Lead concentrations in cortical and trabecular bones in deceased smelter workers

Abstract

The aim of the study was to compare bone lead concentrations in cortical and trabecular bones in long-term exposed primary copper and lead smelter workers, and to relate the measured concentrations to the previous lead exposure of the workers. Lead concentrations in seven bones (trabecular: sternum, vertebrae, iliac crest, rib; cortical: femur, left forefinger, and temporal bone) were determined by electrothermal atomic absorption spectrometry in 32 male, long-term exposed copper and lead smelter workers, and compared with levels in 10 male occupationally unexposed reference persons. A time-integrated blood lead index (cumulative blood lead index, CBLI) was calculated for each worker. The lead levels in the seven studied bones were all significantly higher in active and retired lead workers as compared with the reference group ( p ⩽ 0.003 ). The highest lead concentrations among the workers were observed in finger bone (median 106 μg/g), followed in order by vertebrae, iliac crest and sternum. The highest quotients between median bone lead concentrations of workers vs. reference group were observed for trabecular bones (sternum 12.3, iliac crest 11.8, rib 8.8 and vertebrae 8.5). In retired workers, strong positive correlations were noted between lead levels in sternum and iliac crest ( r s = 0.91 ; p < 0.001 ) and femur and temporal bone ( r s = 0.88 , p < 0.001 ). Neither CBLI nor exposure-time was related to the bone lead concentrations in any of the studied groups. The findings indicate similarities in the metabolism for bones with the same basic structure. The highest lead concentrations were found in finger bone, which can be used for retrospective exposure evaluations in lead exposed populations, e.g. through XRF-measurements.