| Cross-sectional study to record and evaluate possible adverse health effects due to electromagnetic fields from cell-phone base stations |
|
|
Topic Cross-sectional study to record and evaluate possible adverse health effects due to electromagnetic fields from cell-phone base stations Start 01.07.2003 End 30.06.2006 Project Management University of Bielefeld, University of Mainz, DKFZ Heidelberg, NFO Infratest Munich Objective The strong increase of mobile telecommunication in the past years lead to an increased concern of the population about possible adverse health effects due to the fields of cell-phone base stations. In this regard several health complaints were addressed such as headache, sleep disturbances, nervousness, difficulties in concentration and so on. Up to now the scientific evidence provides no explanation for such an association. The objective of this project was to investigate the hypothesis that cell-phone base station fields can lead to adverse health affects of local residents. The project was subdivided into three parts:
The exposure assessment in part II was carried out in close co-operation with the project 'Determination of exposure in groups of persons investigated within the framework of the project 'Cross-sectional study to record and evaluate the possible adverse health effects from cell-phone base station fields'. The use of personal dosimeters in the in depth survey in part III was done within the project "Addendum to the cross-sectional study on acute health effects caused by fields of mobile phone base stations". Results The pilot study (part I) has successfully demonstrated the feasibility of such a study and the feasibility of geographically coding of the addresses of the homes and base stations. A study design for the main study was developed. In the main survey (part II) a nation-wide survey on subjective symptoms, concerns about base stations and health complaints attributed to base stations was conducted. This was done within the framework of a survey on households of the so-called “Health care Access Panel” that took place between August and November 2004. In this survey 51.444 persons in the age between 14 and 69 years had been asked to complete a self-administered questionnaire. A total of 30.047 individuals filled in the questionnaire. The resulting sample is with respect to the distribution of age, gender and Bundesländer a good approximation of the German population living in private households. A total of 28 % of the population is concerned about the fields of the base stations, 11 % attribute health complaints to the fields of base stations. There was strong north-south gradient, with the greatest concerns in Bavaria and the lowest in Mecklenburg-Vorpommern. Primarily persons in the age between 30 and 50 years, persons with higher graduation, and persons, reporting to live close to base stations, had greater concerns. The results of the nation-wide survey are consistent to the results found in polls on risk perception within the DMF-program. The German Bundesnetzagentur - in agreement with the network operators - provided data on all sites of base stations subject to authorization. This database included data on 51.000 sites and about 280.000 antennas. Based on these data the distance between site of the base station and the home was calculated on the basis of the corresponding geo-coordinates. A rough exposure surrogate was developed that included information on relevant variables with respect to the living-environment, characteristics of the antenna as well as the distance between location of the home and the base station for the year 2004. At that time 47 % of the private households had no base station within 500 m. The cutoff-point of 500 m distance was chosen, because it was assumed that above 500 m there is practically no exposure. But this does not automatically mean that persons living in the surrounding of a base station within a distance of less than 500 m, are more exposed, because distance is no valid exposure metric. The remaining 53 % private households, who are located within 500 m next to a base station, revealed based on the exposure surrogate a median power density of 0,006 mW/m2 , which is far below the limit value. In order to conduct in depth interviews (Part III) a regionally stratified sample of 4.150 individuals of the main survey was drawn. A total of 3.256 individuals from this sample (85 % response rate) filled in the questionnaire. As a result of the planned selection of potentially higher exposed individuals the majority of the participants lived in urban and suburban areas, whereas only 13.5 % of the participants lived in rural areas. The questionnaire of the in depth interviews included several validated instruments to measure self reported health complaints: the “Headache Impact Test” questionnaire HIT to measure headache, the “Pittsburgh Sleep Quality Index” questionnaire PSQI to measure sleep disturbances, the questionnaire “Beschwerdeliste von Zerssen” to measure health complaints in general and the SF-36 questionnaire to measure the quality of life physical and psychological. Moreover the questionnaire included information on potential confounders such as age, gender, living surrounding, use of mobile phones, chronic stress (measured by the questionnaire „Trierer Inventar für Chronischen Stress (TICS)“), anxiety and depression (measured by the questionnaire “Hospital Anxiety and Depression (HADS)). The originally planned use of the exposure surrogate of ECOLOG for risk analyses was postponed for the time being, since without external validation the potential inaccuracies in exposure estimation could not be evaluated finally. Since meanwhile field tested personal dosimeters for exposure assessment had been available, these were used for all individuals of the in depths interviews, who agreed to perform a measurement (n = 1.808). This was done within the DMF-project "Addendum to the cross-sectional study". For 1.500 individuals measurements were successfully performed in the bedroom by use of dosimeters of the company Antenessa. After exclusion of all subjects with missing values in the relevant variables the final dataset for risk analyses included 1.326 individuals. For risk analysis the mean total field exposure in V/m of the fields of the base stations was calculated and dichotomized by the 90 % percentile (0,0993 V/m). Five outcome variables were defined: headache, sleep disturbances, health complaints in general, quality of life physical and psychological. In the regression model potential confounders such as age, sex, living surrounding, use of mobile phones, chronic stress, anxiety and depression were considered. The main results are as follows:
The final report can be downloaded as pdf-file (1.500 KB) in German language. Conclusion The main survey provided the first nationwide information on how the sites of base stations are distributed over Germany and how many private households are in the near surrounding of a base station as well as on prevalence of health complaints, prevalence of concerns about base stations and prevalence of the attribution of health complaints on the base stations. The risk analyses of the in depth survey showed no association between the measured HF-EMF fields of base stations and self reported health complaints. The results of this study as well as the results of the up to now finished experimental studies to this topic in the German telecommunication program suggest no causal relationship between the fields of base stations and acute health complaints among adults. |