Cognitive Impairment and Neurogenotoxic Effects in Rats Exposed to Low-Intensity Microwave Radiation
Deshmukh PS, Nasare N, Megha K, Banerjee BD, Ahmed RS, Singh D, Abegaonkar MP, Tripathi AK, Mediratta PK. Cognitive Impairment and Neurogenotoxic Effects in Rats Exposed to Low-Intensity Microwave Radiation. Int J Toxicol. 2015 Mar 5. pii: 1091581815574348. [Epub ahead of print]
Abstract
The health hazard of microwave radiation (MWR) has become a recent subject of interest as a result of the enormous increase in mobile phone usage.
The present study aimed to investigate the effects of chronic low-intensity microwave exposure on cognitive function, heat shock protein 70 (HSP70), and DNA damage in rat brain. Experiments were performed on male Fischer rats exposed to MWR for 180 days at 3 different frequencies, namely, 900, 1800 MHz, and 2450 MHz. Animals were divided into 4 groups: group I: sham exposed; group II: exposed to MWR at 900 MHz, specific absorption rate (SAR) 5.953 × 10-4 W/kg; group III: exposed to 1800 MHz, SAR 5.835×10-4 W/kg; and group IV: exposed to 2450 MHz, SAR 6.672 × 10-4 W/kg. All the rats were tested for cognitive function at the end of the exposure period and were subsequently sacrificed to collect brain. Level of HSP70 was estimated by enzyme-linked immunotarget assay and DNA damage was assessed using alkaline comet assay in all the groups.
The results showed declined cognitive function, elevated HSP70 level, and DNA damage in the brain of microwave-exposed animals. The results indicated that, chronic low-intensity microwave exposure in the frequency range of 900 to 2450 MHz may cause hazardous effects on the brain.
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Male Fischer-344 rats (60 days old and weighing 150-200 g) were obtained from the central animal house facility of the institute and placed in individual-raised, galvanized-wired cages ... A total of 24 rats were divided into 4 groups (6 rats in each group): group I (Sham exposed) animals were maintained under the same conditions as that of other groups except microwave generator was kept on switch off mode; group II animals were exposed to MWR at 900 MHz, SAR 5.953 × 10−4 W/kg; group III animals were exposed to 1800 MHz, SAR 5.835 × 10−4 W/kg; and group IV animals were exposed to 2450 MHz, SAR 6.672 × 10−4 W/kg. During the exposure rats were restrained in closed boxes with dimension as length:30 cm × breadth:15 cm × height:20 cm divided into 4 compartments with few holes of 1-cm diameter to facilitate easy movement and breathing, respectively, kept at a distance of 100 cm from the source. At a time 1 group (6 rats) was exposed to whole-body MWR in GTEM cell (Amitech Electronics Ltd, India) at power level of 0.00 dBm for 2 h/day during light period for 5 days/week at the same time for 180 days ...
Public concerns are increasing on possible adverse effects of MWR used in mobile telephony on health. The human body is like an electrochemical instrument of exquisite sensitivity whose orderly functioning and control are underpinned by oscillatory electrical processes of various kinds, each characterized by a specific frequency, some of which happen to be close to those used in Global system for Mobile Communication (GSM). The exact mechanism behind the biological action of MWR exposure is still unknown. The present study provides evidence that low-intensity microwave exposure results in cognitive impairment, elevation in HSP level and DNA damage in rat brain.
In the present study, DNA damage was also observed in brain after chronic low-intensity MWR exposure. Earlier in our study, we found that low-intensity MWR exposure for 30 days is capable of interacting with DNA by unknown mechanism and causes single-strand DNA breaks. 11 It is apparent from our study that at such low level of microwave exposure and the range of frequency from 900 to 2450 MHz could be the genotoxic by indirect mechanism. The biochemical compounds in living cells are composed of charges and dipoles that can interact with electric and magnetic fields by various mechanisms. The high frequency EMF (2.45 GHz and 50 Hz modulated) exerts their genotoxic effects in male Wistar rats as evidenced by a significant increase in DNA strand breaks after 2 hours exposure per day to EMF for 35 days with whole-body SAR of 0.11 W/kg. 22 Campisi et al 23 reported an increase in oxygen radicals accompanied by an increase in DNA strand breaks in primary rat glia cells after exposure to high frequency field (900 MHz). Xu et al 24 reported that DNA adduct rate caused by oxygen radicals in the mitochondria of primary cultured neurons (nerve cells) significantly increased after 24 hours GSM exposure. The increase in single- and double-strand DNA breaks was observed in brain cells of rats exposed to 2450 MHz for 2 hours at whole-body SAR 0.6 W/kg. 25,26 Usikalu M et al 27 reported that low SAR and 2.45 GHz MWR exposure can induce a single-strand break in brain cells of rats. Thus, we are confronted with the question whether or not the same deleterious alteration may also occur in brain from regular microwave exposure. Therefore, it would be necessary to further explore the differential effects of different exposure parameters such as frequency, duration of exposure, and pattern.
The present study demonstrates that exposure to low-intensity MWR leads to harmful effects on rat brain as evidenced by declined cognitive function, increased HSP70 and DNA damage. To better understand the molecular mechanism of action on cognitive function further studies with different intensities and durations of microwave exposure are needed.
--Joel M. Moskowitz, Ph.D., Director
Center for Family and Community Health
School of Public Health
University of California, Berkeley
Electromagnetic Radiation Safety
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