Developmental risks: epidemiologic advances in health assessment.
NIOSH 1985 May; :1-38
The role of epidemiology in evaluating risks from developmental toxins was discussed. The human reproductive system is said to be very complex and a high percentage of adverse pregnancy outcomes occurs very early in pregnancy, usually before medical care has begun. This poses problems when pregnancy outcome is used as a measure of developmental risk. As a result, regulatory authorities have turned to laboratory animal studies and in-vitro tests to evaluate developmental risks. It is noted that epidemiology has been useful in identifying developmental risks. For example, teratogenic effects of methylmercury (593748), polychlorinated biphenyls (1336363), thalidomide (50351), and diethylstilbestrol (56531) were identified in humans by investigating clusters of cases. Despite their proven value, investigating clusters of cases or adverse reproductive outcomes is a difficult technique, particularly if there is not a large number of subjects or there is no biologically based hypothesis to test. Clusters can produce a significant number of false positives and epidemics can be missed by oversight. Factors affecting dose response in developmental toxicology were discussed. The most important are estimating dose to the fetus, timing exposure to achieve maximum sensitivity of risk, and confounding factors. It is noted that deciding how to apportion risk requires epidemiologic data because animal models cannot simulate risk adequately when human confounding factors are present. Effects of misclassification on biasing of study results were discussed. Methods for improving epidemiologic teratology procedures were considered. Methods have been developed for determining early pregnancy loss by monitoring urine and detecting subtoxic exposures to xenobiotics by measuring changes in enzyme activity. Reproductive outcome surveillance has been improved by a protocol developed by the Centers for Disease Control. This is based on early detection of pregnancy and monitoring all pregnancy outcomes.
Biostatistics; Risk-analysis; Teratogenesis; Developmental-disorders; Health-protection; Dose-response; Reproductive-hazards; Biochemical-indicators
593-74-8; 1336-36-3; 50-35-1; 56-53-1
Infectious Diseases; Disease and Injury
Proceedings of a Symposium on Epidemiology and Health Risk Assessment, Columbia, Maryland, May 14-16, 1985, Centers for Disease Control/NIOSH, 38 pages, 91 references