Problem. There is evidence of a history of differences in blood lead levels by race/ethnicity and SES, could be due to differences in ambient exposure levels, biology, behaviors, or psychosocial factors. Although blood lead levels have declined, the health effects of lead exposure are still of considerable public health concern, due to its persistence in the environment, the accumulation of, and possible release from bone, and persistent, or progressive health effects associated with lifetime cumulative lead dose.
Methods. 1,140 subjects, ages 50 to 70 years, were randomly selected from 65 neighborhoods in Baltimore, Maryland. 112 women were selected by stratified random sampling by race/ethnicity and VDR fokI genotype to complete BMD measurement. BMD, blood, and bone lead were measured by dual energy X-ray absorptiometry, anodic stripping voltammetry, and 109Cd-induced K-shell X-ray fluorescence, respectively. Multiple-linear regression was used to model the three lead biomarkers. Multilevel analysis was used to evaluate associations with the neighborhood psychosocial hazards scale.
Results. In 1,140 subjects, mean (SD) blood, tibia, and patella lead levels were 3.5 (2.4) μg/dL, 18.9 (12.5) μg/g, and 6.8 (18.1) μg/g, respectively. African-Americans had higher tibia lead levels than whites. Sex modified relations of race/ethnicity, and physical activity with blood lead, and relations of age with tibia lead. Patella lead levels differed by sex, and APOE genotype modified this relation. The NPH scale was positively associated with tibia lead levels. In the sub-sample, BMD was positively associated with tibia lead levels. BMD modified relations of APOE genotype, and Yale energy index with tibia lead, and relation of the index with blood lead.
Conclusions. In this first population-based study of older adults with sociodemographic diversity, African-Americans evidenced a prominent disparity in cumulative retained lead dose. The results suggested a higher turnover rate of lead from patella in aging women despite similar lifetime doses. There was evidence of the influence of the NPH scale influence the kinetics of tibia, and patella lead, independent of individual-level risk factors. In the sub-sample, there was evidence of the influence of BMD, APOE, and VDR genotypes, and physical activity on the kinetics of blood, tibia, and patella lead.