(NEXSTAR) – Concerned about so-called “forever chemicals,” or PFAS, in your tap water?

An interactive map showing contamination at thousands of test sites across the country has been updated with 328 newly-confirmed locations where PFAS has been found, according to the map’s creator, the nonprofit Environmental Working Group.

PFAS are comprised of thousands of different man-made chemicals that go into everything from nonstick cookware, to furniture and firefighting foams.

“PFAS are an urgent public health issue facing people and communities across the nation,” said Environmental Protection Agency Assistant Administrator Water Radhika Fox in a news release. “The latest science is clear: exposure to certain PFAS, also known as forever chemicals, over long periods of time is linked to significant health risks.”

The chemicals, estimated to be in 45% of U.S. tap water, don’t break down naturally in the environment and have been linked to numerous health problems, ranging from damage to the liver and immune system, to some cancers.

In March 2023, the Environmental Protection Agency proposed setting strict limits for PFAS in drinking water – 4 parts per trillion (ppt), which is the lowest detectable amount.

Some of the new test sites highlighted by the EWG far exceeded that number:

CityPFAS detected
Fresno, Calif.Nine types of PFAS at 194.3 ppt
New Castle, Del.Two types of PFAS at 270 ppt
Robeson County, N.C.Nine types of PFAS at 149.7 ppt
Suffolk County, N.Y.Four PFAS at 92.8 ppt
(Copyright © Environmental Working Group)

One site had an exceptionally high amount of PFAS, according to EWG – tests found the chemicals in water at the Yeshiva Farm Settlement in New York at a concentration of 427.6 ppt.

If you’re wondering whether or not your tap water might contain synthetic chemicals known as PFAS, you can enter your address in the updated interactive map, which uses official records and data from public drinking water systems to show where forever chemicals were found to be above and below 4 ppt.

EWG notes that while researchers used the highest quality data available, contamination levels are based on a single point in time and may not reflect changes to the water system or treatment efforts.

The update to the map comes shortly after the Environmental Protection Agency released the initial results of PFAS tests from 2,000 water utilities, which found PFAS above minimum limits at 431 water systems, which serve 26.3 million people, according to EWG.