An Ocean Engineer and a Nuclear Physicist Walk Into Congress …

The report became a liability for the incumbent Republican, Peter Roskam, who had received campaign contributions from the American Chemistry Council. The council and Sterigenics had been lobbying the E.P.A. for several years not to classify ethylene oxide as a known human carcinogen, and Mr. Roskam — whose spokeswoman declined to make him available for an interview — had supported legislation to put industry representatives on the E.P.A. boards that make such decisions.

Now that they are in Washington, the Democratic scientists-turned-representatives face a new challenge. Many of them said that, beyond addressing climate change and other science-related issues, they wanted to bring a more scientific mind-set to Congress.

For the last six years, the House Committee on Science, Space and Technology was led by Lamar Smith, a Texas Republican with no scientific background. Under him, the committee investigated the debunked idea that global warming had “paused,” subpoenaed organizations whose research affirmed the reality of climate change, and promoted rules that reduced the number of scientists and increased the number of industry representatives on E.P.A. advisory panels. At times, committee members showed a basic lack of scientific knowledge: During a hearing in 2014, Steve Stockman, another Texas Republican, said it was nonsensical to think melting glaciers and ice sheets would increase sea levels because glasses don’t overflow when the ice cubes in them melt.

Mr. Smith has now retired, and four other Republicans on the committee were not re-elected. The new chairwoman, Eddie Bernice Johnson, a Texas Democrat and former psychiatric nurse, is the first person with a scientific background to hold that position since the 1990s. Ms. Johnson said in an interview that she had invited the new scientists to join, though committee assignments may not be finalized for several weeks.

But the old dynamics are not going to disappear.

There will continue to be tension even with some of the scientists on the other side of the aisle: Mr. Hern, the aerospace engineer elected in Oklahoma, has questioned whether human activity is the primary cause of climate change, and Mr. Green, the doctor from Tennessee, repeated the debunked claim that vaccines can cause autism. (He later backtracked, telling HuffPost that children should be vaccinated.) They, too, feel their experience gives them a more authoritative voice and, in Mr. Hern’s words, “an understanding of many of the issues that others might not have.”