A green liquid was seen oozing onto Interstate 696 in a suburb of Detroit on Friday. Portions of the highway were blocked off and officials called in federal agencies to investigate.
It was discovered on Saturday that the liquid was the chemical hexavalent chromium and was leaking from a local business, Michigan State Police said.
Hexavalent chromium is produced during industrial processes like plating. It is known to cause cancer, according to OSHA. The chemical is harmful to the respiratory system, kidneys, liver, skin, and eyes.
The chemical was leaking from the basement of the business and into the ground before going to a drain that emptied out onto the highway. Officials told WDIV-TV that it could take days to safely clean up the chemical.