WASHINGTON — The Environmental Protection Agency announced a new regulation Tuesday that would restrict the kinds of scientific studies the agency can use when it develops policies, a move critics say will permanently weaken the agency’s ability to protect public health.
Under the measure, the E.P.A. will require that the underlying data for all scientific studies used by the agency to formulate air and water regulations be publicly available. That would sharply limit the number of studies available for consideration because much research relies on confidential health data from study subjects.
Scott Pruitt, the E.P.A. administrator, announced the proposed regulation this afternoon at agency headquarters, flanked by Republican lawmakers who sponsored legislation designed to achieve the same ends as the new regulation.
“The science that we use is going to be transparent, it’s going to be reproducible,” Mr. Pruitt said.
Supporters and critics alike say the policy will have far-reaching consequences that could limit the E.P.A.’s ability to regulate carbon emissions, air pollution and pesticides.
The new regulation means that some of the most important research of the past decades — for example, studies linking air pollution to premature deaths and measuring human exposure to pesticides — would not be available to policymakers if scientists were unwilling to break the confidentiality agreements they struck with study subjects in order to collect sensitive personal information.
Enacting the policy as a regulation, as the E.P.A. intends to do, will involve accepting comments from the public and going through a lengthy bureaucratic process. But, if finalized, the measure would be difficult for a future administration to unravel.
Public health and environmental groups have vowed to challenge the move in court.
Richard J. Lazarus, a professor of environmental law at Harvard, said Mr. Pruitt would be “walking into a judicial minefield” if he told the E.P.A. to no longer consider certain studies during agency rule-making.
That, Mr. Lazarus said, would be considered an arbitrary and capricious decision under the Administrative Procedure Act, which governs agency rule-making, and would “subject any agency regulation issued based on such a defective record to ready judicial invalidation.”
Supporters of the plan, which include the chemical and fossil-fuel industries and prominent climate change denialists, say the regulation will ensure that future E.P.A. policies are based on science that can be independently verified.
The proposed regulation was not available online in the Federal Register as Mr. Pruitt spoke, but an advance copy obtained by The New York Times stated that the measure was intended to “strengthen the transparency and validity of E.P.A. regulatory science” and emphasized the financial burdens created by federal regulations.
“When E.P.A. develops regulations, including regulations for which the public is likely to bear the cost to comply, using public resources, E.P.A. should require that the underlying scientific information is available to the public,” the summary of the regulation says.
The public will be given 30 days to offer comments on the proposal before a final rule is issued, according to the draft. The E.P.A. did not respond immediately to a request for comment.
The announcement comes as Mr. Pruitt prepares to face Congress on Thursday to discuss multiple questions about his frequent first-class travel, large security detail and other use of taxpayer dollars. His supporters said they are encouraged that the ethics cloud hanging over him has not stopped Mr. Pruitt from pursuing ambitious new policies.
“This is the most important thing he can do,” said Steven J. Milloy, a longtime champion of the measure who worked on President Trump’s E.P.A. transition team and who runs a website aimed at undermining the established science of human-caused climate change. “This will really open up E.P.A. science to public scrutiny.”
In an interview Sunday on WNYM-AM in New York, Mr. Pruitt said the measure would allow the public to test scientists’ findings for themselves.
“It gives people the opportunity in real time to peer review. It goes to the heart of what we should be about as an agency,” Mr. Pruitt said.
John Schwartz contributed reporting from New York.