Read the full story at MPR News.
About a decade ago, Minnesota Department of Health researchers began testing samples of drinking water in cities where firefighters had used fire suppression foam during training exercises, usually near airports and military bases. They wanted to know if chemicals from the firefighting foam had made it into the water supply.
One of those cities was Bemidji: Its wells are next to the airport, where firefighters had used the aqueous film-forming foam for decades.
At first, it looked as though Bemidji was in the clear. There were trace amounts of chemicals from the firefighting foam in the city’s wells, but the concentrations were within the limits of what the state health department at the time considered safe.
Over the next few years, two things changed: Researchers got better at detecting the chemicals, broadly known as perfluoroalkyl and polyfluoroalkyl substances — or PFAS. And the level of PFAS that health officials considered safe got a lot lower.