Test results released by the EPA indicate Chinese drywall has sulfur, strontium and other substances that are either nonexistent in American plasterboard or found in much lower levels, the Miami Herald reported Wednesday.
The EPA says the Chinese drywall also had organic material associated with acrylic paint not found in U.S.-made product.
Owners of newer homes in South Florida and other parts of the country have complained Chinese drywall makes their houses smell like rotten eggs and is causing wires and appliances to corrode and jewelry to blacken.
The EPA tests were conducted at the request of Democratic Sens. Bill Nelson of Florida and Mary Landrieu of Louisiana.
"We now know there are three things in there that aren't in other drywall samples," Nelson says.
He adds the next step is to find out how to fix the problem.