WASHINGTON — Members of Vice President Dick Cheney's staff censored congressional testimony by a top federal official on the health threats posed by global warming, a former Environmental Protection Agency official said Tuesday.

In a letter to Sen. Barbara Boxer, D-Calif., former EPA deputy associate administrator Jason Burnett said an official from Cheney's office ordered that six pages be edited out of the testimony of Julie Gerberding, director of the Centers for Disease Control and Prevention, last October.

Several media outlets, including The Washington Post, reported at the time that Gerberding had planned to say that "CDC considers climate change a serious public health concern," among other passages. White House officials said then that they questioned the scientific basis of aspects of Gerberding's draft testimony.

Boxer, who chairs the Senate Environment and Public Works Committee, said the administration feared Gerberding's testimony would force it to regulate greenhouse gas emissions from burning fossil fuels.

"The Council on Environmental Quality and the Office of the Vice President were seeking deletions to the CDC testimony," Burnett, a 31-year old Stanford-trained economist and a Democrat, wrote in response to an inquiry from Boxer's committee. "CEQ requested that I work with CDC to remove from the testimony any discussion of the human health consequences of climate change."

Burnett — a grandson of high-tech entrepreneur David Packard and a member of the Packard Foundation's board of trustees — did not identify who in the vice president's office called him.

"I'm not interested in pointing fingers at any individual," he said at a news conference with Boxer, adding that he was focused on how the federal government will address climate change in response to a Supreme Court decision last year requiring the EPA to deal with the issue of rising carbon dioxide emissions.

Boxer demanded that, in light of Burnett's allegations, EPA administrator Stephen Johnson turn over "every document related to the agency's finding that global warming poses a danger to the public" — a determination the EPA reached late last year in a document that has never been made public. On that basis, the senator said, the EPA must issue regulations to limit the emissions. The White House refused to open the EPA e-mail containing that finding, which Burnett sent over Dec. 5, leaving the recommendation in limbo.

"I'm calling on Mr. Johnson to act now, and if he doesn't have the courage or the strength or determination to act, he should resign," Boxer said.

EPA spokesman Jonathan Shradar said Johnson would not provide the documents, but added that Boxer and others would be able to read about the agency's findings in detail when it releases its proposed regulation on greenhouse gases, expected within days.

Cheney spokeswoman Lea Anne McBride declined to comment on Burnett's allegations. White House spokesman Tony Fratto noted White House officials in past administrations have vetted congressional testimony from agency officials.

"There's absolutely nothing unusual here in terms of the inter-agency review process, whether it's testimony, rules or anything else," Fratto said in an interview.

Frank O'Donnell, who heads the advocacy group Clean Air Watch, said the revelations confirmed the vice president has been steering environmental policy during Bush's tenure.

"For years we've suspected that Cheney was the puppeteer for administration policy on global warming," O'Donnell said. "This kiss-and-tell account appears to confirm the worst."

Boxer was particularly harsh in assessing the earlier comments of White House spokeswoman Dana Perino, who in October said some of Gerberding's original draft "did not comport with" the 2007 report of the United Nations' Intergovernmental Panel on Climate Change.

"This was a lie," Boxer said, reading Perino's quote. "She said it was in contradiction with the IPCC report. It wasn't."