A summary of the results of 55 chemicals screened for developmental toxicity in mice.

Fifty-five chemicals, including known teratogens, known embryotoxins, equivocal teratogens, nonembryotoxins, and nonteratogens, as well as compounds of unknown teratogenic or embryotoxic potential, were evaluated in the Chernoff/Kavlock developmental toxicity screen. All chemicals were administered by gavage to pregnant ICR/SIM mice on gestation days 8 through 12. The mice were allowed to deliver, and several neonatal growth and viability parameters were measured in the offspring. Comparative statistical analysis of these parameters between treated animals and concurrent (vehicle-treated) controls provided a data base to evaluate the validity of the developmental toxicity screen as an assay to detect teratogens and embryotoxins. Of the 26 compounds reported in the literature to be teratogenic or embryotoxic in mice following oral administration, 24 were positive in the developmental toxicity screen. Of the compounds previously tested in conventional assays and found to be devoid of teratogenic or embryotoxic activity in mice, 93% were negative in the developmental toxicity screen. The importance of experimental design, dose selection, and neonatal growth and viability measurements as they relate to interpretation and evaluation of the results of the developmental toxicity assay are discussed.