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Microwave Popcorn Linked to Lung Harm

Rare, Deadly Lung Disease Hits Microwave Popcorn Lover
WebMD Health News

Sept. 5, 2007 -- Inhaled fumes from microwave popcorn may have caused a man's rare, deadly lung disease, a leading lung expert says.

The expert is Cecile Rose, MD, MPH, head of the division of environmental and occupational health sciences at National Jewish Medical and Research Center and associate professor of pulmonary medicine at the University of Colorado School of Medicine.

Rose reported the case in a July 18 letter to the FDA, the CDC, the EPA, and the Occupational Safety and Health Administration. None of these agencies has yet issued a public health alert. The letter became public when published on The Pump Handle web site, a public health blog.

According to her letter, the man complained of a worsening cough and increasing shortness of breath. Lung function tests and imaging studies show he has bronchiolitis obliterans -- obliteration of the tiny airways in the lung.

It's a rare disease, first seen in 1985 in workers in food-flavor factories. In 2002, the disease was seen in workers making microwave popcorn -- in particular, those exposed to a buttery-tasting chemical called diacetyl. There have been many other reports since then, with at least three deaths and many patients awaiting lung transplants.

But Rose's patient had never been exposed to food-flavoring fumes. His only exposure was to the two or more bags of microwave popcorn he consumed every day.

Rose took a team to the man's house and tested the air while microwaving some popcorn. Air levels of diacetyl were similar to those in the area of a microwave popcorn factory where workers were affected.

Many foods other than popcorn contain diacetyl. There's no indication that eating these foods is dangerous. But breathing fumes containing diacetyl appears to be very dangerous.

Microwave popcorn, of course, gives off hot fumes if the bag is opened before the cooked popcorn cools. According to news reports, Rose's patient liked to inhale the aroma of newly popped microwave popcorn. Rose reports that his symptoms stopped getting worse when he stopped making microwave popcorn.

Federal Action Needed

David Michaels, PhD, MPH, associate chairman of the department of environmental and occupational health at George Washington University, runs the Pump Handle blog. A year ago, he petitioned the FDA to stop designating diacetyl as a food "generally recognized as safe" -- that is, an acceptable food.

"The key issue is, are there susceptible populations -- children, asthmatics, people with existing lung disease -- who are at more risk? Are people getting sick at lower exposure levels?" Michaels tells WebMD. "Dr. Rose is a leading lung expert who knows that diacetyl vapors cause lung disease. But will the average pediatrician who sees a child with what seems to be worsening asthma be looking for microwave popcorn exposure?"

Michaels says it's time for federal agencies to act.

In March 2005, the EPA told WebMD that a study of microwave popcorn emissions would be completed in 2005. The study looked at some 50 different microwave popcorn types and batches to identify and measure the compounds emitted during the cooking process.

According to documents obtained by Michaels, the popcorn industry already has seen the EPA study. The EPA now tells WebMD that the study has been submitted for publication and may appear as early as next month.

Meanwhile, four of the leading makers and sellers of microwave popcorn have acted. Con Agra, General Mills, American Pop Corn Company, and Pop Weaver have said they will stop using diacetyl in their products, according to news reports. Their brands include Orville Redenbacher, Act II, Pop Secret, Jolly Time and Pop Weaver.

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