By David Liu, Ph.D. and Elizabeth Hutchinson

Tuesday May 31, 2011 (foodconsumer.org) -- The World Health Organization's International Agency for Research on Cancer announced on Tuesday that mobile phones are officially classified as a possible human carcinogen of the Category 2B classification, meaning that they can be as dangerous as car exhaust and the pesticide DDT.

The new classification, which may be viewed as a victory for advocacy groups that have long claimed that using mobile phones can boost the risk of a deadly brain cancer called glioma, came after an eight day meeting where more than 30 experts reviewed about 30 studies.

The electromagnetic radiation given off by the phones is believed to be responsible for the increase in the risk of brain cancer, according to media reports.

But not all studies are consistent. Long-term and high-quality studies tend to associate use of mobile phones with brain cancer. Results from such studies are often cited by advocacy groups to prove the danger associated with the communication device. On the other hand, short-term studies often fail to show such an association, and are often cited by the industry to disprove the notion that using mobile phones would cause anything.

Short-term studies are often sponsored by the industry. Because it takes many years, or a long latency, for a cancer to develop into something that is clinically significant, these studies are often not long enough to reveal any negative impact that mobile phones may have on brain cancer.

Joel M. Moskowitz, director of the UC Berkeley Center for Family and Community Health said many studies are of low quality. When high-quality studies are reviewed, the evidence, he said, reveals that using mobile phones is correlated with the brain cancer risk.

Moskowitz et al. reviewed eight high-quality studies and found mobile phone users were 10 to 30 percent more likely to develop brain cancer when compared with those who did not or rarely used mobile phones. The risk was significantly higher among those who had been using the devices for more than ten years.

The authors published their study in 2009 in the Journal of Clinical Oncology.

Most high quality studies were conducted by Dr. Lennart Hardell, an oncologist in Sweden. He found that ipsilateral mobile phone use (or use of mobile phones on the same side) for ten or more years increases the risk of acoustic neuroma, a benign tumor, by 140 percent and the risk of glioma, a lethal malignancy, by 100 percent.

The media often compares radiofrequency radiation with other radio waves. One thing the media rarely mentions, according to a health observer, is that mobile phones need to release much higher energy in order to send the signal to a cell tower. Because of this, what mobile phone users are exposed to is not the same as what is emitted from a FM radio station.

The U.S. National Cancer Institute updated its website on May 19, 2010 saying that "Research studies have not shown a consistent link between cell phone use and cancer. A large international study (Interphone) published in 2010 found that, overall, cell phone users have no increased risk for two of the most common types of brain tumor?lioma and meningioma."

Moskowitz reportedly told Businessweek that such a study may be biased.