Residential characteristics and radiofrequency electromagnetic field exposures from bedroom measurements in Germany.

The objectives of this study were to assess total exposure to radiofrequency electromagnetic fields (RF-EMF) in bedrooms and the contribution of different radioservices (FM radio, analogue TV and DVB-T, TETRA, GSM900 downlink, GSM1800 downlink, UMTS downlink, DECT, and wireless LAN and blue tooth) to the total exposure. Additional aims were to describe the proportion of measuring values above the detection limit of the dosimeters and to characterize the differences in exposure patterns associated with self-reported residential characteristics. Exposure to RF sources in bedrooms was measured using Antennessa(®) EME Spy 120 dosimeters in 1,348 households in Germany; 280 measures were available for each frequency band per household. Mean electrical field strengths and power flux densities were calculated. Power flux densities allow the calculation of proportions of different radioservices on total exposure. Exposure was often below the detection limit (electrical field strength: 0.05 V/m) of the dosimeter. Total exposure varied, depending on residential characteristics (urban vs. rural areas and floor of a building the measurement took place). Major sources of exposure were cordless phones (DECT standard) and wireless LAN/blue tooth contributing about 82% of total exposure (20.5 µW/m(2)). Exposure to RF-EMF is ubiquitous, but exposure levels are-if at all measurable-very low and far below the ICNIRP's exposure reference levels.

Primary brain tumours and specific serum immunoglobulin E: a case-control study nested in the European Prospective Investigation into Cancer and Nutrition cohort.

BACKGROUND: Case-control studies suggest that patients with allergic diseases have a lower risk of developing glioma but not meningioma or schwannoma. However, those data can be differentially biased. Prospective studies with objective measurements of immunologic biomarkers, like immunoglobulin E (IgE), in blood obtained before cancer diagnosis could help to clarify whether an aetiological association exists. METHODS: The present case-control study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC) measured specific serum IgE as a biomarker for the most common inhalant allergens in 275 glioma, 175 meningioma and 49 schwannoma cases and 963 matched controls using the ImmunoCAP specific IgE test. Subjects with an IgE level ≥0.35 kUA/l (kilo antibody units per litre) were classified as sensitized by allergens. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by adjusted conditional logistic regression models for each tumour subtype. The effect of dose-response relationship was assessed in five increasing IgE level categories to estimate P-values for trend. RESULTS: The risk of glioma was inversely related to allergic sensitization (OR = 0.73; 95% CI 0.51-1.06), especially pronounced in women (OR = 0.53; 95% CI 0.30-0.95). In dose-response analyses, for high-grade glioma, the lowest OR was observed in sera with the highest IgE levels (P for trend = 0.04). No association was seen for meningioma and schwannoma. CONCLUSION: The results, based on serum samples prospectively collected in a cohort study, provide some support for the hypothesis that individuals with allergic sensitization are at reduced risk of glioma and confirm results from previous case-control studies.

Mobile phone base stations and adverse health effects: phase 1 of a population-based, cross-sectional study in Germany.

OBJECTIVE: The aim of this first phase of a cross-sectional study from Germany was to investigate whether proximity of residence to mobile phone base stations as well as risk perception is associated with health complaints. METHODS: The researchers conducted a population-based, multi-phase, cross-sectional study within the context of a large panel survey regularly carried out by a private research institute in Germany. In the initial phase, reported on in this paper, 30,047 persons from a total of 51,444 who took part in the nationwide survey also answered questions on how mobile phone base stations affected their health. A list of 38 health complaints was used. A multiple linear regression model was used to identify predictors of health complaints including proximity of residence to mobile phone base stations and risk perception. RESULTS: Of the 30,047 participants (response rate 58.6%), 18.7% of participants were concerned about adverse health effects of mobile phone base stations, while an additional 10.3% attributed their personal adverse health effects to the exposure from them. Participants who were concerned about or attributed adverse health effects to mobile phone base stations and those living in the vicinity of a mobile phone base station (500 m) reported slightly more health complaints than others. CONCLUSIONS: A substantial proportion of the German population is concerned about adverse health effects caused by exposure from mobile phone base stations. The observed slightly higher prevalence of health complaints near base stations can not however be fully explained by attributions or concerns.

Mobile phone base stations and adverse health effects: phase 2 of a cross-sectional study with measured radio frequency electromagnetic fields.

OBJECTIVE: The aim of the cross-sectional study was to test the hypothesis that exposure to continuous low-level radio frequency electromagnetic fields (RF-EMFs) emitted from mobile phone base stations was related to various health disturbances. METHODS: For the investigation people living mainly in urban regions were selected from a nationwide study in 2006. In total, 3526 persons responded to a questionnaire (response rate 85%). For the exposure assessment a dosimeter measuring different RF-EMF frequencies was used. Participants answered a postal questionnaire on how mobile phone base stations affected their health and they gave information on sleep disturbances, headaches, health complaints and mental and physical health using standardised health questionnaires. Information on stress was also collected. Multiple linear regression models were used with health outcomes as dependent variables (n = 1326). RESULTS: For the five health scores used, no differences in their medians were observed for exposed versus non-exposed participants. People who attributed adverse health effects to mobile phone base stations reported significantly more sleep disturbances and health complaints, but they did not report more headaches or less mental and physical health. Individuals concerned about mobile phone base stations did not have different well-being scores compared with those who were not concerned. CONCLUSIONS: In this large population-based study, measured RF-EMFs emitted from mobile phone base stations were not associated with adverse health effects.

Environmental risk factors for sporadic acoustic neuroma (Interphone Study Group, Germany).

The only known risk factor for sporadic acoustic neuroma is high-dose ionising radiation. Environmental exposures, such as radiofrequency electromagnetic fields and noise are under discussion, as well as an association with allergic diseases. We performed a population-based case-control study in Germany investigating these risk factors in 97 cases with acoustic neuroma, aged 30 to 69 years, and in 194 matched controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated in multiple logistic regression models. Increased risks were found for exposure to persistent noise (OR=2.31; 95% CI 1.15-4.66), and for hay fever (OR=2.20; 95% CI 1.09-4.45), but not for ionising radiation (OR=0.91; 95 % CI 0.51-1.61) or regular mobile phone use (OR=0.67; 95% CI 0.38-1.19). The study confirms results of recently published studies, although the pathogenetic mechanisms are still unknown.

Association between brain tumors and menopausal status.

BACKGROUND: Several lines of evidence have implicated female hormones in the etiology of human brain tumors, meningiomas in particular. PURPOSE: To investigate the relationship between brain tumor development and the hormonal changes manifested during pregnancy and menopause, we analyzed data from female participants in a population-based case-control study of adult brain tumors. This study was conducted in 1987-1988 in the Rhein-Neckar-Odenwald area of the Federal Republic of Germany. METHODS: The study population consisted of 127 women with meningiomas, gliomas, and acoustic neuromas (case patients) and 233 control women who were selected from the general population and frequency-matched by age to the case patients. Information on parity, menopausal status, and previous gynecologic surgeries was obtained through a standardized questionnaire. Case patients and control subjects were compared with the use of the unconditional maximum likelihood estimation of the parameters in a logistic regression model. RESULTS: Our results were not statistically significant; nevertheless, they revealed some interesting trends. No association was found between parity and the development of any of the three histological subtypes of brain tumor (relative risk [RR] = 1.31; 95% confidence interval [CI] = 0.51-2.07). Menopausal women had a greatly reduced risk of developing meningiomas (RR = 0.58; 95% CI = 0.18-1.90), and this effect was most pronounced when menopause had been surgically induced by bilateral oophorectomy (RR = 0.12; 95% CI = 0.01-1.30). Menopausal women had a greater risk of developing gliomas or acoustic neuromas (RR = 1.77; 95% CI = 0.67-4.68), except when menopause was surgically induced, in which case the risk was reduced (RR = 0.33; 95% CI = 0.04-3.09). Oophorectomy after menopause did not appear to influence risk. CONCLUSIONS: Since the onset of menopause is accompanied by cessation of estrogen production, our results support the notion that female hormones play a role in the development of brain tumors.

Contacts with animals and humans as risk factors for adult brain tumours. An international case-control study.

While numerous studies have addressed the possible role of farming and related exposures as risk factors for brain tumours in adults, few of them have examined the potential effect of exposure to farm animals or pets. In an international multicentre case-control study, we investigated whether residence on a farm, contact with animals, or working in occupations with a high degree of potential contact with animals or humans were associated with brain tumours. Using a common questionnaire, 1177 cases of glioma, 330 with meningioma and 2478 controls from eight centres were interviewed about the exposures and, in particular, about their contacts with nine species of animals: dairy cattle, beef cattle, pigs, horses, sheep, goats, poultry, dogs and cats. Living or working on a farm was not a risk factor, for either glioma or meningioma. Except in some centres, there was no relationship between having contacts with farm animals or pets and the risk of brain tumour, for either type of tumour or either sex. In relation to seven industrial groups involving frequent human and/or animal contacts, no association was apparent for either glioma or meningioma. In relation to 25 occupational groups with potential frequent contact with humans and/or animals, for glioma there was a reduced risk for biological technicians (Odds Ratio (OR)/=0, P=0.01), and general farm workers (OR=0.66, 95% Confidence Interval (CI): 0.5-0.9). For meningioma, there was an increased risk for cooks (OR=2.0; CI: 1.2-3.4). With some exceptions, these results indicate no association between either the type of brain tumour and contacts with animals, or with occupations that include a high level of contact with animals or a high level of contact with humans.

Nitrate in drinking water. A case-control study on primary brain tumours with an embedded drinking water survey in Germany.

BACKGROUND: Nitrate is known to be a precursor in the endogenous formation of N-nitroso compounds which are thought to be associated with the development of brain tumours. METHODS: We conducted a population-based case-control study on the aetiology of primary brain tumours in adults in which the nitrate concentration in drinking water was investigated as a quantitative variable. For this purpose, an additional drinking water survey was performed. RESULTS: Analysis of 173 incident cases and 418 controls did not show any relationship between exposure to nitrate in drinking water and risk of developing primary brain tumours. We found mean nitrate concentrations of 15.98 mg/l (SD 15.61) in the drinking water history of the cases and of 16.16 mg/l (SD 15.72) for controls. In addition, we compared the quantitative history of nitrate contamination of the study participants to a semi-quantitative assessment by a stick method. Although we found good agreement between these methods we would recommend the use of detailed water surveys for retrospective studies on contaminants in drinking water. CONCLUSION: The results suggest the absence of an association between nitrate levels in drinking water and the risk of brain tumours. However in order to draw definite conclusions quantitative prospective studies are needed.

Occupation, smoking and demographic factors, and renal cell carcinoma in Germany.

BACKGROUND: The role of occupational exposure in the aetiology of renal cell cancer is still not clear. In a population-based, case-control study we investigated occupational and smoking history as well as place of residence, marital and socioeconomic status. METHOD: In a case-control study in Germany, 277 adult cases with incident renal cell cancer and 286 controls frequency-matched to the cases for age and gender have been interviewed. The data were analysed by standard methods using unconditional logistic regression models, to estimate the relative risk (RR) and the corresponding 95% confidence interval (95% CI). RESULTS: Socioeconomic status was inversely associated (RR = 0.61, 95% CI: 0.3-1.2 for highest category) with the risk for renal cell cancer. Heavy smoking gave an increased, but not significant (about twofold) RR in men and women for ex-smokers and current smokers. Employment in metal-related industries (RR = 1.63, 95% CI: 1.1-2.5) was also identified as a risk factor. Additionally, we found an elevated risk associated with exposure to perchloroethylene and tetrachlorocarbonate (RR = 2.52, 95% CI: 1.2-5.2) but no time trend could be observed. No associations were found for other occupational exposures, such as working in the chemical industry, transportation or farming nor for exposure to pesticides. CONCLUSIONS: The results of our study lead to the suggestion that smoking, occupation and demographic factors probably play a minor role in the aetiology of renal cell cancer.

Traditional reviews, meta-analyses and pooled analyses in epidemiology.

BACKGROUND: The use of review articles and meta-analysis has become an important part of epidemiological research, mainly for reconciling previously conducted studies that have inconsistent results. Numerous methodologic issues particularly with respect to biases and the use of meta-analysis are still controversial. METHODS: Four methods summarizing data from epidemiological studies are described. The rationale for meta-analysis and the statistical methods used are outlined. The strengths and limitations of these methods are compared particularly with respect to their ability to investigate heterogeneity between studies and to provide quantitative risk estimation. RESULTS: Meta-analyses from published data are in general insufficient to calculate a pooled estimate since published estimates are based on heterogeneous populations, different study designs and mainly different statistical models. More reliable results can be expected if individual data are available for a pooled analysis, although some heterogeneity still remains. Large prospective planned meta-analysis of multicentre studies would be preferable to investigate small risk factors, however this type of meta-analysis is expensive and time-consuming. CONCLUSION: For a full assessment of risk factors with a high prevalence in the general population, pooling of data will become increasingly important. Future research needs to focus on the deficiencies of review methods, in particular, the errors and biases that can be produced when studies are combined that have used different designs, methods and analytic models.

An international case-control study of adult glioma and meningioma: the role of head trauma.

BACKGROUND: Increased brain tumour risk after head trauma suggested by case reports and clinical series has been previously studied epidemiologically with mixed results. An international multicentre case-control study investigated the role of head trauma from injury or sports participation in adult brain tumour risk. METHODS: In all, 1178 glioma and 330 meningioma cases were individually or frequency matched to 2236 controls. Only exposures that occurred at least 5 years before diagnosis and head injuries that received medical attention were considered. RESULTS: Risk for ever having experienced a head injury was highest for male meningiomas (odds ratio [OR] = 1.5, 95% confidence interval [CI] : 0.9-2.6) but was lower for 'serious' injuries, i.e. those causing loss of consciousness, loss of memory or hospitalization (OR = 1.2, 95% CI: 0.6-2.3). Among male meningiomas, latency of 15 to 24 years significantly increased risk (OR = 5.4, 95% CI: 1.7-16.6), and risk was elevated among those who participated in sports most correlated with head injury (OR = 1.9, 95% CI: 0.7-5.3). Odds ratios were lower for male gliomas (OR = 1.2, 95% CI : 0.9-1.5 for any injury; OR = 1.1, 95% CI: 0.7-1.6 for serious injuries) and in females in general. CONCLUSIONS: Evidence for elevated brain tumour risk after head trauma was strongest for meningiomas in men. Findings related to sports should be interpreted cautiously due to cultural variability in our data and our lack of complete data on physical exercise in general which appeared to be protective.

[Limitations of meta-analysis from published data in epidemiological research]. / Grenzen von Metaanalysen aus publizierten Daten bei epidemiologischen Fragestellungen.

Metaanalyses of epidemiological studies have increased during the last years and are often used to evaluate the effect of risk factors which are inconsistent in different studies, mainly for small risk factors. Very often a metaanalysis is performed from published data. In this article we discuss this form of a metaanalysis and investigate whether the requirement to get reliable information is achievable with it. We mainly ask questions whether qualitative and quantitative dose-response analysis can be performed. We point out the differences between metaanalysis from experimental data and clinical randomized studies and epidemiological studies. We discuss different arguments that were given for performing metaanalysis in clinical trials and investigate whether they are also valid in observational studies. We mainly concentrate on the problem of estimating a single pooled risk estimate. Two examples from literature are used to show problems with metaanalysis from published data.

[Is there an increased risk of leukemia, brain tumors or breast cancer after exposure to high-frequency radiation? Review of methods and results of epidemiologic studies]. / Gibt es ein erhöhtes Risiko für Leukämien, Hirntumoren oder Brustkrebs nach Exposition gegenüber Hochfrequenzstrahlung?

BACKGROUND: There are only a few epidemiologic studies investigating risk factors in persons occupationally exposed to high-frequency radiation (e.g. radio-, TV-waves, mobile phones or microwaves). The results of the studies are mostly inconsistent. METHODS: All epidemiologic studies which investigated the association between occupational exposure to high-frequency radiation and the risk of leukemia, brain tumors or breast cancer were included in this review. All studies published between 1980 and 1997, such as record-linkage, case-control, and cohort studies, were retrieved from MEDLINE. Incidence and mortality studies are included. Methodologic problems of these investigations are discussed. RESULTS: Most of the recent epidemiologic studies do not present quantitative exposure data or data on the specific frequencies of electro magnetic fields. In general, the relative risks for leukemia, brain tumors or breast cancer are small, not significant and inconsistent. Confounder variables were not included in most of the analyses and no dose-response relationship was reported. CONCLUSION: To increase the power and the validity of the studies a re-analysis based on original data of all previous studies in this field is recommended. Additionally, to investigate the influence of high-frequency radiation on the development of cancer, international epidemiologic studies are necessary. Only they would have sufficient sample size to detect small elevated risks.

Occupation and risk of glioma, meningioma and acoustic neuroma: results from a German case-control study (interphone study group, Germany).

BACKGROUND: Several epidemiological studies have investigated the association between occupation and brain tumour risk, but results have been inconclusive. We investigated the association between six occupational categories defined a priori: chemical, metal, agricultural, construction, electrical/electronic and transport, and the risk of glioma, meningioma and acoustic neuroma. METHODS: In a population-based case-control study involving a total of 844 cases and 1688 controls conducted from 2000 to 2003, detailed information on life-long job histories was collected during personal interviews and used to create job calendars for each participant. Job title, job activity, job number, and the starting and ending dates of the activity were recorded for all activities with duration of at least 1 year. Reported occupational activities were coded according to the International Standard Classification of Occupations 1988 (ISCO 88). For the analyses we focused on six a priori defined occupational sectors, namely chemical, metal, agricultural, construction, electrical/electronic and transport. Multiple conditional logistic regression analysis was used to estimate odds ratios and their 95% confidence intervals. RESULTS: Most of the observed odds ratios were close to 1.0 for ever having worked in the six occupational sectors and risk of glioma, meningioma and acoustic neuroma. Sub-group analyses according to duration of employment resulted in two elevated odds ratios with confidence intervals excluding unity. CONCLUSIONS: We did not observe an increased risk of glioma or meningioma for occupations in the agricultural, construction, transport, chemical, electrical/electronic and metal sectors. The number of 'significant' odds ratios is consistent with an overall 'null-effect'.

Lack of association of herpesviruses with brain tumors.

Gliomas are the most frequent primary brain tumors in humans. Many studies have been carried out on their etiology; however, the only confirmed risk factors are hereditary predisposing conditions and high dose of ionizing radiation. Recently, human cytomegalovirus (HCMV) gene products and nucleic acids were reported to be present in all of 27 glioma samples investigated in contrast to other brain tissues, and it was hypothesized that HCMV might play a role in glioma pathogenesis. To evaluate these findings, samples of 40 gliomas, 31 meningiomas, and 6 acoustic neurinomas (ACNs) were analyzed for the presence of HCMV macromolecules using polymerase chain reaction (PCR) and immunohistochemistry. Additionally, corresponding blood samples from 72 patients were analyzed for the presence of HCMV DNA to check for a possible contamination of tumor tissues with HCMV-infected blood cells. No HCMV DNA sequences were found, neither in brain tumor tissues nor in corresponding blood samples. Immunohistochemistry did not detect HCMV-specific proteins. Addressing a possible role of other herpesviruses as has been suggested in seroepidemiological studies, seroprevalence of antibodies to HCMV, herpes simplex virus (HSV), Epstein-Barr virus (EBV), and varicella-zoster virus (VZV) were determined by enzyme-linked immunosorbent assay (ELISA). Serological analyses of brain tumor patients showed no significant differences in the prevalences of antibodies to HCMV, HSV, EBV, or VZV compared to the general population. Thus, the data of the present study do not support the hypothesis of an association of herpesviruses with the development of primary brain tumors.

Diet, obesity and risk for renal cell carcinoma: results from a case control-study in Germany.

Increasing incidence of renal cell carcinoma in Western countries raises particular attention to its etiology. Diet may be related to risk for renal cell carcinoma since obesity has been linked with this malignant condition. A case-control study with 277 incident renal cell cancer patients (ICD 189.0) and 286 population controls was conducted in the Rhein-Neckar-Odenwald area, Germany, in the period of 1989 to 1991. The core study protocol included a face-to-face interview about demographical parameters, previous diseases, medication, tobacco smoking, occupational history, occupational exposures, beverage consumption, and obesity. In addition, study participants were asked to fill in a self-administered food frequency questionnaire with 122 food items to estimate overall food intake. Fifty-six % of the cases and 74% of the controls participated in this part of the study (n = 155 cases and 212 controls). This was 47% of the original cases (n = 328) and 56% of the controls (n = 381). No selection bias could be identified with regard to age group, gender, educational status or recent BMI in the analyzed group compared with the eligible cases and controls. Relative risk (RR) estimates for tertiles of consumption revealed a significantly increased risk with increasing intake of fat spread (RR of high intake compared to low intake: 1.90 (95% CI 1.08-3.32)). Increased risk was also found for intake of meat and meat products (RR of high intake compared to low intake: 1.71 (95% CI 0.96-3.04)) and energy adjusted fat (RR of high intake compared to low intake: 1.64 (95% CI 0.95-2.83)). A decreased risk was seen with increasing intake of fruit (RR of high intake compared to low intake: 0.40 (95% CI 0.23-0.69)) and of vitamin C (RR of high intake compared to low intake: 0.62 (95% CI 0.37-1.05)). Beverage consumption, preparation of food and eating pattern were not linked with risk of renal cell cancer. The relative risk estimates of spreading fat (sauce and vitamin C intake were tested in two models, with and without including BMI as covariate. In both models significant associations of these nutritional variables with risk for renal cell cancer remained. The current results indicate that specific food pattern associated with obesity explain differences in incidence of renal cell carcinoma in industrialized countries.

Dietary carcinogens and the risk for glioma and meningioma in Germany.

A population-based case-control study was performed in South-West Germany in 1987/88 with 115 histological confirmed glioma and 81 meningioma cases and 418 randomly selected controls. On the basis of information from a food-frequency questionnaire and questions on food preparation and food supply, the role of dietary carcinogens, in particular N-nitroso compounds or their precursors, on risk for glioma and meningioma were analyzed by multiple logistic regression. Eleven food groups were investigated. The intake of processed meat was significantly associated with an increased risk of glioma. The intake of any food group was not significantly related to meningioma risk. Among single meat products, a significantly higher risk of glioma was found for cooked ham, processed pork meat and fried bacon. For the consumption of 3 N-nitrosamines, assessed from the intake of processed meat and cheese, significant positive relations to glioma risk were found. These N-nitrosamines were also related to meningioma risk, although to a less pronounced extent. The risk for occurrence of glioma was significantly increased for those using vegetable fat frequently for deep frying, as compared with non-users. For the dietary intake of nitrate, nitrite, vitamin C, specific alcoholic beverages, total alcohol, and water from a non-central supply, no elevated risk was found in this study.

Medical risk factors and the development of brain tumors.

Several diseases and medical treatments are discussed as risk factors for the development of brain tumors. A population-based case-control study in the Rhein-Neckar-Odenwald area (containing 1.3 million inhabitants) of Germany was established to investigate this question. A total of 226 patients (cases) with primary brain tumors (International Classification of Diseases, ninth edition, classes 191, 191.1, and 192.0) and 418 control subjects (controls) were interviewed using a standardized questionnaire over a period of 2 years. No association was seen for head injuries, hereditary diseases, family history, and radiographic examination of the head and teeth. However, more cases than controls had had meningitis (relative risk [RR], 2.7; 95% confidence interval [CI], 0.9 to 8.6) or epilepsy (RR, 2.6; 95% CI, 0.6 to 11.7). The RR was decreased for those who had allergic diseases (RR, 0.7; 95% CI, 0.5 to 1.0), diabetes (RR, 0.7; 95% CI, 0.3 to 1.8), and infections and colds (RR, 0.3; 95% CI, 0.1 to 0.8).

Occupational risk factors for brain tumors: results from a population-based case-control study in Germany.

In a population-based case-control study in the Rhein-Neckar-Odenwald area (containing 1.3 million inhabitants) of the Federal Republic of Germany (FRG), risk factors were assessed for brain tumor development in 226 cases with primary brain tumors (ICD-9 191, 192.1, 192.0) and 418 population controls, interviewed by a standardized questionnaire. The analysis of occupational risk factors and smoking is presented. No elevated risk was found for smoking. Similarly, no significant effects were found for most occupations. Five specific occupational groups were examined because of a priori determination that they were of interest. Some categories showed slightly elevated risks but in none was the elevation statistically significant. A significant increase in risk for brain tumor development was found associated with working in electrical occupations for women (relative risk [RR] = 5.2; 95 percent confidence interval [CI] 1.4-20.1) but not for men (RR = 0.9, 95 percent CI 0.3-2.3).