A report published by the Centers for Disease Control and Prevention (CDC) found that nine dentists in Virginia were found to have idiopathic pulmonary fibrosis (IPF) between the years 2000 and 2015.

Overall, the researchers found 894 patients diagnosed with IPF at a medical center in Virginia. Dentists made up just 1 percent of IPF patients documented in the study. However, researchers note that number is striking when considering the number of dentists in the United States.

Of the nine dentists in the report, seven died.

“The number of dentists treated for idiopathic pulmonary fibrosis (IPF) at this Virginia tertiary care center was about 23 times higher than expected,” Dr Randall Nett, the lead author of the study and a medical officer with the US Public Health Service, told CBS News in an email.