I've heard numerous warnings on it. Because we do not know the exact mechanism of action and therapeutic dose.
With chelators, if you give a large dose at a time, it mobilizes a ton of mercury and other metals, and could overwhelm the body's detox pathways. Resulting in the unexcreted, but freed, metals redistributing in the body, with more going into the brain than before.
Alpha lipoic acid is also "natural" and a potent chelator. It needs to be taken on a schedule around the clock to prevent redistribution to brain.