DMPS is powerful stuff. I have heard people getting it in an iv, but not using it orally. It has much greater toxicity than DMSA or ALA. I think it is the stuff to use if you are desperate, or the victing of an industrial accident. This website claims DMPS is not even FDA approved.

http://www.dmpsbackfire.com/default.shtml

Even if you can get a physician to use DMPS, I suggest it be used only as a last resort. Some claim it is 10x as toxic as DMSA. I just looked at these websites briefly before. I plan to read them in more detail soon.