Cup Noodles recently announced that it’s abandoning its characteristic polystyrene packaging — colloquially called Styrofoam — for a microwaveable paper cup in 2024. The news confused fans online and left them asking a simple question: Haven’t Cup Noodles always been microwavable?
The short answer is no. In fact, you should never microwave disposable foam cups or to-go containers.
Polystyrene Packaging Can Cause Cancer
Although seemingly everyone in the U.S. calls disposable foam takeout containers “Styrofoam,” it’s a misnomer. These containers are actually expanded polystyrene (EPS) foam, a type of plastic that contains styrene.
In 2014, the National Research Council (NRC) found that this chemical is “reasonably anticipated to be a human carcinogen.” Similarly, the World Health Organization (WHO) reclassified styrene from "possibly carcinogenic" to “probably carcinogenic” in 2017.
The problem with microwaving EPS, then, is that it could cause this cancer-causing chemical to leech into your food. That said, there are some forms of EPS that the Food and Drug Administration (FDA) has deemed safe for the microwave, though these packages should have clear microwave-safe labels.
Regardless, consumers should avoid EPS for the simple reason that it’s also terrible for the environment.
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It’s Bad for the Environment, Too
Apart from poisoning humans, EPS is also harmful to the environment, with many cities banning it on ecological grounds.
That’s because polystyrene foam is not biodegradable or recyclable, taking hundreds of years to decompose — if at all. And because it remains in the environment for such a long time, it poses a risk to wildlife that mistake it for food.
“Wildlife, like seabirds, will eat these pieces or feed them to their young, filling their bellies with plastic,” Celeste Meiffren-Swango writes for Environment Oregon. “With stomachs full of plastic pieces, these animals won’t feel hungry and will likely starve to death or permanently injure themselves.”
The Bottom Line: Avoid EPS
At this point, we feel like it should be clear that EPS is pretty nasty stuff. Not only does it likely cause cancer in humans, but it’s also destroying the environment. For those reasons alone, it’s worth avoiding polystyrene completely. But if you have to eat something out of a foam takeout container, transfer it to a bowl or plate before reheating.
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