No clear evidence of a mobile phone and brain cancer link

By Dr. Ananya Mandal, MDMay 17 2010

Use of mobile phones has been under scrutiny for a while now with many claiming a link between mobile phone use and brain cancer. The mild radioactive waves generated from mobile phones have so far been poorly understood. There are no known mechanisms by which mobile phone radiation could cause cancer. Unlike x-rays, mobile phone radiation is non-ionising, and is too weak to break apart DNA, which is necessary to induce other cancers. However scientists do agree that this radiation might speed up a growing brain tumor.

Now scientists who have conducted the largest study to date called the ‘Interphone study of the safety of mobile phones’ said that it offered no clear evidence of a link with brain cancer. The study is a $24 million study, published in this issue of the International Journal of Epidemiology.

The study covered nearly 13,000 phone users in 13 countries. They also pointed out that greater cancer occurrence in the 10 per cent of people who used their phones most intensively should be approached with caution as they were most likely a result of flaws in the research.

The researchers investigated more than 5,000 men and women aged 30 to 59 with brain tumors and compared them with healthy people. The questionnaires asked the participants to track their mobile phone usage over the last 15 years including the number of calls made and time spent on the phone. The side of the head where the phone handsets was usually held was also checked for any correlation with the tumor sites.

Professor Anthony Swerdlow, from the Institute of Cancer Research, in Sutton, Surrey, said that heavy users have been linked to tumors but this could be an error in the study design. He added that heavy use qualified as 12 hours or more every day. He also pointed out that many brain cancer patients exaggerated their replies to questions related to mobile phone use. This is known as a psychological bias and may have affected the results.

Prof. Elisabeth Cardis of World Health Organization's International Agency for Research on Cancer, or IARC, that organized this study said, “The users in the study were light users compared to today.” Christopher Wild, director of IARC echoed these thoughts saying that the results should be interpreted with caution. He said, “This investigation is a victim of the changing patterns of mobile phone use over the years.” Brain tumors are also slow growing with some taking up to 25 years to manifest. Graham Philips of the Britain-based anti-radiation campaign group Power Watch said, “It is simply too early to detect anything.” Prof. Bernard Stewart, a scientific adviser to Cancer Council Australia said in a similar vein, “In particular insufficient time has passed since mobile phones were introduced to determine whether there is a risk in children.”

The researchers plan to track nearly 250,000 people and their mobile phone use for the next thirty years to come to a valid conclusion in the Cosmos study. U.S. and European regulators are already regulating the amount of radiation that a phone can generate.