The World Health Organisation's International Agency for Research on Cancer (IARC) has recently classified radiofrequency electromagnetic fields as “possibly carcinogenic to humans (Group 2B).” The classification is based on increased risk for glioma from increased wireless phone use over a period of time. Glioma is a type of brain cancer that begins in the glial cells that surround and support the nerve cells. The grouping under 2B puts mobile phone use alongside 240 other agents, including low-level magnetic fields, for which evidence of harm is uncertain. IARC has stated that the evidence of carcinogenicity among mobile phone users is “limited.” Though it has found a positive association between mobile phone use and cancer to be “credible,” it notes that the possibility of chance, bias, or other factors playing a role “cannot be ruled out.” Interestingly, the carcinogenic labelling comes a year after the largest case-control study of the problem — WHO's Interphone study, undertaken in 13 countries, involving users with at least ten years' exposure, and published in the International Journal of Epidemiology — found “no increase in risk of glioma with mobile phone use.” Some large-scale studies undertaken in the past have come up with mixed findings. While a 2001 and 2006 follow-up Danish study found no relationship between risk of cancer and long-term mobile phone use among more than 400,000 people, a 2009 Swedish study found increased risk of brain cancer among those who used mobile phones for at least ten years, especially those below 20 years of age.

Unlike gamma rays and X-rays, cell phone radiation is non-ionizing in nature. Radiowaves are not energetic enough to remove electrons or ionize atoms or molecules and hence cannot directly damage cellular DNA. No mechanism has so far been found that can possibly explain the manner in which non-ionizing radiation can cause cumulative effect or DNA damage due to exposure over a period of time. Yet a precautionary approach needs to be adopted, considering the growing number of people, especially very young children, using the phone repeatedly and for long durations. Though countries have already set the upper limit to radiation from mobile phones to reduce the amount of non-ionizing radiation and heat absorbed by tissues, a further lowering of permissible levels may be required. Until such time definite answers are available, it is best that older children are encouraged to restrict mobile phone use and very young children asked to avoid its use. Adults can rely more on texting options and resort to hands-free modes of using mobile phones.

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