State and federal officials found traces of phosphogypsum in Chinese and domestic drywall samples they tested, but levels of the radioactive phosphate byproduct were so low that they don’t pose a hazard, according to a report released Friday. “Based on the analytical results from this limited sampling event, the technical team believes that neither the imported nor domestic drywall tested pose a radiological concern,” the report said. Those concerns were first raised by the Los Angeles Times, which reported in July that some Chinese manufacturers and trading firms exported drywall containing the radioactive material to the United States in 2006.
Phosphogypsum, or calcium sulfate, is produced when phosphate rock is processed into fertilizer. The U.S. Environmental Protection Agency said phosphogypsum contains high levels of uranium and radium-226, in some cases as much as 60 times more than the phosphate rock it came from. Because of that, the EPA has banned phosphogypsum’s use in construction since 1989.
But the Times said Chinese customs reports and interviews with Chinese executives indicated the byproduct was often added to drywall. That raised new fears among homeowners with Chinese drywall in their homes, which has been blamed for emitting putrid odors, corroding metal air-conditioning parts and possibly causing various health problems.
The news report prompted the U.S. Consumer Product Safety Commission, which is leading the federal investigation into imported drywall, to ask the EPA and the Florida Department of Health to test drywall samples.
Their findings: There’s some, but no more than what ordinarily would be found in the natural environment.
That should put the issue to rest, commission spokesman Scott Wolfson said.
“This was an issue that we responded to in mid-stream,” he said. “We all looked very closely at this issue and made a clear assessment based on the science.”
Wolfson said other aspects of the investigation are continuing, however.
The commission is conducting in-depth investigations into several dozen of the more than 1,100 drywall-related complaints it has received. The agency also is conducting air-sampling and testing in several homes in Florida, Louisiana and Virginia.
A California laboratory is examining the materials contained within Chinese drywall, and a Massachusetts lab has been hired to study the potential fire risk caused by the product. And a team of U.S. officials is expected to return today from a week-long trip to China that included visiting the source mines.