Bronchiolitis obliterans first emerged as a threat in 2000, when the National Institute of Occupational Safety and Health was called to a southwest Missouri popcorn plant to investigate lung illnesses among workers.
Investigators linked the disease to a chemical named diacetyl, used to impart the taste of butter in popcorns.
The disease sickened nearly 200 workers and killed at least three.
"Now we've got cases of bronchiolitis obliterans among workers in other plants that use flavorings and in plants that make the flavorings," said Dr. Kathleen Kreiss, chief of the field studies branch of NIOSH's division of respiratory disease studies.
The disease causes inflammation and obstruction of the small airways in the lung by rapid thickening or scarring. The irreversible condition is progressive and often fatal without a lung transplant.
While NIOSH and the Occupational Safety and Health Administration want to intensify investigations, agency leaders believe enough is being done in its repect.
More than 150 former popcorn plant workers have sued companies supplying or making the butter flavoring.
