A study by SWAN researchers and others found evidence that women exposed to toxic metals can experience earlier ovarian aging than women without such exposure. SWAN researcher Sung Kyun Park, Sc.D., M.P.H., is the lead author of the study linking exposure to toxic metals with lower egg counts, as determined by anti-Müllerian hormone (AMH) levels that are a marker of ovarian reserve, in women approaching menopause.
The study titled, Heavy Metals and Trajectories of Anti-Müllerian Hormone During the Menopausal Transition, examined information on 549 middle-aged women from the Study of Women’s Health Across the Nation (SWAN) who were transitioning to menopause and had evidence of heavy metals including lead, arsenic, cadmium or mercury in their urine samples. Researchers analyzed data from AMH blood tests from up to 10 years before the women’s final menstrual periods. They found that higher levels of metal in the women’s urine samples were linked to lower AMH levels, an indicator of diminished ovarian reserve, which means a woman has a lower number of eggs remaining than other women her age and can be a cause of infertility.
The study, whose authors include Ning Ding, Xin Wang, John Randolph Jr., Ellen Gold and Sioban Harlow, was published in The Journal of Clinical Endocrinology & Metabolism in January 2024. The study’s conclusion was that heavy metals including arsenic, cadmium and mercury may act as ovarian toxicants by diminishing ovarian reserve in women approaching the final menstrual period. Diminished ovarian reserve may be linked to health problems such as bone weakness, hot flashes and increased risk of heart disease. Heavy metals such as arsenic, cadmium, mercury and lead are common in drinking water as well as in contaminated foods and air pollution. These are considered endocrine disrupters, which are chemicals that block, interfere with or mimic the endocrine hormones in the body.
Previous studies have linked the presence of heavy metals in women’s urine to advanced reproductive aging, but the mechanisms are not well understood. Disrupted maturation of ovarian follicles that contain an egg and diminished ovarian reserve could be the means by which toxic metals impede reproductive hormones and outcomes of reproductive aging.
“We need to study the younger population as well to fully understand the role of chemicals in diminished ovarian reserve and infertility,” said lead author Park, associate professor of Epidemiology and Environmental Health Sciences, School of Public Health, the University of Michigan in Ann Arbor.
