New Delhi, May 29 (IANS): When Gaurav asked for a mobile phone, with all his classmates showing off their smartphones, his mother was unwilling to spend too much on something she believed was only good for making calls. She bought him a smartphone from a lesser known brand, for just upwards of Rs.4,000. But, did she consider how safe it was?

One key aspect of mobile phone safety that most people are unaware of is its SAR or Specific Absorption Rate value. It is a measure of the amount of energy absorbed by the body when exposed to radio frequency (RF) electromagnetic waves such as those emitted by mobile phones.

SAR is expressed in units of watts per kilogram (W/kg). The lower the SAR value the safer the phone is.

Each mobile phone emits radio waves while connecting to the mobile towers, which itself also emits these waves. A part of the energy of these waves is absorbed by the body tissue, and this amount is depicted by the SAR value.

While Gaurav and his mother were elated with his new smartphone, which functioned better than even a branded one costing upwards of Rs.10,000, a chance remark by a friend on the SAR value got them thinking. A close check of the phone showed it had no information on the radio waves being emitted by the mobile set.

Though the effects of radio frequency exposure on human health are still inconclusive, a higher SAR value can mean a potential health hazard. Since mobile phones have become widespread only in the past decade, their effects on human health in the long term are yet to be determined. Even the disappearance of the sparrows is widely believed to have been caused by radio waves emitted by mobile phone towers.

The World Health Organisation urged limits on mobile use last year, calling them a Class B carcinogen, or a cancer causing agent.

Currently, the SAR value limit in India is set at 1.60 W/kg in 1g tissue mass.

"I had to choose between a low end device from a well-known brand and a premium budget device from a lesser known local phone brand," said Delhi University student Vipin. "I chose to go with the better known brand as the SAR value of the local phone appeared to be fairly high."

International mobile phone brands give the SAR value on their phone information menu as well as the official website.

A phone stating a higher SAR value need not mean that it is always more unsafe to use as the phone operates on highest value only when connecting a call. Otherwise it operates on low SAR values.

India is planning to become strict in regulating the amount of radio waves that mobile handsets emit from Sep 1, 2013, and will make it mandatory for phone companies to display the SAR value.

Indian Cellular Association president Pankaj Mohindroo told IANS that from Sep 1 it will become mandatory for all handsets to display the SAR value and only phones adhering to the lower emission rates will be allowed.

"The phone brands that do not adhere to the norm will be rejected," Mohindroo said.

Telecom consultant Mahesh Uppal said the decision to display the SAR level is a "good idea". "It is unfair for consumers to have to choose between affordability and health and any effort to protect consumers is very important," Uppal, of Com First (India) Pvt Ltd. told IANS.