Childhood leukemia and parental occupation. A register-based case-control study.

To explore possible etiologic factors of childhood leukemia, a case-control study was performed in the Netherlands. Cases were selected from a complete nationwide register of cases of childhood leukemia which were diagnosed between 1973 and 1980. Controls were matched with cases for year of birth, sex, and place of residence at the time of diagnosis. Information about possible exposures was collected by a postal questionnaire addressed to the parents. This report concerns the results of the analysis of parental occupations and occupational exposures for 519 children with acute lymphocytic leukemia and 507 controls. During pregnancy, more mothers of patients were working in "hydrocarbon-related" occupations; relative risk (RR) = 2.5 (95% confidence interval (CI) = 0.7-9.4). Likewise, greater occupational exposure to chemicals (paint, petroleum products, and unspecified chemicals) during pregnancy was found for mothers of patients (RR = 2.4, 95% CI = 1.2-4.6). The kind of work being performed by the mothers one year before diagnosis did not differ between cases and controls. For the fathers, no relationship was found between a hydro-carbon-related occupation or occupational exposure to chemicals and leukemia in the offspring. Adjustment for birth order, social class, and degree of urbanization did not materially change the relative risks.