Topical problems and basic developmental trends of investigations concerning the embryotoxic and teratogenic effect of environmental chemicals.

The development of effective methods for prevention of embryo disorders and congenital defects appears to be one of the cardinal tasks of modem medicine. The development of man and the health of future generations depends upon a successful solution to this complex problem. The etiology of congenital defects in humans is multifactored since they occur as a result of the injurious effect of environmental agents (so-called teratogenic agents) or because of genetic factors (mutant genes and chromosome aberrations). They also occur as a result of the combined effects of teratogenic agents and genetic factors. The latter is the most frequent etiology of developmental abnormalities. It follows then, that first there exists the necessity of studying the embryotoxic and teratogenic effects of various environmental factors. Secondly, there is the advisability of conducting investigations in an uninterrupted sequence with analysis of the genetic factors facilitating the occurrence of the teratogenic effect. It should be emphasized that the effect on embryogenesis of mammals and humans (with different external agents) has not been studied to the same extent. Extensive information has been accumulated concerning the teratogenic effects of ionizing radiation and pharmacological substances, but the teratogenic properties of chemical components of environmental pollutants have not been studied (in animals) sufficiently. Many of these chemical sub-