I already did 90+ rounds of cutler chelation for mercury in the past, so I think that mercury isn't the problem anymore. Cutler is right that Iodine isn't a chelating agent but nervertheless Iodine enhances metabolic speed and causes the bones to remodulate, that is the reason why lead come up when there is prolonged supply of iodine.
Look at Holmes et al: "THE EFFECT OF VITAMIN C ON LEAD POISONING" there it is stated that
“Renal excretion of lead depends directly upon the lead compounds circulating at the time in true solution in the blood. . . . The increased excretion (of lead) through use of potassium Iodide has been noted by previous workers, although others have failed to confirm it, chiefly because they confined themselves to the urine while the excretion is mainly in the faeces. The Iodide causes the reappearance of lead in the faeces from which it had been absent.”
So at least it is an investigation to be carefull that Iodine could loosening the tightly bound lead at bone-storagesite.