University of Minnesota researchers study environmental impacts of tear gas used during Operation Metro Surge

Throughout Operation Metro Surge, tear gas was used at several standoffs across the Twin Cities metro. A team of researchers says that substance could have left heavy metals in the soil.

They're sites and scenes that an assistant University of Minnesota geography professor says could have long-term health effects. 

"The contaminants from that tear gas doesn't just go away. There's research to suggest it sticks around in the environment, but we don't have a lot of clarity about how it moves through the environment," Rebecca Walker, the lead researcher for the project, said.

Walker and nearly 10 other undergraduate Gophers are working to find answers.

"We started collecting snow samples, and after there were known tear gas events, we'd go out as researchers, scientists and collect snow samples," Walker said.

It's a collaboration with other researchers from the Minneapolis-St. Paul Metropolitan Area Long Term Ecological Research Program, who all study how urban stressors affect our environment.

Walker said they found a high concentration of heavy metals around sites where a lot of tear gas was used, like near the Renee Good and Alex Pretti memorials.

WCCO cameras captured footage from the scene after an ICE agent shot and killed Good on Jan. 7, and moments after a protester threw snow at federal agents on Jan. 24, when Alex Pretti was shot and killed.

Researchers say those sites are two of 30 sites across the Twin Cities that saw tear gas get deployed during Operation Metro Surge. Researchers collected snow samples from nine tear gas sites.

"We don't want to be alarmists; we don't want people to feel unsafe. The goal of the study is the opposite," said Walker, adding it's to educate. "Wash your hands after gardening, washing your veggies really well, it's going to be OK."

So far they haven't found anything of note in soil tests, but they're continuing to look. 

The Minnesota Pollution Control Agency said what they found in snow samples is concerning.