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This might be an odd question, but I often take a sandwich or fruit to eat while waiting for the airplane. This means that my food goes through the security x-ray machine.

I don't understand much about radioactivity, so I was wondering: Is it safe to eat that food right after going through the security machine? or suffer harmful mutations that can affect ones health? Can it keep some latent/cumulative radioactive effect?

Bananas, by nature have a very low level of radioactivity. Does it get increased, for example?

Can I safely eat the food that goes through the x-ray machine after the security check?

nsn
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5 Answers5

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Is it safe to eat food, drink beverages, use medicine, or apply cosmetics if any of these products have gone through a cabinet x-ray system?

There are no known adverse effects from eating food, drinking beverages, using medicine, or applying cosmetics that have been irradiated by a cabinet x ray system used for security screening.

The radiation dose typically received by objects scanned by a cabinet x-ray system is 1 millirad or less. The average dose rate from background radiation is 360 millirad per year. The minimum dose used in food irradiation for food preservation or destruction of parasites or pathogens is 30,000 rad.

For more detailed information on radiation used for food inspection or food treatment, see Title 21 CFR 179, www.FoodSafety.gov, contact FDA’s Center for Food Safety and Nutrition, or contact the United States Department of Agriculture Food Safety Inspection Service.

Souce: The US Food and Drug Administration Home Page (see Question 8)

waka
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    Good reference! It should be pointed out that the 30,000 (thirty thousand) rad used to preserve food is actually 30,000,0000 (thirty million) millirad, so your food has likely already been exposed to thirty million times more radiation than it gets from the X-Ray machine. – Sam Skuce Jun 12 '18 at 14:55
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    @SamSkuce Yes, but which food manufacturers actually do this? Plus this presumably wouldn't apply to whole-foods (only processed). – Cloud Jun 12 '18 at 15:11
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    @Cloud It could apply (and possibly only applies) to non-processed foods (provided you don't consider the irradiation itself "processing"). The FDA's list at https://www.fda.gov/Food/ResourcesForYou/Consumers/ucm261680.htm only lists 'non-processed' foods. 'Processed' foods probably wouldn't need it. – owjburnham Jun 12 '18 at 16:00
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    This is actually missing the point, in a bad way. It assumes that food which has been radiated by 1 millirad somehow carries that one millirad of radiation outside the X-ray scanner. That's not how radiation works. Yes, there's such a thing as activation, where radiated materials become radioactive themselves, but unless you're radiating uranium or plutonium with neutrons that's a limited effect. There's virtually no activation of food by X-rays, so you'd be looking at microrads at most, not millirads – MSalters Jun 13 '18 at 08:11
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    @MSalters: It says "it recieves a certain amount which is significantly less than what it has been exposed to by background radiation", which isn't the same as saying "it carries this radiation outside". – waka Jun 13 '18 at 08:26
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    @waka: Yes, that's exactly my point. It's talking about an irrelevant radiation amount (inside scanner), which is independent from radiation outside the scanner. – MSalters Jun 13 '18 at 08:55
  • @SamSkuce the example that was always used when I learnt about this in my Physics classes was fresh strawberries. They go off primarily due to the bacteria on them breaking them down. Radiation treatment typically gives them roughly an extra week of shelf life with no chemicals used, and no harmful effects remain. This is why "pick your own" strawberries don't last as long as ones bought in a shop (though those in the shop may be older when you buy them, so lifetime in your fridge may be roughly the same). http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/26/037/26037019.pdf – Baldrickk Jun 13 '18 at 09:04
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    @MSalters: But the answers says: "The radiation it recieves inside the scanner is less than what it recieves outside". I think it's safe to assume that they are also saying "and thus the radiation it recieves inside the scanner will most likely not affect the food in a negative way". At least that's how I understand it. – waka Jun 13 '18 at 13:02
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    @waka: You understand it wrong, but I'm not blaming you. I am criticizing the answer, for misleading you and others. We're not worried about damage done to the sandwich. It's already dead, it doesn't matter how much radiation goes through it, whether from background radiation or from the scanner itself. Both numbers (1/scan and 360/year) are irrelevant. – MSalters Jun 13 '18 at 14:12
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    @MSalters I'm pretty sure it's harmful to eat plasma, so I don't see how dose is irrelevant. – Fax Jun 14 '18 at 14:53
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    @MSalters: I'm really, really confused where you pulled that from. Exactly which sentence in the answer "assumes the food which has been radiated somehow carries that radiation outside the X-ray scanner"? I don't even see a hint of that in the answer. As far as I can tell the answer's logic is literally "we add < 1% on top of background radiation so common sense says there you shouldn't expect a problem in this case even if you thought too much radiation was somehow a problem". – user541686 Jun 15 '18 at 20:54
  • @Mehrdad: The answer talks about the dose received inside the scanner. Who cares? It might be 1 millirem, it could be 1 kilorem. As long as the radiation stays inside the scanner, it can't reach me, and it can't harm me. That makes it incomparable to background radiation, which does reach me and does harm me. – MSalters Jun 17 '18 at 20:06
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    @MSalters: I mean maybe you'd worry that it might alter the food chemistry... – user541686 Jun 17 '18 at 20:08
  • @waka The question is not concerned with the damage done to the consumption, it is concerned with the damage done to the consumer. The question assumes little to no understanding of radiation, hence answering what dose of radiation the consumption receives does not (fully) answer the question (and might mislead the uninformed reader); what dose of radiation might the consumer expect to receive? And might one expect other adverse effects? –  Jun 18 '18 at 18:41
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There is

  • radiation that can only heat,
  • radiation that can additionally ionize,
  • and radiation that can actually make stuff radioactive.

XRays are the second kind, ionizing radiation, meaning they may alter some molecules (i.e. the arrangement of atoms), but will not affect the atoms themselves(so no radioactivity is created).

The altering of molecules may also happen to the DNA molecule, which is why XRays are kept to a minimum. So the apple sent through the machine might get a mutation, but the chance of that being a problem to the apple are remote, and the mutated apple being a problem to you is virtually nonexistent. Sending old school films through an old school XRay might be a problem for the film (film is coated with molecules that are easily altered, because detecting (visible)radiation is it's job, and old XRays used higher power sources).

enter image description here

Your association of XRay machines with radioactivity might come from the hazard sign above, that is sometimes quite prominently displayed on Xray machines.

It simply warns of ionizing radiation, which can, as stated, damage your DNA, thereby giving you cancer, etc, depending on strength. It's popular meaning of "Danger! Radioactivity" came about because radioactive materials emit ionizing radiation (that's actually why it's called radioactive, the ionizing radiation messes with radio-equipment). So Radioactive materials emit ionizing radiation, but ionizing radiation does not produce radioactivity.

bukwyrm
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    Signs on airport X-ray machines claim that they're safe for photographic film up to 800 ISO (as I recall). Everyday photographic film was mostly 400 ISO and below. – David Richerby Jun 12 '18 at 16:27
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    I think the concern is not so much with mutations to the apple's DNA (you are probably not planting the seeds to grow more apples anyway), but rather with changes to the molecules and bonds, which could, potentially, modify them to become something toxic. – user102008 Jun 12 '18 at 18:28
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    The apple was a playful excursion because OP mentioned fruit in the question. As the alterations are non-directional, toxins cannot be produced in relevant quantities. – bukwyrm Jun 12 '18 at 19:04
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    Note that the "altering" that X-rays do is almost always "breaking molecules apart". Break the sugar in an apple apart, and you get...usually a different sugar. Break the DNA in a human apart, and you get...a mess. – Mark Jun 12 '18 at 21:36
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    Also note this "breaking apart" is only happening to a handful of molecules. The vast majority of the apple is unchanged. It'll be similar to the amount of fecal residue that was already on your apple... – user253751 Jun 12 '18 at 23:25
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    @DavidRicherby Yes, but the effects are cumulative. Back in the days of silver film if I was flying with film it was to visit her family. That meant three passes through airport security. That 800 ISO that was above normal film now is 266 per pass--and since I was normally carrying some 400 that meant hand inspection despite the screeners that insisted it was safe. – Loren Pechtel Jun 13 '18 at 02:21
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    @user29850 There is magnitudes more fecal matter mass on any apple than mass chemically altered by going through an airport XRay. You underestimate the ubiqiousness of fecal matter, i'd wager. – bukwyrm Jun 13 '18 at 06:31
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    @Mark To be fair breaking the DNA in an apple apart also creates a mess. The apple simply doesn’t live long enough for this to become a problem. – Konrad Rudolph Jun 13 '18 at 09:23
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    @user29850 bacteria inside or on the apple also break it's molecules apart. Your body in the process of digestion breaks apple molecules apart. We actually use "broken molecules" from food in our bodies. I understand your point and it's somewhat valid, though x-ray machines are weak and the number of molecules they break apart are very few and the danger is very very very very very very small at x-ray machine strength. – userLTK Jun 13 '18 at 23:21
  • @bukwyrm: Which makes his point that many orders of magnitude more valid. – Vikki Jun 24 '18 at 17:41
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Yes, you can safely eat food that's been through the X-ray machine (assuming, of course, that it was safe to eat before going through the nuker).

There are two main ways in which something not previously radioactive (such as the food in your luggage) can be made radioactive by electromagnetic radiation (such as the X-rays probing your luggage): photodisintegration and photofission. Photodisintegration requires photons1 with energies in the MeV (megaelectronvolt)2 range, while X-ray luggage scanners use radiation "in the low-to-medium keV [kiloelectronvolt] energy range", a couple orders of magnitude feebler. Therefore, photodisintegration is not a concern here.3 As for photofission, it only occurs to any detectable degree for things that're already prone to fissioning, so, unless you're going to be eating something like plutonium or uranium-235, photofission shouldn't affect your food either.

Conclusion: your food will not be any more radioactive when it comes out of the X-ray machine than it was when it went in.

1: Photons are the basic units of electromagnetic radiation, such as visible light, X-rays, radio rays, ultraviolent rays, infrared rays, etc., etc., etc..

2: An electronvolt (eV) is a measure of energy; it is defined as the amount by which the energy of an electron changes when it moves through an electrical potential difference of one volt. A kiloelectronvolt (keV) equals one thousand electronvolts; a megaelectronvolt (MeV) equals one million electronvolts. The more (kilo-/mega-)electronvolts an X-ray photon has, the more energy it carries, and the more damage it can do with that energy.

3: Some specialised scanners for things like large cargo containers do use MeV-range X-rays, but that isn't a concern for the food in your carry-on luggage.

Vikki
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  • @DavidRicherby I agree with you that adding some background information would enrich this answer and make it more thorough, but I don't agree that it's necessary to include, for OP to get their point across - that X-Rays in carry on scanners are not able to induce radioactivity in food. –  Jun 12 '18 at 16:27
  • You can take out the technobabble entirely and get "Photodisintegration. X-ray luggage scanners use Type A scanning while photodisintegration needs type B scanning. Therefore, photodisintegration is also not a concern here." The information regarding the difference between Type A and Type B is extraneous to understanding the answer, although enriching to know. –  Jun 12 '18 at 16:41
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    "Conclusion: your food will not be any more radioactive when it comes out of the X-ray machine than it was when it went in." But not being radioactive does not mean it's safe to eat. People get poisoned by eating non-radioactive things all the time. – user102008 Jun 12 '18 at 18:29
  • @user102008: True, but the OP was specifically asking about, and I quote, "Can it keep some latent/cumulative radioactive effect?". – Vikki Jun 12 '18 at 23:23
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    Even with photodisintegration, the result would be alpha radiation inside the X-ray scanner: it seems all the disintegration processes are virtually instant. – MSalters Jun 13 '18 at 08:45
  • @MSalters: My point being that, after an alpha (or a proton, or a neutron) has been split off, the remaining nucleus might well turn out to be radioactive. Also, free neutrons, which are themselves radioactive, are also a possible product of photodisintegration, as are protons - but the other part of my point was that airport X-ray carryon luggage scanners simply aren't powerful enough to produce any of these via photodisintegration. – Vikki Jun 13 '18 at 16:20
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    @Sean: I think it's often a good idea to consider how the start of an answer would read if placed immediately after the "title" question. Someone who was wondering if an x-ray would sterilize food and who read "Can I safely eat whatever passes through an X-ray machine" followed by "Yes, you can safely eat foot that's been through an X-ray machine" might get a dangerously wrong impression. Leading off with "food safety is not affected by X-rays" would make clear that food that was safe will remain so, but avoid any impression that food that wasn't safe might be made so. – supercat Jun 15 '18 at 15:34
  • @supercat: Edited to clarify. – Vikki Jun 15 '18 at 19:06
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You might be surprised to know this, but you'll get far more radiation exposure on the airplane than your food gets exposed to in the x-ray machine

As the diagram makes clear, walking through an airport security scanner exposes a person to about the same ionizing radiation dose as eating a banana. Flying from New York to Los Angeles exposes you to roughly the same amount of radiation you'd get from eight dental X-rays — and less than you'd get living in a stone house for a year. And those peanuts that airlines hand out? They're a little radioactive, too.

"Radiation is one example of where people have such a wrong idea about what is dangerous, and are also unaware of its ubiquitous nature," says Barish. "Radiation is all around us. It is in us."

There's this handy chart(referenced above) which shows that neither is particularly dangerous on a dosage scale. If you regularly fly on flights passing over the poles, you might need to be more concerned (but even then we're talking LOTS of flights to get a concerning dose).

So eat up. There's no danger from the x-ray machine.

Community
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Machavity
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    And now I have radioactive stuck in my head. – Wayne Werner Jun 14 '18 at 18:01
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    Re, "walking through an airport security scanner..." The scanner that you walk through is completely different from the scanner that they use to inspect your hand luggage. – Solomon Slow Jun 15 '18 at 17:02
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    Re, "same ... dose as eating a banana." The radioactivity for which bananas are known is due to the potassium that they contain. Any excess potassium that you eat will pass through your system in a matter of hours. The only way that eating bananas can increase the level of potassium in your blood is if your body was starving for it. In that case, the health benefit of getting the potassium that you need far outweighs the risk associated with the radioactivity. – Solomon Slow Jun 15 '18 at 17:08
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x-rays are a form of light, just a frequency that your eye cannot see.

exposing food to xrays, in any amount, will not make the food radioactive, just like shining a very bright light on your food will not make it shine once you turn the light off.

Exposing food to fatal doses of EM radiation (like xrays) is how the US Department of Defense prepares its field rations. This technique has been extensively studied since the 60's by academia and the military alike, and no adverse effects have been found.

Nick
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    Yes, another frequency. A higher frequency. Did someone also mention, that the energy increases with the frequency? And that guns are not dangerous either because bullets thrown at you don't do anything, the same is true for bullets fired from a gun, they just carry a little more energy. But not problem, right? Because bullet is bullet and light is light... or so. – Mayou36 Jun 12 '18 at 19:08
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    Actually, you can make things radioactive by irradiating them with X-rays, but you must use a very high-energy X-ray source: Tens of megavolts. Food irradiation usually is done with a source having an energy of one or two megavolts. – Solomon Slow Jun 12 '18 at 19:50
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    The "no adverse effects have been found" is true in the sense that the irradiated food isn't going to kill you. But there may be adverse effects in the sense that the food no longer contains the bugs that your digestive system thrives on. – Michael Kay Jun 13 '18 at 08:24
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    @Mayou36 Apart from the heavy metals, eating someone that's been shot poses no health risk, and the caliber of the bullet is irrelevant. You completely missed the point of the analogy. – Acccumulation Jun 14 '18 at 19:47
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    @Acccumulation two things: you look at something different. I was arguing, whether the effect on matter can be different or not. And here, you compare it with shining bright light on it: you missed the last decade of physics. A lot of photons (light-particles) with low energy do not result in the same effect on matter as a single, high energetic photon as discovered by Einstein, ~100 years ago. High energetic photons can make something radioactive. And it is not the same as shining bright light on it. – Mayou36 Jun 14 '18 at 20:02
  • @Mayou36 But rather than addressing the claim made, you presented an analogy that was not in any way analogous. – Acccumulation Jun 14 '18 at 20:13
  • @Acccumulation I presented an analogy to cover some part of the claim. Namely that the argument, "x-ray is the same as light (except frequency) and therefore cannot make anything radioactive" does not hold. It is not just like shining bright light on food. I did not say anything about whether it actually makes food radioactive or not or whether this will be dangerous to people (I did not address the second one at all). I just showed that one argument is not valid. Therefore I made an analogy holding for just that one argument. Not the entire answer. – Mayou36 Jun 14 '18 at 20:21
  • @Acccumulation: Unless you're a condor, which have digestive juices strong enough to dissolve lead. – Vikki Jun 24 '18 at 17:47