Metabolism of airborne particulate lead in continuously exposed rats: Effect of penicillamine on mobilization

Abstract

Sprague-Dawley rats of both sexes were exposed to airborne particulate lead at a level of about 20 μg/m3 for periods up to 15 months. Blood lead plateaued at a level of about 26 μg/100 ml within 5 months, as compared to a nearly constant level of 4 μg/100 ml in the controls. On discontinuance of the exposure, the blood lead fell (within 3 months) to a level of about 6 μg/100 ml; treatment with penicillamine (20 mg/kg, twice daily, 5 days per week for 6 weeks) greatly accelerated the rate of decline of this parameter. Urinary and fecal outputs of lead (as micrograms/day) in the treated animals during the exposure period exceeded those in the controls by about 100–300%. There was little increase in tissue lead between the sixth and fifteenth months of exposure; however, in femur the increase during this period was nearly 70%. The level of exposure in these experiments, in terms of micrograms per cubic meter of air far exceeded the yearly mean in most American cities (1–3 μg/m3).