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May 2009

No clear association was observed between mobile phone use and adult leukemia in Thailand.

The aim of this case-control study conducted in Bangkok, Thailand, was to evaluate potential contribution of mobile phone use and other factors to the etiology of adult-onset leukemia. No clear association was observed with mobile phone use, but durations of use were relatively short (median 24-26 months). There was a suggestion of an increase in risk in relation with certain usage practices and with the use of GSM service. The authors observed associations between leukemia and a number of other factors: exposure to benzene, solvents, occupational pesticides and working with or near power lines. With regard to mobile phone use, they conclude that its relation with the disease remains unclear.

Kaufman DW, Anderson TE, Issaragrisil S. Risk factors for leukemia in Thailand. Ann Hematol. 2009 Mar 18 Ahead of print

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A meta-analysis of epidemiological studies suggests a link between long-term cell phone use and the risk of ipsilateral brain tumours

In order to address the question of whether or not there is evidence for an association between long-term (10 years or more) cell phone use and the risk of brain tumours, the authors conducted a meta-analysis of relevant epidemiological studies published in peer reviewed journals. The results of the meta-analysis which includes 11 long-term epidemiologic studies indicate that using a cell phone for 10 years or more approximately doubles the risk of brain tumours on the side of the head where the cell phone is used (ipsilateral tumours). The authors conclude that there is sufficient epidemiologic evidence to suggest a link between long-term cell phone use and the development of ipsilateral brain tumours.

Khurana VG, Teo C, Kundi M, Hardell L, and Carlberg M. Cell phones and brain tumors: a review including the long-term epidemiologic data. Surg Neurol. 2009 Mar 26 Ahead of print.

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Similar mechanisms are possibly involved in the pathophysiology of tinnitus and electromagnetic hypersensitivity.

Tinnitus, the perception of sound in the absence of an external sound, is a frequent and difficult to treat condition with incompletely understood pathophysiology. The term “subjective electromagnetic sensitivity” describes individuals suffering from a variety of subjective symptoms and attributing these symptoms to EMF exposure. The study was aimed at evaluating the relationship between EMF exposure, electromagnetic hypersensitivity and tinnitus using a case-control design. The frequency of tinnitus was higher in the electromagnetic hypersensitive group, whereas tinnitus duration and severity did not differ from the control. No association was found between tinnitus and measures of individual EMF exposure. The authors have concluded that tinnitus is associated with subjective electromagnetic hypersensitivity but not with EMF exposure; similar mechanisms are, possibly, involved in the pathogenesis of these two conditions. Hence, therapeutic strategies successful in electromagnetic hypersensitivity can be applied for treatment of tinnitus.

Landgrebe M, Frick U, Hauser S, Hajak G, Langguth B. (2009). Association of tinnitus and electromagnetic hypersensitivity: hints for a shared pathophysiology? PLoS ONE. 4(3):e5026.

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Wireless telephones and the blood-cerebrospinal fluid barrier

Dysfunction of the blood-brain barrier in relation to radiofrequency electromagnetic field exposure has long been debated. Much less attention has been paid to the blood-cerebrospinal fluid barrier (BCSFB). Transthyretin (TTR), a key protein of cerebrospinal fluid, can potentially serve as a marker of BCSFB dysfunction. The objective of this study was to test whether the use of wireless (mobile and cordless) telephones was associated with changes in the serum TTR concentrations as a marker of alterations in TTR concentrations in the cerebrospinal fluid. One thousand subjects (500 male and 500 female) aged 18-65 years randomly selected from a population registry were invited to participate in the study, and 314 participated by answering a postal questionnaire and giving blood. Significant increase was observed in TTR levels with increasing time since first use of wireless phones, regardless of the intensity of use. With respect to short term use, the sooner the blood was drawn after the most recent telephone call, the higher TTR concentrations were seen in serum of female participants.

Soderqvist F, Carlberg M, Hardell L. Mobile and cordless telephones, serum transthyretin and the blood-cerebrospinal fluid barrier: a cross-sectional study. Environ Health. 2009 Apr 21 Ahead of print 8(1):19.

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SAR characterization inside intracranial tumours

Evaluation of exposure to radiofrequency radiation has always been a concern in epidemiological studies of mobile phone use and cancer. The purpose of this study was to introduce a dose metric in the exposure assessment taking into account spatial distribution of exposure. Based on SAR distributions and technical specifications, mobile phones were classified into four categories. SAR distributions estimated inside 275 cases of brain tumours were shown to be dependent on phone categories. Epidemiologists usually categorize contralateral tumours as non-exposed, and the study results confirm this categorization: the maximum SAR in the contralateral tumour was less than 2.5% of the maximum SAR in the brain. The maximum SAR in 75% of the ipsilateral tumours was less than 15% of the maximum SAR in the brain and far below the International Commission on Non-Ionizing Radiation Protection (ICNIRP) safety limits concerning localized SAR. Three new exposure indices were created for use in epidemiological studies.

Varsier N , Wake K, Taki M, Watanabe S, Takebayashi T, Yamaguchi N, Kikuchi Y. (2008): SAR characterization inside intracranial tumors for case–control epidemiological studies on cellular phones and RF exposure. Annals of Telecommunications. 63(1-2):65-78.

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Comparison of SAR induced in homogeneous and heterogeneous biological structures.

Methods and protocols to check for compliance with international exposure limits have been studied and standardized for a mobile phone handset close to the head. With the recent increase in the use of a hands-free kit, the mobile phone is increasingly used in a body-worn position. Therefore, new methods are required for compliance checks. The aims of this study were 1) to verify if the equivalent head liquid, designed for testing the handsets close to the head, can represent heterogeneous tissues of the trunk and 2) to calculate a correction factor that should be applied when using the equivalent head liquid to represent heterogeneous tissues. The SAR was evaluated in multilayer structures with different thicknesses and the results were compared to those obtained in the homogeneous equivalent head liquid. In both cases, the source was a half-wavelength dipole placed at different distances from those structures and operating at frequencies between 300 MHz and 6 GHz. It has been shown that the thickness of subcutaneous fat influences SAR calculations; the correction factor depends on the distance between the dipole and the multilayer structure, the composition of the structure, and the coupling between the source and the structure.

Pradier A , Hadjem A, Lautru D, Gati A, Wong MF, Hanna VF, Wiart J. (2008): Evaluation of the SAR induced in a multilayer biological structure and comparison with SAR in homogeneous tissues. Annals of Telecommunications. 63(1-2):79-86.

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Reference levels provide a conservative estimation of compliance with the whole-body SAR but not localized SAR.

Guidelines for limiting electromagnetic field exposure set by International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Institute of Electrical and Electronics Engineers (IEEE) are based on basic restrictions defined in terms of Specific Absorption Rate (SAR). Since SAR cannot be directly measured, reference levels of exposure are used for comparison with measured values of incident fields (e.g. power density) and for determining whether or not the basic restrictions are met. The goal of this numerical dosimetry study of a typical UMTS base-station antenna was to analyze the relationship between the antenna input powers required to reach the SAR limit and those required to reach the power density limit. The second goal was to underline the key points that impact the local SAR. Two numerical approaches were used. The results of this study confirm that the reference levels provide a conservative estimation of compliance with the whole-body SAR regardless of the position of the antenna or methods used for averaging the values. However, the results indicate that compliance of the averaged power density to the reference levels is not sufficient to ensure compliance to localized SAR.

Lacroux F, Conil E, Carrasco AC, Gati A, Wong MF, Wiart J. (2008): Specific absorption rate assessment near a base-station antenna (2,140 MHz): some key points. Annals of Telecommunications. 63(1-2):55-64.

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Assessment of validity and accuracy of spatial averaging of electromagnetic fields

The Institute of Electrical and Electronic Engineers (IEEE) and International Commission on Non-Ionizing Radiation Protection (ICNIRP) provide electromagnetic field reference levels to protect against adverse effects of electromagnetic radiation. For comparison with these reference levels, IEEE and ICNIRP recommend a mean value of the field obtained by spatial averaging the squares of the field strength over the height of the body. However, when an antenna is close to the body, the field varies significantly depending on the location at which it is measured. The aim of the study was to assess the validity and accuracy of spatial averaging. Spatially averaged fields were calculated using different numbers of points over the height of a human body model. The results suggest that the use of modern equipment which takes hundreds rather than tens of measurements is preferable in order to obtain a sufficiently accurate mean field value. Calculations of whole-body averaged and peak localized SAR values, normalized to spatially averaged fields, have shown that the reference levels were conservative for all whole-body SAR values, but not for localized SAR. However, if the maximum field was used for normalization as opposed to the lower spatially averaged value, the reference levels provided a conservative estimate of the localized SAR basic restriction.

Findlay RP, Dimbylow PJ. Spatial averaging of fields from half-wave dipole antennas and corresponding SAR calculations in the NORMAN human voxel model between 65 MHz and 2 GHz. Phys Med Biol. 2009 Apr 21; 54(8):2437-47.

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Methods for estimation of long-term exposures to FM, GSM, and UMTS based on short-period measurement results.

The purpose of this study was to investigate how short-period measurements can be related to the actual maximum and average exposure of the general public during longer periods of time, such as 1 week. The authors propose methodologies for extrapolation of short-period measurements (30 minutes or less instead of one or more days). Measurements of exposure to FM, GSM, and UMTS were made during a week at 5 different sites. A factor X was introduced and defined as the ratio of the actual maximum field value to the maximum field value estimated from short-period measurements. Three different methods to assess X were compared and an optimal method was proposed for an in-situ measurement procedure. A factor R was defined as the ratio between the median and maximum values of the short-period field measurements, which allows converting maximum values to median values and vice versa. Combination of factors X and R enables one to estimate the actual maximum and median exposure during longer periods from short-period measurements.

Joseph W, Verloock L, Tanghe E, Martens L. In-situ measurement procedures for temporal RF electromagnetic field exposure of the general public. Health Phys. 2009 May; 96(5):529-42.

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SAR changes in a human head model for plane wave exposure (500 - 2500 MHz) and a comparison with safety limits

This paper compares external electric field values form the largest peak average 10 g SAR in a plausible human head model with the Institute of Electrical and Electronic Engineers (IEEE) and International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference levels. The model head is exposed to 7 different frequencies ranging from 500 MHz to 2500 MHz. The study results indicate that metallic wire spectacles will lower the external electric field levels in the region above 900 MHz. The authors concluded that their comparison of electric field values shows that the established IEEE and ICNIRP safety limits provide a conservative estimate.

Yelkenci T, Paker S. (2008): SAR changes in a human head model for plane wave exposure (500 - 2500 MHz) and a comparison with IEEE 2005 safety limits. J Microw Power Electromagn Energy. 42(2):64-68.

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Does radiofrequency radiation affect the cochlear functions?

The objective of this study is to determine the effects of 1800 MHz GSM-like radiofrequency (RF) radiation on the cochlear functions of pregnant adult rabbits by Distortion Product Otoacoustic Emissions (DPOAEs). The radiation caused decreases in DPOAE amplitudes mainly in non-pregnant adult rabbits. Prolonged exposure may affect the DPOAE amplitude. Recommendations are given to prevent the potential hazardous effects of RF in humans.

Budak GG, Muluk NB, Ozturk GG; Budak B; Apan A, Seyhan N, Sanli C. (2009). Effects of GSM-like radiofrequency on distortion product otoacoustic emissions in pregnant adult rabbits. Clin Invest Med. 32(2):E112-6.

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Cellular effects of radiofrequency (RF) radiation from mobile phones

 The aim of study is to determine the influence of mobile phone RF radiation on the proliferation, cytoskeleton structure, and mitotic index of V79 cells after various periods of exposure. Although exposure did not affect the number of dividing cells, it may have slowed down cell division kinetics as a consequence of microtubule impairment immediately after exposure.

Trosić I, Pavicić I. (2009). Disturbance of cell proliferation in response to mobile phone frequency radiation. Arh Hig Rada Toksikol. 60(1):109-15.

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Effects of mobile phone radiofrequency field (RF) exposure on spatial memory performance 

The objective of this study is to test the effects of mobile phone radiofrequency field exposure on spatial memory performance. It is concluded that mobile phone RF exposure affected the acquisition of learned responses in Wistar rats.

Narayanan SN, Kumar RS, Potu BK, Nayak S, Mailankot M. (2009). Spatial memory performance of Wistar rats exposed to mobile phone. Clinics. 64(3):231-4.

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No stress response after exposure to radiofrequency fields in fetal mouse brain

The objective of this study is to determine whether whole of gestation exposure of fetal mouse brain to mobile telephone RF fields produces a stress response detectable by induction of heat shock proteins (HSPs). Whole of gestation exposure of fetal mouse brains to mobile phone RF fields did not produce any stress response using HSPs as an immunohistochemical marker.

Finnie  JW, Chidlow G, Blumbergs PC, Manavis J, Cai Z. (2009). Heat shock protein induction in fetal mouse brain as a measure of stress after whole of gestation exposure to mobile telephony radiofrequency fields. Pathology. 41(3):276-9.

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Effects of radiofrequency field (RF) radiation from mobile phones on blood-brain barrier permeability

This study investigates the effects of GSM mobile phone RF radiation upon the blood-brain barrier (BBB) permeability of rats. The investigators found an increased BBB permeability immediately and 14 days after exposure to RF fields.

Nittby H, Brun A, Eberhardt J, Malmgren L, Persson BR, Salford LG. Increased blood-brain barrier permeability in mammalian brain 7 days after exposure to the radiation from a GSM-900 mobile phone. Pathophysiology. 2009 Apr 1 Ahead of print.

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Absence of genotoxic effect in mice of radiofrequency field radiation from wireless signals

The aim of the present investigation was to determine the incidence of micronuclei in peripheral blood erythrocytes of B6C3F1 mice that had been chronically exposed to RF used for mobile communication. The data did not indicate RF-induced genotoxicity in mice after two years of exposure.

Ziemann C, Brockmeyer H, Reddy SB, Prihoda TJ, Kuster N, Tillmann T, Dasenbrock C. Absence of genotoxic potential of 902 MHz (GSM) and 1747 MHz (DCS) wireless communication signals: In vivo two-year bioassay in B6C3F1 mice. Int J Radiat Biol. 2009 Apr Ahead of print. 8:1-11.

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Standardized questionnaires and access to industry data are essential for increasing the capacity of epidemiological studies to evaluate the potential association between acoustic neuroma and cell phone use.

The authors have reviewed current epidemiologic studies (10 case-control studies, 1 cohort study and 1 meta-analysis) of cell phone use and acoustic neuroma in order to identify their limitations and to provide suggestions for future studies. While most studies did not find any association between the development of acoustic neuroma and cell phone use, some studies with follow-up of 10 years or more detected such an association. Limitations include difficulties in evaluation of other potential risk factors for acoustic neuroma and limited ability to assess cell phone exposure in retrospective studies. Acquiring data on cell phone use prospectively, obtaining retrospective billing records for validation of exposures, and incorporating information from detailed questionnaires on other potential risk factors for acoustic neuroma could considerably increase the capacity of studies to evaluate whether or not cell phone use is associated with acoustic neuroma.

Han YY, Kano H, Davis DL, Niranjan A, Lunsford LD. Cell phone use and acoustic neuroma: the need for standardized questionnaires and access to industry data. Surg Neurol. 2009 Mar 26 Ahead of print.

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Research does not provide consistent evidence of an association between mobile phone use and head and neck tumours.
Literature on potential health risks of mobile phone use, in particular the risk of developing head and neck tumours, is heterogeneous. The authors have made an attempt to consolidate various reports on the results of epidemiological studies of mobile phones and mobile phone-related technologies, and head and neck tumours. The authors believe that, although associations between mobile phone use and tumours have been reported in some individual studies, this research does not provide consistent evidence of such an association. Reported small associations between mobile phone use ipsilateral to the tumour for longer than 10 years are especially prone to confounding by recall bias. These associations can be treated as more than suggestive only after they are replicated using methods designed to minimize such bias.

Croft RJ, McKenzie RJ, Inyang I, Benke GP, Anderson V, Abramson MJ. (2008). Mobile phones and brain tumours: a review of epidemiological research. Australas Phys Eng Sci Med. 31(4):255-67.

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Different conclusions are reached in the two sets of recent case-control studies.

The author has reviewed all case-control studies on the risk of brain tumours from cell phone use published up to March 2009. The author focuses on more recent studies with longer exposure duration, the INTERPHONE studies and the Swedish studies, which have reached different conclusions. While the industry-funded INTERPHONE studies (with four exceptions) found no association between the risk of brain tumours and cell phone use, the independently funded Swedish studies reported numerous findings of significant increase in brain tumour risk related to cell phone and cordless phone use. Having analyzed the data from the INTERPHONE studies, the author suggests two possible explanations for their findings: either the use of a cell phone protects from a brain tumour, or (more likely) the studies had serious design flaws. Eleven flaws were identified, eight of which could lead to underestimation of the risk. In contrast to the INTERPHONE studies results, which, in the author’s view seem to be incredulous, the Swedish studies are internally consistent if cell phone and cordless phone use is a risk factor for brain tumours. However, some of the identified design flaws are also pertinent to the Swedish studies. The author concludes if the risk exists, public health impact will be enormous. Application of the precautionary principle is, therefore, justified.

Morgan LL. Estimating the risk of brain tumors from cellphone use: Published case-control studies. Pathophysiology. 2009 Apr 6 Ahead or print.

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Precaution is recommended in cell phone use

In a Letter to the Editor, the authors express and substantiate the view that precautionary approach should be applied to cell phone use. They recommend simple precautionary steps to limit the exposure to radiation from cell phones.

Khurana VG; Teo C, Bittar R.G. Health risks of cell phone technology. Surg Neurol. 2009 Mar 27 Ahead or print.

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Caution, further research and regulatory changes are needed.

The author agrees with Khurana et al., 2009 that caution is required with regard to cell phone use and expresses hope for appropriate further research and regulatory changes.
Pawl R. Commentary. Surg Neurol. 2009 Mar 27.

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