The Aug. 17 finding comes after the U.S. Geological Survey found in July that perfluoroalkyl or polyfluoroalkyl chemicals known as PFAS, were found in 45 percent of water taps in the United States.

The EPA's separate findings are the latest evidence that these controversial chemicals are widespread in the environment.

PFASs are called "forever chemicals" because they build up and accumulate in a person's body over time instead of breaking down and have been linked to a number of serious illnesses, including cancer and birth defects.

The chemicals are water resistant and do not break down in the environment and can remain in human bodies for years.

The EPA reported that the toxins could affect the drinking water of 26 million people, according to an environmental advocacy organization called the Environmental Working Group which analyzed the latest agency data.

The federal regulator said (pdf) that two of the most dangerous types of forever chemicals, known as PFOA and PFOS, were also found at unsafe levels in between 7.8 and 8.5 percent of public water systems.

PFASs are used in hundreds of household items from cleaning supplies to pizza boxes, which broadens the chance of serious health risks, according to the USGS study.

They were developed in the 1940s with the creation of Teflon, a non-stick coating for cookware, and are now used in everything from clothing, plastic products, cosmetics, and stain removers.

Forever Chemicals Contamination Common Nationwide

The EPA said the cities that had the high concentration of these toxic chemicals were Fresno, California, and Dallas, Texas.

Samples from Fresno had 16 parts per trillion of PFOA and 29 parts per trillion of PFOS, which was 4 and 7.25 times more than the EPA's proposed regulatory limit and 194.3 parts per trillion for PFAS particles.