More than 100 current and former employees of a federal agency charged with ensuring workplace safety warn that American workers face a greater risk of death and injury on the job as the Trump administration slashes the organization’s ranks.

In a letter to Congress, the National Institute for Occupational Safety and Health employees say that the agency’s mission is at risk due to the administration’s actions over the past several months.

“Without us, more workers will suffer preventable deaths, illnesses, and injuries,” the current and former NIOSH employees wrote in the letter, obtained exclusively by NBC News ahead of it being sent to members of Congress.

The letter is being sent to all of Congress but is directed at Sen. Bill Cassidy, R-La., chairman of the Senate Committee on Health, Education, Labor and Pensions, and its ranking member, Sen. Bernie Sanders, I-Vt., ahead of the committee’s scheduled meeting with Health and Human Services Secretary Robert F. Kennedy Jr. to discuss President Donald Trump’s proposed HHS budged for the 2026 fiscal year.

NIOSH is part of the Centers for Disease Control and Prevention, in the Department of Health and Human Services.

The cuts at the agency are part of Trump’s vow to shrink bureaucracy and curb its interference in private business.

The White House and the Department of Health and Human Services did not immediately respond to NBC News’ requests for comment.

The letter urges Congress to act to save the organization, especially at a time when the administration is calling for increased economic activity, including domestic manufacturing and mining.

It says over 90% of NIOSH employees have received “reduction-in-force” letters placing them on administrative leave pending more permanent layoffs.

Congress established NIOSH in 1970 as part of the Occupational Safety and Health Act “to assure as far as possible every working man and woman in the Nation safe and healthful working conditions and to preserve our human resources.”

While the U.S. Occupational Safety and Health Administration (OSHA) polices industries involved in worker injuries, NIOSH is tasked with establishing a vision for safer workplaces by conducting research, maintaining databases, certifying workplace equipment and collaborating with worksites on preventive training and other measures.

NIOSH oversees the health program for 9/11 responders and survivors, which could be all but abandoned if staff reductions are formalized, critics have said.

Michael O’Connell, who assisted with search-and-rescue operations as an early-career firefighter after 9/11, was diagnosed with a rare inflammatory disease called sarcoidosis that causes debilitating pain. He says he’s managed his symptoms with the help of NIOSH’s World Trade Center Health Program.

“It’s bureaucratic cruelty,” he said last month, addressing the cuts to the agency. “They’re trying to save money, which is fine, but don’t do it on the backs of the 9/11 community.”

If the reduction-in-force plans are carried out, the letter to Congress says, “nearly all of NIOSH’s functions will be ended permanently.”

The document was signed by accomplished scientists in the field of workplace safety, including Micah Niemeier-Walsh, a researcher on the effects of exposure to lithium-ion battery fires; Gary Roth, an expert in nanotechnology’s tiny scale and how it can bypass traditional human and workplace protections; and epidemiologist Scott Laney of the Coal Workers’ Health Surveillance Program, who has said the cuts have already resulted in coal miners’ X-rays for black lung going unexamined.

“NIOSH is at risk for imminent destruction,” the letter to Congress states. “The administration’s activities over the past several months have almost completely impeded NIOSH’s ability to carry out its mission.”

Some programs within NIOSH will move to a newly created agency known as the Administration for a Healthy America, NIOSH Director John Howard said in an agencywide email last month, but it’s unclear what will be left after the transition.

The signatories hold out hope for congressional action to save the agency.

“Please send a message to the Trump administration that today’s Congress still supports America’s workers by restoring and protecting NIOSH in its entirety and keeping it within CDC,” the letter states.