SUPERIOR, Wis. — Health officials said more than 200 workers tested for lead exposure at a Superior shipyard had elevated levels of lead in their blood.

Wisconsin and Minnesota health departments began a joint investigation last spring after workers at Fraser Shipyards were exposed to lead while retrofitting the Herbert C. Jackson originally built in 1959.

Wisconsin Department of Health Services chief medical officer Jon Mieman said about 73 percent of the 233 workers tested had blood lead poisoning. Mieman says short-term effects may include anemia, headache and fatigue.