Mobile Phones and Cancer - Physics to the Rescue

Sat, Feb 3, 2018

Every time another study claims to have found a link between an increased cancer risk and mobile phone usage, like the newest NIH study here (TR-596) I cringe in my chair, awaiting the hordes of inept journalists to jump on the bandwagon and proclaim practically the end of civilization due to death by smartphone. Of course if the media is writing about it then the average Joe is inclined to believe it, even though this question can actually be approached with some common sense.

So what is cellphone radiation? Cellphones emit microwaves, which is the designation for electromagnetic radiation with a wavelength between 1 mm and 1 m or a frequency between 300 MHz (3 * 108 Hz) and 300 GHz (3 * 1011 Hz). Which frequency is emitted by your cellphone depends on the network and technology in use. Most phones operate around 900 MHz, 1900 MHz, or 2100 MHz, depending on the frequencies in use in your country. Here is a nice graphic that shows the range of the electromagnetic spectrum by the way. So, how can this harm us? If you are wondering whether the term microwave refers to the same device that you use to heat up your food then you are correct, but hold your horses for a minute, it all depends on the power! And before we come to that, let us examine what ways there are to affect tissue in a way that this could lead to something like cancer.

Destroy the DNA with ionizing radiation

A surefire way to get cancer is to break up the bonds that hold your DNA together. While your body has ways to repair broken DNA, it sometimes makes mistakes while doing so. The more mistakes happen, the higher the chance that the DNA will be distorted in a way that using its (now errorneous) information to produce otherwise useful things for your body, now leads to the formation of a malignant tumor that grows and spreads. So the first and most obvious way to get cancer is to cause as many breaks in the DNA as possible.

Your DNA is held together by ionic bonds which have a certain force of attraction if you will. If something highly energetic comes along, think of something like a bullet, and hits this bond, it can break. However, your bullet needs to have a certain amount of energy so it can actually overcome the ionic bond or nothing will hapen. Think of taking a cannonball and throwing it against a house wall with your hands. You can probably do this all day and nothing much will happen. Load that cannonball into a cannon first and fire it at the house and it will go right through. This is of course because the cannonball has more (kinetic) energy when fired from a cannon since your arms are just too weak to give it sufficient energy.

It really is the same with electromagnetic radiation or photons, which is one and the same. A photon hitting your DNA must have a certain amount of energy or nothing will happen. Throwing more than one low-energy photon at your DNA does not help either in the same way as it does not help if you and your friends throw cannonballs at a wall together. More balls do not make up for one ball with enough energy to penetrate…. let’s use a different analogy next time. :o) Long story short, more particles do not help, they need to have enough energy in the first place!

Can mobile phones destroy your DNA?

So, how much energy do you need to destroy DNA? The range of ionizing radiation starts at around 120 eV which is short for electronvolt and is the unit physicists like to describe the energy of particles with. There is no need to understand the background of electronvolts or how to convert it into different units of energy as you will soon see, it is all about the ratio. So everything above 120 eV will be able to destroy your DNA but the more your are below 120 eV the less likely this can happen.

The higher the frequency of a photon, the higher its energy so lets take the highest frequency we have for mobile phones which, as I wrote above, is 2100 MHz. Let’s make it 3000 MHz just for kicks. At that frequency a photon will have the energy of 12 µeV which is microelectronvolt. Micro is a millionth so a mobile phone microwave photon has 12 millionth of 1 eV of energy. How many eV did we need to destroy our DNA? Around 120. This means that photons emitted from mobile phones only have one ten millionth (0.0000001) the amount of energy that would be needed to ionize our DNA bonds and lead to cancer this way. This will never ever happen! CASE CLOSED

What about the heat?

Another way to get cancer is by heating up your tissue in excess of 42 °C which leads to proteins to denature, a fancy way to describe killing cells if you like. This is also one of the reasons why a really high fever can be life-threatening. So if you kill cells, your body has to replace them. When building new cells, your body can fuck up, so to speak, and put something together the wrong way. If the resulting misbuilt cell starts to multiply like crazy and spreads around, there’s your cancer again. So, since we cannot ionize the DNA with microwave radiation, can we maybe heat up the tissue enough for cells to die so they have to be replaced? After all, your microwave oven can also heat up your food pretty good.

This is where the amount of photons comes in. While more photons hitting your tissue do not raise the chance to destroy DNA if they do not have enough energy to do so, they do warm up your tissue. This amount of photons is what we call power and we usually use watts (W) to describe it. Your microwave oven usually has something in the order of 800 W of power. This means a whole lot of photons hitting your food, which then gets really hot. You really should not stick your head in there which is why microwave ovens have a safety switch so they can not be turned on if the door is still open. (Put down that screwdriver and leave that safety switch alone! It’s there for a reason!) Your mobile phone has a lot less power!

The current SAR (specific absorption rate) limit for exposure to radiation is around 1.6 W/kg or 2.0 W/kg depending on the limits enforced in your country. This basically describes how much power per kg of tissue is deemed safe. The SAR rating of your phone will be even less. Most phones are in the range of 0.2 W/kg to 1.0 W/kg. If the reception is good the phones also throttle down to save battery, their power output in that case is even only a fraction of these values. There is a nice website from the Bundesamt für Strahlenschutz (the German agency for protection from radiation) where you can look up the SAR values of hundreds of phones (available in English). (Please don’t mind them using the German word for mobile phone which is Handy. So if they ask you for your handy model don’t get any funny ideas, just input the model of your cellphone ^^)

As we can see, mobile phones only have tiny amounts of power compared to a microwave oven (Lucky us!). Is this enough to maybe at least get your tissue to 42 °C? There has been research conducted by Van Leeuwen, et al. who developed a head temperature model based on MRI scans to investigate the effect of microwave radiation on the tissue temperature. On top of it all, they also verified their model by experiments they conducted to measure the skin temperature rise, so this is a pretty solid piece of work.

The blood circulating in our veins is the main source of cooling and heat transport in our body, else we would overheat. Also, simple physics tells us that the more difference in temperature there is between two areas or volumes, the more the heat transport is increased. This also means that as tissue warms up, the temperature difference to the blood temperature becomes larger and thus the heat transfer to the blood gets stronger resulting in even better cooling. If you have a constant heat source, the temperature rises at first but then, as the cooling becomes more efficient, levels out and stays at a constant value without increasing further unless you apply more power. Van Leeuwen found that the maximum rise in brain temperature after hours of constant mobile phone usage was 0.12 °C. A bloody tenth of degree! The average body temperature of a human can easily vary by as much as 1 °C throughout the day. How is this supposed to create cancer problems for you? You should be more affraid of getting cancer from catching a cold with the resulting fever.

So have fun, go about your business, use your phone as much as you want, and stop worrying. Also stop fucking telling people that they get cancer. Oh, before I close this, how did the newest study I mentioned at the very top determine that there is an increased risk for cancer? Well first of all they blasted mice with 10 W/kg of radiation. Your body cooling system is efficient but it will crap out at some point. You can not simulate a long exposure by increasing the dosage if a lower dosage is completely safe in the long run. We have a built-in “air conditioning” and of course you can make it fail if you make it hot enough. They could’ve put the mice into a microwave oven and then complained about health side-effects, same deal.

Oh and they don’t seem to be so sure of themselves either:

The combined incidences of fibrosarcoma, sarcoma, or malignant fibrous histiocytoma of the skin were increased in 5 and 10 W/kg males, although not significantly or in an exposure concentration-related manner.

Great, not only did we up the dosage to an unrealistic level, it also hardly shows any difference…