New Delhi, Feb 15 (IANS): At a time when various studies are going on whether radiation from mobile phones is harmful for health, an US expert Saturday said no study or research has proved that non-ionizing radiation, as produced by these devices, causes cancer.

"No study or research about cancer has proved that non-ionizing radiation causes cancer. There is a campaign doing the rounds that the use of mobile phones or the proximity to mobile phone towers can cause cancer.

"Proponents of the theory question arguments in favour of the safety of mobiles. How can you be so sure about it since cancer develops in the body in 20 or 30 years, they ask. Mobile phones have been around for only 20 years," M.V.Pillai of Jefferson University said at an event organized by Indian Medical Association and the Press Club.

Electro-magnetic spectrum has two types of radiation on either end. On the right side is the ionizing radiation represented by X-ray, gamma ray and nuclear reactors, which is dangerous. Non-ionizing radiation on the left side of the spectrum is not harmful.

"But there have been many studies conducted in animals. They have been exposed to wi-fi and microwaves. None of these researches have proved that non-ionizing radiation causes cancer. In other words, non-ionizing radiation is proved to be harmless," he added.

Pillau mentioned that if someone speaks on mobile phone for a long time, it generates heat.

"Though the heat does not damage DNA's structure, it could affect other proteins. Research should go on in this aspect. Whatever the case may be, it is not advisable to speak on mobile phone for hours," he added.

The World Health Organisation is conducting many studies on this. He said a report scheduled to be published in 2016 may bring some clarity on this matter.