Review of the role of potential teratogens in the origin of human nonsyndromic oral clefts.

Oral clefts are common birth defects affecting approximately 1 every 1,000 caucasian newborns. While many syndromes with cleft lip with or without cleft palate (CL/P) or with cleft palate (CP) are recognized, the majority of oral clefts fall into the category of "nonsyndromic oral clefts" and the etiology of this group remains incompletely understood. Investigators agree that oral clefts are multifactorial in origin, with both genetic and environmental factors in their etiology. While animal models have identified several teratogens for oral clefts, their precise relevance for humans remains unclear. The goal of this work is to review literature on environmental exposures potentially associated with non-syndromic oral clefts.