Tainted drywall mainly came from a Chinese exporter. A small amount of domestic drywall has also been found to have been toxic as well, but it is unclear whether it became toxic after being exposed to the Chinese variety or due to other causes. The possibility also exists that it could have been rebranded upon entry into the US.
Most of the affected drywall came from Chinese gypsum mines. Because gypsum is often in close proximity to many other minerals, some of which are toxic, careful mining is important. Knauf Plasterboard Tianjin Co. Ltd. became aware of the foul odor emanating from the finished drywall. It was determined that the odor was coming from iron disulfide, a naturally-occurring mineral in the Chinese gypsum mine. Knauf ceased operations in that mine in late 2006.
The Chinese Drywall Manufacturing Process
Iron disulfide is heated during the manufacturing process. This heating causes the emitted sulfur to oxidize, which forms highly-soluble sulfur dioxide. This compound remains in the drywall. Sulfur dioxide emits a sulfuric odor under conditions of high heat and humidity and reacts with water vapor. This reaction forms sulfuric acid which corrodes the metals, such as copper and silver, found in many home plumbing and sink fixtures, appliances and other systems.
In addition to sulfur dioxide, the chemical strontium sulfide was also among the irritants found. Gases released from the drywall include hydrogen sulfide, carbon disulfide, and carbonyl sulfide, although none have yet been found to be in high enough concentrations to cause the health effects experienced by many. The guidelines are written for levels of exposure for 8 hours a day in the workplace. More studies are being conducted to determine if the difference in exposure time will change the guidelines for home exposure.
Dickson Home and Building Inspections services the Tampa Bay area for residential and commercial building inspections, to include Chinese drywall inspections. John Dickson is a class “A” certified General Contractor. My Inspector General performs the same services outside the Tampa area. All inspectors are certified general contractors and are well aware of the damage and symptoms that Chinese drywall can create.
Home 
