Chinese Drywall

Chinese Drywall is drywall imported between 2004 and 2006 from certain areas in China and can release sulfur-like odorous components. These compounds can corrode air conditioning coils and other copper-bearing materials, causing them to be replaced repeatedly. It has been determined that the problem is related to presence of iron disulfide (FeS2 pyrite). Hydrogen sulfide (H2S), carbonyl sulfide, sulfur dioxide (SO2), and carbon disulfide (CS2) are also suspected as culprits. There have been reports that large quantities of drywall produced in China were kept on sea barges for months awaiting permission for importation to the USA. This drywall has a higher than typical density and a higher propensity to off-gas sulfur compounds.

Drywall is usually made of gypsum (hydrated calcium sulfate). Therefore, sulfur is one of the main components. All drywall has sulfur in its elemental composition; therefore the odor is not explained by an analysis of the total sulfur content.

The extent of the indoor air quality issues related to this is still unclear. EPA is currently investigating the severity of the problem. However, it is well known that exposure to sulfur compounds can create irritation and breathing disorders.

Visual identification is almost impossible as the manufacture’s stamp is on the backside (non-visible side) or not stamped at all. In some cases, the drywall is marked with a US manufacture’s stamp. Also, not all drywall in a building could be affected which makes detection more difficult.

The approach for the analysis of drywall samples is diverse. The possible avenues are as follows:

1. Analysis of the drywall samples for presence of iron and Fe2S by X-ray Fluorescence, X-ray diffraction, or light microscopy.

2. Analysis for presence of Volatile Organic Compounds (VOCs) and H2S using an environmental chamber.

3. Copper corrosion test can be performed to identify and confirm the presence of substandard drywall (exposure of fresh copper coupons to subsamples of the odorous drywall in presence of humidity).

4. Sulfur odors may also be produced when anaerobic bacteria utilize certain molecules for growth. Therefore, endotoxin analysis for gram negative bacterial contamination and anaerobic plate count may be recommended.

Testing labs such as EMSL have the expertise to perform such tests on drywall samples.