Do You Risk Popcorn Lung When You Make Microwave Popcorn?

That bag of microwave popcorn may smell good, but it's best to let the bag cool before you open it.


That bag of microwave popcorn may smell good, but it's best to let the bag cool before you open it.

“Popcorn lung” is an irreversible scarring of the smallest airways in the lungs. It’s caused by inhaling vapors of a buttery-tasting chemical that some manufacturers used to add to their microwave popcorn.

Diacetyl is a natural compound found in cheese, butter, yogurt, and wine. It’s not harmful when swallowed, but it can damage the lungs if large amounts are inhaled. Nearly all “popcorn lung” victims worked in popcorn or flavoring manufacturing facilities, where they breathed in the chemical every day. The most severe cases needed lung transplants.

Several consumers also claim to have developed popcorn lung, including a middle-aged man in Colorado who inhaled the buttery steam from the two bags of popcorn he microwaved every day for 10 years “because it smells good.” He was originally awarded $7 million, but after the supermarket chain that sold him the popcorn appealed the decision, he settled out of court.

Popcorn lung and the future of microwave popcorn

“Generally, flavor manufacturers have reduced the amount of diacetyl they use, and, in some instances, diacetyl has been replaced with other, similar flavoring substances,” says John Hallagan of the Flavor and Extract Manufacturers Association.

In fact, all the major microwave popcorn manufacturers we contacted said they no longer use diacetyl. Many have  switched to supposedly safer ingredients. But studies indicate that at least one of these substitutes, which is chemically similar to diacetyl and called 2,3-pentanedione, may be just as damaging to the respiratory tract.

How can you tell if your favorite microwave popcorn does or doesn’t have diacetyl or one of its substitutes? You can’t.

“FDA food-labeling regulations don’t require the specific declaration of individual flavoring substances,” notes Hallagan, “so butter-flavored microwave popcorn labels will simply list them as ‘natural,’ ‘artificial,’ or ‘natural and artificial’ flavors.”

The bottom line on microwave popcorn

“If you eat butter-flavored microwave popcorn and want to lower any potential risk of inhaling flavoring compounds,” says Kathleen Kreiss of the Centers for Disease Control and Prevention (CDC), “allow the bag to cool before you open it, and use a kitchen exhaust hood if you have one.”

How to buy microwave popcorn: look for 94% fat free

By following the tips above, you can reduce your risk of popcorn lung, but you still need to watch out for popcorn that’s high in salt and saturated or trans fat.

You can quickly narrow down your search for a good microwave popcorn by starting out with brands that are labeled “94% Fat Free” or “No Oil.” That will keep a 5-cup serving at around 100 to 150 calories and just ½ gram of sat fat.

Avoid trans fat. Some microwave popcorns still use partially hydrogenated oil, the source of artificial trans fat. Look for brands—like ACT II, Newman’s Own, most Orville Redenbacher’s, Pop Secret 94% Fat Free and Light, Pop Weaver, Quinn, Trader Joe’s, and Whole Foods—that don’t contain partially hydrogenated oil.

Instead of trans, most microwave popcorn companies rely largely on palm oil. That can make the saturated fat climb. Look for popcorns with no more than 1 ½ grams of saturated fat per 5 cups.

Look for less sodium

Once you’ve got a brand lower in saturated fat, check the sodium. Popcorn tastes just fine unsalted or lightly salted. If you want some salt, look for popcorns with no more than 300 milligrams of sodium per 5 cups.

Look for less sugar

Kettle corn—popcorn cooked with sugar, salt, and oil—has been around for well over 100 years. Today, heavier coatings of caramel, toffee, and chocolate are giving kettle corns a run for their money. Cup for cup, candy-coated popcorns have about triple the calories of regular popcorns. Instead, look for brands with fewer calories and less added sugar. Angie’s Boomchickapop Lightly Sweet Popcorn, for example, has just 150 calories and 1 ½ teaspoons of sugar in 4 cups.