Answer by Steven Fowkes:
The primary detoxification mechanism for mercury is combination with reduced sulfur. This takes place in all tissues and especially in the liver, where the glutathione-bound mercury (GS-Hg-SG) is dumped into the bile for excretion into the gut. The body converts ionic mercury, metallic mercury and organic mercury into glutathione-bound mercury, a small amount of which can be excreted through the kidneys into the urine, but most of which is excreted in bile. The kidney is particularly sensitive to mercury, so urinary excretion is necessarily constrained.
But bile-excreted mercury is not actually removed. Yet. It must pass down the full length of the intestine and colon before it is removed. And this is significantly problematic because glutathione-bound mercury is particularly toxic to single-cell microbes, and they detoxify it by converting it into methyl mercury, which efficiently absorbs back into the blood stream and even crosses the blood-brain barrier. So the detoxed-form of mercury is recycled into the more toxic form during its transit down the GI tract. This is a loop in which mercury can become trapped in the human body.
In idiopathic dilated cardiomyopathy, there is a failure of cellular or tissue-level mercury excretion of glutathione-bound mercury. In one 17-year-old male teenager, glutathione-bound mercury accumulated to almost 0.1% (wet weight!) before he suddenly died on the track field. This mercury accumulation in IDC is (1) limited to the heart and was not found in other muscles or other organs, and (2) shows how effective glutathione is at detoxifying mercury.
If anybody knows the mechanism of this failure in IDC, please post.