iodide can chelate but is considered a weak ligand and since there are stronger ones available, nobody uses it for that. Has anyone considered the fate of the magnesium atom in chlorophyll when same is exposed to mercurials ? Thermodynamically, it should be favorable for the porphyrin ring of chlorophyll to exchance its Mg for a heavy metal, but I think you have to also look at the size of the hole where the Mg resides to determine what it'd be effective at. We do know that Hg has impact on urinary porphyrin excretion - I think that's a clue in itself. Eat more green stuff - God put natural chelators out there for you all, without them you'd already have been dead. Kale, dandelion, spinach, dark leafy green things are good for you.