Starting EDTA

My 9 year old ASD son has been doing chelation with oral DMSA for a little over a year, Now he is going to be starting EDTA probably this weekend. I'd like some feedback from other parents who have done this. Basically I'd like to hear about changes you saw, good or bad, with your child. I have been wanting to try this for quite some time but we were waiting on lab results from Doctors Data and now we have those. He tested high with Arsenic and Cadium and that really bothers me. We've been doing DAN treatment for almost 2 years and I've seen great results from that.
Any input would be greatly appreciated.