Urinary Arsenic Species in Relation to Drinking Water and Toenails in a US Population

Abstract

ISEE-315 Objective: Chronic exposure of humans to inorganic arsenic has been associated with increase risk of cancer, skin, and cardiovascular disorders, among others. Key diagnostic laboratory tests for arsenic exposure are toenails and urinary arsenic. The objectives of this study are to identify the determinants of arsenic in urine and toenails and to evaluate methods of quantifying individual exposures to arsenic at low levels. Material and Methods: A subsample of 100 individuals was selected from a bladder cancer case-control study of Southeastern Michigan residents where arsenic in drinking water has been studied. Through summer and fall of 2006, urine, toenails, and water samples were collected during a series of home-interviews. Total measurements of arsenic in water and toenails were analyzed using ICP-MS. Urine arsenic species were determined using HPLC-ICPMS. Results: Tap water arsenic concentrations ranged from 0.003 to 42.2 μg/L. Only 4 observations were below or equal to 1 μg/L. The mean of arsenic in water, urine, and toenails were 4.1, 20.0, and 0.11 μg/L, respectively. Among the 100 individuals, a correlation (r) was detected between urine and water [0.303 (P = 0.0029)] whereas a stronger correlation was detected between urine and toenails [0.364 (P = 0.0004)]. Multiple comparison analysis between groups of different arsenic concentrations in water and urinary arsenic showed statistical significant results between all groups (P < 0.0001). Likewise, data stratification by water source concentrations shows a significant correlation between urine and toenails [r = 0.453 (P = 0.0063)] in well water. Conclusions: Urine and toenails are useful tools to measure arsenic exposure. These biomarkers may more accurately reflect the total dose of exposure in populations exposed to low but potentially carcinogenic levels of drinking water arsenic.