SAR-Werte von Mobiltelefonen

The specific absorption rate (SAR) is a prominent topic in the discussion about precautionary health protection. An experimental study investigated the effect of information about various SAR values (below the existing partial body limit value of 2 W/kg) on safety judgments of potential mobile phones users. It turns out that about 94% of the participants do not know the SAR value of their own mobile phone. SAR values below existing limits are not perceived as equally safe. Rather, the lower the SAR value, the higher the perceived safety. However, a majority of the participants does not consider these SAR values to be 100% safe, even if they are clearly below the existing limits. Explicitly indicating a precautionary limit value (referring to the Federal Office for Radiation Protection or to consumer organizations) does not change this safety evaluation. As expected, safety evaluation of the SAR values is also related to the perception of mobile phone risks. Those who are concerned about mobile phone communication give lower safety judgments than the unconcerned-independent of the level of the SAR values. Irrespective of that, our results suggest that establishing the SAR value as a criterion for mobile phones depends first of all on making it known to the public.     

Proposed revision of the Canadian recommendations on radiofrequency-exposure protection

In 1979, the Canadian Federal Government published a safety code which recommended limits of exposure to radiofrequency radiation at frequencies from 10 MHz to 300 GHz. This paper outlines and discusses proposed revisions to these recommendations. The main changes include an extension of the frequency range down to 10 kHz, a change in the exposure limits for the general public, and added recommendations on limiting body current upon contact with ungrounded objects. The rationale for the proposed limits refers to recent data on dosimetry and biological effects, and includes comparison with other national and international standards for radiofrequency exposure protection.     

A suggested limit for population exposure to radiofrequency radiation

Unlike a number of other nations, the U.S. does not currently have guidelines for the exposure of the public to radiofrequency (RF) radiation. In order to determine whether the current data base was sufficient to support an interim determination of a limit for population exposure to RF radiation (0.5 MHz-100 GHz), a critical and comprehensive review of the available literature on the biological effects of RF radiation was recently completed. In the analysis of this data, a number of simplifying assumptions had to be employed; among them was the use of the specific absorption rate (SAR) as the mass-normalized, frequency-independent measure of RF energy input into biological systems. The biological effects reported in acceptable studies were assessed in terms of their associations with (1) core temperature increases, (2) SAR, (3) SAR as a percentage increase over resting metabolic rate, and (4) direct evidence for human effects. Based on information now available and analyzed from these four perspectives, a conservative SAR threshold value of approx. 0.4 W/kg is apparent. Since the unknowns and uncertainties are potentially significant, one might consider, from the standpoint of prudence, the further application of a safety factor of 10. Given the present state of knowledge, the resultant SAR limit of 0.04 W/kg is, in the author's opinion, unlikely to be associated with the adverse health effects in the general population. This SAR translates into a power density of approximately 200 mu W/cm2 in the human resonant frequency range of 30-300 MHz.     

Characterization of personal RF electromagnetic field exposure and actual absorption for the general public

In this paper, personal electromagnetic field exposure of the general public due to 12 different radiofrequency sources is characterized. Twenty-eight different realistic exposure scenarios based upon time, environment, activity, and location have been defined and a relevant number of measurements were performed with a personal exposure meter. Indoor exposure in office environments can be higher than outdoor exposure: 95th percentiles of field values due to WiFi ranged from 0.36 to 0.58 V m(-1), and for DECT values of 0.33 V m(-1) were measured. The downlink signals of GSM and DCS caused the highest outdoor exposures up to 0.52 V m(-1). The highest total field exposure occurred for mobile scenarios (inside a train or bus) from uplink signals of GSM and DCS (e.g., mobile phones) due to changing environmental conditions, handovers, and higher required transmitted signals from mobile phones due to penetration through windows while moving. A method to relate the exposure to the actual whole-body absorption in the human body is proposed. An application is shown where the actual absorption in a human body model due to a GSM downlink signal is determined. Fiftieth, 95th, and 99 th percentiles of the whole-body specific absorption rate (SAR) due to this GSM signal of 0.58 microW kg(-1), 2.08 microW kg(-1), and 5.01 microW kg(-1) are obtained for a 95th percentile of 0.26 V m(-1). A practical usable function is proposed for the relation between the whole-body SAR and the electric fields. The methodology of this paper enables epidemiological studies to make an analysis in combination with both electric field and actual whole-body SAR values and to compare exposure with basic restrictions.     

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.     

IEEE Committee on Man and Radiation (COMAR) Technical Information Statement "exposure of medical personnel to electromagnetic fields from open magnetic resonance imaging systems"

Open magnetic resonance imaging (MRI) systems enable performing image-guided medical procedures for long periods of time very close to, or inside, the patient imaging area. Medical personnel can be exposed to relatively high static, gradient, and radiofrequency fields compared to most other MRI systems. The Committee on Man and Radiation of the Institute of Electrical and Electronics Engineers calculated or used existing data on magnetic flux densities and field strengths in or near the patient area to assess occupational exposure levels. Potential exposures to each field type were analyzed and compared to relevant values specified in international exposure limits including those of the Institute of Electrical and Electronics Engineers and the International Commission on Nonionizing Radiation Protection. Exposures of the head or torso of a worker to gradient fields near the center of the patient-imaging area can exceed most exposure limits even for times less than a second. Exposures to radiofrequency fields can exceed limits if sustained exposures (minutes or more) occur to parts of the body. Static magnetic fields used by present Open MRI systems are below exposure limits of all of the standards that address these fields. Overall results of this study suggest that manufacturers and others who program or operate Open MRI systems should take care to ensure that operating parameters produce exposures that comply with the relevant exposure limits. Also, since field levels fall off rapidly with increasing distance, user practices may be implemented that reduce exposures significantly.     

Occupational exposure to radiofrequency electromagnetic fields

High exposures to radiofrequency electromagnetic fields (RF EMF) are possible in workplaces involving sources used for broadcasting, telecommunication, security and identification, remote sensing and the heating and drying of goods. A systematic literature review of occupational RF EMF exposure measurements could help to clarify where more attention to occupational safety may be needed. This review identifies specific sources of occupational RF EMF exposure and compares the published maximum exposures to occupational exposure limits. A systematic search for peer-reviewed publications was conducted via PubMed and Scopus. Relevant grey literature was collected via web searches. For each publication, the highest measured electric field strength, magnetic flux density or power density was extracted. Maximum exposures exceeding the limits were reported for dielectric heating, scanners for security and radiofrequency identification, plasma devices and broadcasting and telecommunication transmitters. Occupational exposure exceeding the limits was rare for microwave heating and radar applications. Some publications concerned cases studies of occupational accidents followed by a medical investigation of thermal health effects. These were found for broadcasting antennas, radar installations and a microwave oven and often involved maintenance personnel. New sources of occupational exposure such as those in fifth generation telecommunication systems or energy transition will require further assessment.     

A tale of two limits

As they do with other potentially hazardous agents, occupational health and safety professionals in the United States take a two-pronged approach to controlling noise exposure. We assure compliance with OSHA's regulatory limits to satisfy lawyers and compliance officers while using TLVs to protect worker health. Unfortunately, using both the TLV and OSHA limits for noise exposure may involve considerably more work than for most chemical exposures. Using both limits for noise may require different measuring equipment or multiple measurements of exposure. Using the TLV also may require noise measurement at the abdomen, as well as the ear and consideration of concomitant chemical exposures. Finally, using the TLV requires the OHS professional to confront the fact that no exposure value can claim to protect all workers and that employee rotation may result in more hearing loss than would exposing a smaller group of workers to more noise. These facts make it clear why OHS professionals should never use exposure limits as just numbers. Rather, we strive to understand the basis for the limits we are using, to be sure we understand the limitations of those limits and how they might uniquely affect our workers in their work environments.     

Effect of a 2.45-GHz radiofrequency electromagnetic field on neutrophil chemotaxis and phagocytosis in differentiated human HL-60 cells

The potential public health risks of radiofrequency (RF) fields have been discussed at length, especially with the use of mobile phones spreading extensively throughout the world. In order to investigate the properties of RF fields, we examined the effect of 2.45-GHz RF fields at the specific absorption rate (SAR) of 2 and 10 W/kg for 4 and 24 h on neutrophil chemotaxis and phagocytosis in differentiated human HL-60 cells. Neutrophil chemotaxis was not affected by RF-field exposure, and subsequent phagocytosis was not affected either compared with that under sham exposure conditions. These studies demonstrated an initial immune response in the human body exposed to 2.45-GHz RF fields at the SAR of 2 W/kg, which is the maximum value recommended by the International Commission for Non-Ionizing Radiation Protection (ICNIRP) guidelines. The results of our experiments for RF-field exposure at an SAR under 10 W/kg showed very little or no effects on either chemotaxis or phagocytosis in neutrophil-like human HL-60 cells.     

Radio frequency radiation exposure standards: considerations for harmonization

Radio frequency radiation exposure standards vary in origin, development process, legal status, and in the actual exposure limits. To identify the sources of differences in limits, we evaluated technical aspects of eight standards that included supporting information on the scientific data and rationale. Comparisons were made among the standards by examining the scope of the underlying database, the rationales for safety factors and other issues underlying exposure limits in the energy-deposition range (0.1 MHz to 10.0 GHz) and in the surface-heating range (about 10 or 15 GHz to 300 GHz). The framework for this assessment was based on the methods recommended by the scientific and regulatory organizations for developing health-based exposure limits. General guidelines for performing risk assessments for threshold acting agents have been developed by the U.S. Environmental Protection Agency, Health Canada's Environmental Health Directorate, and the International Program on Chemical Safety of the World Health Organization. This general methodology was applied to radiofrequency radiation for this assessment. Because these methods strive to identify scientific issues and separate them from risk management or policy, they provide a basis for evaluation of standards in this paper. This distinction can provide a foundation for the longer-term goal of global harmonization of radio frequency radiation standards. Each of the standards evaluated in the energy-deposition range was found to use the same basic restriction, based on biological data and a 10-fold safety factor, yet explanations reflect different interpretations of the underlying biological data. Rationales differ for the magnitude of the safety factor, for the circumstances of exposure, for the nature of sensitive populations, and for the presumed health status of the individuals for whom the basic restriction is applicable. In the surface-heating range, broad variability in exposure limits are seen in the limit itself, as well as in the approach to time averaging and frequency dependence. Averaging times differ among standards, as do tissue geometries for defining partial-body exposures. The differences in approaches to develop the standards do not completely explain differences among the exposure limits, and methods for computing exposure limits from basic restrictions are not always defined. This analysis suggests harmonization of standards will require more detailed review and coordination of biological and engineering data and of policy options.     

Health implications of exposure to radiofrequency/microwave energies

ABSTRACT The rapid development of and the increase in the number and variety of devices that emit microwave/radiofrequency (MW/RF) energies has resulted in a growing interest regarding the potential effects on health of these energies. The frequency ranges considered in this review are: 300 kHz to 300 MHz (radiofrequency) and 300 MHz to 300 GHz (microwaves). Investigations have shown that exposure to certain power densities for several minutes or hours can result in pathophysiological manifestations in laboratory animals. Such effects may or may not be characterised by a measurable rise in temperature, which is a function of thermal regulatory processes and active adaptation by the animal. The end result is either a reversible or irreversible change, depending on the irradiation conditions and the physiological state of the animal. At lower power densities, evidence of pathological changes or physiological alteration is non-existent or equivocal. Much discussion, nevertheless, has taken place on the relative importance of thermal or non-thermal effects of radiofrequency and microwave radiation. Several retrospective studies have been done on human populations exposed or believed to have been exposed to MW/RF energies. Those performed in the US have not shown any relationship of altered morbidity or mortality to MW/RF exposure. Reactions referrable to the central nervous system and cardiovascular effects from exposure of man to microwave energy have been reported mostly in Eastern European publications. Individuals suffering from various ailments or psychological factors may exhibit the same dysfunctions of the central nervous and cardiovascular systems as those reported to result from exposure to MW/RF; thus it is extremely difficult, if not impossible, to rule out other factors in attempting to relate MW/RF exposure to clinical conditions. There is a need to set limits on the amount of exposure to MW/RF energies that individuals can accept with safety. Operative protection standards have apparently provided adequate safety to workers and the general population to permit the use of MW/RF energies without harm or detriment.     

Use of hardware modified phones for exposure assessment in health studies in Australia: verification of compliance with standards

Most epidemiological studies investigating health effects of mobile telephone use have been criticised for poor quality of exposure assessment. Most used questionnaires which have limited precision to assess exposure. Clearly more relevant and direct methods of exposure assessment are needed. We describe the calibration of hardware modified phones (HMPs) for exposure assessment and dosimetry and verified their compliance with Australian and international standards. Specific energy absorption rate (SAR) values at various tilts and rotations and their combinations were obtained for the HMPs using a ‘DASY3’ SAR measuring system. Calibration involved placing HMPs on human head phantoms and taking measurements at 900 and 1800 MHz bands on right and left sides of the phantom. At 900MHz the maximum SAR obtained with HMPs at the touch position was 0.9W/kg and 0.4W/kg at 30 degrees tilt but at 1800MHz, SAR at the touch and 30 degrees tilts were 1.1W/kg and 1.3W/kg respectively. Whilst tilt and rotation each had an effect on SAR at constant frequency, no interaction was observed with rotation and frequency, however one was observed between tilt and frequency. At 1800 MHz mean SAR at 30 degrees tilt was 0.22W/kg higher (95% CI 0.15, 0.30) than at 0 degrees, whereas at 900 MHz mean SAR at 30 degrees tilt was 0.60W/kg lower (95% CI 0.52, 0.67) than at 0 degrees. Our results indicated that tilts influence SAR more than rotations. SAR values obtained at both 900/1800 MHz for the HMPs were well below ICNIRP limits for the general public. The phones were compliant with both international and Australian standards.     

Medical aspects of radiofrequency radiation overexposure

Despite seemingly widespread concerns about radiofrequency radiation overexposure to the general population, there is very little in the medical literature that addresses this issue. This article is written by a consensus-forming body composed of physicians, biologists, engineers, and physical scientists. It addresses those aspects of radiofrequency radiation exposure that are pertinent to clinical medicine. It is intended to provide basic information on radiofrequency radiation injuries to be helpful to physicians should they ever be presented with a patient who was overexposed to radiofrequency radiation. Salient features of radiofrequency radiation physics, radiofrequency radiation injuries, and national safety standards are discussed. A synopsis of the signs and symptoms of radiofrequency radiation overexposure and a statement concerning the role of a physician are also included. This Note is intended to update practitioners on the best available information on radiofrequency radiation exposure management and the results of recent national and international standard setting activities.     

Drinking water,diet, indoor air: Comparison of the contribution to environmental micropollutants exposure

This study collated 254,441 analytical results from drinking water quality monitoring in order to compare levels of exposure of the French adult population from drinking water with that from total diet for 37 pesticides, 11 mineral elements, 11 polycyclic aromatic hydrocarbons (PAH), 6 non dioxin-like polychlorobiphenyls (NDL PCB), 5 ether polybromodiphenyl ethers (BDE), 2 perfluorinated compounds. It also compares levels of exposure from drinking water with that from inhalation of indoor air for 9 volatile organic compounds (VOC) and 3 phthalates. The vast majority of the water analysis results showed values below the limits of quantification and this comparison was primarily made on the basis of a highly pessimistic scenario consisting in considering the data below the limits of quantification as being equal to the limits of quantification. With this conservative scenario, it can be seen that tap water makes a minor but potentially non-negligible contribution for a few micropollutants, by comparison with diet and air. It also shows that exposure through drinking water remains below the toxicity reference values for these substances. Apart from a few extreme values reflecting exceptional local situations, the concentrations measured for the minority of positive samples (below the 95th percentile value) suggest a very low risk for human health. Lower limits of quantification would however be of use in better estimating the safety margin with regard to the toxicity reference values, in particular for BDE, PAH and NDL PCB.     

Estimates of absorption of radiofrequency radiation by the embryo and fetus during pregnancy.

This paper reports that the specific absorption rate induced in the embryo or fetus can exceed that recommended for the general public when the mother is exposed to radiofrequency radiation at the occupational limits. This result applies to two-tiered radiofrequency radiation standards where a factor of 5 differentiates occupational and nonoccupational exposure limits. Using simple axisymmetric geometries for the pregnant worker, and assuming plane wave exposures, a finite element method provides estimates of prenatal exposure. Various layered shapes are used to model skin, fat, uterus, blood, embryonic, and fetal tissues. Applying current exposure limits given by IRPA, ANSI, and SAA, the results indicate that overexposures to the embryo or fetus can occur from early pregnancy at 80-100 MHz, and in late pregnancy across the range 300-1500 MHz.     

Comparison of the effects of continuous and pulsed mobile phone like RF exposure on the human EEG

It is not clear yet whether Global System for Mobiles (GSM) mobile phone radiation has the ability to interfere with normal resting brain function. There have been reports that GSM exposure increases alpha band power, and does so only when the signal is modulated at low frequencies (Huber, R., Treyer, V., Borbely, A. A., Schuderer, J., Gottselig, J. M., Landolt, H.P., Werth, E., Berthold,T., Kuster, N., Buck, A and Achermann, P. Electromagnetic fields, such as those from mobile phones, alter regional cerebral blood flow and sleep and waking EEG. J Sleep Res 11, 289-295, 2002.) However, as that research employed exposure distributions that are not typical of normal GSM handset usage (deep brain areas were overexposed), it remains to be determined whether a similar result patterning would arise from a more representative exposure. In this fully counterbalanced cross-over design, we recruited 12 participants and tried to replicate the modulation linked post exposure alpha band power increase described above, but with an exposure source (dipole antenna) more closely resembling that of a real GSM handset. Exposures lasted for 15 minutes. No changes to alpha power were found for either modulated or unmodulated radiofrequency fields, and thus we failed to replicate the above results. Possible reasons for this failure to replicate are discussed, with the main reason argued to be the lower and more representative exposure distribution employed in the present study. In addition we investigated the possible GSM exposure related effects on the non-linear features of the resting electroencephalogram using the Approximate Entropy (ApEn) method of analysis. Again, no effect was demonstrated for either modulated or unmodulated radiofrequency exposures.     

1800 MHz射频电磁场对人乳腺癌细胞蛋白质表达的影响

目的采用高通量的蛋白质组学技术研究人乳腺癌细胞株MCF-7细胞受GSM 1800MHz射频电磁场辐照后,其蛋白质表达谱的变化,以探索移动电话信号对细胞正常生理功能的可能影响。方法比吸收率为3．5W／kg时,采用不同时间（1、3、6、12和24h）和辐照模式（间断辐射和连续辐射）的GSM 1800MHz射频电磁场处理MCF-7细胞后,直接抽提蛋白质,然后进行双向凝胶电泳。凝胶经银染后,使用PDQuest软件分析假辐照组与电磁场辐照组间的差异表达蛋白质斑点。每个实验重复3次。结果凝胶上平均可检测到1100个蛋白斑点。3．5W／kg连续辐射6h未发现差异点,其他暴露情况下均可检测到不同数量的差异蛋白,以3．5W／kg间断辐射3h和连续辐照12h检测的差异蛋白点较多,分别为18个和7个。通过搜索SWISS-PROT蛋白数据库,对差异蛋白的类别和功能进行了初步推测,结果表明差异蛋白主要与生物分子的合成和调控、信号转导、DNA损伤修复等功能相关。结论GSM 1800MHz射频电磁场对MCF-7细胞蛋白质表达谱具有一定程度的影响,且依赖于暴露的强度、时间和模式,影响环节可能涉及多个生物学过程。     

Using measurement error models to assess effects of prenatal and postnatal methylmercury exposure in the Seychelles Child Development Study

Studies of the effects of environmental exposures on human health typically require estimation of both exposure and outcome. Standard methods for the assessment of the association between exposure and outcome include multiple linear regression analysis, which assumes that the outcome variable is observed with error, while the levels of exposure and other explanatory variables are measured with complete accuracy, so that there is no deviation of the measured from the actual value. The term measurement error in this discussion refers to the difference between the actual or true level and the value that is actually observed. In the investigations of the effects of prenatal methylmercury (MeHg) exposure from fish consumption on child development, the only way to obtain a true exposure level (producing the toxic effect) is to ascertain the concentration in fetal brain, which is not possible. As is often the case in studies of environmental exposures, the measured exposure level is a biomarker, such as the average maternal hair level during gestation. Measurement of hair mercury is widely used as a biological indicator for exposure to MeHg and is the only indicator that has been calibrated against the target tissue, the developing brain. Variability between the measured and the true values in explanatory variables in a multiple regression analysis can produce bias, leading to either over or underestimation of regression parameters (slopes). Fortunately, statistical methods known as measurement error models (MEM) are available to account for measurement errors in explanatory variables in multiple regression analysis, and these methods can provide an (either "unbiased" or "bias-corrected") estimate of the unknown outcome/exposure relationship. In this paper, we illustrate MEM analysis by reanalyzing data from the 5.5-year test battery in the Seychelles Child Development Study, a longitudinal study of prenatal exposure to MeHg from maternal consumption of a diet high in fish. The use of the MEM approach was made possible by the existence of independent, calibration data on the magnitude of the variability of the measurement error deviations for the biomarker of prenatal exposure used in this study, the maternal hair level. Our reanalysis indicated that adjustment for measurement errors in explanatory variables had no appreciable effect on the original results.     

Effects of continuous low-level exposure to radiofrequency radiation on intrauterine development in rats

To assess the effect of low-level radiofrequency radiation on pregnant rats, gravid dams were exposed continuously to 0.1 mW cm-2 at 27.12 MHz during different periods of pregnancy. Biological assays consisted of determining pre- and post-implantation losses and the effects on maternal body weight increase. Fetal parameters monitored included sex, mean viable fetal weight on Day 20 of gestation, external, skeletal and visceral fetal malformations, anomalies and variations. Dosimetric evaluations were made in terms of average specific absorption rate (SAR) and basal metabolic rate (BMR). Findings included a considerable increase in the percentage of total resorptions, reduced body weight increase in the exposed dams and incomplete cranial ossification in their fetuses. Results obtained were compared with those shown by other authors. It seems possible to ascribe some of the effects to a specific action of the radiofrequency radiation occurring independently of the rise in temperature. The hypothesis the exposure time, together with SAR, plays an important role in inducing specific exposure effects due to radiofrequency radiation is presented.