Effects of mobile phone electromagnetic field: behavioral and neurophysiological measurements

Siirretty Doriast

Nonlinear dynamical analysis of brain electrical activity due to exposure to weak environmentally relevant electromagnetic fields

The reports dealing with the effects of weak electromagnetic fields (EMFs) on brain electrical activity have been inconsistent. We suspected that the use of linear models and their associated methods accounted for some of the variability, and we explored the issue by using a novel approach to study the effects of EMFs on the electroencephalogram (EEG) from rabbits and humans. The EEG was embedded in phase space and local recurrence plots were calculated and quantified to permit comparisons between exposed and control epochs from individual subjects. Statistically significant alterations in brain activity were observed in each subject when exposed to weak EMFs, as assessed using each of two recurrence-plot quantifiers. Each result was replicated; a sham exposure control procedure ruled out the possibility that the effect of the field was a product of the method of analysis. No differences were found between exposed and control epochs in any animal when the experiment was repeated after the rabbits had been killed, indicating that a putative interaction between the field and the EEG electrodes could not account for the observed effects. We conclude that EMF transduction resulting in changes in brain electrical activity could be demonstrated consistently using methods derived from nonlinear dynamical systems theory

Effects of mobile phone radiation on the human central nervous system

The effects of mobile phone-like electromagnetic radiation on the human brain activity are examined. The research focuses on both radio frequency (RF) exposures and the much less studied low frequency (ELF) exposures (less than 40 kHz) arising from the battery operation of GSM handsets. The first single blind study recruited a small sample of twelve human volunteers. The eyes closed resting EEG activity is monitored after radio frequency exposure. With SAR levels of 2 W/kg, results reveal no statistical changes in any of the examined frequency bands for neither pulsed modulated RF signals nor continuous wave RF signals. In the second double blind study, a sample of 72 volunteers is recruited and an improved protocol comprised of separate pulsed RF, continuous RF and pulsed ELF exposures is employed. Exposures are delivered through a custom made handset capable of independent RF and ELF exposures. Findings include a reduced alpha band frequency activity during pulsed radio frequency and low frequency radiations exposures but no changes under the continuous RF radiation. Changes are present both during as well as after exposure, while greater changes are observed during exposures. The study of some non linear measures of the resting EEG revealed no changes under any of the active exposures. As the observed changes are very close to the normal EEG variation during resting conditions, their biological significance and health impact is not immediately obvious. However, their mere demonstration points to a low level interaction mechanism which may deserve further study

Influence of mobile phone electromagnetic field exposures on nervous function in the human brain and heart

This thesis aims to determine whether RF pulsed exposures from mobile phones can influence nervous function within the human brain and heart. In order to address this objective, a robust double-blind study to investigate mobile phone exposures on nervous response has been undertaken by means of analysis of electrophysiological test measures of brain wave activity and heart responses. Generally, test measurements of the electroencephalogram (EEG), the electrocardiogram (ECG), and the pulse plethysmogram (PPG) (for indications of blood pressure response) have been undertaken whilst participants are exposed and sham exposed to various GSM mobile phone radiofrequency and low-frequency protocols. In initial work, both standby and full-power mode GSM exposures have been investigated (Chapter 3 - EEG investigated only), while pulsed 900 MHz and 1800 MHz continuous wave exposures have been investigated in the final experimental work involving 100 test participants (Chapter 8 - EEG, ECG, and PPG measures are inves tigated). Four predominant outcomes are determined from the final experimental work conducted. These main outcomes specifically include: 1. A new 'characteristic' finding in the EEG alpha band (8-13 Hz) as due to 900 MHz exposures is observed from almost all recording sites, over both brain hemispheres. Notably, this response only appears at 900 MHz, though is not observable for the 1800 MHz exposure; 2. An EEG effect due to both pulsed 900 MHz and 1800 MHz exposures notably appearing at 16 Hz is a new critical finding and is observed across both hemispheres. Most importantly, at this beta rhythm only a decreasing tendency in EEG power can be noted for the 900 MHz exposure tested but only an increasing tendency in EEG power may be noted at 1800 MHz, suggesting that the direction of the effect in EEG power may be dependent on the RF component; 3. Effects at 900 MHz on the contralateral side to exposure at central, temporal, and parietal sites appear to indicate a common median difference response between sham and exposure EEG spectral power density, which does not appear on the ipsilateral side to exposure; 4. As consistent with most previously published research, 900 MHz or 1800 MHz exposures pulsed at 217 Hz do not appear to alter heart rate, heart rate variability (HRV), or blood pressure variability (BPV). To reduce confounding factors and errors in experimental results, several novel approaches were developed as described (Chapters 4 - 8). These approaches include the development and testing of an experimental handset to support multiple mobile phone signals, a comparative analysis of 900 MHz and 1800 MHz exposures (near the health protection limits) on the same group of participants in simultaneous experiments, development of a statistical analysis approach to EEG that addresses both type 1 and type 11 errors at high resolution, and quantification of potential effects of EEG recording leads on SAR and electric field distribution (at both 900 MHz and 1800 MHz) inside a SAM phantom and realistic computational head model. Outcomes of this research address forefront international health concerns regarding almost 2-billion mobile phone users worldwide

The effects of cultural influences and personal state on electrodermal orienting responses to phobic stimuli

Seligman's theory that phobias are biologically prepared associations is challenged on theoretical and empirical grounds. It is argued that a concept of experiential preparedness may be more useful for approaching the problem of selectivity in phobias. The experimental part of the thesis pursues this argument by investigating the magnitude and habituation of electrodermal orienting responses (ORs) to words denoting ontogenetically fear-relevant (phobic) or neutral stimuli. In experiment 1 no differences between the ORs to moderately feared and neutral stimuli were found. In experiment 2 subjects were presented with stimuli as in experiment 1 and were threatened by electric shock; the phobic stimuli then elicited larger and more slowly habituating ORs than the neutral stimuli. In the following three experiments, subjects were presented with stimuli they reported as not feared but of which the majority of their peers reported substantial fears. In experiment 3 there was no manipulation of the state of the subject, in experiment 4 subjects were under threat of shock, and in experiment 5 they anticipated pleasant music. Only in experiment 4 did subjects show larger and more slowly habituating ORs to phobic than neutral stimuli. In the last two experiments, pleasant stimuli were administered while subjects anticipated shock or music. On the whole, no differences in ORs to pleasant and neutral stimuli were found under either of the two conditions. The results suggest that the OR is not simply linked to the detection of stimulus change or significance and depends on the state of the subject, with stimuli known to be associated with fear taking precedence in processing when subjects anticipate threat. As phobias are assumed to be learned responses and the OR has important implications for learning it is concluded that phobic responses towards stimuli feared in the culture may be formed when people perceive the future as threatening and unpredictable.<p

Muscle activation patterns in shoulder impingement patients

Introduction: Shoulder impingement is one of the most common presentations of shoulder joint problems 1. It appears to be caused by a reduction in the sub-acromial space as the humerus abducts between 60o -120o – the 'painful arc'. Structures between the humeral head and the acromion are thus pinched causing pain and further pathology 2. Shoulder muscle activity can influence this joint space but it is unclear whether this is a cause or effect in impingement patients. This study aimed to observe muscle activation patterns in normal and impingement shoulder patients and determine if there were any significant differences. Method: 19 adult subjects were asked to perform shoulder abduction in their symptomatic arm and non-symptomatic. 10 of these subjects (age 47.9 ± 11.2) were screened for shoulder impingement, and 9 subjects (age 38.9 ± 14.3) had no history of shoulder pathology. Surface EMG was used to collect data for 6 shoulder muscles (Upper, middle and lower trapezius, serratus anterior, infraspinatus, middle deltoids) which was then filtered and fully rectified. Subjects performed 3 smooth unilateral abduction movements at a cadence of 16 beats of a metronome set at 60bpm, and the mean of their results was recorded. T-tests were used to indicate any statistical significance in the data sets. Significance was set at P<0.05. Results: There was a significant difference in muscle activation with serratus anterior in particular showing a very low level of activation throughout the range when compared to normal shoulder activation patterns (<30%). Middle deltoid recruitment was significantly reduced between 60-90o in the impingement group (30:58%).Trends were noted in other muscles with upper trapezius and infraspinatus activating more rapidly and erratically (63:25%; 60:27% respectively), and lower trapezius with less recruitment (13:30%) in the patient group, although these did not quite reach significance. Conclusion: There appears to be some interesting alterations in muscle recruitment patterns in impingement shoulder patients when compared against their own unaffected shoulders and the control group. In particular changes in scapula control (serratus anterior and trapezius) and lateral rotation (infraspinatus), which have direct influence on the sub-acromial space, should be noted. It is still not clear whether these alterations are causative or reactionary, but this finding gives a clear indication to the importance of addressing muscle reeducation as part of a rehabilitation programme in shoulder impingement patients