Maybe cellphones don't cause cancer

Submitted by acohill on Fri, 10/15/2010 - 10:44

Scientific American has a short article on the supposed dangers of cellphones. This is something I have always been worried about, but there has never been any convincing data for or against the supposed dangers. Many of the studies I have read about hedge a lot. I'm still not sure about what to believe, but this article provides some of the physics behind electromagnetic radiation, and it is seems to provide some hard science-based justification for worrying a bit less. In any case, I'll continue to use a wired headset and not keep my cellphone strapped to my waist when I'm in the office. Simple precautions can't hurt.

Hi Andrew, There is a big

Hi Andrew,

There is a big difference between "not causing cancer" and "not causing damage". The Scientific American article is correct that the frequency of mobile devices is not high enough to cause ionization (i.e. knocking electrons out of atoms, which is one mechanism for skin cancer via UV rays), but the article also conveniently left out the fact that mobile devices operate at exactly the same frequency as your microwave oven.

Microwaves have been known to cause cataracts in antenna engineers for decades. See for example,

Computation of the Electromagnetic Fields and Induced Temperatures Within a Model of the Microwave-Irradiated Human Eye
Allen Taflove, Morris E. Brodwin
IEEE Trans. on Microwave Theory Tech., 23, (1975) 888.

When I was concerned about cell phone safety back in grad school (PhD, UIUC, Center for Computational Electromagnetics, 1996-2002), I would put scary looking heat maps of high resolution images of energy absorption from a cell phone into the human head and I'd always get asked if cell phones were safe. At the time, I said I thought they were safe because cell phones were operating at roughly 900 MHz. Most safety studies at the time were based on even lower frequencies.

The degree to which electromagnetic waves interact with material depends on the frequency/wavelength. To get a back-of-the-envelope estimate, just take 30 and divide by the frequency in gigahertz to get wavelength in centimeters. So back when I was in grad school, the wavelength of cell phone radiation was roughly

Wavelength(cm) = 30/frequency(GHz) ~ 30 cm.

More than 2 feet. This means that EM radiation would (roughly speaking) interact most strongly with material on the order of 2 feet. Brains are smaller than that. Hence, my feeling that there was no need for concern.

Today, mobile devices operate at a frequency of roughly 2.5 GHz. Back in 1998, if you told me cell phones would one day operate in the microwave band, I'd tell you you were nuts. C'est la vie.

So today, mobile device radiation has a wavelength of roughly

Wavelength(cm) = 30/frequency(GHz) ~ 12 cm

Just under 5 inches. And to get technical, you'd have to consider the electromagnetic properties of human tissue which would reduce that by roughly a factor of 2.

Can you think of any important human organs that are sized 2-5 inches?

The strength of the signal is not so important either. Recall the Tacoma Bridge? Resonance is a powerful thing and it applies to EM radiation just as it does to bridges. Maybe more so.

If you're interested, you can see some more of my thoughts here:

http://phorgyphynance.wordpress.com/category/broadband/

I agree that we need

I agree that we need continued caution. I use a wired headset (not a wireless Bluetooth device) to keep the phone away from my head (and my brain). When I'm in the office, I take the phone off and put it on the desk several feet from me (there is some troubling data that suggests a higher incidence of tumors in the waist area--where most men keep their phones). And most of the phones in my home are corded--people forget that in-home wireless phones actually operate at higher frequencies than most cellphones.

We are all part of a vast experiment with potentially tragic outcomes.

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