Quantitative correspondence betw( activity of teratogenic agents

We have tested 74 teratogenic and 28 nontera- togenic agents in a recently developed in vitro teratogen assay sys- tem. The assay identifies teratogens by their ability to inhibit at- tachment of ascites tumor cells to plastic 'surfaces coated with concanavalin A. There is a qualitative agreement between in vivo animal data and in vitro activity for 81 of the 102 agents (79%). Quantitative analysis shows a highly significant correlation coef- ficient of 0.69 between the inhibitory in vitro dose and the lowest reported teratogenic dose for 54 of the 60 inhibitory teratogens. 'The doses analyzed ranged over 5 orders of magnitude. We in- terpret these results to mean that attachment inhibition in concert with other, complementary, in vitro assay systems can become a useful method for the assessment of the teratogenic potential of environmental agents. To be useful, in vitro assay systems for teratogenic agents should be able to provide a quantitative estimate of teratogenic potency in laboratory animals or in humans. In vivo processes of ab- sorption, placental transfer, and maternal and embryonic me- tabolism make it unlikely that any group of in vitro systems will be able to predict in vivo potency precisely. However, as in vitro systems approach quantitative and qualitative correspondence with in vivo results, they will become increasingly useful in the assessment of the teratogenic risk associated with environmen- tal agents. Our interest in the correspondence between in vitro and in vivo data stems from the need to evaluate the validity of a re- cently developed in vitro teratogen assay (1). Teratogens are identified in the assay by their ability to inhibit the attachment of tumor cells to plastic surfaces coated with concanavalin A. In