Workers at the plant developed bronchiolitis obliterans, a type of irreversible lung damage thought to be caused by diacetyl, a chemical in the butter flavoring, the workers claimed. They inhaled it while mixing and packaging popcorn, according to the National Institute for Occupational Safety and Health (NIOSH).
NIOSH began investigating the popcorn maker in August 2000 after a doctor saw six patients with the disorder at once, four more than he had seen in his entire career, all from the same small area of Missouri.
Doctors who investigated for NIOSH said the affects appear to be limited to workers who inhaled large amounts of the flavoring vapors wafting from large vats, adding that there is no danger to consumers of the popcorn.
Four of the workers need lung transplants and a further 21 of the plant’s 117 workers show signs of lung problems, the cause of which is still under investigation.
Employees working in affected areas of the plant are now wearing masks, while the company has engineers looking at long-term solutions. They include sealing the vats so that the vapors are not released into the workplace.
The 16 also have filed a class-action lawsuit against New York-based International Flavors and Fragrances, which makes the flavorings. The plaintiffs are seeking unspecified damages.