Last week the CDC reported a cluster of deaths.

Researchers at the Centers for Disease Control and Prevention (CDC) are trying to uncover why a cluster of dentists were diagnosed with a rare lung disease called idiopathic pulmonary fibrosis (IPF).

Acting on a tip from a dentist getting treatment for the lung disease at a Virginia clinic, the CDC found nine other dental professionals — eight dentists and one dental technician — had been treated for the same disease at the same clinic in the past decade.

That’s about 23 percent more than would be expected.

The news led the CDC to warn that those working in dental offices may have a higher rate of developing the disease than the general population.

Though no definitive cause was found, the risk appears to be tied to polishing dental tools and preparing the compounds used in fillings, particularly in closed spaces when respiratory masks aren’t used, the CDC said in its report on the disease “cluster,” released last week.

These activities can release certain dust particles known to cause respiratory problems.

In the case of IPF, inhaling those particles can sometimes, eventually, lead to a thickening of parts of the lungs. This makes it gradually harder to breath. People with IPF generally have just three to five years to live from the time of diagnosis, though some live as long as 10 years, according to Dr. Randall Nett, of the respiratory health division of the CDC’s National Institute for Occupational Safety and Health and lead author of the report on the Virginia cluster.

“In the literature, there’s been different lung diseases attributed to being around the dental practice,” Nett told Healthline. But as far as experts know, this is the first time the risk of dental professionals developing IPF has been noted, he explained.

Seven of the nine dental professionals with IPF at the Virginia clinic have already died.

Nett said those affected generally aren’t diagnosed until later in life, in their 50s, 60s, or 70s.

While the report is worrying, outside experts said the risk of developing lung disease is likely lower for those working in dental offices today.

“Today’s dentist does much less with materials that need to be polished and, in the process, generate dust and aerosol particles containing nonbiodegradable debris,” said Paul Casamassimo, a professor emeritus of pediatric dentistry at Ohio State University’s College of Dentistry and chief policy officer of the American Academy of Pediatric Dentistry’s Oral Health Research and Policy Center. “So, the exposure is not anything like it was a generation ago.”

He added that most dentists today rely on external laboratories with “rigorous industrial safety standards” for the riskier tasks once done by dentists. Dental offices also have to post warnings, and they can install devices to measure trace vapors that cause harm through long-term exposure.

“Today’s dental office is a much safer place in many ways,” Casamassimo told Healthline.

But he cautioned that risk still exists, and that today’s dentists need to use masks, glasses, and devices to vacuum up dust particles.

In a statement, the American Dental Association said it takes “very seriously the issue of occupational hazards. The ADA works in collaboration with OSHA [Occupational Safety and Health Administration] and the CDC to ensure the best possible guidance is available for dental professionals.”

Dangerous airborne particles are only one of the long-term risks dental professionals may face. Infectious agents, chemicals, and ionizing radiation are among the other hazards, the CDC report notes.

But the CDC note that, among respiratory diseases, the inhalation of silica or compounds used in dental implants can cause pneumoconiosis, when dust leads to inflammation and scarring in the lungs. Silicosis and asbestos-related lung disease have also been identified in dentists.

In a data set maintained by the CDC, the report authors found that those working in dental offices were about 1.5 times more likely to die from IPF or several related lung diseases than the general population.

But smoking and exposure to dust from rocks, metal, or wood can also lead to IPF. And dentists’ relatively higher income and education level would likely mean they’re more likely to seek treatment at clinics such as the one in Virginia. This potentially leads to an overrepresentation of dentists with IPF compared to the general population.

“So really we don’t know, so that’s why we need to do further studies,” said Nett. He said researchers will be meeting in the very near future to discuss next steps in the research.

Regardless of whether the overall incidence of IPF is as high as the Virginia clinic statistics would suggest, the report points to a broader problem with keeping dentists and doctors safe, Casamassimo said.

“Agencies like the FDA [U.S. Food and Drug Administration] do a good job minimizing untoward effects [of new drugs and therapies] on patients, but often do not address provider health. In truth, it may take years for some effects to show up, as in the case of the IPF deaths in the CDC report,” he said.

He also said dental education should do a lot more to advise dentists on how to not just keep their patients safe and healthy, but how to consider their own safety as well.