Minnesota to test air for harmful PFAS pollutants

Minnesota scientists believe that PFAS, the ubiquitous, potentially toxic chemical compounds that have polluted groundwater in just about every corner of the country, are almost certainly in the air as well.

To test that premise, the Minnesota Pollution Control Agency (MPCA) is seeking a federal grant to monitor for airborne PFAS at a handful of sites across the state.

Exactly how much of the chemical is being released into Minnesota's air, and what kind of risk it poses to human health, is unclear. The monitoring project would be the first time the MPCA has tested for the compounds as an air pollutant.

"We like to think about these sorts of things in boxes — with contaminants in air and water, and even fish, all separate," said Summer Streets, an MPCA research scientist. "But that doesn't really reflect our reality. There is no boundary. It's all connected."

For more than half a century, manufacturers such as 3M and DuPont have used perfluoroalkyl and polyfluoroalkyl substances — known as PFAS or sometimes PFCs — in consumer products such as nonstick cookware and Scotchgard, as well as military firefighting foams.

Their ability to shed water and other substances makes them useful in everything from dental floss to textile treatments, cellphone coatings to window panes.

They have been detected in the drinking water, groundwater and soil of hundreds of sites across the country. The compounds were discovered in wells and drinking water in several east metro suburbs near 3M manufacturing facilities starting about 2004. 3M has paid for monitoring, cleanup and bottled water in several of those cities, and in 2018 paid Minnesota $850 million to settle a lawsuit over environmental damage.

But it's not exactly known how PFAS have spread so far and so pervasively. Last year, the MPCA collected hundreds of fish and tested the water from more than 70 lakes and rivers in Minnesota, including some of the state's most remote bodies of water.

Researchers found PFAS chemicals in all of them.

"There's not a single water body that doesn't have at least one PFAS compound in it," Streets said. "There is no place where we find absolutely nothing, and that includes places that have no obvious point source, no discharges and no businesses in the area."

The compounds, Streets said, are very likely coming from the air.

As part of the MPCA testing project, monitors are expected to be set up as soon as this winter in Eagan, near several businesses that are potential users of PFAS, as well as in St. Louis Park, next to a known source of the compounds. A monitor would also be set up in Grand Portage, in an area far from any known PFAS sources.

The findings could help regulators track PFAS from their sources and manufacturers to Minnesota water supplies and guide future decisions for setting safety standards, Streets said.

Even though PFAS compounds have long been known to be harmful pollutants, neither state nor federal regulators have set uniform safety standards for human exposure.

The U.S. Environmental Protection Agency recommends that states and municipalities set a threshold of 70 parts per trillion for two of the most well-known forms of the contaminant, PFOA and PFOS. But many scientists, including those with the U.S. Centers for Disease Control and Prevention, believe the chemicals can be dangerous at much lower concentrations. A report released this year by the CDC found the "minimal risk level" at just 7 to 11 parts per trillion.

Minnesota has set advisory levels for groundwater that are five times higher than that minimal risk level — 35 parts per trillion. Water plants and municipalities are not required to meet those advisory levels for drinking water.

While more states are beginning to test for PFAS in the air, no screening values have yet been set to determine what concentration levels pose a risk, Streets said.