#105-S estimating residential exposure to drinking water arsenic in inner mongolia, china for epidemiologic studies

Abstract PURPOSE: In the Ba Men region of Inner Mongolia, China, a high prevalence of chronic arsenism has been reported in earlier studies. A survey of the water supply system was conducted between 1991-1998 to better characterize the arsenic (As) concentrations in the drinking water supply of local villages. METHODS: A total of 14,866 wells were analyzed for As content. Colorimetry based on silver diethyldithiocarbamate, an adaptation of the mercury bromide stain technique, and atomic absorption spectroscopy were used to determine the As content of the water supply. Methods used to assign individual level exposure information based on aggregate exposure data, their advantages and disadvantages, will be discussed. RESULTS: As concentrations ranged from below the limit of detection to 1.2 mg/l. Elevated concentrations were related to well depth (maximum at the 15 to 25 meter (m) category), well type (most high concentrations associated with the small household pump wells) and the date the well was built (peaks from 1980–1990). Over 43,600 persons consumed water with As concentrations above 0.01 mg/l (14,500 above 0.05 mg/l, 480 above 0.5 mg/l). There were significant differences between different counties and villages within each county. CONCLUSION: The presented database of As in wells of the Ba Men region provides a useful tool for planning future water explorations when combined with geological information. It also helps in the design of upcoming epidemiological studies on the effects of arsenic in drinking water.