Under the proposed policy, the agency would no longer consider scientific research unless the underlying raw data can be made public for other scientists and industry groups to examine. As a result, regulators crafting future rules would quite likely find themselves restricted from using some of the most consequential environmental research of recent decades, such as studies linking air pollution to premature deaths or work that measures human exposure to pesticides and other chemicals.

The reason: These fields of research often require personal health information for thousands of individuals, who typically agree to participate only if the details of their lives are kept confidential.

The proposed new policy — the details of which are still being worked out — is championed by the E.P.A. administrator, Scott Pruitt, who has argued that releasing the raw data would let others test the scientific findings more thoroughly. “Mr. Pruitt believes that Americans deserve transparency,” said Liz Bowman, an E.P.A. spokeswoman.