Electromagnetic Fields from Mobile Phones do not Affect the Inner Auditory System of Sprague-Dawley Rats

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.

The effect of radiofrequency radiation generated by a Global System for Mobile Communications source on cochlear development in a rat model

OBJECTIVE

This study aimed to determine the effect of radiofrequency radiation generated by 900 and 1800 MHz Global System for Mobile Communications sources on cochlear development in the rat model.

METHODS

Eight pregnant albino Wistar rats were divided into three groups: control, 900 MHz and 1800 MHz. The latter two groups of pregnant rats were exposed to radiofrequency radiation for 1 hour per day starting on the 12th day of pregnancy until delivery. The rats in the control, 900 MHz and 1800 MHz groups gave birth to 24, 31 and 26 newborn rats respectively. Newborn rats in the 900 MHz and 1800 MHz groups were exposed to radiofrequency radiation for 1 hour per day for 21 days after delivery. Hearing evaluations of newborn rats were carried out using distortion product otoacoustic emissions testing. Eight newborn rats were randomly selected from each group for electron microscopic evaluation.

RESULTS

Distortion product otoacoustic emission tests revealed no significant difference among the groups, but electron microscopic evaluation revealed significant differences among the groups with regard to the number of normal, apoptotic and necrotic cells.

CONCLUSION

The findings indicated cellular structural damage in the cochlea caused by radiofrequency radiation exposure during cochlear development in the rat 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 chronic exposure to cellular telephone electromagnetic fields on hearing in rats

Objective:

To study the effects of the electromagnetic field emitted by cellular telephones upon the inner ear of rats, using distortion product otoacoustic emissions.

Methods:

Forty Wistar Albino rats were used. Twenty newborn and 20 adult rats were divided into two groups of 10, one to participate in the study and one as a control. The rats were exposed to the electromagnetic field for 6 hours per day, for 30 consecutive days. Before and after the 30 day exposure period, distortion product otoacoustic emissions were measured in each group and a signal-to-noise ratio calculated, which was later used in statistical analysis.

Results:

For both the newborn and adult rat groups, there was no significant difference in distortion product otoacoustic emissions recorded before and after exposure to the cellular telephone electromagnetic field (p > 0.05).

Conclusion:

Exposure to the electromagnetic field emitted by cellular telephones, for 6 hours a day for 30 consecutive days, had no effect on the hearing of newborn or adult rats, at the outer ear, middle ear or cochlear level.

Adverse effects of excessive mobile phone use

INTRODUCTION

Research findings indicate that the use of mobile phones may lead to a number of symptoms such as headache, impaired concentration and memory, and also fatigue.

MATERIALS AND METHODS

The present study was designed to investigate whether the symptoms of ill health reported by young people may be associated with the use of mobile phone (MP) and to analyze its influence on health and development of medical students. The questionnaire was designed specifically for this study and contained items regarding health condition and health complaints as well as the frequency of MP use. The response rate was 86.6% (286 of 330 forms, completed by 73.77% males and 26.22% females).

RESULTS

Most of the subjects (83.57%) had some knowledge about the adverse effects of MP use. 76.92% of the students carried one mobile, and 23.08% more than one. 55.94%, of the subjects reported the average daily MP use of less than 30 min, 27.97%, of 30-60 min, 11.53%, of 60-90 min and 4.54% of more than 90 min. 16.08% of the subjects complained of headache and 24.48% of fatigue. Impaired concentration was reported by 34.27% of respondents, memory disturbances by 40.56%, sleeplessness by 38.8%, hearing problems by 23.07%, and facial dermatitis by 16.78%. The sensation of warmth within the auricle and behind/around the ear was reported by 28.32%. Out of 286 subjects who participated in this study, 44.4% related their symptoms to mobile phone use.

CONCLUSIONS

The findings of the present study indicate that mobile phones play a large part in the daily life of medical students. Therefore, its impact on psychology and health should be discussed among the students to prevent the harmful effects of mobile phone use.

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.

Exposure setup to study potential adverse effects at GSM 1800 and UMTS frequencies on the auditory systems of rats

To investigate possible biological effects of exposure to electromagnetic (EM) fields at the frequencies of global system for mobile communication (GSM) 1800 system and universal mobile telecommunication system (UMTS) on the auditory system of rats, an exposure setup for in vivo experiments is presented. The study was carried out in the framework of two European research projects. The target of the investigation was the cochlea. A dosimetric study was performed, both numerically and through direct measurements, to assess the interaction of the radiated fields and the dose distribution in the biological target. For the local exposure of rats, a loop antenna operating at the frequency bands of interest was designed, realised and characterised through numerical and experimental dosimetric procedures. Moreover, an exposure apparatus was set up, consisting of three arrays of four loop antennas, placed on three levels, thus allowing simultaneous exposure of 12 rats to give statistical power to the experiments. To isolate the exposure arrays, the setup was assembled by a wooden rack with EM field absorbing panels, inserted among the levels and at the four sides of the rack. Isolation was verified by direct measurements. Two exposure arrays were simultaneously supplied, whereas the third one was used for sham exposure. Blind exposure was achieved through a black box, hiding physical connections to the microwave power supply. During exposure sessions, rats were restrained in special plastic jigs for repeatable positioning, thus assuring the fixed level of dose in the target.