Thomas S, Kuhnlein A, Heinrich S, Praml G, von Kries R, Radon K. Exposure to mobile telecommunication networks assessed using personal dosimetry and well-being in children and adolescents: the German MobilEe-study. Environ Health 7(1):54 Ahead of print November 4, 2008.
Few epidemiological studies have been conducted on possible association between RF EMF exposure and health outcomes in children and adolescents, and most of these studies relied on self-reported exposure.
The objective of this study was (1) to investigate the potential association between exposure from mobile telecommunication networks (measured with personal dosimeter) and well-being in children and adolescents, and (2) to assess the level of exposure in a general population sample of children and adolescents living in Bavaria (Southern Germany).
Participants (children 8-12 years of age and adolescents 13-17 years of age) were randomly selected from the population registries. All eligible subjects were asked to answer a short questionnaire to assess a potential selection bias. Data on participants’ chronic symptoms (headache, irritability, nervousness, dizziness, fatigue, fear and sleeping problems), sociodemographic characteristics (e.g. income, educational level) and other potential confounders (city/town of residence, environmental worries) were collected using a Computer Assisted Personal Interview. After the interview, a dosimeter (ESM-140 Maschek Electronics) was handed out for a 24-hour measurement. The following 3 frequency ranges were covered by the dosimeter: GSM 900; GSM 1800 (including UMTS 2100 and DECT), and WLAN 2400 frequencies. Measurement interval was 1 second and limit of determination was 0.05 V/m. Only exposure levels during waking hours were summed up and expressed as mean percentage of the ICNIRP reference level. Three times a day during the measurement (morning, noon, evening), the participants were asked to record acute symptoms (headache, irritation, nervousness, dizziness, fatigue and concentration problems) as well as the frequency of mobile phone calls and cordless phone calls in the previous hours.
Overall, 5,870 subjects were eligible for inclusion in the study. Of the eligible subjects, 76% (4,452 persons) answered the short questionnaire and 52% (3,022 persons: 1,498 children and 1524 adolescents) agreed to participate in the field study. In comparison to the non-participants, parents and adolescents who participated in the study tended to have higher level of education, to be more likely mobile phone owners and to be more concerned about possible adverse health effect of RF exposure from mobile telecommunication network.
The median exposure to RF EMF of the children and adolescents participating in the study was estimated to be 0.18% and 0.19% respectively of the ICNIRP reference level.
The strength of this study is the use of personal dosimetry, which allows objective assessment of exposure from all RF sources. Personal dosimetry has some limitations; drawbacks pertinent to the dosimeter used in this study, such as limited ability of the dosimeter to differentiate between the frequencies, difficulties in measurements of night time exposure. Nevertheless, personal dosimetry is considered a better measure of exposure than stationary measurements or estimation (self-reported or calculated) alone.
Because subjects participating in the study tend to be more concerned about possible health effects of RF exposure, a preferential selection of concerned subjects who may overestimate subjective symptoms cannot be ruled out. Due to the objective exposure assessment, a differential exposure misclassification seems to be unlikely. Misclassification concerning chronic symptoms is possible because their assessment was conducted only once. Participants might overestimate their acute symptoms during the measurement day because they might be more aware of them. As the participants were unaware of their objective exposure level, differential misclassification is unlikely. The authors consider that confounding is not a major issue in their study.
Participation in the first study using personal dosimetry to assess exposure to RF from mobile telecommunication networks in children and adolescents was fairly good, and dosimeters were well accepted. The exposure to mobile phone frequencies as assessed by personal dosimeters was far below the current ICNRP reference levels. Personal dosimetry has been proven to be a useful tool for epidemiological studies, including studies in children and adolescents.