A little background: My boy's autistic and I'm using the DAN(Defeat Autism Now) protocol, and in the world of autism, chelation is one of many many options to help our children. Many parents believe that their children displayed autistic characteristics after being injected with the MMR vaccine.
The first step of the protocol is to see if there are any deficiencies ie. vitamin, minerals, amino acids, EFAs etc. Also to see if there are any obvious or not so obvious food allergies. And a hair analysis is done to see if there is toxic overload(mercury, lead and aluminium are the major culprits here).
The persons system is then corrected as much as possible ie. add needed vits, aminos etc; eliminate allergic foods etc.
A test is then done to see if their bodies can withstand chelation ie are they strong enough.
As far as I know the Di-Sulfhydryl(DMSA) is the safest way to chelate(pill wise) and I wouldn't try anything stronger. And remember on days of chelation minerals should be taken after chelation not before or double up on minerals the next day. Chelatory agents not only take out the toxic metals but also the good minerals we need.
If your worried and rightfully so, look into the site evenbetternow, it has an even more gently way of chelating.