Bladder Cancer Burden from Exposure to Trihalomethanes in Drinking Water in the European Union

Abstract

BACKGROUND and AIM: Trihalomethanes (THMs) are prevalent chemicals in drinking water (DW). Exposure is through ingestion, inhalation and dermal absorption and has consistently been associated with increased bladder cancer (BC) risk. We assessed THMs levels in DW and estimated the burden of bladder cancer in the European Union (EU). METHODS: We obtained annual mean THM levels in municipal DW in the 28 EU countries in 2010-2017 through a standardized questionnaire and calculated the population-weighted EU mean. We used published THM levels in countries where THM data was not provided for further imputations. We estimated the attributable BC cases following the burden of disease approach. The dose-response function was obtained from the largest international pooled-analysis on THM exposure and BC and was used to estimate the odds ratio for each country, with an alternative exposure scenario of <5µg/L. We calculated the country annual number of attributable BC cases using incidence rates from GLOBOCAN. RESULTS: The amount of data, representativeness and accuracy was heterogeneous among countries. Mean THM level in drinking water in EU-28 was 11.9µg/L (SD 11.1), ranging from 0.0µg/L (Denmark) to 66.2µg/L (Cyprus). The EU 28 average population attributable fraction was 4.6%, and the maximum was 24% in Romania (95%CI 13-34) and 23% in Cyprus (95%CI 12-33). In total, 5,708 (95%CI 2,940-8,318) annual BC cases were attributable to THM exposure in the EU (ranging from 0 in Denmark to 1,498 in Spain). If THM levels in DW were reduced to the EU mean of 11.9 µg/L among countries above this level, 2,438 (95%CI 1,287-3,469) cases of BC could be avoided annually in the EU. CONCLUSIONS: Although the country mean THM levels were below the legal limit (100μg/L), the attributable BC burden and related costs are considerable and can be further lowered by improvements in the quality of DW, especially in countries with higher THM levels.Funding: FP7 EXPOsOMICS Project and CIBERESP.