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Scientists are researching the possible health effects of a large group of common but little-known chemicals used in water-resistant garments, stain-resistant furniture, non-stick cookware, and many other consumer goods.
Perfluorine and polyfluoroalkyl substances are generally referred to by their multiple acronym PFAS. PFAS are resistant to water, oil and heat, and their use has grown rapidly since the mid-20th century. Thanks to the non-stick properties of PFAS, they are now suitable for various products such as food packaging, umbrellas, tents, carpets and fire-fighting foam. The chemicals are also used in the manufacture of plastic and rubber as well as in the insulation of cables.
In short, they are all around us. And as a result, they have found their way into the soil and, above all, in some regions into our drinking water.
"We find that they contaminate many rivers, many lakes and many drinking water supplies," says Linda Birnbaum, director of the National Institute of Environmental Health Sciences and the National Toxicology Program. "And we find them not only in the environment, but also in people."
"Essentially, everyone has these compounds in their blood," she explains.
It's easy to break – a quality that earned them the nickname "forever chemicals". Some varieties have been in the human body for years, if not decades. Others accumulate in the soil or in the water, forming a source of long-term exposure.
Despite their ubiquity, however, scientists know relatively little about the health effects of most PFAS types.
No PFAS Legal Limit yet
"Despite their everyday use, the scientific knowledge required to fully understand and regulate these chemicals is not as robust as it is "Deputy Administrator of the Environmental Protection Agency Office of Water David Ross said at a PFAS congressional hearing in March.
This year, the EPA has signaled that it is considering a legal safety limit for some PFAS in drinking water, but that it has not acted yet.
Public spending on research on chemicals has increased. The National Institutes of Health, the Environmental Protection Agency, the Centers for Disease Control and Prevention and several state university systems have increased their funding for PFAS studies in recent years.
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"We have more and more fellows studying PFAS in their studies – both mechanistic studies and animal studies," as well as epidemiological studies analyzing large populations, Birnbaum explains. But the work is progressing slowly.
"This is a very broad class of chemicals – probably 5,000 or more – and it seems like new chemicals are constantly being produced," she says.
In most cases in the US Chemical regulations do not require companies to prove that a chemical is safe before they start selling. It is up to the EPO to determine if and under what circumstances a substance is unacceptably dangerous, and such analyzes usually start only when concerns about public health are raised.
So we do not know much about the vast majority of these chemicals, "says Birnbaum.
One approach pursued by scientists supported by the National Institutes of Health is to analyze hundreds of PFAS strains simultaneously. The goal is to identify subgroups of PFAS with similar properties so that scientists do not have to perform toxicity tests on each chemical.
"It is impossible to test 5,000 or more PFAS," explains Birnbaum.
Early studies suggest some health risks
Some of the largest PFAS epidemiology studies in the US were conducted by a science panel as part of a class action against chemical company DuPont from 2005 onwards. The case alleged that thousands of people in West Virginia and Ohio were injured by industrial releases of a PFAS chemical called PFOA.
The jury was composed of three career epidemiologists who both sides of the court approved the scientific evidence – found a "probable link" between long-term exposure to the chemical and certain medical conditions, such as kidney cancer and thyroid disease.
Further studies of both humans and rodents have found similar associations.
"I think there is growing information that at least some members of this class can be problematic," says Birnbaum.
These findings have initially raised a number of new questions Mechanism: how do PFAS chemicals act in the body? It is one thing to see a connection between exposure to a substance and the disease. It is much more difficult to determine a probable route from chemical exposure to disease symptoms.
"We still do not know the exact molecular pathways by which they produce toxicity," explains Jamie DeWitt, a toxicologist who studies PFAS in East Carolina University.
For example, DeWitt and others have published studies with both humans and rodents suggesting that exposure to a PFAS chemical – PFOA – can suppress the body's response to vaccines.
"I'm pretty sure it's a guy" B-cell "is involved in this suppression, says DeWitt," but I do not know why the B-cell does not produce enough antibodies. Signaling molecules that say, "Hey, B cell, make antibodies?" Is something wrong in the B cell itself? Is it the amount of energy the B cell has? We are still trying to figure out these molecular mechanisms. "
Knowing these mechanisms for PFOA could help scientists gauge the potential risks of other PFAS that have a similar structure, she says." Honestly, I think we're just at the beginning. "
The current research rate, says Birnbaum, will take about two years to tackle the toxicity of the entire PFAS group, but scientists and regulators still have many questions to ask.
"As we know these chemicals into the environment, how can we fix these issues? How can we eliminate these chemicals? "She says.
" One question we all have to ask is: what's important? "She says," Do we really need that? Are there some places where we need this class of chemicals to be safe? But if that's the case, we want them to be used in closed systems so they will not escape and pollute the whole world.
Asked about the importance of PFAS, a spokesman for the Fluoro Council, part of the main trading group of chemical companies in the US, defended its widespread use in consumer goods.
"PFAS are a must. "a technology that plays a key role in products ranging from life-saving applications in pacemakers and defibrillators, to the design of lower-emission vehicles and enhanced vehicle safety, to the manufacture of semiconductors, solar cells, and high-performance electronics," said FluoroCouncil spokesman wrote in an email to NPR:
"The vast differences within the PFAS family of chemistry are not immediately apparent to many people," the statement goes on. "While some names sound the same, PFAS have different properties, formulations, uses, and environmental and health profiles."
Living With Uncertainty
Although two years in the world of basic science research are not very long, people who care about their health can feel like an eternity , In response to public concern, some states are already taking action to regulate PFAS emissions and exposure and collect public health information in communities where it is known that the water is contaminated.
"For People Living in Areas When one of its sources of drinking water reaches [of PFAS] high enough to cause concern, there is a great need for information," says Alissa Cordner, a sociologist at Whitman College and one of the organizers of a nationwide PFAS contamination list
"There are so many uncertainties about the extent and consequences of contamination," she explains, and this insecurity scares people. "In terms of people who want to know what's in my drinking water?" Testing is still too expensive.
And even if scientists or authorities test water in a community, the lack of scientific evidence collected so far about PFAS and health makes it difficult for people to know how to respond According to CDC, they do not effectively remove the chemicals.
"I think it's confusing because you have so many chemicals that we know so little about except that they are a member of that great class," says Birnbaum That's confusing, but it's also frustrating. So we're trying to address these issues now. "Regulators, scientists and citizens agree: research results can not be fast enough.