Preliminary findings from a federal investigation into potential health problems from drywall imported from China are inconclusive, the U.S. Consumer Product Safety Commission said on Oct. 29.

CPSC has received nearly 1,900 complaints from residents in 30 states about effects of Chinese-made wallboard. CPSC says preliminary tests found Chinese drywall has elemental sulfur and higher strontium concentrations than other types of drywall. But it says more studies are needed to show a link between the drywall and reported health problems.

In the meantime, the commission is working with the Dept. of Homeland Security to identify and stop imports of drywall from China, says CPSC Chairwoman Inez Tenenbaum. “We have identified hundreds of thousands of stockpiled boards, and we have sent notice to the warehouses where they are stored,” she said in an update to families who have contacted the CPSC about their concerns with drywall in their homes.

The latest findings came from three probes. The first study, a chemical analysis of drywall samples, found sulfur and strontium concentrations. Scientists found no radiation safety risk from the strontium, CPSC adds.

Preliminary findings from a second set of tests, conducted by Lawrence Berkeley National Laboratory, showed Chinese drywall emits volatile sulfur compounds at a higher rate than U.S.-made drywall. In addition, an analysis of indoor-air quality in 10 Florida and Louisiana homes, whose residents complained of “rotten- egg” smells and sulfur-like corrosion of copper and other metals, found sulfur gases either were not present or present only when outdoor levels of sulfur compounds were elevated.

Sen. Bill Nelson (D-Fla.) expressed frustration about the pace of the probe. “If you hear impatience in my voice, you are an accurate judge,” Nelson told officials with CPSC and other agencies on Oct. 29. “I simply don’t think [the investigation] is happening fast enough.” Officials say they hope to release conclusive results in late November.