Prenatal Exposure to Pesticides Linked to Childhood Brain Tumors

Exposure during pregnancy to a wide variety of pesticides may be associated with the development of childhood brain tumors, according to new findings published in Environmental Research.

“Many pesticides are neurotoxicants, and have even been found in cord blood, indicating placental transfer of these toxins to the developing fetus,” said co-author Shiraya Thompson, of the University of California, Los Angeles Fielding School of Public Health (FSPH), in a press release. “This, in turn, suggests prenatal pesticide exposure may increase childhood brain cancer risk.”

For this study, investigators utilized the California Cancer Registry to match children aged less than 6 years with cancer with age-matched controls without cancer. After restricting analysis to children born between 1998 and 2011 who lived in rural areas, the final total was 667 patients with childhood central nervous system (CNS) tumors and 123,158 controls. Prenatal exposure was measured according to pesticide reporting from the California Department of Pesticide Regulation’s Pesticide Use Reporting system. Exposure was defined as pesticides applied with 4,000 meters from the maternal residence at birth.

Exposure to certain pesticides were found to increase the odds ratio (OR) of diffuse astrocytoma, including bromacil (OR 2.12; 95% confidence interval [CI] 1.13-3.97), thiophanate-methyl (OR 1.64; 95% CI 1.02-2.66), triforine (OR 2.38; 95% CI 1.44-3.92), and kresoxim methyl (OR 2.09; 95% CI 1.03-4.21). Risk of medulloblastoma was increased with exposure to chlorothalonil (OR 1.78; 95% CI 1.15-2.76), propiconazole (OR 1.60; 95% CI 1.02-2.53), dimethoate (OR 1.60; 95% CI 1.06-2.43), and linuron (OR 2.52; 95% CI 1.25-5.11). Ependymoma risk was increased with exposure to thiophanate-methyl (OR 1.72; 95% CI 1.10-2.68).

“Exposure to certain pesticides, simply through residential proximity to agricultural applications during pregnancy, may increase the risk of childhood central nervous system tumors,” said Dr. Beate Ritz, MD, PhD, professor at FSPH. “Policy interventions to reduce pesticide exposure in individuals residing near agricultural fields should be considered to protect the health of children.”