I’m so disappointed with my former employer. Health Canada has issued a recommendation that parents limit their childrens’ cell phone usage due to concerns about radiation exposure. This is a result of the IARC listing radiofrequency electromagnetic fields as one of 267 possible carcinogens — a list (see Group 2B) that also includes coffee, engine exhaust, nickel and pickled vegetables. See Technology Review.
I appreciate that we’re only talking about possibilities and concerns, but this is only going to be grist for those who are freaking out about microwave radiation, whether it’s from cell towers, cell phones, or Wi-Fi networks.
My concern is that while the epidemiology may be uncertain, the physics isn’t. As physicist John Cramer points out in his latest Analog column, it’s physically impossible for microwave radiation to cause cancer. It simply doesn’t have the energy to break a DNA molecule, which is what is required for radiation to create a cancer-causing mutation.
[I]t requires a considerable energy, around 10-20 electron-volts, to break a DNA bond. […] The most energetic photons of cell phone microwaves are those of the 4G networks now replacing the older cell network infrastructure, and the 4G system operates in the frequency range 2.496 to 2.690 GHz (1 GHz = 1 billion cycles per second). The corresponding energy content of 4G microwave photons is 0.00000103 to 0.00000111 electron volts. This means that the mismatch between the energy carried by a cell phone microwave photon and the energy required to damage a DNA molecule is a factor of about one million.
For radiation to cause cancer, it needs to be ionizing radiation — strong enough to pop an electron out of an atom or molecule. That’s limited to the short-wavelength, high-frequency end of the spectrum, i.e. some ultraviolet, X-rays, and gamma rays. They’re why we wear sunscreen at the beach and lead aprons when getting X-rays.
But microwaves? They’re less energetic than visible light. A 60-watt light bulb puts out far more energy than any household microwave source. If you’re worried about microwaves, you have to get rid of all your light bulbs, because, holy fuck, they’re going to kill you!
That’s not to say that microwaves don’t interact with the brain, as Cramer goes on to point out:
After penetrating the skull with reduced intensity, their energy content will generate tiny atomic and molecular vibrations that will show up as heat, slightly elevating the temperature of the head in the region near the cell phone. The body has a strong interest in maintaining the brain in a narrow temperature range, so such external heating will stimulate additional cooling blood flow in the heated region. Recent MRI studies reporting an increase in brain activity related to cell phone use may reflect this phenomenon. But it has nothing to do with cancer.
Microwave heating is, of course, how microwave ovens work. I think that microwave radiation would cook you — literally — long before it gave you cancer. It may not be possible to rule out all adverse effects from heavy cell phone use (indeed, it may never be possible to do so), and I can think of plenty of non-medical reasons to limit kids’ cell phone use; it’s just that it’s hard to see how cancer could be one of them.