The Unexpectedly Deadly Chemical Responsible For Butter Flavoring

We've all had movie theater popcorn at one time or another. Though theaters offer plenty of other movie snack options, such as candy or ludicrously overpriced chicken fingers, simple popcorn will always rule when it comes to the grand cinematic experience. A big part of that is due to the presence of movie theater popcorn butter, a liquid substance as cloying as it is undeniably and relentlessly compelling.

But if you've had movie theater popcorn in the last decade and a half, you might have noticed that it didn't seem to taste quite as good as it used to. It would be easy to attribute that to simple childhood nostalgia (and most people probably do). But the truth is, it's not your imagination; it does taste different now. 

The reason is because in the mid-2000s, artificial butter flavoring had to change radically, thanks to the presence of a surprisingly dangerous chemical: diacetyl.

Diacetyl causes a condition with a truly horrifying name

Unlike almost every other dangerous food additive you could care to name, diacetyl isn't dangerous if you ingest it — which is why nobody spotted the health concerns surrounding it for a while. Instead, the danger comes from inhaling the fumes produced by the chemical. But who could be inhaling enough diacetyl fumes for it to be a real danger?

Employees of popcorn factories, it turns out. Exposure to excess diacetyl fumes causes scar tissue to accrue in the lungs, leading to the eventual blockage of air flow in a condition called bronchiolitis obliterans — which has since been nicknamed "popcorn lung." 

In the mid-2000s, popcorn production companies saw a wave of successful lawsuits as a result of factory workers suffering from popcorn lung, and the industry soon excised the chemical entirely. This was true not just for artificial movie theater butter liquid but microwave popcorn as well. It makes sense, considering there was one documented case of a consumer getting popcorn lung after eating two bags a day for a solid decade. Movie theaters have since primarily used a new chemical concoction, created in 2011, called Flavacol.

Diacetyl shows up in a lot of unexpected places

Diacetyl isn't banned and is in fact a naturally-occurring chemical. It's produced automatically during the fermentation process of wine and beer and ultimately serves much the same purpose there. The reason some white wines have a particularly buttery flavor is due to the presence of diacetyl. 

It's important to note, though, that you're not going to get popcorn lung from sniffing a glass of Chardonnay. The naturally-occurring form of diacetyl is entirely safe relative to the artificial variety.

Of course, the chemical's lack of illegality has led to some other issues, albeit in a roundabout fashion. In the mid-2010s, diacetyl started showing up as a flavoring agent in e-cigarettes. One study found its presence in 75% of samples tested, and kids as young as 17 started to develop popcorn lung. This is particularly incredible because we know the chemical is safe to eat but extremely not safe to inhale. It seems the FDA's vape regulations came none too soon.