Chinese Drywall Poses Potential Risks

Mary Ann Schultheis displays the black dust that is covering the copper tubes in the air conditioner of her Parkland, Fla. home.

The Chinese board was also cheaper. One homeowner told AP he saved $1,000 by building his house with it instead of a domestic product.

In 2006, enough wallboard was imported from China to build some 34,000 homes of roughly 2,000 square feet each, according to AP's analysis of the shipping records and estimates supplied by the nationwide drywall supplier United States Gypsum.

Experts and advocates say many homes may have been built with a mixture of Chinese and domestic drywall, potentially raising the number of affected homes much higher.

So far, the problem appears to be concentrated in the Southeast, which blossomed with new construction during the housing boom and where the damp climate appears to cause the gypsum in the building material to degrade more quickly. In Florida alone, more than 35,000 homes may contain the product, experts said.

In Louisiana, the state health department has received complaints from at least 350 people in just a few weeks. Many of the affected homeowners rebuilt after Hurricane Katrina only to face the prospect of tearing down their houses and rebuilding again.

In another cruel twist, some of the very communities that have been hit hardest by the collapse of the housing market and skyrocketing foreclosure rates are now at the epicenter of the drywall problem.

Foreman warns of a "sleeping beast" in the thousands of bank-owned condos and houses across the country, with no one in them to complain.

Outside the South, it's harder to pinpoint the number of affected homes. And in drier climates such as California and Nevada, it may be years before homeowners begin to see — and smell — what may be lurking inside their walls.

The drywall furor is the latest in a series of scares over potentially toxic imports from China. In 2007, Chinese authorities ratcheted up inspections and tightened restrictions on exports after manufacturers were found to have exported tainted cough syrup, toxic pet food and toys decorated with lead paint.

Scientists hope to understand the problem by studying the chemicals in the board. Drywall consists of wide, flat boards used to cover walls. It is often made from gypsum, a common mineral that can be mined or manufactured from the byproducts of coal-fired power plants.

Plaintiffs in the lawsuits, as well as U.S. wallboard manufacturers, say the tainted drywall was made with fly ash, a residue of coal combustion more commonly used in concrete mixtures.

Fly ash can be gathered before it ever reaches the smokestack, where technology is used to remove sulfur dioxide from the emissions. The process of "scrubbing" the smokestack emissions creates calcium sulfate, or gypsum, which can then used to make wallboard, experts say.

Haldin, the Knaupf Tianjin spokesman, says some domestic drywall is also made from the less-refined fly ash.

But Michael Gardner, executive director of the U.S. Gypsum Association, said American manufacturers gather the gypsum from the smokestacks after the scrubbing, which produces a cleaner product.

The Consumer Product Safety Commission has dispatched teams of toxicologists, electrical engineers and other experts to Florida to study the phenomenon. The commission is also working with the Environmental Protection Agency and the Centers for Disease Control and Prevention to determine whether there is a health hazard.

A Florida Department of Health analysis found the Chinese drywall emits "volatile sulfur compounds," and contains traces of strontium sulfide, which can produce the rotten-egg odor and reacts with air to corrode metals and wires.

But the agency says on its Web site that it "has not identified data suggesting an imminent or chronic health hazard at this time."

"We're continuing to test," said Susan Smith, a spokeswoman for the department, which has logged 230 complaints from homeowners.