Imported (Chinese) Gypsum Drywall
Forensic Analytical Consulting Services, May 21, 2009
Late in 2006, reports of “sulfur-like” odors associated with the use of gypsum drywall imported from China began to surface in the state of Florida. The use of imported drywall was likely due to a shortage of building materials during the housing boom that occurred from 2004 to early 2007, in addition to the heavy building and remodeling that followed hurricanes Katrina and Wilma. Complaints of odors have continued to mount in addition to observations of accelerated corrosion of exposed copper (e.g. pipes, wiring). As many as 40 other states may be affected as well, as the amount of drywall imported and used during the boom was substantial and far reaching.
Within the last few months, numerous news stories have been published regarding the issue and lawsuit filings have been increased at an exponential rate. Forensic Analytical has received numerous calls inquiring about environmental health issues regarding the drywall. As a service to our clients please find the summary below on the various issues.
The Symptoms
In general, buildings built prior to 2004 are not expected to have been substantially built with imported drywall (though it cannot be necessarily ruled out). Buildings built from 2004 to the present with the aforementioned problem drywall have been shown to potentially result in the following:
- The presence of sulfur-like or other unusual odors.
- Copper corrosion, indicated by black, sooty coating on un-insulated copper pipe or wiring. Common areas of copper corrosion include: pipe leading to the air handling units, air conditioner evaporator coils, and exposed copper wiring at light switches or other electrical outlets.
The Cause
Several laboratory tests have been conducted comparing the composition of imported drywall and drywall produced in the United States. As early as November of 2006, Knauf (Tianjin) Plasterboard Co. Ltd. (a producer of Chinese drywall), retained a company to perform tests on the suspect drywall. Analysis indicted the presence of iron disulfide mineral (a naturally occurring mineral also known as pyrite) in the imported drywall.
Testing conducted on behalf of the Florida Department of Health (FL - DOH) revealed the presence of strontium sulfide in addition to pyrite. Additionally, the imported drywall contained over 5% organic material (in contrast to only trace levels in US produced drywall). It is suspected that the presence of these sulfur containing minerals and/or the additional organic content is resulting in the observed odor; however, it is far from definitive at the current time. According to the analysis, heat and moisture may also potentially accelerate sulfur emissions, explaining why complaints initiated in the state of Florida.
More recently, the testing conducted on behalf of the US Environmental Protection Agency (EPA) showed that imported drywall had detectable levels of sulfur whereas US produced drywall did not. Strontium was detected in imported drywall at two to ten times the level in US drywall. Additionally, EPA’s analysis indicated the presence of two organic compounds (typically associated with acrylic paints) in imported drywall that were not found in US produced drywall.
In the presence of moisture, volatile sulfur compounds in the air then cause corrosion of copper metal surfaces resulting in black, sooty, copper oxide/copper sulfide corrosion product on the metal surface.
The Environmental Health Effects
In addition to the analysis of the composition of the drywall itself, studies have been conducted to attempt to quantify the airborne sources of odor, generally expected to be reduced sulfur containing compounds. Analysis conducted for Knauf Tianjin in 2006 indicated detectable levels of carbonyl sulfide and carbon disulfide. More recent testing conducted on behalf of Lennar homes (testing in 79 homes in Florida) indicated detectable levels of carbonyl sulfide and carbon disulfide in a portion of the sampled homes.
Concentrations of the reported sulfur compounds were relatively low and well below available risk evaluation values. Many reduced sulfur compounds have very low odor thresholds; however, odor itself is not a good indictor of hazard. Some dangerous chemicals have no odor or what some would consider a pleasant odor, while some safe substances may have a very offensive odor.
However, many questions remain regarding the ultimate evaluation of environmental health risk to emissions from imported drywall. The conditions experienced during the analysis noted above may not be indicative of typical, worst case, or all potential conditions that may be present during normal operation and occupancy of the subject buildings. Chemicals such as hydrogen sulfide are heavier than air and can build up in unventilated or confined spaces presenting a serious safety issue. Studies investigating the adverse health effects from chronic, low-level exposure to these volatile sulfur chemicals are limited. Studies in the affected buildings continue.
It is clear that corrosion of copper piping is occurring in the affected homes at unusually high rates. This corrosion could lead to failures of air conditioning systems and/or electrical systems that may result in comfort or safety issues. Additionally, corrosion could lead to premature pipe leaks resulting in water intrusion and microbial growth.
Forensic Analytical Services
Forensic Analytical has been asked by clients and concerned citizens to evaluate the environmental health impact of the installation of imported drywall in a number of ways, including:
- Conducting air sampling in potentially affected buildings for volatile sulfur compounds;
- collection of suspect drywall samples and submittal for chemical analysis of composition to look for sulfur compounds or to confirm the products production source (Imported vs. US);and consultation on resolving environmental health concerns, including general research, training and education.
An additional resource which may be useful:
FL DOH
We are standing by to provide our services as needed or to simply answer your questions. Please do not hesitate to contact us for assistance.
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