High bone matrix turnover predicts blood levels of lead among perimenopausal women.

Skeletal bone is the primary endogenous source of lead in circulating blood, particularly under conditions of accelerated bone turnover and mineral loss, such as pregnancy and postmenopausal osteoporosis. We studied the influence of bone turnover rate on the release of lead from bone in 1225 female farmers from 5 districts in Japan. We collected peripheral blood and urine samples and medical nutritional information, and measured forearm bone mineral density (BMD). We found that blood lead levels in perimenopausal women were highest among all groups studied. Analysis of data for subjects grouped by level of markers of bone metabolism suggested that, in perimenopausal women, blood lead levels were higher in groups with high levels of N-telopeptide cross-linked collagen type I (NTx) and high levels of bone-specific alkaline phosphates (BALP) or osteocalcin (OC) compared with groups with low NTx and low BALP or OC levels. Linear multivariate models showed that markers of bone turnover were significantly positively related to blood lead levels. These results provide evidence that high bone turnover rates increase the release of lead stored in bone into the circulation. It is likely that markers of bone metabolism can be used to predict blood lead levels.