[Relation of mutagenicity and teratogenicity]

An analysis of the known causes of congenital malformations reveals the crucial role of mutations during gametogenesis or during the early stages of blastogenesis. The resultant abnormality is then hereditary. Environmental agents and in particular chemical substances have sometimes proved highly deleterious when exposure has occurred during embryogenesis. However, the combination of several causes increases the incidence of certain morphological or functional defects. Mutagenesis and Teratogenesis have little common ground. For each area the risk must be evaluated separately on the basis of sensitive animal models and, in the case of prescreening, in well validated short-term tests.