SUPERIOR, Wis. (AP) — Health officials say 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 Public Radio reports Wisconsin Department of Health Services chief medical officer Jon Mieman says about 73 percent of the 233 workers tested had blood lead poisoning. Mieman says short-term effects may include anemia, headache and fatigue.

Fraser said earlier this month that it had agreed to pay $700,000 to settle a fine from the U.S. Occupational Safety and Health Administration to improve worker safety. Fraser did not admit fault or liability related to the lead exposure.