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Persistent Pollutants

US EPA orders toxicity tests on another PFAS chemical

HFPO is used in the manufacture of fluoropolymers

by Cheryl Hogue
January 5, 2023


The US Environmental Protection Agency has ordered several chemical companies to test hexafluoropropylene oxide (HFPO) for possible adverse health effects.

Chemical structure of hexafluoropropylene oxide

HFPO may present an unreasonable risk of injury to health or the environment, the agency says in a statement explaining the rationale for its Jan. 4 order. The substance could cause toxicity to the nervous system, adverse reproductive effects, and cancer, according to the EPA. In addition, there is insufficient data to determine whether or how breathing HFPO, which is a gas at room temperature, affects human health, the agency adds.

HFPO is part of the family of per- and polyfluoroalkyl substances (PFAS), synthetic chemicals that are highly persistent. Some are toxic. More than 450,000 kg of HFPO are manufactured in the US each year, according to the EPA.

“The information EPA receives under this order will not only improve the Agency’s understanding of human health effects of HFPO, but also the effects of dozens of PFAS that are structurally similar to HFPO,” the agency says in its statement.

Companies named in the order are Chemours, 3M, and both DuPont De Nemours and its predecessor company, E. I. du Pont de Nemours and Co. The EPA says the companies already voluntarily submitted some data on HFPO.

HFPO is used to make fluoropolymers, agrochemicals, and pharmaceuticals, according to the Chemours website. It is one of the substances in the company’s GenX process, which replaced one of the toxic PFAS, perfluorooctanoic acid (PFOA), in the production of fluoropolymers.

The order is the second on PFAS that the EPA has issued under the Toxic Substances Control Act in accordance with the agency’s 2021 strategy for testing PFAS. The first addressed 6:2 fluorotelomer sulfonamide betaine (6:2 FTAB), which is an ingredient in firefighting foams.



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