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"An ordinary radio wave is short - shortwave radio, all of that. The length of the waves are tiny, thousands or millions of little waves to an inch."

Physicist's comments: That's sounds more like visible light, not radio waves. Our eyes detect wavelengths between 400 x 10^-9m (violet) and 700 x 10^-9m (red). This corresponds to 63 thousands of waves per inch for violet light and 36 thousands of waves per inch for red light. The radio waves are much longer - about 3 meters for FM waves, and about 100 meters for short waves.

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This is from the column "Dr. Gott", syndicated by the Newspaper Enterprise Association:

Question: "I've heard a lot about microwave ovens being safe, yet what about the food cooked inside them? Isn't it bombarded with radiation? My doctor clams up and won't give me an answer."

Answer: "Microwaved food is safe. Microwave ovens do not use radiation, such as X-rays; rather, the ovens bombard food with high frequency sound waves. Modern microwave ovens, if used according to manufacturer's directions, are safe. However, there are two caveats. First, with continued use, the seals on ovens deteriorate, allowing a leakage of microwaves during operation...

Physicist's comments: I'll just quote Dr. Barron Arenson, who send this gem in: "OUCH !!"

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In the article "Irradiation could keep mail safe, effects need closer look" by John Fauber, published in the Milwaukee Journal Sentinel and reprinted by the Daily Egyptian, the author wrote:
    "The U.S. mail could go the way of some ground beef, imported produce and personal hygiene products - zapped with bacteria-killing radiation. (...)
    There are two kinds of irradiation being considered for the mail.
    In one, the radioactive isotope cobalt-60 is used to produce a high-energy stream of light particles that bombards the product, penetrating deep enough to kill all bacteria.
    The other type employs electricity to produce a non-radioactive beam of electrons that are shot from an electron gun.

    Irradiation most definitely can kill anthrax spores in mail. (...) A minimum dose of 25 kiloGray would do the trick. A dose of 8 kiloGray is equivalent to 264 million chest X-rays. Fresh ground beef usually receives 4.5 kiloGray."

Physicist's comments: The first problem I have here is with the way the author uses a word "radioactive". The first kind of irradiation mentioned above used to be a standard way of doing a radiation therapy. It uses a radioactive cobalt-60, whose nucleus decays by a beta decay into excited nuclear state of nickel 60,

The half-life for this beta decay is 5.27 years. The excited nucleus of nickel-60 immediately decays into the ground state, emitting two gamma-ray photons, each with approximate energy of 1.2 MeV,

As you can see, the "light particles" used in the irradiation are in fact high-energy photons, i.e. electromagnetic waves, from the nickel-60 deexcitation, as well as electrons from the cobalt-60 decay (the antineutrino produced in the beta decay always escapes without interaction with the material irradiated.)

Hence, it does not make much sense to refer to the electrons produced in the second kind of irradiation as "non-radioactive". Electrons, gamma rays and antineutrinos are just forms of radiation - they are not radioactive themselves. It's the source, cobalt-60 that is radioactive.

My second problem is with the radiation doses. A typical diagnostic chest X ray exposes a person to from 0.05 to 0.3 milliGray (5 - 30 millirems), hence a dose of 8 kiloGray would be equivalent equivalent to from 27 million  -to 160 million chest X rays.

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"Irradiation is a process of using high heat exposure to kill off bacteria, parasites, viruses and other microscopic threats. It essentially sterilizes food. As the nation's largest food producing state, California is most familiar with it, irradiating everything from strawberries to beef steak. It's also common in large fruit producing states, such as Florida, since the process lengthens shelf life."

Physicist's comments: It appears that the reporter confused irradiation with pasteurization. Pasteurized milk is milk that has been heated to 145 F (63C) for 30 minutes, or 161 F (72C) for 15 minutes. Ultrapasteurized, or non-perishable milk is heated to 300 F (149C) for 3 seconds.

Irradiation of food employs two common methods - exposure to gamma-radiation produced during the decay of radioactive cobalt-60 source, or exposure to a beam of electrons produces by an electron gun. Electrons passing through living matter collides with some molecules and leaves a trail of altered or broken molecules along with newly formed, chemically active ions and free radicals. (Free radicals are electrically neutral, but very chemically active atoms or molecular fragments.) The ions and free radicals may in turn break even more molecules, or create new molecules harmful to the cell. If the radiation passing through germ is strong enough, it will alter its DNA and make it unable to reproduce, or even will kill the cell.

Note that this is how a radiation therapy works for cancer patients - high level of radiation is carefully directed onto the cancerous cells to kill them or render them unable to reproduce.

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