Microwave Popcorn Lung Prevention Rules Expanded by OSHA

Federal safety regulators say that some substitutes for the chemical diacetyl, believed to cause a condition known as microwave popcorn lung disease in food manufacturing workers, may also be linked to the potentially deadly ailment. 

On Monday, the Occupational Safety and Health Administration (OSHA) expanded its National Emphasis Program (NEP) on Microwave Processing Plants to limit worker exposure to 2,3-pentanedione, which they say may have similar respiratory risks as diacetyl. The expanded NEP also places exposure limits on 2,3-hexanedione and 2,3-heptanedione, which are chemically similar to 2,3-pentanedione and diacetyl. All of the chemicals are known as alpha-diketones.

Diacetyl is a food additive that was once used to give microwave popcorn and some other foods their buttery smell, but it has been linked to bronciolitis obliterans, a respiratory condition more commonly known as popcorn worker’s lung.

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The microwave popcorn industry turned away from the additive once its links to popcorn lung disease became widely recognized and have used a variety of substitutes to duplicate its effects.

The changes in the NEP affect all microwave popcorn processing and manufacturing facilities. OSHA decided to expand the NEP after studies by the National Institute for Occupational Safety and Health (NIOSH) tested 2,3-pentanedione and found that rats began to suffer airway degeneration, cell death, necrosis, white blood cell inflammation and nasal problems hours after being exposed. The study determined that the chemical damages airways in the same manner as diacetyl.

According to NIOSH’s findings, 2,3-pentanedione, 2,3-hexanedione and 2,3-heptanedione are less water soluble than diacetyl, which could mean that they penetrate deeper into the lungs and could have an even greater toxicity than diacetyl.

Microwave popcorn lung is characterized by the scarring and inflammation of small airways, known as bronchioles, which leads to diminished lung capacity and breathing problems. The disease is irreversible and severe cases may require lung transplants and can lead to death. OSHA took action and put the NEP in place in 2007 after a number of workers suffered permanent lung injuries and in some cases died due to popcorn lung disease.

More than 300 popcorn lung disease lawsuits have been filed nationwide, with most of those coming from employees of popcorn manufacturers. However, a growing number of popcorn consumers have been diagnosed with the disease and have filed lawsuits against companies that manufactured or used the flavoring.


  • BugtussleJanuary 25, 2011 at 5:43 pm

    Misleading headine. OSHA didn't expand any rules -- all they did was slightly expand a inspection program "designed to identify and reduce or eliminate exposures to butter-flavoring chemicals used in microwave popcorn manufacturing facilities." Instead of measuring expoures to just one chemical during those inspections, now they're measuring four of them.

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