Middle-aged women with elevated levels of heavy metals are more likely to have depleted ovarian function and egg reserves, which can lead to an earlier onset of menopause and its negative health effects, shows a new study from the University of Michigan.
Researchers reviewed data from hundreds of women approaching menopause and found that the presence of cadmium, mercury and arsenic in urine was linked to low levels of anti-Müllerian hormone. AMH measures ovarian reserve or the number of eggs available for fertilization or menstruation. Menopause is the time in life when hormonal depletion puts an end to monthly menstruation and triggers many changes in a woman’s health and well-being.
The observed magnitude of the associations between heavy metals and AMH was stronger than the association between smoking and AMH, which is a known risk factor for ovarian reserve depletion, according to the study published January 25 in The Journal of Clinical Endocrinology & Metabolism.
“Widespread exposure to heavy metal toxins can have a major impact on health problems related to premature aging of the ovaries in middle-aged women, such as hot flashes, bone weakening and osteoporosis, increased chances of heart disease and deterioration cognitive”. said the author of the study Sung Kyun Parkassociate professor of epidemiology and environmental health sciences at the UM School of Public Health.
“Our study linked heavy metal exposure to lower levels of anti-Müllerian hormone in middle-aged women. The AMH tells us approximately how many eggs are left in a woman’s ovaries. “It is like a biological clock for the ovaries that can indicate health risks in middle age and later in life.”
Using data from the Nationwide Longitudinal Study of Women’s Health, Park and colleagues reviewed 2,252 repeat measurements of AMH in 549 women within 10 years of their last menstrual period. The women in the study were between 45 and 56 years old and were ethnically diverse: 45% white, 21% black, 15% Chinese and 19% Japanese.
“Given that heavy metals are widespread in the general population and the urinary concentrations of metals measured in our study were comparable to those of the general female population in the United States, the possible adverse effects of heavy metals on ovarian function should be a major public health problem. Park said.
Arsenic, cadmium, mercury, and lead are commonly found in drinking water, air pollution, and some foods, particularly seafood and rice. Metals are considered endocrine-disrupting chemicals that can cause infertility, cancer, and other diseases.
Previous research offers toxicological evidence that heavy metals can negatively affect reproductive health. Only a few studies have explored the associations of cadmium and lead with AMH, reporting that cadmium can alter AMH concentrations in pregnant and premenopausal women between 30 and 45 years of age. The new study focused on perimenopausal women.
According to the study authors, this information may allow researchers to address adverse health outcomes known to be associated with metals and changes in reproductive hormones, such as premature menopause, bone loss and osteoporosis, the increased risks of cardiovascular disease, cognitive impairment and vasomotor symptoms.
“We see this important public health issue, which may also have implications for women of all ages,” Park said.
The researchers say their findings require more research, particularly in a younger population, to fully understand the role of heavy metals as possible ovarian toxicants that decrease ovarian reserves.
Co-authors of the study include: Ning Ding, Xin Wang, Siobán Harlow and John Randolph Jr. of UM and Ellen Gold of the University of California, Davis.