FDA says chemical replacements for PFOA, PFOS more toxic than thought

The chemical structure of 6:2 FTOH (Illustration: ChemSpider)

In 2006, when 3M and DuPont, under legal and regulatory pressure, began phasing out their production of two types of perfluorinated compounds — PFOA and PFOS — the companies had a backup plan: By reducing the number of fluorinated carbon molecules from eight to six or fewer, they could produce new chemicals that would ostensibly be safer than their longer carbon-chain counterparts.

GenX, for example, is a short-chain perfluorinated compound.

But two new FDA studies show that theory isn’t true. The results were recently published in peer-reviewed, independent journals Toxicology and Applied Pharmacology and Food and Chemical Toxicology The Environmental Working Group announced the results of the studies.

The compound in question, 6:2 FTOH is widespread in the environment. It is present in fast food packaging, stain- and water-resistant consumer products, fire-fighting foam — even nap mats at child-care centers..  The general population is exposed to the compound by inhaling it, such as in indoor dust, and eating food packaged in materials containing the compound. 

FDA researchers found that 6:2 FTOH is toxic. It builds up in the liver and fatty tissues of rats, persisting for roughly the equivalent of a year in humans.

These findings are a departure from previous research, including some paid for by the fluorochemical industry, which determined the toxicity of 6:2 FTOH using studies of another short-chain compound, perfluorohexanoic acid, or PFHxA for short. Based on those findings, the industry concluded that PFHxA and other short-chain compounds were not toxic.

It turns out those studies were flawed.

“Our analysis demonstrates that 6:2 FTOH is significantly more toxic than PFHxA,” the FDA researchers wrote. They added that using toxicological studies of PFHxA to assess 6:2 FTOH exposure “may significantly underestimate human health risk.”

Since 2008, the FDA has approved and registered 11 substances on its Inventory of Effective Food Contact Substance Notifications; nine of these substances were plastics based on 6:2 FTOH, according to EWG. Chemours is among the companies that received federal approval to manufacture the compounds.

The chemical industry has produced at least 5,000 types of PFAS. Many public health and environmental advocates and experts have asked the EPA to regulate all PFAS as a class because of their similar toxic effects. But the industry has repeatedly countered that toxicity data, which is limited and primarily conducted by the chemical companies themselves, doesn’t warrant such a broad classification.

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