Effects of chlorine dioxide on thyroid function in neonatal rats

Abstract

Chlorine dioxide (CIO₂), an alternative to chlorine for drinking water disinfection, has been implicated as a potential antithyroid agent (Bercz et al., 1982). Because antithyroid compounds are known to alter neurobehavioral development, the present study was designed to determine if perinatal exposure to CIO₂ affects behavioral activity in rat pups. The activity cage system was designed to monitor the development of locomotor activity of a litter of pups between ages 14–21 d. Pups were exposed to CIO₂ either directly, by gavaging 14 mg/kg?from age 5 to 20 d, or indirectly via their dams’ drinking water in concentrations of 2, 20, or 100 mg/1 from gestation to weaning (21 d postpartum). Although the activity of the indirectly exposed group was not different from controls, the gavaged group showed significantly depressed activity for d 18 and 19 postpartum. The T₄ levels of the 21‐d‐old pups was significantly depressed in the 100‐mg/l CIO₂ group. The gavaged pups showed an even greater T₄ depression, which correlates with their activity levels. These data support the hypothesis that CIO₂ affects thyroid function and suggests that a slight depression in T₄ can result in developmental delays.