Bladder Cancer and Water Disinfection By-product Exposures through Multiple Routes: A Population-Based Case–Control Study (New England, USA)

Background: Ingestion of disinfection byproducts has been associated with bladder cancer in multiple studies. Although associations with other routes of exposure have been suggested, epidemiologic evidence is limited. Objectives: We evaluated the relationship between bladder cancer and total, chlorinated, and brominated trihalomethanes (THMs) through various exposure routes. Methods: In a population-based case–control study in New England (n=1,213 cases; n=1,418 controls), we estimated lifetime exposure to THMs from ingestion, showering/bathing, and hours of swimming pool use. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) using unconditional logistic regression adjusted for confounders. Results: Adjusted ORs for bladder cancer comparing participants with exposure above the 95th percentile with those in the lowest quartile of exposure (based on the distribution in controls) were statistically significant for average daily intake mg/d of total THMs [OR=1.53 (95% CI: 1.01, 2.32), p-trend...