Clinical Bronchiolitis Obliterans in Workers at a Microwave-Popcorn Plant

Bronchiolitis obliterans results in irreversible obstruction of the small airways and has known environmental and occupational causes. An investigation was initiated at a plant that produces microwave popcorn after signs and symptoms of bronchiolitis obliterans developed in eight employees. Among current workers at the plant, those exposed to high levels of diacetyl (2,3-butanedione), the principal additive that is used to give the popcorn its butter flavor, had more than three times the expected rate of airway obstruction and more than twice the expected rate of cough. There were strong relations between the degree of airway obstruction and the level of exposure to diacetyl. Occupational exposure to a substance in microwave popcorn can lead to severe airway obstruction. In May 2000, eight persons who had formerly worked at a plant that produces microwave popcorn were reported to the Missouri Department of Health to have bronchiolitis obliterans. 1 , 2 These workers had become ill during the period from 1993 to 2000, while employed at the popcorn plant, and none had reported an incident of presumed overexposure that preceded their symptoms. Four had worked in the room where microwave-popcorn flavoring agents were mixed, and four had worked only in the microwave-popcorn packaging areas. On the basis of these cases, we conducted medical examinations and environmental surveys of workers employed at the . . .