Characteristics of new approaches for evaluation of embryotoxic effects of chemical substances

: New approaches to the evaluation of embryotoxic effects of xenobiotics are characterized in the light of mother--fetus interrelationship. The first part of the paper analyzes problems of evaluating maternal and embryofetal toxicity and substantiates the necessity of sensitive selection and precise evaluation of individual parameters of toxicity. The second part presents a survey of classical testing procedures and of alternative methods used in assessing the safety of new drugs. The third part characterizes methods of quantitative determination of risks inherent to chemical substances. A detailed description of the principles of the new method is presented which is based on the interrelationship of maternal and embryofetal toxicity (adult/developmental--A/D). The acceptability of the new method has been verified experimentally on evaluating some new prospective drugs according to standard teratological studies.