Testing for embryotoxicity.

No animal species exists with which the situation in man can be completely mimicked. This also holds true for non-human primates. With animal experiments only certain aspects of the whole complex situation can be analyzed. In order to achieve this successfully, animal species and experimental set-ups have to be chosen carefully to represent the situation existing in humans in as suitable a model as possible. The more the model deviates from the situation existing in humans, the less will be the predictability. It has to be decided, and this is mainly a political decision, what risk is acceptable. Both terms "risk" and "acceptable" have to be specified. Animal studies beyond routine procedures will have to include the use of more and other species (e.g., primates), and in vitro systems adjusted to the special problem to be solved. Today more information is needed on the pharmacokinetic and "toxico" dynamic properties of old and new chemicals. This will supply data on the embryotoxic/teratogenic doses of a substance or on their non-embryotoxic/teratogenic doses relevant to man. A drastic reduction in the number of chemicals pregnant women are exposed to will greatly enhance the chance to perform experiments on the remaining substances successfully and the chance to obtain valid data.