Researchers do not know for certain what causes the chemical reactions, but an MIT scientist said the mixture of gypsum and cellulose in Brincku's wallboard, combined with the humid atmosphere in Florida, was releasing sulfurous gases, causing corrosion of copper, brass and silver.

"The only solution is removal of the drywall," Thomas Eagar, an MIT professor of materials engineering, wrote in his report. He did not return a call from the Associated Press.

Most of the drywall in Brincku's home was made by Charlotte-based National Gypsum, which said its own testing found the material from the house contained just 4% cellulose.

"We absolutely don't know how you could make wallboard with 50% cellulose. It just simply would not hold together," spokeswoman Nancy Spurlock said. "We have been producing wallboard for 85 years in the United States, and we have never had a problem" similar to the Chinese drywall complaints.

Although Brincku has not sued, several other lawsuits have now been filed against American drywall manufacturers, including National Gypsum and Atlanta-based Georgia-Pacific.

Georgia-Pacific declined to comment on the litigation, but spokesman James Malone said the company had heard no such complaints until now.

Attorney Brian Warwick, who is suing Georgia-Pacific in federal court on behalf of two Florida homeowners, said his clients also heard the reports about Chinese drywall and assumed their homes were built with the imported materials.

He believes reports of tainted U.S. building materials will increase as homeowners realize the problem is not just with some Chinese wallboard.

"All the media keeps focusing on is China, China, China," he said. "So how many people are just dismissing their claims because they see they don't have Chinese drywall, and think they don't have tainted drywall?"