But Really, Can You Stand In Front Of The Microwave?

15:08 minutes

Here’s the microwave in the SciFri office. Credit: Lauren Young

It’s been more than 50 years since the advent of home microwaves. Did you know that this household device uses the same technology as radar? Or that the cooking application was an accidental discovery?

Timothy Jorgensen, an associate professor of radiation medicine at Georgetown University, says he fields more concerns about the safety of microwave ovens than any other kind of device, even though microwave radiation is very different from the ionizing radiation that can cause cancer.

[How to build a UV detector.]

He joins Science Friday along with John Drengenberg, consumer safety director for UL (Underwriters Laboratories), a safety science company that has been testing microwave ovens since their inception. The two discuss the science and safety of nuking our food.

Segment Guests

Timothy Jorgensen

Timothy Jorgensen is an associate professor of Radiation Medicine at Georgetown University in Washington, D.C..

John Drengenberg

John Drengenberg is Consumer Safety Director at Underwriters Laboratories in Northbrook, Illinois.

Segment Transcript

IRA FLATOW: This is Science Friday. I am Ira Flatow. Now I am not sure if I’m telling office secrets out of school, but I got to tell you that a couple of weeks ago our microwave oven at SciFri HQ broke down. Now, right, not really a big deal. Not big news. Except the way it broke down. The way it broke was kind of dangerous.

You know, normally when you open up the door the microwave shuts off. But in this case opening the door turned on the microwaves. Here you found yourself looking, staring into the microwave oven with all these microwaves coming out. And of course it created a bit of anxiety on the team and prompted some other microwave safety questions.

So producer Christie Taylor captured some of those questions and concerns around our office.

ANNIE MINOFF: I opened the door and it turns on, which is weird. But I didn’t really think too much about it. And I just stuck my hand in the microwave while it was microwaving to get my pasta. Then I was sitting at my desk and I’m like, does my hand feel weird?

ALEXA LIM: If it’s cooking chicken, is it also cooking my hand if it is on with my hand in it?

ANNIE MINOFF: But like, what does a microwave do to body parts?

BRANDON ECHTER: Does it mess with my vision? Will it, like, give me brain cancer? I know that microwaves are safe. And I know this is a little irrational. But, you know, I just want to make sure that this broken one isn’t going to, like, kill me.

ELAH FEDER: I stayed away from the kitchen, too. Just in case people like you are going to be using it.

RACHEL BOUTON: How close am I allowed to stand in front of the microwave? Because I like to watch the cheese on my nachos melt.

ALEXA LIM: What is on the door that’s protecting us from it? I mean, I see like the little meshy pattern. That’s all that’s needed?

RACHEL BOUTON: I always wonder if all the microwave food I eat is going to give me cancer the same way everything else is eventually going to give me cancer.

BRANDON ECHTER: Oh God, what if it goes on fire?

ELAH FEDER: I’ve seen insects get microwaved and seem fine. How does that work?

ALEXA LIM: How much actual– is it radiation that we’re getting from the microwave?

ELAH FEDER: Obviously you shouldn’t put your pets in there.

ANNIE MINOFF: I don’t have that many questions about it. I’ve just assumed it was a completely safe and effective mechanism for heating my pasta.

IRA FLATOW: Yeah, there’s that beep. So we had all these questions. And if we had all of these questions, I’m sure you’ve had all these questions about microwave ovens. And even the history of microwaves is really interesting. Because 2017 marks the 50th anniversary of the first domestically available microwave– the Radar Range, which sold for $497 back in 1967. Namely because maybe, I guess, the scientist who worked with radar in World War II accidentally discovered that radar waves could be used to cook food. Another case of serendipity.

And all these years later, even our geeky science folks in our office, me included, have apprehensions about this essential household device. So we’re going to pull in some experts. And here to relate the life and times of the microwave oven and shed more visible light on safety, John Drengenberg, consumer safety director for UL, you know, the old Underwriters Laboratory– a safety science company that’s been testing microwaves since their advent. And they are based in Northbrook, Illinois. Welcome to Science Friday, John.

JOHN DRENGENBERG: It’s nice to be with you, Ira.

IRA FLATOW: Thank you. Timothy Jorgensen, an associate professor of radiation medicine at Georgetown University in Washington. He’s also the author of Strange Glow: The Story of Radiation, out from Princeton University Press later this year. Welcome to Science Friday, Timothy.

TIMOTHY JORGENSEN: Thank you very much, Ira, for that beer.

IRA FLATOW: You’re welcome. First question, for producer Annie Minoff’s sake, is her hand going to be OK after that microwave encounter?

TIMOTHY JORGENSEN: Well, the first thing I would recommend is to get rid of the oven.

IRA FLATOW: It’s gone.

TIMOTHY JORGENSEN: Maybe John can explain how it could go on when you open the door. Because I certainly–

JOHN DRENGENBERG: I agree completely. I agree completely. Throw that away.

TIMOTHY JORGENSEN: The main hazards from microwave ovens come from heating. So you can burn yourself with a microwave oven. So that’s the danger. So if the microwave was, in fact, on and she put her hand in it, she would have felt the heat. And hopefully she would quickly withdraw her hand before she got a burn there. But that’s the main hazard with microwave oven. It’s the burning.

IRA FLATOW: I was saying a few moments ago, the microwave has been in our homes for 50 years, Timothy. I know you have written a bit about how we got it in the first place. And I know the history, because I’ve written a little bit about it. But it was a fortuitous accident involving a radar tube and a candy bar, if I remember correctly?

TIMOTHY JORGENSEN: Yeah, so there was this guy, Percy Spencer, up at Raytheon. And he was a whiz with radar. And he was working on developing radar for the government. And one day he was working with an item called the magnetron, which is what actually produces the radar waves. And so the thing was on. And he noticed that a candy bar he had in his pocket was melting.

And so he attributed it, it must be coming from the microwaves. And so what he did was, he took an egg and he aimed the radar magnetron at the egg and the egg exploded. Then he did something similar with popcorn. And pretty soon he went on to patent that and it became the microwave oven.

IRA FLATOW: But, John, these were not the tiny little ovens that we have today.

JOHN DRENGENBERG: Really, the first ones were gigantic ovens. They were as big as a refrigerator. And in fact, to keep the magnetron– which was the main tube that produces the microwave energy– to keep it cool they had to plumb it with the cold water so it would not destroy the magnetron

IRA FLATOW: So they had them only in big places, maybe steamships– in those days that’s ocean liners and trains, places you could have a 700 pound box sitting with all the plumbing in it.

JOHN DRENGENBERG: It was a commercial device that was used only by restaurants or food facilities of one kind or another.

IRA FLATOW: Well, let’s get our listeners in on it. Because people are going to want to ask questions. 844-724-8255 is our number. You can also tweet us at SciFri. Let’s see if we can answer some of the questions that even our staff was asking. And the number one question I know that I get asked all the time about it is why don’t the microwaves go through the glass? Right, if you’re standing there, what’s keeping them from going through the glass, Timothy?

TIMOTHY JORGENSEN: Well, so the glass has a mesh screen across it with little holes. And those holes are spaced just right so that those ways will not come through. But they’ll just bounce around within the oven. So that’s a protective screen. So you can see through the holes what’s going on in the oven. But the waves are not actually coming out and cooking you. That’s how it works.

IRA FLATOW: So how do you test whether there’s a leak, John? How do you test whether there’s a leak in the microwave door or the oven?

JOHN DRENGENBERG: When we test a microwave oven at UL, we do have meters that can measure the radiation that might come out of the door gasket area or even a ventilation opening. And we test every design to make sure that it does meet the standard for leakage of microwave energy. But most microwaves today are very good and there are very, very few times that we’ve ever heard of anybody getting burned or hurt from a microwave oven.

But consumers have to understand, too, that if you do spill something in your microwave and it runs over the edge of where the door meets the microwave oven, you’ve got to clean that up. If it gets to be a crusty mess there, it could allow microwave energy to escape. So keep that door gasket area very clean with a damp rag. That’s the best safety device that you could have is a damp cloth.

IRA FLATOW: Dr. Jorgensen’s, let’s also talk about when we in the vernacular say I’m going to nuke something in the microwave. There’s no nuclear energy or radiation of that type involved, is there?

TIMOTHY JORGENSEN: No. So it is radiation. But radiation comes in an electromagnetic spectrum. So we have everything from very long wavelength radiation, like AM radio waves that are as long as a football field, all the way down to x-rays which have wavelengths that are one hundredth of the width of a human hair. And the shorter the wavelength, the higher the energy. So microwaves don’t have enough energy to cause biological damage as we think x-rays do. So the whole world of radiation can be divided into two. One is the non-ionizing radiation, which are the microwaves, the radio waves, the cell phone radiation, and things like that. And then there’s the ionizing radiation, x-rays and gamma rays. They have wavelength so short that they can actually rip electrons off of atoms and cause damage. And it’s those things we worry about, the ionizing radiations. The non-ionizing radiations do not damage chemicals. They heat them up. But they don’t damage them.

IRA FLATOW: Now, I understand that the microwaves heat things by shaking specifically water. They like the water molecule and they shake the water molecule.


IRA FLATOW: What is the best thing to put your food in the microwave to most efficiently allow the microwaves in to get to the food?

TIMOTHY JORGENSEN: OK. So obviously, paper bowls and things like that, they don’t have any water in it. They can allow the waves again very easily. You obviously can’t use metal containers because they’ll block the waves. Ceramic will let a large amount of the radiation in. So that’s usually not a problem. But anything that doesn’t have any moisture in it is a good holding vessel for the food items you want to cook.

IRA FLATOW: M’hmm. Let’s go to the–


IRA FLATOW: I’m sorry. Go ahead.

JOHN DRENGENBERG: That very correct. But sometimes now, paper plates, if it’s reconstituted paper, have little metal filings on them that are not perceived by the eye. And that sometimes causes them to look a little burned when you take them out of the microwave oven. It’s something that we hear of every so often. It’s not terribly dangerous. But the fact is, a paper plate that has reused paper– which everybody wants to do, because that’s a very environmentally conscious to do that– but you can have that situation. And also if you put a nice plate in there that might have a gold trim along the edges of some kind, that is something that would cause some problems, too. Because it could heat that gold ring– which is a metal– and it could cause maybe the food to get too hot in certain places.

IRA FLATOW: And people put those take out food boxes with the little metal handle on them, like the Chinese food, in there. And they spark, right? Those little metal parts are–

JOHN DRENGENBERG: They definitely can spark. Especially if they touch the side of the chamber– or the cavity as it’s called technically. And the same is true with aluminum foil. You can get away with it a little bit. But the fact is, once it touches the side of the microwave oven you’ll get gigantic sparks. And we’ve done some research on that at UL. And we can tell you that almost any type of aluminum foil could cause a problem inside a microwave oven.

IRA FLATOW: Let me see if I can get one quick question in from Kansas. Hi, welcome to Science Friday.

SPEAKER 8: Hi. I’ve been waiting 30 years to ask this question. In the 1980s an osteopathic doctor told me that– he said, do not use a microwave oven because it heats the food to too high of a temperature. It kills the enzymes, which is why we eat food. Those are his words. What do you say?

IRA FLATOW: Well, quickly, because I’ve got 30 seconds till the break. So if you can get it then, 30 seconds.

TIMOTHY JORGENSEN: OK. No, the answer is no. The only thing that’s going to destroy food nutrition is if it does get too hot. You can make it too hot by boiling. You can make it too hot in the oven, on the grill, and with the microwave. So don’t worry about the microwaves in that regard.

IRA FLATOW: Stay with this for a few minutes when we come back from the break. So stay with us. We’ll be right back. And talk more a bit about microwaves.

You’re listening to Science Friday. I’m Ira Flatow. We’re wrapping up a little segment about the microwaves, microwave ovens, with John Drengenberg and Timothy Jorgensen. Now, John, at UL where you are, I understand that you test the microwaves with a baked potato. Is that correct?

JOHN DRENGENBERG: Oh, absolutely. That’s one of the many tests we do on a microwave oven. The leading cause of fire is inside a microwave oven is popcorn and potatoes. And we saw that there was an incident– a lot of incidents– of fires inside of microwave ovens. And then we did the research on it. We found out that it was the popcorn and the potatoes. And we thought what kind of a test could we develop that would help that problem?

We came up with what we call the cavity fire containment test. And the way we do it is, we put potatoes inside a microwave oven on the turntable, a number of potatoes, and we heat them until they’re cooked. We heat them until they get very dry, they turn black, and ultimately little sparks appear across the peel and they burst into flame. And then you’ve got a flaming merry-go-round inside. But before we do all of that, we cover the microwave oven with a material called cheesecloth, which is our fire indicator. If that fire inside the microwave oven gets to the cheesecloth, it’s a failure. If it doesn’t it’s, OK.

It doesn’t sound too OK when you know that you’ve ruined your microwave oven. But the reality is, it saves your house. And it saves your family from a possible terrible disaster. And that’s simply because very often we’re in such a hurry we push all the wrong buttons on the microwave oven and then run away from it. Nobody wants to sit there and watch the food cook. And we find that people, as hard as they try, they might set it for three hours or some huge amount of time and leave the potatoes or whatever is in there alone. And then you can get a fire. So we just want it to be contained so it doesn’t spread to the bread wrappers or the paper towels on your kitchen counter.

IRA FLATOW: One last question, Dr. Jorgensen. Why, why are people so fearful of the microwave?

TIMOTHY JORGENSEN: Well, I think it’s largely because you can’t see it. You can’t smell it. You know it’s there. You see it before your eyes what it’s doing to food. And it kind of mystifies people, you know? And the other thing, it’s a man-made type of radiation. And people tend to be more worried about man-made types of radiation rather than cosmic radiation from space or radon from the soil. For some reason, people are more worried about the radiations that we make than the radiations that we counter in the environment, I think.

IRA FLATOW: All right. We could talk about this for quite awhile. Because there’s so much fun you can do in a microwave. Just be safe when you do that stuff. John Drengenberg, consumer safety director for UL, based in Northbrook, Illinois. Timothy Jorgensen, associate professor of radiation medicine at Georgetown University in Washington DC. Have a great weekend. Thanks for taking time to be with us today.


JOHN DRENGENBERG: It’s our pleasure.

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About Christie Taylor

Christie Taylor is an associate producer for Science Friday. Her day involves diligent research, too many phone calls for an introvert, and asking scientists if they happen to have an audio recording of their research findings.

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