EPA testing of the chemicals—perfluoroalkyl and polyfluoroalkyl substances, also known as PFAS—have been found in public water supplies in 33 U.S. states.
There are about 3,500 different types of PFAS, and they have been in production since the 1940s.
Some forms of the compounds are expected to remain intact for thousands of years, and they are often dumped into water, the air, and soil during production.
While unsafe levels of PFAS can contaminate drinking water around military bases and factories, the EPA says 80 percent of human exposure to the chemical comes from consumer products in the home.
The Department of Defense also launched a full-scale review of PFAS contamination in water systems in 2016, despite the lack of clear regulatory limits from the EPA.
It reported that 564 of the 2,445 off-base public and private drinking water systems that it had tested contained PFOS or PFOA above the EPA’s advisory limits.
In its water quality report, the EPA said that PFOA was detected in 1 percent of water samples across the U.S.
However, when Eurofins Eaton Analytical—the largest drinking water test lab in the country—reanalyzed the data the EPA didn’t use, it discovered that the PFOA chemical was in almost 24 percent of the samples.
In early 2018, the federal Agency for Toxic Substances and Disease Registry (ATSDR)—a branch of the CDC—launched a nationwide health study on the PFAS water contamination crisis.
For the chemical PFOA, the ATSDR exposure limit was seven times stricter than what the EPA said was safe.