A study published in *Nature Health* reports a statistical link between environmental exposure to mixtures of agricultural pesticides and higher cancer risk in Peru. Using modeled pesticide dispersion from 2014 to 2019 and cancer registry data from 2007 to 2020 covering more than 150,000 cases, researchers found that people living in high-exposure areas faced, on average, about a 150% higher likelihood of cancer, with Indigenous and rural farming communities among those most exposed.
Scientists affiliated with the French National Research Institute for Sustainable Development (IRD), Institut Pasteur, the University of Toulouse and Peru’s National Institute of Neoplastic Diseases (INEN) used high-resolution environmental modeling to estimate how widely used agricultural pesticides disperse and persist across Peru.
The analysis modeled the environmental fate of 31 commonly used pesticides over a six-year period (2014–2019), producing a national exposure map intended to capture the real-world effects of pesticide mixtures rather than single chemicals.
“We first modeled the dispersion of pesticides in the environment over a six-year period, from 2014 to 2019, which allowed us to create a high-resolution map and identify areas with the highest risk of exposure,” said Jorge Honles, an epidemiologist at the University of Toulouse.
The study then compared the modeled exposure patterns with cancer cases recorded in INEN’s registry from 2007 to 2020, a dataset described by the researchers as the country’s most comprehensive cancer record system. The researchers reported that districts with higher modeled pesticide exposure also showed higher rates of certain cancers. On average, they found the likelihood of developing cancer was about 150% greater in the highest-exposure areas.
The researchers also reported that exposure was unevenly distributed: Indigenous and rural farming communities were among those facing the highest environmental concentrations. According to the research summary released by Institut Pasteur, individuals in these groups were exposed to around 12 pesticides simultaneously at elevated concentrations.
Although none of the modeled pesticides were classified as Group 1 (“carcinogenic to humans”) by the International Agency for Research on Cancer, the researchers argued that conventional safety frameworks may miss risks that emerge when multiple chemicals coexist in the environment.
“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,” said Stéphane Bertani, a molecular biologist at IRD.
To explore potential biological mechanisms, the study drew on molecular analyses that, according to the Institut Pasteur summary, were led by Pascal Pineau and focused on how pesticide mixtures could interfere with cellular functions, particularly in the liver—an organ central to processing many chemicals.
The researchers said the findings support calls to update chemical risk assessment and public-health policy to better account for mixture exposures and real-world conditions, including climate variability that can influence how pesticides move through the environment.
