vitamin c. Take charge of your cell phone

The past decade has witnessed the evolution of the cell phone. A technology that started with a handset weighing around 2 kg has now transformed into phones weighing less than 200 gm, loaded with features that mankind could have never imagined. Most of us are inseparable from our phones today and it is therefore important to be aware of effects that are related to their functionality. The radiation emitted by a cell phone and its batteries are the two critical elements that have a direct bearing on the health of users and the cell phone’s performance respectively.

A regular cell phone (GSM/CDMA) transmits radio waves at 900/1800/1900 megahertz (MHZ). Bluetooth and wireless LAN transfer radio waves at 2400 MHZ of frequency. When a person is exposed to these radio waves, most of the energy either travels around the body (called diffraction), is reflected by the body and some of it is absorbed by tissues at the surface if the body.

Radio waves from the mobile give rise to electromagnetic fields around them. These fields cause water molecules within the human body to move, thereby generating heat, leading to a rise in temperature in the tissues of body parts that are close to the mobile phone. If the frequency of the radio waves is high, the heating is significant and can prove to be potentially detrimental for users. However, new-age mobile phones use low power and heating of tissues due to radio wave absorption is negligible.

It is essential for users to educate themselves about a measurement standard that quantifies the amount of radio frequency energy absorbed in the body. The Specific Absorption Rate (SAR) helps users identify radio frequency absorption rates of the body and is expressed in watts per kilogram (W/kg). SAR values help mobile phone users across the world to be aware of wave absorption standards that are identified to protect consumers.

While the Indian government is yet to come up with a SAR regulation, most mobile phone manufacturers that operate in India follow either the European or American standards.

As per European standards, SAR values should be less than 1.6W/Kg

As per American standards SAR values should be less than 2 W/Kg

The SAR specifications of cell phones are available either in the user manuals of cell phones or manufacturers’ websites.

SAR is measured in laboratories using advanced robot-controlled antennas through simulated human tissue solutions as shown in the picture below.

Given that the SAR measurement information is critical for users, many countries around the world are devising new norms that make the disclosure of SAR levels on handsets, mandatory.

Battery life and safety Another important element in cell phones is the battery. We often read about incidents of cell phone battery explosions and subsequent user injuries. It is important for users to understand basic functionality of batteries, their types and the precautions to be followed.

A battery is the heart of the cell phone as it stores power and supplies it to the system as and when required. The batteries that are charged using chargers convert our main power supply to lower level direct current voltage. Lithium polymer (Li-Poly) batteries is the newest and most advanced technology for cell phone batteries. Ultra-lightweight, they do not suffer from ‘memory effect’ and will deliver up to 40 per cent more battery capacity than a nickel metal hybrid (NiMH) of the same size.

“Memory effect” happens when rechargeable batteries are not fully discharged between charge cycles; as a result the battery “remembers” the shortened cycle and is thus reduced in capacity.

Not needing a cell casing makes Li-Poly cell phone batteries thinner and lighter batteries. However, they are still quite rare.

Lithium ion (Li-Ion) batteries are the current and most popular technology for cell phone batteries. Their only real drawback is that they are expensive. As such, they tend to be supplied with only top-of-the-line phones. Lithium ion batteries are slightly lighter than NiMH batteries, but they also have a longer lifetime.

They can be damaged by extensive overcharging (continuously on a cell phone charger for more than 24 hours).

Nickel cadmium (NiCd) batteries are old technology. This is the rechargeable battery that most people are familiar with. NiCd batteries suffer from memory effect, and they must be completely discharged before recharging or else damage can occur. The chemicals used in NiCd batteries are not environment-friendly, and the disposal of cadmium-rich waste is an increasing problem.

Care instructions Users are recommended to replace only original manufacturer-supplied batteries in the event of battery replacement to prevent any hazard. As moisture/water exposure to batteries is not good it advised to handle cell phones with dry hands and keep away from rain and water exposure. Now some manufacturers have introduced waterproof cell phones which could lessen the burden for the user to take care of this issue.

Suresh Kumar is Senior Vice-President – Consumer Product Services, TÜV SÜD South Asia

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