Cell phone microwave

Posted on 26th Sep 2017

Some time ago a colleague asked me about the dangers of smartphone radiation. He was of course pointing to the fact that cell phone radiation could possibly cause cancer. As we talked I explained that the absorption of radiation in the body causes the body to heat up. This in turn could lead to deviation in cell behaviour which could result in cancer.

Since a lot of research is done but none provide conclusive results one could state that the dangers are very low. So low in fact that I would call it negligible, especially compared to the amount of lives mobile communication saves!

As soon as we ended up at this conclusion we derailed and started wondering how many cell phones would cause a deadly body temperature.

So…let’s do some rough calculations.

A cell phone emits around 125 – 500 mW of power. Let’s assume a worst case scenario and say that out of 500 mW emitted roughly 50% is absorbed into the body (0,25 W or J/s). This causes the body temperature to rise. However, the human bodies thermoregulation is able handle temperature increases.

Let’s assume that it can do this at a rate of around 300 W (it varies widely depending on activity and environment; 1,2). So in order for the body to heat up faster than it can cool down you would need over (300 / 0,25) 1200 smartphones.

Assuming the human body has roughly the same heat capacity as water and the body size of the reference man defined by the ICRP (3, 70 kg) we can calculate the amount of energy needed to warm the body. So, in order for the body to heat up to a deadly 41,5 oC we would need 1,3*106 J.

Knowing this we can say it would take ((1,3  * 106 / 0,25) + 1200) 1201 cell phones roughly 10 years to heat up the body to dangerous levels. Which, let’s be frank, takes way to long! About 5200 cell phones could have the same result in just under a day!

We did not take into account the fact that smartphone emit heat themselves. This could compensate for the fact that a body loses relatively more energy to its surroundings the hotter it gets.

Minor disclaimer (if needed): This calculation is ways away from any precise scientific approach it does however point us towards an order of magnitude.