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Persistent Pollutants

US EPA yanks toxicity assessment of PFAS contaminant, citing political interference

Agency says scientific integrity of PFBS document was compromised

by Cheryl Hogue
February 10, 2021

Political meddling and a breach of scientific integrity led the US Environmental Protection Agency to reconsider a toxicity assessment for perfluorobutanesulfonic acid (PFBS), the EPA says.

PFBS is part of a family of environmentally persistent chemicals called per- and polyfluoroalkyl substances (PFAS), many of which are toxic. PFBS has been detected widely in drinking water, wastewater, and food packaging, according to the EPA.

Drawing shows the chemical structure of perfluorobutanesulfonic acid.

Invoking a Jan. 27 memo on scientific integrity and evidence-based policymaking from President Joe Biden, the EPA announced Feb. 9 that it was removing the PFBS assessment from its website and reviewing the document.

The move came after EPA scientists scrutinized a package of actions on PFAS, including release of the PFBS assessment, announced on Jan. 19 during the last hours of the Trump administration. The scientists determined that the conclusions on PFBS “were compromised by political interference,” the agency says in a statement.

“Issuing documents, like the PFBS Toxicity Assessment, that include conclusions purporting to reflect science when in fact they are the product of biased political interference undermines the agency’s scientific integrity policy and erodes the trust that the American public has in EPA, the quality of our science, and our ability to protect their health and the environment,” says EPA career scientist Jennifer Orme-Zavaleta. She is the agency’s acting assistant administrator for research and development and acting science adviser.

The assessment had set a safe daily dose for long-term exposure between 0.0003 and 0.001 mg of PFBS per kilogram of body weight per day. This differed from previous EPA toxicity assessments, which set a single value.

“At political direction, the PFBS assessment was changed to provide ranges of values rather than the previously peer-reviewed and vetted reference value,” Orme-Zavaleta says in an emailed response to a C&EN query. “These changes were made after the assessment had completed external peer review and public comment” and following final review by the agency and an interagency group, she says.

Presenting toxicity values as a range is not scientifically sound, she adds, and would create “significant challenges” to EPA regulators attempting to rely on the assessment to set cleanup or drinking water limits.

Giving a range for the PFBS safe daily dose “does not serve the interest of communities. It gives too much discretion to cook the books and calculate less protective safety thresholds,” says Melanie Benesh, legislative attorney for the Environmental Working Group, an advocacy group.

3M introduced PFBS to replace surfactants that were based on one of the first-generation PFAS, perfluorooctanesulfonic acid, and were used for decades in the company’s Scotchgard products. PFBS is used as an industrial surfactant and to make water- and stain-resistant coatings.



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