Seven of the patients were dead, and two more were dying of a rare chronic, progressive lung disease that can be treated but not cured.  It’s estimated that about 200,000 people in the United States have Idiopathic Pulmonary Fibrosis (IPF) at any one time. But the common denominator of a small group of patients at a Virginia clinic over a 15-year period is worrying the Centers for Disease Control: Eight were dentists; a ninth was a dental technician.

The dental professionals were 23 times more likely to have IPF than the rest of the population, the CDC said in its Morbidity and Mortality Weekly Report, released on Friday. Something in their workplace environment may have been poisoning them, investigators said, although they don’t know what. IPF causes scarring of the lungs, according to the report. It can be slowed, but nothing can remove the scar tissue. Over time, the lungs have difficulty getting oxygen to vital organs like the heart and brain. READ MORE