Some drywall that was imported from China has caused problems with odors and corrosion in homes especially in the humid parts of the U.S. The cause of the problem appears to be the presence of sulfur, possibly in the form of iron pyrite (FeS2) in the gypsum from which the drywall is made. Some chemical reaction within the drywall apparently occurs that allows the release of volatile sulfur compounds such as hydrogen sulfide.

The Environmental Protection Agency has analyzed 2 samples of this problem drywall and compared results to 4 samples of drywall made in the US. Sulfur was detected at 83 parts per millions (ppm) and 119 ppm in the Chinese drywall samples. Sulfur was not detected in the four US manufactured drywall samples. Strontium was detected in all the drywall samples, but at higher concentrations in the Chinese product (2,570 ppm and 2,670 ppm versus 244ppm to 1130ppm). Iron concentrations were similar in the two types of drywall, and no acid soluble sulfi des were detected in any of the samples. Finally, propanoic acid, 2-methyl-, 2,2-dimethyl- 1- (2-hydroxy-1-methylethyl) propyl ester at estimated concentrations of 58 ppm and 92 ppm, and propanoic acid, 2-methyl-, 3-hydroxy-2,4,4-trimethylpentyl ester at estimated concentrations of 50 ppm and 84 ppm were detected only in the Chinese drywall. These compounds are associated with Acrylic paints. Other laboratories have detected elemental sulfur as well as sulfi des (including pyrite). The actual chemistry involved remains unclear.

Not all Chinese drywall has caused problems. The occurrence of odors and corrosion appears to be associated with elevated temperature and humidity. It is interesting to note that dry sulfur is odorless, but the presence of water, even as high humidity, can cause the release of very small concentrations of hydrogen sulfi de. Another hypothesis involves the development of anaerobic conditions within the drywall related to accumulation of water, and the action of sulfur and iron reducing bacteria.

The Consumer Products Safety Commission is conducting a study of health effects related to exposure to Chinese drywall. However, according to the Virginia Department of Health, it appears that concentrations of the volatile sulfur compounds are very low and are unlikely to cause serious or chronic health effects.

A number of laboratories offer tests that can be performed on drywall samples, some of which may confi rm the presence of sulfur and the release of corrosive gasses. Tests are also offered for iron content and endotoxin, which are less specifi c since all drywall have some iron and, if wet, most will contain endotoxin.

However, there is generally no need to use laboratory tests to determine whether or not problem drywall is present in a building. A good on-site inspection, which should always be the fi rst step in any indoor air quality investigation, is the best and least expensive approach. Both the Florida Department of Health (Floridashealth.com) and the Virginia Department of health have good step-bystep onsite inspection guides for determining whether or not you have this drywall problem. These steps involve recognition of characteristic odors, the presence of black oxidation on copper pipes, and early failure of air conditioning cooling coils. The presence of defective imported drywall cannot be determined by “testing” the air in the home according to the Florida Attorney General. Air sampling is not useful due to the very low concentrations of the volatiles that cause the problems.

Remediation involves removal of the drywall. Painting, ozone treatment, and chlorine dioxide treatments have been tried, but do not provide a long-term solution. In fact, the use of oxidizing agents may make the problem worse.

Finally, it is important to remember that many people posting information about the Chinese drywall problem on the internet are not experts in either health or chemistry. If you have questions in these areas, I would suggest using the USEPA and the CPSC websites (USEPA.gov; CPSC.gov). Both of these agencies are actively engaged in research on this problem. Chemical and Engineering News, a journal of the American Chemical Society, has a helpful review (MAY 4, 2009 VOLUME 87, NUMBER 18 PP. 50-51)

Dr. Harriet Burge, Director of Aerobiology and Research and Development and Chair of EMLab P&K’s™ Scientifi c Advisory Board. Widely considered the leading expert in IAQ, Dr. Burge pioneered the fi eld more than 30 years ago. She has served as a member of three National Academy of Sciences committees for IAQ, including as Vice- Chair of the Committee on the Health Effects of Indoor Allergens.

To submit a question to Dr. Burge, write to her by e-mail at This e-mail address is being protected from spambots. You need JavaScript enabled to view it . All questions posed to Burge will receive a reply, although space limitations prevent us from publishing them all. By submitting a question, you agree to have your question and its answer published in a future edition of IE Connections.

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