A study reports that a class of synthetic chemicals called PFAS, which have links to cancers and other health issues, are “nearly ubiquitous” in surface waters across the United States.

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Manufacturers use the chemicals, known as per- and polyfluoroalkyl substances or PFAS, to make coatings that resist heat, oils, stains, and water. They apply these materials to various products, including clothing, furniture, food packaging, nonstick cookware, and dental floss.

According to the Centers for Disease Control and Prevention (CDC), the health effects of low PFAS levels in the environment are uncertain.

However, the trouble with PFAS is that they are highly stable molecules and, therefore, don’t break down naturally, earning them the title “forever chemicals.” This means they steadily accumulate not only in the environment but possibly also in people’s bodies.

The CDC note that animal studies suggest exposure to high levels of PFAS can affect growth and development, reproduction, thyroid function, immunity, and the liver.

Around 97% of people in the United States have detectable levels of PFAS in their blood.

Epidemiological studies link high serum levels of two particular PFAS — perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) — to increased cholesterol, thyroid disease, and weakened immunity.

PFOA was formerly used by the chemical company DuPont to make Teflon. PFOS was once an ingredient in Scotchgard, made by 3M.

One study looked at a local population with exposure to high PFOA levels in drinking water due to chemical plant emissions. The research found a link between the substance and kidney and testicular cancers.

The health effects of much lower levels of environmental exposure among the general population are not known.

However, according to a study reported by Medical News Today, females who used particular dental floss brands and regularly ate preprepared food sold in coated cardboard packaging, such as takeout, had higher serum levels of PFAS than those who did not.

The extent of PFAS exposure in people from their drinking water is uncertain.

Now, scientists at the Environmental Working Group, a nonprofit research and campaign group, have analyzed water test data from the Environmental Protection Agency (EPA), the U.S. Geological Survey, and Colorado, Kentucky, Michigan, New Hampshire, New Jersey, North Carolina, and Rhode Island.

The researchers also drew upon published results from their own tests.

They conclude that PFAS are “nearly ubiquitous” in surface water, the main source of drinking water in the U.S.

From these test results, they estimate that the tap water of 18–80 million people in the U.S. may contain combined levels of PFOA and PFOS of at least 10 parts per trillion (ppt).

They further estimate that the water supply of more than 200 million people in the U.S. may contain total levels of PFOA and PFOS of at least 1 ppt.

“We know drinking water is a major source of exposure of these toxic chemicals,” says study co-author Olga Naidenko, Ph.D.

“This new paper shows that PFAS pollution affects even more people in the U.S. than we previously estimated. PFAS are likely detectable in all major water supplies in the U.S., almost certainly in all that use surface water.”

The study appears in the journal Environmental Science & Technology Letters.

In 2020, the EPA began setting a regulatory limit on concentrations of PFOA and PFOS.

At present, there is no federal legal limit for PFAS levels in drinking water, though the agency has issued a “health advisory” level of 70 ppt for a lifetime of exposure to PFOA and PFOS. However, this is not legally enforceable.

Some states have passed their own legal limits for particular PFAS. For example, New Jersey has set a maximum limit of 13 ppt for perfluorononanoic acid (PFNA), and standard limits for PFOS (13 ppt) and PFOA (14 ppt).

The authors note that their analysis was hampered by the small number of different PFAS tested by the EPA, a lack of full data disclosure by private testing firms, and from previous evidence of high reporting limits — below which contamination was not reported.

They also note that their analysis represents contamination levels at particular points in time and may not reflect levels today.

The EPA has identified over 600 PFAS in active use in the U.S. However, more than 5,000 chemically defined PFAS exist worldwide.

In conclusion, the study authors call for more testing for a wider range of compounds.

“[C]omprehensive testing of public water systems and private wells with sensitive analytical techniques is needed to define the total concentration of PFAS compounds, as well as identify and address the sources of PFAS pollution in drinking water sources. Testing for total PFAS concentration is especially important, given that different PFAS share similar toxicity characteristics.”