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 modern 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 em-bryogenesis 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 substances have not yet been tested on embryos, and other experiments have yielded insufficient data. In addition, persuasive information has been received, from USSR-US collaborative efforts (/, 2) that is indicative of the teratogenic and embryotoxic effect of several pesticides and industrial poisons (3, 4). Hence, the presence of potential teratogenic agents in environmental pollution can no longer be ignored; but which of these factors presents a danger to human embryogenesis? It is necessary to learn how these factors influence embryogenesis; if not for all of them, at least for those chemical contaminants most frequently found in environmental pollution. However, the number of chemical substances is extremely large and is rapidly growing. The routine methods of testing for teratogenicity are extremely laborious and very time-consuming. To screen for teratogenicity by means of present-day methods for just the basic chemicals of environmental pollution would require the efforts of a large number of laboratories and would require considerable material resources. It is impossible to solve this problem in the immediate future. It seems doubtful whether it is worthwhile to test all the chemicals of the environment in sequence. Rather it would probably …