Objective: The objective of this analysis was to evaluate relationships between urinary arsenic concentrations and estimated arsenic consumption from water among United States (U.S.) Hispanic, U.S. non-Hispanic, and Mexican participants from the Binational Arsenic Exposure Survey (BAsES). The impact of water consumption reporting on estimated arsenic exposures is evaluated.

Introduction: Arsenic is naturally occurring in the environment and is recognized as a human skin, lung and bladder carcinogen and has been associated with other solid tumors following chronic ingestion or inhalation. Elevated levels of arsenic are found in groundwater reserves of Arizona and northern Mexico. It is believed that drinking water is a significant contributor to arsenic exposure. However, little is known about water consumption volumes among U.S. Hispanic and non-Hispanics, and Mexicans. Modeling the relationship between water-based exposures relies on accurate selfreporting of consumption.

Methods: Over 350 households (152 in Arizona, 225 in Sonora) were recruited. All adults over age 18 were asked to participate and provide a first-morning urine sample. Total water volume consumed was reported by 24-hour diet recall. Water samples were collected from all household water sources, including tap (filtered and unfiltered) and bottled water. Arsenic in urine and water was measured using ICP-MS through a central laboratory.

Results: Daily water consumption varied between ethnic groups. Among U.S. Hispanics, median 24-hour water volume consumed was 1.16 L and 1.49 L for U.S. non-Hispanics. Median reported daily water intake was only 0.27 L for Sonoran participants. Using these self-reported intake volumes, estimated median arsenic exposure from water was 3.28 µg/day (Inter-quartile range = 1.77 – 7.64) for U.S. Hispanics, 5.01 µg/day (IQR = 2.16 – 15.24) for U.S. non-Hispanics, and 1.22 µg/day (IQR = 0.27 – 3.34) for Sonoran participants. In contrast to these estimated exposures, median urinary total arsenic was 22.88 µg/L (IQR = 12.28 – 32.81) for U.S. Hispanics, 22.35 µg/L (IQR = 14.64 – 43.23) for U.S. non-Hispanics and 59.01 µg/L (IQR= 32.46 – 97.34) for Sonoran participants.

Discussion: Urinary arsenic excretion was significantly higher for Mexican participants than for U.S. participants, although estimated arsenic exposure based on water consumption was lower. Part of the difference could be due to lower than expected water consumption in Mexico. Lower water volumes could be attributed to Mexicans drinking less water or under-reporting water intake on the 24-hour diet recall. The impact of other dietary factors needs to also be considered.

Second AACR International Conference on the Science of Cancer Health Disparities— Feb 3–6, 2009; Carefree, AZ