共查询到20条相似文献,搜索用时 31 毫秒
1.
This study is aimed to clarify whether effect of low-level microwave radiation on human brain differs at different modulation
frequencies. Resting EEG recordings were done on different groups of healthy volunteers. The 450 MHz microwave radiation modulated
at 40 and 70 Hz (15 subjects) and 217 and 1,000 Hz (19 subjects) frequencies was applied. The results of our previous study
at 7, 14 and 21 Hz modulation were included into analysis. Ten cycles of the exposure (1 min off and 1 min on) at each fixed
modulation frequencies were applied. The field power density at the scalp was always 0.16 mW/cm2. Our results showed that microwave exposure increased the EEG energy at EEG frequencies lower or close to the modulation
frequency. No effect was detected at EEG frequencies higher than the modulation frequency. Statistically significant changes
were caused by exposure in the EEG alpha and beta frequency bands; no significant effect was detected in the theta band. Our
results suggest that telecommunication devices with complex spectrum of modulation frequencies like mobile phone can affect
all human EEG frequency bands. 相似文献
2.
Maie Bachmann Hiie Hinrikus Kaire Aadamsoo Ülle Võhma Jaanus Lass Jekaterina Rubljova Anna Suhhova Viiu Tuulik 《The Environmentalist》2007,27(4):505-510
This study was aimed to evaluate differences in the effect of microwave exposure on patients with depressive disorder and
healthy subjects. Our experiments were carried out on a group of depressive patients (women, 18 subjects) and comparison group
of healthy volunteers (women, 18 subjects) exposed during 30 min to 450 MHz microwave radiation modulated at 1,000 Hz frequency.
The field power density at the scalp was 0.9 mW/cm2. As a subjective criteria of microwave effect, the Brief Affect Scale (BAS) and Visual Analogue Scale (VAS) before and after
each exposure procedure were used. The analysis of EEG was performed and ratio of the EEG beta and theta power was selected
as a measure for evaluation of the microwave effect. The BAS and VAS revealed rather improvement in subjective mood score
after exposure for majority of depressive subjects (11) and no changes for others (7). The EEG analysis detected differences
between calculated parameters for exposed and sham recordings in depression as well as healthy group. Statistically significant
changes were introduced by microwave for five patients with depressive disorder and for one healthy subject. The rate of subjects
affected by microwave in depression group (28%) was five times higher compared to that rate in healthy group (5.6%). 相似文献
3.
Eleni Nanou Vassilis Tsiafakis E. Kapareliotis Charalabos Papageorgiou Andreas Rabavilas Christos Capsalis 《The Environmentalist》2005,25(2-4):173-179
Summary The effects of electromagnetic fields (EMF) emitted by cellular phones on human electroencephalogram (EEG) were studied during
an auditory memory task. The experimental method and the experimental setup are introduced as a credible measurement method
of EEG. 19 normal subjects (10 women and 9 men) performed the memory task both with and without exposure to a 900 MHz signal,
emitted by a dipole antenna placed near the subjects' head. The energy of the EEG signals was calculated at the time domain.
A Fourier transform of the EEG signals was done and the EEG energy was also calculated at the frequency domain. As the Parseval's
theorem anticipates the energies were identical. The EEG energy was found concentrated at the four basic bands (α (8–13 Hz),
β(14–30 Hz), δ (0–4 Hz) and θ(5–7 Hz)). The primary concern of the present study was the gender related influence of EMF on
the spectral energy of EEG. The results show evidence of a strong gender—radiation interaction effect on the EEG energy and
on the peak amplitudes within each of the four rhythms. Without radiation the spectral power of males is greater than of females,
while under exposure the situation is reversed. Under the influence of EMF the spectral power of the males EEG is decreased
while that of the females is increased. In conclusion both the baseline EEG and the changes effected to the EEG power spectrum
under the influence of EMF seem to be gender dependent. 相似文献
4.
Maie Bachmann Ruth Tomson Jaan Kalda Maksim Säkki Jaanus Lass Viiu Tuulik Hiie Hinrikus 《The Environmentalist》2007,27(4):511-517
This study was aimed to investigate the changes in the human electroencephalographic (EEG) signal caused by modulated low-level
microwaves. The 450 MHz microwave exposure modulated at 40 Hz and 70 Hz frequencies was applied to a group of 15 volunteers.
The field power density at the scalp was 0.16 mW/cm2. Ten cycles of the exposure (1 min on and 1 min off) at both modulation frequencies were applied. Analysis of the EEG signal
was performed using three different methods: nonlinear method of scaling analysis for length distribution of low variability
periods (LDLVP), relative changes in EEG energy (S-parameter) and beta ratio (H-parameter). The analysis revealed significant changes caused by microwave for the whole group (H-parameter method). The exposure caused increase of the EEG beta power (S-parameter method). Statistically significant changes in EEG were detected for four subjects (26.7%) at 40 Hz modulation frequency
(LDLVP method). 相似文献
5.
Summary This study focuses on an origin of interaction mechanism of microwave radiation with nervous system—quasi-thermal field effect.
The microwave field can cause fluctuations and vibration of the charged particles and membranes in tissues. The hypothesis
is, that this phenomenon is similar to the effect caused by Brown motion initiated by temperature and results in the same
effects without rise in temperature. The electric field of 1 V/cm can introduce disturbance of the thermal equilibrium inside
a cell of 10 μm radius, which is equivalent to disturbance produced by temperature rise of 1 K. The hypothesis, that microwave
heating should cause an effect independent of the microwave modulation frequency, while field effect depends on modulation
frequency, was examined experimentally. The 450 MHz microwave radiation, modulated at 7, 14 and 21 Hz frequencies, power density
at the skin 0.16 mW/cm2, was applied. The experimental protocol consisted of two series of five cycles of the repetitive microwave exposure at fixed
modulation frequencies. Relative changes in EEG theta, alpha and beta rhythms of the group of 13 healthy volunteers were analysed.
Analysis of the experimental data shows that: (1) statistically significant changes in EEG rhythms depend on modulation frequency
of the microwave field; (2) microwave stimulation causes an increase of the EEG energy level; (3) the effect is most intense
at beta1 rhythm and higher modulation frequencies. These findings confirm the quasi-thermal origin of the effect, different
from average heating. 相似文献
6.
The present study investigated the influence of electromagnetic fields (EMF), similar to that emitted by mobile phones, on
brain activity. Ten women and ten men, matched for age and educational level, performed a short memory task (Wechsler test),
with simultaneous Electroencephalogram (EEG) recordings at 15 scalp electrodes, both without (baseline) and with exposure
to an 1,800 MHz signal. The EEG energy was found concentrated at the four basic EEG bands [α (8–13 Hz), β (14–30 Hz), δ (0–4 Hz), and θ (5–7 Hz)]. The analysis revealed that in the presence of EMF, the energy of the β band was significantly greater for females than for males at the majority of the electrodes. Since beta oscillation is associated
with the shift of attention during the perception, these findings may indicate that the particular EMF (1,800 MHz signal)
exerts an influence on this brain activity, which appears to be gender-related. 相似文献
7.
The aim of the study was to assess the long-term effects of electromagnetic radiation (EMR) on cardiovascular system of medical
staff in physiotherapy. A number of 52 exposed subjects (4 male and 48 female; aged 47.3 ± 8.7 years), and a control group
of 52 subjects, matched by sex and age, with similar job characteristics without EMR exposure were studied. The EMR exposure
from devices emitting at 50 Hz, 150 kHz, 27.12 MHz, 2.45 GHz, and optical radiation was assessed. The relative values of EMR
for the whole frequency range in each physiotherapy were calculated and the obtained quota was much larger than 1. The workload
and psychosocial factors were evaluated, too. The cardiovascular risk factors arterial pressure, lipid profile, body mass
index, waist/hip ratio, smoking, alcohol consumption, nutrition, family history of cardiovascular disease were studied. The
incidence of hypertension was moderate with the studied physiotherapists (26.9% v.s. 23.8% control group). The total cholesterol
(TC) and low-density lipoprotein cholesterol (LDL-C) were significantly higher in the exposed group. The odds ratios indicate
higher possibility of becoming dyslipidemic for the exposed to EMR subjects [for TC OR (95% CI) = 1.570 (1.048–2.351) and
for LDL-C OR (95% CI) = 1.840 (1.158–2.924)]. In conclusion, our data show that the EMR exposure of the medical staff in physiotherapy
could be associated with the adverse effects on cardiovascular system. 相似文献
8.
Regulation of microcirculation and other physiological processes have strong non-linear character and involves complex of
different processes, every process with own hierarchy in time and different frequencies. Traditional Fourier analysis does
not provide sufficient power and resolution to elucidate characteristic of low vasomotor frequencies. Therefore, we apply
a Time–frequency (wavelet) analysis on the signal obtained by Laser Doppler flow meter (LDF) at 25 healthy volunteers, exposed
at the same time to low frequency electromagnetic fields, used for physiotherapy. Signal processing include Matlab based algorithms
for digital signal processing (DSP) and Matlab Spectral analysis toolbox of simultaneous registered variations in Blood Pressure
(BP), Laser Doppler Flow (LDF), and Intravital microscopy (IVM). It provides useful information about regulatory mechanisms
and vegetative nervous system regulation of peripheral blood flow. Continuous changes in blood pressure variations and perfusion
of extremities were measured prior and after 10, 20, and 30 min ELF-EMF (10, 16, 20, and 30 mT), exposure. After wavelet analysis
of the blood flow signals and vasomotion changes signals, several frequency bands were distinguished: 0.0095–0.02 Hz; (α),
0.02–0.06 Hz; (β), 0.06–0.15 Hz; (γ), 0.15–0.4 Hz; (δ), and 0.4–1 Hz; (θ) for LDF data and 0.0095–0.4 Hz; (α), 0.4–0.75 Hz;
(β), 0.75–0.9 Hz; (γ), 0.9–1.2 Hz; (δ), and 1.2–2 Hz; (θ) for IVM data. In this study, overlapping of some frequency bands
between IVM and LDF data were found. Overlapping of the frequency bands has two ways of interpretation, one related with similarity
of the structures and tissues and other related with output of ELF-EMF stimulation. We used also correlation and cross-correlation
analysis to compare non-invasive (BP measurements and LDF) data, with invasive intravital microscopy (IVM) data (obtained
on animals in vivo), during ELF-EMF stimulation. IVM data were used as a reference value, for certain information of possible
mechanisms of biological response at the tissue and blood vessel level after ELF-EMF exposure with frequency in the range
from 10 to 50 Hz and magnetic flux density of 20 mT. Comparative analysis of IVM and LDF, frequency bands show that they have
statistical significant changes after ELF-EMF stimulation. Five subintervals were confirmed (α-, β-, γ-, δ-, and θ). The findings
indicate that local ELF-EMF exposure at the constant temperature of the media increases skin blood flow at the upper extremities
which have a contribution to the α-frequency band at IVM. 相似文献
9.
Maie Bachmann Maksim Säkki Jaan Kalda Jaanus Lass Viiu Tuulik Hiie Hinrikus 《The Environmentalist》2005,25(2-4):165-171
Summary This study focuses on discrimination of changes, produced by low-level microwave exposure in intensity and time variability
of the human EEG at rest. The power spectral density (PSD) method and nonlinear scaling analysis of the length distribution
of low variability periods (LDLVP) were selected for analysis of the EEG signal. During the study, 19 healthy volunteers were
exposed to a microwave (450 MHz) of 217 Hz frequency on-off modulation. The field power density at the scalp was 0.16 mW/cm2. The experimental protocol consisted of ten cycles of repetitive microwave exposure. Signals from frontal, temporal, parietal
and occipital EEG channels on EEG theta, alpha and beta rhythms were analysed. Exposure to microwave causes average increase
of EEG activity. LDLVP analysis discriminated significant effect in time variability for 2 subjects (11%). PSD method detected
significant changes in intensity for 4 subjects (21%). The effect of low-level microwave exposure is stronger on EEG beta
rhythm in temporal and parietal regions of the human brain. 相似文献
10.
Henrietta Nittby Bengt Widegren Morten Krogh Gustav Grafström Henrik Berlin Gustav Rehn Jacob L. Eberhardt Lars Malmgren Bertil R. R. Persson Leif G. Salford 《The Environmentalist》2008,28(4):458-465
We have earlier shown that radio frequency electromagnetic fields can cause significant leakage of albumin through the blood–brain
barrier of exposed rats as compared to non-exposed rats, and also significant neuronal damage in rat brains several weeks
after a 2 h exposure to a mobile phone, at 915 MHz with a global system for mobile communications (GSM) frequency modulation,
at whole-body specific absorption rate values (SAR) of 200, 20, 2, and 0.2 mW/kg. We have now studied whether 6 h of exposure
to the radiation from a GSM mobile test phone at 1,800 MHz (at a whole-body SAR-value of 13 mW/kg, corresponding to a brain
SAR-value of 30 mW/kg) has an effect upon the gene expression pattern in rat brain cortex and hippocampus—areas where we have
observed albumin leakage from capillaries into neurons and neuronal damage. Microarray analysis of 31,099 rat genes, including
splicing variants, was performed in cortex and hippocampus of 8 Fischer 344 rats, 4 animals exposed to global system for mobile
communications electromagnetic fields for 6 h in an anechoic chamber, one rat at a time, and 4 controls kept as long in the
same anechoic chamber without exposure, also in this case one rat at a time. Gene ontology analysis (using the gene ontology
categories biological processes, molecular functions, and cell components) of the differentially expressed genes of the exposed
animals versus the control group revealed the following highly significant altered gene categories in both cortex and hippocampus:
extracellular region, signal transducer activity, intrinsic to membrane, and integral to membrane. The fact that most of these
categories are connected with membrane functions may have a relation to our earlier observation of albumin transport through
brain capillaries. 相似文献
11.
N. M. Salem 《The Environmentalist》2005,25(2-4):241-246
Summary The thermal effect due to electromagnetic absorption by human tissues is investigated at different frequencies ranging from
101–1016 Hz. Special emphasis is being considered in the microwave band used in wireless communications of the mobile industry. The
present work examines basically the thermal effect that arises as the duration of exposure to the electromagnetic radiation
and its dosage is increased. Using a computer simulation, a semi-classical model is adopted, were the photon-phonon interaction
is mediated by a homogenous sample of identical elements, which are naturally in harmonic modes of vibration. The phonon lifetime
is also included in this work. These thermal effects decrease with frequency in conformity with experimental results. This
model is then extrapolated to the individual cells of a human tissue and the possible rise in temperature is estimated. 相似文献
12.
Cindy Sage 《The Environmentalist》2012,32(2):144-156
The meltdown and release of radioactivity (ionizing radiation) from four damaged nuclear reactors at the Fukushima Nuclear
Facility in Japan in March 2011 continues to contaminate air and ocean water even 1 year later. Chronic exposure to low-dose
ionizing radiation will occur over large populations well into the future. This has caused grave concern among researchers
and the public over the very long period of time expected for decommissioning alone (current estimate from official sources
is 30–40 years based on TEPCO in Mid-and long-term roadmap towards the decommissioning of Fukushima Daiichi nuclear power
units 1–4, 2011) and the presumed adverse effects of chronic, low-dose ionizing radiation on children, adults and the environment. Ultimately,
radioactive materials from Fukushima will circulate for many years, making health impacts a predictable concern for many generations
(Yasunari et al. in PNAS 108(49):19530–19534, 2011). There is long-standing scientific evidence to suggest that low-dose ionizing radiation (LD-IR) and low-intensity non-ionizing
electromagnetic radiation (LI-NIER) in the form of extremely low-frequency electromagnetic fields and radiofrequency radiation
(RFR) share similar biological effects. Public health implications are significant for reconstruction efforts to rebuild in
post-Fukushima Japan. It is relevant to identify and reduce exposure pathways for chronic, low-dose ionizing radiation in
post-Fukushima Japan given current scientific knowledge. Intentional planning, rather than conventional planning, is needed
to reduce concomitant chronic low-intensity exposure to non-ionizing radiation. These are reasonably well-established risks
to health in the scientific literature, as evidenced by their classification by World Health Organization International Agency
for Research on Cancer as Possible Human Carcinogens. Reducing preventable, adverse health exposures in the newly rebuilt
environment to both LD-IR and LI-NIER is an achievable goal for Japan. Recovery and reconstruction efforts in Japan to restore
the communications and energy infrastructure, in particular, should pursue strategies for reduction and/or prevention of both
kinds of exposures. The design life of buildings replaced today is probably 35–50 years into the future. Cumulative health
risks may be somewhat mitigated if the double exposure (to both chronic low-dose IR from the Fukushima reactors and LI-NIER
[EMF and RFR] in new buildings and infrastructure) can be dealt with effectively in early planning and design in Japan’s reconstruction. 相似文献
13.
Occupational noise exposure and noise-induced hearing loss (NIHL) has been recognised as a problem among workers in Indian
industries. The major industries in India are based on the processing of agricultural products. There are appreciable numbers
of pulse processing units spread throughout the country. The purpose of this study was to determine the prevalence of hearing
loss among pulse processing workers. As a part of hearing protection intervention, audiometric tests were conducted at the
binaural low (250–1,500 Hz), the binaural mid (1,500–4,000 Hz) and the binaural high (3,000–8,000 Hz) frequency averages.
The prevalence of hearing loss was determined based on hearing threshold levels (HTLs) with a low fence of 25 dB. Over 50%
of pulse processing workers (dana bazaar and dal mill) showed hearing loss in the noise-sensitive higher (binaural mid and
high) frequencies. The rate of hearing loss was particularly high among workers in the dal mill. The analyses show a higher
risk of prevalence of hearing loss among the dal mill workers compared to the workers associated with the grain preprocessing
activities. The study shows alarming signals of NIHL, especially in the dal mill workers. The occupational exposure to noise
could be minimised by efficient control measures through engineering controls, administrative controls and the use of personal
protective devices. Applications of engineering and/or administrative controls are frequently not feasible in developing countries
for technical and financial reasons. A complete hearing conservation programme, including training, audiometry and the use
of hearing protection devices, is the most feasible method for the protection of industrial workers from prevailing noise
in workplace environments in the developing countries. 相似文献
14.
Summary Biological effects of extremely low-frequency electromagnetic fields (ELF-EMF) on microcirculation were investigated in vivo by monitoring arteriole diameters in conscious mice. Measurements of blood vessel diameter were monitored 33 min non-stop
before during and after exposure with ELF-EMF and every 389 ms blood vessel diameter were calculated.
Using a dorsal skinfold chamber (DSC), and following caudal vein injection of FITC-dextran 250 kDa, the microvasculature (initial
arteriole diameter of 45–80 μm), was examined by intravital microscopy and video images were recorded for a total time of
33 min. Arteriole diameter was continuously measured by on-line analysis using a High-speed Digital Machine Vision System
CV-2100, using an edge-gap detection algorithm. Since vessel diameters exhibit rhythmic variation expressed by vasomotion,
for estimation of microcirculatory activity we used both raw data for frequency analysis of vasomotion (measured frequencies
of vasomotion were in the range 0.008÷0.1 Hz) and evaluate mean blood vessel diameter for each 1 min period of time, and make
a comparison between Pre, Exposure/Sham exposure and Post exposure periods, with the aim to evaluate possible changes in mean
blood vessel diameter as a result of ELF-EMF action.
During EMF exposure and post-exposure periods, arteriole diameters increased significantly compared with the pre-exposure
period, and the changes were larger during post-exposure. In contrast to sham exposure, vasodilatation of the microvasculature
was significantly greater during exposure and post-exposure to 16 Hz EMF. These findings suggest that ELF-EMF may have potential
therapeutic use benefit for treating vascular disorders. 相似文献
15.
G. Duranti A. Rossi N. Rosato G. Fazio G. Sacerdoti P. Rossi R. Falsaperla V. Cannelli R. Supino 《The Environmentalist》2005,25(2-4):113-119
Summary The biological effects of electromagnetic radiation at ultra high frequency on human keratinocytes were investigated. HaCaT
cell system, a spontaneously immortalized human keratinocytes cell line, was chosen as model since skin is usually exposed
to electromagnetic radiation at considered frequency more than inner tissues. HaCaT cells were exposed to a pure sinusoidal
field at a frequency of 900 MHz (average SAR levels ranging from 0.04 to 0.08 W/kg) in plane wave condition inside a GTEM
chamber for time intervals of 18 hours at a controlled temperature of 37∘C. Growth curves were obtained for exposed and control cells, and a reduction in the number of exposed cells in comparison
to unexposed ones was found; however the number of dead cells was not significantly different in exposed and unexposed samples.
In order to investigate whether the reduction in cell proliferation of exposed cells was due to the activation of a differentiative
process, the expression of two hallmarks of differentiation was examined. Both keratin 1 and involucrin expression was increased
in exposed in comparison to unexposed cells. These results suggest that this protocol of exposure to 900 MHz electromagnetic
field can trigger a differentiation program in HaCaT cells. 相似文献
16.
Henrietta Nittby Arne Brun Susanne Str?mblad Mehri Kaviani Moghadam Wenjun Sun Lars Malmgren Jacob Eberhardt Bertil R. Persson Leif G. Salford 《The Environmentalist》2011,31(2):140-148
Since the late 1980s, our group has examined the effects of radiofrequency electromagnetic fields (RF-EMF), including pulse-modulated waves of the type emitted by mobile phones, upon the blood?Cbrain barrier. In more than 2,000 rats, we have repeatedly demonstrated a passage of the rats?? own albumin from the blood through the brain capillaries into the surrounding brain parenchyma at SAR values down to 0.1mW/kg. In most of these experiments, the animals were exposed in TEM-cells, ventilated by an external electrical fan at 50 Hz. In the present study, we examined whether the extremely low frequency (ELF) magnetic fields from the fan (50 Hz, 0.3?C1.5 ??T) might add to the RF effect. Sixty-four rats were divided into 4 groups: RF only, ELF only and RF + ELF exposure plus a sham group. The GSM-900 MHz RF exposure was at the very low, nonthermal, average whole-body SAR level 0.4 mW/kg. Demonstration of the normally occurring albumin extravasation in the basal hypothalamus is our inbuilt control proving that the staining is reliable. Two full series of staining of the whole material gave negative results for hypothalamus. Not until we changed to avidin, biotin, and antibodies from a third supplier, we received an acceptable staining. Twenty-five percent of the RF animals had a pathological albumin leakage, while the ELF and RF + ELF groups with three and two pathological findings, respectively, were not significantly different from the control group. We conclude that the use of external fans has had no major influence upon the result. 相似文献
17.
Varsik Martirosyan Levon Markosyan Hrachik Hovhanesyan Karlen Hovnanyan Sinerik Ayrapetyan 《The Environmentalist》2012,32(2):157-165
The aim of this work was to investigate the frequency-dependent effects of extremely low-frequency electromagnetic field (ELF-EMF)
and mechanical vibration at infrasound frequency (MV at IS frequency or MV) on growth and development of Escherichia coli K-12, by using classical microbiological (counting colony forming units), isotopic, spectrophotometric and electronmicroscopic
methods. The frequency-dependent effects of MV and ELF-EMF were shown that they could either stimulate or inhibit the growth
and the division of microbes depending on the periods following exposure. However, the mechanism through which the MV and
ELF-EMF effects affect the bacteria cell is not clear yet. It was suggested that the aqua medium could serve a target through
which the biological effect of MV and ELF-EMF on microbes could be realized. To check this hypothesis, the frequency-dependent
effects (2, 4, 6, 8, 10 Hz) of both MV and ELF-EMF on the bacterial growth, division and their motility in cases of exposure,
the preliminary treated microbes-free medium and microbes containing medium were studied. Both MV and ELF-EMF effect on microbes
have frequency and post-exposure period duration-dependent characters. The [
3
H]-thymidine involving experiments shown that EMF at 4 Hz exposure has pronounced stimulation effect on cell proliferation while 4 Hz
MV has inhibition effect. But at 8–10 Hz, the both EMF and MV have inhibitory effects on cell proliferation. It is suggested
that 4 and 8 Hz EMF have different biological effects on microbes. 相似文献
18.
Chiyoji Ohkubo Hideyuki Okano Akira Ushiyama Hiroshi Masuda 《The Environmentalist》2007,27(4):395-402
Authors review the importance of studying the effects of electromagnetic fields (EMF) on microcirculatory system, especially
in respect of possibility that vasculature may have direct and indirect role in interaction of static magnetic fields (SMF).
We outline the physiological importance of microcirculation and relatively new methods of evaluation technique in vivo and
explain in details the local and/or whole body exposure effects of SMF with␣range of 0.3–180 mT, power frequency EMF with
range of 0.1–30 mT and microwaves at 1.5 GHz with range 0.08–8 W/kg brain average specific absorption rate (SAR) on microcirculatory
systems in different tissues in experimental animals. 相似文献
19.
Occupational exposure to radiofrequency (RF) and static magnetic fields at magnetic resonance imaging (MRI) suites is of continuing
concern to personnel who routinely work in this environment. Questions regarding the levels of occupational RF and static
field exposure have increased with the increasing demand for anesthetics to be administered in this environment. The present
study was thus designed towards addressing the above-mentioned problem by gaining information regarding exposure levels of
clinical personnel at MRI units in South Africa. Three 1.5 MRI units in Bloemfontein, South Africa were utilized to evaluate
the exposure of clinical personnel to the electromagnetic fields present in the MRI environment over a period of time and
during different clinical MRI procedures. Three rounds of measurements of RF fields in the MRI environment were done. All
the three measurement rounds were focused on the low frequencies, 5 Hz–32 kHz, as well as on the high frequencies, 300 kHz–40 GHz.
First round measurements were done to establish the background of the RF fields in and around the magnet room during an MRI
examination. Second round RF field measurements were done at a specific location, 1 m away from the bore on the right-hand
side of the bed, in the MRI room. The third round measurements were of the same format as the second round, but the specific
location was against the magnet bore. Two pieces of Narda Safety Test Solution instruments, the EFA-300 and EMR-300, were
used to measure the electromagnetic and magnetic exposure fields generated from the MRI scanners. Results of the measurements
indicate that the electromagnetic fields measured during different clinical procedures do not exceed the International Commission
on Non-Ionizing Radiation Protection (2000) guidelines in these units. Results from round two and three showed that the RF
and gradient exposure 1 m and up against the bore entrance does not exceed these guidelines (rms average over 6 min). Ongoing
new developments in MRI scanning create the need for continuously monitoring exposure of patients and workers to the EMF fields
in the MRI environment. 相似文献
20.
E. Battisti A. Albanese L. Bianciardi A. I. Fiaschi M. Rigato A. Vittoria G. L. Messa N. Giordano 《The Environmentalist》2009,29(2):190-195
The utility and the safety of the extremely low frequencies (ELF) electromagnetic fields in the treatment of numerous diseases
have been demonstrated. Moreover, the effects of these fields seem to depend on their respective codes (frequency, intensity,
waveform). We want to value the effects and the safety of the therapeutic application of a musically modulated electromagnetic
field (TAMMEF) system, which field is piloted by a musical signal and its parameters (frequency, intensity, waveform) are
modified in time, randomly varying within the respective ranges, so that all possible codes can occur during a single application.
Sixty subjects, affected by shoulder periarthritis were enrolled in the study and randomly divided into three groups of 20
patients each: the first exposed to TAMMEF, the second exposed to ELF, the third exposed to a simulated field. All subjects
underwent a cycle of 15 daily sessions of 30 min each and a clinical examination upon enrolment, after 7 days of therapy,
at the end of the cycle and at a follow-up 30 days later. All the patients of TAMMEF group and ELF group completed the therapy
without the appearance of side effects: they presented a significant improvement of the subjective pain and the functional
limitation, which remained stable at the follow-up examination. In those exposed to a simulated field group, there was no
improvement of the pain symptoms or articular functionality. This study suggests that the TAMMEF system is efficacious and
safe in the control of pain symptoms and in the reduction of functional limitation in patients with shoulder periarthritis.
Moreover, the effects of the TAMMEF system cover those produced by the ELF field. 相似文献