The U.S. Environmental Protection Agency has issued a proposed rule for strengthening transparency in regulatory science (April 30, 2018, 83 Federal Register 18768), which stipulates that EPA will ensure that the data and models underlying the pivotal science that informs significant regulatory actions are made publicly available, in a format that allows for outside analysis and validation. In a July 16 letter to EPA's acting administrator, the presidents of the National Academy of Sciences, National Academy of Engineering, and National Academy of Medicine said that while EPA's proposed provision is generally consistent with advice from the National Academies, overly stringent requirements for transparency may cause valid evidence to be discarded and thereby pose a threat to the credibility of regulatory science. In the letter, the presidents pointed to several National Academies reports to help inform EPA decisions about the proposed rule, and cautioned that the rule's "scope, complexities, and potential serious implications for regulatory science and action clearly warrant additional thorough, independent, objective, and context-specific evaluation and analysis."