Fetal epithelial binding of 1,2-dibromoethane in mice

Whole-body autoradiography and computer-assisted image analysis were used to study the tissue binding of the volatile carcinogenic pesticide 1,2-dibromo[14C]ethane (DBE) in C57BL mouse fetuses. Autoradiograms obtained from pregnant mice in late gestation (day 16-17), showed a high level of non-volatile metabolites in the epithelia of the fetal upper alimentary tract and respiratory tract. As determined by image analysis, the concentration of non-extractable (presumably covalently bound) metabolites in the oral epithelium was three times higher than in the maternal liver (day 17). The concentrations in the junction region of the forestomach and the mucosa of the nasal cavity were equal to that in the maternal liver, whereas the bronchi contained lower levels of non-extractable metabolites than the maternal liver. Autoradiography of excised fetal tissues incubated with DBE showed that high levels of non-extractable metabolites were present in the epithelia of the oral cavity, oesophagus and forestomach also in vitro. The results indicate that the fetal epithelia can activate DBE to products that bind to the tissue; they also raise the possibility that DBE is a transplacental carcinogen in mice.