AN ASSESSMENT OF LEAD ABSORPTION FROM SOIL AFFECTED BY SMELTER EMISSIONS

The purpose of this study was to assess the oral bioavailability of le ad in soil collected from a former smelter site in Sandy, Utah, USA. S prague-Dawley rats (approximately 4 weeks of age, 5 of each sex in gro up) were given either soil lead or lead acetate mixed in a purified di et (AIN-93G(TM)) at four different concentrations for 31 consecutive d ays. Food consumption measurements were used to compute mean daily lea d exposures for the soil lead and lead acetate groups. The lead acetat e treatment yielded higher concentrations of lead in the blood and bon e than the soil lead treatment. Mean blood lead values ranged from bel ow the detection limit (3 mu g dL(-1)) to 27.25 mu g lead dL(-1) for t he lead acetate groups at dose levels of 0.10-2.91 mg lead kg body wei gh(-1) and from below the detection limit to 8.8 mu g lead dL(-1) for the soil lead groups at doses of 0.11-3.43 mg lead kg body weigh(-1). At these same doses, mean bone values ranged from 0.52 to 26.92 mu g l ead g(-1) for the lead acetate groups and from 0.64 to 13.1 mu g lead g(-1) for the soil lead groups. Relative per cent bioavailability was estimated by modelling the dose-blood concentration curves for the lea d acetate treatment and the dosed soil lead treatment, and then compar ing doses that produce an equivalent blood lead concentration. The rat io of the doses of lead acetate and soil lead that produced the same t issue response (i.e., concentration) provided an index of relative bio availability. For lead, the bioavailability of soil lead relative to l ead acetate was 41% at a blood concentration of 6 mu g lead dL(-1).