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(Database last updated on Mar 27, 2024)
| ID Number | 37 | |
| Study Type | In Vivo | |
| Model | 2450 MHz (PW, CW), 837 MHz (CW) exposure to rats and analysis of DNA breaks in brain cells | |
| Details | Sprague-Dawley (male) rats were exposed to circularly polarized 2450 MHz CW or PW (2-usec pulses, 500 pulses per second) microwaves for 2 hr +/- a 4 hour recovery period at SARs of 0.6 and 1.2 W/kg (whole body average), with localized brain SARs ranging from 0.5 to 2.0 W/kg in a circular waveguide (Guy et al (1979) Radio Sci 14(6S):63-74). Either immediately, or following a 4 hour recovery period, rats were sacrificed, brains removed, and DNA analyzed via comet assay for single strand breaks. Both CW and PW microwaves at 1.2 W/kg significantly increased single-strand and double-strand DNA breaks. In a follow-up study, rats were injected with 1 mg/kg melatonin or 100 mg/kg N-tert-butyl-alpha phenylnitrone (PBN) before exposure to 2450 MHz CW and PW microwaves as in previous studies. The single doses of melatonin or PBN were reported to reduce the level of single and double strand DNA breaks to original baseline levels, suggesting a mechanism of oxidative free radical generation by microwave exposure as causing the DNA damage. In subsequent studies funded by the WTR and performed in parallel with another laboratory to look at the effects of mobile phone specific signals, Sprague Dawley (male) rats were exposed for 2 hours to 837 MHz CW at average whole body SAR of 1, 2, & 4 W/kg. Brain cell DNA was analyzed by Singh's version of the comet assay at 4 hours post-exposure. An effect was initially observed at the lowest of three exposure levels used in this study, however this finding could not be reproduced in a second experiment. In the second experiment, DNA damage in brain cells of the sham-exposed rats was higher than that of the cage controls making it difficult to draw any conclusion from the data. This study was not reported by the authors, but was referred to by Tice et al. in their description of their own parallel study using the same exposure system, the same animal model, and the same comet assay at the 'WTR Second State of the Science Colloquium in Long Beach'. AUTHORS' ABSTRACT: Lai et al. 1997 (IEEE #5568): Previous research in our laboratory has shown that various effects of radiofrequency electromagnetic radiation (RFR) exposure on the nervous system are mediated by endogenous opioids in the brain. We have also found that acute exposure to RFR induced DNA strand breaks in brain cells of the rat. The present experiment was carried out to investigate whether endogenous opioids are also involved in RFR-induced DNA strand breaks. Rats were treated with the opioid antagonist naltrexone (1 mg/kg, IP) immediately before and after exposure to 2450 MHz pulsed (2 us pulses, 500 pps) RFR at a power density of 2 mW/cm2 (average whole body specific absorption rate of 1.2 W/kg) for 2 hours. DNA double strand breaks were assayed in brain cells at 4 hours after exposure using a microgel electrophoresis assay. Results showed that the RFR exposure significantly increased DNA double strand breaks in brain cells of the rat, and the effect was partially blocked by treatment with naltrexone. Thus, these data indicate that endogenous opioids play a mediating role in RFR-induced DNA strand breaks in brain cells of the rat. |
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| Findings | Effects | |
| Status | Completed With Publication | |
| Principal Investigator | University of Washington, USA - hlai@u.washington.edu | |
| Funding Agency | WTR, USA, NIEHS, USA, CTIA, USA | |
| Country | UNITED STATES | |
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