South Asian J Exp Biol; 5 (5): 167-173; 2015
ISSN: 2230-9799
Vol. 5, Issue 5, Page 167-173
http://www.sajeb.org
REGULAR ARTICLE
Thermal effect of chronic mobile phone radiation exposure at frequency 1800 MHz on adult Sprague-Dawley rats Ali S. H. Alchalabi*, Erkihun Aklilu, Abd Rahman Aziz, and Mohd Azam Khan Faculty of Veterinary Medicine, UMK City Campus, Pengkalan Chepa, Locked Bag 36, 16100 Kota Bharu, Kelantan, Malaysia ARTICLE INFO
ABSTRACT
Article History: Received: 16 Dec 2015 Revised: 30 Dec 2015 Accepted: 4 Jan 2016
The mobile communication technology, although integral to our everyday life, has been accounted to suffer negative impacts on the living body via two effects, thermal and non-thermal. The aims of this study were to assess the thermal effects by using Infra-red camera techniques and thermographic analysis and to find out how much electromagnetic fields from mobile phones contribute to increase the skin temperature due to thermal effects from chronic exposure to Global System for Mobile communication (GSM) mobile phone radiation. Eighty female Sprague Dawley rats were employed throughout the experiment, and the animals were dealt into four groups, control, 15, 30 and 60 days respectively (n=20) for 1h/day whole body exposure at SAR levels of 0.048 W/Kg. GSM-like signals at a frequency of 1800 MHz were provided by a signal generator. Thermographic analysis was done by using FLIR Tool software to estimate the changes in skin temperature in different regions of the physical structure. Statistical analysis shows significant changes in skin temperature between unexposed and exposed groups for 15 and 30 days of exposure (P< 0.001). While the skin temperature of 60 days exposure group remained consistent with unexposed group values. Our data suggest that mobile phone radiation at frequency 1800 MHz has a thermal effect represented by skin temperature rises in the whole body. The infra-red image analysis results are anticipated to help change mobile phone users' behavior to minimize the negative effects of mobile phone radiation.
*Corresponding Author: Email:
[email protected] Phone: +60112947731 Keywords: Thermal effect, mobile phone radiation, thermographic analysis, rats
1. Introduction There are plenty of research works that concentrate on cellular phone radiation interaction with the biological system via the non-thermal pathway. However, researches highlighting the thermal effect of mobile phone radiation interaction with biological systems is scant. Heavy usage of mobile phone resulting in heating or burning sensation in the ear and surrounding skin in most telephone users is due in part to the radiation energy ab-
sorbed by the tissues resulting in an increased skin temperature (Straume et al., 2005). Thermal effect is linked to specific absorption rate (SAR) which is distinguished as the rate of radiofrequency energy absorbed by a unit of mass of a body and measured by Watt/kg (Panagopoulos et al., 2013). SAR values are inversely affected by the distance between the body and the mobile phone and the nearest the distance the higher the value (C. Kargel, 2005). Heat is correlated with an SAR of electromagnetic radiation (EMR) resulting from boosting a tissue 167
Alchalabi et al., South Asian J Exp Biol; 5 (5): 167-173; 2015 electrical conductivity and which in turn may lead room as provided in Figure 1 our earlier publication to disruption of cell function and development (Fnu (Alchalabi et al., 2015) (Figure 1). et al., 2007). Wage increase in tissue temperature is associated with an imbalance between heat generation and dissipation (Ahmed & Kumar, 2013). Heat generation depends upon the pace of energy emitted from mobile devices, and that should be more than the rate of 100mW/cm2 to have a thermal effect upon the body tissues. Heat loss from the body takes place through various pathways, including high-temperature transfer to other tissues, transmission through blood vessels and radiation to the surrounding area (Habash, 2001). The Institute of Electrical and Electronics Engineering (IEEE), and International Commission on Non- Figure 1: Showing the EMF exposure setup using GSM like Ionizing Radiation Protection (ICNIRP) had given radiofrequency generator system. regulations associated with utilization of wireless communication devices with time to reduce the The EMF setup was applied as following setup; a risky effects of these technologies over time (IEEE, rectangular pulse with a repetition frequency 217 1999; ICNIRP, 2009). The fields on the thermic Hz for modulated signal amplitude at a duty cycle effect of electromagnetic waves (EMW) were of 1:8 similar to GSM dominant (pulse's width served on specific regions of the human torso 0.576 msec.) . During the exposure period, a 20 dB (head region) to measure the SAR and/or to evalu- (0.1 W) power was provided by the radiofrequency ate the skin temperature using commercial cellular radiation (RFR) generator (Budak et al., 2009; Tomphones at different frequencies (Kargel, 2005; ruk et al., 2010; Güler et al., 2012). Straume et al., 2005; Bhat, 2013). Another study in Animals were kept in Plexiglas cages, a specially 2011 was done by using Wireless Fidelity (Wi-Fi) designed exposure Plexiglas box (60 cm x 40 m x 20 frequency 2.46 GHz to analyze the thermographic cm) was used during the exposure time because image of exposed mice after four weeks Wi-Fi ex- Plexiglas is a non-conductive material that is not posures (Usman et al., 2011). The purpose of this affected by RF-EMR. The rats were allowed to study was to ascertain how much electromagnetic breed at room temperature 24 ±1 Cº and humidity fields from mobile phones contribute to the salary 60 ± 10% (relative humidity) with light / dark cycle increase in skin temperature as a result of thermal 12-12 hour in the laboratory animal research unit effects of continuing exposure to Global System for of the faculty of veterinary medicine, (UMK), tap Mobile communication (GSM) mobile phone radia- water and standard rat pellet were provided ad tion at 1800 MHz frequency. libitum. 2. Materials and Methods
2.2. Infra-red (IR) camera
2.1. Animal and experimental design
FLIR i5 IR camera with 100 × 100 resolution and < 0.1°C sensitivity and 10,000 pixels (FLIR system Inc, USA) was used for the infra-red images during the experiment. The thermal sensitivity is 0.1 °C at 30 ° C ambient temperature. The absolute temperature measured depends on the emissivity of the object, humidity and ambient temperature. FLIR Tools software was utilized for the analysis of thermographic images and the following values were chosen for all the images: emissivity 0.95, distance 1 m, reflected temperature 30 °C, atmospheric temperature 28 °C and humidity 60%. The effect on absolute temperature was carefully controlled by applying different values described above. For instance, when changing the setting of the temperature from 20 °C to 28
The study was conducted at the Faculty of Veterinary Medicine (FPV), Universiti Malaysia Kelantan (UMK). Eighty female Sprague Dawley rats were employed throughout the experiment, and the rats were distributed into four groups, control, 15, 30 and 60 days respectively (n=20) for 1h/day whole body exposure at SAR level 0.048 W/Kg. GSM-like signals at a frequency of 1800 MHz were provided by a signal generator (Agilent Technologies E8267D, 250 KHz – 20 GHz PSG Vector Signal Generator). An integrated pulse modulation unit and horn antenna (A-INFOMW Standard Gain Horn Antenna 1.7 – 2.6 GHz WR430, China) in an exposure
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Alchalabi et al., South Asian J Exp Biol; 5 (5): 167-173; 2015 °C, the recorded absolute temperature changed 0.1 °C or less which is equal to the sensitivity of the IR camera. Also changing humidity from 25 % to 60%, the emissivity of 1.0 – 0.98 and the distance from 1 m – 2 m the absolute temperature rose as expected by about 0.2 °C. 2.3. Body temperature measurements IR images of the unexposed animals (control group) and the exposed animals (exposure groups) were studied before and immediately at the remainder of each daily exposure until an end to the experiments (15, 30 and 60 days respectively). The IR images were analyzed and the temperatures of the whole body from the tip to the nose at the tail of the animal, i.e. head, flank and tail regions were taken, and each area was measured and both minimum and maximum temperatures in addition to the mean temperature were recorded. The calculation of the mean temperature for each region was performed for both lots of values, before and after exposure of each group. Change in temperatures between the groups (exposed and unexposed) was employed to examine the thermal effect of EMR. 2.4. Statistical data analysis
Analysis of variance was employed to examine the meaning between the difference in value for unexposed and exposed groups. The data were interpreted as mean ± Standard deviation (S.D.). Paired with one-tailed t-test was applied for testing the significance between values before and after exposure within the same groups and one-way ANOVA was employed to examine the significance between unexposed and exposed groups. Less significance difference (LSD) test was employed to assess the significance between groups and P values of less than 0.05 was considered as substantial. 3. Results We compared the temperature fluctuation within the control group before, and after the experiment and the dispute was not statistically significant (p< 0.625). While the analysis of variance of mean of skin surface temperature for whole body from the top of the nose to the remnant of the rear of the animal, head, flank and tail regions compared (p< 0.001). For 60 days of exposure, skin surface temperature was meaningfully lower than 15 and 30 days of exposure respectively. Maximum and minimum surface temperature information from different regions within the body also exhibited a significant increase in surface temperature values in ex-
posed animals compared to unexposed animals. (Table 1, 2). The FLIR i5 camera was utilized to get the reflected surface temperature of the rats throughout the experiment. The IR camera gives an accurate color measurement represent degrees of surface body temperature reflected from the rats and captured by IR sensor inside the camera. The colors run from white to dark blue. White color represents the highest temperature, and the dark blue represents lowest temperature and between clean and dark represent different temperatures depending on the strength of the gloss. Long term exposure to radiofrequency radiation (RFR) led to rise in the skin surface temperature from 1.3 upwards to 2.1 C° in certain body areas like the head and flank areas (Figure 2). Reflected body temperatures of unexposed animals exhibited normal heat distribution, which revealed asheat focused in the head and pelvis as the hottest parts in the body and the chest, flank and tail as cooler areas by colour gradient from the red (hot spot) to the blue (cold spot). In EMF exposed animals for the three different periods throughout the experiment, the IR images showed that the reflected body temperature of these animals was higher than unexposed animals represented by an increase of heated areas to cover most parts of the body starting from the head reaching the tail (Figure 3). Presence of sweating on some of the irradiated animals in parts of the fur-free, such as the soles of the feet after an end of exposure and the presence of wet bedding in the exposure cages for evidence of increased urination rate. Some cases of fatigue and slothful take time up to 1 - 2 hours after an end of exposure with continually twitch their tails from side to side were noticed, in addition to increasing the rate of drinking water. Exposed animals were cooling their bodies by pushing water bottles in order to moist their bodies. 4. Discussion The present study was conducted to investigate the thermal effect of chronic exposure to mobile phone radiation at frequency 1800 MHz on SpragueDawley rats. Thermographic image analysis helps to understand the thermal effect of such radiation, which is considered as part of microwave, range over three KHz – 300 GHz(McNamee J P & Chauhan, 2009; Nylund, 2011). A rise in tissue tempera169
Alchalabi et al., South Asian J Exp Biol; 5 (5): 167-173; 2015
Table 1: Effect of GSM-like signals at 1800 MHz frequency on surface body temperature Parameters Whole body Head Flank Groups Control 31.9269 ± 0.75 33.1050 ± 0.85 31.0975 ± 0.76 15-days exposure 34.1725 ± 0.28 c 34.8950 ± 0.57 c 33.5050 ± 0.67 c 30-days exposure 33.6425 ± 0.76 c 34.3275 ± 0.62 c 33.7575 ± 0.50 c 60-day exposure 31.9931 ± 0.49 * 33.2725 ± 0.75 * 32.1350 ± 0.53 * P value 0.001 0.001 0.001
Minimum 30.40 ± 0.94 32.71 ± 0.44 c 32.83 ± 0.85 c 30.31 ± 0.69 * 0.001
Head (C°) Maximum 34.52 ± 0.67 35.81 ± 0.56 c 35.08 ± 0.71* a 34.51 ± 0.87 * 0.05
Minimum 31.69 ± 1.42 33.87 ± 0.77 c 33.46 ± 0.90 c 32.03 ± 1.16 * 0.001
Flank (C°) Maximum 32.99 ± 0.75 35.23 ± 0.38 c 34.45 ± 0.70 c 33.07 ±0.52 * 0.001
Tail
31.5925 ± 1.24 34.2375 ± 0.66 c 33.1600 ± 1.29 c 30.5800 ± 0.87 c* 0.001
Minimum 29.20 ± 1.04 31.77 ± 1.29 c 32.90 ± 0.74 c 31.20 ± 0.62 * 0.001
Tail (C°) Maximum 32.42 ± 1.21 35.42 ± 0.82 c 33.74 ± 151 c 31.56 ± 1.21 a 0.001
Values are Mean ± S.D., * p< 0.05 statistically significant within exposure groups. Litters mean significantly between the control and exposed group's c p< 0.001.
Whole body (C°) Maximum 33.42 ± 0.83 35.49 ± 0.41 c 34.54 ± 0.53 c 33.65 ± 0.64 * 0.001
Table 2: Effect of GSM-like signals at 1800 MHz frequency at maximum and minimum surface body temperature Parameter Groups Control 15-day exposure 30-days exposure 60-day exposure P value
Minimum 30.76 ± 1.38 33.05 ± 0.72 c 32.12 ± 1.50 c 29.59 ± 0.73 c 0.001
Values are Mean ± S.D., * p< 0.05 statistically significant within exposure groups. Litters mean significant between the control and exposed groups at a p< 0.05, c p< 0.001.
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Figure 2: Infra-red images analyzed by FLIR tool software for rats involved in the experiment. (A) Rat from control group showing normal distribution of heat reflected from its torso. (B, C and D) Radiated rats to mobile phone radiation at Frequency 1800 MHz for 15, 30 and 60 days respectively, showing the thermal effect of the mobile phone radiation.
Figure 3: IR images of different groups involved in this study, (A) unexposed group images showed heat distribution in the whole body, and heat is mainly focused in the head and pelvis while the other parts of the body had less heat reflection. A whole-body irradiation at average length 1h/day showed in (B) images of animals belong to 15 days of EMF exposure, (C) images of animals exposed to EMF for 30 days and (D) images of animals irradiated for 60 days. Animals in these three groups exhibited a thermal effect represented by whole-body heat distribution. 171
Alchalabi et al., South Asian J Exp Biol; 5 (5): 167-173; 2015 ture occurs due to asymmetry in the heat regulatory system within the body (heat generation and heat dissipation), heat generation based on SAR and power density of an emitted device which should not be more than 100mW/cm2. The heat dissipation involves three mechanisms; heat transfers to the adjacent tissues, convection through the blood stream and radiation to the surroundings (Hamada et al., 2011). Interaction between electromagnetic radiation (EMR) and biological materials leading to heat generation in a biological system occurs due to absorption and transferring of the electromagnetic energy to the tissues, and the absorption process includes thermal, vibrational, rotational and electric modes (i.e. EMR causes translational and vibrational excitation of the atoms inside the cell leading to heat generation) (Habash, 2001). The quantity of generating passion in the biological tissue depends on the quantity of absorbed energy from radiation, which in turn depends upon the frequency and the duration of exposure. Frequency is the chief component in heat generation as it might warm up tissues or disturb the cellular function and development (Güler et al., 2012). In rats, the thermolytic responses to inescapable heat stress involve two responses. The first response is cutaneous vasodilatation from vascularized exposed surfaces such as the hind end and such response depend on the positive thermal gradient between the dirty dog and its surroundings. The second response is the grooming behavior (Stricker & Hainsworth, 1971). Our data showed that GSMlike radiation causes elevation in the whole body temperature after 15 and 30 days of exposure as a result of heat stress in the exposed animals compared with the control group. While, temperature recordings of rats exposed for 60 days remained constant. The IR images' analysis also proved that the maximum and minimum temperatures in different portions of the torso were also higher in exposed animals compared with their counterparts in unexposed animals. The thermographic color gamut explains how the difference between unexposed and exposed animals due to long-term EMR exposure (chronic exposure or heavy use) is very clean, and the heating spots are highly widespread along the rats’ body. The results of our findings are in contraindicated with a previous report by Pelletier and co-workers (Pelletier Amandine et al., 2014). They establish that the tail temperature in exposed animal was more depressed than that of unexposed animals. In Pelletier et al. (2014) study, the researchers used low-intensity radiofrequency
electromagnetic field continuous waves (900 MHz), and the length from the antenna were about 80 cm far away from exposed rats’ boxes. Still, the data from our survey was similar to findings reported by Usman team group. Who found that 2.46 GHz exposure for 7 h/day for four weeks led to an increment in body temperature recorded by IRTC camera and increase in the rate of urine secretion as well as non-active animals compared to control group (Usman et al., 2011). In previous studies in which the mobile telephone was used to examine changes in the temperature inside the body and skin, especially in the brain area, it was noticed that radio waves from mobile phone lead to a cost increase in skin temperature. These findings were significant compared against the values entered in non-exposed parts within the body ( Hudson, J. W., & Dawson, 1975; Christian Kargel, 2004; Straume et al., 2005; Bhat, 2013). , and these consequences are similar to our findings. Thermoregulatory responses or grooming behavior to increase heat loss by sweating, tail cutaneous vasodilatation, increased rate of drinking water and increase the rate of urine secretion were clearly noted in exposed animals as compared to unexposed animals. The body temperature data and proportion of heat loss by evaporation explain how creatures are capable of holding a stable body temperature at the higher temperatures by the drying up process with increased panting in resting animals after exposure (Hudson, J. W., & Dawson, 1975). Urination appears to be involved with tail sweating in a process of heat loss. The rise in tail temperature between 33.5 – 35.5 C° lead to tail cutaneous vasodilatation which explains the function of tail in thermoregulatory action and acclimatization to heat stress. After vasodilation, the tail can lose up to 20% of the total heat production of the rat. The skin temperature of the rear was applied as an index of vasodilation to determine whether the critical temperature shifted with acclimatization to 11 °C, 20 °C, and 30 °C and suggest that the tail is a non-evaporative heat loss area at the animal (Rand et al., 1965). Acclimatization was evident in rats in the exposure group for 60 days due to the long period of heat stress, and this acclimatization explains why there is no difference between unexposed animal and animals exposed for 60 days. Thermographic images showed the rising skin temperatures were stationed in each of the head and flank region, which made us pay attention to the seriousness of thermal effect on critical organs in these parts, particularly the brain and ovaries as well as other vital organs in the tor172
Alchalabi et al., South Asian J Exp Biol; 5 (5): 167-173; 2015 so. 5. Conclusion Our data suggest that mobile phone radiation at frequency 1800 MHz has a thermal effect upon the physical structure as represented by skin temperature rises in the whole body recorded by FLIR i5 IR camera. The FLIR i5 IR camera is suitable for finding the changes over the surface temperature of the living and non-existing objects. We recommend extensive studies about the relationship between the thermal effect of the cellular phones and other wireless devices at different frequencies and pathogenesis of brain tumors and fertility in human and animals. Acknowledgements
Habash RWY (2001) Electromagnetic Fields and Radiation: Human Bioeffects and Safety. CRC Press. Hamada Alaa J, Singh A, Agarwal A (2011) Cell Phones and their Impact on Male Fertility : Fact or Fiction. The Open Reproductive Science Journal 5: 125–137. Hudson JW, Dawson TJ (1975) Role of the sweating from the tail in the thermal balance of the rat-kangaroo Potorous tridactylus. Australian Journal of Zoology 23(4): 453–461. Institute of Electrical and Electronics Engineers (1999) IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz. IEEE Std C95,1. International Comission on Non-Ionizing Radiation Protection (2009) Exposure to high frequency electromagnetic fields, biological effects and health consequences (100 kHz-300 GHz). Icnirp 16/2009. Kargel C (2004) Local Temperature Rises Caused by the Use of Commercial Mobile Phones. InfraMation.
We sincerely appreciate all people who patronized us in this project, especially the postgraduate committee /Ph.D. Faculty of Veterinary Medicine, University Malaysia Kelantan for financial support and approval of the project (FPV-PGSC-2014).
Kargel C (2005) Infrared Thermal Imaging to Measure Local Temperature Rises Caused by Handheld Mobile Phones. IEEE Transactions on Instrumentation and Measurement 54(4): 1513–1519.
A declaration of interest
Nylund R (2011) Proteomics analysis of human endothelial cells after short-term exposure to mobile phone radiation. Säteilyturvakeskus. http://www.stuk.fi and http://lib.tkk.fi/Diss/2011/ isbn9789524786584
The authors reported no conflicts of interest. The authors alone are responsible for writing and content of this article.
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