Effect on human attention of exposure to the electromagnetic field emitted by mobile phones

The more academic burnout students got, the more problematic mobile phone use they suffered? A meta-analysis of mainland Chinese adolescents and young adults

Introduction

In recent years, the relationship between academic burnout (AB) and problematic mobile phone use (PMPU) has become the hot issue of scholars, and a lot of related research has been carried out, but the results are different. Most studies showed that there was a significant positive correlation between AB and PMPU. However, some studies showed that the relationship between AB and PMPU was not significant. While this study aimed at exploring the relationship between AB and PMPU, as well as the influence of some moderating factors (region, age, gender, publication year, the measurement instrument) on them.

Methods

According to the searching process for studies of PRISMA, we searched the related studies on AB and PMPU in Mainland China from January 2012 to November 2022 from CNKI, Wanfang Data, Chongqing VIP Information Co., Ltd. (VIP), Baidu scholar, ProQuest dissertations, Taylor & Francis, Springer, Web of Science, Google Scholar, EBSCO and PsyclNFO. Eventually, 50 studies were included in the meta-analysis, involving 38,488 subjects, with the sample size ranging from 193 to 2,260. CMA 3.0 was used to analyze the overall effect and test the moderating effect.

Results

The result shows that the relationship between AB and PMPU can be considered as a moderate correlation (r = 0.414, 95%CI [0.384, 0.443]), and moderator analysis shows that the relationship between AB and PMPU was moderated by the measurement instrument and publication year.

Discussion

Specifically, when the Mobile Phone Addiction Tendency Scale and the Smartphone Addiction Scale for College Students were used as PMPU measurement tools, the correlation coefficients between AB and PMPU were higher. When the publication year was used as a moderating variable, the relationship between AB and PMPU increased over the years. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022347277, identifier PROSPERO CRD42022347277.

Systematic review of the physiological and health-related effects of radiofrequency electromagnetic field exposure from wireless communication devices on children and adolescents in experimental and epidemiological human studies

BACKGROUND

For more than 20 years, the potential health risks of radiofrequency electromagnetic field (RF EMF) exposure from mobile communication devices on children and adolescents have been examined because they are considered sensitive population groups; however, it remains unclear whether such exposure poses any particular risk to them.

OBJECTIVES

The aim of this review was to systematically analyze and evaluate the physiological and health-related effects of RF EMF exposures from wireless communication devices (mobile phones, cordless phones, Bluetooth, etc.) on children and adolescents.

METHODS

This review was prepared according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Methodological limitations in individual studies were assessed using the Office of Health Assessment and Translation (OHAT) Risk-of-Bias Rating Tool for Human and Animal Studies.

RESULTS

A total of 42 epidemiological and 11 experimental studies were eligible for this review. Most of the studies displayed several methodological weaknesses that limited the internal validity of the results. Due to a lack of consistency regarding the outcomes as well as the lack of scientific rigor in most reviewed studies, the body of evidence for the effects of RF EMF of mobile communication devices on subjective symptoms, cognition, and behavior in children and adolescents was low to inadequate. Evidence from the studies investigating early childhood development, brain activity, cancer, and physiological parameters was considered inadequate for drawing conclusions about possible effects.

DISCUSSION

Overall, the body of evidence allows no final conclusion on the question whether exposure to RF EMF from mobile communication devices poses a particular risk to children and adolescents. There has been rapid development in technologies generating RF EMF, which are extensively used by children and adolescents. Therefore, we strongly recommend high-quality systematic research on children and adolescents, since they are generally considered as sensitive age groups.

Recent advances in the effects of microwave radiation on brains

This study concerns the effects of microwave on health because they pervade diverse fields of our lives. The brain has been recognized as one of the organs that is most vulnerable to microwave radiation. Therefore, in this article, we reviewed recent studies that have explored the effects of microwave radiation on the brain, especially the hippocampus, including analyses of epidemiology, morphology, electroencephalograms, learning and memory abilities and the mechanisms underlying brain dysfunction. However, the problem with these studies is that different parameters, such as the frequency, modulation, and power density of the radiation and the irradiation time, were used to evaluate microwave radiation between studies. As a result, the existing data exhibit poor reproducibility and comparability. To determine the specific dose-effect relationship between microwave radiation and its biological effects, more intensive studies must be performed.

Mobile phone use, behavioural problems and concentration capacity in adolescents: A prospective study

The aim of this study is to prospectively investigate whether exposure to radiofrequency electromagnetic fields (RF-EMF) emitted by mobile phones and other wireless communication devices is related to behavioural problems or concentration capacity in adolescents. The HERMES (Health Effects Related to Mobile phonE use in adolescentS) study sample consisted of 439 Swiss adolescents aged 12-17 years. Behavioural problems were assessed using the Strengths and Difficulties Questionnaire (SDQ), concentration capacity of the adolescents was measured by means of a standardized computerized cognitive test named FAKT. Cross-sectional and longitudinal (1year of follow-up) analyses were performed to investigate possible associations between behavioural problems and concentration capacity and different exposure measures: self-reported and operator-recorded wireless communication device use, cumulative RF-EMF brain and whole body dose and measured personal RF-EMF exposure. In the cross-sectional analyses behavioural problems were associated with several self-reported wireless device use measures but not operator-recorded mobile phone use measures, concentration capacity was associated with several self-reported and operator-recorded exposures. The longitudinal analyses point towards absence of associations. The lack of consistent exposure-response patterns in the longitudinal analyses suggests that behavioural problems and concentration capacity are not affected by the use of wireless communication devices or RF-EMF exposure. Information bias and reverse causality are likely explanations for the observed cross-sectional findings.

Association between mobile phone use and inattention in 7102 Chinese adolescents: a population-based cross-sectional study

BACKGROUND

The dramatic growth of mobile phone (MP) use among young people has increased interest in its possible health hazards in this age group. The aim of this cross-sectional study was to investigate the association between MP use and inattention in adolescents.

METHODS

A total of 7720 middle school students were involved in this cross-sectional study. Inattention was assessed as defined for the Attention Deficit component of Attention deficit/Hyperactivity disorder (ADHD) by the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev. [DSM-IV-TR]). The demographic characteristics and information on MP use were included in the questionnaire. Chi-square tests and logistic regression models were used to analyze the data.

RESULTS

In total, 7102 (91.99%) valid questionnaires were obtained. After adjusted for confounders, inattention in adolescents was significantly associated with MP ownership, the time spent on entertainment on MP per day, the position of the MP during the day and the mode of the MP at night. The strongest association between inattention and the time spent on the MP was among students who spent more than 60 minutes per day playing on their MP.

CONCLUSIONS

Our study shows some associations between MP use and inattention in Chinese adolescents. Decreasing MP usage to less than 60 minutes per day may help adolescents to stay focused and centered.

Looking at the other side of the coin: the search for possible biopositive cognitive effects of the exposure to 900 MHz GSM mobile phone radiofrequency radiation

Although exposure to electromagnetic radiation in radiofrequency range has caused a great deal of concern globally, radiofrequency radiation has many critical applications in both telecommunication and non-communication fields. The induction of adaptive response phenomena by exposure to radiofrequency radiation as either increased resistance to a subsequent dose of ionizing radiation or resistance to a bacterial infection has been reported recently. Interestingly, the potential beneficial effects of mobile phone radiofrequency radiation are not only limited to the induction of adaptive phenomena. It has previously been indicated that the visual reaction time of university students significantly decreased after a 10 min exposure to radiofrequency radiation emitted by a mobile phone. Furthermore, it has been revealed that occupational exposures to radar radiations decreased the reaction time in radar workers. Based on these findings, it can be hypothesized that in special circumstances, these exposures might lead to a better response of humans to different hazards. Other investigators have also provided evidence that confirms the induction of RF-induced cognitive benefits. Furthermore, some recent reports have indicated that RF radiation may play a role in protecting against cognitive impairment in Alzheimer's disease. In this light, a challenging issue will arise if there are other RF-induced stimulating effects. It is also challenging to explore the potential applications of these effects. Further research may shed light on dark areas of the health effects of short and long-term human exposure to radiofrequency radiation.

Lipid integration in neurodegeneration: an overview of Alzheimer's disease

Various types of lipids and their metabolic products associated with the biological membrane play a crucial role in signal transduction, modulation, and activation of receptors and as precursors of bioactive lipid mediators. Dysfunction in the lipid homeostasis in the brain could be a risk factor for the many types of neurodegenerative disorders, including Alzheimer's disease, Huntington's disease, Parkinson's disease, and amyotrophic lateral sclerosis. These neurodegenerative disorders are marked by extensive neuronal apoptosis, gliosis, and alteration in the differentiation, proliferation, and development of neurons. Sphingomyelin, a constituent of plasma membrane, as well as its primary metabolite ceramide acts as a potential lipid second messenger molecule linked with the modulation of various cellular signaling pathways. Excessive production of reactive oxygen species associated with enhanced oxidative stress has been implicated with these molecules and involved in the regulation of a variety of different neurodegenerative and neuroinflammatory disorders. Studies have shown that alterations in the levels of plasma lipid/cholesterol concentration may result to neurodegenerative diseases. Alteration in the levels of inflammatory cytokines and mediators in the brain has also been found to be implicated in the pathophysiology of neurodegenerative diseases. Although several mechanisms involved in neuronal apoptosis have been described, the molecular mechanisms underlying the correlation between lipid metabolism and the neurological deficits are not clearly understood. In the present review, an attempt has been made to provide detailed information about the association of lipids in neurodegeneration especially in Alzheimer's disease.

Hyperthermic effects on behavior

This review focuses upon the past 8 years of research on hyperthermic effects on behavior. Heat stress and heat stoke become severe conditions when body temperatures exceed 40°C as this can lead to delirium, convulsions, coma, and death. The animal literature indicates that hyperthermia can increase glutamatergic and decrease GABAergic neurotransmission. Interestingly, µ-opiate receptor antagonists can attenuate the morphological and biochemical changes in brain, as well as, ameliorate some behavioral deficits induced by heart stress. In humans, heat stress can produce detrimental effects on motor and cognitive performance. Since most cognitive tasks require a motor response, some cognitive deficiencies may be attributed to decreased motor performance. Although hyperthermia may exert more deleterious effects on complex than simple cognitive tasks, systematic studies are needed to examine the effects of different levels and durations of hyperthermia (irrespective of dehydration) on cognition. Additionally, body temperatures should be carefully monitored where controls are run for baseline or brief exposures to a hyperthermic environment. Acute radiofrequency exposure can disrupt behavior when body temperatures increase >1°C with whole body SAR between 3.2-8.4 W/kg and time-averaged power densities at 8-140 mW/cm(2). Effects of lower levels of radiation are conflicting and some experiments fail to replicate even with the original investigators. This suggests either that brief exposure to the radiation is at a threshold where some individuals are affected while others are not, or that these levels are innocuous. Nevertheless, thermal changes appear to account for almost all of the behavioral effects reported.

No effects of short-term exposure to mobile phone electromagnetic fields on human cognitive performance: a meta-analysis

During recent years, a large number of studies on the effects of electromagnetic fields emitted by cellular mobile phones on human cognitive performance have been carried out. However, the results have been ambiguous. We carried out the current meta-analysis in order to investigate the impact of electromagnetic fields emitted by mobile phones on human cognition. Seventeen studies were included in the meta-analysis as they fulfill several requirements such as single- or double-blind experimental study design, and documentation of means and standard deviations of dependent variables. The meta-analysis was carried out as a group comparison between exposed and non-exposed subjects. No significant effects of electromagnetic fields emitted by Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS) mobile phones were found. Cognitive abilities seem to be neither impaired nor facilitated. Results of the meta-analysis suggest that a substantial short-term impact of high frequency electromagnetic fields emitted by mobile phones on cognitive performance can essentially be ruled out.

Effects of W-CDMA 1950 MHz EMF emitted by mobile phones on regional cerebral blood flow in humans

Use of the third generation mobile phone system is increasing worldwide. This is the first study to investigate the effects of the third generation system on regional cerebral blood flow (rCBF) in humans. We compared effects of the electromagnetic field (EMF) emitted from the Wideband Code Division Multiple Access (W-CDMA) cellular system versus sham control exposure on rCBF in humans. Nine healthy male volunteers participated in this study. Positron emission tomography (PET) scans were obtained before, during, and after unilateral 30 min EMF exposure. The subtraction analysis revealed no significant rCBF changes caused by the EMF conditions compared with the sham exposure, suggesting that EMF emitted by a third generation mobile phone does not affect rCBF in humans.

Effects of radiofrequency electromagnetic fields on the human nervous system

The effects of exposure to radiofrequency electromagnetic fields (EMF), specifically related to the use of mobile telephones, on the nervous system in humans have been the subject of a large number of experimental studies in recent years. There is some evidence of an effect of exposure to a Global System for Mobile Telecommunication (GSM)-type signal on the spontaneous electroencephalogram (EEG). This is not corroborated, however, by the results from studies on evoked potentials. Although there is some evidence emerging that there may be an effect of exposure to a GSM-type signal on sleep EEG, results are still variable. In summary, exposure to a GSM-type signal may result in minor effects on brain activity, but such changes have never been found to relate to any adverse health effects. No consistent significant effects on cognitive performance in adults have been observed. If anything, any effect is small and exposure seems to improve performance. Effects in children did not differ from those in healthy adults. Studies on auditory and vestibular function are more unequivocal: neither hearing nor the sense of balance is influenced by short-term exposure to mobile phone signals. Subjective symptoms over a wide range, including headaches and migraine, fatigue, and skin itch, have been attributed to various radiofrequency sources both at home and at work. However, in provocation studies a causal relation between EMF exposure and symptoms has never been demonstrated. There are clear indications, however, that psychological factors such as the conscious expectation of effect may play an important role in this condition.

ELECTROENCEPHALOGRAPHIC, PERSONALITY, AND EXECUTIVE FUNCTION MEASURES ASSOCIATED WITH FREQUENT MOBILE PHONE USE

The present study employs standardized data acquired from the Brain Resource International Database to study the relationship between mobile phone usage, personality, and brain function (n = 300). Based on the frequency and duration of mobile phone usage, three groups were formed. The findings suggest a subtle slowing of brain activity related to mobile phone use that is not explained by differences in personality. These changes are still within normal physiological ranges. Better executive function in mobile phone users may reflect more focused attention, possibly associated with a cognitive training effect (i.e., frequently making phone calls in distracting places), rather than a direct effect of mobile phone use on cognition.

No effect of an UMTS mobile phone-like electromagnetic field of 1.97 GHz on human attention and reaction time

Several studies in the past reported influences of electromagnetic emissions of GSM phones on reaction time in humans. However, there are currently only a few studies available dealing with possible effects of the electromagnetic fields emitted by UMTS mobile phones. In our study, 40 healthy volunteers (20 female, 20 male), aged 26.0 years (range 21-30 years) underwent four different computer tests measuring reaction time and attention under three different UMTS mobile phone-like exposure conditions (two exposure levels plus sham exposure). Exposure of the subjects was accomplished by small helical antennas operated close to the head and fed by a generic signal representing the emissions of a UMTS mobile phone under constant receiving conditions as well as under a condition of strongly varying transmit power. In the high exposure condition the resulting peak spatial average exposure of the test subjects in the cortex of the left temporal lobe of the brain was 0.63 W/kg (min. 0.25 W/kg, max. 1.49 W/kg) in terms of 1 g averaged SAR and 0.37 W/kg (min. 0.16 W/kg, max. 0.84 W/kg) in terms of 10 g averaged SAR, respectively. Low exposure condition was one-tenth of high exposure and sham was at least 50 dB below low exposure. Statistical analysis of the obtained test parameters showed that exposure to the generic UMTS signal had no statistically significant immediate effect on attention or reaction. Therefore, this study does not provide any evidence that exposure of UMTS mobiles interferes with attention under short-term exposure conditions.

Are there modulated electromagnetic field effects on human conscious perception during attentional blink test?

The aim of this study was to experimentally examine the effects of low-level modulated electromagnetic fields on human central nervous system function utilizing the phenomenon of attentional blink. Twenty healthy volunteers were exposed to 450 MHz electromagnetic field (EMF) modulated with 40 Hz stimulation. During the exposure the subjects were presented rapid serial visual presentation (RSVP) sequence, which consisted of 8 letters (stimuli) and two numbers (targets - T1 and T2). The task was to detect two target stimuli out of the sequence. The experiment protocol consisted of two sessions -- 100 trials each. One session was done under EMF exposure condition and another under sham condition. The attentional blink phenomenon can be described as impairment of the identification of the second of two targets if it is presented less than about 500 ms after the first. Resulting data were statistically analyzed using a two-tailed Student's t-test. The results showed that EMF had no immediate effect on attentional blink characteristics of human perception.

Recent advances in research on radiofrequency fields and health: 2001-2003

The widespread use of wireless telecommunications devices, particularly mobile phones, 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 has been reviewed by a number of authorities, including the Royal Society of Canada (1999), the European Commission's Scientific Committee on Toxicity, Ecotoxicity, and the Environment (CSTEE, 2001), the British Medical Association (2001), the Swedish Radiation Protection Authority (Boice & McLaughlin, 2002), and the Health Council of The Netherlands (2002). This report provides an update on recent research results on the potential health risks of RF fields since the publication of the Royal Society of Canada report in 1999 (See Krewski et al., 2001a) and our previous 2001 update (Krewski et al., 2001b), covering the period 2001-2003. The present report examines new data on dosimetry and exposure assessment, biological effects such as enzyme induction, and toxicological effects, including genotoxicity, carcinogenicity, and testicular and reproductive outcomes. Epidemiological studies of mobile phone users and occupationally exposed populations are examined, along with human and animal studies of neurological and behavioral effects. All of the authoritative reviews completed within the last 2 yr have concluded that there is no clear evidence of adverse health effects associated with RF fields. However, following a recent review of nine epidemiological studies of mobile phones and cancer, Kundi et al. (2004) concluded that the possibility of an enhanced cancer risk cannot be excluded. These same reviews support the need for further research to clarify the possible associations between RF fields and adverse health outcomes that have appeared in some reports. The results of the ongoing World Health Organization (WHO) study of mobile phones will provide important new information in this regard.

Effects of thirty-minute mobile phone exposure on saccades

OBJECTIVE

To investigate whether exposure to pulsed high-frequency electromagnetic field (pulsed EMF) emitted by a mobile phone has short-term effects on saccade performances.

METHODS

A double blind, counterbalanced crossover design was employed. In 10 normal subjects, we studied the performance of visually guided saccade (VGS), gap saccade (GAP), and memory guided saccade (MGS) tasks before and after exposure to EMF emitted by a mobile phone for thirty minutes or sham exposure. We also implemented a hand reaction time (RT) task in response to a visual signal.

RESULTS

With the exception of VGS and MGS latencies, the parameters of VGS, GAP and MGS tasks were unchanged before and after real or sham EMF exposure. In addition, the latencies of VGS and MGS did not change differently after real and sham exposure. The hand RT shortened with the repetition of trials, but again this trend was of similar magnitude for real and sham exposures.

CONCLUSIONS

Thirty minutes of mobile phone exposure has no significant short-term effect on saccade performances.

SIGNIFICANCE

This is the first study to investigate saccade performance in relation to mobile phone exposure. No significant effect of mobile phone use was demonstrated on the performance of various saccade tasks, suggesting that the cortical processing for saccades and attention is not affected by exposure to EMF emitted by a mobile phone.

Effects of thirty-minute mobile phone use on visuo-motor reaction time

OBJECTIVE

To investigate whether exposure to pulsed high-frequency electromagnetic field (pulsed EMF) emitted by a mobile phone has short-term effects on the visuo-motor choice reaction time (RT) and movement time (MT).

METHODS

A double blind, counterbalanced crossover design was employed. In 16 normal subjects, we studied the performance of a visuo-motor precued choice reaction time task (PCRT) before and after exposure to EMF emitted by a mobile phone for 30 minutes or sham exposure.

RESULTS

The RTs and MTs under different conditions of precue information were not affected by exposure to pulsed EMF emitted by a mobile phone or by sham phone use.

CONCLUSIONS

Thirty minutes of mobile phone use has no significant short-term effect on the cortical visuo-motor processing as studied by the present PCRT task.

SIGNIFICANCE

This is the first study to investigate visuo-motor behavior in relation to mobile phone exposure. No significant effect of mobile phone use was demonstrated on the performance of the visuo-motor reaction time task.

Subjective symptoms, sleeping problems, and cognitive performance in subjects living near mobile phone base stations

BACKGROUND

The erection of mobile telephone base stations in inhabited areas has raised concerns about possible health effects caused by emitted microwaves.

METHODS

In a cross-sectional study of randomly selected inhabitants living in urban and rural areas for more than one year near to 10 selected base stations, 365 subjects were investigated. Several cognitive tests were performed, and wellbeing and sleep quality were assessed. Field strength of high-frequency electromagnetic fields (HF-EMF) was measured in the bedrooms of 336 households.

RESULTS

Total HF-EMF and exposure related to mobile telecommunication were far below recommended levels (max. 4.1 mW/m2). Distance from antennae was 24-600 m in the rural area and 20-250 m in the urban area. Average power density was slightly higher in the rural area (0.05 mW/m2) than in the urban area (0.02 mW/m2). Despite the influence of confounding variables, including fear of adverse effects from exposure to HF-EMF from the base station, there was a significant relation of some symptoms to measured power density; this was highest for headaches. Perceptual speed increased, while accuracy decreased insignificantly with increasing exposure levels. There was no significant effect on sleep quality.

CONCLUSION

Despite very low exposure to HF-EMF, effects on wellbeing and performance cannot be ruled out, as shown by recently obtained experimental results; however, mechanisms of action at these low levels are unknown.

Study of effects of low level microwave field by method of face masking

The aim of this study was to examine experimentally effects of low level, modulated microwaves on human central nervous system function utilizing the phenomenon of visual masking. Ten healthy volunteers, four males and six females, were exposed to electromagnetic field (450 MHz, 0.16 mW/cm2) with 7 Hz modulation frequency. Two photo series (visual stimuli) of unfamiliar, young male faces were presented to the subjects, one picture after another. All the photos were frontal views of unfamiliar faces, which could be recognized only by their unique combinations of features. The task was to identify the pictures from a group of six photos and to decide which order they were presented in. The phenomenon of visual masking is revealed as anamorphosis in subject's perception of two instantaneous visual stimuli presented within a short time interval. When both stimuli were to be recognized correctly and put in the right order, there was a statistically significant difference (P < 0.05) between the identification of the stimulus with microwave electromagnetic field and sham exposure. Recognition of both stimuli in a pair was better under the sham exposure conditions but the actual difference was only 5%. It was concluded that early stages of visual information processing are overwhelmingly robust and routine (and adaptively significant) activities, so that the low level 7 Hz modulated electromagnetic field effects exerted upon it are extremely weak.

Cellular telephone use among primary school children in Germany

BACKGROUND

There is some concern about potential health risks of cellular telephone use to children. We assessed data on how many children own a cellular telephone and on how often they use it in a population-based sample.

METHODS

We carried out a cross-sectional study among children in their fourth elementary school year, with a median-age of 10 years. The study was carried out in Mainz (Germany), a city with about 200,000 inhabitants. The study base comprised all 37 primary schools in Mainz and near surroundings. Altogether, 1933 children from 34 primary schools took part in the survey (participation rate of 87.8%).

RESULTS

Roughly a third of all children (n = 671, 34.7%) reported to own a cellular telephone. Overall, 119 (6.2%) children used a cellular telephone for making calls at least once a day, 123 (6.4%) used it several times a week and 876 (45.3%) children used it only once in a while. The remaining 805 (41.6%) children had never used a cellular telephone. The probability of owning a cellular telephone among children was associated with older age, being male, having no siblings, giving full particulars to height and weight, more time spent watching TV and playing computer games, being picked up by their parents from school by car (instead of walking or cycling) and going to bed late. The proportion of cellular telephone owners was somewhat higher in classes with more children from socially disadvantaged families.

CONCLUSIONS

Our study shows that both ownership of a cellular telephone as well as the regular use of it are already quite frequent among children in the fourth grade of primary school. With regard to potential long-term effects, we recommend follow-up studies with children.

No effect on cognitive function from daily mobile phone use

The increasing use of mobiles phones (MP) has raised the problem of the effects of daily electromagnetic fields (EMF) exposure on human health. To date several studies have been published concerning the effects of acute MP exposure on psychomotor performances. This study investigated the effects of daily exposure to GSM 900 type MP on cognitive function. Fifty-five subjects (27 male and 28 female) were divided into two groups: a group with MP switched on and a group with MP switched off. The two groups were matched according to age, gender, and IQ. This double blind study lasted for 45 days and was divided in three periods: baseline (BLP, 2 days), exposure (EP, 27 days), and recovery (RP, 13 days). Subjects were exposed during EP and sham exposed during RP for 2 h/day, 5 days/week. The neuropsychological test battery composed of 22 tasks screened four neuropsychological categories: information processing, attention capacity, memory function, and executive function. This neuropsychological battery was performed four times on day 2 (BLP), day 15 (EP), day 29 (EP), and day 43 (RP). Our results indicate that daily MP use has no effect on cognitive function after a 13-h rest period.

Neurobehavioural effects of electromagnetic fields

Very few laboratory studies in children have explored the effects of exposure to low level electromagnetic fields (EMFs) on neurobehavioural function. Studies investigating effect on neurotransmitters, cognitive function and brain activity in adults and animals indicate that acute exposure to EMFs does not appear to engender any consistent physiological or behavioural impairment although a few subtle effects may occur. This suggests that exposure of children to low level EMFs may not cause significant detrimental effects on brain function. However the available evidence is not sufficient to draw any definite conclusions, and further laboratory studies are required. In particular, experiments investigating the effects of radiofrequency (RF) fields on the performance of well-characterised cognitive and behavioural tasks by immature and developing animals are recommended, if studies with children cannot be performed for ethical and practical reasons.

Electromagnetic field emitted by 902 MHz mobile phones shows no effects on children's cognitive function

The present study investigated the potential effects of a standard 902 MHz global system for mobile communication (GSM) mobile phone on 10-14 years old children's cognitive function. A total of 32 children (16 boys, 16 girls) participated with their own and parental consent. The subjects were 10-14 years old (mean 12.1 years, SD 1.1). They performed a battery of cognitive tests twice in a counter-balanced order: once while exposed to an active mobile phone and once during exposure to an inactive phone. The tests were selected from those we used earlier with adults. The statistical analyses showed no significant differences between the mobile phone off and on conditions in reaction times and accuracy over all tests or in any single test. It was concluded that a standard mobile phone has no effect on children's cognitive function as measured by response speed and accuracy. The present results challenge some earlier findings suggesting that the electromagnetic field (EMF) created by an active mobile phone would facilitate cognitive functioning.

No influence on selected parameters of human visual perception of 1970 MHz UMTS-like exposure

In recent years several studies regarding possible effects of radio frequency (RF) electromagnetic fields (EMFs) on cognitive brain function were reported. In many of these studies on awake humans the working tasks were presented visually to the test subjects, e.g., on a computer screen. Therefore, the question of where in the chain of visual perception, brain processing and response a possible effect could be induced seems to be of interest. In this study, possible effects of exposure to a generic 1.97 GHz UMTS-like signal on human visual perception were investigated in a double blinded, crossover study including 58 healthy volunteer subjects (29 male, 29 female), aged 29 +/- 5.1 years (mean +/- SD). Each test subject underwent a battery of four different clinical tests three times (two different exposure levels and sham exposure) to assess selected parameters of visual perception. The generic signals applied to the subjects' head represented the RF emissions of an UMTS mobile phone under constant receiving conditions and the under condition of strongly varying transmit power, i.e., the signal envelope contained low frequency components. In the high exposure condition the resulting average exposure of the test subjects in the cortex of the left temporal lobe of the brain was 0.63 W/kg (1 g averaged SAR) and 0.37 W/kg (10 g averaged SAR). Low exposure condition was one tenth of high exposure and sham was at least 50 dB (corresponding to a factor of 100,000) below low exposure. Statistical evaluation of the obtained test results revealed no statistically significant differences in the investigated parameters of visual perception between the exposure conditions and sham exposure.

Effect of 902 MHz mobile phone transmission on cognitive function in children

We examine whether a standard mobile exposure at 902 MHz has a significant effect on cognitive function in 18 children 10-12 years of age. These were in a single group in which each child was given a single training session and then three test sessions in a randomized, three-way crossover design, using the cognitive drug research (CDR) cognitive assessment system. Exposures were 0, 0.025, or 0.25 W from a standard Nokia 3110 mobile phone handset mounted on a plastic headset in normal use position. The results of testing showed that the baseline (0 W) performance for the reaction time measurements was considerably slower than for the comparable measures in adult. There was a tendency for reaction time to be shorter during exposure to radiation than in the sham (baseline) condition, an effect that was most marked for simple reaction time. However, no effects reached statistical significance after Bonferroni correction. Therefore, we conclude that this study on 18 children did not replicate our earlier finding in adults that exposure to microwave radiation was associated with a reduction in reaction time. It should be noted that the present study investigated the effects of radiation from a GSM handset, whereas in our previous study the effect on reaction time was observed only with a more powerful analogue handset.

Gender related differences on the EEG during a simulated mobile phone signal

The present study investigated the gender-related influence of electromagnetic fields (EMF), similar to that emitted by mobile phones, on brain activity. Ten women and nine men performed a short memory task (Wechsler test), both without (baseline) and with exposure to a 900 MHz signal. The EEG energy of the total waveform and the alpha, beta, delta and theta; rhythms were calculated from the recordings of 15 scalp electrodes. Baseline EEG energy of males was greater than that of females, while exposure to EMF decreased EEG energy of males and increased that of females. Memory performance was invariant to EMF exposure and gender influences. These findings indicate that EMF may exert a gender-related nfluence on brain activity.

902 MHz mobile phone does not affect short term memory in humans

We studied the effects of an electromagnetic field (EMF) as emitted by a 902 MHz mobile phone on human short term memory. This study was a replication with methodological improvements to our previous study. The improvements included multi-centre testing and a double blind design. A total of 64 subjects (32 men) in two independent laboratories performed a short term memory task (n-back) which poses a varying memory load (0-3 items) on the subjects' memory. They performed the task twice, once each under EMF and sham exposure. Reaction times (RTs) and accuracy of the responses were recorded. The order of exposure and memory load conditions were counterbalanced across subjects and gender. There were no statistically significant differences in performance between the two laboratories. We could not replicate our previous results: the EMF had no effect on RTs or on the accuracy of the subjects' answers. The inability to replicate previous findings could have been caused by lack of actual EMF effects or the magnitude of effects being at the sensitivity threshold of the test used.

Microwave effects on the nervous system

Studies have evaluated the electroencephalography (EEG) of humans and laboratory animals during and after Radiofrequency (RF) exposures. Effects of RF exposure on the blood-brain barrier (BBB) have been generally accepted for exposures that are thermalizing. Low level exposures that report alterations of the BBB remain controversial. Exposure to high levels of RF energy can damage the structure and function of the nervous system. Much research has focused on the neurochemistry of the brain and the reported effects of RF exposure. Research with isolated brain tissue has provided new results that do not seem to rely on thermal mechanisms. Studies of individuals who are reported to be sensitive to electric and magnetic fields are discussed. In this review of the literature, it is difficult to draw conclusions concerning hazards to human health. The many exposure parameters such as frequency, orientation, modulation, power density, and duration of exposure make direct comparison of many experiments difficult. At high exposure power densities, thermal effects are prevalent and can lead to adverse consequences. At lower levels of exposure biological effects may still occur but thermal mechanisms are not ruled out. It is concluded that the diverse methods and experimental designs as well as lack of replication of many seemingly important studies prevents formation of definite conclusions concerning hazardous nervous system health effects from RF exposure. The only firm conclusion that may be drawn is the potential for hazardous thermal consequences of high power RF exposure.

Human electrophysiological and cognitive effects of exposure to ELF magnetic and ELF modulated RF and microwave fields: a review of recent studies

The investigation of weak (<500 microT), extremely low frequency (ELF, 0-300 Hz) magnetic field (MF) exposure upon human cognition and electrophysiology has yielded incomplete and contradictory evidence that MFs interact with human biology. This may be due to the small number of studies undertaken examining ELF MF effects upon the human electroencephalogram (EEG), and the associated analysis of evoked related potentials (ERPs). Relatively few studies have examined how MF exposure may affect cognitive and perceptual processing in human subjects. The introduction of this review considers some of the recent studies of ELF MF exposure upon the EEG, ERPs and cognitive and perceptual tasks. We also consider some of the confounding factors within current human MF studies and suggest some new strategies for further experimentation.

The acute effects of exposure to the electromagnetic field emitted by mobile phones on human attention

The aim of our study was to investigate the effects of acute mobile phone exposure on a range of tasks which tapped capacity and processing speed within the attentional system. Thirty-eight healthy volunteers were randomly assigned to either an experimental group which was exposed to a connected mobile phone or a control group in which the mobile phone was switched off. Subjects remained blind to mobile phone status throughout duration of study. The experimental group were exposed to an electromagnetic field emitted by a 900 MHz mobile phone for 30 min. Cognitive performance was assessed at three points (prior to mobile phone exposure, at 15 and 30 min post-exposure) using six cognitive neuropsychological tests (digit span and spatial span forwards and backwards, serial subtraction and verbal fluency). Significant differences between the two groups were evident after 5 min on two tests of attentional capacity (digit span forwards and spatial span backwards) and one of processing speed (serial subtraction). In all three instances, performance was facilitated following mobile phone exposure. No deficits were evident. These findings are discussed in terms of possible functional and neuroanatomical bases.