Long-Term Exposure to Nitrate and Trihalomethanes in Drinking Water and Prostate Cancer: A Multicase–Control Study in Spain (MCC-Spain)
Menée en Espagne sur la période 2008-2013 auprès de 927 témoins et 697 patients atteints d'un cancer de la prostate, cette étude analyse l'association entre une ingestion de nitrates et de trihalométhanes contenus dans l'eau de boisson et le risque de développer la maladie
BACKGROUND: Nitrate and trihalomethanes (THMs) in drinking water are widespread and are potential human carcinogens. OBJECTIVE: 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 controlswere recruited in Spain, providing information on residential histories and type of water consumed. Average nitrate and THMs levels in drinkingwater 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, anddietary 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. <5:5mg=dwas associated with an OR of 1.74 (95% CI: 1.19, 2.54) overall, and 2.78 (95% CI: 1.23, 6.27) for tumors with Gleason scores≥8. Associations were higherin the youngest and those with lower intakes offiber, fruit/vegetables, and vitamin C. Waterborne ingested THMs were not associated with prostate cancer.Residential tap water levels of Br-THMs and chloroform showed, respectively, inverse and positive associations with prostate cancer. CONCLUSIONS: Findings suggest long-term waterborne ingested nitrate could be a risk factor of prostate cancer, particularly for aggressive tumors.High intakes offiber, fruit/vegetables and vitamin C may lower this risk. Association with residential levels but not ingested chloroform/Br-THMmay suggest inhalation and dermal routes could be relevant for prostate cancer.