The Union of Concerned Scientists (UCS) said in a report on Thursday that the administration's policies could take years to undo and in the meantime the best and the brightest would be frightened away from jobs in the National Institutes of Health and other government institutions.
The union, chaired by Dr Kurt Gottfried, emeritus professor of physics at Cornell University, said more than 4000 scientists, including 48 Nobel laureates and members of both political parties, had joined the call for "restoration of scientific integrity in federal policymaking".
"I don't think one should simply assume that the problem ... will go away if there is a new administration in office," Gottfried told reporters in a telephone briefing.
"What is happening under this administration is a cultural change. We have to address this cultural change and fix it."
"Then the staffer
asked questions that really shocked me.
She wanted to know what I thought about President Bush: Did I like him, what did I think of the job he was doing?"
Dr Richard Myers,
Robert Paine, an ecologist at the University of Washington who chaired an advisory panel on endangered salmon and trout, said his team was warned by the government to remove facts that undermined policy.
"We were told to strip out specific scientific recommendations or see our report end up in a drawer," Paine said.
The report includes accusations of administration interference on strip mining, drug approvals and protection of endangered species.
Two recently appointed members to the National Advisory Council for Human Genome Research, Dr Richard Myers of Stanford University in California and Dr George Weinstock of Baylor College of Medicine in Texas, said they had been asked inappropriate questions when they were nominated.
Weinstock said a staffer at the Health and Human Services Department called to ask "leading political questions".
"There is no doubt in my mind that these questions represented a political litmus test," he said in a statement.
Scientists fear their research is
being judged by their politics
Myers said he received a similar call in which he was asked about his opinion of embryonic stem cell research, which the White House opposes.
"Then the staffer asked questions that really shocked me," Myers is quoted as saying in the report. "She wanted to know what I thought about President Bush: Did I like him, what did I think of the job he was doing?"
Dr Gerald Keusch, former Associate Director for International Research at NIH, said NIH staffers in Bethesda, Maryland, were being forced to put in travel requests to visit the offices of the Pan American Health Organisation "just a Metro trip away" in downtown Washington, DC.
"You are now required to submit a travel request six weeks ahead of time," said Keusch, who resigned last year.
"These are increasing bits of evidence of attempts at control over the way the business of science, the open communication between scientists, is being conducted."
The Union of Concerned Scientists previously levelled similar charges against the Bush administration in February. But White House science adviser John Marburger again rejected them.
"The material presented by the Union of Concerned Scientists resembles previous releases in making sweeping generalisations based on a patchwork of disjointed facts and accusations that reach conclusions that are wrong and misleading," Marburger said in a statement.
"As I have stated before, this administration values and supports science, both as a vital necessity for national security and economic strength and as an indispensable source of guidance for national policy."