Effect of chlorine dioxide and its metabolites in drinking water on fetal development in rats

The chlorination of surface waters is known to form trihalomethanes. Therefore, chlorine dioxide (C1O2) is being considered as an alternative disinfectant. This study was designed to determine the effect of chlorine dioxide and its metabolites, chlorite (C1O-2) and chlorate (C1O-3), on rat fetuses exposed in utero. Female rats were administered C1O2 at 0, 1, 10 and 100 mg 1(-1) and C1O-2 or C1O-3 at 1 and 10 mg 1(-1) daily in the drinking water for 2 1/2 months prior to the throughout gestation. Rats were killed on day 20 and fetuses examined for external, skeletal and visceral malformations. Slight decreases in weight gain during pregnancy were seen in the C1O2 administered groups. A significant dose-response relationship in the decreases of the numbers of implants and live fetuses were observed in the C1O2 groups. Although there were increased incidences of resorptions in the C1O-2 and C1O-3 groups, no statistically significant increase was found in the groups. Fetal weight was significantly increased in the 100 mg 1(-1) C1O2 group. Also, fetal length was increased in the 10 mg 1(-1) C1O-2 and C1O-3 treatment groups. Skeletal defects, such as incompletely ossified or missing sternebrae, rudimentary ribs and incompletely ossified skull bones were increased in all treatment groups, but none were significantly different from the control group. A few cases of hypoplastic kidney, hydronephrosis and dextrocardia were observed in the treatment groups.