June 16, 2011

Study Casts Doubt On Mobile Phone Use And Tumors

A new study casts doubts on recent claims that mobile phones increase the risk of brain tumors, finding that tumors among mobile phone users are not within range of most of the radiation emitted from the devices.

The research found that people who had used mobile phones for the longest amount of time were no more likely to experience tumors located within 2 inches of the phone, where "90 percent of the radiation" is emitted, said study author Dr. Suvi Larjavaara from the University of Tampere in Finland in an interview with Reuters.

These findings follow a recent recommendation by the World Health Organization that cell phones be classified as "possibly carcinogenic".

The organization had previously said there was no established evidence for a link between cell phone use and cancer, but that it based its latest findings upon a review of currently available scientific evidence.

However, Larjavaara cautioned that the results of the Finnish study are not conclusive since cancer can take years to develop, and only 5 percent of the people included in the study had been using mobile phones for at least 10 years.

Larjavaara also acknowledged that the findings contradict the WHO's latest announcement, which placed cell phone use in the same cancer risk category as coffee and chloroform.

"Our evidence does not support the connection, but obviously a majority does," Larjavaara told Reuters.

The overall evidence on the matter remains mixed.  Last year, a study involving 13,000 cell phone users over 10 years was inconclusive about whether the mobile devices cause brain tumors. Meanwhile, another study published last February suggested that mobile phone use could alter brain cell activity.

One particular challenge in studying the risks of cell phone use is that people do not often remember how much time they spend on their mobile phone.  Larjavaara took the approach of examining the location of tumors, reasoning that a cluster of tumors close to the phones would implicate the devices.

The researchers examined 888 brain tumors diagnosed between 2000 and 2004, and mapped the precise location within the brain relative to where a person would place a cell phone while talking.

The Finnish study was one of the reports included in the WHO's recent assessment of cancer risk from mobile phone use, along with two others by Dr. Elisabeth Cardis at the CREAL-Center for Research in Environmental Epidemiology in Spain.

Cardis told Reuters that she and her team also looked at tumor location among cell phone users, and developed a way to calculate the amount of energy present at the actual tumor.   Among other factors, the calculations took into account the characteristics of the phone and network.  Their analysis found that tumors in long-term mobile phone users did indeed occur more frequently in locations with higher exposure from the devices, Cardis explained.

The current study considered the entire mobile phone as a radiation source, since many devices have an integrated antenna, and therefore measured the distance of tumors from any point on the phone.

However, Cardis called this definition of exposure "overly simplistic" because previous studies have found that the most exposed area is typically located around the ear.

"I expect there is substantial misclassification of exposure in the analyses published in the American Journal of Epidemiology, and hence it is not possible to draw conclusions about the presence or absence of a risk," she said.

Some 5 billion mobile phones are currently in use worldwide.

The study was published online May 24, 2011 in the American Journal of Epidemiology.


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