Popcorn Lung (Bronchiolitis Obliterans)

Popcorn lung is the common name for bronchiolitis obliterans, a disease in which inflammation and scarring narrow or block the bronchioles, the smallest airways in the lungs. The damage is generally permanent. Symptoms include a dry cough, shortness of breath, wheezing, and fatigue, and they often worsen over time. It can be misdiagnosed as asthma or chronic bronchitis.

The American Lung Association explains that the disease was first identified in workers at a microwave popcorn plant who had inhaled the flavoring chemical diacetyl, which is how it became known as popcorn lung. Diacetyl gives artificial butter its flavor and has been used in popcorn, baked goods, and candy flavorings. The Association notes that diacetyl is also found in tobacco smoke and in some flavored tobacco and vaping products. Other causes include certain chemical fumes, some infections, autoimmune disease, and complications after lung or bone marrow transplants.

Popcorn lung has been the subject of lawsuits for two decades. Flavoring plant and popcorn factory workers sued the suppliers of butter flavorings, and some won significant verdicts. Consumers have also sued, though those claims are harder because household exposure is far lower. More recent litigation and public concern have focused on flavored e-cigarettes, since some vaping liquids were found to contain diacetyl or related chemicals. As with other toxic exposure claims, a lawsuit requires a confirmed diagnosis, usually through lung function tests and imaging, plus evidence of exposure.

See the vaping and e-cigarettes entries, and our explainer on class actions versus mass torts.