Abstract
BACKGROUND: Epidemiologic evidence demonstrates increased lung, bladder, and skin cancer risk among individuals exposed to arsenic in drinking water. Some studies report associations with prostate cancer, but data are limited. This study aimed to examine the association between arsenic in drinking water and prostate cancer in Northern Chile. With its wide range of exposure (<10-860 µg/L), large population, and accurate information on historic exposures, Northern Chile is the best place to investigate the human carcinogenic effects of arsenic. METHODS: A case-control study conducted from 2015 to 2019 enrolled 343 prostate cancer cases and 337 age-matched controls among men ages ≥40 years. Cases were ascertained from cancer committees, hospitals, and medical facilities in the area. Controls were ascertained from the Chile Voter Registry, including >90% of adults ages >50 years. Information on lifetime arsenic exposure and potential confounders such as smoking, family history, and prostate cancer screening were collected. RESULTS: Twenty-three percent of participants were exposed to arsenic concentrations >800 µg/L in their lifetime (80× recommended thresholds). Cases and controls were demographically similar. After adjustment for age and smoking status, participants with the highest quartile of lifetime cumulative and average arsenic concentrations in drinking water each had 1.14 (95% confidence interval, 0.71-1.84) and 1.17 (95% confidence interval, 0.73-1.89) times the odds of prostate cancer compared with participants with the lowest quartile of exposure, respectively. CONCLUSIONS: Arsenic exposure in drinking water, even at high levels, was not associated with increased risk of prostate cancer. IMPACT: Our findings suggest that arsenic is not a risk factor for prostate cancer.