Cd-109 K x ray fluorescence measurements of tibial lead content in young adults exposed to lead in early childhood

Objectives-Tibia lead measurements were performed in a population of 19-29 year old people who had been highly exposed to lead in childhood to find wh ether lead had persisted in the bone matrix until adulthood. Methods-Cd-109 K x ray fluorescence was used to measure the tibia lead conc entrations of 262 exposed subjects and 268 age and sex matched controls. Qu estionnaire data allowed a years of residence index to be calculated for ex posed subjects. A cumulative blood lead index was calculated from the time weighted integration of available data of blood lead. Results-The mean (SEM) difference between exposed and control men was 4.51 (0.35) mu g Pb/g bone mineral, and between exposed and control women was 3. 94 (0.61) mu g Pb/g bone mineral. Grouped mean bone lead concentrations of exposed subjects were predicted best by age. When exposed and control subje cts' data were combined, grouped mean bone lead concentrations were predict ed best by cumulative blood lead index. The years of residence index was ne ither a good predictor of bone lead concentrations for exposed subjects nor for exposed and control subjects combined. Finally, exposed subjects had i ncreased current blood lead concentrations that correlated significantly wi th bone lead values. Conclusion-Bone lead concentrations of exposed subjects were significantly increased compared with those of control subjects. Lead from exposure in ea rly childhood had persisted in the bone matrix until adulthood. Exposed sub jects had increased blood lead concentrations compared with controls. Some nf this exposure could be related to ongoing exposure. However, some of the increase in blood lead concentration in adult exposed subjects seemed to b e a result of endogenous exposure from increased bone lead stores. The endo genous exposure relation found for men was consistent with reported data, b ut the relation found for women was significantly lower. Further research i s needed to find whether the observed differences are due to sex, or pregna ncy and lactation.