How to reduce PFAS in your drinking water, according to experts

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In the next three years, drinking water in the United States may be a bit safer from potentially toxic chemicals that have been detected in the blood of 98% of Americans.

Perfluoroalkyl and polyfluoroalkyl substances or PFAS are a family of thousands of man-made chemicals that do not break down easily in the environment. A number of PFAS have been linked to serious health problems, including cancer, fertility issues, high cholesterol, hormone disruption, liver damage, obesity and thyroid disease.

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The US Environmental Protection Agency proposed on Tuesday stringent new limits on levels of six PFAS chemicals in public water systems. Under the proposed rule, public systems that provide water to at least 15 service connections or 25 people will have three years to implement testing procedures, begin notifying the public about PFAS levels, and reduce levels if above the new standard, the EPA said.

Two of the most well-studied and potentially toxic chemicals, PFOA and PFOS, cannot exceed 4 parts per trillion in drinking water, compared with a previous health advisory of 70 parts per trillion, the EPA said.

Another four chemicals — PFNA, PFHxS, PFBS and GenX — will be subject to a hazard index calculation to determine whether the levels of these PFAS pose a potential risk. The calculation is "a tool the EPA uses to address the cumulative risks from all four of those chemicals," said Melanie Benesh, vice president of government affairs for the Environmental Working Group, a consumer organization that monitors exposure to PFAS and other chemicals.

"The EPA action is a really important and historic step forward," Benesh said. "While the proposed regulations only address a few PFAS, they are important marker chemicals. I think requiring water systems to test and treat for these six will actually do a lot to address other PFAS that are in the water as well."

For people who are concerned about PFAS exposure, three years or so is a long time. What can consumers do now to limit the levels of PFAS in their drinking water?

First, look up levels of PFAS in your local public water system, suggested David Andrews, a senior scientist at the Environmental Working Group. The advocacy nonprofit has created a national tap water database searchable by zip code that lists PFAS and other concerning chemicals, as well as a national map that illustrates where PFAS has been detected in the US.

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However, not all water utilities currently test for pollutants, and many rural residents rely on wells for water. Anyone who wants to personally test their water can purchase a test online or from a certified lab, Andrews said.

"The most important thing is to ensure the testing method can detect down to at least four parts per trillion or lower of PFAS," he said. "There are a large number of labs across the country certified to test to that level, so there are a lot of options available."

If levels are concerning, consumers can purchase a water filter for their tap. NSF, formerly the National Sanitation Foundation, has a list of recommended filters.

"The water filters that are most effective for PFAS are reverse osmosis filters, which are more expensive, about in the $200 range," Andrews said. Reverse osmosis filters can remove a wide range of contaminants, including dissolved solids, by forcing water through various filters.

"Granular activated carbon filters are more common and less expensive but not quite as effective or consistent for PFAS," he said, "although they too can remove a large number of other contaminants."

Reverse osmosis systems use both carbon-based filters and reverse osmosis membranes, Andrews explained. Water passes through the carbon filter before entering the membrane.

"The important part is that you have to keep changing those filters," he said. "If you don't change that filter, and it becomes saturated, the levels of PFAS in the filtered water can actually be above the levels in the tap water."

Carbon filters are typically replaced every six months, "while the reverse osmosis filter is replaced on a five-year time frame," he added. "The cost is relatively comparable over their lifetime."

Another positive: Many of the filters that work for PFAS also filter other contaminants in water, Andrews said.

Drinking water is not the only way PFAS enters the bloodstream. Thousands of varieties of PFAS are used in many of the products we purchase, including nonstick cookware, infection-resistant surgical gowns and drapes, mobile phones, semiconductors, commercial aircraft, and low-emissions vehicles.

The chemicals are also used to make carpeting, clothing, furniture, and food packaging resistant to stains, water and grease damage. Once treated, the report said, textiles emit PFAS over the course of their lifetimes, escaping into the air and groundwater in homes and communities.

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Made from a chain of linked carbon and fluorine atoms that do not readily degrade in the environment, PFAS are known as "forever chemicals." Due to their long half life in the human body, it can take some PFAS years to completely leave the body, according to a 2022 report by the prestigious National Academies of Sciences, Engineering, and Medicine.

"Some of these chemicals have half-lives in the range of five years," National Academies committee member Jane Hoppin, an environmental epidemiologist and director of the Center for Human Health and the Environment at North Carolina State University in Raleigh, told CNN previously.

"Let's say you have 10 nanograms of PFAS in your body right now. Even with no additional exposure, five years from now you would still have 5 nanograms.

"Five years later, you would have 2.5 and then five years after that, you’d have one 1.25 nanograms," she continued. "It would be about 25 years before all the PFAS leave your body."

The 2022 National Academies report set "nanogram" levels of concern and encouraged clinicians to conduct blood tests on patients who are worried about exposure or who are at high risk. (A nanogram is equivalent to one-billionth of a gram.)

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People in "vulnerable life stages" — such as during fetal development in pregnancy, early childhood and old age — are at high risk, the report said. So are firefighters, workers in fluorochemical manufacturing plants, and those who live near commercial airports, military bases, landfills, incinerators, wastewater treatment plants and farms where contaminated sewage sludge is used.

The PFAS-REACH (Research, Education, and Action for Community Health) project, funded by the National Institute of Environmental Health Sciences, gives the following advice on how to avoid PFAS at home and in products: