Chinese Drywall Contamination

In the mid-2000's, there was sudden rapid growth in commercial building and residential housing markets within the southeastern US states. When hurricanes - most notably Katrina - wreaked havoc in these areas, in order to rebuild structures quickly builders relied on drywall supplied from China to supplement drywall shortages within the US. At that time, the builders were unaware a drywall contamination problem would silently surface later. Building dwellers have encountered problems with corroding wiring metals (mainly copper) of electrical units due to the conversion of sulfur dioxide found in Chinese Drywall to sulfuric acid. Also residents have experienced numerous breathing problems, associated with off-gassing compounds.

The problem could be widespread, more than to just the southern US. Recent figures show that over 309 million square feet of Chinese Drywall were imported into the US during the housing boom.

The Environmental Protection Agency (EPA) released a report on May 19, 2009 confirming that Chinese drywall does in fact contain sulfur as well as two other organic compounds that do not appear in domestically manufactured drywall. However, the health effects associated with low levels of these compounds have not yet been clearly established.

The CDC reports that the following health symptoms have been reported regarding exposure to Chinese Drywall contaminants:

• Short-term exposure (hours), to low levels: Irritated or itchy skin and eyes, difficulty breathing, persistent cough, runny nose, recurrent headaches, sinus infection, and asthma attacks.
• Chronic exposure (days to weeks), to low levels: In addition to the above symptoms, long-term exposure can result in fatigue, loss of appetite, irritability, and poor memory.

What could be causing the problems with drywall made in China?
Investigations by the US Consumer Product Safety Commission (CPSC) are underway to determine the source of the odors and corrosion, reportedly caused by drywall imported from China.

Drywall is a layer of gypsum-based plaster sandwiched between sheets of paper. The majority of gypsum in drywall from the US comes from mines or quarries. Air sampling studies of volatiles originating from Chinese drywall have identified sulfurous gases, and these emissions appear to worsen with temperature and humidity - the same is not observed with US-made drywall.

Various theories have been proposed as the source of the contamination in Chinese drywall, mainly – the gypsum comes from mines rich in elemental sulfur, or rich in elemental strontium; the mined gypsum contains metal sulfides (like iron pyrite, strontium sulfide); impurities are introduced either during the manufacturing process, or during post-production chemical treatment; also, due to sulfur-generating bacteria, or due to bacteria that attack sulfur-containing compounds. References can be found in the articles linked below. The results of the CPSC federal investigation are expected by year-end 2009.

Contaminants of Interest

• Carbon disulfide
• Carbonyl disulfide
• Hydrogen sulfide
• Sulfur dioxide
• Iron disulfide
• Aldehydes
• Ozone