In 2000, NIOSH conducted an investigation of exposures at a
microwave popcorn manufacturing plant in Missouri. Public health
officials contacted NIOSH because a cluster of former employees
of the facility had developed a rare lung disease called
bronchiolitis obliterans. The majority of employees diagnosed
with bronchiolitis obliterans had been exposed to mixtures of
butter flavoring chemicals. Evaluations of employees working in
the plant revealed high rates of both respiratory symptoms and
abnormal lung function.1 The investigation concluded that there
was "a risk for occupational lung disease in workers with
inhalation exposure to butter flavoring chemicals".2
Investigations of other workplaces have also shown that
employees that use or manufacture certain flavorings have
developed similar health problems. Because many of the cases
have been associated with popcorn manufacturing plants, the term
"popcorn lung" has often been used to describe the respiratory
symptoms and fixed obstructive lung disease seen