidence of a strong interaction between exposure to TCE and alcohol consumption; the associations for the NCTB and POMS among persons in the high-exposure group who also consumed alcohol were stronger and were statistically significant for the Benton, digit symbol, digit span, and simple reaction time tests, as well as for confusion, depression, and tension. This study adds to the evidence that long-term exposure to low concentrations of TCE is associated with neurobehavioral deficits and demonstrates the usefulness of GIS-based modeling in exposure assessment.     

Development of a health-protective drinking water level for perchlorate

We evaluated animal and human toxicity data for perchlorate and identified reduction of thyroidal iodide uptake as the critical end point in the development of a health-protective drinking water level [also known as the public health goal (PHG)] for the chemical. This work was performed under the drinking water program of the Office of Environmental Health Hazard Assessment of the California Environmental Protection Agency. For dose-response characterization, we applied benchmark-dose modeling to human data and determined a point of departure (the 95% lower confidence limit for 5% inhibition of iodide uptake) of 0.0037 mg/kg/day. A PHG of 6 ppb was calculated by using an uncertainty factor of 10, a relative source contribution of 60%, and exposure assumptions specific to pregnant women. The California Department of Health Services will use the PHG, together with other considerations such as economic impact and engineering feasibility, to develop a California maximum contaminant level for perchlorate. We consider the PHG to be adequately protective of sensitive subpopulations, including pregnant women, their fetuses, infants, and people with hypothyroidism.     

Prevalence of thyroid diseases in Nevada counties with respect to perchlorate in drinking water

Perchlorate is well-known to inhibit the uptake of iodine by the thyroid and has been shown to do so at doses in the milligrams-per-day range and higher. Perchlorate has been found in the water supply of Clark County (Las Vegas), Nevada, at 4 to 24 micrograms/L (parts per billion) and may provide exposure dosages in the tens of micrograms per day. An analysis of the Medicaid database from Nevada was undertaken to determine whether an increase in the prevalence of any thyroid disease was associated with that level of perchlorate content. The prevalence of persons being seen for thyroid disease or for specific thyroid diseases (goiter, nodule, thyrotoxicosis, congenital hypothyroidism, acquired hypothyroidism, thyroiditis, and other thyroid disorders) and for thyroid cancer among the Medicaid-eligible population of each county was calculated for the 2-year period 1997 to 1998. The prevalences in Clark County were compared with those in Washoe County (i.e., Reno), the second most populous county in the state, and with those for the rest of the state. There was no evidence of an increased rate of thyroid disease (or of any specific thyroid disease) associated with perchlorate exposure. Generally, the prevalences in the metropolitan parts of the state were lower than for the rest of the state, particularly for acquired hypothyroidism. This analysis found no evidence that perchlorate-containing drinking water at the given level increased the prevalence of acquired hypothyroidism or of any other thyroid condition.