Tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate), a
chelating agent used in the treatment of experimental
metal poisoning, was evaluated for developmental toxicity in pregnant Swiss mice.
Tiron was administered intraperitoneally on gestational days 6 through 15 at doses of 0, 750, 1500, or 3000 mg/kg/day.
Cesarean sections were performed on gestation day 18. All fetuses were examined for external, visceral, and skeletal malformations and variations. Treatment with
Tiron resulted in maternal toxicity at 3000 mg/kg/day as evidenced by a high number of deaths, reduced
body weight during gestation and increased relative liver and kidney weights. There were no significant differences between treated and control animals on the number of total implants, dead fetuses, or sex ratio. However, embryo fetotoxicity was evidenced at 3000 mg/kg/day by a significant increase in the number of resorptions per litter, and a significant decrease in the average
fetal body weight. There were no significant changes in the incidence of abnormalities (expressed as total, individual, external, visceral, or skeletal). The no observable adverse effect level (NOAEL) for maternal and developmental toxicity was 1500 mg
Tiron/kg/day.