Morphology and Pathogenesis of Cardiovascular Malformations Induced by Dichloroethylene (DCE) in Chick Embryos

The existence of hazardous chemical wastes in drinking water has always been a social problem. In a particular epidemiological study, the preva-lence of congenital cardiac defects in a very localized industrial area contami-nated by industrial chemicals, such as dichloroethylene (DCE) and trichloro-ethylene (TCE) was relatively highs. The report gave clear evidence of the teratogenicity of DCE and TCE, and warnings were issued. The proportion of offspring with congenital heart defects was greater for parents exposed during the critical period of fetal development of the cardiovascular system. In our previous study, experiments with chick embryos revealed significant cardiac teratogenesis and abnormal tissue dynamics, particularly if TCE was introduced in early stages of developer ent . The purpose of the present investigation was to determine whether DCE would also cardiac anomalies associated with func-tional and histological changes encountered in the TCE experiment using chick embryos. Also, electro-physiological changes were followed to find evidence of the pathophysiological mechanisms. Early on day 4 of incubation, 0.05 ml of 15 μM or 20μM DCE solution was administered on the chorioallantoic membrane of developing chick embryos. A wide spectrum of cardiovascular malformations was noted in the DCE experimental group. Abnormal electro-cardiographic changes including low voltage QRS and ST segmental variations were observed 6 to 30 minutes after DCE application. Ultrastructually, the cellular degeneration of the embryonic myocardium was quite prominent, especially in the primitive ventricular area. Comparing the cardiac anomalies of the TCE experiment with those of the DCE experiment, DCE induced a lesser degree of developmental arrest type cardiovascular anomalies.