Washington, Oct 21 (IANS) Long-term exposure to cellphone may heighten risk of brain tumours, warned a neurosurgeon.Ron Pawl, a neurosurgeon at Lake Forest Hospital, Illinois has called for collaborative research initiatives to determine whether the link between cell phones and brain cancer is real.

Scientists have long been concerned over the possibility that electro-magnetic fields (ELF) exposure may increase the risk of brain cancers. Until recently, however, research has shown no clear link between cell phone use and brain tumours.

Earlier this year, a Swedish research group published an epidemiologic study suggesting an increased risk of brain cancers (gliomas) as well as acoustic nerve tumours (neuromas) in people using cell phones for 10 years or longer.

Tumours were more likely to develop on the same side as the cell phone was used. Other studies by the same group suggested that the use of wireless handsets in cordless home phones posed the same risk, according to an Elsevier press release.

After reviewing the evidence, one author even suggested that long-term cell phone use is “more dangerous to health than smoking cigarettes”. Other recent commentators have raised similar concerns.

The findings are alarming in light of the exponential growth of cell phones - now including widespread use by children and teenagers. The damaging effects of ELF, if any, might be even greater in the developing brain.

If the link is real, then rates of brain cancers should have increased over the last two decades. Some studies have reported that this is the case, particularly for the most malignant brain cancers. However, other studies have found a stable tumour rate.

“However, the fact that the incidence of gliomas, especially the more malignant varieties, is increasing, warrants action on this issue,” Pawl wrote.

The problem, according to Pawl, is that no other research groups have performed actual studies showing a clear relationship between brain tumours and ELF.

The write-up is scheduled for publication in the November issue of Surgical Neurology.