Latest news with #mercury
The Independent
2 days ago
- Health
- The Independent
What is thimerosal? The rarely-used vaccine preservative targeted by RFK Jr
A federal vaccine panel, recently reshaped by the U.S. Health Secretary Robert F. Kennedy Jr. has voted to discourage the use of flu vaccines containing thimerosal, a mercury-based preservative. The decision marks a dramatic shift in vaccine policy, as thimerosal has long been considered safe by health agencies worldwide, with its use already limited to a few multi-dose flu shots. RFK Jr. has long linked thimerosal to autism – a connection that extensive scientific research has thoroughly debunked. Thimerosal is an organic chemical containing mercury, used as a preservative in vaccines since the 1930s. Its effect comes from the mercury that disrupts the function of enzymes in microbes, such as bacteria and fungi. This prevents contamination of vaccines while they are stored in vials. Mercury, however, is also well-known as a potent toxin acting on cells in the brain. Much of mercury's toxicity to brain cells stems from the same attributes that make thimerosal such a useful preservative. It disrupts the basic biological function of cells by changing the structure of proteins and enzymes. In the brain, this can lead neurons to become excessively active, can impair the way they use energy, it can increase inflammation and lead to the death of neurons. While mercury poisoning can damage brain function in adults, babies are even more vulnerable. People have long understood that mercury is toxic. But in the latter half of the 20th century, scientists discovered that industrial mercury entered rivers and seas, accumulating in the tissues of fish and shellfish. The neurological consequences of consuming too much contaminated seafood could be severe. This led environmental scientists to determine safe levels of mercury exposure. Anxiety about mercury in vaccines intensified when it was noticed that some children receiving multiple vaccines could exceed established safety limits for mercury exposure. These limits were based on environmental toxicity studies. How mercury affects the brain, though, depends very much on the chemical form in which it is ingested. Methylmercury v ethylmercury The form of mercury that contaminates the environment as a consequence of industrial processes is methylmercury. The form that is part of thimerosal is ethylmercury. The structure of these molecules differs in subtle but important ways. Methylmercury has one more carbon atom and two more hydrogen atoms than ethylmercury. These small differences significantly affect how each compound behaves in the body, particularly in how easily they dissolve in fats. Fat solubility is a key consideration in pharmacokinetics – the science of how drugs and other molecules travel through the body. Briefly, because cell membranes are made of fatty substances, a molecule's ability to dissolve in fats strongly influences how it crosses these membranes and moves through the body. It affects how a molecule is absorbed into the blood, how it is distributed to different tissues, how it is broken down by the body into other chemicals and how it is excreted. Methylmercury from environmental contamination is more fat-soluble than ethylmercury from thimerosal. This means that it accumulates more easily in tissues and is excreted from the body more slowly. It also means that it can more easily cross into the brain and accumulate at greater concentrations for longer. For this reason, the safety guidelines that were established for methylmercury were unlikely to accurately predict the safety of ethylmercury. Global policy shift amid public fear Nevertheless, concerns about vaccine hesitancy, rising autism diagnoses and fears of a potential link to childhood vaccines led to thimerosal being almost entirely removed from childhood vaccines in the US by 2001 and in the UK between 2003 and 2005. Beyond biological considerations, policymakers were also responding to concerns about how vaccine fears could undermine immunisation efforts and fuel the spread of infectious diseases. Denmark, which removed thimerosal from childhood vaccines in 1992, provided an early opportunity to study the issue. Researchers compared the rates of autism before and after thimerosal's removal, as well as compared with similar countries still using it. Several large studies demonstrated conclusively that thimerosal was not causing autism or neurodevelopmental harm. Despite the overwhelming evidence that thimerosal is safe, it is no longer widely used in childhood vaccines in high-income countries, replaced by preservative-free vaccines, which must be stored as a single dose per vial. Storing multiple doses of a vaccine in the same vial, however, is still an extremely useful approach in resource-limited settings, in pandemics and where diseases require rapid, large-scale vaccination campaigns, common with influenza. International health bodies, including the World Health Organization, continue to support thimerosal's use. They emphasise that the benefits of immunisation far outweigh the theoretical risks from low-dose ethylmercury exposure.
CBC
20-06-2025
- Health
- CBC
Mercury poisoning in Peru's Amazon found in nearly 80 per cent of villagers in recent study
Indigenous and riverine communities in the Loreto region of the Peruvian Amazon have "chronic exposure" to mercury, according to a new study — and experts say the biggest culprit is gold mining in the region. The test results released this month by the Center for Amazonian Scientific Innovation at Wake Forest University (CINCIA) in the United States show nearly 80 per cent of the people tested late last year had levels of mercury far above the safe limits in six communities on the banks of the Nanay and Pintuyacu rivers. "The majority of the population is contaminated," said Jairo Reategui Davila, the Apu, or leader, of San Antonio de Nanay, one of the tested communities. "We call on the authorities to take action on the matter because we are very concerned," he said. The results showed 37 per cent of the 273 men, women and children tested had levels of mercury at more than 10 ppm (parts per million) in their hair, compared to just three per cent under the 2.2 ppm limit established by the World Health Organization (WHO). How did so much mercury get in the environment? The central factor is a lust for gold, according to scientists and officials. Gold prices have soared by nearly 50 per cent in the last year, beating successive record highs, and encouraging a flourishing illegal gold mining trade in the Amazon, where illegal miners use mercury to extract gold particles from the river silt. After the gold is extracted, these mining operations burn off the mercury, turning the toxic metal to vapour that is absorbed by surrounding plants, soil and rivers, said Claudia Vega, head of the mercury program at CINCIA, damaging local nature and biodiversity and raising significant health concerns. Mercury poisoning is associated with several health issues, including cognitive impairment in adults and irreversible developmental delays and learning difficulties for children and babies in the womb. Gabriel Barría, regional coordinator for heavy metals for the local health authority, said it was "very regrettable that villagers were highly contaminated" and blamed the spread of illegal gold mining for the mercury levels in Amazon rivers. He said the health authority did not have the budget to carry out tests for mercury and had only tested 12 villagers on a recent health visit relying on blood and urine samples. Exceeding the limit CINCIA said tests revealed an average level was 8.41 ppm, exceeding the WHO limit by nearly four times. Given that illegal mining in Loreto is fairly recent, there are no comprehensive studies on its health impact on the local population yet. But the levels in these initial tests are already higher than those in the Peruvian Amazon region most impacted by illegal gold mining, Madre de Dios, where 2012 tests showed the majority of adults had average mercury levels of 2.7 ppm. Communities along the Amazon have had to deal with illegal gold mining operations for decades, but it's become a mounting problem in South America in recent years despite governments attempting to crack down on them. In 2023, Colombia, Brazil and the U.S. teamed up to destroy 19 illegal gold mining dredges in the Amazon rainforest. Around 114,000 grams of mercury was being dumped into the river every month at these sites, which authorities said were run by a transnational criminal group. Luis Fernandez, executive director of CINCIA and research professor at Wake Forest University, said if illegal mining continued to spread in Loreto, then villagers with already high mercury levels might begin to approach those close to the worst-recorded cases of mercury contamination. This includes Minamata Bay, the renowned case in Japan in the 1950s, where children were born with congenital deformities and neurological disabilities caused by a chemical factory dumping mercury into the water supply for decades. Vega from CINCIA, who led the study, said the results showed worrying "background" levels of mercury in the Loreto riparian communities. The villagers' fish-based diet was the biggest vector for the mercury entering their systems, Vega said. While this particular study couldn't fully determine if the mercury came from naturally occurring sources or human-caused activities like illegal gold mining, she noted that "several studies agree that the entry of mining into a territory tends to significantly increase mercury levels in the environment." The villagers tested for this newly released study were mainly exposed to methylmercury, researchers found, a highly toxic form that accumulates in the body. "[The] greatest risk is for pregnant women and children: methylmercury can cross the placenta and affect the development of the developing baby's brain," Vega said. "This type of exposure is a serious public health concern, even if affected individuals do not show immediate symptoms."
New York Times
13-06-2025
- Science
- New York Times
Study Shows Mercury Levels in Arctic Wildlife Could Rise for Centuries
Levels of mercury in Arctic wildlife could continue to rise significantly even as countries curb their emissions, a new study suggests. Researchers analyzed more than 700 samples of fish, mammals and peat collected across Greenland over the past 40 years and found evidence that the mercury in them was distributed by ocean currents. The finding, published this week in the journal Nature Communications, helps explain why levels of mercury contamination have continued increasing in the Arctic even as global emissions have begun to plateau. 'We got a lot of surprises when we analyzed the data,' said Jens Sondergaard, a senior ecological science researcher at Aarhus University in Denmark and lead author of the study. 'It's a really striking trend.' Exposure to high concentrations of mercury, a potent neurotoxin, can lead to neurological and other health-related effects and the study confirms that mercury emitted today could continue posing a large threat to humans and wildlife in the region for centuries. eBy analyzing mercury isotopes, a unique kind of chemical signature that can be matched like a fingerprint, the researchers traced the spread of mercury contamination to the patterns of ocean currents around Greenland. Previous research has shown that mercury can persist in oceans for more than 300 years. Want all of The Times? Subscribe.
Wall Street Journal
11-06-2025
- Business
- Wall Street Journal
EPA to Repeal Air-Pollution Standards on Power Plants
WASHINGTON—The Environmental Protection Agency proposed Wednesday weakening air-pollution standards for mercury and eliminating carbon dioxide rules on power plants, reversing Biden-era policies as part of an overall effort to curtail the agency's role in regulating climate change. The easing of the environmental regulations is in line with executive orders issued by President Trump in April to expand coal mining, leasing and exports, and push for greater use of coal-fired power generation.
New York Times
10-06-2025
- Politics
- New York Times
Document Shows E.P.A. Plans to Loosen Limits on Mercury From Power Plants
The Environmental Protection Agency plans to weaken a Biden-era regulation that required power plants to slash pollutants, including the emissions of mercury, a neurotoxin that impairs brain development, according to an internal agency document. Lee Zeldin, the E.P.A. administrator, intends to announce the proposed changes within days, according to two people who have been briefed on the agency's plans. Mr. Zeldin also will release a separate proposal to eliminate limits on greenhouse gases from power plants, according to the people, who spoke on the condition of anonymity because they were not authorized to discuss agency plans. Together, the changes represent a repudiation of efforts taken by the Biden administration to tackle climate change and address the disproportionate levels of air pollution faced by communities near power plants and other industrial sites. Once finalized, likely at the end of this year, both rules are expected to face legal challenges. The moves are part of a broad strategy by the Trump administration to expand the use of fossil fuels, the burning of which is dangerously heating the planet. President Trump has taken several recent steps to try to boost the use of coal, the dirtiest of the fossil fuels. An E.P.A. spokeswoman would not confirm the details of either regulation or when they would be made public. But Mr. Zeldin in a statement said he is 'opposed to shutting down clean, affordable and reliable energy for American families.' 'E.P.A. needs to pursue common-sense regulation to Power the Great American Comeback, not continue down the last administration's path of destruction and destitution,' he said. Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times. Thank you for your patience while we verify access. Already a subscriber? Log in. Want all of The Times? Subscribe.
