U.S. Finds Strong Link Between Chinese Drywall and Corrosion

Federal safety officials say they have discovered a strong link between drywall made in China and the home corrosion reported by thousands of U.S. property owners whose homes used the drywall.

The results are from an indoor air study of 51 homes and come just weeks after the Consumer Product Safety Commission stopped short of linking the air quality and corrosion complaints with the Chinese-made building material and promised further study.

"We now can show a strong association between homes with the problem drywall and the levels of hydrogen sulfide in those homes and corrosion of metals in those homes," the CPSC said in its announcement of the air quality results.

The agency said it can now move forward working with Congress and the White House to develop effective remediation methods for homeowners and further investigate the health effects.

"Ongoing studies will examine health and safety effects, but we are now ready to get to work fixing this problem," said U.S. Consumer Product Safety Commission Chairman Inez Tenenbaum.

In addition to releasing the air quality findings, CPSC also unveiled additional preliminary research findings on corrosion safety issues.

One study compared 41 "complaint" homes in five states with 10 noncomplaint homes built around the same time in the same area as the complaint homes. The findings showed that hydrogen sulfide gas is the essential component that causes copper and silver sulfide corrosion found in the complaint homes. Other factors, including air exchange rates, formaldehyde and other air contaminants contribute to the reported problems.

In ways still to be determined, according to the researchers, hydrogen sulfide gas is being created in homes built with Chinese drywall. Earlier studies found large amounts of elemental sulfur in the Chinese drywall. CPSC is investigating drywall from other sources that may mimic the problems found with Chinese drywall. CPSC is meeting with drywall manufacturers and others who are studying this issue to take their findings into consideration.

The study also found elevated formaldehyde readings in both the control and complaint homes. This is typical for new, more air-tight homes due to items such as cabinets and carpets which emit formaldehyde. Both formaldehyde and hydrogen sulfide are known irritants at sufficiently high levels. The concentrations measured in this study were below those levels. Investigators believe that the additive or synergistic effects of these and other compounds in the subject homes could cause irritant effects evident in the homes.

While drywall-related corrosion is clearly evident, CPSC said long term safety effects are still under investigation.

To date, CPSC has received more than 2,000 reports from consumers and homeowners concerned about problem drywall in their homes.

The complaints have raised concerns for politicans, insurers and contractors.

CPSC said it continues to search for homes exhibiting the corrosion and health effects under study. In addition to a direct call to consumers, CPSC is contacting all states to ensure that all homes with these problems have been reported to CPSC.

Officials said they are also working with U.S. Customs and Border Protection to monitor imports of possible Chinese drywall but they believe that no new Chinese drywall has entered the U.S. in 2009.

CPSC said it has secured the cooperation of the Chinese government to help identify the sources and causes of this problem.

The technical research reports from CPSC are available online.