Pesticides and prostate cancer incidence and mortality: An environment-wide association study.

Background: Prostate cancer is the most common cancer among men in the United States, yet modifiable risk factors remain elusive. In this study, the authors investigated the potential role of agricultural pesticide exposure in prostate cancer incidence and mortality.

Methods: For this environment-wide association study (EWAS), linear regression was used to analyze county-level associations between the annual use of 295 distinct pesticides (measured in kg per county) and prostate cancer incidence and mortality rates in the contiguous United States. Data were analyzed in two cohorts: 1997-2001 pesticide use with 2011-2015 outcomes (discovery) and 2002-2006 use with 2016-2020 outcomes (replication). The reported effect sizes highlight how a 1-standard-deviation increase in log-transformed pesticide use (kg per county) corresponds to changes in incidence. Analyses were adjusted for county-level demographics, agricultural data, and multiple testing.

Results: Twenty-two pesticides showed consistent, direct associations with prostate cancer incidence across both cohorts. Of these, four pesticides were also associated with prostate cancer mortality. In the replication cohort, each 1-standard-deviation increase in log-transformed pesticide use corresponded to incidence increases per 100,000 individuals (trifluralin, 6.56 [95% confidence interval (CI), 5.04-8.07]; cloransulam-methyl, 6.18 [95% CI, 4.06-8.31]; diflufenzopyr, 3.20 [95% CI, 1.09-5.31]; and thiamethoxam, 2.82 [95% CI, 1.14-4.50]). Limitations included ecological study design, potential unmeasured confounding, and lack of individual-level exposure data.

Conclusions: The results of this study suggest a potential link between certain pesticides and increased prostate cancer incidence and mortality. These findings warrant further investigation of these specific pesticides to confirm their role in prostate cancer risk and to develop potential public health interventions.