Widespread disinfectant by-products (DBPs) trihalomethanes (THMs) in drinking water have been consistently associated with bladder cancer. This study reports on data on mean THM levels in municipal drinking water in 28 European countries.
The exposure-response function for average THM levels and bladder cancer were analysed, based on recent pooled epidemiological data and meta-analysis from studies on the relationship between THM exposure and bladder cancer. The odds ratios for bladder cancer associated with mean THM levels (relative to no exposure), population-attributable fraction (PAF) and number of attributable bladder cancer cases were estimated in different scenarios using incidence rates from the Global Burden of Disease Study 2016.
The estimated population-weighted mean THM level was 11.7 μ g /L. The estimated bladder cancer PAF was 4.9% (95% CI 2.5-7.1), accounting for 6,561 (95% CI 3,389-9,537) bladder cancer cases per year.
An odds ratio (OR) of 1.004 (95% CI 1.002-1.006) for a 1μg/L increase in THM, was derived.
If the current EU THM mean was not exceeded, 2,868 (95% CI 1,522-4,060) annual attributable bladder cancer cases could potentially be avoided.
The study concluded that current THM levels in certain countries could lead to a considerable burden of potentially avoidable bladder cancers.