The fetal distribution of some aliphatic chlorinated hydrocarbons in the rat after vapor phase exposure.

Rats, on the 17th day of pregnancy, were exposed for five h to several different concentrations, ranging from about 100 to 3,000 ppm, of methylene chloride, 1,2-dichloroethane, chloroform and trichloroethylene. Immediately following exposure, the concentrations of these compounds were determined in each fetus and in the maternal blood and characterized as a function of the administered dose. Fetal weights and fetal concentrations were related to their position on the two horns of the uterus. Fetal weight distribution conformed with observations previously reported [Withey and Karpinski 1983, Barr et al. 1969]. Fetuses at either end of each branch of the uterine horns had the lowest concentration of trichloroethylene. The data for methylene chloride and dichloroethane revealed a linear decrease in fetal concentration with the location of the fetus from the ovarian to the cervical end of the uterine horns. These relationships were consistent across doses. Fetal chloroform concentrations did not appear to be related to fetal position. Good linear relationships between the mean fetal concentrations and the maternal blood concentrations with exposure level were observed for the four compounds used in this study.