Intravenous infusion of CaEDTA was given to 45 Japanese adults without occupa-tional exposure to lead for 1 hr in a dosage of 20 mg/kg body weight in 250 ml of 5% glucose solution. The urinary excretion of lead was estimated for 24 hr before, and for 2 hr and 24 hr after the administration. The least variation of the lead content was recognized in the 24 hr urinary excretion after the injection of CaEDTA. No sexual difference was noted in the creatinine-corrected lead concentration.
By multiple linear regression and correlation analyses, age was found to be sig-nificant in determining positively the lead level mobilized in 24 hr urine samples. Height was significant in determining positively the spontaneous 24 hr urinary lead excretion.
Certain significant correlations existed among lead in blood, ALA-D in erythrocyte, δ-ALA in urine, coproporphyrin in urine, lead in urine and lead mobilized by CaEDTA.
The existence of "active" body burden of lead was suggested in human subjects under usual urban condition where the total ambient lead averaged 1.7 μg/m
3 of air.
Based on a few assumptions, it was calculated that about 3 μg of lead was retained on average per day by a Japanese adult; daily retention of lead by Japanese adults was formularized, i.e., Pb (μg)=K×daily creatinine excretion (g), where K is 1.77 in men and 2.73, women.
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