I did the DMSA challenge test...and felt fine....you take a 300mg dose...early in the morning,......you empty your bladder first thing in the morning....than take a 300 mg dose of dmsa(which isn't that high)...wait 20 minutes...than pee into the same container for the next 12 or 24 hrs.....shake the container for 2 minutes to make sure the urine is all combined...than send a sample of the urine to the lab.....I used a lab in chicago...they will check all your metals, and send you results........just so you know....my levels were high....yet my hair analysis showed no mercury(because my body was storing it)...So I believe that the hair tests are crap...but thats just my opinion....Sandra P