Ten-year follow-up of blood lead levels with medical removal protection of shipyard workers

This cases report compared the short-term changes of BLL with medical removal intervention and follow-up the long-term changes of BLL afterward. During a physical examination in October 1992, a 44-year old shipyard welder was discovered to have a blood lead level (BLL) of 54.1 μg/dl. It was recommended that the shipyard remove this worker from his workplace. In 1993 the BLLs checked for this worker were 36.7 μg/dl in March and 32.0 μg/dl in April. After six months of medical removal, he returned to initial welding work. In 2002, we collected two blood samples from this worker for analysis in May and October. The results were 30.4 μg/dl and 31.6 μg/dl, respectively. Meanwhile, two other welding workers (case 2 and case 3) with BLLs over 40 μg/dl in the survey conducted at the same shipyard in 1992. It took 4 yr to let BLLs downed to less than 40 μg/dl. However, after the blood lead concentration drops to below 40 μg/dl, 10 yr long-term observation indicates that BLLs reduction level off and do not continue to go down in these three cases.