TRAVERSE CITY, Mich. (AP) — Drinking water from nearly half of America’s taps likely contains “permanent chemicals” that can cause cancer and other health problems, a study says of the government published on Wednesday.

Synthetic compounds known collectively as PFAS are contaminating drinking water to varying degrees in large cities and small towns, and in private wells and public systems, the US Geological Survey said.

The researchers described the study as the first nationwide effort to test PFAS in tap water from private as well as regulated sources. It builds on previous scientific findings that the chemicals are widespread, showing up in consumer products as diverse as nonstick pans, food packaging and waterproof clothing, and finding their way into water supplies.

Because the USGS is a scientific research agency, the report does not make policy recommendations. But the information “can be used to assess exposure risk and inform decisions about whether or not to treat your drinking water, have it tested or get more information from your state” about the local situation, said lead author Kelly Smalling, a hydrologist. investigator.

The US Environmental Protection Agency in March proposed the first federal drinking water limits on six forms of PFAS, or perfluorinated and polyfluorinated substances, which remain in the human body for years and do not break down in the environment. A final decision is expected later this year or in 2024.

But the government has not prohibited companies that use the chemicals from dumping them into public sewage systems, said Scott Faber, a senior vice president at the Environmental Working Group, an advocacy organization.

“We should be dealing with this problem where it starts, instead of putting a traffic light on after the accident,” he said. “We should require polluters to treat their own waste.”

Laboratory animal studies have found potential links between PFAS chemicals and some types of cancer, including kidney and testicular cancers, as well as problems such as high blood pressure and low birth weight.

Federal and state programs typically measure exposure to contaminants such as PFAS in water treatment plants or the groundwater wells that supply them, Smalling said. By contrast, the USGS report was based on faucet samples at 716 locations, including 447 that rely on public supplies and 269 that use private wells.

Samples were taken between 2016 and 2021 in a variety of locations, primarily residences, but also some schools and offices. They included lands protected as national parks; residential and rural areas with no identified PFAS sources; and urban centers with industrial or waste sites known to generate PFAS.

Most of the faucets were sampled only once. Three were sampled multiple times over a three-month period, and the results changed little, Smalling said.

The scientists tested 32 PFAS compounds, most of which are detectable through available methods. Thousands of others are thought to exist, but cannot be detected with current technology, Smalling said.

The most frequently encountered types were PFBS, PFHxS, and PFOA. PFOS, one of the most common throughout the country, also made frequent appearances.

Positive samples contained up to nine varieties, although most were closer to two. The median concentration was around seven parts per billion for the 32 types of PFAS, although for PFOA and PFOS it was around four parts per billion, the EPA’s proposed limit for those two compounds.

The most intense exposures occurred in cities and near potential sources of the compounds, particularly on the East Coast; the urban centers of the Great Lakes and the Great Plains; and central and southern California. Many of the tests, mainly in rural areas, did not find PFAS.

Based on the data, the researchers estimated that at least one form of PFAS could be found in approximately 45% of tap water samples nationwide.

The study underscores that private well users should test their water for PFAS and consider installing filters, said Faber of the Environmental Working Group. Filters containing activated carbon or reverse osmosis membranes can remove the compounds.

The USGS study is “further evidence that PFAS is incredibly ubiquitous and that people who depend on private wells are particularly vulnerable to damage from these chemicals,” Faber said.


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