Nearly half of US tap water contains toxic 'forever chemicals'

Nearly half of the tap water in the United States 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 this past week.

The US Geological Survey said there are more than 12,000 types of polyfluorinated alkyl, or PFAS, 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 survey said.

Scientists collected tap water samples during 2016-21 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.

"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 human-made chemicals are widely used for the linings of products such as fast-food boxes and nonstick cookware to firefighting 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, or 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.

Agencies contributed to this story.