According to the National Institute for Occupational Safety and Health (NIOSH), workers at microwave popcorn factories who have been exposed to vapors from artificial butter flavoring which contain the chemical diacetyl are at risk for lung disease. There is concern that workers at other snack food factories may also have been exposed to this chemical, and be at similar risk.
Workers have alleged respiratory conditions resulting from exposure, including asthma, bronchiectasis, chronic bronchiolitis, chronic obstructive pulmonary disease, and emphysema. However, the most significant claims to date involve bronchiolitis obliterans, a potentially life-threatening condition that involves the blocking of bronchial passages in the lungs as a result of chronic scarring, and that does not respond to normal asthma medication.
Workers with this condition may be able to pursue workers' compensation relief.
Some law firms are have brought product liability claims against manufacturers of butter flavoring, on the basis that they knew or should have known that the product was hazardous, and that they failed to provide adequate warnings about the chemical. International Flavors & Fragrances, and its subsidiary, Bush Boake Allen, Inc., have argued that these claims are without merit and that the butter flavoring they have produced is not to blame for the workers' medical problems.
Some juries have rejected the manufacturers' claims with one jury awarding $20 million dollars to a worker whose bronchiolitis obliterans necessitated a lung transplant, and another awarding $7.2 million to a consumer who claimed that his lung ailment resulted from his frequent preparation and consumption of microwave popcorn.
Many manufacturers have stopped using diacetyl in their artificial butter flavoring.