Last week the World Health Organization (WHO) listed cell phones as “possibly carcinogenic to humans”. You may be more disposed to listen to an important international health organization than your favorite Local Buzz science blogger, but I strongly suspect they are wrong. There have been multiple studies on this topic over the years and most studies have not found a link. The few studies that have purported to find a link have been criticized for their methodology. The National Institutes of Health (NIH) is on my side.

Now I understand that if the WHO lists a popular device like the cell phone as a possible carcinogen, this is going to prompt a large number of news stories. But certainly there is no reason that the stories all have to be so insubstantial and simply regurgitate the press release. If you read my introductory blog you will recall that this is just the sort of science reporting that drives me crazy. There is no analysis and no attempt to give the reader any context for understanding.  For me many questions come to mind when I read a story like this. To keep the blog at a reasonable length, I’ll only address one:
·         Is this plausible?
A friend of mine was recently considering purchasing cell phones for her two sons. She had heard some reports about the possibilities of getting cancer from cell phones and asked for my advice.  This gave me a chance to address the plausibility question.
I will share the answer with you in a moment, but first we need to talk about electromagnetic radiation (EMR). Discussion of EMR can be one of the most unapproachable parts physics class. Let me shoot for “simple” version here. The universe is made up of both matter and energy. Energy and matter are related by Einstein’s famous equation:
E= mc2
The E in the equation stands for energy which exists as electromagnetic waves, the “m” stands for mass and “c” is the speed of light. The difficult concept (at least for me) is conceiving of energy moving as a wave thorough space. EMR with long wavelengths have low energy (like radio waves). EMR with short wavelengths have high energy (like gamma rays). The key thing to know is that all electromagnetic waves are all the same type of energy with a spectrum of wavelengths and strengths. In physics class you probably were shown a chart like the one at the top of the blog to help you to conceptualize this.
OK back to my friend who was concerned about her sons. Here is the answer I gave her:
Cell phones operate on radio waves, just like any other radio. Radio waves are part of the electromagnetic spectrum. To make things easier to talk about we like to give names to different energy segments of the spectrum. Starting from low energy to high energy we call these segments, radio waves, microwaves, infrared radiation, light, ultraviolet radiation, x-rays, and gamma rays. They are all electromagnetic waves which vary in their strength. 
In order for you to get cancer from electromagnetic radiation the waves need to be strong enough to damage strands of DNA in your cells. So let’s consider what we know about the probability of getting cancer from electromagnetic radiation starting from the high energy side of the spectrum. Gamma rays (these generally come from nuclear fission) are strong enough to give you cancer with only a short dose.  X-rays can give you cancer with repeated exposure.  UV rays can give you cancer after decades of exposure. Here is a really critical point on UV rays though. They are not energetic enough to penetrate deeply into your body, so they can only give you skin cancer, not an internal cancer like you can get from gamma rays or x-rays.
Now consider the part of the electromagnetic spectrum which is lower energy than UV rays. We walk around in the light all day long every day. We feel the warming of infrared radiation (heat basically) all day long (especially last week).  At the low energy end of the spectrum, we are bathed in radio waves (same as cell phones) all day long as we listen to WCHL.
The concern addressed by the WHO for cell phone use is brain cancer, an internal tumor. As discussed above, the radiation needs to be at least a strong as an x-ray to cause an internal cancer. A radio wave is 100,000,000 times less energetic than an x-ray. Please be reassured.
I must have been at least modestly convincing as the boys did get their cell phones.
Even if the WHO is correct about the risk of cancer and the NIH and Common Science are both wrong, car crashes due to driving while talking on your cell phone are a far greater danger to you than the radio waves from your cell phone.   Even the WHO lists cell phones in the same category of carcinogenicity as coffee and pickles.  So hop in the car, put your phone down, and turn on AM 1360, WCHL “Your News, Talk, and Tarheel Station.
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