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Here we are again going back and forth on whether or not cell phones cause brain cancer. Even though basic physics mostly rules out the possibility, fears have not subsided. Creating another scare, the World Health Organization recently put cell phone emissions on a list of other possible carcinogens.

But before you go buy a bluetooth headset, what exactly is the context behind this classification?

The List

It is true that the International Agency for Research on Cancer has now included cell phone use as a possible risk. However, let’s focus on the term “possible.”

The IARC develops a list of carcinogens, from proven to possible, in groupings of 1, 2A, and 2B (the ones that concern us). Group 1 is composed of known carcinogens like plutonium. Group 2A is composed of probable carcinogens like coal-tar. These first two categories have a significant difference from the last (2B). They have empirical evidence to support or suggest carcinogenic properties.

If we move on to the group where cell phone use has been placed, possibly carcinogenic, take note that there is no evidence or consensus to confirm a cancer-causation for any substance or activity in this group. Although cell phone use is in this possible group, so is coffee, carpentry, and dry cleaning. If you are willing to inaccurately state something like “Cell phones cause cancer, so keep them away from your head!”, you must also be willing to go into Starbucks and convince the drinkers that they are doomed.

When viewed in this context, there really is nothing to worry about. There is no hard evidence that cell phones cause cancer, not any more than coffee at least. Remember, possible is very different from either known or probable.

But even a list needs validation. The exoneration of cell phone use comes from physics.

The Physics

Taking note of the graphic below, notice where each wavelength lies, what produces them and what biological effects they have.

Graphic courtesy of Jerrold Bushberg. Reproduced with permission from The Essential Physics of Medical Imaging, 3rd edition, by Jerrold Bushberg et al. © Lippincott Williams & Wilkins, 2012.

As we can see from the above graphic, cell phone radiation is non-ionizing, which means that it cannot break the molecular bonds necessary to be carcinogenic. It’s the same reason why you don’t get cancer from standing in front of a radio. The emissions just are not powerful enough to cause any biological harm.

This does not mean that the radiation emitted does nothing however. The radiation from cell phones and other electronic devices may heat molecules in the body (think microwaves) but does not ionize them (that is, set electrons free). Ionizing radiation, which can tear molecules apart and therefore potentially damage DNA—is the greater worry, and is way beyond the power of a cell phone. We’re talking about Hulk-generating radiation here.

Non-ionizing radiation is all around you all of the time. Just turn on your radio and turn it to a static channel. All that noise and interference that you hear is radiation all around you being picked up, some cosmic and some man-made, and hits you probably every second of every day. If such pervasive radiation indeed did cause cancer, we should see many more cancer patients as a result, but we do not.

Consider the separation between non-ionizing (radio, microwave, etc.) and ionizing (gamma, x-ray, etc.), the spectrum of visible light, as a barrier of protection. Anything above it is considered dangerous and anything below it has so far been found to be harmless.


To date, the scientific consensus is that cell phones do not cause brain cancer. It is no more carcinogenic than drinking coffee or building a bench, and physics prevents it from even making it underneath your skin. You’re safe. Keep talking.

For a further explanation of why the connection is implausible, refer to a previous post: “The Cell Phone and Brain Cancer Myth“.