Experimental formation of cleft palate in mice with polychlorinated biphenyls (PCB)

The teratological effect of polychlorinated biphenyls (PCB) was examined using the ddY strain of mouse. PCB in 0.05 ml ethanol was injected daily, subcutaneously into the back of pregnant mice, for 10 days from day 6 of gestation. Cleft palates were found in fetuses at the 18th gestation, with a significant dose response between 10 mg and 50 mg as total body dose of PCB per pregnant mouse. Comparison of these results with simultaneous observations of body weight of dam or fetus, and number of resorbed and dead fetuses, indicated that cleft palate formation was due mainly to the specific effect of PCB and not to its general toxicity. Cleft lip, brachydactyly, and syndactyly were also found. In the control mice receiving no PCB and no treatment, no external malformations were found in 1765 live fetuses. These results demonstrate a teratogenic effect of PCB in the ddY strain of mouse after subcutaneous injection.