I looked and looked and the closest I could find was " Electrolytes are essential for proper pH control and elimination of any toxic substance." found on cleanse.net
If you notice in the article, they are referring to "toxic substances" and not THC metabolites. THC is non-toxic, so therefore its erroneous to categorize THC as a toxic substance.
Anyone who considers THC a toxic substance might as well sign up for Anslingers goon squad at their local police station and start calling marijuana an epidemic that is killing America.