Representative survey on idiopathic environmental intolerance attributed to electromagnetic fields in Taiwan and comparison with the international literature.

BACKGROUND: Electromagnetic hypersensitivity refers to health effects attributed to electromagnetic fields (EMF) exposure and has been formally 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 survey in 2007 in Taiwan showed that the prevalence rate of IEI-EMF was 13.3%, which is higher than rates in studies conducted previously. The survey also found that the rate was higher in women.

METHODS: To evaluate whether the prevalence rate of IEI-EMF is increasing and to verify the higher risk in women, we conducted a nationwide questionnaire survey using the same methods as the 2007 survey to assess the change in the prevalence rate of IEI-EMF in Taiwan. We also conducted a review of the literature and a meta-analysis to evaluate the changes in the prevalence rate around the world.

RESULTS: On the basis of the representative sample of 3303 participants, we found that the prevalence rate of IEI-EMF in Taiwan declined from 13.3% to 4.6% over a period of 5 years. The literature review also found the prevalence rates in other countries to be decreasing, instead of increasing as predicted previously. The meta-analysis of the data from the literature showed that women are more likely to have IEI-EMF than men, with an odds ratio of 1.19 (95% confidence interval: 1.01-1.40).

CONCLUSIONS: We found the prevalence rate of IEI-EMF has been declining, instead of increasing as predicted previously. Women are more likely to report having IEI-EMF than men. Further studies to explore the causes leading to the declines may help the public, scientific community, and government deal with idiopathic intolerance to other environmental exposures.