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When it comes to microwave popcorn, best to emulate Bill Clinton: Don't inhale.
Last month a jury in Colorado awarded 59-year-old Wayne Watson $7.2 million from three companies for damages caused by microwave popcorn. The reason? In 2007 Mr. Watson contracted a rare but serious lung disease, in which inflammation and scarring block airways, severely restricting air flow, as in Watson’s case, by as much as 60 percent. This disease, called bronchiolitis obliterans, is irreversible and, when it becomes life-threatening, the only treatment is a lung transplant.
What’s the popcorn connection? As Watson's lawyers successfully argued, their client's bronchiolitis oblitereans had been caused by eating and, more specifically, inhaling the vapors from microwave popcorn.
Sound surprising, far-fetched? Another example of our overly litigious society in action? Not so much. In fact the disease Mr. Watson contracted is colloquially known as "popcorn lung." In 2000 the National Institute for Occupational Safety and Health (NIOSH), an arm of the Centers for Disease Control, had begun investigating eight former workers at a microwave popcorn facility in Missouri who had developed bronchiolitis obliterans; that intensive research traced the cause of the disease back to the facility (hence the name popcorn lung) and specifically to exposure to a compound commonly used as an artificial flavoring agent: 2,3-butanedione or diacetyl. (More here and here.)
The Missouri problems were not isolated (see here, here and here) and in 2004 NIOSH issued a health alert (PDF) for workers exposed to flavorings, complete with steps to protect workers’ health. That was followed in 2011 by a draft guidance document suggesting exposure limits for workers.
What’s in the Bag?
The problem with microwaving popcorn is that the heating process vaporizes the diacetyl in the bag. In Watson’s case, it wasn't just the decade-long, two-bag-a-day habit he'd happily developed; he had also "particularly enjoyed inhaling the buttery steam pouring out of a just-opened package." Little did he know that he’d been chronically drinking into his lungs lots of diacetyl, the compound that caused lung disease in those microwave popcorn factory workers.
Read the Label? What Label?
And here’s something else. Even if Watson had known that the "inhalation of butter flavoring chemical mixtures, including diacetyl, has been associated with severe obstructive lung disease popularly known as 'popcorn lung,'" he may well have inhaled deeply anyway because the popcorn labels almost certainly did not list diacetyl as an ingredient, never mind contain any warnings.
On a recent investigative trip to my local grocery store I did not find a single butter-flavored brand of microwave popcorn that listed diacetyl as a flavoring ingredient. (See photos.) The labels read simply: "natural and artificial flavoring." (ConAgra's labeling did indicate that its popcorn contained no diacetyl flavoring, but it failed, however, to specify what it used instead.)
One reason diacetyl is missing from popcorn labels is that listing such ingredients is not a requirement. And the Food and Drug Administration, in its capacity as an overseer of food safety, considers diacetyl to be a food substance "generally recognized as safe." Now, perhaps diacetyl has escaped FDA regulation because its effects come from respiration (not ingestion,) or because the FDA's safety finding was published in 1980, decades before popcorn lung was identified. Since more recent scientific findings on the chemical have come to light the FDA has been asked about revoking the safety finding. Recent correspondence with the FDA indicates that, at the very least, a new review is underway:
We also intend to address the issue of diacetyl-containing substitutes in our response. Although it is highly unusual for the FDA to contemplate food ingredient regulation on the basis of inhalation, we have not ruled out any regulatory option.
Substitutes: A Quick Fix or Another Problem Ready to Pop?
Once it was reported that the health effects from breathing in diacetyl weren't limited to occupational settings, several microwave popcorn manufacturers (see here and here) announced they’d be replacing diacetyl with another flavoring.
And what might that substitute be? Will one disease-inducing compound be traded for another? An animal study published last month in the American Journal of Pathology is not reassuring. The authors, led by Ann Hubbs of NIOSH, found that 2,3-pentanedione, a diacetyl substitute, causes similar damage to lung airways in rats as well as gene alterations in their brains. Kind of reminds one of the discussions around the chemical industry's efforts to find substitutes for flame retardants. Do you think maybe there's a systemic problem here?
Hobbs has underscored the seemingly obvious: "flavorings should be substituted only when there is evidence that the substitute is less toxic than the agent it replaces.”
And on top of that comes more bad news on diacetyl. Writing on another new study in the journal Chemical Research in Toxicology, Swati More of the University of Minnesota and colleagues suggest a possible link between diacetyl (via its impact on a brain protein) and Alzheimer’s disease.
So What's a Popcorn Lover to Do?
As you might guess, popcorn is a hugely popular (and fairly nutritious, high-fiber) snack food in the United States. The National Institutes of Health reports that in 2005 156 million bags of microwave popcorn were popped. In pounds, that’s 39 million. While the microwave popcorn companies fight the damages (seemingly more concerned with aliens in the bags than chemicals) and consumers play a guessing game as to what actually might be in their bags, the crunching and munching goes on.
"Currently, even though there is little to suggest significant risk to normal consumers, a sensible precautionary approach is appropriate. Consumers could take simple precautions to minimize the amount of diacetyl and other chemicals that they breathe... the popped bags should be allowed to cool before they are opened, which will also decrease exposure to vapors."
TheGreenGrok's Simple Microwave Popcorn Recipe: Bag the Bag
Place a covered glass bowl loaded with a layer of popcorn moistened by cooking oil into the microwave for about six and a half minutes on high. (If you try this, be careful retrieving the bowl from the microwave -- it can be very hot.) Add real butter, if so desired. Some tips: I use an inverted dinner plate to cover the popcorn bowl and I like to melt my butter before popping the corn by zapping it in the microwave for 45 seconds on medium power. And here's my new wrinkle: adding salt with the oil before popping to cook in that salty flavor.
The best part? Inhale to your heart's (and lung’s) content.