Postnatal toxicity of chronically administered paraquat in mice and interactions with oxygen and bromobenzene

Abstract

The purpose of this study was to investigate the effect of chronic paraquat administration on developing mice and to examine the interaction of chronic paraquat exposure with 100% oxygen and the hepatotoxin bromobenzene. Paraquat was administered at 50 and 100 ppm in the drinking water to pregnant mice beginning at Day 8 of gestation, with continued exposure to the newborns up to 42 days after birth. Neither paraquat treatment altered the postnatal growth rate; however, 100 ppm but not 50 ppm paraquat significantly increased the postnatal mortality. Both 50- and 100-ppm paraquat-treated mice were sensitized to the onset of oxygen toxicity, determined by a significant reduction in the LT50 at 42 days after birth. An enhanced sensitivity to oxygen toxicity was also detectable in 100 ppm but not 50 ppm mice at Days 1 and 28 after birth. In 42-day-old mice, 50 and 100 ppm paraquat treatment also significantly reduced the LT50 after 3100 mg/kg ip (LD85) bromobenzene. These observations suggest that the toxicity of paraquat may be mediated through an interaction with oxygen and describe possible interactions that could occur with the environmental use of paraquat.