Use of dose-response relationships to discriminate between the mechanisms of cleft-palate induction by different teratogens: an argument for discussion.

The examples of 6-AN- and cortisone-induced cleft palate in the mouse suggest that dose-response studies can be used to discriminate whether mechanisms of action are different for different teratogens. Evidence for differences in the mechanisms of teratogenic action can be found in terms of the parameters of the response without reliance on other consequences of teratogen treatment. It is argued that the application of established biometrical models or, possibly, the development of new ones is critical to consolidate enumerative data. With practical methods, genetic variation can be sought, interpreted and put to experimental use, structure-function studies can be made intelligible, and safety evaluation programs might begin to make sense.