Pesticides are critical to agricultural intensification but can negatively impact human health. We show that as soy cultivation spread across Brazil, agricultural pesticide exposure was associated with increased childhood cancer mortality among the broader population indirectly exposed to these chemicals. We find that populations were exposed to pesticides through the water supply, but negative health effects were mitigated by access to high-quality cancer treatment centers. Our results support policies to strengthen pesticide regulation, especially in contexts intensifying their food production systems, and increased public health attention to pesticide exposure in the broader community.

Over the last several decades, Brazil has become both the world’s leading soy producer and the world’s leading consumer of hazardous pesticides. Despite identified links between pesticide exposure and carcinogenesis, there has been little population-level research on the effects of pesticide intensification on broader human health in Brazil. We estimate the relationship between expanded soy production—and related community exposure to pesticides—on childhood cancer incidence using 15 y of data on disease mortality. We find a statistically significant increase in pediatric leukemia following expanded local soy production, but timely access to treatment mitigates this relationship. We show that pesticide exposure likely occurs via water supply penetration. Our findings represent only the tip of the iceberg for substantial health externalities of high-input crop production and land use change. Our results are of particular interest in developing contexts with demand for intensified food production systems and underscore the need for stronger regulation of pesticides and increased public health attention to exposure in the broader community.