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About 20 people a day end up in American emergency rooms from “microwave oven-related injuries.” A few from microwave popcorn steam, overheated “hair removal wax,” nearly one-a-day from exploding eggs; but most are from overheated water. See, when you boil water on the stove, “bubbles rise from the bottom, and as they burst…, the excess heat is dissipated. Water heated [in] a microwave oven [though may] not bubble,” and so, can get even hotter than normal boiling temperature. Then if you sprinkle in some powder, “tiny air bubbles are carried into the [liquid],” and can expand into steam bubbles, and erupt onto your hand. The FDA warns to be careful when trying to boil water in a microwave—particularly in a “shiny container [or] more than once,” or for too long, or when not letting it cool down a bit first, or when dumping something into it.

Most “microwave-related burns in young children occur” when the child reaches in to grab something hot. Toddlers “as young as 18 months can open a microwave.” So, some public health advocates have recommended that instead of just warning people to let stuff cool first for a few minutes, there should be some kind of door lock that doesn’t let you even open the thing for two minutes after it stops—which kind of undermines the whole point of quick microwave convenience. A better idea may be to just kind of childproof the door, so you have to like turn a knob while pressing a button to pop the door open.

When people express concerns over microwave oven safety, though, they are probably not thinking about exploding eggs or hair wax injuries. They’re concerned about the microwave radiation itself. Microwave oven manufacturers caution people not “to operate [the] oven with the door open.” But, there are interlocking safety switches that should turn it off automatically when you open the door, unless, you’re stuck inside one. God, I couldn’t even read that article.

There is some leakage of microwave radiation, though, during operation. There’s this famous radio telescope scanning the cosmos for extraterrestrial civilizations. “Fast radio bursts” were detected. A sign of “extragalactic” intelligence? Nope, turns out ET was a microwave in the staff cafeteria that the telescope caught when it was just at the right angle, right when someone yanked the door open.

You don’t need a radio telescope to see it, though. A “cheap way of detecting microwave oven leakage is to [just] place a computer monitor next to the oven,” and you can see “disturbances on the screen.” Or, just use the microwave detector you have in your pocket or purse right now: cell phones. Look, if microwaves can leak out, then they should also be able to leak in. The wavelengths are actually quite similar in size, though obviously different intensity between microwave ovens and cell phones. So, stick your phone in the microwave—DO NOT TURN THE MICROWAVE ON, but close the door, and see if you can call it. When you hear it ringing, that’s confirmation that microwave-type radiation can leak in and out.

And indeed, you can just directly measure the leakage during operation—though nearly all within prescribed safety limits. And, once you move the detectors like a foot away from the door, the levels fall nearly to zero, even if there’s like some food particle or something caught in the door seal. Now, the industry will tell you that “there has never been any verified case of [human] injury due to exposure from [radiation] leakage from microwave ovens.” This is from a guy at Raytheon, though, where the microwave oven was invented, after an engineer in a radar lab noticed the chocolate bar in his pocket had melted.

There has been the rare case report of a malfunctioning machine that didn’t turn off when the door was open, and someone burned themselves, but this was after her hand was in there for like a full minute. Raytheon engineers talk about how they “inadvertently” exposed themselves lots of times to open, active microwaves. They get a warm tummy; they feel a little “transient warmth” when they pass their arm in and out of the oven. But, no big deal, they say.

In fact, the same microwaves used in microwave ovens are “the same…used [for] medical microwave diathermy,” which physical therapists use like a hot pack to treat like rotator cuff injuries. Now, making the claim that, “Well, if the medical profession uses it, it must be safe” isn’t exactly the strongest argument, but does help put things in perspective. “When the heating of people is not deliberate,…it [may be] desirable to limit exposure.”

Is that “minor leakage” during operation anything to worry about, though? In other words, are there non-thermal effects of microwaves? If it doesn’t burn you, can it still hurt you? The Soviets thought so, irradiating everyone in the U.S. Embassy in Moscow for decades.

In terms of microwave ovens, though, the only report I could find was from over 40 years ago: a case report of a woman who developed cataracts after using a leaky microwave oven. But, that’s all there was, just this kind of circumstantial evidence correlation. Lots of people get cataracts; lots of people use microwaves; there has to be more that. The only follow-up study I could find was this Turkish study published a few decades later—but, it was on rats.

Now, they did end up finding some superficial eye abnormalities on the rats placed next to the microwave, but they were like right up against the door, and people don’t tend to stick their faces right up to the glass while things are cooking. So, even if the same thing happened to human eyes, this study might be of limited relevance. But, it can’t hurt to stand back from the microwave while it’s on. Otherwise, microwaves should be safe, unless…you drop it on your foot.

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