arsenic

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.

December 15, 2022

Climate change brings new urgency to threats posed by abandoned California gold mines

By Leah Campbell

On the western slopes of the Sierra Nevada mountain range in California sits the small town of Nevada City, a historic Gold Rush community where prospectors once mined for riches in the creek that ran alongside town. Today, it’s a popular tourist destination known for its easy access to the picturesque Yuba River and the region’s famed ski resorts.

Belying the welcoming charm of Nevada City, just a few miles to the south lies a different sort of legacy – a 30-acre plot of toxic desolation known as the Lava Cap Mine where arsenic-laden waste from decades of gold and silver mining has contaminated area soils and water. In 1997, a log dam built to contain the debris collapsed in a winter storm and roughly 10,000 cubic yards of mine waste – enough to cover almost five football fields – washed through creeks and into a nearby lake.

For more than two decades now, the site has been on the Environmental Protection Agency’s (EPA) Superfund list, one of thousands of locations designated as posing “unacceptable risks to human health and the environment.” Clean-up efforts are still in progress at Lava Cap.

Lava Cap is among many abandoned hardrock mines strewn through what Californians call “Gold Country.” State and federal officials estimate that there are almost 50,000 such mines in California and more than 160,000 overall across the western United States. Not all are contaminated, but those that are continue to leach out toxic substances, experts say.

Cleanup of these sites take years and cost millions of dollars. But now, climate change is creating new urgency amid fears that more frequent and volatile flooding and out-of-control wildfires will further spread the toxins.

“There’s been decades of research about remobilizing of mine waste by floods,” said Sheila Murphy, a hydrologist with the US Geological Survey (USGS) who has studied the impacts of extreme weather on mine-contaminated watersheds. “One of the issues is when these big floods then move the sediment into streams or reservoirs,” she said. “It’s just sitting there vulnerable to being remobilized over time.”

Murphy is just as concerned with fire as she is with floods. Changes to the soil, ash buildup, and the burn-off of vegetation after a fire means that fire-scarred lands are more prone to floods and mudslides, not just for a single season, but potentially for several years after a fire.

When it comes to the remobilization of contaminated mine waste because of flooding, “fire puts that on steroids,” Murphy said.

December 15, 2022

Arsenic-laden drinking water drives antibiotic resistance, study says

Exposure to arsenic through drinking water has long been recognized as a serious risk to human health. This month, two studies underscore the extent of the ongoing threat, presenting fresh evidence regarding how arsenic exposure contributes to antibiotic resistance, and how the overall health risks are disproportionately borne by Hispanic and American Indian communities.

“Reducing exposure to arsenic is important given the numerous health effects,” said Ana Navas-Acien, a professor of environmental health at Columbia University and an author on a new study identifying racial and ethnic inequalities associated with arsenic pollution.

Arsenic is naturally occurring in the earth but is highly toxic in its inorganic form. It has been used for decades for a range of industrial purposes. Long-term exposure to the chemical is associated with some cancers as well as developmental problems, an increased risk of diabetes, pulmonary disease and other diseases, according to the World Health Organization (WHO).

An estimated 140 million people in at least 70 countries have been drinking water containing arsenic at levels above the WHO provisional guidelines, the organization states.