Since I have been a regular user of a mobile phone for the last two yuears I had been concerned about adverse effects of prolonged use on my health. Thats when I started reading literature about this topic.
I have found that apart from some fatigue on the ear it causes little damage.
Mobile handsets operate on Radio Frequency that emits power levels between 0.2 to 0.6 Watts. The farther you hold the phone from your head the lesser the exposure to this emitted power. Prolonged usage can lead to increase in heat under the skin(a maximum of 1 centimeter) in the area where you hold the phone. Although the blood circulating in the body takes away this generated heat, health effects that have been reported have been related to heating only. Studies so far have rules out Cancer and other serious illnesses due to use of mobile phones.
Thats why it is recommended to keep the phone away while talking; use a hand-free kit if available.
For reading the full report from World Health Organization(WHO) please visit this link -
https://who.int/inf-fs/en/fact193.html