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APHA Scientific Session and Event Listing

Recorded presentation

Melissa Slotnick, MPH, MESc, Jaymie Meliker, PhD, and Jerome Nriagu, PhD. Environmental Health Sciences, The University of Michigan School of Public Health, 109 Observatory, Ann Arbor, MI 48109, 734-647-5833, slotnick@umich.edu

Arsenic concentrations in Southeastern Michigan groundwater frequently exceed the U.S. Environmental Protection Agency's maximum contaminant level (MCL) of 10 µg/L. Concentrations are highest in private wells, which are typically not monitored on a routine basis. Therefore, understanding the effect of temporal variability and in-home point-of-use (POU) treatment devices on concentrations becomes increasingly important. Furthering knowledge of these issues can lead to better characterization of populations at risk for exceeding the MCL while improving exposure assessment for environmental health 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=215), public water supplies (n=33), and bottled water (n=13); mean arsenic concentration was highest in private wells (7.42 µg/L) and lowest in bottled water samples (0.28 µg/L). Arsenic concentrations in drinking water samples were highly correlated (r=0.88, p<0.0001, n=196), with 3% of the population exceeding the 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. These results indicate that while a single residential arsenic measurement may be used to represent exposure in this region, researchers should obtain information on changes in water source and POU treatment devices to better characterize population exposures over time.

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