Pre- and Postnatal Exposures to Residential Pesticides and Survival of Childhood Acute Lymphoblastic Leukemia

Background: Exposure to pesticides has been associated with an increased risk of developing childhood leukemia. However, the impact of pesticides on childhood leukemia survival has not been examined. We investigated the associations between residential pesticide use during key developmental periods and 5-year survival in children treated for acute lymphoblastic leukemia (ALL). Methods: Residential use of insecticides, herbicides, rodenticides, and flea control products from preconception up to 12 months prior to diagnosis and sociodemographic characteristics were collected via parental interview among 837 children diagnosed with ALL between 1995 and 2008 in California, USA. Data on clinical features were abstracted from medical records. Vital status was obtained through linkage to the National Death Index (NDI) up to 2020. Cox proportional hazards regression models were used to estimate hazard ratios (HRs), adjusting for sociodemographic factors and clinical risk group. Results: A total of 108 children with ALL (similar to 13%) died within 5 years of diagnosis. Exposure to any pesticides pre- and/or postnatally was slightly higher among deceased compared to alive children (95.4% vs. 91.5%; p = 0.23), while use of rodenticides was significantly higher in children who died (25.0%) vs. those who survived (15.5%; p = 0.02). In fully adjusted models, exposure to rodenticides was associated with an increased risk of mortality (HR 1.70; 95% confidence interval (CI) 1.08-2.64; p = 0.02), especially when the child was exposed during pregnancy (HR 1.90; 95% CI 1.15-3.16; p = 0.01) and possibly 12 months before diagnosis (HR 1.60; 95% CI 0.98-2.61; p = 0.06). Increased hazards of death were also observed with other types of pesticides during pregnancy, but those associations were not statistically significant. Conclusions: This study is the first to report reduced survival among children with ALL previously exposed to rodenticides, particularly during pregnancy, underscoring the need to further evaluate mechanisms by which environmental exposures during key developmental stages may later impact cancer outcomes.