Occupational exposure to organic solvent mixtures during pregnancy and the risk of non-syndromic oral clefts

Objectives: To examine the association between maternal occupational exposure to mixtures of organic solvents during pregnancy and the risk of non-syndromic oral clefts. Methods: A case-control study ( 164 cleft lip with/without cleft palate (CL/P), 76 cleft palate (CP), 236 controls) was conducted in France to investigate the role of maternal occupational exposure to organic solvents at the beginning of pregnancy in the risk of non-syndromic oral clefts. An expert chemist, guided by a detailed description of the women's occupational tasks, assessed exposure for each. Analysis of the findings used logistic regression. Results: In the control group, 39% of the women who reported working during pregnancy were exposed to at least one type of organic solvent. The risk of oral clefts was associated with oxygenated ( for CL/P: OR=1.8, 95% CI 1.1 to 2.9; and for CP, OR=1.4, 95% CI 0.7 to 2.7), chlorinated ( OR = 9.4, 95% CI 2.5 to 35.3; OR= 3.8, 95% CI 0.7 to 20.7), and petroleum ( OR = 3.6, 95% CI 1.5 to 8.8; OR= 1.2, 95% CI 0.3 to 4.9) solvents. The risk of oral clefts increased linearly with level of exposure within the three subgroups of oxygenated solvents we considered ( aliphatic alcohols, glycol ethers, and other oxygenated solvents, including esters, ketones, and aliphatic aldehydes). Conclusions: Results suggest that maternal occupational exposure to organic solvents during pregnancy may play a role in the aetiology of oral clefts. The limited number of subjects and the problem of multiple exposures require that these results be interpreted cautiously.