Environmental Protection Agency Administrator Scott Pruitt issued a new directive on Tuesday banning scientists who receive agency grant money from serving on EPA advisory committees.

The unprecedented move to prevent scientists who receive federal funding from the EPA from advising the agency on the quality, relevance and use of science represents a sweeping shift in the way the EPA crafts environmental policy and regulation.

During a briefing with reporters, Pruitt argued that the decision ensures that the agency is "getting advice and counsel independent of the EPA."

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He estimated that members of three of the EPA's advisory committees – the Science Advisory Board, the Clean Air Scientific Advisory Committee and the Board of Scientific Counselors – had received over $77 million dollars in EPA grant funding while serving on committees that also oversee federal grant distribution. Pruitt added that scientists who currently receive grant money while serving on an advisory committee will have the option of choosing between the two.

"Whatever science we are involved in at the EPA should not be political science," Pruitt repeated throughout the briefing.

Pruitt also announced a push to diversify members of committees such as the Science Advisory Board, the Clean Air Scientific Advisory Committee and the Board of Scientific Counselors by increasing state, tribal and local participation and increasing geographic diversity of the membership.

Scientists and environmentalists were quick to blast Pruitt's new policy as one that prevents the most qualified scientists in the field from providing advice to the agency and as a way to stack the administrator's office with more industry-friendly voices.

"Let me get this: toss the independent scientists and appoint those beholden to special interests who have less knowledge about real risks," Terry Yosie, the director of the Science Advisory Board during the Reagan administration, tweeted in response to Pruitt's announcement.

When pressed on any examples Pruitt could provide to show that scientists who have received grant funding have provided conflicting advice, he told reporters that that it was in "poor form" to look back and give specific examples.

"I think what's better is just to look forward and make sure that these folks serve with independence is ensured and integrity is maintained in the process," Pruitt added.

Michael Halpern, deputy director of the Center for Science and Democracy at the Union of Concerned Scientists, called Pruitt's decision to frame federally funded scientists as having a conflict of interest "a ruse."

"It provides cover to remove good scientists and put people in place who are compromised," Halpern wrote in an email.

"There's no shortage of industry-friendly views in the administrator's office, including many of Pruitt's own staff who come from industry lobby groups. Science advisory committees are supposed to be there to help the agency and the public understand if the lobbyists and the insiders are telling it straight," he added.

The announcement coincided with Pruitt's appointment of three new leads to chair EPA advisory boards. During an event on Tuesday afternoon, Pruitt tapped Michael Honeycutt to lead the EPA's Science Advisory Board and Tony Cox to head up the Board of Scientific Counselors.

Honeycutt, a toxicologist for the Texas Commission on Environmental Quality and a doubter of Ozone depletion, told the Texas Observer that the EPA "ignores good science which demonstrates that a chemical is not as toxic as they think it is."