Congress is investigating a Washington, D.C.-based firm which critics charge "manufactures uncertainty" on behalf of chemical companies to help keep their products free from government bans or other restrictions. "The tactics apparently employed by the Weinberg Group raise serious questions about whether science is for sale at these consulting groups," said Rep. John Dingell, D-Mich., chair of the Energy and Commerce Committee, in a statement Wednesday. His panel is heading up the probe.

Dingell's investigators have asked the Weinberg Group to produce records on work it has done involving a chemical known as Bisphenol A, used to make many plastic bottles including baby bottles and bottles under the Nalgene brand, and other chemicals. The Food and Drug Administration has long permitted its use, but in recent years concerns about the chemical have grown as studies have indicated low doses of the substance can disrupt hormone systems in laboratory animals and possibly increase the risk of cancer or other serious illness.

The American Chemistry Council has defended the chemical, saying scientists' concerns over Bisphenol A were "distinctly at odds" with findings from other studies by both government organizations and scientific bodies. "All of these evaluations support the conclusion that bisphenol-A is not a risk to human health at the extremely low levels to which consumers might be exposed," the group said. On its Web site, Nalgene's manufacturer, Nalge Nunc International, refers to research on Bisphenol A by the FDA, the Environmental Protection Agency, the American Plastics Council and "other reliable sources from around the world" to state "we firmly believe in the safety of our products."