| We conducted a case-control study to estimate the effects of parental occupational exposures to specific aromatic hydrocarbons (i.e., benzene, toluene, and xylene) and classes of pesticides (i.e., insecticides, herbicides, and fungicides) on the risk of brain cancer in children. Cases were identified between 1986 and 1989 at any of 33 hospitals in the United States and Canada, and included 155 children diagnosed with astrocytoma and 166 children diagnosed with primitive neuroectodermal tumors (PNET). One control per case was selected by random-digit telephone dialing, and was matched by race, age and geographic area to the case child. Telephone interviews with both parents included a complete history of jobs held by fathers for 6 months or more since the time they left high school, and the usual occupation held by mothers before the pregnancy. Information available for each job included the type of business, the job title, the job tasks, and the products used. Job modules were used for 13 occupations to collect more detailed information on the products used and tasks performed in these jobs. All information available for each job was evaluated for potential exposure to the three hydrocarbons and the three classes of pesticides. Each job was assigned a probability, intensity, and frequency of exposure to calculate measures of cumulative and average exposure for each subject. Conditional logistic regression was performed for each histology subtype to calculate the exposure odds ratio as an estimate of the incidence rate ratio. We found some evidence for an association between astrocytoma, but not PNET, and paternal exposure to the three hydrocarbons when cumulative measures of exposure were used and analyses were restricted to non-proxy respondents. For mothers, we did not observe increased risks of either astrocytoma or PNET in relation to hydrocarbon exposure. There was some indication of an association between astrocytoma and parental exposure to pesticides based on moderately elevated risks observed for a dichotomous exposure measure. These results provide justification for future research on the role of parental occupational exposures to pesticides and aromatic hydrocarbons in the etiology of childhood brain cancer. |
