Abstract
The association between non-specific physical symptoms (NSPS) such as headache, fatigue, nausea and sleep problems and exposure to electromagnetic fields (EMF) in the general population has been a subject of ongoing scientific debate and public concern. A limited number of epidemiological studies has used surrogates of actual field strength, while
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none of those studies has combined self-reported and general practice (GP)-registered data on NSPS. Evidence from experimental studies suggests that symptoms tend to occur when participants believe they are exposed, irrespective of whether their belief is accurate or not. There are no published epidemiological studies that jointly investigated actual and perceived exposure in combination with psychological factors. The thesis comprised two systematic reviews (Chapters 2, 4), a pilot epidemiological study (n=3611) (chapter 3) and the central study carried out in 2011 (Chapters 5, 6), which combined a health survey of adult (≥18) participants (n=5933) with the electronic medical records of the respondents as registered by general practitioners. The systematic review and meta-analysis of epidemiological studies (Chapter 2) showed no evidence for an association between frequency and severity of NSPS and higher levels of actual measured or modelled EMF exposure, while an association with perceived exposure was more distinct. Studies with a higher risk of bias, mainly regarding exposure assessment, sample selection and adjustment for confounders, tended to report more significant symptomatic effects. Chapter 3 demonstrated that increased report of NSPS was associated with self-reported environmental sensitivity, perceived proximity to base stations and high-voltage overhead power lines, lower perceived control and increased avoidance (coping) behavior. No significant association was found between symptom report and actual (geo-coded) distance to base stations or power lines. In Chapter 4, the case definition criteria to identify individuals with IEI-EMF in epidemiological research were summarized: 1) Self-report of being (hyper)sensitive to EMF. 2) Attribution of NSPS to at least one EMF source. 3) Absence of medical or psychiatric/psychological disorder capable of accounting for these symptoms 4) Occurrence of symptoms during or soon after the individual perceives an exposure source or exposed area. Chapter 5 showed that environmentally sensitive individuals experienced poorer health, increased illness behavior (especially related to alternative therapies), more negative symptom perceptions and more severe NSPS, compared to non-(environmentally) sensitive participants. It was also concluded that the number and duration of self-reported NSPS were important components of symptom severity in the investigated groups. Chapter 6 employing various exposure proxies, provided no convincing evidence for an association between everyday life RF-EMF exposure and NSPS and sleep quality in the general population. A few associations were observed between electric appliances and symptoms. Perceived exposure, perceived control and avoidance coping were independently associated with the examined health outcomes. In addition to the cross-sectional design of the study, a number of limitations were also acknowledged, primarily related to the characterization of actual EMF exposure; a highly complex issue that remains a challenge for epidemiological studies internationally.
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