How to Define PFAS

July 1, 2022

Read the full article by Cheryl Hogue (C&EN)

"The name for a family of commercial chemicals usually provides a fairly clear idea of the related compounds within it. An example is organophosphate pesticides. Another is brominated flame retardants.

But the moniker per- and polyfluoroalkyl substances (PFAS) is less distinct. What constitutes this clan of thousands of environmentally persistent and widely used synthetic compounds, including some toxic molecules, depends on a detailed definition.

There’s more than a single definition of PFAS. The one that policy makers use will ultimately determine which fluorinated chemicals are scrutinized for possible regulation.

In the US, environmental and health activists are worried about a PFAS definition that the Environmental Protection Agency rolled out a year ago. It includes far fewer molecules than one crafted by an international panel that included EPA scientists. Meanwhile, the US chemical industry’s largest trade association says both the international panel’s definition and the EPA’s are too broad. Ultimately, Congress may decide which definition federal agencies follow."