Following the active hurricane seasons of 2004 and 2005, there was an upsurge in home construction. Demand for drywall exceeded the domestic supply, and a certain amount of drywall was imported from China. In June, 2008, the State of Florida’s Department of Health received its first call from a homeowner regarding sulfur odors related to drywall. By December, 2008, the federal Consumer Product Safety Commission (CPSC) received its first drywall-related complaints, and became the lead federal agency on this matter.
Some would later claim that tainted product was in Florida as early as 2001.
Most of what the CPSC was hearing involved obnoxious odors emanating from the drywall; corrosion of metal items inside the home—especially copper air conditioning coils; and short-term health effects usually related to the upper respiratory tract. By the end of September, 2009, the CPSC had received about 1,500 reports from residents in 27 states, the District of Columbia, and Puerto Rico, who believe their health symptoms or the corrosion of certain metal components in their homes are related to the presence of drywall produced in China. Florida and Louisiana have logged the majority of complaints, with 74% and 17% respectively.
A research paper entitled “Identification of Odor-Active Organic Sulfur Compounds in Gypsum Products” was published in the June, 2009 issue of Clean Soil Air Water. One of the findings was that suspect Chinese drywall, as well as the source gypsum ore, produced unpleasant sulfur-like odors, when compared to non-Chinese samples.
Further testing revealed the “sulfur-like odors” to be caused by hydrogen sulfide (H2S), carbonyl sulfide, and carbon disulfide. Many authorities believe that these sulfides are produced by sulfate-reducing bacteria living in the drywall, and blame poor manufacturing practices for this microbial contamination.
Sulfate-reducing bacteria slowly degrade tough-to-digest materials that are rich in cellulose in anaerobic environments. Rather than breathing oxygen, they “breathe” sulfate. Gypsum, the main constituent of drywall, is hydrated calcium sulfate. Drywall, of course, also contains plenty of cellulose, given its paper liner.
Interscan portable H2S analyzers are now being used to screen suspected residences for the presence of tainted Chinese drywall. While the instrument does not respond equally to all sulfide compounds, the one of predominant interest is hydrogen sulfide, so this can serve as an excellent marker for the presence of sulfides. A proper home inspection will also look for evidence of corrosive damage, and rule out the possibility that the sulfide is originating from some other source, such as sewer gas.
Once a home is confirmed to contain tainted Chinese drywall, a variety of remediation protocols can be employed. One promising technique is to fumigate the house with chlorine dioxide, a chemical that has been used successfully to eradicate Bacillus anthracis, the bacteria that causes anthrax, in numerous infected buildings. Chlorine dioxide has the double benefit of getting rid of the sulfides, as well as killing the suspect bacteria in the drywall.
Interscan portable chlorine dioxide analyzers are used to set the fumigant concentration, and to ensure that the gas has dispersed after treatment—before re-occupancy of the residence.
Once remediation procedures have been completed, an Interscan portable H2S is used to ensure that the sulfide concentration is below a prescribed level. We recommend the intermediate Minimal Risk Level of 20 parts-per-billion.
Estimates of affected homes range from 60,000 to more than 300,000, and some are terming this the worst environmental disaster in US history. We at Interscan are here to help.