Living in areas with high agricultural pesticide exposure is associated with higher cancer risks, according to a new study.
Pesticides, widely present in food, water, and the environment, may be linked to an increased cancer risk, particularly among more socially vulnerable populations, new research has found.
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The study, published in the journal Nature Health, found a strong association between exposure to agricultural pesticides and the risk of developing cancer, by analysing environmental data, cancer registries, and biological samples in Peru.
“This is the first time we have been able to link pesticide exposure, on a national scale, to biological changes suggesting an increased risk of cancer,” explained Stéphane Bertani, a researcher in molecular biology at the French National Research Institute for Sustainable Development (IRD).
The authors noted that the real-world carcinogenicity of pesticides remains insufficiently understood, which hinders rigorous risk assessments and delays effective public health interventions.
Aiming to close this gap, the researchers identified areas in Peru where people were both more likely to be exposed to pesticides and more likely to be affected by certain cancers, and found that the risk of developing cancer in these zones was 150 percent higher.
The study was conducted in collaboration between the French National Research Institute for Development in Peru, the Institut Pasteur, the University of Toulouse, and Peru’s National Institute of Neoplastic Diseases.
The team modelled pesticide dispersion in the environment over six years, from 2014 to 2019, creating a high-resolution map of areas with the greatest exposure risk, according to Jorge Honles, an epidemiologist at the University of Toulouse.
Zones of moderate and high risk covered more than one-third of the national territory, with off-site contamination extending up to 30 to 50 kilometres beyond cultivated land, driven by long-range transport.
The researchers applied the model across the country, incorporating agricultural chemicals – none of which are classified as known human carcinogens by the World Health Organization (WHO) – alongside models tracking their environmental dispersal.
Cross-referencing the pesticide mapping with cancer registries, the study drew on data from more than 150,000 patients diagnosed between 2007 and 2020.
The highest environmental pesticide exposure risks were concentrated in the Andean highlands and slopes, especially in areas where scarce precipitation can exacerbate pesticide accumulation.
Molecular analyses showed that pesticides disrupt processes that help maintain cell function and cellular identity. These changes can appear before cancer develops, suggesting early, cumulative, and silent effects that may make tissues more vulnerable to other risk factors, such as infections, inflammation, or environmental stressors, the study noted.
Are pesticides linked to all types of cancer?
The study shows that certain tumours, though affecting different organs, share common biological vulnerabilities linked to their cellular origin that pesticide exposure may weaken.
The most extensive at-risk zones were associated with endodermal and ectodermal epithelial cancers, the most common type among adults, affecting mainly the gastrointestinal tract, lungs, and skin.
In Peru, hepatocellular carcinoma (HCC), the most prevalent liver cancer subtype, disproportionately affects young, non-cirrhotic individuals with Indigenous ancestry, particularly in central regions such as Junín, the researchers noted.
The liver is a key organ in the metabolism of chemicals and is considered a sentinel site for environmental exposure, the authors noted.
While this pattern has previously been linked to occult hepatitis B infection, the study found that liver cancer clusters coincided with areas of heavy pesticide exposure, and that non-tumour liver tissue carried a molecular signature consistent with early carcinogen exposure.
Pesticides are widespread in food, water, and ecosystems, meaning mapping environmental exposure is considerably challenging, the authors wrote.
In regions where intensive agriculture, unsustainable land management, and limited healthcare converge, pesticide dispersal can erode ecological resilience and deepen long-standing health inequalities.
The researchers said these findings underscore the need to embed socio-ecological equity within regulatory policy, “an essential step towards mitigating ecological harm and protecting vulnerable populations from environmentally driven cancers”.
