Study: Nearly half of US tap water contains toxic chemicals

Nearly half of the tap water in the US is estimated to have one or more types of "forever chemicals'' that may cause cancer and other health issues, according to a government study released Wednesday.

The US Geological Survey (USGS) said there are more than 12,000 types of PFAS (polyfluorinated alkyl) substances — collectively called forever chemicals — because they are very slow to break down. The study tested for the presence of 32 types.

The study marks the first time anyone has tested for and compared PFAS in tap water, water from a kitchen faucet, for example, from both private and government-regulated public water supplies on a broad scale throughout the country, the USGS said.

Scientists collected tap water samples from 2016-2021 from 716 locations, from small towns to big metropolitan areas, including protected lands, residential and rural areas with no known PFAS sources, and locations with reported PFAS sources. Of those, 447 locations are public supplies, and 269 locations are private wells.

"USGS scientists tested water collected directly from people's kitchen sinks across the nation, providing the most comprehensive study to date on PFAS in tap water from both private wells and public supplies," said research hydrologist Kelly Smalling, the study's lead author.

"The study estimates that at least one type of PFAS — of those that were monitored — could be present in nearly half of the tap water in the US. Furthermore, PFAS concentrations were similar between public supplies and private wells," Smalling said.

The man-made chemicals are widely used for the linings of products such as fast-food boxes and non-stick cookware to fire-fighting foams. They can build up in the human body and pass from mothers to newborns because of their slow breakdown.

High concentrations of some PFAS may lead to adverse health risks in people, according to the Environmental Protection Agency (EPA). It lists the negative impact of PFAS on reproductivity, children's development, the immune system and the body's natural hormones, as well as increased risk to develop prostate, kidney and testicular cancers; obesity and elevated cholesterol levels.

The study found most of the exposure was near urban areas and potential PFAS sources. The areas included the Great Plains, Great Lakes, Eastern Seaboard, and Central and Southern California regions.

The USGS study's results are in line with previous research concluding that people in urban areas have a higher likelihood of PFAS exposure. USGS scientists estimate that the probability of PFAS not being observed in tap water is about 75 percent in rural areas and around 25 percent in urban areas.

While numerous studies have shown that PFAS are harmful to humans, and further studies are needed to find out more, the US government hasn't regulated the use of the chemicals or prohibited companies from dumping them into public wastewater systems.

For example, a study this year found that more than 21 tons of forever chemicals have been injected into more than 1,000 oil and gas wells across Texas since 2013, and the chemicals could pose a risk to public health.

Scott Faber, a senior vice-president of the Environmental Working Group, an advocacy organization, told The Associated Press: "We should be treating this problem where it begins, instead of putting up a stoplight after the accident. We should be requiring polluters to treat their own wastes."

Agencies contributed to this story.