GERIATRIC BONE LEAD METABOLISM IN A FEMALE NONHUMAN PRIMATE POPULATION

A geriatric rhesus monkey (Macaca mulatta) population, previously expo sed to lead, was investigated using Cd-109 K X-ray fluorescence (K XRF ) to determine whether metabolism of lead in bone was similar to that in human populations. The accumulation rate of lead into the tibia in this group of monkeys was determined to be 0.10-0.13 mu g Pb (g bone m ineral)(-1) (mu g dl(-1) year)(-1), which compares well with human dat a, where the rate has been found to be 0.05-0.10 mu g Pb (g bone miner al)(-1) (mu g dl(-1) year)(-1). In addition, bone lead changes over a 10-month time period were investigated, but no statistically significa nt difference was found. A half-life for lead in ''bone'' was calculat ed by fitting a single exponential model to serial blood lead data; th e mean half-life of lead in bone was found to be 3.0 +/- 1.0 years, Bo th endogenous and exogenous lead exposure were found to be low at the present time, 10 years after cessation of lead intake, It is concluded that rhesus monkeys are an extremely good animal model of human bone lead metabolism and, in addition, that further research is needed to p ro vide a more complete understanding of lead metabolism in geriatric populations. (C) 1997 Academic Press.