In Utero Pesticide Exposure and Leukemia in Brazilian Children <2 Years of Age

BACKGROUND: An association between pesticide exposure and cancer has been suggested. Infant leukemia is a rare neoplasm and its association with maternal pesticide exposure has been poorly explored. OBJECTIVES: We investigated the association between pesticide exposure during pregnancy and leukemia in children < 2 years of age. METHODS: A hospital-based case-control study was carried out in 13 Brazilian states during 1999-2007. Mothers of 252 cases and those of 423 controls were interviewed. Information on pesticide exposures 3 months before pregnancy, throughout pregnancy, and during breastfeeding was obtained. Unconditional logistic regression was used to estimate adjusted odds ratios (aORs) for associations between pesticide exposures and leukemia. RESULTS: Associations with ever use of pesticides during pregnancy were observed for acute lymphoid leukemia (ALL) (aOR = 2.10; 95% CI: 1.14, 3.86) and acute myeloid leukemia (AML) (aOR = 5.01; 95% CI: 1.97, 12.7) in children 0-11 months of age, and with ALL (aOR = 1.88; 95% CI: 1.05, 5.23) at 12-23 months of age. According to reported maternal exposure to permethrin, higher risk estimates were verified for children 0-11 months of age (aOR = 2.47; 95% CI: 1.17, 5.25 for ALL; and aOR = 7.28; 95% CI: 2.60, 20.38 for AML). Maternal pesticide exposure related to agricultural activities showed an aOR of 5.25 (95% CI: 1.83, 15.08) for ALL, and an aOR of 7.56 (95% CI: 1.83, 31.23) for AML. CONCLUSIONS: These results support the hypothesis that pesticide exposure during pregnancy may be involved in the etiology of acute leukemia in children < 2 years of age.