Maternal Occupational Chemical Exposures and Biotransformation Genotypes as Risk Factors for Selected Congenital Anomalies

In a case-control study using an assessment of occupational tasks by an industrial hygienist, the authors investigated whether women’s occupational exposures increased risks of delivering infants with cleft palate (CP), cleft lip with or without cleft palate (CLP), conotruncal defects, or limb deficiencies. For CP and CLP, exposures were further considered in the presence/absence of infant genetic variants for glutathione-S-transferase M1, glutathione-S-transferase T1, and N-acetyltransferases 1 and 2. The study included 1987–1989 California stillbirths and livebirths. Telephone interviews were conducted with mothers of 662 CLP and CP cases, 207 conotruncal defect cases, 165 limb deficiency cases, and 734 nonmalformed controls. Occupational tasks were assigned to a priori-defined exposure categories: 74 chemical groups and nine “end-use” chemical groups. Odds ratios of 1.5 or greater were observed for a small number of exposure-defect comparisons. Risks associated with end-use groups revealed odds ratios of 1.5 or greater for exposures to dyes and pigments (conotruncal and CP), propellants (CP), and insecticides (conotruncal and CP). Numerous odds ratios of 2.5 or greater were observed for combined effects of exposures and homozygous mutant genotypes, particularly for CP. Although potential associations were observed, most results suggested that maternal occupational chemical exposures did not contribute substantially to the occurrence of these anomalies in this California population.