When organizations need to make an announcement they hope the public won’t pay much attention to, they often drop the news right before the weekend. On a Friday afternoon this past October, in the middle of a government shutdown, the National Institutes of Health director, Jay Bhattacharya, emailed his agency with unexpected news: Kyle Walsh, an epidemiologist, would become director of the National Institute of Environmental Health Sciences and the National Toxicology Program.

The appointment catapulted Walsh — a 41-year-old associate professor at Duke University — to the helm of a $914-million agency responsible for studying how agents in the environment, like toxic chemicals, affect human health. The role affords him tremendous power to shape the study of environmental health, but experts in the field were pretty much unanimous: Before rumors began spreading that Walsh was up for the job, few had even heard of him. “Kyle Walsh is completely unknown to virtually anyone in the field of environmental health sciences,” wrote David Eaton, a prominent environmental toxicologist, in an email to Undark. “His presence in the environmental health field is very limited,” said another scientist in the field.

Some researchers have praised Walsh’s research record, including his work that touches on environmental health and the brain. In comments given to The Cancer Letter, a trade publication, Mitchel Berger, a brain tumor researcher at the University of California, San Francisco, described Walsh as “a spectacular scientist” and “a thought leader in the field of environmental health as it relates to brain tumors and cancer in general.”

As news reports soon noted, Walsh has one other, more unusual, qualification: He is close with Vice President JD Vance. Walsh has publicly said that Vance officiated his wedding. In 2016, a Reddit account seemingly linked to Walsh described the future vice president as “my best friend.” A personal Facebook page that appears to belong to Walsh is topped by a large photo of Vance in front of a crowd of cheering supporters.

For people in the field, the appointment may leave open questions about Walsh’s vision for NIEHS, an agency that often works on politically sensitive topics, including issues like water fluoridation and pesticide safety that are central to the agenda of Health and Human Services Secretary Robert F. Kennedy, Jr. But some are optimistic about his tenure and say that recent changes at NIH suggest more support for the field.

Meanwhile, for some current and former NIH officials, the appointment has added to broader questions about how political considerations are shaping the appointment of senior officials at NIH under President Donald Trump — and what that would mean for the future of the world’s largest biomedical research organization.

An NIEHS spokesperson initially said Walsh would be available for a phone interview with Undark. Shortly afterward, however, the NIH reversed course, providing only written responses from Walsh. In them, Walsh reflected on his development as a scientist, from being a child in Ohio interested in genetics to a prospective college student curious about “why different groups of people experienced different rates of diseases, and what underlying causes might confer risk of those diseases.” He also discussed his goals for the agency, which he described as “a unique and exciting NIH institute with a lot of potential to grow.”

Shortly afterward, Undark sent brief follow-up questions, asking if Walsh wished to respond to concerns that his friendship with Vance had elevated him to the role, among other things. NIH initially declined to respond, but ultimately sent along a brief statement noting that “Dr. Walsh was selected because his scientific background and leadership experience directly align with the NIEHS mission.”

The NIH is a collection of 27 institutes and centers, each with a director wielding broad latitude to make funding decisions and, in the process, shape entire fields. Mark Histed, a scientist at NIH, drew a rough analogy to the National Football League: The NIH director is like the league’s commissioner, serving as the public face of the bigger organization. The institute directors are the NFL coaches and owners — the ones who actually lead the teams and make the day-to-day decisions that determine how each team will perform. These are “incredibly powerful, powerful positions that control the budget,” Histed said.

The president appoints the overall NIH director (who also must be confirmed by the Senate) and the head of the National Cancer Institute. The other 26 directors, historically, are selected by other scientists, without input from the White House. In the past, when the NIH needed to fill an open director position at any of the institutes, the NIH director convened a search committee, made up of senior agency scientists and outside academic researchers. Over the course of several months, the committee would headhunt for a new director, interview candidates, and finally recommend two or three finalists to the NIH director, who would make the final pick. (Technically, final decision-making power rests with the health secretary, but former longtime NIH officials said the secretary has historically deferred to the director.)

Once selected, institute and center directors may serve for decades, across multiple presidential administrations.

Soon after Trump’s inauguration, Lawrence Tabak, who had been second-in-command at NIH for much of the preceding 15 years, was abruptly pushed out. The changes soon extended to institute directors: By late spring, five institute directors had been ousted or placed on administrative leave; they were eventually all fired.

At the same time, rumors were circulating that Walsh would be taking a senior role at the agency — perhaps at NIEHS, which is located in Research Triangle Park, North Carolina, not far from his professor job at the Duke campus. But in June, Rick Woychik, the director of NIEHS since 2019, was appointed to another five-year term.

Then, in October, Woychik was moved to a role in the NIH director’s office helping to enact Kennedy’s Make America Healthy Again agenda, and Walsh took the helm of NIEHS.

In many ways, Walsh’s story parallels that of Vance: Like the vice president, he was raised in Ohio, attended Ohio State University, and received a graduate degree from Yale University.

Walsh went on to do a postdoc at UCSF. Much of his research there explored the link between genes and certain cancers, but, in an email to Undark, Walsh described growing more curious about the role of environmental factors, too. “My interest in environmental health was cemented as we began to see patients for whom genetics could not explain their brain tumor diagnosis, and population-based datasets where genetic contributions could not fully account for patterns of incidence that we observed,” Walsh wrote. In response, he continued, “I shifted my laboratory’s focus over the last decade to have greater emphasis on exogenous contributors — such as environmental exposures — to cancer and other diseases.”

In 2023, Walsh helped Vance and Sherrod Brown — at the time Ohio’s two U.S. senators —coordinate the response to a train derailment in East Palestine, Ohio, that exposed many people to toxic chemicals. “The goal was to ensure that ten years from now, residents would not find themselves experiencing a host of illnesses and asking questions with no answers,” Walsh told Undark.

According to a conflict-of-interest statement filed as part of a recent paper in the journal Cancer, Walsh has also done consulting work for BP America, a petroleum company. (Paul Takahashi, a spokesperson for BP America, declined to share details about the consulting relationship. In an email, the NIH did not provide details about the work, but told Undark it ended in 2023.)

Several former NIH officials said it was rare for a researcher with so little track record in a field to ascend to lead an NIH institute. “It’s exceptionally unusual that someone would be appointed to head an institute that they had not ever received a grant from,” said Joshua Gordon, who led the National Institute of Mental Health from 2016 to 2024, and who said he had served on several search committees for other institute directors.

The seeming lack of a rigorous vetting process, too, raised questions. “I cannot remember any case of an IC director being selected in that particular way,” said Mike Lauer, who oversaw the NIH’s extramural grant program until early 2025, using an acronym that refers to institute and center directorships. “The cronyism is just so blatant,” said another former senior official, who spoke on condition of anonymity.

The appointment has generated speculation about how NIH leadership would fill the 15 institute and center director positions that are currently open. When the NIH listed many of those positions in early November, the application window was only for two weeks, according to reporting in Science. That was much shorter than the typical search window, said several formal officials. (It was ultimately extended to around five weeks, still considerably shorter than the typical period.) Multiple people close to NIH told Undark they were not aware of the agency using full search committees, with external members, to fill most of those roles. In comments sent from an HHS press email account to Undark in early January, the agency seemed to confirm this, writing only that “an NIH leadership team with experience in scientific agency management” was conducting the searches.

For researchers in the world of environmental health, it’s unclear what role Walsh will play at NIEHS. It’s also unclear whether the Trump administration has a particular interest in the institute — and, if so, which way that interest may go. NIEHS has sometimes been under fire from industry groups, who argue that it has been too quick to ascribe health hazards to chemicals that are of economic value. At the same time, NIEHS studies areas of special interest to Kennedy and the Make America Healthy Again movement.

“NIEHS is well aligned with Secretary Kennedy’s goals because the reality is that our environment can influence health not only acutely but in a chronic, long-term way, and our research has shown this,” Walsh wrote to Undark. His institute is “benefiting from the Secretary’s ability to amplify this message,” Walsh added.

In the email, Walsh laid out a range of priorities for NIEHS, including programs to offer more support for scientific trainees, and a greater focus on the emerging field of exposomics, which seeks to study many chemical and other environmental exposures at once, over time. “There are many contaminants that people may be concerned about, but from a research perspective, approaching each exposure one at a time is slow and arduous, and not always effective,” Walsh wrote.

He also singled out the agency’s role in disaster response.

Gary Miller, an environmental health science researcher at Columbia University and expert in exposomics, spent time in January attending a scientific meeting at NIH with Walsh and other researchers. Some of his colleagues, he acknowledged, feared the appointment would be “the end of the world for environmental health sciences.” Miller described himself as impressed after spending time with Walsh: “Either he’s been thinking about the environment for a long time, or is an extremely quick study.”

“I think we have a rare opportunity here, in that you have a director of this institute who is very close to the White House,” Miller said.

Miller and some others in the field have argued that NIH, in a push to focus on genetics, has sometimes overlooked research on the link between environmental exposures and health. The Walsh appointment, he argued, is part of a larger pattern that should be encouraging for the field, including the elevation of Woychik and another former NIEHS official, Nicole Kleinstreuer, to senior positions in the office of the NIH director. “We finally got our environmental people in the director’s office,” Miller said.

Darryl Hood, who sits on the National Advisory Environmental Health Sciences Council, is a professor at Ohio State University and an expert on how the environment impacts health. Hood has been involved in the East Palestine response, and he said he has known of Walsh’s work for years. The elevation of Woychik and Walsh, he told Undark, offers a chance to bring research on toxic chemical exposures and chronic disease more squarely into the work of NIH. “This is an opportunity to advance science,” Hood said. “To advance the study of chemicals in the environment and the negative impacts that they have on communities.”

NIEHS director Kyle Walsh helps cut the ribbon for the grand opening of the NIH’s East Palestine Train Derailment Health Research Program Office in Ohio on Feb. 3.
Visual: Undark

Walsh speaks before the ribbon cutting in East Palestine. “This is an incredibly important opportunity,” he told Undark separately, “for us to show that we can be responsive, as responsive as possible.”
Visual: Undark

In early February, Walsh was in East Palestine for the third anniversary of the derailment, and the opening of an NIEHS-funded research program office dedicated to studying the long-term health effects of disaster.

The office is at The Way Station, a Christian nonprofit around a mile from the spot where 38 Norfolk Southern train cars derailed, with many spewing hazardous chemicals into the air and water. Walsh, wearing a charcoal suit and standing by a chalkboard in the building chapel, offered some remarks before the ribbon-cutting ceremony. “This is really very meaningful to me, both personally and in my role as the director of the National Institute of Environmental Health Sciences,” Walsh said, noting that he had grown up in nearby Chardon, Ohio.

The day before, he and other researchers had met with community members. “These were sessions where, you know, investigators, the NIEHS director, we sat and listened,” he said. “We were not here to tell people what to worry about and what not to worry about. We wanted to hear about their concerns, their worries, what their hopes are for the future, and learn what we can do to support that.”

Afterward, Walsh responded briefly to a question about why the derailment matters to NIH. Once again, he made the case that researchers should be listening to people’s needs: “This is an incredibly important opportunity,” he said, “for us to show that we can be responsive, as responsive as possible.”