Norbert Leitgeb

Sensitivity to electricity--temporal changes in Austria.

BackgroundAn increasing number of persons suffer from non-specific health symptoms such as headache, sleep disturbances, difficulties in concentrating and more. In lack of a medical explanation, more and more persons take refuge to the assumption that they were electromagnetic hypersensitive (EHS) and electromagnetic pollution causes their problems. The discussion whether electromagnetic fields (EMF) could cause such adverse health effects is still ongoing.MethodsBased on the Austrian inhabitants a statistical cross-sample of the general population with regard to age, gender and federal state had been investigated to assess the actual situation and potential temporal changes in comparison with a former study of 1994. In a telephone survey a total number of 526 persons were included.ResultsThis study showed an actual EHS prevalence of 3.5% compared with 2% estimated in 1994. About 70% of the sample believed that electromagnetic pollution could be a risk factor for health. More than 30% declared to at least some degree to be concerned about their well-being near mobile phone base stations or power lines. However, only 10% were actively looking for specific information. Media triggered EHS hypothesis in 24% of the cases.ConclusionThe results show that concerns about EMF did not decrease with time in spite of scientific studies and health risk assessments concluding that a causal relationship of EMF below recommended reference levels and non-specific health symptoms would be implausible.

Fetal exposure to low frequency electric and magnetic fields

To investigate the interaction of low frequency electric and magnetic fields with pregnant women and in particular with the fetus, an anatomical voxel model of an 89 kg woman at week 30 of pregnancy was developed. Intracorporal electric current density distributions due to exposure to homogeneous 50 Hz electric and magnetic fields were calculated and results were compared with basic restrictions recommended by ICNIRP guidelines. It could be shown that the basic restriction is met within the central nervous system (CNS) of the mother at exposure to reference level of either electric or magnetic fields. However, within the fetus the basic restriction is considerably exceeded. Revision of reference levels might be necessary.

Vision-based motion detection, analysis and recognition of epileptic seizures-A systematic review

The analysis of human motion from video has been the object of interest for many application areas, these including surveillance, control, biomedical analysis, video annotation etc. This paper addresses the advances within this topic in relation to epilepsy, a domain where human motion is with no doubt one of the most important elements of a patients clinical image. It describes recent achievements in vision-based detection, analysis and recognition of human motion in epilepsy for marker-based and marker-free systems. An overview of motion-characterizing features extracted so far is presented separately. The objective is to gain existing knowledge in this field and set the route marks for the future development of an integrated decision support system for epilepsy diagnosis and disease management based on automated video analysis. This review revealed that the quantification of motion patterns of selected epileptic seizures has been studied thoroughly while the recognition of seizures is currently in its beginnings, but however feasible. Moreover, only a limited set of seizure types have been analyzed so far, indicating that a holistic approach addressing all epileptic syndromes is still missing.

Mobile phones: are children at higher risk?

ZusammenfassungIn den vergangenen Jahren hat die Benutzung von Mobiltelefonen durch Kinder immer mehr zugenommen, wobei der Nutzungsbeginn immer früher erfolgt. Dies führte zu Befürchtungen, dass Kinder einem höheren Risiko ausgesetzt sein könnten und ihnen die Benützung daher sogar verboten werden sollte. Empfehlungen von angesehenen nationalen und internationalen Komitees sind widersprüchlich und daher insgesamt für besorgte Eltern und Ärzte mehr verwirrend als hilfreich, aber dies kann erklärt werden. Es wird gezeigt, dass die unterschiedlichen Meinungen von derselben Datenlage abgeleitet werden und die unterschiedliche Art widerspiegeln, wie mit Unsicherheiten des Wissens umgegangen wird. Nach den Einschätzungen der internationalen Komitees und dem gesicherten Wissen über die Entwicklung von Kindern kann geschlossen werden, dass die bestehenden Grenzwerte einen ausreichenden Schutz gewährleisten. Im Vergleich zu den Erwachsenen sind jedoch Kinder je nach ihrem Alter einem relativ höheren potentiellen Risiko ausgesetzt. Wenn daher Erwachsenen empfohlen wird, ihre Exposition zu minimieren, so ist das für Kinder umso mehr gerechtfertigt. Ein Zirkelschluss muss jedoch vermieden werden: Die in der Ungewissheit begründete Vorsorge darf nicht als Beweis für das Bestehen eines realen Risikos missverstanden werden.SummaryThe use of mobile phones by children has in recent years been increasing, the onset starting earlier and earlier. This has led to concern about whether children might be at higher risk and whether mobile phone use should even be forbidden. Advice from highly reputed committees on both national and international levels is contradictory and on the whole more confusing than helpful to worried parents and physicians, but this can be explained. It is shown here that different opinions derived from the same database reflect the different way in which uncertainty of knowledge is dealt with. Based on the assessments of the international committee and established knowledge on childrens development it can be concluded that existing exposure limits do in fact provide reasonable safety. Compared to adults, however, children do in fact need to be considered at a relatively higher potential risk, depending on their phase of development. If adults are adviced to minimise their exposure, this is even more justified for children. However, circular reasoning must be avoided: the uncertainty-triggered application of precaution must not be misinterpreted as evidence for definite risk.

Does “electromagnetic pollution” cause illness?

SummaryMore and more self-declared electromagnetic hypersensitive patients are entering physicians’ practices seeking help. To assess the prevalence of cases and the opinion of Austrian physicians regarding the potential health-relevance of environmental electromagnetic fields (“electromagnetic pollution”), a statistical investigation among general practitioners was undertaken, with surprising results. Only one-third report on never having been asked about the health impact of electromagnetic pollution by patients. An overwhelming percentage of general practitioners (up to 96%) to some degree, or totally, believe in a health-relevant role of environmental electromagnetic fields, and only 39% have never associated health symptoms with “electromagnetic pollution”. Two-thirds are consulted occasionally or even frequently by self-declared electromagnetic hypersensitive patients. However, sound information seems to be lacking. Knowledge on existing electromagnetic exposure limits and on environmental field levels in relation to them is poor. It is remarkable that authorities play a marginal role in informing physicians. Only 4% mention having received information on “electromagnetic pollution” from such a source. It is rather remarkable that there is such a widespread contradiction between physicians’ opinions and established national and international health risk assessment. With respect to the frequency with which doctors are confronted with this issue, the results demonstrate an urgent need for action.ZusammenfassungImmer mehr von ihrer elektromagnetischen Überempfindlichkeit überzeugte Patienten suchen ärztliche Hilfe. Um das Vorkommen dieser Fälle und die Meinung der österreichischen Ärzte über die potentielle Gesundheitsrelevanz elektromagnetischer Felder im Alltag (Elektrosmog) zu erfassen, wurde eine statistische Untersuchung unter den Allgemeinmedizinern Österreichs durchgeführt, die zu überraschenden Ergebnissen geführt hat. Nur ein Drittel der befragten Ärzte berichtet, niemals von Patienten über die gesundheitliche Bedeutung von Elektrosmog befragt zu werden, zwei Drittel geben an, gelegentlich oder häufig von Patienten konsultiert zu werden, die von ihrer elektromagnetischen Überempfindlichkeit überzeugt sind. Ein überwältigender Prozentsatz von bis zu 96 % schließt einen gesundheitsrelevanten Einfluss von Elektrosmog nicht aus und nur 39 % diagnostizieren niemals einen Zusammenhang zwischen Gesundheitsbeschwerden und Elektrosmog. Allerdings scheint ein großer Informationsmangel zu herrschen. Das Wissen über Elektrosmog, die bestehenden Grenzwerte und die Größe der elektromagnetischen Umgebungsfelder im Vergleich zu ihnen ist gering, und 99 % der Ärzte empfinden die Informationen über elektromagnetische Überempfindlichkeit als nicht ausreichend. Es ist bemerkenswert, dass die Behörden eine marginale Rolle bei der Information spielen. Nur 4 % der Ärzte geben an, von ihnen Informationen über Elektrosmog zu erhalten. Es ist eher einzigartig, dass es einen derartig weit verbreiteten Widerspruch zwischen den Meinungen von Ärzten und der anerkannten nationalen und internationalen Risikobewertung gibt. Angesichts der Häufigkeit der Begegnung mit dieser Thematik zeigen die Ergebnisse einen dringenden Handlungsbedarf auf.

Electric current perception of the general population including children and the elderly

Although the 50 Hz electric current perception threshold is a key parameter for limiting electric touch currents in electrical technology and for limiting indirect effects of external electromagnetic fields, the data available mainly reflect mens perception ability; with only sparse data for women and almost none for children or the elderly. Measurements with 240 children aged 9 – 16 years, and 123 elderly people, allow this gap of knowledge to be filled. Taking into account the demographic age distribution, it was possible to generate a probability distribution representing the perception ability of the overall general population, and thus to provide a more established basis for deriving safety limits. The results show that the existing limit values for electric touch currents are considerably too high if compared with results derived from the new data with the same criteria. On the other hand, it appeared that children do not exhibit such a high sensitivity to electricity as assumed to date. Therefore, former rule-of-thumb estimates to account for higher sensitivities of children lie on the safe side. The presented assessment of the general populations electric current perception ability should stimulate a critical review of the existing regulations.

RF-EMF exposure of fetus and mother during magnetic resonance imaging.

Magnetic resonance imaging (MRI) avoids risks of genetic damage but may be associated with excess heating of body tissues. To investigate the exposure to MRI radio-frequency (RF) electromagnetic fields (EMF), low-pass and high-pass birdcage coils were simulated and the whole-body pregnant woman model SILVY used to determine local and whole-body specific absorption rates (SAR) in mother and fetus. Resonant RF-EMF of MRI devices were investigated at 0.3, 1, 1.5, 2, 3 and 4 T. Results allow extrapolation also to higher fields. They showed that local SAR in mothers trunk reaches exposure limits first. However, data show that during abdominal MRI meeting exposure limits of the mother is not sufficient to protect the fetus if limits of the general populations are applied to it. In that case fetal whole-body SAR exceeds limits by 7.4-fold. It is up to the physician and/or the ethics commission to decide upon justification for abdominal MRI of pregnant women if limits are exceeded. The results indicate the need for specifically addressing fetal exposure to EMF and elaborating general recommendations by radiation protection bodies.

Dosimetric Assessment of Simultaneous Exposure to ELF Electric and Magnetic Fields

In the low-frequency range, both electric and magnetic fields interact with biological tissue by inducing intracorporal electric current densities, although ruled by different physical laws and, hence, with different intracorporal orientation and pathways. Presently, standards require a separate assessment of electric and magnetic fields even in the case of simultaneous exposure and, hence, ignore the superposition of intracorporal current densities. Numerical simulations with the Visible Man model show that this can lead to underestimating current densities in the central nervous system (CNS) by up to 29%. While the superposed electric current densities in the CNS still meet the basic restrictions, the situation changes if a fetus with its own CNS requires the same level of protection. When the compliance volume is extended to the trunk, the reference-level electric-field exposure exceeds the basic restrictions by 38%. Depending on the kind of summation of the vectorial contributions, simultaneous exposure to the 50 Hz-5 kV/m electric field and 100-T magnetic field may lead to a 2.1-fold to 2.6-fold excess of the basic restriction. While this does not prove noncompliance, it indicates that fetal CNS exposure modeling is needed for clarification.

Perception of ELF electromagnetic fields: excitation thresholds and inter-individual variability.

So far, in guidelines limiting exposure to electromagnetic fields, basic limits of intracorporal electric current densities have been recommended to prevent from nerve cell stimulation. They were based on experimental data and extrapolated to the general population with limited knowledge on the inter-individual variability. To assess the variability of cellular excitability the perception thresholds for directly applied electric currents were used as surrogate. However, until recently, the data on perception ability of electric currents were gained from small groups only and led to controversial results, differing by more than one order of magnitude. This paper discusses the results of our previous research comprising extensive measurements on 1,071 individuals (349 men and 359 women aging 16 to 60 y, 117 girls and 123 boys aging 9 to 16 years, and 123 individuals older than 60 y). Their electric current perception thresholds fit fairly well with a log-normal distribution. The electric 50 Hz current perception threshold was measured by directly applied pairs of electrodes at the lower forearms. It was found that the inter-individual variability comprises two orders of magnitudes which is one order of magnitude higher than assumed so far. Women were found to be significantly more sensitive than men. Depending on the level of probability p, the perception threshold for women was 0.77-fold (p = 50%) or even 0.45-fold (p = 0.5%) lower than for men. Surprisingly, children turned out to be considerably more sensitive than men but similar to women. The age dependence exhibited a decrease of perception thresholds with age from adult men to boys joining the values of girls at ages around 10 y. The results indicate that existing safety limits for touch currents need critical review. Apart from the inter-individual variability, it was estimated to which place within the distribution of perception levels the basic limits were related. Therefore, numerical simulations were made to calculate intracorporal electric current densities associated with the applied electric currents. The results confirm that the basic limits of intracorporal electric current densities as recommended by ICNIRP are conservative to prevent cellular excitation.

Electric current perception study challenges electric safety limits

Although a key parameter for safety regulations, the electric current perception threshold is not sufficiently established yet. Present knowledge suffers from a lack of womens data, small numbers of data on investigation of men and investigated samples non-representative for the general population. With measurement at 708 adults aged between 16 and 60 years (349 men and 359 women) these deficiencies could be overcome. The results are important. They show that the perception variability among the general population is 100-fold higher than estimated so far and that the currently used estimate of the threshold is more than 10-fold too high. Besides this, it could be shown that there are an over-proportion of more sensitive women compared with men indicating the need for revision of the present assumptions on gender-specific differences in electrosensibility. The results show that the existing assumptions on safety limits and remaining safety factors need serious review. In any case, relaxation of safety requirements is not justified.