Occupational determinants of bone and blood lead levels in middle aged and elderly men from the general community: the Normative Aging Study.

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.