Berg-Beckhoff G, Blettner M, Kowall B, Breckenkamp J, Schlehofer B, Schmiedel S, Bornkessel C, Reis U, Potthoff P, Schüz J. (2009). Mobile phone base stations and adverse health effects: phase 2 of a cross-sectional study with measured radiofrequency electromagnetic fields. Occup Environ Med 66(2):124-130.
Much of the perception of health risks surrounding radiofrequency electromagnetic fields (RF-EMF) is based on anecdotal reports from individuals attributing adverse health events to EMF sources. To explore how these health complaints relate to true RF-EMF exposure and to the proximity of mobile phone base stations, a comprehensive population-based cross-sectional study in Germany was conducted. In phase 1 of the study, health complaints and the vicinity of base stations was investigated.
In the present article, phase 2 of the study, the authors investigated the association between health disturbances and measured RF-EMF in participants’ residences.
From a nationwide survey of 51,444 people, a total of 30,047 (58%) filled-in the questionnaire. Participants of a sub-sample were chosen from German urban regions (such as Berlin, Hamburg, etc.) because estimates in phase 1 had shown that the RF-EMF exposure was higher compared to rural areas. From these regions, 4,150 individuals were contacted. Dosimetric measurements in households were taken between March and August 2006. Standardized health questionnaires included the 18-item Pittsburgh Sleep Quality Index (PSQI), the six-item Headache Impact Test (HIT-6), the 24-item list of psychosomatic complaints, the 36-item profile of mental and physical health (SF-36), and a short version of the Trier Inventory of Chronic Stress. For the exposure assessment, RF-EMF dosimeters were used. Measurements were carried out on different positions on the beds of the participants. To characterize exposure to RF-EMFs from the mobile phone base stations, a dichotomous variable was created (exposed/non-exposed), based on the root mean square of multiple field values for each person. The cut-off point for categorization of the exposure was the 90th centile of the distribution of the mean total field values (0.1 V/m or 0.029 mW/m2).
Of 4,150 people asked to participate, 3,526 (85%) responded to the questionnaire (response rate 85.0%), and from these, 1,808 (51%) agreed to dosimetric measurements in their bedrooms. Following certain exclusions, exposure data was available on 1,326 participants. Of these, 8.8% attributed adverse health effects to mobile phone base stations, and 27.1% were concerned about exposure but did not attribute their health complaints to RF-EMF exposure from the base stations. For all the health questionnaires, no differences in median scores were seen comparing exposed versus non-exposed. Differences were, however, observed across groups of risk perception. For example, participants who attributed adverse health effects to mobile phone base stations had more actual health disturbances, compared with those who were merely “concerned” about the base stations. Adjusting for common confounders (age, sex, schooling, stress, and mobile phone use) did not alter the results.
Discussion and conclusion
The authors acknowledged certain limitations with their data, such as the confinement of the RF-EMF measurements to daylight hours, to beds, and to a single session. The authors also cautioned that study selection was not random – a more highly exposed population was selected. In interpreting their results, the authors identified two hypotheses: people with persisting health disturbances attribute symptoms to the mobile phone base station in an effort to identify a cause, and people with high levels of stress regarding a mobile phone base station as a hazard leads to the promotion of health disturbances. Overall, the measurements of RF-EMF exposure from base stations were far below legislated guidelines. The authors conclude that, nevertheless, the worries and health complaints of people living close to mobile phone base stations need to be taken seriously, and that improvements in risk communication are called for.