Late last month, the U.S. Consumer Product Safety Commission (CPSC) released preliminary findings of the investigation it has been spearheading into drywall imported from China that is suspected of damaging homes and affecting homeowner health around the country. CPSC has been leading the coordinated federal effort since January 2009, tracking complaints from homeowners, conducting interviews and field measurements in homes, performing tests on samples taken from affected homes, and tracking the provenance of the defective drywall boards to locate their source. To date, 1,900 complaints of "rotten-egg" smells and corrosion of metal components and mechanical systems in homes, as well as asthma-like symptoms, headaches, and bloody noses, have been lodged with the CPSC from residents in 30 states. Most of the complaints have come from homeowners in Florida and Louisiana, likely due to the massive rebuilding of homes following hurricanes in 2004 and 2005.

According to the preliminary findings of CPSC's elemental and chemical testing, higher levels of two elements—sulfur and strontium—have been found in certain Chinese-made drywall products than in drywall manufactured elsewhere. More testing is being conducted to determine the relationship between the elevated levels of these elements and reported health symptoms or corrosion in homes. Chamber studies conducted by Lawrence Berkeley National Laboratory to detect chemicals emitted from drywall also determined that the Chinese-made drywall in question emits higher levels of volatile sulfur gases than drywall manufactured elsewhere. Further testing continues, including exposure and risk assessments.

CPSC also tested the indoor air of 10 homes in Florida and Louisiana to identify and measure contaminants present; this effort also will inform the development of a drywall home indoor air testing protocol. According to the CPSC, the study didn't detect or found very limited or occasional presence of the sulfur compounds hydrogen sulfide, carbon disulfide, and carbonyl sulfide. Acetaldehyde and formaldehyde—two known irritants and common components of adhesives and binders used in the manufacture of building materials and products—were found in homes with Chinese drywall in sufficient concentrations that could aggravate asthma and other conditions, but they were also found in homes without Chinese-made drywall.

CPSC reports that the high levels of formaldehyde detected were not unusual in newly constructed homes.

The researchers established that ventilation in homes plays an important role in managing indoor levels of formaldehyde. "What we found both in homes with Chinese drywall and without Chinese drywall is that when the air conditioner either wasn't working or was turned off, levels of formaldehyde were elevated," says Scott Wilson, CPSC director of public affairs. "But when the air conditioner was turned back on or a great deal of ventilation was provided in the house, those levels settled back down to levels that are expected in new homes."

However, it is too early to determine whether requirements for building envelope sealing or poor ventilation in homes are contributing factors to the corrosion damage and health issues reported in homes.

To date, the test results have not shown the connection between the elevated levels of sulfur compounds and gases, acetyldehyde, and formaldehyde in Chinese-made drywall and the reported health issues and corrosion, but Wilson says that CPSC believes that there is indeed a connection. The agency and its federal partners are continuing testing, and late in November will release the results of an indoor air study of 50 homes in Florida, Louisiana, Virginia, and Mississippi. This study will target lower concentration levels of the sulfur compounds in an effort to pinpoint the differences between Chinese-made drywall and U.S.-made drywall, the chemical interactions, and the impact to homes and human health at a more finely-tuned level, according to Wilson.

CPSC will conduct preliminary engineering analysis of electrical and fire safety issues associated with the reported corrosion, as well. The agency also is studying long-term corrosion issues, but this testing will not be completed until June 2010.

In a statement about the study findings, CPSC's chairman, Inez Tenenbaum said that during the recent Product Safety Summit in China, she called on Chinese drywall manufacturers to take responsibility and "do what is just and fair" if the U.S.'s federal investigation proves that drywall imported from China is defective.

Stephani L. Miller is Associate Editor of Custom Home.