THE RELATIONSHIP BETWEEN BONE LEAD AND HEMOGLOBIN

Objective.-To determine whether the concentration of lead in bone cons titutes a biological marker that is more sensitive for chronic toxicit y than blood lead levels. Design.-Survey. Setting.-A construction trad e union with members who engage in carpentry, demolition, and other co nstruction activities. Participants.-Members of the construction trade union. Main Outcome Measures.-We measured blood pressure, serum creat inine, hematocrit, and hemoglobin. We measured blood lead by anodic st ripping voltametry and used a cadmium 109 K x-ray fluorescence instrum ent to make in vivo measurements of lead in the tibia (a heavily corti cal bone) and the patella (a heavily trabecular bone). Information was also collected on medical history, smoking, and alcohol ingestion. Re sults.-Bone lead levels in the patella were found to be significantly correlated with a decrease in hemoglobin and hematocrit, even after ad justing for age, blood lead, body mass index, cigarette smoking, and a lcohol ingestion and removing outliers. Blood lead levels were low (me an=0.40 mu mol/L [8.3 mu g/dl]) and were not correlated with either he moglobin or hematocrit. In the final multivariate regression model tha t corrected for measurement error, an increase in patella bone lead le vel from the lowest to highest quintile in this study population (37 m u g/g) was associated with a decrease in hemoglobin and hematocrit of 11 g/L (95% confidence interval [Cl], 2.7 to 19.3 g/L) and 0.03 (95% C l, 0.01 to 0.05), respectively. Conclusion.-We conclude that patella b one lead levels are associated with decreased hematocrit and hemoglobi n levels despite the presence of low blood lead levels. This conclusio n may reflect a subclinical effect of bone lead stores on hematopoiesi s and is the first epidemiological evidence that bone lead may be an i mportant biological marker of ongoing chronic toxicity.