Correlates of bone and blood lead levels in carpenters

In the course of a health screening for construction carpenters, 127 subjects underwent blood lead testing, administration of detailed questionnaires, and in vivo measurement of bone lead levels with a 109Cd K-X-ray fluorescence (K-XRF) instrument. The mean age of subjects was 48.5 (SD = 9.8) years. Blood lead levels were low, with a mean of 8.2 (SD = 4.0) micrograms/dl. Bone lead levels had means of 9.8 (SD = 9.3) micrograms/g bone mineral for the tibia and 14.0 (SD = 13.8) micrograms/g bone mineral for the patella (which consist primarily of cortical bone and trabecular bone, respectively). In multivariate regression models, age was the dominant predictor of both tibia and patella bone lead, with years since last worked and welding/brazing contributing an additional small amount of influence over tibia bone lead, and carpet laying, paint stripping, and regular exercise contributing an additional small amount of influence over patella bone lead. Demolition, carpet laying, and alcohol ingestion were significant predictors of blood lead. We conclude that age is the most important predictor of bone lead levels among workers with intermittent exposures to lead; in addition, K-XRF is useful in generating hypotheses on additional factors that may influence lead burden.