Unfortunately, at least some of these studies fail to meet many of the criteria for good research, thus weakening their scientific value further. Therefore, more well-controlled studies are required to validate conclusions as to whether exposure to cell phones influences cognition, especially in the long term. Nevertheless, most of the reported effects are small as long as the radiation intensity is within the reasonable nonthermal range and its duration does not exceed common exposure for users.
In 2002 the U.K. published a brochure recommending that children and young people should use cell phones as little as possible. A year later Thailand¿s interior minister considered a ban on their use by children. But in 2004 the Health Council of the Netherlands, unable to find convincing scientific data demonstrating a difference between children and adults in the absorption of electromagnetic energy, found no reason to recommend limiting child use.
I was unaware of solid scientific evidence to support such concerns, but given that my cell phone was one of my infant son¿s favorite toys, I let him play with it only after I made sure it had been switched off. A precautionary approach remains justifiable because detrimental effects cannot be ruled out completely. Now that my son has learned how to turn my phone back on, however, I remind myself that when these phones are used in public, the indirect health effects sustained by vexed passersby may well outweigh the direct neural disturbances on their users.
Still, a very recent report associates increased risk of malignant brain tumor with long-term cell phone use. This report does not represent a new study but is instead a combined analysis of two population-based case control studies published in 2003 and 2005. The findings from this report are difficult to interpret because the experimental design is notably different from that of previous studies of long-term cell phone use and brain cancer. For example, the exposure assessment was mostly performed using mailed questionnaires; multiple confounding factors were not addressed, and a single statistical adjustment corrected for the year of diagnosis only. In addition, a compelling mechanism of action is absent and it is unclear what physiological process could explain such a decisive correlation. Finally, the results are incongruent with most animal studies, which show no relationship between cell phone exposure and brain cancer.
Of course, cell phones are not the only form of radiation exposure, simply an example of popular technology. And, as with TMS, some exposures may actually be helpful in certain contexts. Magnetic resonance imaging (MRI) of the living brain uses an externally imposed magnetic field. Preliminary findings suggest that bipolar-disorder patients¿ moods improve immediately after they undergo a specific MRI procedure. It is possible that this effect works in a way similar to that of TMS on symptoms of depression, but further investigation is warranted.