A media statement released by Knauf on January 9, 2009 concludes
The company is conducting a thorough investigation and cooperating with builders that have contacted it. Studies and testing by nationally recognized experts are ongoing. The testing has confirmed that copper has blackened and may be caused by low levels of naturally occurring sulfur gases. The low levels of gases do not present a health risk to persons within the residences.
Knauf Tianjin is assessing remedial options to correct conditions that are identified with respect to its plasterboard, with the least intrusion for homeowners. The company remains committed to the health and safety of the ultimate consumers of its products in the construction industry.
From today’s (January 15, 2009) the News-Press, Fort Myers, FL, Cape Coral drywall comes up clean:
Knauf claims the Tianjin product is made from natural, not synthetic gypsum and the drywall that causes corrosion is unmarked and comes from another, unknown Chinese manufacturer.
The Tianjin drywall is safe, the company said.
However, health standards are only for eight hour-exposure in the workplace, not residential or chronic exposure, health officials say.
There seems to be some confusion here concerning health standards, and now there is an “unknown Chinese manufacturer” in the mix.
Regarding the concern over drywall in three schools and two public facilities in Cape Coral, here, all were checked for tainted Chinese drywall and were found to have used drywall from North America.