MANATEE — It’s been blamed for corroding air-conditioning units, emitting noxious fumes, short-circuiting microwaves and causing a multitude of health ailments.
Now, “radioactive” has been added to the list of Chinese drywall’s potential ills.
The Los Angeles Times, citing Chinese customs reports and interviews with Chinese executives, reported Saturday that some Chinese manufacturers and trading firms exported drywall containing radioactive phosphorus waste to the United States in 2006.
The waste, called 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 quoted several Chinese sources as saying that Chinese drywall manufacturers have been using the substance for at least a decade because it is cheap, widely available and not subject to government restrictions. An Internet search by the Bradenton Herald on Monday also found companies in Thailand and South Africa offering drywall made with phosphogypsum.
The Times’ Chinese sources speculated the phosphogypsum was causing the foul odors, corroded air-conditioning coils and health problems reported by hundreds of homeowners in Florida and elsewhere. Most involve houses built during the 2004-06 housing boom, when Chinese drywall imports surged as domestic supplies dwindled.
But state health officials and independent experts are discounting the report, saying tests have found no evidence of phosphogypsum in Chinese drywall samples taken from Florida homes.
“There’s no evidence to support that claim, and all the evidence points in the other direction,” said Gary Rosen, a Davie environmental/construction consultant who is investigating the drywall issue.
The Florida Department of Health said testing done earlier this year found low radiation levels in four Chinese drywall samples taken from troubled homes.
“Testing of the drywall for radiation demonstrated very low levels of the kind of radiation you would expect from materials derived from rocks,” the agency said on its Chinese drywall Web site. “This radiation is part of the natural background level in our environment.”
An agency spokeswoman confirmed Monday that those results have not changed. Instead, investigators are focusing on high levels of sulfur, strontium and organic materials in Chinese drywall as more likely culprits.
Duane Marsteller, transportation/growth and development reporter, can be reached at 745-7080, ext. 2630.