avril 2008

Hormones relevant to endocrine functions do not appear under experimental conditions to be persistently affected following exposure to cellular phone use in men.

The objective of the current investigation was to measure the variation in hormonal levels such as steroid and pituitary hormones in healthy male volunteers exposed to radiofrequency radiation from cellular phone use. Each participant used a cellular phone for 2 hours/day, 5 days/week, for duration of 4 weeks and had blood samples collected each hour at night and each 3 hours during the day period. The blood measurements included; maximum serum concentration and time of the peak which were both performed 4 times: before the experiment, at the middle and at the end of the exposure from cellular phones and 15 days post-exposure. All serum hormonal measurements were all within the normal physiological range. Results indicate prolactin, thyroid-stimulating hormone, adrenocorticotropin and testosterone were not affected by RF exposure but growth hormone and cortisol were significantly decreased only during the exposure period but not post-exposure.

Djeridane Y, Touitou Y, de Seze R. (2008). Influence of Electromagnetic Fields Emitted by GSM-900 Cellular Telephones on the Circadian Patterns of Gonadal, Adrenal and Pituitary Hormones in Men. Radiat. Res. 169:337-343.

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Australian case-control study finds no evidence of any association from occupational radiofrequency exposure and risk of glioma (brain tumour) in adults.

The present case-control study investigated occupational risk factors such as exposure to radiofrequency fields (RF) and the risk of glioma. Occupational exposure of 416 cases of glioma and 422 controls was assessed using a detailed occupational history (Finnish job exposure matrix; FINJEM) for all types of radiation. Results showed consistent odds ratio below unity for RF as well as the other types of radiation exposure. The authors concluded that the study did not find any association between RF and brain tumour type glioma.

Karipidis KK, Benke G, Sim MR, Kauppinen T, Giles G. (2007). Occupational exposure to ionizing and non-ionizing radiation and risk of glioma Occupational Medicine 57(7):518-524; Ahead of print 29 August 2007doi:10.1093/occmed/kqm078

For more see “Research – epidemiological – other studies – other occupations”
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Hocking questions the study methodology including the Finnish job exposure matrix used for the Australian context in Karipidis’ study.

Hocking B. (2008). Letter to the Editor: Occupational exposure to ionizing and non-ionizing radiation and risk of glioma Occupational Medicine 58(2):148-149; doi:10.1093/occmed/kqm143.

For more see “Research – epidemiological – other studies – other occupations”

Reply to Ha et al on study of radiofrequency fields and childhood leukemia and brain cancer.

Schüz and colleagues comment on the Korean study of Ha et al. Although they indicate the research is of better quality than previous studies of radiofrequency exposure from television and radio broadcast transmitters, they are however concerned about some possible methodological errors; they request clarification on some issues including (1) further justification of the distance approach methodological analysis; (2) the decision to use quartiles would probably reduce the likelihood of finding a possible effect; and (3) an explanation on how the calculation were done is warranted especially as the units for the distance and the field in the applied corrections are not available.

Schüz J, Philipp J, Merzenich H, Schmiedel S, Brüggemeyer H. Re: "Radio-frequency radiation exposure from AM radio transmitters and childhood leukemia and brain cancer” American Journal of Epidemiology Ahead of print February 28, 2008 doi:10.1093/aje/kwn014.

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Ha and colleagues respond to Schüz.

The authors note an error occurred in Table 2 and the corrected estimates show a higher risk for lymphocytic leukemia for peak radiofrequency radiation. Answers are presented to the concerns by Schüz and an explanation on the calculations and which units were used are also presented.

Ha M, Im H, Kim BC, Gimm YM, Pack JK. Letter to Editor.  American Journal of Epidemiology. Ahead of print February 28, 2008. doi:10.1093/aje/kwn013.

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Development of whole-body exposure system for cellular and PCS frequency in a reverberation chamber.

The authors developed a whole-body exposure system using a reverberation chamber and validated their approach with simulations and measurements. Specific absorption rate (SAR) inside mice was calculated via the simulations. The field uniformities in the exposure chamber were tested both by simulation and measurement. Results indicate field uniformity in the test region is excellent as the standard deviation is close to 2 dB. SAR values calculated for the measured field distribution provide evidence the maximum 1g-averaged SAR values are reasonably high thus suitable for any animal experiments. Key results of the experiment are presented in the full paper.

Jung KB, Kim TH, Kim JL, Doh HJ, Chung YC, Choi JH, Pack JK. (2008). Development and Validation of Reverberation-Chamber Type Whole-Body Exposure System for Mobile-Phone Frequency. Electromagnetic Biology and Medicine 27(1):73-82.

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Magnetic flux density spectrum is required for accurate exposure evaluation from mobile phones.

The present study compared two methods (magnetic flux density vs frequency spectrum of the supply current) to estimate the exposure of magnetic field in the range 217 Hz to 2.4 kHz from mobile phones, electric drill, hair dryer, and fluorescent desk lamp. Results show that the two measurement methods are different. The frequency of the supply current method lead to an overestimation of the magnetic field exposure by a factor of 2.2 for the mobile phone but an underestimation by a factor of 2.3 for the other three electrical appliances. The authors concluded it is better to use the magnetic flux density spectrum to achieve accurate exposure assessment.

Straume A, Johnsson A, Oftedal G, Wilen J. (2007). Frequency spectra from current vs magnetic flux density measurements for mobile phones and other electrical appliances. Health Physics 93(4):279-287.

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Methodology used to assess exposure from high-voltage power lines in case-control studies in the UK.

Swanson describes the methodology used to determine the exposure from magnetic fields produced by power lines in two UK epidemiological studies of cancer in children and adults. The methods consist of using grid references for participants’ address and pylons’ location in order to determine the exact distance the subjects live from the power line pylons. All calculations of magnetic fields exposure from power lines were done by predicting the loads. This method could potentially lead to errors in the calculations. It was possible to compare, only for the recent year, the predicted loads used in the studies with the actual loads to evaluate the validity of the data. Steps that were taken to make these calculations are fully described in the paper. The author notes an important limitation; the accuracy of the calculated fields is the predictions of loads. It was concluded the prediction of loads introduces a significant misclassification but that using these predicted loads is superior than not using any loads in the analyses.

Swanson J. (2008). Methods used to calculate exposures in two epidemiological studies of power lines in the UK.  J Radiol Prot 28:45-59.  

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Non-significant increase in frequency of micronucleated exfoliated cells (in buccal-mucosa) in subjects using mobile phones.

The research of Yadav et al was designed to detect whether mobile phone radiofrequency could cause any in vivo outcome on the frequency of micronucleated exfoliated cells (in buccal-mucosa). The exposed subjects were 85 regular mobile phone users and the control group was composed of 24 non-users sex–age-matched. One thousand exfoliated cells were tested from each individual for any effect such as micronuclei (MN), karyolysis (KL), karyorrhexis (KH), broken egg (BE) and binucleated (BN) cells. Results confirm a small non-statistically significant increase in mean frequency of KH, BE and BN in the RF-exposed individuals. However, the authors state an important finding of their study is the positive correlation between 0–1, 1–2, 2–3 and 3–4 years of exposure and the frequency of micronucleated cells (MN) and total micronuclei (TMN) but a small decrease for mobile phone users exposed more than 4 years.

Yadav AS, Sharma MK. (2008). Increased frequency of micronucleated exfoliated cells among humans exposed in vivo to mobile telephone radiations. Mutation Research/Genetic Toxicology and Environmental Mutagenesis 650(2):175-180.

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No evidence that non-thermal radiofrequency field (RF) exposure could affect gene expression in human cells when compared to control groups.

This important investigation is an attempt to confirm previous laboratory work that shows no effect of 1.9 GHz pulse-modulated RF fields on the gene expression of human glioblastoma. This study looks at genes in U87MG cells after an RF exposure period of 24-hour in addition to a human monocyte-derived cell-line (Mono-Mac-6, MM6) after a 6-hour exposure period of 5 min ON; 10 min OFF. Once more, this study provides no evidence that non-thermal RF exposure would affect gene expression for U87MG or MM6 cells when compared to control groups. The authors do mention however, that cells exposure to heat-shock conditions (43 degrees C for 1 h) did alter the expression of some heat-shock proteins.

Chauhan V, Qutob SS, Lui S, Mariampillai A, Bellier PV, Yauk CL, Douglas GR, Williams A, McNamee JP. (2007a). Analysis of gene expression in two human-derived cell lines exposed in vitro to a 1.9 GHz pulse-modulated radiofrequency field. Proteomics 7(21):3896-3905.

For more see “Research – laboratory – cancer studies”
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High EMF exposure (SAR; 4.0 W/Kg) triggered stress response and diminished viability but not lower exposure limit (1.6 W/Kg) in flies Drosophila model.

This research assessed the biological effects of mobile phone exposure from 835 MHz electromagnetic field (EMF) in flies Drosophila model. Ninety percent of flies exposed to the SAR limit guidelines established in America (1.6 W/Kg) were still viable after 30 hours of EMF exposure. However, SAR level of 4.0 W/Kg for 12 hours of exposure diminished the viability and produced stress response, increased reactive oxygen species, activated extracellular signal regulated kinase (ERK) and terminal kinase. SAR 1.6 W/Kg did activate the ERK and the expression of the anti-apoptotic gene. Both SAR levels activate ERK survival signaling but the elevated SAR also activated the terminal kinase signal in flies.

Lee KS, Choi JS, Hong SY , Son TH, Yu K. Mobile phone electromagnetic radiation activates MAPK signaling and regulates viability in Drosophila. Bioelectromagnetics Ahead of print 19 February 2008 10.1002/bem.20395.

For more see “Research – laboratory – other – cell death (apoptosis)”
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900 MHz radiofrequency exposure of pigs head to three different exposure patterns in order to determine specific absorption rate (SAR).

This study was designed to test three different exposure routines of pigs head to GSM 900 MHz signal; the 3 simulations were: short exposure of 1-3 seconds for two different exposure levels and a 10 minute continuous exposure. Results were for SAR characterized as the maximum average over 10 grams of tissue mass; 7.3 W/Kg, 31 W/Kg, and 31 W/Kg respectively for the different exposure routines. Uncertainty analysis indicates a 25% variation for the dosimetry.

Toivonen T, Toivo T, Pitkäaho R, Puranen L, Silfverhuth M, Mennander A, Hannula M, Hyttinen J,Jokela K.  Setup and dosimetry for exposing anaesthetised pigs in vivo to 900 MHz GSM mobile phone fields Bioelectromagnetics Ahead of print 4 February 2008 10.1002/bem.20404.  

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Long-term GSM 902 MHz radiation exposure of rats and its effect on induced mammary tumours.

The current study investigates GSM signals on DMBA mammary tumours in rats. Three groups were formed; sham exposure, cage-control group and exposed group of SAR 0.4, 1.3 or 4.0 W/Kg for duration of 6 months. Results indicate that no clear dose–response relation was found.  The cage-control group (no exposure) had either similar or stronger responses than the exposed groups. Because some controversial results are reported in the literature and also the results of the cage-control group in this study, the authors conclude the results of this study are not enough compelling evidence for an RF affect on rat mammary tumour promotion or progression. They could not explain the discrepancies between the existing studies with this current experimentation.
Hruby R, Neubauer G, Kuster N, Frauscher M. (2008). Study on potential effects of “902-MHz GSM-type Wireless Communication Signals” on DMBA-induced mammary tumours in Sprague–Dawley rats. Mutation Research/Genetic Toxicology and Environmental Mutagenesis 649(1-2):34-44.

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No evidence that radiation from mobile phones alters anti-apoptotic bcl-2 protein in rats’ brain and testes.

The objective of the current investigation was to determine whether whole-body exposure from 900 MHz mobile phones radiation could change bcl-2 protein (anti-apoptotic). The experiment was designed with two groups of eight rats (control; sham exposure, and experimental; 20 min. exposure for 1 month). Results confirm that the 900 MHz mobile phone exposure did not produce any effect on anti-apoptotic protein on rats’ brain and testes. The authors suggest that this type of protein could possibly not be involved in the effects of 900 MHz radiation.

Yilmaz F, Dasdag S, Zulkuf Akdag M, Kilinc N. (2008). Whole-Body Exposure of Radiation Emitted from 900 MHz Mobile Phones Does Not Seem to Affect the Levels of Anti-Apoptotic bcl-2 Protein. Electromagnetic Biology and Medicine 27(1): 65-72.

For more see “Research – laboratory – other – cell death (apoptosis)”
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Study investigates non-thermal RF exposure on altered calcium dynamics in stem cells.

It is known that intracellular calcium rapid rise can change cell proliferation, differentiation and cytoskeletal reorganization. Exposure to RF can also affect calcium dynamics. The researchers used neuronal cells from mice stem cell to examine changes in calcium dynamics and elevation in cytosolic calcium. The cells were exposed to non-thermal RF of 700 to 1100 MHz. Results indicate 60% of control cells had about 5 spontaneous calcium spikes in 60 minutes, exposed cells to 800 MHz or 0.5 W/Kg SAR showed a significant increase in calcium spikes to more than 15. Elevation in calcium spikes were explained by N-type calcium channel and phospholipase C enzymes. RF could provide a noninvasive method to assess calcium cellular and molecular activities of cells.

Rao VS, Titushkin IA, Moros EG, Pickard WF, Thatte HS, Cho MR. (2008). Nonthermal Effects of Radiofrequency-Field Exposure on Calcium Dynamics in Stem Cell-Derived Neuronal Cells: Elucidation of Calcium Pathways. Radiat. Res. 169:319-329.

For more see “Research – laboratory – other – calcium efflux”
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No evidence high-frequency radiofrequency (GSM 217 Hz; 2 W/Kg) can produce cellular effects such as HSP70-mediated stress response or primary DNA damage.

Valbonesi and colleagues evaluated the biological effects (expression of proteins and genes; primary DNA damage) of high-frequency radiofrequency on human trophoblast cells. Cells which were exposed to high-frequency radiation did not change (either HSP70 or HSC70 protein or gene expression) and no effect on DNA was noted after high exposure. The results provide evidence that 1 hour exposure to GSM-217 Hz does not affect stress response or DNA damage. The authors suggest more research is called for on different types and duration of GSM signals and trophoblast cells.

Valbonesi P, Franzellitti S, Piano A, Contin A, Biondi C, Fabbri E. (2008). Evaluation of HSP70 Expression and DNA Damage in Cells of a Human Trophoblast Cell Line Exposed to 1.8 GHz Amplitude-Modulated Radiofrequency Fields. Radiat. Res. 169:270-279.

For more see “Research – laboratory – cancer studies”
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A review of stimulation of protein and DNA by electromagnetic fields.

Blank reviews examples of the direct effects of electric and magnetic fields on charge transfer and structural changes. He states the conformational changes due to modification in charge distribution has an important role in membrane transport proteins. He says it is likely that extremely low-frequency range EMF could control as well as amplify biological processes by having an effect on charge distribution.

Blank M. (2008). Protein and DNA Reactions Stimulated by Electromagnetic Fields Electromagnetic Biology and Medicine 27(1):3-23.

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Balzano Q, Swicord M. Comments on neurophysiological effects of mobile phone electromagnetic fields on humans: A comprehensive review BioelectromagneticsAhead of Print28 December 2007 10.1002/bem.20397.  

For more see “Research – clinical – cognitive functions”

Curcio G, Valentini E. Response to comments by Balzano and Swicord on “neurophysiological effects of mobile phone electromagnetic fields on humans: A comprehensive review” Bioelectromagnetics Ahead of print 13 February 2008 10.1002/bem.20398.  

For more see “Research – clinical – cognitive functions”