Association between pesticide exposure and colorectal cancer risk: a systematic review and meta-analysis.

Colorectal cancer (CRC) is a leading global malignancy, yet the relationship between pesticide exposure and CRC risk remains controversial. This systematic review and meta-analysis evaluates the association between exposure to specific pesticide classes (fumigants, fungicides, herbicides, and insecticides) and the risk of colon, colorectal, and rectal cancers. A comprehensive search of international databases (Scopus, PubMed, Web of Science, Embase) was conducted up to January 2025. Adjusted risk estimates were pooled using a fixed-effect model for CRC outcomes. Analysis of 32 studies revealed no significant associations between fumigants and CRC risk [colon: ES = 0.87, 95% CI (0.57-1.17); colorectal: ES = 0.92, 95% CI (0.67-1.17); rectal: ES = 1.04, 95% CI (0.54-1.54)]. Similarly, fungicides showed no significant associations [colon: ES = 0.83, 95% CI (0.62-1.03); colorectal: ES = 0.89, 95% CI (0.72-1.07); rectal: ES = 0.96, 95% CI (0.62-1.31)]. Herbicides also demonstrated no risk associations across CRC [colon: ES = 0.98, 95% CI (0.85-1.10); colorectal: ES = 0.98, 95% CI (0.85-1.10); rectal: ES = 0.98, 95% CI (0.85-1.10)]. However, insecticide exposure was associated with a reduced risk of colon cancer (ES = 0.85, 95% CI: 0.80-0.91), though no significant links were observed for colorectal or rectal cancers. No association was observed between exposure to fumigants, fungicides, or herbicides and the risk of CRC. Insecticides may confer a modest protective effect against colon cancer, though further mechanistic and epidemiological studies are warranted.