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

Abstract

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=0.16] and brominated THMs [OR=1.98 (95% CI: 1.19, 3.29), p-trend=0.03]. For cumulative intake mg, the OR at the 95th percentile of total THMs was 1.45 (95% CI: 0.95, 2.2), p-trend=0.13; the ORs at the 95th percentile for chlorinated and brominated THMs were 1.77 (95% CI: 1.05, 2,.99), p-trend=0.07 and 1.78 (95% CI: 1.05, 3.00), p-trend=0.02, respectively. The OR in the highest category of showering/bathing for brominated THMs was 1.43 (95% CI: 0.80, 2.42), p-trend=0.10. We found no evidence of an association for bladder cancer and hours of swimming pool use.Conclusions:We observed a modest association between ingestion of water with higher THMs (>95th percentile vs.<25th percentile) and bladder cancer. Brominated THMs have been a particular concern based on toxicologic evidence, and our suggestive findings for multiple metrics require further study in a population with higher levels of these exposures. Data from this population do not support an association between swimming pool use and bladder cancer. https://doi.org/10.1289/EHP89

Trihalomethanes in Drinking Water and Bladder Cancer Burden in the European Union

“…We used pooled data for 3,481 cases and 5,977 controls from 7 case-control studies included in a meta-analysis by Costet et al (2011) to derive the continuous exposure-response function that was the basis of our country-specific ORs for bladder cancer in association with country-specific mean THM estimates. Although this is the most comprehensive pooled analysis currently available, it is limited to case-control studies and does not include a recent U.S. study of 1,213 bladder cancer cases and 1,418 controls (Beane Freeman et al 2017).…”

“…Our analyses are based on men and women combined. While most of the case-control studies included in the pooled analysis report a null or inverse association among women, there are also case-control studies showing higher risks in women than men (Beane Freeman et al 2017). Future studies may want to consider comparing estimates based on sex-specific exposure-response functions to estimates for men and women combined.…”

Prevention of bladder cancer incidence and recurrence

“…It has been suggested that the byproducts of water disinfection such as chlorinated and brominated trihalomethanes (THMs) may increase the risk of bladder cancer. This risk was evaluated in a recent population-based case-control study from the National Cancer Institute in the United States [33]. This showed a weak association between drinking water with high levels of THMs and bladder cancer (OR 1.53, 95%CI: 1.01-2.32).…”

Analysis of Cumulative Cancer Risk Associated with Disinfection Byproducts in United States Drinking Water

“…However, epidemiological research has reported associations between adverse health effects and the presence of disinfection byproducts in tap water at concentrations that generally meet applicable national drinking water standards [3]. Multiple studies have reported an increased risk of bladder cancer in association with exposure to drinking water disinfection byproducts [4][5][6], and the risk of other cancers has been suggested [7,8]. Birth defects [9] and miscarriages [10] have also been linked to disinfection byproducts.…”