Scientists still are not sure whether cell phone use clearly is linked to brain cancer.

Cell phones’ electromagnetic radiation frequency ranges from about 850 to 1900 megahertz. This type of radiation is classified as non-ionizing radiofrequency energy, which typically is safe. It causes a heating effect, but usually not enough to cause severe long-term damage.

Non-ionizing radiation does, however, have the possibility of causing tissue damage because of the ability to heat living tissue.

According the the American Cancer Society, the U.S. cell phone industry has conducted studies that showed mixed results on the topic. In a study published in 1999, investigators at the Orebro Medical Centre in Sweden compared the past mobile phone use of 209 Swedish brain tumor patients and 425 healthy people. The conclusion showed there was no clear link to the patients’ cancer.

“From my knowledge, cell phones don’t give any radiation that causes brain cancer,” said Dr. Bharati Bhate of the Illinois Regional Cancer Center.

According to electronics.howstuffworks.com, cell phones emit radiation through a transmitter that takes the sound of one’s voice onto a continuous sine wave, which is a wave that radiates from the antenna. Sine waves are measured in frequency, the number of times per second a wave oscillates up and down. Once the encoded sound is placed on the sine wave, the transmitter sends it to the antenna. Finally, the signal is sent out.

Most cell phone users hold the phone directly against their head, which is why scientists began to worry about long-term effects of heating brain tissue.

There are a few illnesses and ailments that have potential links to cell phone radiation, including brain tumors, Alzheimer’s, Parkinson’s and fatigue. These have not yet been proven.

Margot Brown, senior director for Motorola, said the company still is confronted with frequent lawsuits, but they get thrown out of court because of a lack of scientific evidence.

According to the Web site, there are ways for cell phone users to better protect themselves, including extending the antenna during use and limiting calls inside buildings. It’s also recommended to use a cell phone in open spaces as often as possible.