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Toàn quốc The EPA is cracking down on PFAS in drinking water


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The Environmental Protection Agency has announced new and updated drinking water health advisories surrounding per- and polyfluoroalkyl substances–two chemicals that are widely referred to as PFAS and have been linked to harmful health effects in humans and animals.
In a June statement released by the EPA, the agency said it was issuing four drinking water "PFAS health advisories in light of newly available science and in accordance with EPA's responsibility to protect public health." The new advisories indicate the level of PFAS drinking water contamination below which adverse health effects are not expected to occur.
The agency also said as part of its announcement that it was making $1 billion in grant funding available to states and territories across the country to help address PFAS and "other emerging contaminants in drinking water." The first $5 billion from that funding is earmarked to reduce PFAS in drinking water in small and disadvantaged communities that the agency said are facing disproportionate impacts from the harmful chemicals.
But what are PFAS? And why are they cause for concern? Here's a closer look at where these chemicals come from, how they impact public health, and why they're the subject of four new lifetime drinking water health advisories.
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What Are PFAS?
A class of manmade chemicals invented in the 1930s, PFAS became widely used during the 1940s and 1950s in a variety of products and manufacturing processes. Teflon, for instance, was originally produced using Perfluorooctanoic acid (PFOA), while Perfluorooctane sulfonic acid or PFOS was used in firefighting foams, and to coat carpets, making them stain resistant. PFAS chemicals have also been used as part of the manufacturing process for everything from water-repellent clothing to some cosmetics and products designed to resist grease, water, and oil.
"There's so many different products and processes," Jamie DeWitt, PhD, a professor of pharmacology and toxicology at the Brody School of Medicine at East Carolina University told Health. "Because of their use and incorporation into these products, that's [what has] led to their presece in the environment."
As the Agency for Toxic Substances and Disease Registry explains on its website "during production and use, PFAS can migrate into the soil, water, and air. Most PFAS (including PFOA and PFOS) do not break down, so they remain in the environment." PFAS chemicals are particularly problematic because they are resistant to oil and water and not easily interfered with by other chemicals or heat.
Because they're extremely slow to break down in the environment and in the human body, PFAS have been dubbed the "forever chemicals." Though they do not literally last forever, it likely takes centuries for them to break down in nature. Some types of PFAS also remain inside the bodies of living organisms for years, said DeWitt.
PFAS are found all over the world, though people who live near places like landfills, military bases, and manufacturing plants might have particularly high amounts of PFAS in their drinking water.
Due to increasing knowledge surrounding their toxicity, the major manufacturers of products that included PFOA and PFOS, including 3M and DuPont, agreed to voluntarily phase them out in the United States in the 2000s, but they are still used around the world. Other types of PFAS are still produced in the U.S.

Health Impacts of PFAS
DuPont and 3M suspected PFOA was toxic as early as the 1960s, with internal research through the 1980s showing it could enlarge the liver and cause birth defects in animals.
After a class action lawsuit against DuPont in 2001, data collected from exposed people by the C8 Health Project revealed "probable links" between PFOA exposure and high cholesterol, ulcerative colitis, thyroid disease, testicular cancer, kidney cancer, and pregnancy-induced hypertension (PFOA is also called C8).
More recent research continues to uncover additional health effects. The EPA mentions findings that the two chemicals decrease how well vaccines work in children as the basis for updating its advisories. Other research may link the chemicals to cardiovascular damage, decreased birth weight in children exposed during in utero, high cholesterol, cancer, liver disease, and preeclampsia, a severe pregnancy complication, said DeWitt.
Researchers still don't fully understand how exactly PFAS might cause the health problems they've been linked to. They may interfere with the body on a molecular level, disrupting chemical pathways our bodies need to work correctly, though it's not entirely clear how, said DeWitt.
"That's the million-dollar question," she added. "There are hypotheses about how these health problems get caused...We do know that PFAS at the molecular level can interact with many different receptors in our bodies. And this interaction with receptors can change how some of the basic processes in our bodies function. And when those changes occur, over time they can become negative or adverse health outcomes or these diseases."
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Ramifications of The New EPA Advisories
The newly issued EPA advisories for PFOA and PFOS are lifetime drinking water health advisories—upper limits of the amount of these substances that the EPA says are likely to be safe to be exposed to over a lifetime. The advisories aren't mandatory, but the EPA recommends that utilities tell customers if their water is contaminated.
The new levels included in the advisories also set the stage for legal limitations on the substances later in 2022, called Maximum Contaminant Levels (MCLs).
After that point, if utilities detect these PFAS in their water above the levels indicated by the EPA, they will need to find a way to provide water free of the substances. This effort could involve installing expensive filtration systems or obtaining water from another source.
The current advisory levels, however, are so low that it likely wouldn't be a practical MCL, Rainer Lohmann, PhD, a professor of oceanography at the University of Rhode Island, told Health.
The levels included in the advisories are 0.004 parts per trillion (PPT) for PFOA and 0.2 ppt for PFOS. The previous health advisory, set in 2016, was 70 ppt for both substances combined.
"We can't actually measure that low," said Lohmann. "Basically they're just saying, if we detect it, it's too much."The EPA's proposed MCLs will likely end up being a compromise between what is ideal for health and what is feasible for utility companies, he said.

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