The Consumer Product Safety Commission, which is leading the multi-agency investigation, said it needs to further study the matter before it can consider a recall, ban or other solutions to help affected homeowners. Additional results from ongoing studies were due to be released next month.
"The expansive investigation and scientific work that has been done and continues to be carried out is all aimed at providing answers and solutions," Lori Saltzman, a director in the CPSC's Office of Hazard Identification and Reduction, said Thursday. "No connections have been made yet."
Saltzman said the agency, which has so far spent $3.5 million on the studies, has received nearly 1,900 homeowner complaints during one of its largest consumer product investigations in U.S. history.
"We understand this problem has literally driven people from their homes," she said.
Homeowners, however, were frustrated by a lack of answers.
"So many of us have been really waiting on these results released today to offer us encouragement, but in fact, we're quite disappointed," said Holly Krulik, of Parkland, Fla., about 45 miles north of Miami.
Krulik and her husband, Doug, along with their two young children, moved in with her parents about six months ago because she says the Chinese wallboard in their home was making them sick and ruining the house.
"We're hanging on by a thread here. When is help going to arrive?" said Krulik, who will soon join hundreds of others who have filed lawsuits.
Thousands of homeowners like the Kruliks who bought new houses built with the potentially defective materials are finding their lives in limbo as the lawsuits against builders, contractors, suppliers and manufacturers wind through the courts.
During the height of the U.S. housing boom, with building materials in short supply, American construction companies imported millions of pounds of Chinese-made drywall because it was abundant and cheap.
A document obtained by CBS News shows that by 2006, 228 million kilograms - about 500 million pounds - was imported into the U.S. from 20 companies in China.
CBS News Investigates: Homeowners' Nightmare
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See images of defective drywall and learn more from the Florida Department of Health
They are heavily concentrated in the Southeast, especially Florida and areas of Louisiana and Mississippi hit hard by Hurricane Katrina.
The defective materials have since been found by state and federal agencies to emit "volatile sulfur compounds." Officials have also found traces of strontium sulfide, which can produce a rotten-egg odor, along with organic compounds not found in American-made drywall. Homeowners complain the fumes are corroding copper pipes, destroying TVs and air conditioners, blackening jewelry and silverware, and making them sick.
And some homeowners are reporting that their insurance companies are dropping or refusing to renew their policies based on the presence of the wallboard in their houses, putting them at risk of foreclosure.
The federal test results released Thursday largely confirmed what prior testing had found. The multiple agencies investigating, including the CPSC, the Environmental Protection Agency and the Centers for Disease Control and Prevention, acknowledged the reported health symptoms are consistent with some sort of contamination. But the culprit is unclear.
The Chinese government is assisting with the investigation.
"We're prepared to work with our partners across government on remediation and rehousing families impacted by this problem and to help families whose homes have lost value," said Dr. Warren Friedman of the U.S. Department of Housing and Urban Development.
In the meantime, he suggested affected homeowners contact their lenders for assistance or seek help through local grant programs, but he could not yet say what sort of federal help might be offered.