Lifetime exposure to arsenic in drinking water and bladder cancer: a population-based case-control study in Michigan, USA

Abstract

Objective: Arsenic in drinking water has been linked with the risk of urinary bladder cancer, but the dose-response relationships for arsenic exposures below 100 microg/L remain equivocal. We conducted a population-based case-control study in southeastern Michigan, USA, where approximately 230,000 people were exposed to arsenic concentrations between 10 and 100 microg/L.

Methods: This study included 411 bladder cancer cases diagnosed between 2000 and 2004, and 566 controls recruited during the same period. Individual lifetime exposure profiles were reconstructed, and residential water source histories, water consumption practices, and water arsenic measurements or modeled estimates were determined at all residences. Arsenic exposure was estimated for 99% of participants' person-years.

Results: Overall, an increase in bladder cancer risk was not found for time-weighted average lifetime arsenic exposure >10 microg/L when compared with a reference group exposed to <1 microg/L (odds ratio (OR) = 1.10; 95% confidence interval (CI): 0.65, 1.86). Among ever-smokers, risks from arsenic exposure >10 microg/L were similarly not elevated when compared to the reference group (OR = 0.94; 95% CI: 0.50, 1.78).

Conclusions: We did not find persuasive evidence of an association between low-level arsenic exposure and bladder cancer. Selecting the appropriate exposure metric needs to be thoughtfully considered when investigating risk from low-level arsenic exposure.

Fig. 1

Arsenic concentrations in drinking water at current residence of cases and controls in eleven county study area of Southeastern Michigan, Enrolled 2002–2006

Fig. 2

Multivariate-adjusted odds ratios and 95% confidence intervals for arsenic in drinking water and bladder cancer, among those who consume >1 L/day of water from home, by age of exposure; Southeastern Michigan, Enrolled 2002–2006. Adjusted for cigarette smoking history, education, history of employment in high-risk occupation, family history of bladder cancer, age, race, and sex. Exposure >10 µg/L between ages 45 and 52 significantly associated with bladder cancer