"I've never seen a situation where three Republicans and one Democrat come in and sound the alarm the way they have today," subcommittee Chairwoman Diana DeGette, a Colorado Democrat, said after the hearing.
Much of the criticisms from the former EPA heads focused on perceptions that the Trump administration was focusing on economic and financial interests, sidelining or rejecting science and minimizing environmental and health effects in moving to ease dozens of environmental regulations.
Asked for reaction, EPA spokesman Michael Abboud said current EPA administrator Andrew Wheeler was working to engage the agency's Science Advisory Board, or SAB.
"Administrator Wheeler will continue to work with the SAB and try to improve relations that the previous administration took for granted," Abboud said.
Abboud did not immediately comment on the broader criticisms. While his predecessors were testifying, however, Wheeler tweeted that the agency was balancing "our regulations to ensure a healthy and safe environment while also saving the taxpayer $3.6 billion. And we're just getting started."
With his comment, Wheeler tweeted a Washington Examiner article that quoted him as saying he had saved taxpayers that amount by rolling back 40 "major regulations, and plans to axe another 49."
Republicans on the subcommittee did not join the former EPA heads or Democratic lawmakers in expressing alarm at the rollbacks, most of which have targeted Obama-era measures on air, water, pesticides and other threats, and climate change.
Republicans instead said the EPA under past presidents had grown uncommunicative or adversarial with businesses and ordinary people. "Under your leadership, I think the EPA went rogue," Rep. David McKinley, a West Virginia Republican, told McCarthy.
During the regulation-cutting Reagan administration, Thomas told lawmakers, congressional oversight and unending press coverage of EPA changes would be enough to get the president himself to step in and make sure the agency was still following its mission of protecting public health and the environment.
There was sometimes the perception that when it came to the EPA, it was "jobs vs. the environment," Thomas said after the hearing. "There's been fifty years of history that says that's not the tradeoff."