Hi Bex. I don't think this stuff is a dye and likewise mine is sometimes grey. I find it hard to believe it's dirt too. I can scrape loads of it off once my body temporature gets to a certain level. Could it be metal deposits perhaps?

I know i have to do the ALA eventually and i'm not looking forward to it. However six months ago i couldn't even take DMSA and now i can easily do a round of 25mcgs.