Long-term exposure to nitrate and trihalomethanes in drinking water and prostate cancer: a multicase-control study in Spain (MCC-Spain)

Background: Nitrate and trihalomethanes (THMs) in drinking water are widespread and are potential human carcinogens. Objetive: We evaluated the association between drinking-water exposure to nitrate and THMs and prostate cancer. Methods: During the period 2008–2013, 697 hospital-based incident prostate cancer cases (97 aggressive tumors) and 927 population-based controls were recruited in Spain, providing information on residential histories and type of water consumed. Average nitrate and THMs levels in drinking water were linked with lifetime water consumption to calculate waterborne ingestion. Odds ratios (OR) and 95% confidence intervals (CI) were esti mated using mixed models with recruitment area as random effect. Effect modification by tumor grade (Gleason score), age, education, lifestyle, and dietary factors was explored. Results: Mean ( ± standard deviation) adult lifetime waterborne ingested nitrate (milligrams per day), brominated (Br)-THMs (micrograms per day), and chloroform (micrograms per day) were 11.5 ( ± 9:0), 20.7 ( ± 32:4), and 15.1 ( ± 14:7) in controls. Waterborne ingested nitrate >13:8 vs.