Maternal residential proximity to oil and gas development in California and the risk of childhood cancer.

This study investigates maternal residential proximity to oil and gas development (OGD) in pregnancy and the risk of multiple childhood cancers in California. Cases (N = 9487) were identified from California Cancer Registry and controls (N = 183834) were randomly selected from the California Birth Registry (20:1 frequency-matched by birth year: 1998-2016), restricting both to births within 10 km of OGD. Exposure was defined as residing within 1 km or 3 km of any well at birth; 'low' and 'high' exposures were defined by the median well count within each distance. Unconditional logistic regression models estimated cancer risks comparing each exposed group to the unexposed (residing 3-10 km from any well). The risks of several cancers among children of mothers exposed to any well increased: medulloblastoma (within 3 km: adjusted Odds Ratio (aOR): 1.40; 95% confidence interval (CI): 1.08, 1.82; low, aOR = 1.27; 95% CI = 0.93, 1.74; high, aOR = 1.55; 95% CI = 1.14, 2.11); rhabdomyosarcoma (within 3 km: aOR = 1.64; 95% CI = 1.28, 2.09) with similar estimates across low and high exposure levels; and teratoma (within 3 km: aOR = 1.42; 95% CI = 0.99, 2.05; low, aOR = 1.35; 95% CI = 0.88, 2.07; high, aOR = 1.51; 95% CI = 0.98, 2.33). The results were consistent across both buffer sizes (1 km and 3 km) and estimates were similar for any well and inactive wells. No clear associations were observed for other major childhood cancers including leukemias and lymphomas. Our study suggests that OGD may increase the risk of developing several rare childhood cancers.