IMPACT OF THE ENVIRONMENT ON REPRODUCTION FROM CONCEPTION TO PARTURITION

Consideration of environmental influences on human reproduction must i nclude an investigation of the socioeconomic factors that play an impo rtant role in embryo-fetal development- Nutritional factors are of pri me importance, and modern methods of food production and supply have l ed to new hazards for pregnant women. For example, pregnant women have been advised in a number of European countries not to eat liver due t o the very high concentration (frequently exceeding 100,000 IU per 100 g) of vitamin A. The clear demonstration that periconceptional vitami n supplementation can dramatically reduce the recurrence rate of neura l tube defects suggests that folic acid deficiency may be common even in otherwise well-nourished women. Modern methods of food production m anufacture and sale have increased the risks of Salmonella and Listeri a infections in pregnancy. The dangers of social drug use, especially alcohol and tobacco, are discussed. The types of adverse effect that c an result from chemical exposure during the different stages of pregna ncy is reviewed with a discussion of some of the problems of epidemiol ogical studies in attempting to identify toxic chemicals. The extent o f the ignorance concerning the reproductive toxicity of industrial and environmental chemicals is emphasized by the fact that data are avail able on only a small percentage of even the high-production volume (10 00 tons/year) chemicals. The evidence of reproductive toxicity from ex posure to lead, methyl mercury, polychlorinated biphenyls, polychlorin ated dibenzofurans, and hexachlorobenzene are briefly reviewed. Some a reas of research needs are discussed with emphasis on nutrition, food production, preparation, and storage and the new problems that may be introduced by genetic manipulation. The lack of information on the rep roductive toxic potential of the majority of industrial chemicals nece ssitates a formal mechanism to screen for possible hazards.