電磁波敏感症(IEI-EMF)：從全球的流行變化趨勢到個人的電磁場暴露

Electromagnetic hypersensitivity refers to health effects attributed to electromagnetic field (EMF) exposure. These symptoms have been officially named “idiopathic environmental intolerance attributed to electromagnetic fields” (IEI-EMF) by the World Health Organization. Because of the growing use of cell phones, IEI-EMF has become a global public health concern. A nationwide telephone survey in 2007 in Taiwan showed that the prevalence rate of IEI-EMF was 13.3%, which is higher than rates in previous studies. We conducted a survey using the same method, and found that the rate had declined to 4.6% in 2012. We also found a declining global prevalence in our literature review. Because media reports may encourage readers to attribute their symptoms to EMF, this change might be related to media coverage. We searched for articles indexed in the largest newspaper database in Taiwan to evaluate the association between media coverage and the prevalence of IEI-EMF. The number of newspaper articles related to EMF and IEI-EMF increased from 2005 to 2007 and then has been decreasing until 2012, which is compatible with the change in the prevalence of IEI-EMF. We also assessed the effects of other potential affecting factors, such as the density of mobile phone base stations, the number of mobile phone users, total mobile phone calling time, and the number of text messages sent through mobile phones. We found that all of these potential factors increased in Taiwan from 2007 to 2012. The result of an environmental EMF exposure study cannot be used to explain the condition of individual exposure. Therefore, we conducted a double-blind provocation study to test whether EMF exposure affects blood pressure (BP) and heart rate variation (HRV), and to verify whether IEI-EMF sufferers are able to accurately discriminate between sham and real EMF exposures. 58 self-reported IEI-EMF sufferers and 92 controls were exposed to base station-like signal in a double-blind and randomized experimental procedure. The BP and HRV of individuals in both groups remained unaffected by EMF exposure. Neither the IEI-EMF group nor controls could accurately identify the provocation status of their sessions. Our study indicated that short-term mobile phone signal exposure does not affect BP and HRV and that none of the participants could accurately detect EMF exposure. In conclusion, the results of our study support the hypotheses that risk perception of EMF might be affected by media reports, and that exposure to short-term, low intensity, base station-like EMF does not affect BP and HRV.