Mobile phones have changed the way we communicated with each other since the early 90’s. From pay phones and land lines, to pagers and then from regular mobile phones to smartphones, communication has gone from just speaking to instant communication and sharing information. However, for a few years now, radio signal emissions from mobile phones and mobile towers are a big concern.
Science and scientists are continuously researching on radio waves emitting from your mobile phone. Their research has still not given 100% proof that a mobile phone or a mobile tower causes cancer and other dangerous health risks to living beings.
The recent outburst of new-age low budget smartphones causing dangerous radiations, which pose a high-risk to human health, is being highlighted. Xiaomi has been in the recent news with their new smartphones, the Mi 3 and Redmi 1S having radio emissions beyond the proposed safe value. But how much is a safe value? How much does your present smartphone radiate dangerous emissions? Which is the best smartphone to use safely?
SAR, Specific Absorption Rate, is a value or measure of the rate at which radio waves is absorbed by the human body when exposed to a radio frequency electromagnetic field. It is defined as the power absorbed per mass of tissue and has units of watts per kilogram (W/kg).
SAR is usually averaged either over the whole body, or over a small sample volume (typically 1 g or 10 g of tissue). SAR measures exposure to fields between 100 kHz and 10 GHz (generally known as radio waves). It is commonly used to measure power absorbed from mobile phones and during MRI scans. The value will depend heavily on the geometry of the part of the body that is exposed to the RF energy, and on the exact location and geometry of the RF source. Thus tests must be made with each specific source, such as a mobile phone model, and at the intended position of use.
When measuring the SAR due to a mobile phone the phone is placed at the head in a talk position. The SAR value is then measured at the location that has the highest absorption rate in the entire head, which in the case of a mobile phone is often as close to the phone's antenna as possible. Various governments have defined maximum SAR levels for RF energy emitted by mobile devices.
In the US, the SAR value is 1.6 (1.6 watts per Kg), in EU it is 2.0, while in India, it is the same as US limits. However, India has also considered government-run tests and will not solely rely on manufacturer SAR measurements.
The FCC states that all cell phones should meet an exposure standard. For users who are concerned, they should use hands-free mode or a hands-free accessory in order to reduce the risk of health hazards.
Exposure to continuous radiations from mobile phones can have two types of effects on the human tissue—thermal and non-thermal.
According to Wikipedia, one well-understood effect of microwave radiation is dielectric heating, in which any dielectric material (such as living tissue) is heated by rotations of polar molecules induced by the electromagnetic field. In the case of a person using a cell phone, most of the heating effect will occur at the surface of the head, causing its temperature to increase by a fraction of a degree. In this case, the level of the temperature increase is an order of magnitude less than that obtained during the exposure of the head to direct sunlight. The brain's blood circulation is capable of disposing of excess heat by increasing local blood flow. However, the cornea of the eye does not have this temperature regulation mechanism and exposure of 2–3 hours duration has been reported to produce cataracts in rabbits' eyes at SAR values from 100-140W/kg, which produced lenticular temperatures of 41°C. There were no cataracts detected in the eyes of monkeys exposed under similar conditions. Premature cataracts have not been linked with a cell-phone use, possibly because of the lower power output of mobile phones.
The risk from non-thermal effects is still in debate. The research on non-thermal risk states that the health hazards include a possibility of cancer, blood-brain barrier effects, cognitive effect, electromagnetic hypersensitivity, genotoxic effects, sleep and EEG effects, brain glucose consumption, behavioural effects, sperm count and sperm quality, and a few more.
SAR value and the effect of the radio waves on human body health are still a debate. What is the SAR value of your smartphone? If you are concerned, you can check the SAR value of your phone by logging on to the SAR Shield website and check the details for your smartphone.
However, before you do that, here is a short list of the SAR values for the most popular smartphones in India.
With inputs from Wikipedia. SAR values as per SAR Shield website.
Image credit: HealthTap.com
