Methylmercury exposure and reproductive dysfunction in the nonhuman primate

Area of Science:

• Toxicology
• Reproductive Science
• Primate Studies

Background:

• Methylmercury (MeHg) is a neurotoxin with potential reproductive effects.
• Understanding MeHg's impact on primate reproduction is crucial for human health risk assessment.

Purpose of the Study:

• To investigate the effects of methylmercury hydroxide (MeHg) on the reproductive cycles and outcomes of female Macaca fascicularis.
• To determine the relationship between MeHg dosage, blood mercury levels, and reproductive success or failure.

Main Methods:

• Female macaques were administered 0, 50, or 90 micrograms/kg/day of MeHg orally for approximately 124 days.
• Menstrual cycles were monitored daily throughout the study.
• Females were time-mated to non-treated males to assess reproductive outcomes, including conception and abortion rates.

Main Results:

• MeHg treatment did not significantly affect menstrual cycle length or menses.
• Reproductive failure was associated with higher blood mercury concentrations, though the overall dose-response relationship was not statistically significant.
• Offspring tended to be smaller, but gestation, birthweight, and crown-rump length were not significantly reduced. Toxicity signs appeared in some females at high doses after prolonged exposure.

Conclusions:

• While MeHg did not disrupt menstrual cycles, elevated blood mercury levels were linked to reproductive failure in macaques.
• High-dose, long-term MeHg exposure can lead to toxicity in primates, correlating with maternal size, treatment duration, and blood mercury levels.