The Centers for Disease Control and Prevention has begun a process that could lead to the firing of an Atlanta scientist who tried to make public environmental dangers in the Great Lakes region and in trailers housing Hurricane Katrina's victims, congressional investigators said.

In a letter dated Thursday, lawmakers warned CDC Director Julie Gerberding to immediately stop all personnel actions against toxicologist Christopher De Rosa — and any other staff involved in a report about environmental health issues in Great Lakes states.

"Courageous individuals who are willing to go public with evidence of wrongdoing are critical to ferreting out waste, fraud and abuse in government agencies," U.S. Rep. John Dingell, chairman of the House Committee on Energy and Commerce, said in a statement.

"The committee will fully investigate how CDC has treated Dr. De Rosa to determine whether it has violated federal whistle-blower laws and whether their behavior has been otherwise proper," said Dingell (D-Mich.).

CDC spokesman Tom Skinner, reached late Thursday, said the agency has been cooperating with the committee's investigators and will respond to the letter. Skinner said it's against CDC policy to comment on a specific personnel action.

De Rosa could not be reached for comment. Last fall, De Rosa was removed as director of the division of toxicology and environmental medicine in the CDC's Agency for Toxic Substances and Disease Registry, a position he'd held since 1992. Since that time, he's been given a title of "special assistant," but lacks any responsibilities, congressional investigators have said.

In an interview with the Journal-Constitution last month, De Rosa said he was demoted for insisting the CDC thoroughly investigate the long-term health risks of formaldehyde in trailers the federal government purchased to house victims of Hurricane Katrina. The CDC and the Federal Emergency Management Agency announced in February that thousands of Katrina victims need to be moved out of trailers because of dangerous levels of formaldehyde, a colorless gas used in the production of plywood.

Also playing a role in his demotion, De Rosa said, was his effort to have the CDC release the Great Lakes draft report, which identified abnormally high rates of health problems in areas near toxic waste sites around Detroit, Chicago, Cleveland and other cities and called for further study.

Another congressional committee — the House Committee on Science and Technology — is investigating whether the CDC until last year intentionally avoided examining the cancer threat posed by formaldehyde fumes inside the trailers. It has scheduled a hearing Tuesday titled, "Have the Centers for Disease Control failed to protect public health?" That committee warned Gerberding in a Feb. 6 letter not to retaliate further against De Rosa.

On Feb. 21, the CDC put De Rosa on a 90-day Personal Improvement Plan, "which is a formal step toward termination," Dingell said in his letter to Gerberding. CDC officials have denied any retaliation or suppression of science. They said the release of the Great Lakes report was delayed because of flawed science.

To reach staff writer Alison Young, call 404-526-7372.