They saw “significant weaknesses in the scientific analysis of the proposed rule” to roll back vehicle emission standards, a centerpiece of the Obama administration’s effort to combat climate change.
As for the proposal to limit scientific data in health regulations, the scientists wrote that “key considerations that should inform the proposed rule have been omitted from the proposal or presented without analysis.”
The letters come as the Trump administration contends with mounting criticism that its policies have ignored, distorted or marginalized scientific data at the expense of the environment, public health and legal obligations.
Legal experts said the advisory body’s opinion could undermine the Trump administration’s rollbacks in the courts. “The courts basically say if you’re going to ignore the advice of your own experts you have to have really good reasons for that,” said Patrick Parenteau, a professor of law with the Vermont Law School. “And not just policy reasons but reasons that go to the merits of what the critiques are saying.”
Many scientists on the advisory board were selected by Trump administration officials early in the administration, as President Trump sought to move forward with an aggressive agenda of weakening environmental regulations. During the first year of the Trump administration, more than a quarter of the academic scientists on the panel departed or were dismissed, and many were replaced by scientists with industry ties who were perceived as likely to be more friendly to the industries that the E.P.A. regulates.
“We are trying to give the E.P.A. the best science it can in order to make decisions,” said Dr. Michael Honeycutt, the new head of the E.P.A.’s scientific advisory board, who had a reputation at the Texas Council on Environmental Quality for supporting policies that were more lax than those pushed by the federal government.
“We’re all scientists,” he said in an interview Tuesday. “I’ve never worked with a group of people more dedicated to trying to get the science right. We take this very seriously.”
Corry Schiermeyer, a spokeswoman for the E.P.A., said on Tuesday that the agency “always appreciates and respects the work and advice” of the scientific advisory board, while noting that Tuesday’s letters are drafts and could still be revised.
Some early critics of the Trump administration’s purge of the advisory-panel members said on Tuesday that their judgments may have been misplaced. Chris Zarba, who previously served as director of the E.P.A. science panel, credited the group for insisting on doing a comprehensive review of E.P.A. rules and said the work the group did points to the importance of the board remaining independent.
“It certainly looks like they were raising some very serious issues. I give them credit so far for stepping up and putting science first,” Mr. Zarba said.
Peter Wilcoxen, professor of public administration at Syracuse University, said he took the criticism as a hopeful sign. “The people on the board, regardless of what their affiliation was when they were appointed to it, took their role of trying to have the agency do the best science possible seriously. They weren’t on there just to try to politically steer the board one way or another,” he said.
Mr. Wilcoxen chaired the working group that reviewed the E.P.A.’s rollback of automobile tailpipe emission standards and said the agency’s analysis had several well-known “core flaws.”
One of the primary problems, he said, is that the E.P.A., in an unusual move, used a flawed economic model that had not been reviewed either internally by federal agencies or in the academic literature. That model found what Mr. Wilcoxen described as the “really improbable” results that relaxing Obama-era gas mileage standards would lead to a significantly smaller fleet of vehicles despite the model’s prediction that the vehicles would be cheaper.
That assumption helped drive the Trump administration’s argument that its rule would lead to fewer cars on the road and therefore fewer planet-warming emissions.
“They ended up with this result that basically violated introductory economics,” Mr. Wilcoxen said.
Ms. Schiermeyer, the E.P.A. spokeswoman, said the new auto pollution rule “will benefit all Americans by improving the U.S. fleet’s fuel economy, reducing air pollution, and making new vehicles more affordable for all Americans.”
Dr. John Guckenheimer, a mathematician at Cornell, was appointed in 2019 to the E.P.A. panel and worked on the analysis of the Trump administration’s plan to replace the Obama-era water protection rule, known as Waters of the United States. That rule defined bodies of water subject to federal protection from pollution under the Clean Water Act as major lakes and rivers.
But in a move that enraged farmers and lawmakers who represent rural areas, it also applied regulatory standards to the smaller streams and wetlands that drain into them, including seasonally intermittent streams and underground water passages.
The Trump administration’s proposed replacement would strip away protections from many wetlands, seasonal streams, and bodies of water linked only by underground connections. Dr. Guckenheimer said that proposal ignored the established science showing that even those wetlands and underground streams have a significant impact on the health of larger bodies.
The new proposal is “based upon speculation about what the courts will decide, rather than really having much scientific substance,” he said.
Environmentalists welcomed the draft reports.
“They are saying that the Trump proposal is entirely untethered from the scientific evidence, and that the scientific record for the rule that the administration is trying to replace remains unrefuted and very solid,” said Jon Devine, an expert in water policy with the Natural Resources Defense Council, an advocacy group. “And any self-respecting scientist is going to say that.”
Ms. Schiermeyer, the E.P.A. spokeswoman, wrote that despite the scientific board’s findings on the impact of the water rule, the administration was bound by the letter of the law, rather than science. “The definition of ‘waters of the United States’ may be informed by science, but science cannot dictate where to draw the line between federal and state or tribal waters, as those are legal distinctions established within the overall framework and construct of the Clean Water Act,” she wrote.
In its review of a proposed effort to limit the science used to write public health rules, the Science Advisory Board criticized the agency, saying the E.P.A. “has not fully identified the problem to be addressed” by the new rule.
Under the new effort, the E.P.A. plans to require that scientists disclose all of their raw data, including confidential medical records, before the agency could consider an academic study’s conclusions. E.P.A. officials called the plan a step toward transparency and said the disclosure of raw data would allow conclusions to be verified independently.
But, the advisory board warned, some requirements of the proposal “may not add transparency, and even may make some kinds of research more difficult.”
Critics including scientific and medical groups have said the rule would make it more difficult to enact new clean air and water rules because many studies detailing the links between pollution and disease rely on personal health information gathered under confidentiality agreements.