Background: Few studies of the general population have investigated risk factors for elevated levels of lead in bone in relation to occupation.
Methods: Six hundred and fifty six community-exposed men had their bone and blood lead levels measured (by K-X-ray fluorescence). Based on their occupational histories, participants were categorized into those who worked in white-collar (WC) occupations (59%) or blue-collar (BC) occupations (41%). No subjects had worked in a primary lead industry (e.g., smelting).
Results: In multivariate regression models that adjusted for age, race, education, smoking, alcohol ingestion and retirement status, BC subjects had tibia and patella lead concentrations that were 5.5 (95% CI: 3.2-7.8) and 6.5 (95% CI: 3.1-9.8) microg/g higher than WC subjects, respectively. Interaction terms pairing race with occupational status indicated that in non-white BC subjects, tibia and patella lead levels were higher still by 11.3 (95% CI: -2 to 24.5) and 20.5 (95% CI: 1.2-39.8) microg/g, respectively. Blood lead levels were low for these mostly retired men (mean [SD]: 6.1 [3.9] microg/g) and in multivariate regression models, occupational status was not a significant predictor of blood lead levels; however, an interaction between race and occupational status was also suggested, with non-white BC subjects having blood lead levels that were predicted to be higher by 4.5 (95% CI: 0.3-8.7) microg/dl.
Conclusions: Bone lead levels are higher in the men who worked in BC occupations even if they have not worked in primary lead-exposed occupations. This effect is markedly stronger in non-white BC workers and suggests an interaction between occupational exposures and race/ethnicity with respect to cumulative exposure to lead. A similar interaction was suggested by models of blood lead levels.
Copyright 2002 Wiley-Liss, Inc.