Another study that investigated the potential link between mobile phone use and brain cancer adds to the growing body of evidence against any such association, even among long-time users of mobile phones.

“Overall, the majority of the published studies have found no indication of increased risk of brain tumors, and our results are in agreement with these results,” study author Dr. Stefan Lonn of the Karolinska Institute in Stockholm told Reuters Health.

While most previous investigations into the cell phone-brain cancer association have yielded negative results, a few researchers have reported that exposure to radiofrequency radiation puts cell-phone users at increased risk of brain cancer.

However, none of these studies were conducted long enough to properly address the issue.

Lonn and colleagues therefore studied 644 individuals, between 20 and 69 years old, with either glioma or meningioma - the two most common forms of brain tumor. For comparison, their study also included 674 men and women who were of similar age and gender and lived in the same residential areas as the study participants.

Overall, men and women who reported regularly using their mobile phone - at least once a week during the previous six months - for any amount of time were not found to have a significantly greater risk of developing a brain tumor than those who did not report regular mobile phone use. This remained true even among those who said they had used a mobile phone for 10 years or longer, the report indicates.

“We observed no increased risk of glioma or meningioma related to mobile phone use, regardless of tumor histology, type of phone, and duration of use,” the authors write in the American Journal of Epidemiology.

The researchers also looked at the location of the study participants’ tumors, based on the notion that the highest risk of brain tumor would be on the side of the head that receives the most exposure to radiofrequency - i.e. the side where the phone is usually held.

Approximately half of the study participants with gliomas or meningiomas said they held their mobile phones on the right side of their heads, as did just over half of the comparison group. Yet, there was no association between the side of the head where the phone was held most frequently and the location of the tumor, the report indicates.

In fact, the data suggest that the brain tumor risk was slightly lower for the side opposite where the phone was usually held - a finding that suggests forgetfulness, or “recall bias” on the part of the study participants, the researchers speculate.

“It is not biologically plausible that radiofrequency exposure from mobile phone use would increase the brain tumor risk on the side of the head where the phone is usually held and protect against brain tumors on the opposite side of the head,” they note.

“We conclude that our data do not support the hypothesis that mobile phone use is related to an increased risk of brain tumors, Lonn said.

Still, since studies show that a person can develop cancer 10 or even 20 years after exposure to a cancer-causing substance, the association cannot be entirely ruled out and more research is needed, the report indicates.

“Mobile phones have not been used long enough to adequately evaluate their possible carcinogenic effect because of the…long induction and latency period of most solid tumors,” Lonn said.

SOURCE: American Journal of Epidemiology, March 15, 2005.