Do mobile phones cause brain tumor? Why mobile phones are prohibited in the elevators?

So you’re running late for work and you’re taking the elevator up to the 14th floor. Next thing you know, someone walks in while talking on their mobile phone. Nothing unusual right? Suddenly, the guy next to you gets all wound up and yells “Don’t you know that you shouldn’t use a phone in an elevator? You are going to fry our brains with the radiation!”

This isn’t just a made up story. I’ve seen signs next to elevators telling people not to use their mobile phone in an elevator. But why? Is it true that mobile phone radiation is amplified in elevators? And could this cause health problems like brain tumors? Let’s find out.

How mobile phones work?

Before we get to elevators, let’s look at how mobile phones work in the first place.

Let’s say you call your uncle to invite him to a family Christmas party. While you are talking, a microphone listens to your voice and a small processing unit converts your voice into a digital signal. This digital signal needs to get to your uncle, but how can this be done without a wire connecting the two phones?

Well the antenna converts the digital signal of your voice into electromagnetic waves that can be transmitted wirelessly. To transmit this information, cell phones use the microwave part of the electromagnetic spectrum.

Microwaves have high energy than radio waves, but less energy than infrared or visible light. The microwaves from your mobile phone aren’t strong enough to get to your uncle directly. Instead they are sent to the closest base station. These base stations ‘listen’ to microwaves sent from your phone and send the signal through land based phone cables to a base station that’s closest to your uncle. This second base station converts the signal back into microwaves, and sends them to your uncle’s phone. Your uncle’s phone’s antenna picks up the microwaves and converts them back into a voice signal that he can listen to. Amazingly, all of this happens while you argue about who’s going to wear the Santa outfit this year.

Is microwave radiation harmful?

So what do we know about microwave radiation, and could it be harmful?

Microwaves are all around us. Have you heard of the Cosmic Microwave Background Radiation? This is faint microwave radiation that is thought to have resulted from Big Bang and is present throughout all of space. The sun also emits microwaves, although most of it is blocked by the Earth’s atmosphere.

So how do microwaves effect your body?

Well the main effect is the ‘thermal effect’ of microwaves. When exposed to enough high power microwave radiation, molecules start to move faster and this generates heat. This is the principle that is used when heating up food in a microwave oven – water molecules in food move faster and the heat produced by this vibration warms up your food.

We know that the microwave radiation from your phone is too weak to cause any significant heat generation.

Do mobile phones cause brain tumor?

But what about non-thermal effects? For example, we know that when using a mobile phone, the head gets more radiation than the rest of the body. So is it possible mobile phones could cause brain tumor?

Well there are two ways we can answer this question: we can do experiments in the lab or do experiments on humans. We know that the first step in the development of cancer is damage to our DNA. Most lab studies have shown that microwaves cannot damage our DNA. So this has been reassuring.

There has been one experiment that exposed rats and mice to astronomical amounts of microwave radiation and there were some health effects but only in male rats. Interestingly, there were no health effects seen in female rats, male mice and female mice.

Overall, scientists are not convinced that this result applies in humans. But the good thing is that it has made scientists more vigilant about the potential health effects of microwaves.

So what about studies in humans?

Well obviously we can’t experiment on humans directly. Instead, scientists have been using other indirect techniques to study the effect of microwaves on our health.

Some researchers gathered people with and without brain tumor, and asked them to remember how much they used their cell phone. This is called a case-control study and as you can imagine, the results from these kind of studies are very difficult to interpret. This is because this kind of study relies on people’s memories from what they’ve done years ago, and I can barely remember what I had for breakfast last Saturday! Still most of these types of studies have not shown a consistent relationship between mobile phone use and brain tumor.

Another technique is to look at the number of people being diagnosed with brain tumor and see if this is increasing. We know that the number of people using mobile phones has increased dramatically over the last two decades, so if mobile phones do cause cancer, we should see an increased number of people being diagnosed with brain tumor.

An Australian study of this type was published in November 2018. It confirmed that there has been a massive increase in the number of people using mobile phones from 1990 onwards. But brain tumor rates have remained stable. Even with a follow up period of 15 years, there hasn’t been any significant increase in brain tumor rates.

So as far as we can tell, microwaves from mobile phones don’t cause brain tumor.

A key safety mechanism that helps to protect us, is that there are strict international limits so that mobile phones only emit very low amounts of microwave radiation. In normal use, mobile phones never really reach this safety limit. They normally only emit 35%.

Impact of elevators on mobile phone’s radiation.

But there are some circumstances when the radiation level from mobile phones could get to the full limit, and that’s where the elevator situation comes into play.

While you are talking on your phone in an elevator, your mobile is still trying to communicate with the base station, but the microwaves are blocked by the metal construction of the elevator, the thick concrete that makes up the elevator shaft and all the concrete and steel rods in the main building. To compensate for this, mobile phones increase the power of microwaves in a desperate attempt to maintain the connection to the base station.

Also, the elevator is essentially a big metal box, so microwaves can reflect off the walls and become trapped.

Both of these factors mean that amount of microwave radiation in an elevator can increase dramatically compared to normal cell phone use.

In computer simulations of this kind of situation, the maximum amount of radiation in an elevator can exceed the safety limit by about 3.8%. This won’t fry your brain, but it’s still more microwave radiation than you need to be exposed to.

So overall, it’s a good idea not to use your mobile phone while you’re in an elevator. I mean you’ll get terrible reception and be exposed more microwaves. Neither of these sound like a good idea.

But one thing that struck me while researching for this article, is why we worry so much about the theoretical effects of mobile phones, when there are so many real risks associated with cell phone use.

Have you seen someone crossing the road while texting? Or maybe you’ve seen someone driving along the freeway while looking down on their mobile phone? It only takes a split second of distraction for there to be a serious accident. So the next time you pull out your phone to send a text or make a phone call, maybe just take a second to make sure that you are not putting yourself or others in danger.