To evaluate the effects of calcium disodium ethylenediamine tetraacetate (CaEDTA) on the behavior of 8 heavy metals in human urine and blood, CaEDTA was administered for 1 h by intravenous injection to 18 male metal foundry workers, whose blood lead concentrations (PbB) were between 16 and 59 (mean 34) mug/ dl. Significant increases were found in urinary excretion of manganese, chromium, lead, zinc, and copper after the start of CaEDTA injection. Urinary chromium excretion reached a maximal level within 1 h after the start of injection, while urinary manganese, lead, and zinc excretion reached their highest concentrations between 1 and 2 h. Urinary copper excretion reached the highest level between 2 and 4 h. The rapid increases in urinary excretion of five metals were different from the ''circadian rhythms," which are the normal, daily variations in renal glomerular filtration, reabsorption, and excretory mechanisms. Plasma lead concentrations were highest 1.5 h after the start of the 1-h injection, while plasma zinc concentration became lowest 5 h after the start of CaEDTA injection. Data suggest that manganese and chromium absorbed in human tissues might be mobilized by CaEDTA.