Cell phone not linked to brain tumor risk: Study

Results of a 30-year long trial embarked on to study the incidence of brain tumor during the span when cell phone use became widely prevalent suggest no significant increase in the brain tumor diagnoses, researchers report in the Dec. 3 online edition of the Journal of the National Cancer Institute.

"If mobile phones were to cause brain tumors we would expect to see a sudden rise in the number of brain tumors at some point in time, and we don't see it" study’s lead researcher, Isabelle Deltour, from the Institute of Cancer Epidemiology at the Danish Cancer Society in Copenhagen averred.

"Either it means that mobile phones don't cause brain tumors or it means that we don't see it yet or we don't see it because the increase is too small to be observed in this population, or it is a risk that is limited to a small subgroup of the population" she added.

The study of 60,000 tumor cases
Researchers examined nearly 60,000 brain tumor cases, primarily gliomas and meningioma, diagnosed over a period of 30 years--from 1974 to 2003-- among a total data base of 16 million adults.

Hailing from the regions of Denmark, Finland, Norway and Sweden, the study subjects were aged between 20 and 79 years.

Findings of the study
The study period saw an annual increase in the incidence of gliomas by 0.5 percent in men and 0.2 percent in women. Similarly, the annual incidence for meningioma soared by 0.8 percent among men and 3.8 percent among women.

However, researchers found that the incidence of brain tumors cases remained stable, decreased, or gradually increased over the 30-year study period.

Also, they found no significant increase in the incidence of brain tumor cases between 1998 and 2003, the period when cell phone use became most prevalent.

The unidentified link
The radio frequency electromagnetic fields emitted from mobile phones is often thought as the culprit behind a heightened brain cancer risk. However, a biological mechanism that could explain the potential effects of mobile phone radiation on its users has not been identified so far.

Need for further research
Although the results of the study extend those of the previous studies held in this matter, researchers call for more work in the area.

"Overall, the scientific evidence tells us that using mobile phones for less than 10 years does not increase the risk of cancer and this large study supports that conclusion" Dr Alison Ross, Cancer Research UK's senior science information officer stated.

"However, brain tumors often take a very long time to develop so we will need to look for any future changes in incidence rates to see if mobile phones could pose any longer-term risks," Ross emphasized.