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90-Day subchronic toxicity study of sodium molybdate dihydrate in rats
F Jay Murray1, Frank M Sullivan2, Asheesh K Tiwary3
1Murray & Associates, 5529 Perugia Circle, San Jose, CA 95138, USA.
Abstract:
This study investigated the subchronic toxicity of molybdenum (Mo) in Sprague-Dawley rats given sodium molybdate dihydrate in the diet for 90days at dose levels of 0, 5, 17 or 60mgMo/kgbw/day. The study complied with OECD Test Guideline (TG) 408, with additional examination of estrus cycles and sperm count, motility, and morphology from OECD TG 416. The overall no-observed-adverse-effect level was 17mgMo/kgbw/day, based on effects on body weight, body weight gain, food conversion efficiency and renal histopathology (females only) at 60mgMo/kgbw/day. No treatment-related adverse effects on reproductive organ weights or histopathology, estrus cycles or sperm parameters were observed at any dose level. No adverse effects were observed in the high dose animals after the 60-day recovery period, with the exception that male rats did not fully recover from reduced body weight. Serum blood, liver and kidney samples were analyzed for molybdenum, copper, zinc, manganese, iron, cobalt and selenium; high levels of molybdenum and copper were found in the serum, blood, liver and kidneys of rats treated with 60mgMo/kgbw/day. In conclusion, the LOAEL and NOAEL for molybdenum were determined to be 60 and 17mgMo/kgbw/day, respectively.
Insights
The subchronic toxicity study found that molybdenum (Mo) exposure up to 17mgMo/kgbw/day showed no adverse effects in rats. Higher doses impacted body weight and kidney health, establishing the no-observed-adverse-effect level (NOAEL) at 17mgMo/kgbw/day.
Area of Science:
- Toxicology
- Environmental Health
- Nutritional Science
Background:
- Molybdenum (Mo) is an essential trace element, but excessive intake can lead to toxicity.
- Understanding the subchronic toxicity of molybdenum is crucial for establishing safe exposure limits.
Purpose of the Study:
- To investigate the subchronic toxicity of sodium molybdate dihydrate in Sprague-Dawley rats over 90 days.
- To determine the no-observed-adverse-effect level (NOAEL) and lowest-observed-adverse-effect level (LOAEL) for molybdenum exposure.
- To assess the impact of molybdenum on reproductive parameters and organ histopathology.
Main Methods:
- Rats were administered dietary sodium molybdate dihydrate at dose levels of 0, 5, 17, or 60mgMo/kgbw/day for 90 days, adhering to OECD Test Guideline (TG) 408.
- Additional assessments included estrus cycles and sperm parameters (count, motility, morphology) following OECD TG 416.
- Serum, blood, liver, and kidney samples were analyzed for molybdenum and other trace elements.
Main Results:
- The no-observed-adverse-effect level (NOAEL) was determined to be 17mgMo/kgbw/day.
- The lowest-observed-adverse-effect level (LOAEL) was 60mgMo/kgbw/day, associated with reduced body weight, body weight gain, food conversion efficiency, and renal histopathology in females.
- High levels of molybdenum and copper were detected in serum, blood, liver, and kidneys of rats at the 60mgMo/kgbw/day dose.
- No treatment-related adverse effects on reproductive organs, estrus cycles, or sperm parameters were observed at any dose.
Conclusions:
- The NOAEL for subchronic molybdenum exposure in rats is 17mgMo/kgbw/day, with a LOAEL of 60mgMo/kgbw/day.
- While molybdenum accumulation occurred at high doses, significant adverse reproductive effects were not observed.
- The study provides critical data for risk assessment of molybdenum exposure.
