Effects of 900 MHz electromagnetic fields exposure on cochlear cells' functionality in rats: Evaluation of distortion product otoacoustic emissions

Exposure to 1800 MHz LTE electromagnetic fields under proinflammatory conditions decreases the response strength and increases the acoustic threshold of auditory cortical neurons

Increased needs for mobile phone communications have raised successive generations (G) of wireless technologies, which could differentially affect biological systems. To test this, we exposed rats to single head-only exposure of a 4G long-term evolution (LTE)-1800 MHz electromagnetic field (EMF) for 2 h. We then assessed the impact on microglial space coverage and electrophysiological neuronal activity in the primary auditory cortex (ACx), under acute neuroinflammation induced by lipopolysaccharide. The mean specific absorption rate in the ACx was 0.5 W/kg. Multiunit recording revealed that LTE-EMF triggered reduction in the response strength to pure tones and to natural vocalizations, together with an increase in acoustic threshold in the low and medium frequencies. Iba1 immunohistochemistry showed no change in the area covered by microglia cell bodies and processes. In healthy rats, the same LTE-exposure induced no change in response strength and acoustic threshold. Our data indicate that acute neuroinflammation sensitizes neuronal responses to LTE-EMF, which leads to an altered processing of acoustic stimuli in the ACx.

Experimental study of potential adverse effects on the auditory system of rabbits exposed to short-term GSM-1800 radiation

PURPOSE

The effects of the electromagnetic (EM) radiation emitted by a mobile phone on the central auditory system of rabbits are investigated in this paper. Auditory brainstem response (ABR) measurements were performed before and after short-term exposure to EM radiation.

MATERIALS AND METHODS

Excitation was provided by a GSM-1800 emitter placed in contact with the (randomly selected) ear of the anesthetized rabbit/subject. The latency of waves I, II, III, IV, V and the interpeak latencies I-III, I-V, III-V were recorded, for both ears, before (baseline recordings) and after 1, 15, 30, 45 and 60 minutes of exposure to the EM radiation. The repeated measures one-way analysis of variance (ANOVA) followed by the post hoc Tukey test for pairwise comparisons was performed in order to decide about the significance of the results.

RESULTS

The statistical tests indicated that, as regards the ear ipsilateral to the radiating module, the mean latencies of waves I, II, III, IV, V, I-III, I-IV after 60 min exposure, the mean latencies of waves I, III, IV, V, I-III, I-IV after 45 min exposure and the mean latencies of waves I, III, IV, V, I-IV after 30 min exposure, were significantly prolonged compared to the corresponding baseline values. Statistically significant differences were also found for certain peak and interpeak latencies for 60 min exposure as compared with the corresponding results for 1 min and 15 min exposure. No statistically significant delay was observed for the latencies before and after the exposure, for the ear contralateral to the radiation source.

CONCLUSIONS

Although we found that more than 30 min exposure to GSM-1800 radiation resulted in prolongation of certain ABR components of rabbits, further investigation may be needed into the potential adverse effects on the auditory pathways.

The Effects of Mobile Phone Radiofrequency Radiation on Cochlear Stria Marginal Cells in Sprague-Dawley Rats

To investigate the possible mechanisms for biological effects of 1,800 MHz mobile radiofrequency radiation (RFR), the radiation-specific absorption rate was applied at 2 and 4 W/kg, and the exposure mode was 5 min on and 10 min off (conversation mode). Exposure time was 24 h short-term exposure. Following exposure, to detect cell DNA damage, cell apoptosis, and reactive oxygen species (ROS) generation, the Comet assay test, flow cytometry, DAPI (4',6-diamidino-2-phenylindole dihydrochloride) staining, and a fluorescent probe were used, respectively. Our experiments revealed that mobile phone RFR did not cause DNA damage in marginal cells, and the rate of cell apoptosis did not increase (P > 0.05). However, the production of ROS in the 4 W/kg exposure group was greater than that in the control group (P < 0.05). In conclusion, these results suggest that mobile phone energy was insufficient to cause cell DNA damage and cell apoptosis following short-term exposure, but the cumulative effect of mobile phone radiation still requires further confirmation. Activation of the ROS system plays a significant role in the biological effects of RFR. Bioelectromagnetics. © 2020 The Authors. Bioelectromagnetics published by Wiley Periodicals, Inc.

Audiometry results and TEOAE and DPOAE amplitudes in men taking a phosphodiesterase type 5 inhibitor for erectile dysfunction

We conducted a prospective study of transient evoked otoacoustic emissions (TEOAEs) and distortion-product otoacoustic emissions (DPOAEs) in men who were taking an oral phosphodiesterase type 5 (PDE5) inhibitor for erectile dysfunction. Our study group was made up of 30 men (60 ears), aged 34 to 60 years (mean: 50.9). They were randomly divided into three groups; 10 men were given sildenafil (Viagra) at 50 mg twice a week, 10 were given tadalafil (Cialis) at 20 mg twice a week, and 10 were given vardenafil (Levitra) at 20 mg twice a week. All patients took their drug for 3 weeks, for a total of 6 tablets for each patient. Audiometric tests and TEOAE and DPOAE measurements were performed before and after treatment. Post-treatment audiometry demonstrated improvement in hearing in all three groups. However, post-treatment TEOAE amplitudes and DPOAE amplitudes differed among the three groups; they were significantly higher in the sildenafil group at 1.0 kHz and the same in the tadalafil group; in the vardenafil group, the DPOAE amplitude was significantly lower at 3.0 kHz while there was no change in the TEOAE amplitude. We speculate that the possible mechanism for these findings is that PDE5 inhibitors block degradation of cyclic guanosine monophosphate (cGMP) and induce dilation of the cochlear microcirculation, resulting in an increase in cochlear blood flow. We also believe that the decrease in DPOAE amplitudes at 3.0 kHz seen in the vardenafil group may be related to an accumulation of nitric oxide/cGMP complex, which is toxic to the cochlea; however, since there was no change in TEOAE amplitude in the vardenafil group, this influence may be minimal. Further studies are needed to obtain a more comprehensive assessment of the effects of PDE5 inhibitors on hearing with the use of higher doses and longer durations of therapy.

Sensitivity of spiral ganglion neurons to damage caused by mobile phone electromagnetic radiation will increase in lipopolysaccharide-induced inflammation in vitro model

Background

With the increasing popularity of mobile phones, the potential hazards of radiofrequency electromagnetic radiation (RF-EMR) on the auditory system remain unclear. Apart from RF-EMR, humans are also exposed to various physical and chemical factors. We established a lipopolysaccharide (LPS)-induced inflammation in vitro model to investigate whether the possible sensitivity of spiral ganglion neurons to damage caused by mobile phone electromagnetic radiation (at specific absorption rates: 2, 4 W/kg) will increase.

Methods

Spiral ganglion neurons (SGN) were obtained from neonatal (1- to 3-day-old) Sprague Dawley® (SD) rats. After the SGN were treated with different concentrations (0, 20, 40, 50, 100, 200, and 400 μg/ml) of LPS, the Cell Counting Kit-8 (CCK-8) and alkaline comet assay were used to quantify cellular activity and DNA damage, respectively. The SGN were treated with the moderate LPS concentrations before RF-EMR exposure. After 24 h intermittent exposure at an absorption rate of 2 and 4 W/kg, DNA damage was examined by alkaline comet assay, ultrastructure changes were detected by transmission electron microscopy, and expression of the autophagy markers LC3-II and Beclin1 were examined by immunofluorescence and confocal laser scanning microscopy. Reactive oxygen species (ROS) production was quantified by the dichlorofluorescin-diacetate assay.

Results

LPS (100 μg/ml) induced DNA damage and suppressed cellular activity (P < 0.05). LPS (40 μg/ml) did not exhibit cellular activity changes or DNA damage (P > 0.05); therefore, 40 μg/ml was used to pretreat the concentration before exposure to RF-EMR. RF-EMR could not directly induce DNA damage. However, the 4 W/kg combined with LPS (40 μg/ml) group showed mitochondria vacuoles, karyopyknosis, presence of lysosomes and autophagosome, and increasing expression of LC3-II and Beclin1. The ROS values significantly increased in the 4 W/kg exposure, 4 W/kg combined with LPS (40 μg/ml) exposure, and H₂O₂ groups (P < 0.05, 0.01).

Conclusions

Short-term exposure to radiofrequency electromagnetic radiation could not directly induce DNA damage in normal spiral ganglion neurons, but it could cause the changes of cellular ultrastructure at special SAR 4.0 W/kg when cells are in fragile or micro-damaged condition. It seems that the sensitivity of SGN to damage caused by mobile phone electromagnetic radiation will increase in a lipopolysaccharide-induced inflammation in vitro model.

Biomedical signal and image processing

Generally, physiological modeling and biomedical signal processing constitute two important paradigms of biomedical engineering (BME): their fundamental concepts are taught starting from undergraduate studies and are more completely dealt with in the last years of graduate curricula, as well as in Ph.D. courses. Traditionally, these two cultural aspects were separated, with the first one more oriented to physiological issues and how to model them and the second one more dedicated to the development of processing tools or algorithms to enhance useful information from clinical data. A practical consequence was that those who did models did not do signal processing and vice versa. However, in recent years,the need for closer integration between signal processing and modeling of the relevant biological systems emerged very clearly [1], [2]. This is not only true for training purposes(i.e., to properly prepare the new professional members of BME) but also for the development of newly conceived research projects in which the integration between biomedical signal and image processing (BSIP) and modeling plays a crucial role. Just to give simple examples, topics such as brain–computer machine or interfaces,neuroengineering, nonlinear dynamical analysis of the cardiovascular (CV) system,integration of sensory-motor characteristics aimed at the building of advanced prostheses and rehabilitation tools, and wearable devices for vital sign monitoring and others do require an intelligent fusion of modeling and signal processing competences that are certainly peculiar of our discipline of BME.

Effect of electromagnetic field induced by radio frequency waves at 900 to 1800 MHz on bone mineral density of iliac bone wings

OBJECTIVE

Telecommunication has gained a different meaning in daily life with the introduction of the mobile phone system. However, electromagnetic pollution has increased in parallel to this improvement. In this study, we aimed to investigate the effects of electromagnetic waves emitted from cellular phones operating at a frequency of 900 to 1800 MHz on the bone mineral density of the human iliac bone wings, which are the most common carriage sites for mobile phones.

MATERIALS AND METHODS

A total of 150 male volunteer participants were included in this study. The mean age was 31.85 years, and the age range was between 21 and 57 years. The participants were separated into 2 groups based on as follows: iliac side exposed to electromagnetic wave (group 1) and unexposed side (group 2). Of the total number of participants, 122 were carrying their phones on their right iliac wings, whereas 28 were carrying their phones on their left iliac wings. The mean daily carriage duration was 14.7 hours (between 12 and 20 h), and the mean duration for cellular phone use was 6.2 years (between 4 and 9 yr). Mineral bone density was measured using dual-energy x-ray absorptiometry in the right and the left iliac wings of all the participants. The SPSS 15 software (SPSS Inc, Chicago, IL) was used for statistical analysis. In the comparison of the 2 sides, Student t test was performed and P < 0.05 was considered significant.

RESULTS

The mean dual-energy x-ray absorptiometry values measured from group 1 were slightly lower than those from group 2, but there was no statistically significant difference between the groups (P > 0.05). In addition, the mean values of group 1 were not as low as those measured in osteopeny or osteoporosis cases.

CONCLUSIONS

Current data may suggest that taking into consideration cellular phone use when iliac bone graft is necessary in clinical practice would constitute an important factor for more favorable outcomes.

Effects of extremely low frequency electromagnetic fields on transient evoked otoacoustic emissions in rabbits

OBJECTIVE

Humans are continuously exposed to an extremely low frequency (ELF) of electromagnetic fields (EMF), transmitted from the common sources like power stations, electric transmission lines, communication and radio-television signal transmission units. The present study aimed to assess the effects of 5.068 kV/m and 10.182 kV/m electric fields, which refer to the lower and upper intensity limits beyond which hazardous effects can be observed, on the auditory functions of rabbits via transient evoked otoacoustic emission (TEOAE) recordings.

METHODS

The study was performed on 20 healthy adult female New Zealand White rabbits randomly divided into two groups and applied either 5.068 kV/m (Group 1) or 10.182 kV/m (Group 2) of electric field for 3h/day for 14 days. TEOAE responses were recorded on day 0 before the exposure (0-BE) and on the 6th (6th-AE) and 14th (14th-AE) days after the exposure (AE). Emission amplitudes at 1.0-4.0 kHz were analyzed.

RESULTS

In Groups 1 and 2, the amplitudes separately recorded on the 6th-AE day were not different from the amplitudes recorded on day 0-BE. On the 6th-AE day, the only significant difference was detected in the right ear recordings of Group 1 at the frequency of 1.5 kHz (p=0.007). In Group 1, at 1.5 kHz, the median 6th day AE value (3.8 dB SPL) for the right ear was significantly lower than the median BE value. No significant difference in terms of amplitudes was detected in the comparison of 14th day AE with day 0-BE recordings. In the comparison of the groups for the recordings obtained at all the time points, no statistically significant differences were found.

CONCLUSION

It was concluded that the TEOAE decrease at 1.5 kHz of the right ears of Group 1 on the 6th day AE was transient; and on the 14th day AE, no significant decrease was determined in the TEOAEs of both groups. Our results showed that the ELF EMFs have no significant effects on the hearing sensation of rabbits, the cochlear functions of whose were evaluated using TEOAE recordings.

Effects of extremely low frequency electromagnetic fields on distortion product otoacoustic emissions in rabbits

OBJECTIVE

Humans are continuously exposed to extremely low frequency (ELF), electromagnetic fields (EMF), transmitted from the common sources like power stations, electric transmission lines, communication and radio-television signal transmission units. The present study aimed to assess the effects of 50 Hz ELF-EMF of 5.068 and 10.182 kV/m electric fields, which refer to the lower and upper intensity limits beyond which hazardous effects can be observed, on the auditory functions of rabbits via Distortion Product Otoacoustic Emission (DPOAE) recordings.

METHODS

The study was performed on 20 healthy adult female New Zealand White rabbits randomly divided into two groups and applied 50 Hz ELF-EMF with either 5.068 kV/m (Group 1) or 10.182 kV/m (Group 2) of electric field for 3h/day during 14 days. DPOAE responses recorded on the 0th day before exposure (B-EMF) and on the 6th (A-EMF-6th) and 14th (A-EMF-14th) days after exposure (AE). Mean stimulus intensity and emission amplitudes at 1.0-8.0 kHz were analyzed.

RESULTS

In Group 2 rabbits, on 6th and 14th days, the DPOAE amplitudes were observed as increased at 1.5-4.0 kHz (at 2.0 and 4.0 kHz significantly) than B-EMF values. At 6.0 kHz, A-EMF-14th amplitudes were significantly lower than A-EMF values.

CONCLUSION

These results suggest that ELF EMFs might affect hearing functions by frequency dependent manner. Higher ELF EMFs exposure caused increase of cochlear activity. Ototoxic effect of 10.182 kV/m ELF EMFs may begin at the basal turn of the cochlea by reducing DPOAEs at high frequencies.

Effects of mobile phone exposure on time frequency fine structure of transiently evoked otoacoustic emissions

Mobile phones have become very commonly used worldwide within a short period of time. To date there is only limited knowledge about interaction between electromagnetic fields (EMFs) emitted by mobile phones and the auditory function. Moreover, there is widespread concern that there may be potential for harm. The aim of this study was to assess potential subtle changes in cochlear function by measuring the temporal and spectral fine structure of transiently evoked otoacoustic emissions (TEOAE) in normal hearing subjects after exposure to EMFs emitted by Global System for Mobile Communication (GSM) mobile phones. TEOAEs were recorded in 27 healthy young adults before and after 10 min of real or sham exposure in a double-blind design. TEOAE data were analyzed both globally (broadband analysis) and using the Wavelet Transform (analysis of the time-frequency fine structure). The broadband analysis revealed no significant effect on TEOAEs related to exposure, confirming results of previous studies; in addition, no significant change was detected in the analysis of the elementary wavelet components, suggesting that the temporal and spectral fine structure of TEOAEs is not affected by 10 min exposure to low-intensity EMFs emitted by GSM mobile phones.

Possible Combined Effects of 900 MHZ Continuous-Wave Electromagnetic Fields and Gentamicin on the Auditory System of Rats

The aim of this study was to evaluate the cochlear functionality of Sprague-Dawley rats exposed to electromagnetic fields at 900 MHz and to gentamicin by distortion product otoacoustic emissions, which are a well-known indicator of the status of the cochlea's outer hair cells. A population of 32 rats was divided into four groups: group 1 was treated with daily intramuscular injections of 150 mg/kg body weight gentamicin for 15 days; group 2 was treated with daily intramuscular injections of 150 mg/kg body weight gentamicin for 15 days and exposed to electromagnetic fields; group 3 was exposed to electromagnetic fields; group 4 was sham-exposed. Rats were exposed 2 h/day, 5 days/week for 4 weeks at a local SAR of 4 W/kg in the ear (continuous wave at 900 MHz). Distortion product otoacoustic emissions tests were carried out before, during and after the combined exposure. The analysis of the data showed no subchronic exposure to electromagnetic fields on the inner auditory system of rats in either normal ears or ears exposed to a well-recognized pathological agent.

High-resolution numerical model of the middle and inner ear for a detailed analysis of radio frequency absorption

In order to enable a detailed analysis of radio frequency (RF) absorption in the human middle and inner ear organs, a numerical model of these organs was developed at a spatial resolution of 0.1 mm, based on a real human tissue sample. The dielectric properties of the liquids (perilymph and endolymph) inside the bony labyrinth were measured on samples of ten freshly deceased humans. After inserting this model into a commercially available numerical head model, FDTD-based computations for exposure scenarios with generic models of handheld devices operated close to the head in the frequency range 400-3700 MHz were carried out. For typical output power values of real handheld mobile communication devices the obtained results showed only very small amounts of absorbed RF power in the middle and inner ear organs. Highest absorption in the middle and inner ear was found for the 400 MHz irradiation. In this case, the RF power absorbed inside the labyrinth and the vestibulocochlear nerve was as low as 166 microW and 12 microW, respectively, when considering a device of 500 mW output power operated close to the ear. For typical mobile phone frequencies (900 MHz and 1850 MHz) and output power values (250 mW and 125 mW) the corresponding values of absorbed RF power were found to be more than one order of magnitude lower than the values given above. These results indicate that temperature-related biologically relevant effects on the middle and inner ear, induced by the RF emissions of typical handheld mobile communication devices, are unlikely.