Over the last few years, there has been mounting concern about the possibility of adverse health effects resulting from exposure to radiofrequency elecromagnetic fields, such as those emitted by wireless communication devices. The number of mobile phone subscriptions is estimated at 5 billion globally. There were 237,913 new cases of brain cancers (all types combined) reported around the world in 2008 (the last year for which statistics are available. Gliomas represent two-thirds of these cases.

From May 24–31, a working group of 31 scientists from 14 countries met at IARC in Lyon, France, to assess the potential carcinogenic hazards from exposure to radiofrequency electromagnetic fields. These assessments will be published as Volume 102 of the IARC Monographs, and in the July 1 issue of The Lancet Oncology.

The IARC Monograph Working Group discussed the possibility that these exposures might induce long‐term health effects, in particular an increased risk for cancer. The group decided to classify the risk from cell phones as 2B, “possibly carcinogenic to humans.” This category is used for agents for which there is limited evidence of carcinogenicity in humans and less than sufficient evidence of carcinogenicity in experimental animals. It also may be used when there is inadequate evidence of carcinogenicity in humans but there is sufficient evidence of carcinogenicity in experimental animals. The group discussed and evaluated the available literature on the following exposure categories involving radiofrequency electromagnetic fields:

  • Occupational exposures to radar and to microwaves;
  • Environmental exposures associated with transmission of signals for radio, television and wireless telecommunication; and
  • Personal exposures associated with the use of wireless telephones.

The evidence was reviewed critically, and overall evaluated as being limited among users of wireless telephones for glioma and acoustic neuroma, and inadequate to draw conclusions for other types of cancers. The evidence from the occupational and environmental exposures also was judged inadequate. The working group did not quantitate the risk. However, one study of past cell phone use (up to the year 2004), showed a 40 percent increased risk for gliomas in the highest category of heavy users (reported average: 30 minutes per day over a 10‐year period).

Dr. Jonathan Samet of the University of Southern California, who chaired the working group, indicated that, “The evidence, while still accumulating, is strong enough to support a conclusion and the 2B classification. The conclusion means that there could be some risk, and therefore we need to keep a close watch for a link between cell phones and cancer risk.”

“Given the potential consequences for public health of this classification and findings,” said IARC Director Christopher Wild, “it is important that additional research be conducted into the long‐term, heavy use of mobile phones. Pending the availability of such information, it is important to take pragmatic measures to reduce exposure such as hands‐free devices or texting.”