FACTORS INFLUENCING BONE LEAD CONCENTRATION IN A SUBURBAN COMMUNITY ASSESSED BY NONINVASIVE K-X-RAY FLUORESCENCE

Objective.-To determine the influence of demographic, exposure, and me dical factors on the bone lead concentration of subjects with backgrou nd (nonindustrial) environmental lead exposure. Design.-Survey. Settin g.-Suburban residential community. Participants.-A total of 101 subjec ts (49 males, 52 females; aged 11 to 78 years) were recruited from 49 of 123 households geographically located in a suburban residential nei ghborhood unexposed to any major source of industrial lead emissions. Main Outcome Measurements.-Cortical bone lead concentrations in the mi d-shaft of the tibia were noninvasively measured by in vivo K x-ray fl uorescence. Blood lead concentrations were measured by anodic strippin g voltammetry. An administered questionnaire assessed potential source s of lead exposure and medical conditions affecting bone metabolism. R esults.-After the exclusion of one outlier, log-transformed bone lead concentration was highly correlated with age (r=.71; P less-than-or-eq ual-to .0001). Bone lead concentration showed no significant change up to age 20 years, increased with the same slope in men and women betwe en ages 20 and 55 years, and then increased at a faster rate in men ol der than 55 years. In addition to the variables age and sex, the best fitting multiple regression model for bone lead concentration (R2=.66; P less-than-or-equal-to .0001) revealed a positive correlation with t otal pack-years of cigarette smoking and a negative correlation with a history of having nursed an infant for longer than 2 weeks. Blood lea d concentrations of the subjects were low (geometric mean, 0.24 mumol/ L [4.9 mug/dL]) and after log transformation were weakly correlated wi th log-transformed bone lead concentration (r=.23; P=.02). Conclusions .-The age- and sex-related increases in bone lead concentration found by K x-ray fluorescence concur with published postmortem studies of bo ne lead concentration and are consistent with the kinetics of bone tur nover and secular trends in lead exposure. These data help to establis h a reference range for assessing the lead burden of other populations with environmental or occupational lead exposure.