Exposure to the herbicide 2,4-dichlorophenoxyacetic acid and prostate cancer among U.S. adult men.

Purpose: Prostate cancer is the second most diagnosed male malignancy in the U.S. 2,4-Dichlorophenoxyacetic acid (2,4-D) is a commonly used herbicide and potential carcinogen. The researchers evaluated the association between prostate cancer and 2,4-D.

Methods: Data was leveraged from the National Health and Nutrition Examination Survey (NHANES), a population-based, cross-sectional study of men and women in the U.S. Our cohort of interest was men aged 50 years and over. Urinary 2,4-D served as the measure of exposure. Our primary outcome was history of prostate cancer based on an individual's reply of "yes" to either ever having been diagnosed with prostate cancer and/or having received treatment for prostate cancer. Chi-square, one-way analysis of variance (ANOVA), and multivariable, weighted logistic regression were used to analyze the relationship between 2,4-D and prostate cancer.

Results: We identified 1,788 eligible men, representing an estimated 691,709 men after survey weighting. The median 2,4-D level was 0.28 µg/L (IQR: 0.26-0.53), and the geometric mean was 0.38 µg/L. Increasing exposure of 2,4-D was associated with prostate cancer (OR 1.72, 95% CI [1.2,2.4]). Individuals in the highest quartile of 2,4-D exposure had a higher odds of a prostate cancer diagnosis compared to the lowest quartile (OR = 3.46 95% CI [1.11,10.72]). Age stratification revealed statistically significant associations between 2,4-D and prostate cancer in men age 70 + who were in the highest quartile of exposure (OR = 3.79 95% CI [1.51,9.52]).

Conclusions: These findings implicate 2,4-D exposure in the risk of prostate cancer. Future studies are warranted to corroborate these findings and elucidate potential mechanisms underlying these associations.