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NEVADA ARSENIC STUDY
Impact/Purpose:
The aims of the overall study are to (1) describe exposure of a population using biomarkers, (2) assess and characterize the biological effects of arsenic in humans, (3) assess arsenic exposure and link exposure information to the results of health effects measures, and (4) link the study results from Nevada with ongoing studies conducted in the Inner Mongolia population in China. The first phase of this project as described below will determine the feasibility of conducting further studies in this region to examine the relationship between arsenic exposure and certain health conditions.
Description:
The effects of exposure to arsenic in U.S. drinking water at low levels are difficult to assess. In particular, studies of sufficient sample size on US populations exposed to arsenic in drinking water are few. Churchill County, NV (population 25000) has arsenic levels in drinking water supplies that range from more than 500 ppb down to the limit of detection (less than two ppb). The largest community and county seat is Fallon, NV (population 5000). The Fallon community water supply currently and historically has arsenic levels of 100 ppb. A few studies on small numbers of individuals (35) have been conducted in the Fallon area and were inconclusive as to whether the population was experiencing any effects associated with chronic exposures to arsenic. The Churchill County population represents perhaps the largest U.S. population in a single geographic area exposed to arsenic levels higher than the current drinking water standard of 10 :g/l. Recent EPA research in both Utah and Inner Mongolia, China suggests that because biomarkers represent events along the path to disease, such indicators may therefore be able to provide enough sensitivity to conduct a study of the effects of chronic arsenic exposure from drinking water. Biomarker assays are conducted on biological specimens such as blood or urine. We conducted an arsenic biomarker study and large scale screening of 905 people from Churchill County, Nevada. We evaluated exposure biomarkers and arsenic metabolic profiles. Participants were screened for three potential health effects (diabetes, hypertension and loss of olfactory senses). We collected information to analyze environmental pathways of exposure through the collection of drinking water samples and biological samples (blood, toe nails, buccal cells and urine). The following information was obtained from the subjects: height and weight, a self administered 10- minute questionnaire, a self administered five- minute test on olfactory sensitivity, resting, sitting and standing blood pressure, heart rate and pulse oximetry, a spot urine and a blood specimen. The next morning all subjects provided a first-morning void urine sample and a water specimen from their home tap. Water samples were analyzed for arsenic. All urine samples will be analyzed for inorganic arsenic species, arsenic metabolites, organic arsenic species, cotinine, and creatinine. Blood samples were analyzed for glycogen and methyltransferase. A smaller number of individuals had their their blood tested for a bank of biomarkers related to oxidative stress and DNA damage. In addition, global positioning information on each subject's residence was acquired to conduct spatial analysis in relation to arsenic concentration for those subjects on a private well and location in the community's drinking water distribution system.