Michigan PFAS by the numbers: How much is unsafe?


Industrial chemicals known as PFAS have been linked to serious health risks. But nobody agrees on how much is unsafe.

The federal government has yet to develop a nationwide standard for PFAS in drinking water, and few states have crafted regulations of their own. Those that have — including New Jersey, Vermont and Minnesota — all have different standards.

And a recent draft report from the U.S. Centers for Disease Control suggests PFAS could be risky at far lower levels that previously believed.

Confused? You’re not alone.

“It’s really no wonder that the average American is driven to wonder whether their drinking water is safe,” Lisa Daniels, director of Pennsylvania’s Bureau of State Drinking Water and president of the Association of State Drinking Water Administrators, told a U.S. House committee this month at a hearing probing PFAS concerns.

Here’s a primer on all the numbers related to PFAS –  shorthand for per- and polyfluoroalkyl substances –  and why they matter.

But first, where did PFAS come from?

Because they can reduce friction, types of PFAS have been used to manufacture everything from Teflon and Scotchgard water repellent to firefighting foam. U.S. manufacturers have largely phased out types of PFAS that are more problematic, but those chemicals are still used internationally to make products that may be imported.

How are PFAS hazardous?

Research is still evolving. The two most studied types of PFAS are called PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate).  The most consistent findings of exposed populations have linked the chemicals to low birth weights, immune system troubles, thyroid problems and cancer, according to the EPA.

How much do the feds say is too much PFAS?

The EPA has no drinking water standard for PFAS. That means the agency has no legal leverage to force a water system to address contamination. In 2016, however, the agency set a health advisory level: 70 parts per trillion for combined PFOA and PFOS over a lifetime. (Think of one part per trillion as a grain of sand in a swimming pool.)  Exposure above the health advisory threshold is seen as a health risk, but the standard is unenforceable.

In June, however, another federal agency offered different guidance.

draft report from the Agency for Toxic Substances and Disease Registry, part of the Centers for Disease Control, produced a “minimal risk level” far below the EPA threshold: 7 parts per trillion for PFOS and 11 parts per trillion for PFOA.

What do states say?

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