Effects Of Radiofrequency Exposure Research Articles

The effects of radiofrequency exposure on cognition: A systematic review and meta-analysis of human observational studies

BackgroundWe aimed to assess evidence of long-term effects of exposure to radiofrequency (RF) electromagnetic fields (EMF) on indicators of cognition, including domains of learning and memory, executive function, complex attention, language, perceptual motor ability and social cognition, and of an exposure–response relationship between RF-EMF and cognition. MethodsWe searched PubMed, Embase, PsycInfo and the EMF-Portal on September 30, 2022 without limiting by date or language of publication. We included cohort or case-control studies that evaluated the effects of RF exposure on cognitive function in one or more of the cognitive domains. Studies were rated for risk of bias using the OHAT tool and synthesised using fixed effects meta-analysis. We assessed the certainty of the evidence using the GRADE approach and considered modification by OHAT for assessing evidence of exposures. ResultsWe included 5 studies that reported analyses of data from 4 cohorts with 4639 participants consisting of 2808 adults and 1831 children across three countries (Australia, Singapore and Switzerland) conducted between 2006 and 2017. The main source of RF-EMF exposure was mobile (cell) phone use measured as calls per week or minutes per day.For mobile phone use in children, two studies (615 participants) that compared an increase in mobile phone use to a decrease or no change were included in meta-analyses. Learning and memory. There was little effect on accuracy (mean difference, MD −0.03; 95% CI −0.07 to 0.02) or response time (MD −0.01; 95% CI −0.04 to 0.02) on the one-back memory task; and accuracy (MD −0.02; 95%CI −0.04 to 0.00) or response time (MD −0.01; 95%CI −0.04 to 0.03) on the one card learning task (low certainty evidence for all outcomes). Executive function. There was little to no effect on the Stroop test for the time ratio ((B-A)/A) response (MD 0.02; 95% CI −0.01 to 0.04, very low certainty) or the time ratio ((D-C)/C) response (MD 0.00; 95% CI −0.06 to 0.05, very low certainty), with both tests measuring susceptibility to interference effects. Complex attention. There was little to no effect on detection task accuracy (MD 0.02; 95% CI −0.04 to 0.08), or response time (MD 0.02;95% CI 0.01 to 0.03), and little to no effect on identification task accuracy (MD 0.00; 95% CI −0.04 to 0.05) or response time (MD 0.00;95% CI −0.01 to 0.02) (low certainty evidence for all outcomes). No other cognitive domains were investigated in children.A single study among elderly people provided very low certainty evidence that more frequent mobile phone use may have little to no effect on the odds of a decline in global cognitive function (odds ratio, OR 0.81; 95% CI 0.42 to 1.58, 649 participants) or a decline in executive function (OR 1.07; 95% CI 0.37 to 3.05, 146 participants), and may lead to a small, probably unimportant, reduction in the odds of a decline in complex attention (OR 0.67;95%CI 0.27 to 1.68, 159 participants) and a decline in learning and memory (OR 0.75; 95% CI 0.29 to 1.99, 159 participants). An exposure–response relationship was not identified for any of the cognitive outcomes. DiscussionThis systematic review and meta-analysis found only a few studies that provided very low to low certainty evidence of little to no association between RF-EMF exposure and learning and memory, executive function and complex attention. None of the studies among children reported on global cognitive function or other domains of cognition. Only one study reported a lack of an effect for all domains in elderly persons but this was of very low certainty evidence. Further studies are needed to address all types of populations, exposures and cognitive outcomes, particularly studies investigating environmental and occupational exposure in adults. Future studies also need to address uncertainties in the assessment of exposure and standardise testing of specific domains of cognitive function to enable synthesis across studies and increase the certainty of the evidence. OtherThis review was partially funded by the WHO radioprotection programme and prospectively registered on PROSPERO CRD42021257548.

Effect of radiofrequency exposure on body temperature: Real-time monitoring in normal rats

Radiofrequency radiation (RFR) can generate heat in living organisms. In this study, we monitored the body temperature of healthy animals during RFR exposure in real time using an implantable iButton data logger. A reverberation chamber system for small animals was used for this radiofrequency (RF) exposure in vivo study. Healthy male Sprague-Dawley rats were divided into two groups: with versus without iButton implantation (n = 20 per group). Each group was further divided into a sham-exposed and RF-exposed group (n = 10 per subgroup). Rats were exposed to a 1,760-MHz long-term evolution (LTE) signal in the reverberation chamber system at a whole-body average specific absorption rate of 0 W/kg (sham-exposed) or 4 W/kg (RF-exposed) for 6 h. The body temperature of iButton-implanted rats was recorded using an intraperitoneally implanted iButton every minute over 6 h of RF exposure, whereas that of non-implanted rats was measured directly using a rectal thermometer immediately before and after the 6-h RF exposure period. The temperature values measured by the two types of thermometers were significantly positively correlated (r = 0.63, P < 0.01, linear regression), and changes in body temperatures recorded in iButton-implanted and non-implanted rats measured using two thermometers after 6 h of RF exposure were maintained within <1°C (P = 0.87, general linear model, followed by univariate model). Similar results were obtained for rectal thermometer measurements (P = 0.12, paired t-test). These results suggest that RF exposure at a whole-body average specific absorption rate of 4 W/kg does not induce significant changes in body temperature in healthy rats over a 6-h RF exposure period.

Effects of radiofrequency exposure on in vitro blood-brain barrier permeability in the presence of magnetic nanoparticles

The blood-brain barrier (BBB) remains a major obstacle for the delivery of drugs in the treatment of many neurological diseases. In this study, we aimed to investigate the effects of radiofrequency electromagnetic fields (RF-EMFs) on the permeability of an in vitro BBB model under RF exposure alone, or in the presence of nanoparticles (NPs). For this purpose, an in vitro BBB model was established by seeding human umbilical vein endothelial cells (HUVECs) and human glioblastoma cell line (T98G) on the apical and basolateral sides of the transwell membrane, respectively. The integrity of the BBB model was confirmed by measuring transendothelial electrical resistance (TEER), and a fluorescein isothiocyanate (FITC)-dextran permeability assay was performed when the resistance reached 120 Ω cm2. After the RF-field exposure (13.56 MHz, 80 W, 10 min), we found that FITC-dextran transported across the in vitro BBB was increased 10-fold compared to FITC-dextran transported without an RF-field. This notable phenomenon, which can be called the burst permeability RF effect (BP-RF), has been proposed for the first time in the literature. Subsequently, the effect of the RF-field on BBB permeability was also investigated in the presence of superparamagnetic iron oxide nanoparticles (SPIONs) and magnetic poly(lactic-co-glycolic acid)-polyethylene glycol (PLGA-b-PEG) nanoparticles (m-PNPs). It was found that the amount of both transported NPs on the basolateral sides increased after exposure to the RF-field. As a result, the RF-field can be applied simultaneously during treatment with clinical agents or nanocarriers, improving the permeability of the BBB, which may contribute to therapeutic efficacy of many drugs that are used in neurological diseases.

Effect of Radiofrequency Exposure on Body Temperature: Real-Time Monitoring in Normal Rats

Effect of Radiofrequency Exposure on Body Temperature: Real-Time Monitoring in Normal Rats

The effects of radiofrequency exposure on male fertility and adverse reproductive outcomes: A protocol for two systematic reviews of human observational studies with meta-analysis.

The World Health Organization (WHO) is bringing together evidence on radiofrequency electromagnetic field (RF-EMF) exposure in relation to health outcomes, previously identified as priorities for evaluation by experts in the field, to inform exposure guidelines. A suite of systematic reviews are being undertaken by a network of topic experts and methodologists in order to collect, assess and synthesise data relevant to these guidelines. Here, we present the protocol for the systematic review on the effect of exposure to RF on adverse reproductive outcomes (human observational studies), also referred to as Systematic Review (SR) 3 within the series of systematic reviews currently being commissioned. Following the WHO handbook for guideline development and the COSTER conduct guidelines, we will systematically review the effect of RF-EMF exposure on both male fertility (SR3A) and adverse pregnancy outcomes (SR3B) in human observational studies. Herein we adhere to the PRISMA-P reporting guidelines. We will conduct a broad search for potentially relevant records relevant for both reviews within the following bibliographic databases: MEDLINE; Embase; and EMF Portal. We will also conduct searches of grey literature through relevant databases and organisational websites. RF-EMF experts will also be consulted. We will hand search citation and reference lists of included study records. We will include quantitative human observational studies on the effect of RF-EMF exposure: (in SR3A) in adult male participants on infertility, sperm morphology, concentration or total sperm count or motility; and (in SR3B) in preconception adults or pregnant women on preterm birth, small for gestational age (associated with intrauterine growth restriction), miscarriage, stillbirth and congenital anomalies. Titles, abstracts and then full texts will be screened in blinded duplicate against eligibility criteria with input from a third reviewer as required. Data extraction from included studies will be completed by two reviewers as will risk of bias assessment using the Office of Health Assessment and Translation (OHAT) tool. If appropriate we will undertake meta-analysis to pool effect measures and explore heterogeneity using sub-group analyses or meta-regression as feasible. We will conduct sensitivity analysis to assess the impact of any assumptions made throughout the review process. The OHAT methodology, based on the GRADE guidelines for evidence assessment, will be used to evaluate the certainty of evidence per outcome and to conclude the level of evidence of a health effect. This manuscript details the protocols for two systematic reviews. The aims of publishing details of both protocols are to: pre-specify their scope and methods; reduce the impact of reviewer bias; promote transparency and replicability; and improve the review process. CRD42021265401 (SR3A), CRD42021266268 (SR3B).

Health disturbances and exposure to radiofrequency electromagnetic fields from mobile-phone base stations in French urban areas

The effects of radiofrequency exposure on the health of people living near mobile-phone base stations (MPBSs) have been the subject of several studies since the mid-2000s, with contradictory results.We aimed to investigate the association between measured exposure to radiofrequency electromagnetic fields (RF-EMF) from MPBSs and the presence of self-reported non-specific and insomnia-like symptoms.A cross-sectional survey conducted between 2015 and 2017 in five large cities in France involved 354 people living in buildings located at a distance of 250 m or less from an MPBS and in the main transmit beam of the antennas. Information on environmental concerns, anxiety, and non-specific and insomnia-like symptoms was collected with a questionnaire administrated by telephone. A complete broadband field-meter measurement [100 kHz - 6 GHz] was then made at five points of each dwelling, followed by a spectral analysis at the point of highest exposure, detailing the contribution of each service, including MPBS.The median exposure from MPBS was 0.27 V/m (0.44 V/m for global field), ranging from 0.03 V/m to 3.58 V/m, MPBSs being the main source of exposure for 64% of the dwellings. In this study population, the measured exposure from MPBSs was not associated with self-reported non-specific or insomnia-like symptoms. However, for insomnia-like symptoms, a significant interaction was found between RF-EMF exposure from MPBSs and environmental concerns.These findings do not support the hypothesis of an effect of RF-EMF from MPBSs on non-specific or insomnia-like symptoms in the overall population. Studies are needed to further investigate the positive association observed between exposure from MPBSs and insomnia-like symptoms among people reporting environmental concerns.

Assessment of the potential damaging effect of radiofrequency exposure in children in prospective follow-up (case report series)

Aim: To evaluate the electrical activity of the myocardium and the radiofrequency (RF) application zone resulting from radiofrequency ablation (RFA) performed at an early age.Material and Methods. A prospective follow-up study included three patients who underwent intracardiac electrophysiological study (EPS) and effective RFA of the tachycardia for the first time at an early age. A reintervention was required in one case 12 years after the procedure and in two cases six years after it due to recurrent and new-onset arrhythmias. During the reintervention, electroanatomical mapping was performed to assess the potential damaging effect of radiofrequency exposure in the area of the first ablation.Results. The intracardiac EPS and amplitude bipolar CARTO-reconstruction of primary ablation area were performed during repeated RFA procedure. The study showed that neither zones with a decrease in the amplitude of electrical signal from the myocardium nor silent electrical zones were present ruling out the cicatricial-sclerotic changes in the myocardium in children in the long-term period after RF exposure.Conclusion. The study showed that no increase in the coagulation necrosis zone in the area of primary ablation occurred during the growth of child when the sparing energy and temperature parameters of RFA and the limited number of RF applications were used. Further research in this area is required.

Effects of Radiofrequency Exposure and Co-Exposure on Human Lymphocytes: The Influence of Signal Modulation and Bandwidth

The occurrence of modulation-specific effects after co-exposures to radio-frequency (RF) and other agents has been discussed in the literature. In this paper, the influence of modulation and bandwidth in eliciting the DNA damage of RF alone and in combination with mitomycin-C (MMC) is analyzed in human lymphocytes. Blood cultures from healthy donors were exposed to 1950 MHz, and continuous wave (CW), wideband direct-sequence code division multiple access (WCDMA, 4.5 MHz bandwidth), and additive white Gaussian noise (AWGN, 9 MHz bandwidth) signals were considered. For each signal, specific absorption rate (SAR) values of 0.15, 0.3, 0.6, 1.25 W/kg were tested. RF exposure alone never induced DNA damage in the micronucleus assay. When RF exposure was followed by MMC treatment, the effect depended on modulation and bandwidth. CW exposure never altered the MMC-induced DNA damage, while such damage was reduced when either signals WCDMA at 0.3 W/kg SAR or AWGN at 0.15 and 0.3 W/kg were applied. These results indicate the influence of modulation for the occurrence of the protective effect, with a relation between the bandwidth and the power absorbed by samples. If confirmed in vivo , clinical applications using modulated RF signals could be devised to protect cells from side effects of therapeutic treatments.

Use of TETRA personal radios and sickness absence in the Airwave Health Monitoring Study of the British police forces

BackgroundTerrestrial Trunked Radio (TETRA) is used for radiocommunications among the British police forces. ObjectivesTo investigate association of personal radio use and sickness absence among police officers and staff from the Airwave Health Monitoring Study. MethodsParticipant-level sickness absence records for 26 forces were linked with personal radio use for 32,102 participants. We used multivariable logistic regression to analyse TETRA usage in year prior to enrolment and sickness absence (lasting more than 7 or 28 consecutive days) in the following year and a zero-inflated negative binomial model for analyses of number of sickness absence episodes of any duration (‘spells’) over the same period. In secondary analyses, we looked at an extended period of observation among a sub-cohort with linked data over time, using Cox proportional hazards regression. ResultsMedian personal radio use (year prior to enrolment) was 29.7 min per month (interquartile range 7.5, 64.7) among users. In the year following enrolment there were 25,655 sickness absence spells among 15,248 participants. There were similar risks of sickness absence lasting more than seven days among users and non-users, although among users risk was higher with greater use, odds ratio = 1.04 (95% confidence interval [CI] 1.02 to 1.06) per doubling of radio use. There was no association for sickness absence of more than 28 days. For sickness absence spells, risk was lower among users than non-users (incidence rate ratio = 0.91; 95% CI 0.75 to 1.11), again with higher risk among users for greater radio use. There was no association between radio use and sickness absence in secondary analyses. DiscussionThere were similar or lower risks of sickness absence in TETRA radio users compared with non-users. Among users, the higher risk of sickness absence with greater radio use may reflect working pattern differences among police personnel rather than effects of radiofrequency exposure.

Histopathological, immunohistochemical, and stereological analysis of the effect of Ginkgo biloba (Egb761) on the hippocampus of rats exposed to long-term cellphone radiation.

Cellular phones are major sources of electromagnetic radiation (EMR) that can penetrate the human body and pose serious health hazards. The increasingly widespread use of mobile communication systems has raised concerns about the effects of cellphone radiofrequency (RF) on the hippocampus because of its close proximity to radiation during cellphone use. The effects of cellphone EMR exposure on the hippocampus of rats and the possible counteractive effects of Ginkgo biloba (Egb761) were aimed to investigate. Rats were divided into three groups: Control, EMR, and EMR+Egb761. The EMR and EMR+Egb761 groups were exposed to cellphone EMR for one month. Egb761 was also administered to the EMR+Egb761 group. Specifically, we evaluated the effect of RF exposure on rat hippocampi at harmful EMR levels (0.96 W/kg specific absorption rate [SAR]) for one month and also investigated the possible impact of Ginkgo biloba (Egb761) using stereological, TUNEL-staining, and immunohistochemical methods. An increase in apoptotic proteins (Bax, Acas-3) and a decrease in anti-apoptotic protein (Bcl-2) immunoreactivity along with a decrease in the total granule and pyramidal cell count were noted in the EMR group. A decrease in Bax and Acas-3 and an increase in Bcl-2 immunoreactivity were observed in rats treated with Egb761 in addition to a decrease in TUNEL-stained apoptotic cells and a higher total viable cell number. In conclusion, chronic cellphone EMR exposure may affect hippocampal cell viability, and Egb761 may be used to mitigate some of the deleterious effects.

Mobile phone exposure influences some erythrocytes parameters in vitro. A novel source of preanalytical variability?

The effect of radiofrequency exposure on human health and health care equipment is a matter of ongoing debate. This study was planned to investigate the influence of radiofrequency (RF) waves emitted by a commercial mobile phone on red blood cells (RBC) in vitro. The study population consisted of 16 ostensibly healthy volunteers. Two whole blood specimens were collected from each volunteer. One sample was placed in a plastic rack, 1 cm distant from the chassis of a commercial mobile phone which was activated by a remote phone call lasting 30 min. The other blood sample was placed in another plastic rack, but was kept distant from any type of RF source. The main RBC parameters including RBC count, hematocrit (Ht), hemoglobin, mean corpuscular platelet volume (MPV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC) and RBC distribution width (RDW-CV) were assessed with an Advia 2120. The exposure of whole blood to the mobile phone call significantly increased Ht, hemoglobin, MCV and MCH, whereas the RBC count, MCHC and RDW-CV remained unchanged. A significant correlation was observed between variation of Ht and those of hemoglobin (p=0.008), MCV (p=0.009) or MCH (p=0.037), as well as between hemoglobin and MCV (p=0.048). Increased values were found in 13/16 (81%) samples for both Ht and hemoglobin, 14/16 (88%) samples for MCH and 16/16 (100%) samples for MCV. These results suggest that close mobile phone exposure may be an unappreciated and possibly underestimated cause of preanalytical bias in RBC testing.

Effects of Radio-Frequency Exposure on Synchronous Brain Electrical Activity in Humans [Health Matters}

Reports on the effects of radio frequency exposure on synchronous brain modeling techniques, focusing on electrical activity. Under both normal and abnormal conditions, weak electrical current and voltage signals from nerve cells or neurons in the brain may be recorded noninvasively using electrodes attached to different areas of a person’s scalp Electroencephalography (EEG) is the most commonly used method and protocol for acquiring the spatial-temporal information contained in recordings from multiple scalp electrodes. EEG recordings are used to display wave patterns of electrical activity that occur in the brain and to assess a variety of brain functions in neurological examinations, including sleep patterns (determining different stages of sleep) and assorted psychological disorders.

Validation of self-reported start year of mobile phone use in a Swedish case-control study on radiofrequency fields and acoustic neuroma risk.

The possible effect of radiofrequency exposure from mobile phones on tumor risk has been studied since the late 1990s. Yet, empirical information about recall of the start of mobile phone use among adult cases and controls has never been reported. Limited knowledge about recall errors hampers interpretations of the epidemiological evidence. We used network operator data to validate the self-reported start year of mobile phone use in a case-control study of mobile phone use and acoustic neuroma risk. The answers of 96 (29%) cases and 111 (22%) controls could be included in the validation. The larger proportion of cases reflects a more complete and detailed reporting of subscription history. Misclassification was substantial, with large random errors, small systematic errors, and no significant differences between cases and controls. The average difference between self-reported and operator start year was -0.62 (95% confidence interval: -1.42, 0.17) years for cases and -0.71 (-1.50, 0.07) years for controls, standard deviations were 3.92 and 4.17 years, respectively. Agreement between self-reported and operator-recorded data categorized into short, intermediate and long-term use was moderate (kappa statistic: 0.42). Should an association exist, dilution of risk estimates and distortion of exposure-response patterns for time since first mobile phone use could result from the large random errors in self-reported start year. Retrospective collection of operator data likely leads to a selection of "good reporters", with a higher proportion of cases. Thus, differential recall cannot be entirely excluded.

Whole body exposure to 2.4 GHz WIFI signals: Effects on cognitive impairment in adult triple transgenic mouse models of Alzheimer's disease (3xTg-AD)

The present investigation aimed at evaluating the effects of long-term exposure to WIFI type radiofrequency (RF) signals (2.40GHz), two hours per day during one month at a Specific Absorption Rate (SAR) of 1.60W/kg. The effects of RF exposure were studied on wildtype mice and triple transgenic mice (3xTg-AD) destined to develop Alzheimer's-like cognitive impairment. Mice were divided into four groups: two sham groups (WT, TG; n=7) and two exposed groups (WTS, TGS; n=7). The cognitive interference task used in this study was designed from an analogous human cognitive interference task including the Flex field activity system test, the two-compartment box test and the Barnes maze test. Our data demonstrate for the first time that RF improves cognitive behavior of 3xTg-AD mice. We conclude that RF exposure may represent an effective memory-enhancing approach in Alzheimer's disease.

Sleep EEG alterations: effects of pulsed magnetic fields versus pulse‐modulated radio frequency electromagnetic fields

Studies have repeatedly shown that electroencephalographic power during sleep is enhanced in the spindle frequency range following radio frequency electromagnetic field exposures pulse-modulated with fundamental frequency components of 2, 8, 14 or 217 Hz and combinations of these. However, signals used in previous studies also had significant harmonic components above 20 Hz. The current study aimed: (i) to determine if modulation components above 20 Hz, in combination with radio frequency, are necessary to alter the electroencephalogram; and (ii) to test the demodulation hypothesis, if the same effects occur after magnetic field exposure with the same pulse sequence used in the pulse-modulated radio frequency exposure. In a randomized double-blind crossover design, 25 young healthy men were exposed at weekly intervals to three different conditions for 30 min before sleep. Cognitive tasks were also performed during exposure. The conditions were a 2-Hz pulse-modulated radio frequency field, a 2-Hz pulsed magnetic field, and sham. Radio frequency exposure increased electroencephalogram power in the spindle frequency range. Furthermore, delta and theta activity (non-rapid eye movement sleep), and alpha and delta activity (rapid eye movement sleep) were affected following both exposure conditions. No effect on sleep architecture and no clear impact of exposure on cognition was observed. These results demonstrate that both pulse-modulated radio frequency and pulsed magnetic fields affect brain physiology, and the presence of significant frequency components above 20 Hz are not fundamental for these effects to occur. Because responses were not identical for all exposures, the study does not support the hypothesis that effects of radio frequency exposure are based on demodulation of the signal only.

The Effects on Cells Mobility Due to Exposure to EMF Radiation

Although the important role of the immune system in defending the human body against infections and cancer, only few studies on the possible effects of radiofrequency radiation on the function of human immune cells have been undertaken. The present study was performed to investigate whether radio frequency (RF) field exposure could affect the activity of human immune system cells by studying the activity and behavior of human leukocytes (white blood cells) upon exposure to radiofrequency fields. Human blood Leukocytes were exposed to different temperatures and 1800 MHz RF radiation ( SAR of 1.25 W/Kg, Power density of 0.1 mW/cm2 ) from a mobile phone when placed within a distance of 5 cm from the microscope stage. Our results indicated that when 1800 MHz RF field was applied, the speed increased above the value observed at the same temperature, and the maximum speed exceeded that measured value at any temperature by approximately 50%. The average time for the leukocytes to respond to the effect of RF radiation was approximately 2.5 min. Under the effect of RF exposure, significant change observed in Leukocytes movement direction to be perpendicular to the chemotactic direction and in parallel with the mobile phone position. Also significant change in leukocytes behavior, include changing shape much faster. The cells were shrinking, expanding, and rolling.

Recent Advances in Research on Radiofrequency Fields and Health: 2004–2007

The widespread use of wireless telecommunications devices, particularly mobile phones and wireless networks, has resulted in increased human exposure to radiofrequency (RF) fields. Although national and international agencies have established safety guidelines for exposure to RF fields, concerns remain about the potential for adverse health outcomes to occur in relation to RF field exposure. The extensive literature on RF fields and health was reviewed by a number of authorities, including the Royal Society of Canada (1999). This report is the third in a series of updates to the original report of the Royal Society of Canada, covering the period 2004–2007. In particular, the present study examined new data on (1) dosimetry and exposure assessment, (2) biological effects of RF fields such as enzyme induction, and (3) toxicological effects, including genotoxicity and carcinogenicity. Epidemiological studies of the potential health effects of RF exposure, particularly from mobile phones, were determined, along with human and animal studies of neurological and behavioural effects. Within the last 4 yrs investigators concluded that there is no clear evidence of adverse health effects associated with RF fields, although continued research is recommended to address specific areas of concern, including exposure to RF fields among children using mobile phones. The results of the ongoing 13-country World Health Organization INTERPHONE study of mobile phones may provide important new information on the potential cancer risks associated with mobile phone use.

Influence of a 902.4 MHz GSM signal on the human visual system: Investigation of the discrimination threshold

The proximity of a mobile phone to the human eye raises the question as to whether radiofrequency (RF) electromagnetic fields (EMF) affect the visual system. A basic characteristic of the human eye is its light sensitivity, making the visual discrimination threshold (VDThr) a suitable parameter for the investigation of potential effects of RF exposure on the eye. The VDThr was measured for 33 subjects under standardized conditions. Each subject took part in two experiments (RF-exposure and sham-exposure experiment) on different days. In each experiment, the VDThr was measured continuously in time intervals of about 10 s for two periods of 30 min, having a break of 5 min in between. The sequence of the two experiments was randomized, and the study was single blinded. During the RF exposure, a GSM signal of 902.4 MHz (pulsed with 217 Hz) was applied to the subjects. The power flux density of the electromagnetic field at the subject location (in the absence of the subject) was 1 W/m(2), and numerical dosimetry calculations determined corresponding maximum local averaged specific absorption rate (SAR) values in the retina of SAR(1 g) = 0.007 W/kg and SAR(10 g) = 0.003 W/kg. No statistically significant differences in the VDThr were found in comparing the data obtained for RF exposure with those for sham exposure.

DOSIMETRIC COMPARISON BETWEEN DIFFERENT QUANTITIES FOR LIMITING EXPOSURE IN THE RF BAND: RATIONALE AND IMPLICATIONS FOR GUIDELINES

While source type and its distance from the subject are influential parameters, the fundamental exposure metrics are the physically measurable quantities of currents, external electric field and magnetic field strengths, and incident power density (when appropriate), which induce electric and magnetic fields that bring about the interaction of radiofrequency (RF) electromagnetic energy with biological systems. Induced fields are the primary cause for biological effect of RF exposure, regardless of the mechanism. Thus, in order to achieve a quantitative understanding of biological response, the induced electric field and the derived dosimetric quantities of specific absorption rate (SAR) and current density must be quantified and correlated with the observed phenomenon. In the established exposure guidelines, reference levels expressed in terms of physical quantities are introduced for practical exposure assessment purposes since the basic restrictions are often specified as dosimetric quantities that may be impractical to measure. The dosimetric quantity SAR, current density, and their determinations are tissue-type dependent and require a region of specific tissue mass for averaging. Thus, a smaller averaging region is scientifically more relevant and precise. It is emphasized that the sensitivity and resolution of present-day computational resources and experimental measurement techniques can provide accurate SAR values with a spatial resolution on the order of a 1 mm, in dimensions. Furthermore, most exposure guidelines are promulgated on a 4 W kg SAR to prevent any whole-body exposure from raising the body temperature to 1 degrees C above the norm at 37 degrees C. Special guidance may be needed for higher ambient temperature and humidity variations.

Thermal stress and radiation protection principles

Exposure to radiofrequency (RF) fields can occur in residential, occupational and medical settings. Since many technologies use RF fields, it is important to fully investigate their effects on the human body. Since the demonstrated effect of RF exposure is heating, it is important to critically evaluate studies of elevated temperature effects on the human body, from the cellular and tissue level to the whole body level, including potential effects on the susceptible groups such as the very young and the very old. WHO convened a Workshop in the Spring of 2002 on the subject of Adverse Temperature Levels in the Human. The goal of the workshop was to evaluate most recent data useful for the development of science-based RF exposure limits. This paper outlines radiation protection principles that underline such an evaluation. It discusses the quality of literature needed for sound scientific reviews, provides the hierarchy of scientific evidence used to establish effects, distinguish between biological effects and adverse health consequences and indicates how evidence is evaluated. In addition, criteria for determining the most sensitive effects, the value of an effect that has a dose-response and methods of extrapolation are also described. Finally, the need to account for scientific uncertainty in the formulation of guidance on exposure is discussed.