Household pesticides and the risk of Wilms tumor

Background: Previous epidemiologic studies have suggested that exposure to pesticides in utero and during early childhood may increase the risk for development of childhood cancer, including Wilms tumor, a childhood kidney tumor. Obectives: In this analysis we evaluated the role of residential pesticide exposure in relation to the risk of Wilms tumor in children using data from a North American case-control study. Methods: The National Wilms Tumor Study Group (NWTSG) collected information on exposure to residential pesticides from the month before pregnancy through the diagnosis reference date using detailed phone interviews from 523 case mothers and 517 controls frequency matched on child's age and geographic region and identified by list-assisted random digit dialing. Pesticides were grouped according to type of pesticide and where they were used. Results: A slightly increased risk of Wilms tumor was found among children of mothers who reported insecticide use [odds ratio (OR) = 1.4, 95% confidence interval (CI), 1.0-1.8; adjusted for education, income, and the matching variables]. Results from all other categories of pesticides were generally close to the null. Conclusions: This study is the largest case-control study of Wilms tumor to date. We were unable to confirm earlier reports of an increased risk for Wilms tumor among those exposed to residential pesticides during pregnancy through early childhood.