Author: K Sri N.
Conference/Journal: Indian J Physiol Pharmacol.
Date published: 2015 Apr-Jun
Other: Volume ID: 59 , Issue ID: 2 , Pages: 125-35 , Word Count: 397
It is documented that electromagnetic emissions from mobile phones can interfere with brain's signal processing activity due to their oscillatory similitude to the inherent rhythms of the brain, akin to "electromagnetic interference" observed while using mobile phones in aeroplanes. At high power density levels, thermal effects occur, some of which can be attributed to heat induced stress mechanisms. The less understood non-thermal effects occur at low radio frequency/microwave power density levels and are not accompanied by any body temperature rise. The safety standards set by international agencies are based on thermal effects. For the mobile phones, ICNIRP 1998 guidelines restrict spatial peak of microwave exposure to 2 W/Kg SAR values averaged over 10 g of tissue for 6 minutes. Some of the reported electromagnetic radiation (EMR) induced adverse effects are brain tumours, male infertility and immune dysfunction with increased susceptibility to infections. Pathophysiological mechanisms of interaction of EMR at plasma membrane are calcium efflux from cell membranes, increased expression of stress proteins, influence on channels/gap junctions in cell membrane, overproduction of reactive oxygen species, ornithine decarboxylase activation, reduction in melatonin levels, decrease in protein kinase C activity, damage to DNA and change in gene expression in brain cells and altered blood-brain barrier. There are equal number of conflicting reports in literature regarding EMR exposure and brain tumours. A comprehensive review concludes "overall the studies published to date do not demonstrate an increased risk within approximately 10 years of use for any tumour of the brain or any other head tumour." Another review summarises that there is "enough data to convince that long-term exposure to low intensity EMR below the ICNIRP guidelines can promote cancer development". However the time limit for exposure has been suggested as more than 10 years. For conducting epidemiological studies, some of the difficulties experienced are obtaining unexposed controls or cohorts, follow up of the cohorts, actual dose measurement for exposure assessment in case-control studies, inaccuracy, recall bias and selective non response in recall of phone use by mobile phone users, long induction times, long latencies (the effects we observe now are of analogue phones that are no longer used ) and the rarity of observed malignancies, variable ways of using the phone by the user i.e. left or right ear, head sets/speaker/blue tooth etc. Large-scale epidemiological studies should employ personal MW dosimeters for strict dose measurement and for interpreting actual tissue exposure.