Jun 23, 2021

It’s raining ‘forever chemicals’ in the Great Lakes - Scientists found high levels of PFAS in raindrops.

A team of U.S. and Canadian scientists analyzed rainfall at six sites across the Great Lakes region and found high levels of per- and polyfluoroalkyl substances, or PFAS, at all the sites, including, surprisingly, rural Michigan. The rainwater samples contained PFAS levels between 100 to 400 parts per trillion (ppt). For comparison, the U.S. Environmental Protection Agency's "safe" limit for drinking water — not rainwater — is 70 ppt.

The findings highlight the ubiquitous nature of PFAS chemicals, man-made substances used in common household products because of their water-, oil-, and grease-resistant qualities. Firefighting foam is also a main source of PFAS. Commonly referred to as "forever chemicals," their legacy can be found everywhere — in soil, groundwater, lakes, oceans, and now, even the rain.

"All of these products that we use in our everyday life are treated with PFAS," Marta Venier, an environmental chemist at Indiana University and the principal investigator for the research, told Grist. "So every time we use them, there is either dust or air where these chemicals are released."

PFAS chemicals are transported through the air and then deposited via precipitation into the environment, where it accumulates, can be ingested by wildlife, and can wind up in the human body. Studies indicate that exposure to PFAS chemicals can cause reproductive, liver, kidney, and immunological damage in laboratory animals. It's also a possible carcinogen — two PFAS chemicals have been shown to cause tumors in animal studies.

The new research was conducted by the Integrated Atmospheric Deposition Network, a monitoring program funded by the U.S. EPA's Great Lakes National Program Office, and managed by Indiana University.  

Beginning last August, scientists collected ambient air and rainwater samples for 38 different PFAS compounds from six sites across the Great Lakes region: Cleveland, Ohio, Chicago, Illinois, Sturgeon Point, New York, Point Petre in Ontario, Canada, and Sleeping Bear Dunes and Eagle Harbor, both in Michigan. Both the rural and urban sites' rainwater showed high levels of PFAS contamination.

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