Living in areas with high environmental pesticide exposure may increase cancer risk. Digest
Scientists have long suspected that pesticides may contribute to cancer risk, but most safety studies examine one chemical at a time rather than the mixtures people are actually exposed to in everyday life. A new study addressed this gap by analyzing whether real-world pesticide exposure is linked to patterns of cancer across a population.
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The researchers estimated environmental pesticide exposure risk for 31 commonly used pesticides across Peru from 2014 to 2019 by dividing the country into small 100-by-100-meter areas and calculating an exposure risk score based on where pesticides are used, along with environmental data like rainfall, soil conditions, and how pesticides spread, break down, and build up in the environment. They combined these into a national map of long-term cumulative pesticide exposure risk, then compared it with 158,072 cancer cases.
- The analysis identified 436 areas where cancer rates were both higher than expected for the general population and associated with higher estimated pesticide exposure. Cancer rates ranged from 14% above expected up to about 9 times higher, with an overall increase of about 2.5 times.
- Measurements from hair samples in 50 residents matched the exposure map, suggesting the model reflects real-world exposure patterns.
- The most extensive at-risk zones were associated with epithelial cancers affecting the gastrointestinal tract, lungs, and skin, followed by cancers of the female genital organs and kidney.
- In liver samples from 36 cancer patients in high-exposure hotspot areas, the researchers found a distinct pattern of gene activity associated with non-genotoxic carcinogens, substances that promote cancer by disrupting cell function rather than directly damaging DNA.
- The same liver samples also showed altered activity in master transcription factors, proteins that control large networks of genes. When this control is disrupted, cells can lose their normal identity and shift toward abnormal states that can lead to cancer.
Together, these findings suggest that long-term environmental exposure to pesticide mixtures may disrupt the regulatory systems that keep cells stable. These disruptions may push cells into an unstable, pre-cancer state, making them more vulnerable to additional triggers, such as other environmental pollutants, infections, and unhealthy lifestyle factors, that can drive the final step toward cancer.
Because the study was observational and relied mostly on modeled rather than directly measured pesticide exposure, it cannot establish a causal link between pesticides and cancer risk. Even so, the results point to the need for more cautious pesticide use and better strategies to protect communities facing the highest exposure levels. In this clip, I discuss a recent study suggesting that living near a golf course may increase the risk of Parkinson's disease due to pesticide exposure.