The federal government said Monday that it has found a "strong association" between problematic imported Chinese drywall and corrosion of pipes and wires, a conclusion that supports complaints by thousands of homeowners over the last year.
In its second report on the potentially defective building materials, the U.S. Consumer Product Safety Commission said its investigation also has found a "possible" link between health problems reported by homeowners and higher-than-normal levels of hydrogen sulfide gas emitted from the wallboard coupled with formaldehyde, which is commonly found in new houses.
The commission, along with the Environmental Protection Agency and the Centers for Disease Control and Prevention, continues to study the potential health effects, and the long-term implications of the corrosion.
"We can say that we believe that there's a number of different chemicals that when brought together can be related to some of these irritant health effects that we've been getting reports of," said CPSC spokesman Scott Wolfson. "But we're still working toward that exact nexus."
The commission said it can now move forward with additional studies to identify effective remediation of the problem and potential assistance from the federal government. However, Warren Friedman of the U.S. Department of Housing and Urban Development said it's too soon to discuss specifics of any financial assistance homeowners could get.
The Formaldehyde Council, a trade group, said there is no scientific evidence to support the theory that the two chemicals can combine to sicken people.
Betsy Natz, the group's executive director, called it "irresponsible to speculate that formaldehyde and hydrogen sulfide can act in a synergistic ... manner to cause irritant effects in human beings at the low levels found in the CPSC study."
The CPSC has spent more than $3.5 million on the studies, and has received more than 2,000 homeowner complaints from 32 states, Washington, D.C., and Puerto Rico, in what is now the largest consumer product investigation in U.S. history. Most of the complaints have come from Florida, Louisiana, and Virginia. Wolfson said the CPSC has committed nearly 15 percent of its staff to the issue.
The results released Monday came, in part, from a 51-home indoor air quality study.
However, officials cautioned that not all Chinese drywall is necessarily problematic and that homes with American-made drywall also are being studied.
"Not all drywall is alike," said Jack McCarthy, president of Environmental Health & Engineering Inc., the firm hired by the government to perform the air quality tests. "It depends on what it's made of, not necessarily the country where it came from."
Added Wolfson: "We are not limited in the scope of our investigation to just Chinese drywall."
The commission released its first report on the drywall last month, noting further studies were needed before it could consider a recall, ban or other action.
Thousands of homeowners who bought new houses built with the imported Chinese building product are finding their lives in limbo as hundreds of 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. An Associated Press analysis of shipping records found that more than 500 million pounds of Chinese gypsum board was imported between 2004 and 2008 — enough to have built tens of thousands of homes.
They are heavily concentrated in the Southeast, especially Florida and areas of Louisiana and Mississippi hit hard by Hurricane Katrina.
The suspect building materials have previously been found by state and federal agencies to emit "volatile sulfur compounds" and produce a rotten-egg odor. Homeowners complain the fumes are corroding copper pipes, destroying TVs and air conditioners, blackening jewelry and silverware, and making them sick.
The federal government says China is assisting with the investigation.