reproductive health

January 25, 2024

Heavy metal exposure linked to problems for middle-aged women

By Shannon Kelleher

Women with higher exposure to heavy metals may have fewer eggs in their ovaries as they near menopause compared to others the same age, a condition linked to hot flashes, weak bones, heart disease, and other health problems, according to a new study in more than 500 middle-aged women.

Exposures to cadmium, arsenic, and mercury, in particular, were linked to lower levels of a hormone that strongly correlates with the number of eggs left in a woman’s ovaries, according to the study, which was published Jan. 25 in The Journal of Clinical Endocrinology & Metabolism.

“Our findings suggest that even low exposure to these ubiquitous metals may influence women’s reproductive health,” said Sung Kyun Park, a professor of epidemiology and environmental health science at the University of Michigan and an author of the study.

“Although individual women may reduce exposure by avoiding foods contaminated with toxic metals and limiting the use of the known sources of metals, a more important approach is to reduce exposure at the population-level through legislation and regulations,” he added.

While heavy metals are known to have toxic effects on the reproductive system, little research has investigated whether exposure to low levels of these metals can influence how many eggs women have in their ovaries as they approach menopause, which begins for most women between the ages of 45 and 55.

“Epidemiological evidence is scanty,” said Park, noting that studies relying on animal models have shown a potential link between toxic metals and altered ovarian function.

January 10, 2024

Doctors raise alarm on dropping global fertility rate, environmental pollutants cited

By Shannon Kelleher

Health researchers from around the world are sounding an alarm on a persistent drop in fertility rates, pointing to environmental pollutants among a wide range of factors that they argue need to be urgently addressed in a paper published Wednesday.

Both male and female reproductive health is deteriorating, especially in industrialized regions, suggesting important roles of environmental factors, such as endocrine-disrupting chemicals and pesticides, the authors of the paper state. Studies indicate that the global fertility rate is dropping, with 93% of all countries worldwide expected to dip below levels necessary to keep populations from shrinking by 2100.

The trend is driven, in part, by the impacts of exposure to toxic chemicals, as well as lifestyle factors such as smoking and obesity, according to the 11 researchers authoring the paper, which was published Wednesday in the journal Human Reproduction Update. The researchers – who come from multiple countries, including the United States, Australia, South Africa, Greece, and Denmark – reviewed dozens of studies in coming to their central conclusion that public policy, research and medical access must be stronger on the topic of fertility.

In conjunction with the publication of the paper, the International Federation of Fertility Societies (IFFS), which represents fertility societies in 65 countries, is launching a global campaign Wednesday seeking to push policymakers to make fertility care more affordable, accessible, and equitable, and to adopt policies that aid fertility, including reducing exposures to air pollution and other harmful chemicals linked to reproductive harm.

The paper says that “due to multiple societal and environmental changes, it is important to emphasize that globally between 48 million couples and 186 million individuals of reproductive age live with infertility.” They call infertility “a common chronic disease affecting many reproductive-age women and men.”

Data on the decline in total fertility rate around the world – the number of children each woman gives birth to, a critical factor in population growth – is “pretty remarkable,” said Tracey Woodruff, a professor at the University of California, San Francisco School of Medicine who was not involved in the paper.

“This is really an important issue because it impinges on people’s ability to choose pregnancy should they want to choose pregnancy,” said Woodruff

Among environmental pollutants, endocrine-disrupting chemicals, in particular, are a fertility concern, she said. “We know that the number and amount of them are increasing and we know that some of them can directly impact male and female reproductive health.”

It is difficult to fully calculate the role of environmental pollutants in infertility since “we only have data on a very small proportion of endocrine-disrupting chemicals to which we’re exposed,” she added.

About one in six people struggle with infertility, according to the World Health Organization. Research suggests sperm count in men has declined by 1.6% per year since 1973, although the impact on global fertility is unknown, the paper states.

September 26, 2023

PFAS posing threat to wildlife, scientists say

Wildlife exposure to per- and poly-fluoroalkyl substances (PFAS) poses added added threats to species already struggling to adapt to habitat loss and harmful climate change, a new paper warns.

In a discussion paper published Tuesday in Science of the Total Environment, scientists wrote that there is enough evidence of the toxicity of persistent chemicals such as PFAS in humans to cause substantial concern about the same chemicals’ impacts on wildlife. Considering toxic chemicals’ health harms to wildlife is especially important, they write, as multiple pressures cause steep drops in biodiversity worldwide.

“There’s an incredible body of scientific evidence linking PFAS to health harms in humans, and this should really serve as an indicator of the potential health harms that may be occurring in wildlife globally,” said David Andrews, a co-author on the paper and a senior scientist at the Environmental Working Group (EWG), an environmental advocacy group.

PFAS are commonly used for their stain- and water-resistant properties and have been used for years as a common ingredient in firefighting foam and many household products. Almost all US residents have PFAS in their blood, and the chemicals contaminate water systems serving millions of people nationwide. PFAS are abundant in the natural environment, as well: According to one analysis by the Waterkeeper Alliance, over 80% of natural waterways are contaminated with the chemicals.

Toxic across taxa
There are thousands of types of PFAS, and scientists have found evidence that many can impair the immune system and spur developmental and reproductive problems, as well as cause thyroid and hormone disorders, liver problems, cancers, and nervous system effects.

“What we know [about health harms] in humans indicates that this is a threat to wildlife species globally,” said Andrews.

November 10, 2022

Pregnant mothers’ PFAS exposure may affect adult sons’ sperm quality

By Shannon Kelleher

A study that included more than 800 young Danish men found associations between levels of PFAS in their mothers’ plasma during early pregnancy and lower sperm quality when the men reached young adulthood.

The findings, which were published October 5 in the journal Environmental Health Perspectives, suggested that combined maternal exposure to seven of these toxic “forever chemicals” was associated with male offspring who grew up to have lower sperm concentrations, lower total sperm counts, and higher proportions of sperm that cannot travel normally (or at all).

The scientists identified one particular PFAS, perfluoroheptanoic acid (PFHpA), as the main contributor to all three effects on sperm quality, although they caution that more research is needed to confirm whether the chemical really has an outsized effect.

“This could mean that PFHpA is very potent or has a higher placental transfer than the other PFAS,” said Sandra Søgaard Tøttenborg, a professor at the University of Copenhagen in Denmark and an author of the study. “It could also be a chance finding, considering the multiple comparisons we’ve made and the low concentrations of PFHpA. Before we have other studies to compare with and a more evidence on the mechanisms, we don’t put too much emphasis on this finding.”