what is the most common chemical used in commercial household rug cleaners?

Answer 1

The basic ingredients of carpet cleaners are perchloroethylene (used in dry cleaning) and naphthalene.

The problems with using rug cleaners of any type are the fumes given off by rug cleaners.
These fumes can cause cancer, damage your liver, and have been known to cause dizziness, sleepiness, nausea, loss of appetite and disorientation.
If you need to use these products, you need to be sure to always "Read the Label First" to know how to properly use these products and for safety information.
Be sure to use these products in well ventilated area and try not to breathe the fumes.

the second site will tell you what to do if someone using a rug cleaner, has an accident.