The latest government study on Chinese drywall has revealed a “strong association” between the drywall and corrosion in homes that may physically irritate their inhabitants.

Government agencies, collectively called the “Interagency Drywall Task Force,” have been studying homes containing Chinese drywall because homeowners reported health problems and structural degradation after living in homes that used Chinese drywall from 2004-2007, when domestic drywall was in short supply.

Drywall building material–also called wallboard, gypsum board and plasterboard–is made of a flat sheet of gypsum covered on both sides with a thin layer of cardboard. It goes by such brand names as Sheetrock, Tablaroca, Gyprock and ToughRock.

A previous government study found no direct linkage between the drywall and the reported health problems and/or degradation. (See NU, Nov. 23, page 14.)

But the most recent report released last week–a 51-home study on behalf of the U.S. Consumer Product Safety Commission, and conducted by the Needham, Mass.-based Environmental Health & Engineering–found a linkage between the Chinese drywall, the level of hydrogen sulfide in homes with the drywall, and the corrosion of metal components in the homes.

“The two preliminary studies of corrosion of metal components, taken from homes containing the problem drywall, found copper sulfide in the initial samples tested, which supports the finding of an association between hydrogen sulfide and the corrosion,” according to the report.

CPSC noted that it has not yet been determined how the hydrogen sulfide gas is being created in homes built with Chinese drywall, but the hydrogen sulfide gas is the essential component that causes copper and silver sulfide corrosion found in the complaint homes.

Regarding health problems cited in the homes, the report stated: “While the study of 51 homes detected hydrogen sulfide and formaldehyde in homes containing the problem drywall at concentrations below irritant levels, it is possible that the additive or synergistic effects of these and other compounds in the subject homes could cause irritant effects.”

The report added that investigations are continuing.

CPSC said now that the corrosion association has been identified, the Interagency Drywall Task Force can “move forward to develop protocols that will identify homes with this corrosive environment and can determine the effectiveness of remediation methods.”

CPSC Chair Inez Tenenbaum said, “We now have the science that enables the task force to move ahead to the next phase–to develop both a screening process and effective remediation methods. Ongoing studies will examine health and safety effects, but we are now ready to get to work fixing this problem.”

However, the CPSC had to defend its study after a chemical trade group criticized one of its findings related to the presence of formaldehyde.

The Arlington, Va.-based Formaldehyde Council took exception to that finding and issued a statement.

The Formaldehyde Council, a group of chemical producers and manufacturing firms, lists its mission on its Web site as being “[t]o encourage accurate scientific evaluation of formaldehyde and formaldehyde-based materials and to communicate sound scientific information relating to the uses, benefits and sustainability of these products.”

Betsy Natz, executive director of the council, cited her group’s objections.

“Formaldehyde is not associated with corrosion and is not a component of dry wall. It is irresponsible to speculate that formaldehyde and hydrogen sulfide can act in a synergistic or additive manner to cause irritant effects in human beings at the low levels found in the CPSC study,” she said.

“This is particularly the case because the only statistically significant difference between the complaint and control homes examined in the study was the levels of hydrogen sulfide detected, while there was no difference between the levels of formaldehyde measured in each group,” she added.

Alex Filip, deputy director of public affairs for CPSC, responded that “our scientists said they believe there was an association between those two elements and other contaminants.”

He said the confusion may stem from the omission of “other contaminants” in some media reports. Some stories, he noted, only reported the hydrogen sulfide and formaldehyde combination.

“Our people believe it’s a synergistic effect of the two main things discovered [formaldehyde and hydrogen sulfide] and other contaminants,” he said.

In other drywall news, Louisiana Insurance Commissioner James Donelon held a press conference to announce that the state’s insurer of last resort–Citizens Property Insurance Corp.–will offer a policy to owners of property that has been vacated due to Chinese drywall problems. He said insurers have been non-renewing or cancelling the policies because the property is considered vacant.

Commissioner Donelon said these new policies may not have all the “whistles and bells” that standard homeowner policies might include, but they will offer protection at the same or cheaper rates, and satisfy the requirements of lenders to prevent foreclosures.

Commissioner Donelon also noted that, unique to the state of Louisiana, if a policyholder has been covered by a homeowners insurer for more than three years, the policy can’t be non-renewed or cancelled for reporting a problem such as Chinese drywall.