Developmental toxicity of indium chloride by intravenous or oral administration in rats

Pregnant rats were treated with a single intravenous or oral administration of indium chloride (InCl3) on day 9 of pregnancy and their fetuses were examined for growth and malformation on day 20 of pregnancy. By intravenous administration, fetal weight was significantly decreased and the incidences of fetal mortality and malformation were significantly increased at 0.4 mg In/kg. Fetal malformations of the tail and digits, e.g., kinked tail, brachyury, and oligodactyly, were observed at high incidences. By oral administration, similar tendencies in the fetal effects were observed, but there were no significant differences compared to the control even at 300 mg In/kg. Indium concentrations in the serum of pregnant rats showed low bioavailability of indium by oral administration. It was concluded from these results that indium showed teratogenicity in rats. Oral treatment with indium may be developmentally toxic at 300 mg In/kg, but this is difficult to state with certainty given the limited number of animals that were used in this study.