THE STATE OF THE ART The recent seventies have not been good times for toxicologists. Public confidence in us is shaken, mostly as a consequence of an unhappy sequence of spectacular failures: we have been surprised by a tragic transplacental carcinogenic effect of diethylstilbestrol, an old and widely prescribed synthetic estrogen. We are confronted with a small epidemic of an unusual liver tumor, angiosarcoma, induced by a simple chemical, vinylchloride, whose insiduous toxic potential we failed to "recognize for years. Our clinical colleagues had to tell us about the ulcerogenic effect of as simple a substance as potassium chloride. We also just learned of an unusual toxic reaction, pseudolupus, developing in people taking a popular fixed-combination drug, venocuran Admit- tedly, we could not have predicted this syndrome, even if we had con- sidered the possibility. We are still unable (to continue this self-flagellation) to explain the relationship between the appetite suppressant arninorex and the sud- denly increased occurrence of a lung disease posing as primary pulmonary hypertension. And worse yet, we have no way to evaluate a new deriva- tive of this class, and to predict whether or not it, too, will produce the deadly condition. We still, to my knowledge, have no plausible ex- planation why and how thalidomide caused phocomelia. Of course, we do diligently a set of teratological experiments with each new drug; we follow a protocol which has the blessing of all governmental regulatory agencies.