Both you and I are only two of the five billion mobile phone users out there. Our phones have become a daily necessity for us. Have you ever wondered how much radiation you absorb when making a phone call, downloading a file or simply when keeping a phone in your pocket? How safe is it? And how did SAR come about?
What is SAR?
SAR stands for Specific Absorption Rate and is defined as the power absorbed per mass of tissue and has units of watts per kilogram (W/kg). What does it really mean?
Because we live in an electromagnetic (EM) universe (think light, colour, infrared – all of which are part of the electromagnetic spectrum) we interact with a variety of EM sources every day.
Some of them are natural to the body and can be beneficial to us. Others, although naturally occurring, can have damaging effects (think sunburn). In addition to the natural sources of EM waves, humanity was clever enough to come up with EM sources of our own, to initially win our wars and to eventually take the human race to the next level of our evolution (think mobile phones, Wifi, microwaves).
What happens when you make a call
When you place a call to your loved one, your phone (through its sophisticated antenna) cleverly sends your order (the information in the form of a signal) to a much stronger tower nearby. This tower then passes on this information, via the huge network of mobile masts, all the way to the loved one of your choosing.
Your body is a sponge
This invisible transmitted signal is made of a type of energy, which we call the radiofrequency energy. It is measured in mili-Watts (mW).
Your body, on the other hand, is formed of biological tissues, whose mass we measure in kilograms (kg).
In the process of connecting and transmitting your call, the phone signal spreads out in many directions. The main bulk of this signal continues to the mobile tower but some of it gets absorbed into whatever it is in its close proximity. You, holding your phone by your head, become the ‘sponge’ or ‘absorption pad’ (in kg) of this energy.
How is SAR calculated?
When we measure SAR, the Specific Absorption Rate, we, in fact, calculate how much your body (biological tissues) absorbs a chunk of this energy (in Watts per kilogram)
In more technical terms, it is the measurement of radiofrequency (RF) energy absorbed within grams of biological tissues when exposed to a radiofrequency electromagnetic field.
Going back to the very beginning, now it might be a little bit clearer what it means when we say that SAR value is the power absorbed per mass of tissue and has units of watts per kilogram (W/kg).
It is usually averaged either over the whole body or over a sample volume (typically 1 g or 10 g of tissue). The SAR value you see published is then the maximum level measured in the body part (e.g. head) studied over the stated volume or mass.
What is the SAR value in an adult?
The current SAR value, which the maximum permitted exposure value, is 2W/kg in Europe and 1.6W/kg in the USA. This is enforced on the phone manufacturers by different regulatory bodies in Europe and the USA. The measurement is usually done with a phantom head and body at a small distance (around 5mm).
Where did the current SAR standards come from?
First safety standards were set up over 20 years ago around 1997 when a typical mobile phone user was the military, medical or business. At that time it was believed that the only thing to be avoided was the heating effect.
In one of the original tests in 1989, the military used the head of a 220 lb (around 100kg) male at the top 98% of their recruits. The standards they set were to avoid heating of their subject’s brain after a 6min phone call.
Are current SAR standards sufficient?
Definitely not. Current standards might be a tool in judging whether the phone is ‘safe’ by the regulators’ standards, but they don’t accurately assess the full scope of how our health is impacted.
Recently, Prof Gandhi of the University of Utah reported [link to our blog post] that the SARs in W/kg that when held at zero distance from the body, the absorption rate was up to three times higher than the approved European limits and up to 11 times over the US limit.
Here are more reasons why current standards are not enough:
- SAR actually refers to thermal effects but the vast majority of the recorded biological effects from chronic lifetime exposure are non-thermal.
- A number of effects reported at much lower SAR levels than the current safety standard in over .
- Not enough information provided about the amount of RF exposure under typical usage and real-life conditions. The tested exposures under laboratory conditions are only short-term, usually up to a few minutes long.
- No reflection of the variety of head and body sizes. Most of the population have much smaller heads and bodies than the 100kg male military recruit.
- The levels of radiation based on the current usage are much higher today than in the past.
- Current lab testing doesn’t include variations for energy absorption hotspots.
- Different labs might conduct measurements at different distances from the body.
- There is no consideration of the nature of the mobile phone signal. Because it is pulsed in nature, the average power can stay low but the individual signal bursts might be very high.
- The developing brain of a child absorbs much more than the brain of an adult. SAR value in Children vs Adults.
How to reduce your phone SAR?
Research shows that the effects or radio frequencies have been reported at SAR as low as 0.2W/kg after two-hour exposure. This means that you won’t be completely protected from the effects of radio frequencies, even if your phone SAR claims to sit way below the approved limit.
Having said that, there are a few helpful tips we can share with you for better safety:
- Reduce the amount of time you spend carrying your phone in your pockets or holding it in your hands.
- Stop holding your phone next to your ear when calling.
- Opt-in for a hands-free option or use headphones when making a call.
- Choose a mobile phone with a lower SAR rating. This will not necessarily be the key to safety but will still help.
- Keep your phone away from your body when on wifi, hotspotting or downloading data. During those times SAR levels increase significantly.
- Ask yourself – do I really need to spend four hours (on average) a day on my phone? Is it really necessary? If not, simply put your phone aside instead of constantly checking it.
- Switch your phone off or use airplane mode where possible. Not only will it make you safer, I bet you that you will also become less distractive, more productive and more focused on the task at hand.
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References (link where necessary):
- Mobile Phone Users Statistics: https://www.statista.com/statistics/330695/number-of-smartphone-users-worldwide/
- Wikipedia: Specific Absorption rate [https://en.wikipedia.org/wiki/Specific_absorption_rate]
- Dr Devra Davis University of Melbern lecture https://www.youtube.com/watch?v=BwyDCHf5iCY
- Davis, Devra. Disconnect: The Truth About Cell Phone Radiation, What the Industry Is Doing to Hide It, and How t . West 26th Street Press. Kindle Edition.
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Author bio: Veronika Appleford Divincova
Research assistant, educator and content creator at Qi-Technologies.
In life, I believe that with more knowledge and understanding we can make better decisions.