Exposure to organic solvents during pregnancy and oral clefts: a case-control study.

Prior studies on the relationship between maternal exposure to organic solvents in relation to oral clefts have been inconsistent. We re-examined this relationship in a case-control study conducted in the Rhône-Alpes region of France during the years 1985 to 1989. For each case, we selected two controls without congenital anomalies in the same delivery unit born during the same month. We interviewed each mother within the first five days after delivery about previous reproductive history and exposures during the first two months after conception. If the mother had an occupational activity at that time, we asked her occupational physician to confirm the exposures. We compared maternal exposure to any organic solvent between 200 infants with cleft lip and/or cleft palate and 400 controls and the estimated odds ratio was 1.62 (95% CI 1.04-2.52). Then we compared exposures to nine subgroups of solvents. Only the ratio associated with halogenated aliphatic solvents (4.40, 95% CI 1.41-16.15) was significantly different from unity. Control of potential confounders-sex of child, family history, maternal epilepsy-did not alter this odds ratio estimate.