DETERMINANTS OF BONE AND BLOOD LEAD LEVELS AMONG COMMUNITY-EXPOSED MIDDLE-AGED TO ELDERLY MEN - THE NORMATIVE AGING STUDY

Levels of lead in bone serve as a dosimeter for cumulative exposure to lead; moreover, lead in bone may serve as an internal source of circu lating lead many years after environmental exposure has ceased, The au thors measured lead in blood and used a K-x-ray fluorescence instrumen t to measure lead in the tibia (cortical) and patella (trabecular) bon es in a cross-sectional survey of 719 middle-aged to elderly male part icipants in the Normative Aging Study who were without unusual occupat ional exposures to lead and who were healthy when enrolled in 1962-196 5, Blood lead levels ranged from <1 to 27.9 mu g/dl, with a geometric mean of 5.7 mu g/dl. Tibia and patella lead level ranges (geometric me ans) were <1-51 (20.8) mu g/g and 3-77 (29.8) mu g/g, respectively, In backwards elimination multivariate regression models that considered age, race, education, retirement status, measures of both current and cumulative smoking, and alcohol consumption, the factors that remained significantly related to higher levels of both tibia and patella lead were higher age and measures of cumulative smoking, and lower levels of education, In the final model predicting blood lead that began with these same covariates and also included tibia and patella lead, the f actor that accounted for the dominant portion of the variance in blood lead was patella lead, After adjustment for measurement error, a rise in patella lead from the median of the lowest to the median of the hi ghest quintiles (13-56 mu g/g) corresponded to a rise in blood lead of 4.3 mu g/dl. The authors conclude that bone lead levels are substanti al and comprise the major source of circulating lead in these men.