Wednesday, December 19, 2018

Does exposure to 4G LTE cell phone radiation impair cell phone users' health?

4G or the fourth generation of cellular technology is called Long Term Evolution or LTE.  This technology employs new digital signal processing and modulation to increase the capacity and speed of wireless telecommunications networks. 

The standard for LTE was finalized in December, 2008, and the first mobile phone to employ this technology was released in September, 2010. By the end of 2017, 41 countries supported LTE coverage over at least 75% of their land area. In North America, the number of LTE mobile devices in use, 365 millionnow exceeds the size of the population.

LTE was launched without any pre-market safety testing. To date, I have found only three peer-reviewed studies that examined the acute effects of exposure to LTE radiation on brain functioning and no research on health effects. Thus, we do not know whether long-term exposure to LTE radiation is safe.

The fifth generation of cellular technology, or 5G, is currently being launched in selected areas in a handful of countries. Although once again no pre-market safety testing was conducted, related research suggests various types of harm to humans and other species from exposure to 5G radiation.

The abstracts for the three LTE studies appear below.


Modulation of brain functional connectivity by exposure to LTE (4G) cell phone radiation

Wei Y, Yang J, Chen Z, Wu T, Lv B. Modulation of resting‐state brain functional connectivity by exposure to acute fourth‐generation long‐term evolution electromagnetic field: An fMRI study. Bioelectromagnetics. Published online 18 December 2018. 

Abstract

By now, the neurophysiological effect of electromagnetic field (EMF) exposure and its underlying regulating mechanisms are not well manifested. In this study, we aimed to investigate whether acute long‐term evolution (LTE) EMF exposure could modulate brain functional connectivity using regional homogeneity (ReHo) method and seed‐based analysis on resting‐state functional magnetic resonance imaging (fMRI). We performed the LTE‐EMF  exposure experiment and acquired the resting‐state brain activities before and after EMF exposure. Then we applied ReHo index to characterize the localized functional connectivity and seed‐based method to evaluate the inter‐regional functional connectivity. Statistical comparisons were conducted to identify the possible evidence of brain functional connectivity modulation induced by the acute LTE‐EMF exposure. We found that the acute LTE‐EMF exposure modulated localized intra‐regional connectivity (p < 0.05, AlphaSim corrected, voxel size ≥ 18) and inter‐regional connectivity in some brain regions (p < 0.05, AlphaSim corrected, voxel size ≥ 18). Our results may indicate that the approaches relying on network‐level inferences could provide deeper insight into the acute effect on human functional activity induced by LTE‐EMF exposure.

Excerpts

"Currently, multiple standards exist for wireless communication, which ranges from second‐generation (2G, GSM) to third‐generation (3G, UMTS) and fourth‐generation (4G, LTE) networks in daily life. Fifth‐generation (5G) networks will start to appear as a commercial infrastructure in the near future. Although we enjoy the convenience of mobile phones, the widespread use of them has raised attention about the possible health effects of radiofrequency (RF) electromagnetic field (EMF) exposure [ICNIRP, 1998].

With neuroimaging and neuropsychology tools, the effect of EMF on the human brain can be reflected as signals of electrical activity [Hamblin et al., 2006; Croft et al., 2010; Lustenberger et al., 2013; Roggeveen et al., 2015a, b], cortical excitability [Tombini et al., 2013], cerebral blood flow [Aalto et al., 2006], brain glucose metabolism [Volkow et al., 2011], and hemodynamic responses [Volkow et al., 2011; Curcio et al., 2012]. Previous studies reported that GSM signals modulated alpha band power in resting‐state electroencephalogram (EEG) [Croft et al., 2010] or some event‐related potential (ERP) components during cognitive tasks [Hamblin et al., 2006], whereas other studies did not detect any GSM exposure‐induced changes in brain activity [Curcio et al., 2012]. Although some studies showed no significant effects of 3G signals on any neurophysiological measurements [Zhang et al., 2017], recent EEG studies reported significant EEG alterations associated with 3G mobile phone radiation [Roggeveen et al., 2015a, b]. The inconsistency could partly be attributed to different exposure frequencies, modulation modes, and exposure durations [Zhang et al., 2017]. For 4G‐related signals, only our two previous studies have investigated the acute effect of long‐term evolution (LTE) EMF exposure on human brain function [Lv et al., 2014; Yang et al., 2016] using EEG and functional magnetic resonance imaging (fMRI). We found that 30 min of LTE‐EMF exposure modulated the alpha/beta EEG bands [Yang et al., 2016] and spontaneous low‐frequency fluctuations [Lv et al., 2014] in some brain regions. Since LTE networks have been widely deployed, we should make more effort to evaluate the possible effects of LTE‐EMF exposure from different perspectives."

"In this study, we aimed to investigate whether acute LTE‐EMF exposure could modulate brain functional connectivity using resting‐state fMRI. We performed LTE‐EMF exposure experiments lasting for 30 min under a controllable environment and recorded the resting‐state brain activities before and after EMF exposure. Then, we applied the regional homogeneity (ReHo) index [Zang et al., 2004] to characterize localized intraregional connectivity and the seed‐based functional connectivity method [Margulies et al., 2010] to evaluate interregional brain connectivity. Statistical comparisons were conducted to identify possible evidence of brain functional connectivity modulation induced by acute LTE‐EMF exposure."

“To eliminate study biases, we employed a double‐blind, crossover, randomized, and counterbalanced design. Each participant underwent two experimental sessions including real exposure and sham exposure, which were separated by 1 day….The time‐division LTE signal (2.573 GHz) was produced by a signal generator a standard formulation for LTE signals….The power delivered to the standard dipole of 2.6 GHz was 24 dBm (mean value), which was equivalent to a theoretical maximal emission by an LTE terminal. The experiments were conducted in a shielding room to avoid the influence of environmental EMF. Each exposure session lasted for 30 min.”

“Numerical simulations that yielded spatial peak SAR averaging over 10 g tissues for the subjects was 0.98 ± 0.27 W/kg, with a maximal value of 1.52 W/kg, which was below the safety limits [ICNIRP, 1998].”

“In our previous studies, we found that LTE‐EMF exposure depressed the amplitude of spontaneous low frequency fluctuations (ALFFs) in some brain regions [Lv et al., 2014], such as those surrounding the left superior temporal gyrus and middle temporal gyrus (STG_L and MTG_L), right superior temporal gyrus (STG_R), right medial frontal gyrus, and right paracentral lobule (MFG_R and PCL_R). In the present study, we found new evidence that acute LTE‐EMF exposures lasting for 30 min modulated brain functional connectivity including not only localized intraregional connectivity, but also interregional connectivity.”

"Although the SAR values by LTE‐EMF exposure indicated no obvious temperature increase during the exposure experiments and the brain was excellent in terms of thermal regulation, we could not preclude that thermal changes, even minute changes, could be responsible for the instantaneous changes in neural firing. SAR is a metric averaging over 6 min, and its applicability for neurological studies should be discussed."

Conclusion

"Our results may indicate that approaches relying on network‐level inferences can provide deeper insights into the acute effects of LTE‐EMF exposure with intensities below the current safety limits on human functional connectivity. In the future, we need to investigate the evolution of the effect over time.”



May 2, 2016

By the end of 2013, 100 million cell phones in the U.S. operated on LTE. This number worldwide is expected to exceed 1 billion by the end of this year. 


Following is a summary of the second study published on the effects of 4th generation LTE cell phone radiation on the brain activity of cell phone users by the China Academy of Telecommunication Research of the Ministry of Industry and Information Technology.

The original study showed that 30 minutes of exposure to LTE phone radiation affected brain activity in the left superior temporal gyrus, left middle temporal gyrus, right superior temporal gyrus, right medial frontal gyrus and right paracentral lobule. The current study found that a 30-minute exposure to LTE radiation modulated the EEG in the alpha and beta bands at the frontal region of the near and remote sides, and at the temporal region on the near side.


Long-Term Evolution EMF Exposure Modulates Resting State EEG on Alpha and Beta Bands

Yang L, Chen Q, Lv B, Wu T. Long-Term Evolution Electromagnetic Fields Exposure Modulates the Resting State EEG on Alpha and Beta Bands. Clin EEG Neurosci. 
2017 May;48(3):168-175. doi: 10.1177/1550059416644887.

Abstract


Long-term evolution (LTE) wireless telecommunication systems are widely used globally, which has raised a concern that exposure to electromagnetic fields (EMF) emitted from LTE devices can change human neural function. To date, few studies have been conducted on the effect of exposure to LTE EMF. Here, we evaluated the changes in electroencephalogram (EEG) due to LTE EMF exposure. An LTE EMF exposure system with a stable power emission, which was equivalent to the maximum emission from an LTE mobile phone, was used to radiate the subjects. Numerical simulations were conducted to ensure that the specific absorption rate in the subject's head was below the safety limits. Exposure to LTE EMF reduced the spectral power and the interhemispheric coherence in the alpha and beta bands of the frontal and temporal brain regions. No significant change was observed in the spectral power and the inter-hemispheric coherence in different timeslots during and after the exposure. These findings also corroborated those of our previous study using functional magnetic resonant imaging.

http://1.usa.gov/2475GM3

Excerpts

".. the results of resting state EEG experiments have been contradictory. For example, some studies have reported enhancement of the alpha (8-12 Hz) and beta (13-30 Hz) band power values after exposure to pulse-modulated 450- and 900-MHz signals, pulse-modulated magnetic fields, and active mobile phone signals. In contrast, some studies have shown decreased alpha band activity after 20 minutes of extremely low-frequency EMF exposure, or 5 minutes of magnetic field exposure, or global system for mobile communications (GSM) EMF exposure. Many studies also found no changes in the EEG after either modulated or unmodulated EMF exposure. These inconsistencies could be attributed not only to the differences in the signal type, the modulation, the exposure frequency, the exposure intensity individual anatomy, the ages of the subjects, and the exposure duration but also to the lack of rigorous experimental designs. Most of the previously published studies have focused on GSM, WiFi, and Universal Mobile Telecommunications System (UMTS), signals. An emerging technology, “long term evolution” (LTE) wireless service, has been deployed since 2009 and the number of global LTE subscribers is expected to reach 1.37 billion by the end of 2015. Other than our previous functional magnetic resonance imaging (fMRI) study, there are very few reports on the effect of exposure to LTE EMF on brain function. We previously found that 30 minutes of exposure to LTE EMF modulated the spontaneous low-frequency fluctuations. We were interested in confirming our previous results using another neurophysiological method and also sought to assess the evolution of the effect over time during such exposure. In this article, we have investigated for the first time the changes in the resting state EEG caused by exposure to LTE signals. The exposure dose was below the current safety limit. In order to assess brain activities on different levels, we evaluated spectral power and interhemispheric coherence, which allowed investigation of EEG changes in specific brain regions, as well as their correlations, at different time points. We show that exposure to LTE EMF decreased the alpha and beta band power spectrum and interhemisphere coherence."

"The age of the subjects was 30.2 ± 2.7 years."

"A plastic spacer of 1 cm was used to maintain the distance between the right ear and a standard dipole. We applied 2 power meters to ensure a constant incident power to the emission dipole. The power delivered to the dipole was 24 dBm (peak value), equivalent to a theoretical maximum emission by an LTE terminal."

"All 25 subjects participated in the double-blind and counterbalanced experiment."

"The experiment included 2 sessions, which were separated by 1 week. Each session lasted 50 minutes and comprised 5 time slots. We indicated each time slot (10 minutes) in a session as sub1 to sub5. The radiation dipole was power off for the first (preexposure, sub1) and the last 10 minutes (postexposure, sub5) timeslots. Subjects were exposed to real EMF exposure in the 3 time slots (sub2 to sub4) between the first and the last 10 minutes in only 1 of the 2 sessions. The order of the 2 sessions was randomly selected per subject. The subjects were not informed of the sequence of each session; however, they were aware of the possibility of being exposed. On the other hand, the staff who analyzed the data did not know the sources of the EEG traces."

"The simulations yielded 1.34 W/kg (pSAR10g) and 1.96 W/kg (pSAR1g), with the electrodes, and 1.27 W/kg (pSAR10g) and 1.78 W/kg (pSAR1g), without the electrodes (Figure 2) when the dipole emitted radiation. Therefore, the presence of the EEG electrodes increased pSAR10g and pSAR1g by about 5.5% and 10.1%, respectively. Accordingly, the maximum resultant temperature increase was no more than 0.1°C ...."

"Previous studies on GSM and UMTS signal exposure frequently reported changes in interhemispheric coherence and the spectral power in the alpha band in the frontal and temporal regions, which were also confirmed by our results on LTE EMF exposure. Moreover, modulation of the power spectrum in the beta band, including both an increase and a decrease, was reported. Several reasons may account for the inconsistency. First, the signal frequency and its modulation influenced the affected EEG band: for example, exposure to 2G signals affect the alpha rhythms, whilst exposure to 3G signals do not. In contrast, the modulated 450-MHz signals of various intensities can change beta activity much more markedly than alpha band power. Second, gender and the individual sensitivity 38,40 may influence the effect on different bands. Hence, we attempted to reduce the variability by enrolling the subjects with the same gender and age."

"In particular, power spectral analysis has shown significant differences in the left frontal brain regions, that is, the remote side, on exposure. This may be associated with modulation of neural activity in the remote/contralateral brain regions. The remote effects of EMF have been observed in many previous studies. Our results reconfirmed that the effects were also seen with LTE EMF exposure."

"The power spectrum and the interhemispheric coherence did not differ significantly over sub2 to sub5. Thus, the observed effect did not change with the exposure time and the effect was therefore not developing. The reduction in alpha band activity has been associated with a decrease in individual information-processing ability, alertness, and cognitive performance. The decrease in beta band activity could be interpreted as decreased alertness, arousal, and excitement or a low level of fatigue. Notably, EEG power fluctuation was not in one-one correspondence with the change in behavioral/cognitive performance which should be evaluated by specifically designed experiments as the report by Haarala et al. No conclusion could be obtained by our study that the present EMF exposure affected the subjects’ cognitive abilities."

"This work studied EEG changes caused by LTE EMF exposure. An exposure system with a fixed power incident to a radiation dipole was used; this simulation demonstrated that the SAR was within the safety limits. LTE EMF exposure modulated the EEG in the alpha and beta bands at the frontal region of the near and remote sides, and at the temporal region on the near side. No developing effect was found in the periods during and after the exposure. Our results agreed to some extent with those of our previous fMRI study on LTE exposure. Our finding indicated that the LTE EMF exposure with the intensity beneath the safety limits could modulate the brain activities."

"Future studies should focus on the correlation of EEG changes with spatial SAR distribution. By taking individual anatomical structure into consideration, a precise dose-effect relationship can be established. EEG changes with a finer temporal resolution during the exposure session should also be evaluated."

First LTE study

Lv B, Chen Z, Wu T, et al. The alteration of spontaneous low frequency oscillations caused by acute electromagnetic fields exposure. Clin Neurophysiol. 2014;125:277-286.

Abstract

OBJECTIVE: The motivation of this study is to evaluate the possible alteration of regional resting state brain activity induced by the acute radiofrequency electromagnetic field (RF-EMF) exposure (30 minutes) of Long Term Evolution (LTE) signal.

METHODS: We designed a controllable near-field LTE RF-EMF exposure environment. Eighteen subjects participated in a double-blind, crossover, randomized and counterbalanced experiment including two sessions (real and sham exposure). The radiation source was close to the right ear. Then the resting state fMRI signals of human brain were collected before and after the exposure in both sessions. We measured the amplitude of low frequency fluctuation (ALFF) and fractional ALFF (fALFF) to characterize the spontaneous brain activity.

RESULTS: We found the decreased ALFF value around in left superior temporal gyrus, left middle temporal gyrus, right superior temporal gyrus, right medial frontal gyrus and right paracentral lobule after the real exposure. And the decreased fALFF value was also detected in right medial frontal gyrus and right paracentral lobule.

CONCLUSIONS: The study provided the evidences that 30 minute LTE RF-EMF exposure modulated the spontaneous low frequency fluctuations in some brain regions.

SIGNIFICANCE: With resting state fMRI, we found the alteration of spontaneous low frequency fluctuations induced by the acute LTE RF-EMF exposure.

http://1.usa.gov/1gTqxVr