Tawkon's (pronounced talk-on) application is already available for Research In Motion's BlackBerry handsets and will be launched for Google's Android-based phones and Nokia's Symbian later this year.

We are the first solution that can be downloaded to a phone, Tawkon co-founder and CEO Gil Friedlander told Reuters. Until now radiation emissions were measured with an external device.

In many countries handset manufacturers must disclose the maximum level of radiation emitted and similar legislation is starting to appear in the United States, Friedlander said.

The application monitors the phone user and if radiation levels reach a certain threshold called the red zone an alert is emitted along with suggestions to minimize exposure.

There are simple things you can do such as changing the phone's position from horizontal to vertical, Friedlander said.

On many phones the antenna is on the bottom and often covered by the user's hand, causing the phone to emit more radiation. Connecting an ear piece or switching on speakerphone will reduce radiation exposure. In addition, Tawkon is connected to GPS and the software will show users where to move to reach a green zone and reduce exposure.

We don't want people to stop using phones but to use them more responsibly, the Canadian-born Friedlander, 44, said.

Tawkon initially targeted its software for the iPhone, but said Apple rejected it in March for sale in its App store.

The media picked up on it... and a week later I got a phone call from Apple saying they wanted to talk with us. They are trying to see how they can get it into their App store, Friedlander said.

Friedlander would not disclose how many users Tawkon has but said every three days the number of downloads doubles.

San Francisco became the first U.S. city to pass a law requiring retailers to post radiation levels on cell phones and Friedlander said he believes Tawkon will benefit from this increased awareness. It will launch its application for phones based on Google's Android software in San Francisco in a month.

It will take a few years until research (on the health effects of cell phone radiation) will be more conclusive, Friedlander said. A lot of regulatory bodies are concerned this will be too late for a whole generation. To take precautionary measures is the right thing to do.