[A study of environmental factors before and during pregnancy in childhood malignancy].

To determine risk factors in childhood malignancy, we compared parental and fetal exposure rates of some environmental factors among major children's malignancies based on 2722 cases of the Japan Children's Cancer Registry Database. The rates of parental exposure to irradiation, chemicals, and maternal dosage before and during pregnancies and of maternal smoking and drinking habit during pregnancies were slightly but statistically significantly high in some blastomas in which loss of heterozygosity of the genes has been reported. On the other hand, there were no significant correlations with these factors in leukemia and malignant lymphoma, which have been reported to be related to special chromosomal translocations. These possible risk factors should be examined by experimental and more detailed epidemiological studies.