The big question, do I have the defective Drywall? 

Follow this link to a very clever way of doing a test for yourself in your own home.  Ecotech 

There are labs that specialize on testing levels of certain elements as seen below.  This device has the ability to tell you exactly what your drywall is made of.  Refer to Drywall science brochure .  The lab we use is

Strontium (Sr 38)Strontium is a soft, silver-yellow, alkaline-earth metal. It has three allotropic crystalline forms and in its physical and chemical properties it is similar to calcium and barium. Strontium reacts vigorously with water and quickly tarnishes in air, so it must be stored out of contact with air and water. Due to its extreme reactivity to air, this element always naturally occurs combined with other elements and compounds. Finely powdered strontium metal will ignite spontaneously in air to produce both strontium oxide and strontium nitride.

Sample test result.  This home happened to have the worst levels of Strontium we have seen to date.

This test is NOT a certified test.  If you require a "Certified Test" you can use   EMSL Analytical, Inc.  They are a certified lab that will test your drywall and send a certified report.