PARKERSBURG — A federal study on the levels of perfluorinated chemicals in drinking water supplies was released Wednesday and suggests lower exposure levels than recommended by the U.S. Environmental Protection Agency two years ago.

The draft toxicological profile of perfluoroalkyls — manmade chemicals used in the manufacture of nonstick cookware, firefighting foam and more — was released Wednesday by the federal Agency for Toxic Substances and Disease Registry. The study was reportedly blocked by the EPA because of potential public relations issues.

According to the nonprofit Environmental Working Group, the provisional minimal risk level in the report translates to approximately 11 parts per trillion for C8, a substance used for years in the Teflon-manufacturing process at the Washington Works plant in Wood County. The EPA’s health advisory is 70 parts per trillion.

“EPA would allow seven to 10 times more in people’s diets than the ATSDR” proposal, said Olga Naidenko, the Environmental Working Group’s senior science adviser, referring to other chemicals included in the report.

Asked the difference between the numbers, Naidenko said the ones in Wednesday’s report “are based on the more recent science.”

“More research shows that these chemicals are more harmful at lower and lower doses,” she said.

The report examines research of 14 substances that fall under the category of perfluoroalkyls, including C8, also known as perfluorooctanoic acid or PFOA.

The presence of C8 in local water supplies was the subject of a class-action lawsuit whose settlement established a science panel that found probable links between the substance and six medical conditions: kidney cancer, testicular cancer, ulcerative colitis, thyroid disease, preeclampsia/pregnancy-induced hypertension and high cholesterol (hypercholesterolemia).

In 2016, the EPA lowered its lifetime health advisory for exposure to the substance to 70 parts per trillion. Water from the city of Vienna exceeded the new limit and Chemours, the DuPont spinoff that now owns Washington Works, installed a carbon filtration system. C8 is now undetectable in Vienna’s treated water.

The Parkersburg Utility Board, which provides water for Parkersburg and surrounding areas, does not have such a treatment system. Levels of C8 in its treated water have fluctuated but consistently remained below the EPA health advisory.

However, the most recent test showed a concentration of 28 parts per trillion, well below the EPA level, but above the converted provisional risk level in the new report.

Utility board Manager Eric Bennett said Wednesday evening he could not comment on the study until he had a chance to review it.

“I assume EPA will look at the report, and if they feel it’s justified, they will either put out an actual limit on it or lower the health advisory level,” he said.

The EPA level is a “lifetime” health advisory, based on protection for the sensitive populations of fetuses during pregnancy and breast-fed infants. The study’s recommendation for C8 is based on “intermediate” exposure, meaning 15 to 364 days.

The ATSDR report attempts to establish minimal risk levels for the various chemicals. In six categories related to C8 — acute, intermediate and chronic exposure via inhalation and oral means — it finds “insufficient data” for all but one: intermediate oral exposure.

Based on studies involving mice, the provisional MRL is set at 3 x 10(-6) mg/kg/day, which Naidenko said depends in part on an individual’s weight. Using the EPA’s method to translate the numbers for drinking water levels, the recommendations for both C8 and perfluorononanoic acide works out to approximately 11 parts per trillion, she said.

The study indicates exposure could have the most impact on developmental areas, though immunological and liver functions are also sensitive, Naidenko said.

West Virginia Sens. Joe Manchin and Shelley Moore Capito were among members of Congress pushing for the report’s release.

“All West Virginians deserve the comfort of knowing that their drinking water is clean and safe,” Manchin said in a statement. “It is the obligation of the EPA and our government to ensure that the public has as much as information as possible.

“With the release of the report, we can take additional steps to address these issues in West Virginia and continue to pursue a definitive rule that sets maximum limits on these chemicals,” he said.

Capito said the report will help identify potential threats to the health of West Virginia communities.

“I will carefully review these findings and will continue to push for transparency when it comes to the health and safety of those living in our state and in states across the country,” she said in a separate release.

Chemours did not offer a statement on the report Wednesday afternoon.