A two-generation reproductive toxicity study of sodium molybdate dihydrate administered in drinking water or diet to Sprague-Dawley rats

•An OECD TG-416 two-generation reproductive study of Mo as sodium molybdate dihydrate.•Rats given 0, 5, 17, or 40 mg Mo/kg/day in drinking water or 40 mg Mo/kg/day in diet.•Assessed estrus cycle, sperm, mating, fertility, litter size, pup survival & growth.•No adverse effect on reproductive function at any dose level in either generation.•NOAELs: 17 & 40 mg Mo/kg/day for systemic & reproductive toxicity respectively. In an OECD Test Guideline 416 multigenerational study, groups of 24 male and 24 female Sprague-Dawley rats were administered sodium molybdate dihydrate at 0, 5, 17, or 40 mg molybdenum (Mo)/kg bw/day in the drinking water or 40 mg Mo/kg bw/day in the diet over two generations to assess reproductive toxicity. No adverse effect on reproductive function was observed at any dose level in either generation as indicated by no significant dose-related effect on estrus cycles, sperm parameters, mating, fertility, gestation, litter size, pup survival, growth or postnatal development. Systemic toxicity, including decreased body weight, food consumption (males only) and water consumption, was observed among both sexes given 40 mg Mo/kg bw/day in the diet. Serum levels of Mo and copper were increased in a dose-related manner. The No Observed Adverse Effect Levels (NOAEL) are 17 mg Mo/kg bw/day for systemic toxicity and 40 mg Mo/kg bw/day for reproductive toxicity.