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Conversion rate of non‐chelatable to chelatable lead after CaEDTA injection: A kinetic study in two lead workers
Author(s) -
Arak Shunichi,
Murata Katsuyuki,
Yokoyama Kazuhito,
Aono Hiroshi,
Yanagihara Susumu,
Ushio Koichi
Publication year - 1983
Publication title -
journal of applied toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.784
H-Index - 87
eISSN - 1099-1263
pISSN - 0260-437X
DOI - 10.1002/jat.2550030102
Subject(s) - chemistry , calcium , lead (geology) , geology , organic chemistry , geomorphology
Diminution rate of body burden of chelatable lead (CPb) after injection of calcium disodium ethylenediamine tetraacetate (CaEDTA) was estimated at between 0.7 and 0.4% per week in two lead workers after termination of lead exposure. Hence, alteration in body burden of CPb during the week after a single injection of CaEDTA was simulated by two different equations. The first equation was (1 + α−1.3β) 6 (1–1.03 k + α) A = 0.993 A or 0.996 A , where A = body burden of CPb just before CaEDTA injection; α = proportion of CPb converted from non‐chelatable lead (NPb) to A during the 24 h after CaEDTA injection; k = proportion of 24‐h mobilization yield of lead by CaEDTA to A ; and β = proportion of 24‐h spontaneous urinary lead excretion to A . This equation was based on the assumption that the amount of lead converted to CPb during 24 h was proportional to the initial level of CPb. The second equation, i.e. (1–1.03 k ) (1–1.3β) 6 A + {(1–1.3β) 6 + (1–1.3β) 5 + … + (1–1.3β) + 1} α A = 0.996 A or 0.996 A , assumed that the amount of lead converted to CPb during 24 h was nearly constant during a week after CaEDTA injection. The conversion rate (α) was obtained as a solution of each equation after determination of k and β according to our model. It was estimated that the amount of lead corresponding to 2% of body burden of CPb, i.e. 0.23 mg and 0.35 mg, was converted from NPb to CPb during the 24 h after CaEDTA injection in the two lead workers with blood lead concentrations of 44 μg per 100 g and 61 μg per 100 g, respectively. A previous model for estimating body burden of CPb from mobilization yield of lead by CaEDTA was amended in the light of this estimation.