Fourteen new papers on electromagnetic fields and biology or health (sent via Email on 25 January 2017 to the CHE-EMF working group by Joel M. Moskowitz, Ph.D., Director, Center for Family and Community Health, School of Public Health, University of California, Berkeley).
Fourteen new papers on electromagnetic fields and biology or health
Electromagnetic Radiation Safety, Jan 24, 2017
A follow-up study of the association between mobile phone use and symptoms of ill health
Cho YM, Lim HJ, Jang H, Kim K, Choi JW, Shin C, Lee SK, Kwon JH, Kim N. A follow-up study of the association between mobile phone use and symptoms of ill health. Environ Health Toxicol. 2016 Dec 29. doi: 10.5620/eht.e2017001. [Epub ahead of print]
Objectives: The duration and frequency of mobile phone calls, and their relationship with various health effects, have been investigated in our previous cross-sectional study. This two-year period follow-up study after aimed to assess the changes in these variables of same subjects.
Methods: The study population comprised 532 non-patient adult subjects sampled from the Korean Genome Epidemiology Study. The subjects underwent a medical examination at a hospital in 2012/2013 and revisited the same hospital in 2014/2015 to have the same examination for the characteristics of mobile phone use performed. In addition, to evaluate the effects on health, the Headache Impact Test-6 (HIT-6), Psychosocial Well-being Index-Short Form (PWI-SF), Beck Depression Inventory (BDI), Korean-Instrumental Activities of Daily Living (K-IADL), Perceived Stress Scale (PSS), Pittsburgh Sleep Quality Index (PSQI), and 12-Item Short Form Health Survey (SF-12) were analyzed. For all these tests, the higher the score, the greater the effect on health. Variances between scores in all the indices in the baseline and follow-up surveys were calculated, and correlations of each index were analyzed.
Results: The average duration per call and HIT-6 score of the subjects decreased significantly compared with those recorded two years ago. The results showed a slight but significant correlation between call duration changes and HIT-6 score changes for female subjects, but not for males. HIT-6 scores in the follow-up survey significantly decreased compared to those in the baseline survey, but long-time call users (subjects whose call duration was ≥5 min in both the baseline and follow-up surveys) had no statistically significant reduction in HIT-6 scores.
Conclusion: This study suggests that increased call duration is a greater risk factor for increases in headache than any other type of adverse health effect, and that this effect can be chronic.
Symptoms and the use of wireless communication devices: A prospective cohort study in Swiss adolescents
Schoeni A, Roser K, Röösli M. Symptoms and the use of wireless communication devices: A prospective cohort study in Swiss adolescents.Environ Res. 2017 Jan 20;154:275-283. doi: 10.1016/j.envres.2017.01.004. [Epub ahead of print]
BACKGROUND: We investigated whether radiofrequency electromagnetic fields (RF-EMF) from mobile phones and other wireless devices or by the wireless device use itself due to non-radiation related factors in that context are associated with an increase in health symptom reports of adolescents in Central Switzerland.
METHODS: In a prospective cohort study, 439 study participants (participation rate: 36.8%) aged 12-17 years, completed questionnaires about their mobile and cordless phone use, their self-reported symptoms and possible confounding factors at baseline (2012/2013) and one year later(2013/2014). Operator recorded mobile phone data was obtained for a subgroup of 234 adolescents. RF-EMF dose measures considering various factors affecting RF-EMF exposure were computed for the brain and the whole body. Data were analysed using a mixed-logistic cross-sectional model and a cohort approach, where we investigated whether cumulative dose over one year was related to a new onset of a symptom between baseline and follow-up. All analyses were adjusted for relevant confounders.
RESULTS: Participation rate in the follow-up was 97% (425 participants). In both analyses, cross-sectional and cohort, various symptoms tended to be mostly associated with usage measures that are only marginally related to RF-EMF exposure such as the number of text messages sent per day (e.g. tiredness: OR:1.81; 95%CI:1.20-2.74 for cross-sectional analyses and OR:1.87; 95%CI:1.04-3.38 for cohort analyses). Outcomes were generally less strongly or not associated with mobile phone call duration and RF-EMF dose measures.
CONCLUSIONS: Stronger associations between symptoms of ill health and wireless communication device use than for RF-EMF dose measures were observed. Such a result pattern does not support a causal association between RF-EMF exposure and health symptoms of adolescents but rather suggests that other aspects of extensive media use are related to symptoms.
Exposure to Radiofrequency Electromagnetic Fields From Wi-Fi in Australian Schools
Karipidis K, Henderson S, Wijayasinghe D, Tjong L, Tinker R.Exposure to Radiofrequency Electromagnetic Fields From Wi-Fi in Australian Schools.Radiat Prot Dosimetry. 2017 Jan 10. doi: 10.1093/rpd/ncw370. [Epub ahead of print]
Note: Typical and peak RF levels were found to be lower than ICNIRP guidelines. However, many researchers believe that the guidelines are inadequate to ensure safety. Furthermore,peak RF levels were averaged over 1 minute which is much too long as very short-term intense pulses may have biologic effects.
The increasing use of Wi-Fi in schools and other places has given rise to public concern that the radiofrequency (RF) electromagnetic fields from Wi-Fi have the potential to adversely affect children. The current study measured typical and peak RF levels from Wi-Fi and other sources in 23 schools in Australia. All of the RF measurements were much lower than the reference levels recommended by international guidelines for protection against established health effects. The typical and peak RF levels from Wi-Fi in locations occupied by children in the classroom were of the order of 10-4 and 10-2% of the exposure guidelines, respectively. Typical RF levels in the classroom were similar between Wi-Fi and radio but higher than other sources. In the schoolyard typical RF levels were higher for radio, TV and mobile phone base stations compared to Wi-Fi. The results of this study showed that the typical RF exposure of children from Wi-Fi at school is very low and comparable or lower to other sources in the environment.
Open Access Paper: http://rpd.oxfordjournals.org/content/early/2017/01/10/rpd.ncw370.long
Wi-Fi in Schools & Other Public PlacesRecent Research on WiFi Effects
Monitoring of RF/Microwave field strength at schools in a pilot district in Samsun/Turkey
Çetin Kurnaz, Begüm Korunur Engiz, Murat Cem Bozkurt. Monitoring of RF/Microwave field strength at schools in a pilot district in Samsun/Turkey. Microwave Symposium (MMS), 2016 16th Mediterranean. 14-16 Nov 2016.
As a result of the growing usage of wireless devices and a large number of WLANs installations at schools; determining the exposure levels to students and staff from these systems has become more crucial than before. Since microwave radio links are used to provide connection between wireless devices, proper assessment of exposure to microwave emissions must be carried out. For this reason, in this study electromagnetic radiation (EMR) measurements were conducted at 92 different schools in Ilkadim district twice in 2016 using PMM 8053 EMR meter. The changes in and statistical properties of electric field strengths (E) are determined on the basis of these measurements. The maximum Es (Emax) are 5.39 V/m and 3.04 V/m for each measurement while the maximum average Es (Eavg) are 2.22 and 2.25 V/m. Even though the measured E levels are below the limits that are determined by the International Commission on Non-Ionizing Radiation Protection (ICNIRP); for providing a wide margin of protection and evaluating the health risks they may cause, regular control/measurement of exposed EMR levels is recommended.
[Note: The paper did not discuss the extent Wi-Fi was used in these schools. WLAN was found to emit 0.024 V/m on average.]
RF exposure survey of children and adults: First results from Slovenia
Gajšek P, Struchen B, Valič B. RF exposure survey of children and adults: First results from Slovenia. IEEE Radio and Antenna Days of the Indian Ocean (RADIO). 10-13 Oct. 2016.10.1109/RADIO.2016.7772027
Although RF exposure surveys have been carried out in the general environment using recently developed personal measurement devices (exposure meters), comprehensive measurement of exposure with a true population based sampling frame and a common protocol across countries has never been conducted. Within the FP-7 funded project Geronimo a personal RF exposure measurements in 5 European countries are conducted following a common measurement protocol. First measurements from 49 children and 49 parents in Slovenia yielded an average personal RF-EMF exposure of 0.26 V/m. Average personal RF-EMF exposure by technology was 0.11 V/m from uplink, 0.18 V/m from downlink, 0.15 V/m from broadcasting, 0.07 V/m from DECT and 0.08 V/m from WLAN.
Can body-worn devices be used for measuring personal exposure to mm waves?
Thielens A, Martens L, Joseph W. Can body-worn devices be used for measuring personal exposure to mm waves? Bioelectromagnetics. 2017 Jan 20. doi: 10.1002/bem.22036. [Epub ahead of print]
Fifth generation (5G) telecommunication networks will require more bandwidth and will use mm waves (30-300 GHz). Consequently, the aperture of antennas that are used for electromagnetic field measurements will be reduced in comparison to the ones currently used for lower frequencies (0.1-6 GHz). In combination with existing limits on incident power density prescribed by exposure guidelines, this provides an upper limit to received powers during exposure measurements. Simultaneously, an increase in the noise floor of transmitted signals will occur. These effects limit the dynamic range of measurements to 53 dB (2 × 105 ) at 300 GHz and 73 dB (2 × 107 ) at 30 GHz, which are determined using a simplified model. Additional propagation losses that exceed this dynamic range can occur during on-body measurements. Therefore, in future wireless networks, an on-body measurement of the incident power density cannot be guaranteed using a single antenna. This effect is problematic for both occupational measurements and epidemiological studies. We propose to use multiple, dynamic antennas on the body instead.
Measurements of intermediate-frequency electric and magnetic fields in households
Aerts S, Calderon C, Valič B, Maslanyj M, Addison D, Mee T, Goiceanu C, Verloock L, Van den Bossche M, Gajšek P Vermeulen 5, Röösli M, Cardis E, Martens L, Joseph W.Measurements of intermediate-frequency electric and magnetic fields in households. Environ Res. 2017 Jan 10;154:160-170. doi: 10.1016/j.envres.2017.01.001. [Epub ahead of print]
• Survey of residential electric and magnetic fields at intermediate frequencies (IF).
• IF-EF and -MF emitted by 280 household appliances were characterised.
• Strongest emitters were induction cookers, CFLs, LCD-TVs, and microwave ovens.
• No emissions exceeded ICNIRP limits (highest exposure quotient was 1.00).
Historically, assessment of human exposure to electric and magnetic fields has focused on the extremely-low-frequency (ELF) and radiofrequency (RF) ranges. However, research on the typically emitted fields in the intermediate-frequency (IF) range (300Hz to 1MHz) as well as potential effects of IF fields on the human body remains limited, although the range of household appliances with electrical components working in the IF range has grown significantly (e.g., induction cookers and compact fluorescent lighting). In this study, an extensive measurement survey was performed on the levels of electric and magnetic fields in the IF range typically present in residences as well as emitted by a wide range of household appliances under real-life circumstances. Using spot measurements, residential IF field levels were found to be generally low, while the use of certain appliances at close distance (20cm) may result in a relatively high exposure. Overall, appliance emissions contained either harmonic signals, with fundamental frequencies between 6kHz and 300kHz, which were sometimes accompanied by regions in the IF spectrum of rather noisy, elevated field strengths, or much more capricious spectra, dominated by 50Hz harmonics emanating far in the IF domain. The maximum peak field strengths recorded at 20cm were 41.5V/m and 2.7A/m, both from induction cookers. Finally, none of the appliance emissions in the IF range exceeded the exposure summation rules recommended by the International Commission on Non-Ionizing Radiation Protection guidelines and the International Electrotechnical Commission (IEC 62233) standard at 20cm and beyond (maximum exposure quotients EQE 1.0 and EQH 0.13).
Measurements of electric and magnetic fields at intermediate frequencies (IF) were performed in residences in three countries by way of a common protocol. Typical IF fields in the most frequented rooms were assessed as well as emissions from a wide range of household appliances. At distances of 1 m or more from the IF sources, field levels were found to be generally low. However, use of certain appliances at close distances (20–50cm), including induction cookers, LCD screens, microwave ovens and refrigerators with inverter technology, and (compact) fluorescent lighting, may result in exposures above 5% of public ICNIRP (2010) reference levels. In general, EF and MF emissions of household appliances in the IF range contained either harmonic signals, with fundamental frequencies between 6 and 293 kHz, which were sometimes accompanied by regions in the IF spectrum of rather noisy, elevated field strengths, or much more capricious spectra, seemingly dominated by 50 Hz harmonics emanating far in the IF domain. The maximum peak field strengths recorded in this study were 41.5 V/m and 2.7 A/m (both resulting from induction cookers) and at 20 cm and beyond none of the appliances exceeded the ICNIRP and IEC exposure summation rules (maximum observed electric- and magnetic-field exposure quotients were 1.00 and 0.13, respectively). The results reported here may provide a useful resource for epidemiological studies investigating the potential link between (adverse) health effects and exposure to IF fields.
Effect of Low Level Subchronic Microwave Radiation on Rat Brain
Deshmukh PS, Megha K, Nasare N, Banerjee BD, Ahmed RS, Abegaonkar MP, Tripathi AK, Mediratta PK. Effect of Low Level Subchronic Microwave Radiation on Rat Brain. Biomed Environ Sci. 2016 Dec;29(12):858-867. doi: 10.3967/bes2016.115.
OBJECTIVE: The present study was designed to investigate the effects of subchronic low level microwave radiation (MWR) on cognitive function, heat shock protein 70 (HSP70) level and DNA damage in brain of Fischer rats.
METHODS: Experiments were performed on male Fischer rats exposed to microwave radiation for 90 days at three different frequencies: 900, 1800, and 2450 MHz. Animals were divided into 4 groups: Group I: Sham exposed, Group II: animals exposed to microwave radiation at 900 MHz and specific absorption rate (SAR) 5.953 × 10-4 W/kg, Group III: animals exposed to 1800 MHz at SAR 5.835 × 10-4 W/kg and Group IV: animals exposed to 2450 MHz at SAR 6.672 × 10-4 W/kg. All the animals were tested for cognitive function using elevated plus maze and Morris water maze at the end of the exposure period and subsequently sacrificed to collect brain tissues. HSP70 levels were estimated by ELISA and DNA damage was assessed using alkaline comet assay.
RESULTS: Microwave exposure at 900-2450 MHz with SAR values as mentioned above lead to decline in cognitive function, increase in HSP70 level and DNA damage in brain.
CONCLUSION: The results of the present study suggest that low level microwave exposure at frequencies 900, 1800, and 2450 MHz may lead to hazardous effects on brain.
Open source paper: http://bit.ly/2jhXm84
Long-term exposure to 835 MHz RF-EMF induces hyperactivity, autophagy and demyelination in the cortical neurons of mice
Kim JH, Yu DH, Huh YH, Lee EH, Kim HG, Kim HR.Long-term exposure to 835 MHz RF-EMF induces hyperactivity, autophagy and demyelination in the cortical neurons of mice. Sci Rep. 2017 Jan 20;7:41129. doi: 10.1038/srep41129.
Radiofrequency electromagnetic field (RF-EMF) is used globally in conjunction with mobile communications. There are public concerns of the perceived deleterious biological consequences of RF-EMF exposure. This study assessed neuronal effects of RF-EMF on the cerebral cortex of the mouse brain as a proxy for cranial exposure during mobile phone use. C57BL/6 mice were exposed to 835 MHz RF-EMF at a specific absorption rate (SAR) of 4.0 W/kg for 5 hours/day during 12 weeks. The aim was to examine activation of autophagy pathway in the cerebral cortex, a brain region that is located relatively externally. Induction of autophagy genes and production of proteins including LC3B-II and Beclin1 were increased and accumulation of autolysosome was observed in neuronal cell bodies. However, proapoptotic factor Bax was down-regulted in the cerebral cortex. Importantly, we found that RF-EMF exposure led to myelin sheath damage and mice displayed hyperactivity-like behaviour. The data suggest that autophagy may act as a protective pathway for the neuronal cell bodies in the cerebral cortex during radiofrequency exposure. The observations that neuronal cell bodies remained structurally stable but demyelination was induced in cortical neurons following prolonged RF-EMF suggests a potential cause of neurological or neurobehavioural disorders.
Extremely low-level microwaves attenuate immune imbalance induced by inhalation exposure to low-level toluene in mice
Novoselova EG, Glushkova OV, Khrenov MO, Novoselova TV, Lunin SM, Fesenko EE. Extremely low-level microwaves attenuate immune imbalance induced by inhalation exposure to low-level toluene in mice. Int J Radiat Biol. 2017 Jan 9:1-9. doi: 10.1080/09553002.2017.1270473. [Epub ahead of print]
PURPOSE: To clarify whether extremely low-level microwaves (MW) alone or in combination with p38 inhibitor affect immune cell responses to inhalation exposure of mice to low-level toluene.
MATERIALS AND METHODS: The cytokine profile, heat shock proteins expression, and the activity of several signal cascades, namely, NF-κB, SAPK/JNK, IRF-3, p38 MAPK, and TLR4 were measured in spleen lymphocytes of mice treated to air-delivered toluene (0.6 mg/m3) or extremely low-level microwaves (8.15-18 GHz, 1μW/cm2, 1 Hz swinging frequency) or combined action of these two factors.
RESULTS: A single exposure to air-delivered low-level toluene induced activation of NF-κB, SAPK/JNK, IFR-3, p38 MAPK and TLR4 pathways. Furthermore, air toluene induced the expression of Hsp72 and enhanced IL-1, IL-6, and TNF-α in blood plasma, which is indicative of a pro-inflammatory response. Exposure to MW alone also resulted in the enhancement of the plasma cytokine values (e.g. IL-6, TNF-α, and IFN-γ) and activation of the NF-κB, MAPK p38, and especially the TLR4 pathways in splenic lymphocytes. Paradoxically, pre-exposure to MW partially recovered or normalized the lymphocyte parameters in the toluene-exposed mice, while the p38 inhibitor XI additionally increased protective activity of microwaves by down regulating MAPKs (JNK and p38), IKK, as well as expression of TLR4 and Hsp90-α.
CONCLUSIONS: The results suggest that exposure to low-intensity MW at specific conditions may recover immune parameters in mice undergoing inhalation exposure to low-level toluene via mechanisms involving cellular signaling.
Adverse and beneficial effects in Chinese hamster lung fibroblast cells following radiofrequency exposure
Sannino A, Zeni O, Romeo S, Massa R, Scarfi MR. Adverse and beneficial effects in Chinese hamster lung fibroblast cells following radiofrequency exposure.Bioelectromagnetics. 2017 Jan 10. doi: 10.1002/bem.22034. [Epub ahead of print]
In this study, the effect of radiofrequency (RF) exposure to 1950 MHz, Universal Mobile Telecommunication System signal, was investigated in Chinese hamster lung fibroblast cell line (V79). Genotoxic and cytotoxic effects of 20-h exposure at specific absorption rate (SAR) values from 0.15 W/kg to 1.25 W/kg were measured by means of cytokinesis-block micronucleus (MN) assay. Exposure was carried out blinded under strictly controlled conditions of dosimetry and temperature. The effect of RF exposure alone at four SAR values was tested, that is, 0.15, 0.3, 0.6, and 1.25 W/kg. A statistically significant increase in MN frequency was found in cultures exposed to 0.15 and 0.3 W/kg (P < 0.05) compared to sham-exposed ones, in the absence of cytotoxicity. SAR values of 0.6 and 1.25 W/kg did not exert any effect. Moreover, to evaluate the ability of RF to exert protective effects with respect to a chemical mutagen, cell cultures were also pre-exposed for 20 h at 0.3 or 1.25 W/kg, and then treated with 500 ng/ml of mitomycin-C (MMC). A significant reduction in the frequency of MN was detected in cultures pre-exposed to 1.25 W/kg compared to cultures treated with MMC alone (P < 0.05), indicating induction of adaptive response. Such a decrease was not induced by pre-exposure at 0.3 W/kg SAR. Taken together, our results indicated that V79 is a sensitive cell model to evidence either adverse or beneficial effects of RF exposure, depending on experimental conditions applied.
Study of potential health effects of electromagnetic fields of telephony and Wi-Fi, using chicken embryo development as animal model
Woelders H, de Wit A, Lourens A, Stockhofe N, Engel B, Hulsegge I, Schokker D, van Heijningen P, Vossen S, Bekers D, Zwamborn P. Study of potential health effects of electromagnetic fields of telephony and Wi-Fi, using chicken embryo development as animal model.Bioelectromagnetics. 2017 Jan 16. doi: 10.1002/bem.22026. [Epub ahead of print]
The objective of this study is to investigate possible biological effects of radiofrequency electromagnetic fields (RF-EMF) as used in modern wireless telecommunication in a well-controlled experimental environment using chicken embryo development as animal model. Chicken eggs were incubated under continuous experimental exposure to GSM (1.8 GHz), DECT (1.88 GHz), UMTS (2.1 GHz), and WLAN (5.6 GHz) radiation, with the appropriate modulation protocol, using a homogeneous field distribution at a field strength of approximately 3 V/m, representing the maximum field level in a normal living environment. Radiation-shielded exposure units/egg incubators were operating in parallel for exposed and control eggs in a climatized homogeneous environment, using 450 eggs per treatment in three successive rounds per treatment. Dosimetry of the exposure (field characteristics and specific absorption rate) were studied. Biological parameters studied included embryo death during incubation, hatching percentage, and various morphological and histological parameters of embryos and chicks and their organs, and gene expression profiles of embryos on day 7 and day 18 of incubation by microarray and qPCR. No conclusive evidence was found for induced embryonic mortality or malformations by exposure to the used EMFs, or for effects on the other measured parameters. Estimated differences between treatment groups were always small and the effect of treatment was not significant. In a statistical model that ignored possible interaction between rounds and exposure units, some of the many pairwise comparisons of exposed versus control had P-values lower than 0.05, but were not significant after correction for multiple testing.
Effects of extremely low-frequency electromagnetic field on expression levels of some antioxidant genes in human MCF-7 cells
Mahmoudinasab H, Sanie-Jahromi F, Saadat M. Effects of extremely low-frequency electromagnetic field on expression levels of some antioxidant genes in human MCF-7 cells. Mol Biol Res Commun. 2016 Jun;5(2):77-85.
In the past three decades, study on the biological effects of extremely low-frequency electromagnetic fields (ELF-EMFs) has been of interest to scientists. Although the exact mechanism of its effect is not fully understood, free radical processes has been proposed as a possible mechanism. This study was designed to evaluate the effect of 50-Hz EMFs on the mRNA levels of seven antioxidant genes (CAT, SOD1, SOD2, GSTO1, GSTM3, MSGT1, and MSGT3) in human MCF-7 cells. The EMF exposure patterns were: 1) 5 min field-on/5 min filed-off, 2) 15 min field-on/15 min field-off, 3) 30 min field-on continuously. In all three exposure conditions we tried to have total exposure time of 30 minutes. Control cultures were located in the exposure apparatus when the power was off. The experiments were done at two field intensities; 0.25 mT and 0.50 mT. The RNA extraction was done at two times; immediately post exposure and two hours post exposure. The mRNA levels were determined using quantitative real-time polymerase chain reaction. MTT assay for three exposure conditions in the two field intensities represented no cytotoxic effect on MCF-7 cells. Statistical comparison showed a significant difference between 0.25 mT and 0.50 mT intensities for "the 15 min field-on/15 min field-off condition" (Fisher's exact test, P=0.041), indicating that at 0.50 mT intensity field, the number of down-regulated and/or up-regulated genes increased compared with the other ones. However, there is no statistical significant difference between the field intensities for the two others EMF exposure conditions.
Investigation of terahertz radiation influence on rat glial cells
Borovkova M, Serebriakova M, Fedorov V, Sedykh E, Vaks V, Lichutin A, Salnikova A, Khodzitsky M. Investigation of terahertz radiation influence on rat glial cells. Biomed Opt Express. 2016 Dec 14;8(1):273-280. doi: 10.1364/BOE.8.000273. eCollection 2017.
We studied an influence of continuous terahertz (THz) radiation (0.12 - 0.18 THz, average power density of 3.2 mW/cm2) on a rat glial cell line. A dose-dependent cytotoxic effect of THz radiation is demonstrated. After 1 minute of THz radiation exposure a relative number of apoptotic cells increased in 1.5 times, after 3 minutes it doubled. This result confirms the concept of biological hazard of intense THz radiation. Diagnostic applications of THz radiation can be restricted by the radiation power density and exposure time.
... It is known that THz radiation causes a variety of biological effects, including some at the cellular level. Detailed reviews on this issue can be found in papers [2–7]. Influence of THz radiation on cells is revealed in the change of genes activity and cell membrane status. It was also reported before, that THz radiation changes the electrical charge of the membrane of human red blood cells [8, 9], causes a violation of the adhesive properties of the nerve cell membrane of a snail and mollusk [10, 11]. An indication of the structural damage is the increase in membrane permeability, as it was shown in some experiments with human red blood cells and lymphocytes , and laboratory rats red blood cells [13, 14].
Among the cellular effects, the cytotoxic effect of THz radiation is also an issue of concern for many scientists. Currently, there is no consensus on this issue. Some studies have demonstrated that this effect does not occur [18–25], whereas in other works the effect was clearly displayed [10–12, 26–28]. Particularly, experiments in papers [19, 20, 25, 28] showed different results after exposure of THz radiation of approximately same frequency (0.10 – 0.15 THz) and power density (0.04 – 5 mW/cm2). In all mentioned experiments, registration of the effect was carried out using adequate methods; however, the samples under exposure were different. It is possible that presence or lack of the effect is associated with the properties and characteristics of some particular cells. For this investigation, glial cells were selected as the samples of the experiment. They are highly sensitive to the ionic changes in environment . One of the mechanisms of THz radiation impact on living systems may be a disturbing effect on the status of the cell endogenous field, which will lead to changes in the ionic fluxes from a cell to environment and vice versa, and affect cell viability.
Conclusion In this investigation, we demonstrated a dose-dependent cytotoxic effect of THz radiation on rat glial cells. In the experiment, a C6 rat glial cell line was exposed by continuous THz radiation (0.12 – 0.18 THz) at average power density of 3.2 mW/cm2. After one minute of exposure, a relative number of apoptotic cells increased by a factor of 1.5, after 5 minutes it became 2.4 times higher than the initial value. This result confirms the concept of biological hazard of intense THz radiation. Therefore, we claim that diagnostic applications of THz radiation can be restricted by the radiation power density and exposure time.
Joel M. Moskowitz, Ph.D., Director
Center for Family and Community Health
School of Public Health
University of California, Berkeley
Electromagnetic Radiation Safety