MUSCATINE, Iowa (AP) — Officials in an eastern Iowa county have suspended the use of a waste material on gravel roads because of concerns it could be harmful, especially to children. The Muscatine Journal reports that Muscatine County supervisors voted Monday to suspend the use of slag while they wait for further testing on the material. The move comes after an Iowa Public Health Department toxicologist issued a report that said slag, which is a byproduct of steel manufacturing, contains metals at levels that can be harmful.

County Supervisor Nathan Mather says the material hasn’t been used on roads since June. Glenn Hundertmark is the North American environmental manager at Harsco, the industrial company that provides the county with slag. He says there aren’t health or environmental risks tied with the material. Hundertmark requested time to provide additional information.