Popcorn workers' lung disease caused by new additive, says US survey


Researchers at the US Centers for Disease Control and Prevention (CDC) have found that a flavouring common in the manufacture of popcorn poses respiratory risks for food industry workers.

Lung disease from popcorn

The ingredient used to produce the flavour and aroma of butter, 2,3-pentanedione (PD), was believed safe for workers involved in the mixing and packaging of microwave popcorn.

PD was introduced to popcorn manufacture after an additive used for butter flavouring, diacetyl, was found to damage the epithelium which protects the airways, in turn causing bronchiolitis obliterans.

Known in the food industry as popcorn workers' lung, bronchiolitis obliterans is an obstructive, potentially fatal lung disease which can require transplant surgery.

Now, according to a report in the American Journal of Pathology by the CDC's National Institute for Occupational Safety and Health, PD has been found to produce similar effects to its predecessor.

"Our study demonstrates that PD, like diacetyl, damages airway epithelium in laboratory studies," said the Institute's chief investigator Dr Ann F Hubbs. "This finding is important because the damage is believed to be the underlying cause of bronchiolitis obliterans.

"Our study also supports established recommendations that flavourings should be substituted only when there is evidence that the substitute is less toxic than the agent it replaces."

Dr Hubbs' team exposed laboratory rats for 6 hours to various concentrations of PD, similar concentrations of diacetyl and filtered air.

Lung, brain and nasal tissue examinations were conducted at different intervals after exposure. At between 12 and 14 hours, the researchers found that PD had caused respiratory epithelial injury, similar to the effects of diacetyl, in the upper nose.

The team also determined that PD exposure caused in the olfactory neuroepithelium 2 forms of cell death, necrosis and apoptosis, along with the activation of a protein which contributes to the death of cells, caspase 3.

Dr Hubbs noted that the study is a reminder of how a substance historically consumed with no apparent sign of toxicity can prove to be hazardous on closer analysis.

"It suggests several intriguing potential mechanisms for the toxicity of inhaled volatile a-diketones, reveals mRNA changes in the brain, documents olfactory neurotoxicity, and clearly demonstrates that the remarkable airway toxicity of diacetyl is shared with its close structural relative, PD," Dr Hubbs concluded.

Popcorn workers' lung disease is known to strike personnel on microwave-popcorn packaging lines. Although a typical victim might be a physically active non-smoker with no chest symptoms, inhalation of diacetyl – and now, according to researchers, PD – can lead to coughing followed by aching muscles, night sweating and shortness of breath.

As symptoms of popcorn workers' lung disease become more severe and the condition sets in, a lung transplant often becomes an urgent necessity.

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