Parental occupational exposures and risk of childhood cancer: a review

We reviewed the literature in order to summarize the present knowledge on the association between parental occupational exposures to chemicals and the risk of childhood malignancy. The 32 studies pertaining to this topic were evaluated by considering various study qualities such as sample size, specificity of outcome, confounding, exposure specificity, and control selection. When evaluating the findings from any epidemiologic study, the potential sources of bias have to be considered. The selection of subjects, misclassification of exposure or outcome, and confounding from extraneous factors can contribute to a biased estimate of effect. Studies done to minimize these potential biases will be more valid, and these studies should be given the most weight when parental occupational exposures are evaluated as risk factors for childhood malignancy. We conclude that the preponderance of evidence supports the hypothesis that occupational exposure of parents to chemicals increases the risk of childhood malignancy. The parental occupational exposures implicated in childhood malignancy risk are exposure to chemicals including paints, petroleum products, solvents (especially chlorinated hydrocarbons) and pesticides, and exposure to metals. The available data do not allow the identification of specific etiologic agents within these categories of compounds. Future epidemiologic and toxicologic studies should be designed to pursue these leads.