出版社：National Institute of Occupational Safety and Health
摘要：Recent data indicate that non-chelatable lead is converted to the che-latable form in the 24 h following intravenous administration of calcium disodium ethylenediamine tetraacetate (CaEDTA). To refine our previous model of the kinetics of lead mobilization in the light of those data, we simulated the daily mobilization yield of lead, zinc and copper in urine by CaEDTA and the sponta-neous urinary excretion of these metals during a 4-day course of intermittent CaEDTA injection as a function of the body burden of the chelatable metal (A), the proportion of the mobilization yield to A (k), the proportion of the sponta-neous urinary excretion to A(β), and the proportion of the chelatable metal con-verted from non-chelatable metal during 24 h following CaEDTA injection (a) to A (α). The values of A, a, k, β and α for each metal were calculated as a solution of the functional equation. We estimated that the body burden of chelatable lead ranged from 2.3 to 9.5 mg (mean 5.5 mg) in ten metal workers, employed on average for 13 years, with the whole blood lead concentrations of 39-64 (mean 49) μg/dl. Similarly, the body burden of chelatable zinc ranged from 0.2 to 16.6 (mean 0.9) g; and that of chelatable copper from 36 to 192 (mean 102) μg. The body burdens of chelatable lead and zinc thus estimated were significantly correlated with the whole blood lead and zinc concentrations. The 24 h mobilization yield of each metal in urine following administration of CaEDTA was approximately 39% of the chelatable body burden for lead, 0.1% for zinc and 33% for copper; 24 h spontaneous urinary excretions were approximately 2.5, 0.01 and 20% of the body burdens, respectively. An amount of non-chelatable lead corresponding to 21% of the body burden of chelatable lead was assumed to be converted from the nonchelatable to the chelatable form during the 24 h after CaEDTA injection; conversion rates for zinc and copper were almost negligible.
关键词：Lead;Zinc;Copper;Body burden;Chelatable metal;Non-chelatable metal;Mobilization test;CaEDTA;Man;Kinetic study
