"Nuking" Food: Still a Metaphor

The Paper of Record, unafraid to tackle the really important questions, today addresses the perennial favorite: Is it dangerous to stand near a microwave oven?

You'll be happy to know that the answer is still "No." I would've preferred "No, you dolt," but you take what you can get:

Although microwave ovens can in fact leak radiation, the levels that might be released are fairly minute.

According to the Center for Devices and Radiological Health, a unit of the Food and Drug Administration that regulates microwave oven safety, every microwave that reaches the market must meet a requirement limiting the amount of radiation it can leak in its lifetime to five milliwatts per square centimeter at roughly two inches away from the oven. According to the center, that is far below the levels of radiation that have been shown to harm humans.

My only real objection to this is that it gives the false impression that the "radiation" from microwaves is the same as the "radiation" from atomic bombs and the like. I mean, technically, they are the same, in that both microwaves and gamma rays are forms of electromagnetic radiation, but then, so is visible light, and you never hear people asking about whether they're getting "irradiated" by standing too close to a light bulb.

The "radiation" that people worry about causing cancer and the like is generally gamma radiation, with photon energies on the order of MeV, or a 1,000,000 electron volts (a small but convenient unit of energy). These photons have wavelengths of about a thousandth of a nanometer, which is smaller than the size of an atom. They're a significant health hazard because they can pass through large quantities of ordinary matter without stopping, and when they do interact with atoms and molecules, they tend to knock electrons loose from whatever they hit, which triggers all sorts of unpleasant chemistry. When gamma rays ionize atoms and molecules inside cells, they can do a great deal of damage, sometimes killing the cell outright, sometimes causing mutations that can cause the cells to become cancerous.

The "radiation" in a microwave, on the other hand, is, well, mcrowave radiation. Microwave photons have an energy of around 10 μeV, or 0.00001 electron volts. For those playing at home, that's eleven orders of magnitude less than the energy of a gamma-ray photon.

These are so far apart that they're hardly comparable. Microwaves are easy to contain and direct where you want them, while gamma rays pretty much go where they damn well please. Gamma-ray photons can blast atoms apart, while microwave photons just sort of jiggle molecules around (which is how they heat food).

High levels of microwaves can lead to damage, basically by cooking flesh. "High levels," in this case, means something on the order of 100 W, roughly what's in your microwave oven. High levels of gamma radiation can cause cellular damage leading to an increase in cancer risk. This occurs at much lower power levels-- this handy radiation FAQ suggests a 5% increase in cancer from a dose of 1Sv worth of radiation exposure, which this page suggests would require something like 1011 gamma-ray photons at 1 MeV. If you got that entire dose in one second, that would correspond to about 0.03 W.

These types of radiation are not remotely comparable in terms of health risk. While I'm glad that the Times took the time to tell people that microwave ovens are no threat, I wish they had spent a paragraph or so explaining that all radiation is not created equal.

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explaining that all radiation is not created equal.

...except for the velocity in a vacuum....

(Unless you want to include particle radiation.)

-Rob

This is an argument that I lost, for the sake of domestic peace, in the early days of marriage. No matter how many links I offered up explaining the difference between ionizing radiation and (shielded) microwaves, it just didn't matter....

All types of electromagnetic radiation can cause genetic changes at the cellular level. The question is what damage can occur at very low levels of exposure and how long does it take? This question has been debated before with few useful conclusions. It is a fact; the lower the level of exposure the less damage that can occur at any one given point in time. What is not well know is the accumulative damage of exposure to low levels over longer periods of time; like a lifetime. Radon gas radiation exposure for example is known to cause cell damage (resulting in cancer) over a long period of time (years) from very low levels of exposure. How many nonsmoker deaths from lung cancer, for example, from unknown sources, have to occur before we realize that even low levels of exposure can cause serious problems over very long periods of time? This will not prevent anyone from living in their radon contaminated home, breath radon air, use cell phones, microwaves, television sets, or computer monitors, etc., but it is good to be aware of the exposures we present to our bodies. At very low levels we may be able to outlive the damage, until we die of old age. I always wonder when I get near a megawatt television transmitting antenna what is the radiation doing to my body. Usually more damage occurs from higher frequency radiation but the level and time of exposure has to be considered.

Trust me on this: You are nowhere near the most annoyed person on the planet over the periodic microwave scares.

Trust me.

By John Novak (not verified) on 10 Jul 2007 #permalink

Microwave ovens work at 2.45 GHz. Many cell phones work at 1.8 GHz. WLAN or Wi-Fi works (at least some systems) at 2.5 GHz. There is a difference in power levels here, but also in the duration of exposure. At least the comparison of frequencies used may in some cases help the unfortunate person understand something of the non-problem.

The "radiation" that people worry about causing cancer and the like is generally gamma radiation, with photon energies on the order of MeV, or a 1,000,000 electron volts (a small but convenient unit of energy). These photons have wavelengths of about a thousandth of a nanometer, which is smaller than the size of an atom.

Didn't you just have a blog post indicating that people are also worried about cancer from ~300nm radiation?

Didn't you just have a blog post indicating that people are also worried about cancer from ~300nm radiation?

Good point.
But again, probably 80% of the time you hear the word "radiation," they really mean "high-energy radiation from nuclear decay." Which is vastly more dangerous than anything that comes out of your microwave oven.

Many cell phones work at 1.8 GHz. WLAN or Wi-Fi works (at least some systems) at 2.5 GHz.

And this is why people are also scared of getting cancer from their cell phones.

In our town a few years ago there was a statistically insignificant cluster of leukemia cases near an overhead power line, radiating energy at an awe-inspiring 60 Hz. Nobody wanted to listen to me about energetics (the victims continued to bask in front of their fireplaces and read by incandescent and fluorescent light). It was sad because I knew one of the kids. But the parents, goaded on by an alarmist organization, really made a big stink of it. I can sympathize, but I blame the abysmal level of science ed here (and it is in a bedroom town for Yale faculty!) It does get discouraging.

Back in the day, I measured the temperature of the universe, via the cosmic background radiation. The peak is about 1mm wavelength. We have been bathed in this for years (like 10E10 years). 60 Hz is like 5E9 less energetic (forgive me if my envelope in in error). Doh?

Just give 'em the SAT version:
gamma ray:microwave as bullet:ping pong ball...

But this doesn't answer the question that troubles me at all! Does exposure to the radiation from microwave ovens increase my susceptibility to mind control? That's what I'd like to know. At least, I think it is.

You know what? I'm not sure what I was saying.

js, add another layer of tinfoil. That'll take care of the high-intensity mind control rays too.

I recommend looking up the scientist who studied this problem for the wireless industry from 1993-1999, Dr. George Carlo. After he found significant problems with cell phones, he was dismissed, and his research ignored. There is a huge coverup going on here for the sake of profit, one that will make tobacco, asbestos and lead seem trite in comparison.
Two good sources of information: www.safewireless.org and www.mast-victims.org

Note that these are INDEPENDENT sites and not funded by the industry. Don't trust anything the industry tells you - they're not concerned about your health.

By stan mrak (not verified) on 11 Jul 2007 #permalink

VJB:

Orange or Woodbridge? (My wife's parents live in Orange, and in fact the right of way for the overhead power lines runs across the back of their property...she and her three siblings grew up playing under the things with no ill effects).

It *is* important to realize that UV is ionizing radiation because the photon energies get into the 3 eV territory where they can produce free radicals. This mechanism for causing cancer, shared by chemicals that also produce free radicals, is well understood. Those arguing that radio waves can produce cancer have the burden of proposing a biological mechanism in addition to proving that correlation does indeed imply causation.

"Larry Dodd" makes some interesting claims about low levels of ionizing radiation that remain controversial because the data are ambivalent. There are some data [e.g. Cohen in Health Phys. 68, 157 (1995)] suggesting that low levels of radiation can reduce cancer risk, presumably by stimulating the repair mechanisms that clean up free radicals produced by many cellular processes. There are also data on the other side, all with large uncertainties. BEIR chose the linear no threshold model to err on the side of safety in the face of ambiguous data, but to assert that low doses *are* harmful is a stretch.

"Dodd" also asserts that intensity makes up for low photon energies, a claim that contradicts the physics of the photoelectric effect.

By CCPhysicist (not verified) on 11 Jul 2007 #permalink