Hi Valentin, you are probably well aware that the moderators in the cutler groups strongly encourage people to start with DMSA or preferably DMPS, not with ALA. I always encourage the sickest members to start with low dose (5mg or less) DMPS.
I also encourage the sickest members to start with low doses of supporting supplements especially antioxidants and then work up to normal doses.
I also encourage them ad nausaum to get adrenal cortex support if they have relevant symptoms.
So many people who are sick with a heavy metal problem benefit from adrenal cortex support.
There are plenty of "chelation cowboys" as I refer to them, who think they can start with generous doses of chelators--or chlorella, cilantro, green smoothies, NAC, glutathione-- without generous amounts of antioxidants and other important supporting supplements. There are plenty of stories where such people had setbacks and took months to bounce back.
Fortunately there are also plenty of reports from those who made a mistake, later recovered and got nice gains, a close female friend is one such person, so is someone in my extended circle of friends.