The Michigan Department of Environmental Quality says it has collected about five dozen syringes from a St. Clair County channel.
Andrew Shannon of the DEQ's medical waste regulatory program tells the Times Herald of Port Huron the number of syringes is larger than most collections the agency sees.
He tells the newspaper for a story Friday: "Once in a while we will get reports of one or two, but not this amount."
Shannon says diseases such as hepatitis and HIV can be transmitted through such syringes if someone is stuck.
A man who lives nearby found the syringes this week and reported it to the state.
The waste was found in a boat bay where the man stores his boat in Clay Township, about 30 miles east-northeast of Detroit.