I am wondering if it still possible to be sold the toxic wallboard from China. How to insure that wallboard subcontractors don't install it?
Buy US made wallboard?
The obvious solution is to make sure the drywall you purchase is made by an American company. The two big brands are USG's "Sheetrock" and National Gypsum's "Gold Bond".
You might find the kind useful as well.
Here is a link that might be useful: News article on identifying Chinese drywall