DETROIT — Eight people were killed after tornadoes tore through parts of Michigan and Oklahoma late last week, leaving survivors facing immediate and long-term health risks.

An EF3 twister with winds exceeding 150 mph was reported near southern Michigan’s Union City on Friday night, where three people were killed and at least a dozen others were injured. A fatality occurred in nearby Cass County after a 12-year-old boy who had been injured by another tornado died at a hospital.

In Oklahoma, two people died when a tornado hit a home near Beggs, south of Tulsa, and at least two others were hospitalized.…