LEAD-INTOXICATION CAUSED BY SKELETAL DISEASE

Background Inorganic lead is accumulated in the skeleton, which harbor s more than 90% of the body burden of lead. If rapidly mobilized this pool may constitute a health risk. However, clear evidence of this the ory has been lacking. History A previously healthy 36-year-old Swedish man with more than 10 years of work-related lead exposure developed h eadache, musculoskeletal pain, and paresthesia of both arms. Two month s after the cessation of exposure, the lead level in his blood (B-Pb) was 5.5 mu mol . l(-1), and treatment with chelating agents was starte d. Shortly after the treatment period, he had an accident causing a fr acture of the right collum femoris. The B-Pb was fairly stable around 1.5 mu mol . l(-1) for about two years after the end of exposure (95th percentile 0.6 mu mol . l(-1) for occupationally unexposed Swedish me n). The examination showed that the patient had high skeletal turnover and clearly reduced bone density, as well as signs of tubular dysfunc tion. He was given the diagnosis idiopathic osteoporosis. His moderate ly raised bone lead concentration (about 20 mu g . g wet weight(-1); n ormal level in Sweden 4 mu g . g(-1)) can only partly explain the rais ed B-Pb, remaining for years after the cessation of exposure. Instead, the main explanation is probably the increased skeletal turnover. Con clusions A combination of a moderately increased bone lead pool and sk eletal disease seems to increase the risk for lead poisoning.