CARDIAC TERATOGENESIS OF HALOGENATED HYDROCARBON CONTAMINATED DRINKING-WATER

Objectives. The purpose of this study was to test the hypothesis that administration of trichloroethylene and dichloroethylene to pregnant r ats during organogenesis would produce a significant fetal cardiac ter atogenic effect. It was also hypothesized that administration of these compounds only before pregnancy would not be associated with fetal ca rdiac teratogenesis. Background. Epidemiologic observations demonstrat ed an increased number of congenital cardiac defects in children whose mother resided in an area with drinking water contaminated by trichlo roethylene and dichloroethylene. A prior provocative intrauterine expo sure study in rats established a positive link between these contamina nts and an increased number of fetal hearts with congenital cardiac de fects. Methods. Sprague-Dawley rats were given pure tap drinking water (control subjects) or water contaminated with high or low dose of tri chloroethylene or dichloroethylene (experimental groups) during prepre gnancy only, prepregnancy and pregnancy or during pregnancy alone. Res ults. A total of 2,045 fetuses were examined. Trichloroethylene or dic hloroethylene delivered exclusively in the period before pregnancy cau sed no increase in congenital cardiac malformations over the control l evel. Compared with the control group, rats exposed to these agents bo th before and during pregnancy, had a significantly greater number of fetuses with congenital cardiac malformations. Trichloroethylene (high dose only) administered only during pregnancy produced a significant increase in cardiac defects. Other fetal variables, including noncardi ac congenital abnormalities, showed no significant difference between control and treated groups. Conclusions. Trichloroethylene and dichlor oethylene administered during organogenesis are cardiac, but not gener al, teratogens. The data indicate that these agents administered in dr inking water to pregnant rats caused an increased number of congenital cardiac defects in rat fetuses.