The sulfite oxidase Shopper controls neuronal activity by regulating glutamate homeostasis in Drosophila ensheathing glia.

Specialized glial subtypes provide support to developing and functioning neural networks. Astrocytes modulate information processing by neurotransmitter recycling and release of neuromodulatory substances, whereas ensheathing glial cells have not been associated with neuromodulatory functions yet. To decipher a possible role of ensheathing glia in neuronal information processing, we screened for glial genes required in the Drosophila central nervous system for normal locomotor behavior. Shopper encodes a mitochondrial sulfite oxidase that is specifically required in ensheathing glia to regulate head bending and peristalsis. shopper mutants show elevated sulfite levels affecting the glutamate homeostasis which then act on neuronal network function. Interestingly, human patients lacking the Shopper homolog SUOX develop neurological symptoms, including seizures. Given an enhanced expression of SUOX by oligodendrocytes, our findings might indicate that in both invertebrates and vertebrates more than one glial cell type may be involved in modulating neuronal activity.

Asthma prevalence in German Olympic athletes: A comparison of winter and summer sport disciplines.

BACKGROUND: Prevalence of asthma in elite athletes shows very wide ranges. It remains unclear to what extent this is influenced by the competition season (winter vs. summer) or the ventilation rate achieved during competition. The aim of this study was to evaluate prevalence of asthma in German elite winter and summer athletes from a wide range of sport disciplines and to identify high risk groups. METHODS: In total, 265 German elite winter athletes (response 77%) and 283 German elite summer athletes (response 64%) answered validated respiratory questionnaires. Using logistic regression, the asthma risks associated with competition season and ventilation rate during competition, respectively, were investigated. A subset of winter athletes was also examined for their FENO-levels and lung function. RESULTS: With respect to all asthma outcomes, no association was found with the competition season. Regarding the ventilation rate, athletes in high ventilation sports were at increased risk of asthma, as compared to athletes in low ventilation sports (doctors' diagnosed asthma: OR 2.32, 95% CI 1.19-4.53; use of asthma medication: OR 4.46, 95% CI 1.52-13.10; current wheeze or use of asthma medication: OR 2.78, 95% CI 1.34-5.76). Athletes with doctors' diagnosed asthma were at an approximate four-fold risk of elevated FENO-values. CONCLUSIONS: The clinically relevant finding of this study is that athletes' asthma seems to be more common in sports with high ventilation during competition, whereas the summer or winter season had no impact on the frequency of the disease. Among winter athletes, elevated FENO suggested suboptimal control of asthma.

Improved oral bioavailability of human growth hormone by a combination of liposomes containing bio-enhancers and tetraether lipids and omeprazole.

Liposomes for the oral delivery of human growth hormone (hGH) containing bio-enhancers and tetraether lipids were prepared by dual asymmetric centrifugation. Cetylpyridinium chloride (CpCl), d-α-tocopheryl polyethylene glycol 400 succinate, phenylpiperazine, sodium caprate or octadecanethiol were used as permeation enhancers. In vitro data showed that oligolamellar vesicles with average size in the range of 200-250 nm were formed. Performance of the formulations was investigated both ex vivo by confocal microscopy scans of sections of rat small intestine and in vivo by comparing the area under the plasma curve of hGH after oral or subcutaneous (s.c.) application. The microscopic data reveal an interaction between the liposomal formulation and the intestinal mucus layer. Particularly one formulation, which was designed to be mucus penetrative by addition of a high quantity of TPGS 400 and a ζ-potential close to 0 mV, showed a very strong mucus association in the duodenum and jejunum. Vesicles with CpCl 33% (mol/mol) led to a relative hGH bioavailability of 3.4% compared with s.c. control, whereas free hGH administered orally showed a bioavailability of only 0.01%.

FIM, a novel FTIR-based imaging method for high throughput locomotion analysis.

We designed a novel imaging technique based on frustrated total internal reflection (FTIR) to obtain high resolution and high contrast movies. This FTIR-based Imaging Method (FIM) is suitable for a wide range of biological applications and a wide range of organisms. It operates at all wavelengths permitting the in vivo detection of fluorescent proteins. To demonstrate the benefits of FIM, we analyzed large groups of crawling Drosophila larvae. The number of analyzable locomotion tracks was increased by implementing a new software module capable of preserving larval identity during most collision events. This module is integrated in our new tracking program named FIMTrack which subsequently extracts a number of features required for the analysis of complex locomotion phenotypes. FIM enables high throughput screening for even subtle behavioral phenotypes. We tested this newly developed setup by analyzing locomotion deficits caused by the glial knockdown of several genes. Suppression of kinesin heavy chain (khc) or rab30 function led to contraction pattern or head sweeping defects, which escaped in previous analysis. Thus, FIM permits forward genetic screens aimed to unravel the neural basis of behavior.

Testing Skype as an interview method in epidemiologic research: response and feasibility.

INTRODUCTION: Despite its popularity, Skype has not been tested as a tool for epidemiologic research. We examined its feasibility in Germany. METHODS: A population-based sample of young adults was randomly invited to a Skype (n = 150) or a phone interview (n = 150). Response and duration of interviews were analysed to evaluate the feasibility of Skype interviews. RESULTS: Response was low and, with 10 % (95 % CI 5-15 %), even worse among Skype candidates, compared to 22 % (15-28 %) in the phone group. A third of the Skype group asked for being interviewed by phone. Median duration was 34.0 minutes for Skype interviews and 37.0 minutes for phone interviews. CONCLUSIONS: Skype is not yet a feasible tool for data collection in Germany.

Kinesin heavy chain function in Drosophila glial cells controls neuronal activity.

Kinesin heavy chain (Khc) is crucially required for axonal transport and khc mutants show axonal swellings and paralysis. Here, we demonstrate that in Drosophila khc is equally important in glial cells. Glial-specific downregulation of khc by RNA interference suppresses neuronal excitability and results in spastic flies. The specificity of the phenotype was verified by interspecies rescue experiments and further mutant analyses. Khc is mostly required in the subperineurial glia forming the blood-brain barrier. Following glial-specific knockdown, peripheral nerves are swollen with maldistributed mitochondria. To better understand khc function, we determined Khc-dependent Rab proteins in glia and present evidence that Neurexin IV, a well known blood-brain barrier constituent, is one of the relevant cargo proteins. Our work shows that the role of Khc for neuronal excitability must be considered in the light of its necessity for directed transport in glia.

Systematic review of wireless phone use and brain cancer and other head tumors.

We conducted a systematic review of scientific studies to evaluate whether the use of wireless phones is linked to an increased incidence of the brain cancer glioma or other tumors of the head (meningioma, acoustic neuroma, and parotid gland), originating in the areas of the head that most absorb radiofrequency (RF) energy from wireless phones. Epidemiology and in vivo studies were evaluated according to an agreed protocol; quality criteria were used to evaluate the studies for narrative synthesis but not for meta-analyses or pooling of results. The epidemiology study results were heterogeneous, with sparse data on long-term use (≥ 10 years). Meta-analyses of the epidemiology studies showed no statistically significant increase in risk (defined as P < 0.05) for adult brain cancer or other head tumors from wireless phone use. Analyses of the in vivo oncogenicity, tumor promotion, and genotoxicity studies also showed no statistically significant relationship between exposure to RF fields and genotoxic damage to brain cells, or the incidence of brain cancers or other tumors of the head. Assessment of the review results using the Hill criteria did not support a causal relationship between wireless phone use and the incidence of adult cancers in the areas of the head that most absorb RF energy from the use of wireless phones. There are insufficient data to make any determinations about longer-term use (≥ 10 years).

Feasibility of activity-promoting video games among obese adolescents and young adults in a clinical setting.

One component of the recent obesity epidemic is the sedentary behaviour of children and adolescents e.g., use of video games consoles. The new generation of video games requires body movements and might thus increase activity. The aim of this study was to evaluate whether such games could have an effect on physical activity in obese adolescents in a clinical setting. Between March and May 2007 activity-promoting video games ("apvg") were offered to all 84 inpatients (aged 13-28 years) registered in a long-term rehabilitation programme on a voluntary base. Reasons for (non-)attendance were assessed. Frequency and duration of use of the activity-promoting video game sessions were documented. Furthermore, heart rate and activity counts during use of "apvg", endurance training, and strength training were measured. Of 84 inpatients, 51 used the "apvg" at least once (69%) over the study period. The median weekly use of the intervention was 27 min during the first week (range 0-182 min), declining to zero (range 0-74 min) in week four. Mean heart rate during the sessions (mean 115 bpm; 95% confidence interval 108-122 bpm) was similar to the heart rate during strength training (106 bpm; 101-112 bpm). The results indicate that the video games could have an impact on the activity of obese adolescents and young adults. However, as the interest in the devices seems to be too low the suitability of them for weight reduction programmes in young people cannot be ensured.

The impact of exposure to radio frequency electromagnetic fields on chronic well-being in young people--a cross-sectional study based on personal dosimetry.

A possible influence of radio frequency electromagnetic field (RF EMF) exposure on health outcomes was investigated in various studies. The main problem of previous studies was exposure assessment. The aim of our study was the investigation of a possible association between RF EMF and chronic well-being in young persons using personal dosimetry. 3022 children and adolescents were randomly selected from the population registries of four Bavarian cities in Germany (participation 52%). Personal interview data on chronic symptoms, socio-demographic characteristics and potential confounders were collected. A 24-h radio frequency exposure profile was generated using a personal dosimeter. Exposure levels over waking hours were expressed as mean percentage of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference level. Half of the children and nearly every adolescent owned a mobile phone which was used only for short durations per day. Measured exposure was far below the current ICNIRP reference levels. The most reported chronic symptom in children and adolescents was fatigue. No statistically significant association between measured exposure and chronic symptoms was observed. Our results do not indicate an association between measured exposure to RF EMF and chronic well-being in children and adolescents. Prospective studies investigating potential long-term effects of RF EMF are necessary to confirm our results.

Self-reported asthma and allergies in top athletes compared to the general population - results of the German part of the GA2LEN-Olympic study 2008.

BACKGROUND: Prevalence of asthma and allergies in top athletes is high. However, most previous studies did not include a general population comparison group. We aimed to compare the prevalence of asthma, allergies and medical treatment in different groups of German top athletes to the general population. METHODS: Prior to the 2008 Summer Olympic Games, 291 German candidates for participation (65%) completed a questionnaire on respiratory and allergic symptoms. Results were compared to those of a general population study in Germany (n = 2425, response 68%). Furthermore, associations between types of sports and the self-reported outcomes were calculated. All models were adjusted for age, sex, level of education and smoking. RESULTS: Athletes reported significantly more doctors' diagnosed asthma (17% vs. 7%), more current use of asthma medication (10% vs. 4%) and allergic rhinitis (25% vs. 17%) compared to the general population. After adjustment, top athletes only had an increased Odds Ratio for doctor's diagnosed asthma (OR: 1.6; 95% CI 1.1-2.5). Compared to the general population, athletes in endurance sports had an increased OR for doctor's diagnosed asthma (2.4; 1.5-3.8) and current use of asthma medication (1.8; 1.0-3.4). In this group, current wheeze was increased when use of asthma medication was taken into account (1.8; 1.1-2.8). For other groups of athletes, no significantly increased ORs were observed. CONCLUSIONS: Compared to the general population, an increased risk of asthma diagnosis and treatment was shown for athletes involved in endurance sports. This might be due to a better medical surveillance and treatment of these athletes.

Association between exposure to radiofrequency electromagnetic fields assessed by dosimetry and acute symptoms in children and adolescents: a population based cross-sectional study.

BACKGROUND: The increase in numbers of mobile phone users was accompanied by some concern that exposure to radiofrequency electromagnetic fields (RF EMF) might adversely affect acute health especially in children and adolescents. The authors investigated this potential association using personal dosimeters. METHODS: A 24-hour exposure profile of 1484 children and 1508 adolescents was generated in a population-based cross-sectional study in Germany between 2006 and 2008 (participation 52%). Personal interview data on socio-demographic characteristics, self-reported exposure and potential confounders were collected. Acute symptoms were assessed twice during the study day using a symptom diary. RESULTS: Only few of the large number of investigated associations were found to be statistically significant. At noon, adolescents with a measured exposure in the highest quartile during morning hours reported a statistically significant higher intensity of headache (Odd Ratio: 1.50; 95% confidence interval: 1.03, 2.19). At bedtime, adolescents with a measured exposure in the highest quartile during afternoon hours reported a statistically significant higher intensity of irritation in the evening (4th quartile 1.79; 1.23, 2.61), while children reported a statistically significant higher intensity of concentration problems (4th quartile 1.55; 1.02, 2.33). CONCLUSIONS: We observed few statistically significant results which are not consistent over the two time points. Furthermore, when the 10% of the participants with the highest exposure are taken into consideration the significant results of the main analysis could not be confirmed. Based on the pattern of these results, we assume that the few observed significant associations are not causal but rather occurred by chance.

Quality of life in adolescents with headache: results from a population-based survey.

The aim of the investigation was to study the impact of headache on quality of life (QOL) in adolescents in a population-based sample (N = 1047, aged between 13 and 17 years). QOL was assessed using the KINDL-R (Revidierter Kinder Lebensqualitätsfragebogen) questionnaire with its six dimensions. In order to assess potential differences in the impact on QOL according to the type of headache, a stratified analysis was performed. QOL differences compared to the 'no headache' group are presented with adjustment for socio-demographic confounders. Headache at least once per month was reported in 48% of the adolescents and accounted for a small but significant reduction of 2.5 points in the total KINDL-R score, which was mainly caused by a reduction in physical wellbeing by 6.8 points. Adolescents with migraine reported higher reductions in physical wellbeing and total QOL than subjects with tension-type headache (TTH). The size of the reduction in QOL scores was small but similar to that observed for other chronic conditions in adolescents. Headache prevention programs might therefore have an impact on QOL in adolescents.

Exposure to animals and risk of oligoarticular juvenile idiopathic arthritis: a multicenter case-control study.

BACKGROUND: An inverse association between early contact with microbial compounds and respiratory allergies is well established. The protective effect of infant contact with animals was also shown for inflammatory bowel disease (IBD) and systemic lupus erythematosus (SLE). We aimed to test the association between animal contact in infancy and oligoarticular juvenile idiopathic arthritis (OA JIA). METHODS: Parents of children with OA JIA registered at the Hospital for Pediatric Rheumatology in Garmisch-Partenkirchen were asked to complete a questionnaire. Children who underwent strabismus surgery at six referral centers for ophthalmology served as controls. Children age 6 to 18 years born in Germany without malformations were included (238 cases; response 89% and 832 controls; response 86%). Data were analyzed using logistic regression models after adjusting for potential confounders. RESULTS: Neither place of living (urban vs. rural area), living on a farm, nor regular farm animal (adjusted odds ratio 0.79; 95% confidence interval 0.42-1.47) or pet contact (0.79; 0.55-1.14) during infancy were clearly related to case status. Allergic rhinitis was inversely related to OA JIA (0.57; 0.34-0.95).Neither place of living (urban vs. rural area), living on a farm, nor regular farm animal (adjusted odds ratio 0.79; 95% confidence interval 0.42-1.47) or pet contact (0.79; 0.55-1.14) during infancy were related to case status. Allergic rhinitis was inversely related to OA JIA (0.57; 0.34-0.95). CONCLUSIONS: Contact with farm environments in infancy might not be associated with OA JIA. This finding is consistent with previous findings for diabetes mellitus type 1 but contradicts results for IBD and SLE.

The association between use of electronic media and prevalence of headache in adolescents: results from a population-based cross-sectional study.

BACKGROUND: Use of electronic media, i.e. mobile phones, computers, television, game consoles or listening to music, is very common, especially amongst adolescents. There is currently a debate about whether frequent use of these media might have adverse effects on health, especially on headaches, which are among the most-reported health complaints in adolescents. The aim of the present study was to assess associations between frequent use of electronic media and the prevalence of different types of headache in adolescents. METHODS: Data were derived from a population-based sample (n = 1,025, ages 13-17 years). Type of headache (i.e. migraine, tension-type headache, unclassifiable headache) was ascertained by standardized questionnaires for subjects reporting headache episodes at least once per month during the last six months. Duration of electronic media use was assessed during personal interviews. Associations were estimated with logistic regression models adjusted for age group, sex, family condition and socio-economic status. RESULTS: Most of the adolescents used computers (85%), watched television (90%) or listened to music (90%) daily, otherwise only 23% of the participants used their mobile phones and only 25% played with game consoles on a daily basis. A statistically significant association between listening to music and any headache (odds ratio 1.8; 95% confidence interval 1.1-3.1 for 30 minutes per day, 2.1; 1.2-3.7 for 1 to 2 hours per day; 2.0; 1.2-3.5 for 3 hours and longer listening to music per day) was observed. When stratifying for type of headache, no statistically significant association was seen. CONCLUSIONS: Apart from an association between listening to music on a daily basis and overall headache, no consistent associations between the use of electronic media and different types of headache were observed.

Higher prevalence of psychopathological symptoms in adolescents with headache. A population-based cross-sectional study.

BACKGROUND: Headache is commonly voiced by adolescents and is known to be associated with reduced quality of life. Otherwise, there are only limited data regarding associations between different types of headache and psychopathological symptoms in adolescents. OBJECTIVES: Aim of the present study in adolescents was to assess the impact of headache on psychopathological symptoms and whether these differ between types of headache. METHODS: Data were derived from a population-based sample (n = 1047, ages 13-17 years). Type of headache (ie, migraine, tension-type headache, miscellaneous headache) was ascertained for subjects reporting headache episodes at least once per month. Psychopathological symptoms were assessed with the Strengths and Difficulties Questionnaire. The following dimensions were taken into account: emotional symptoms, conduct problems, hyperactivity/inattention, peer problems (these 4 add to the total difficulties score), and prosocial behavior. Associations were estimated with logistic regression models with adjustment for age group, sex, and family situation. RESULTS: Headache at least once per month was reported by 47.8% of the adolescents. Subjects with any headache were found to be at higher risk for emotional symptoms (odds ratio 1.5; 95% confidence interval 1.0-2.2) and hyperactivity/inattention (1.4; 1.0-1.9), resulting in a higher total difficulties score (1.6; 1.1-2.4). While the risk for psychopathological symptoms was not significantly increased in subjects with tension-type headache compared with subjects without headache, significant associations with emotional symptoms were found in subjects with migraine (2.9; 1.3-6.2; total difficulties score: 3.1; 1.4-6.8). Miscellaneous headache was associated with a broad spectrum of psychopathological symptoms: emotional symptoms (1.8; 1.0-3.3), conduct problems (1.6; 1.0-2.6), hyperactivity/inattention (1.9; 1.2-3.1), total difficulties score (2.7; 1.6-5.6). CONCLUSION: Previously reported associations between headache and psychopathological symptoms in adolescents could be confirmed, but might vary with type of headache. As psychopathological symptoms may be a precursor for manifest psychiatric disorders, adolescents particularly with migraine and miscellaneous headache appear to be a vulnerable population.

Exposure to radio-frequency electromagnetic fields and behavioural problems in Bavarian children and adolescents.

Only few studies have so far investigated possible health effects of radio-frequency electromagnetic fields (RF EMF) in children and adolescents, although experts discuss a potential higher vulnerability to such fields. We aimed to investigate a possible association between measured exposure to RF EMF fields and behavioural problems in children and adolescents. 1,498 children and 1,524 adolescents were randomly selected from the population registries of four Bavarian (South of Germany) cities. During an Interview data on participants' mental health, socio-demographic characteristics and potential confounders were collected. Mental health behaviour was assessed using the German version of the Strengths and Difficulties Questionnaire (SDQ). Using a personal dosimeter, we obtained radio-frequency EMF exposure profiles over 24 h. Exposure levels over waking hours were expressed as mean percentage of the reference level. Overall, exposure to radiofrequency electromagnetic fields was far below the reference level. Seven percent of the children and 5% of the adolescents showed an abnormal mental behaviour. In the multiple logistic regression analyses measured exposure to RF fields in the highest quartile was associated to overall behavioural problems for adolescents (OR 2.2; 95% CI 1.1-4.5) but not for children (1.3; 0.7-2.6). These results are mainly driven by one subscale, as the results showed an association between exposure and conduct problems for adolescents (3.7; 1.6-8.4) and children (2.9; 1.4-5.9). As this is one of the first studies that investigated an association between exposure to mobile telecommunication networks and mental health behaviour more studies using personal dosimetry are warranted to confirm these findings.

The association between socioeconomic status and exposure to mobile telecommunication networks in children and adolescents.

A potential association between socioeconomic status (SES) and self-reported use of mobile phones has been investigated in a few studies. If measured exposure to mobile phone networks differs by SES in children, it has not yet been studied. Interview data of 1,481 children and 1,505 adolescents on participants' mobile phone use, socio-demographic characteristics and potential confounders were taken from the German MobilEe-study. Sociodemographic data was used to stratify participants into three "status groups" (low, middle, high). Using a personal dosimeter, we obtained an exposure profile over 24 h for each of the participants. Exposure levels during waking hours were expressed as mean percentage of the reference level. Children with a low SES were more likely to own a mobile phone (OR 2.1; 95% CI: 1.1-3.9) and also reported to use their mobile phone longer per day (OR 2.4; 95% CI: 1.1-5.4) than children with a high SES. For adolescents, self-reported duration of mobile phone use per day was also higher with a low SES (OR: 3.4; 95% CI: 1.4-8.4) compared with a high SES. No association between SES and measured exposure to mobile telecommunication networks was seen for children or adolescents. Mobile phone use may differ between status groups with higher use among disadvantaged groups. However, this does not result in higher overall exposure to mobile telecommunication networks. Whether short duration of own mobile phone use or the small numbers of participants with a low SES are causal, have to be investigated in further studies.

Drosophila Neurexin IV stabilizes neuron-glia interactions at the CNS midline by binding to Wrapper.

Ensheathment of axons by glial membranes is a key feature of complex nervous systems ensuring the separation of single axons or axonal fascicles. Nevertheless, the molecules that mediate the recognition and specific adhesion of glial and axonal membranes are largely unknown. We use the Drosophila midline of the embryonic central nervous system as a model to investigate these neuron glia interactions. During development, the midline glial cells acquire close contact to commissural axons and eventually extend processes into the commissures to wrap individual axon fascicles. Here, we show that this wrapping of axons depends on the interaction of the neuronal transmembrane protein Neurexin IV with the glial Ig-domain protein Wrapper. Although Neurexin IV has been previously described to be an essential component of epithelial septate junctions (SJ), we show that its function in mediating glial wrapping at the CNS midline is independent of SJ formation. Moreover, differential splicing generates two different Neurexin IV isoforms. One mRNA is enriched in septate junction-forming tissues, whereas the other mRNA is expressed by neurons and recruited to the midline by Wrapper. Although both Neurexin IV isoforms are able to bind Wrapper, the neuronal isoform has a higher affinity for Wrapper. We conclude that Neurexin IV can mediate different adhesive cell-cell contacts depending on the isoforms expressed and the context of its interaction partners.

Personal exposure to mobile communication networks and well-being in children--a statistical analysis based on a functional approach.

The MobilEe-study was the first cross-sectional population-based study to investigate possible health effects of mobile communication networks on children using personal dosimetry. Exposure was assessed every second resulting in 86,400 measurements over 24 h for each participant. Therefore, a functional approach to analyze the exposure data was considered appropriate. The aim was to categorize exposure taking into account the course of the measurements over 24 h. The analyses were based on the 480 maxima of each 3 min time interval. Exposure was classified using a nonparametric functional method. Heterogeneity of a sample of functional data was assessed by comparing the functional mode and mean of the distribution of a functional variable. The partition was built within a descending hierarchical method. The resulting exposure groups were compared with categories derived from a standard method, which used the average exposure over 24 h and set the cut-off at the 90th percentile. The functional classification resulted in a splitting of the exposure data into two groups. Plots of the mean curves showed that the groups could be interpreted as children with "low exposure" (88%) and "higher exposure" (12%). These groups were comparable with categories of the standard method. No association between the categorized exposure and well-being was observed in logistic regression models. The functional classification approach yielded a plausible partition of the exposure data. The comparability with the standard approach might be due to the data structure and should not be generalized to other exposures.

Exposure to mobile telecommunication networks assessed using personal dosimetry and well-being in children and adolescents: the German MobilEe-study.

BACKGROUND: Despite the increase of mobile phone use in the last decade and the growing concern whether mobile telecommunication networks adversely affect health and well-being, only few studies have been published that focussed on children and adolescents. Especially children and adolescents are important in the discussion of adverse health effects because of their possibly higher vulnerability to radio frequency electromagnetic fields. METHODS: We investigated a possible association between exposure to mobile telecommunication networks and well-being in children and adolescents using personal dosimetry. A population-based sample of 1.498 children and 1.524 adolescents was assembled for the study (response 52%). Participants were randomly selected from the population registries of four Bavarian (South of Germany) cities and towns with different population sizes. During a Computer Assisted Personal Interview data on participants' well-being, socio-demographic characteristics and potential confounder were collected. Acute symptoms were assessed three times during the study day (morning, noon, evening).Using a dosimeter (ESM-140 Maschek Electronics), we obtained an exposure profile over 24 hours for three mobile phone frequency ranges (measurement interval 1 second, limit of determination 0.05 V/m) for each of the participants. Exposure levels over waking hours were summed up and expressed as mean percentage of the ICNIRP (International Commission on Non-Ionizing Radiation Protection) reference level. RESULTS: In comparison to non-participants, parents and adolescents with a higher level of education who possessed a mobile phone and were interested in the topic of possible adverse health effects caused by mobile telecommunication network frequencies were more willing to participate in the study. The median exposure to radio frequency electromagnetic fields of children and adolescents was 0.18% and 0.19% of the ICNIRP reference level respectively. CONCLUSION: In comparison to previous studies this is one of the first to assess the individual level of exposure to mobile telecommunication networks using personal dosimetry, enabling objective assessment of exposure from all sources and longer measurement periods. In total, personal dosimetry was proofed to be a well accepted tool to study exposure to mobile phone frequencies in epidemiologic studies including health effects on children and adolescents.