A World Health Organisation (WHO) panel has concluded that use of mobile phones are “possibly carcinogenic,’’ putting the devices in a category of 266 existing items in the 'possibly' category such as pesticides, coconut oil diethanolamine condensate, Diesel fuel, dry cleaning chemicals, lead, cobalt and bitumen as a potential threat to human health.

The WHO/International Agency for Research on Cancer (IARC) has classified radiofrequency electromagnetic fields as possibly carcinogenic to humans (Group 2B), based on an increased risk for glioma, a malignant type of brain cancer, associated with wireless phone use [237,913 new cases of brain cancers (all types combined) occurred around the world in 2008 (gliomas represent 2/3 of these). Source: Globocan 2008].

Among research which the scientists reviewed was the 2010 13-country study called Interphone - - the largest and longest study of the link between mobile phone use and brain tumours, that found no overall increased risk, but reported that participants with the highest level of phone use had a 40% higher risk of glioma. (However, even if the elevated risk is confirmed, gliomas are relatively rare and individual risk remains minimal.)

The panel said that over the last few years, there has been mounting concern about the possibility of adverse health effects resulting from exposure to radiofrequency electromagnetic fields, such as those emitted by wireless communication devices. The number of mobile phone subscriptions is estimated at 5bn globally .

From May 24–31 2011, a Working Group of 31 scientists from 14 countries had been meeting 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, which will be the fifth volume in this series to focus on physical agents, after Volume 55 (Solar Radiation), Volume 75 and Volume 78 on ionizing radiation (X-rays, gamma-rays, neutrons, radio- nuclides, and Volume 80 on non-ionizing radiation (extremely low-frequency electromagnetic fields).

The IARC Monograph Working Group discussed the possibility that these exposures might induce long -term health effects, in particular an increased risk for cancer. This has relevance for public health, particularly for users of mobile phones, as the number of users is large and growing, particularly among young adults and children.

The IARC Monograph Working 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.

International experts shared the complex task of tackling the exposure data, the studies of cancer in humans, the studies of cancer in experimental animals, and the mechanistic and other relevant data.

Results: IARC said theevidence 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 mentioned above was similarly judged inadequate. The Working Group did not quantify the risk; however, one study of past cell phone use (up to the year 2004), showed a 40% increased risk for gliomas in the highest category of heavy users (reported average: 30 minutes per day over a 10-year period).

Conclusions: Dr Jonathan Samet (University of Southern California, USA), overall chairman of 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. "

The Working Group considered hundreds of scientific articles; the complete list will be published in the Monograph. IARC said it is noteworthy to mention that several recent in-press scientific articles resulting from the Interphone study were made available to the panel shortly before it was due to convene, reflecting their acceptance for publication at that time, and were included in the evaluation.

A concise report summarising the main conclusions of the IARC Working Group and the evaluations of the carcinogenic hazard from radiofrequency electromagnetic fields (including the use of mobile telephones) will be published in The Lancet Oncology in its July 1 issue, and in a few days online.