Parental occupation and Wilms' tumor: results of a case-control study.

Parental occupational exposures for Wilms' tumor were investigated in a pair-matched case-control study. The timing of the exposures in relation to the child's conception and birth was studied, as were the two forms of Wilms' tumor: genetic (prezygotic origin) and nongenetic (postzygotic origin). Cases who were under 15 yr of age at diagnosis during 1970 to 1983 were identified through the registries of three main hospitals treating childhood cancer in the Greater Philadelphia area. Controls were selected by random digit dialing and were matched to cases on race, birth date, and telephone area code and exchange. Because of a low participation rate among blacks, results are reported only for the 88 white matched pairs whose parents participated in telephone interviews. Children whose fathers held jobs in a job cluster that consisted mostly of machinists and welders were at significantly increased risk. The increase was highest for preconception exposure (odds ratio = 5.3, P = 0.006). The effect of preconception exposure was higher for the 26 genetic cases than for the 42 nongenetic cases. The other 20 cases were excluded from the subgroup analyses for various reasons. Further analyses did not elucidate an exposure common to machinists and welders that might explain the findings.