By Nicole Chiu - Contributing Health Journalist

Cell phone usage and its relations to developing cancers is an issue, which has been heavily debated in the scientific research world. Dr. Ronald Herberman, director of the University of Pittsburgh Cancer Institute and the Cancer Centers at the University of Pittsburgh Medical Center has issued a warning about long-term cell phone usage.

Herberman's warning is based on his recent awareness of the growing body of literature linking long-term cell phone usage to "possible adverse health effects including cancer."

"Although the evidence is still controversial, I am convinced that there are sufficient data to warrant issuing an advisory to share some precautionary advice on cell phone use," wrote Herberman in a memo he issued out to the 3000 faculty and staff members under his supervision.

Similar warnings have been issued in several European countries, and in Toronto, Canada, the public health agency has declared that children should avoid using cell phones. This is due to children's organs being especially sensitive to any possible effects as they remain in the development stages of growth.

Herberman's review of the literature surrounding the issue of cell phone usage in adults includes preliminary data, which has suggested that long-term users of cell phones are at higher risks of developing brain tumors. The tumors in such studies were also found to be developing at the sides of the heads where cell phones were usually placed.

Herberman's warning is significant as he is the first director of a US cancer center to speak out about this issue of long-term cell phone usage.

Though his warning does not suggest that people cease cell phone usage completely, he makes recommendations for reductions in usage.

Some recommendations for avoiding risks of developing cancer include: using headphones instead of placing the cell phone directly to the ear, send text messages instead of calling for short messages, keeping conversations lengths to a bare minimum, and using speaker phone when possible – especially if conversations need to take up more time.

Herberman's memo has referenced an ongoing study of cell phone users in 13 European countries.

"It makes sense to limit risks," said Dr. Dan Wartenberg of the University of Medicine and Dentistry of New Jersey, who, along with Herberman and 20 other international experts, has signed a letter calling for precautions on cell phone use.

The letter also includes a request for cell phone manufacturers to release products that have the "lowest possible risk."