ID Number		1016
Study Type		In Vivo
Model		900 MHz (GSM) exposure to rats and analysis of neuron degeneration and cognitive impairment
Details		Fischer rats (n=32, male & female) exposed to 900 MHz (GSM) RF using a mobile phone as a signal generator fed into a TEM cell for 2 hours at 0.002, 0.02, and 0.2 W/kg (whole body average). At day 50 after exposure, rats were sacrificed and brain sections stained with cresyl violet (general DNA/RNA stain) as well as with anti-albumin antibodies and analyzed for neuropathology (dark neurons) and albumin leakage via common light microscope. Exposure was associated with focal albumin leakage spotted uniformly throughout the brain as well as scattered individual and clusters of dark neurons. The authors report significant neuronal damage, possibly mediated through release of hydrolytic enzymes and other toxic material in cellular organelles. The authors also suggest the age of the rats (12-26 weeks) used in the study may be relatively similar to "cellular phone addicted teen-agers with growing brains [that may be] particularly vulnerable". A similar report at BEMS 2006 in Cancun looked at longer-term exposures using levels of 2 and 200 mW/kg (whole body SAR) once per week for 56 weeks. 3 weeks after the last exposure, rats were assessed using behavior tests. In addition, 14, 28, and 50 days after the last exposure rats were analyzed for dark neuron staining. The authors suggest preliminary results do not confirm earlier reports of neuron degeneration, although there was an indication of albumin leakage in the 14- and 50-day post exposure rats. Recent studies from the same group reported at BEMS 2007 that exposed multiple times over the course of 50 days (as opposed to one time as in initial studies) were not able to repeat the earlier findings of neuron degeneration, but did report short term memory decreases associated with RF exposure. In a subsequent study, the authors exposed Fischer 344 rats to 900 Mhz (GSM) RF for 2 hrs/day, once per week,for 55 weeks at either 0, 0.6, or 60 mW/kg (milliwatts per kg) and tested for cognitive performance using an open field an memory tests. The authors report an effect of RF exposure on memory behavior (impaired memory of objects and their temporal order of presentation) with a possible dose response effect, and conclude the results may indicate long term cumulative effects of GSM exposure. A comment in the same journal by Nordstrom suggested the 1yr old rats may have had retinal atrophy (common in older rats) that may have negatively influenced cognitive performance. These same rats were also evaluated histologically following the memory and behavior testing. Although the authors did not observe evidence of concommitant albumin extravasation (blood brain barrier leakage), dark neuron staining, GFAP expression, lipofuscin aggregation, or signs of cytoskeletal and neuritic neuronal changes of the type seen in human aging in these rats, they suggest this apparent discrepancy might be explained by absorption of damage or physiologic adaptation to the RF insult.
Findings		Effects
Status		Completed With Publication
Principal Investigator		Lund University, Sweden
Funding Agency		NIWL, Sweden
Country		SWEDEN
References		Grafstrom, G et al. Brain Res Bull., (2008) 77:257-263 Nittby, H et al. Bioelectromagnetics, (2008) 29:219-232 Salford, LG et al. Environ Health Persp. , (2003) 111:881-883 Nordstrom, CH Bioelectromagnetics, (2009) 30:508- Nittby, H et al. Bioelectromagnetics, (2009) 30:509-
Comments		It is very difficult to imagine a mechanism that after a single 2 hour, non-thermal exposure at such low SAR (as low as 0.002 W/kg) followed by a 50 day period of equilibration, that rats would still have noticeable BBB leakage, especially in light of studies by Albert 1977, 1979, 1981 and Lin 1982 that showed BBB leakage induced by thermal levels of exposure were quickly reversed. If this is the case, a positive non-RF control should have been incorporated to demonstrate BBB leakage perpetuating itself over a recovery time of 50 days post-insult. There is also no indication of SAR in the brain during exposure, or SAR variability (and with free roaming animals - presumably 4 per TEM cell exposure (?) - there would be marked variability). There is no data suggesting a dose response in the albumin staining between dose groups, and figure 1 does not seem to indicate a dose response in terms of more albumin leakage in the most exterior regions of the cortex – albumin reactive spots are uniformly located throughout the coronal cross-section of brain tissue (it is also no clear what dose group figure 1 is from). Regarding dark neuron staining, there is no correlation with albumin leakage from a dose response perspective. It would have been more appropriate to count the altered neurons, not just to grade them in terms of occasional, moderate, or abundant, especially without stating the range of altered neurons in each category. Apoptotic cell death was mentioned as a possible explanation, but they did not apply readily available stains that would have detected it. It was also not clear that the albumin staining was correlated with the grade of dark neurons. With regards to the examination of brain tissue slides, it is not clear how many areas of each brain (and the size of each area in microns) were examined. There is no score reported for each individual area for comparison. If vacuoles in the neurons were important, why did the authors not produce a photograph of one ? If the dark neurons were apoptotic, there should be no vacuoles within them. If they were not apoptotic, there should have been a reaction (gliosis) to the dead cells. Neither of these things were clarified in the paper. Finally, it is difficult to believe that all "dark" neurons were at the same exact stage of degeneration at the same time 8 weeks after the exposure event for collective analysis and comparison. Although pathological analysis was supposedly performed “blind”, there is no description of how the pathologist performed the study or arrived at his conclusions. No stress control was performed. BBB leakage has been shown to occur following hypertension & seizure (Harik Ann Neurol 1984 Jun;15(6):568-74) as well as with induced models of stress (Belova, Acta Physiol Scand, 1982, 116:21-9), and the pattern of BBB leakage with stress is diffuse throughout the brain, similar to what is shown in figure 1. It might be more reasonable, given the long recovery period, non-thermal RF levels, and the lack of dose response between groups, that a stress at the time of sacrifice induced the changes and not the prior RF exposure - interestingly, the anesthesia used for sacrifice was not named, although it is not certain whether this had any role in the BBB leakage pattern since the sham animals were also presumably given the same drug. There is no description of the distribution of ages of rats in each of the exposed and sham groups. Finally, it is more likely that a 26 week old rat is more similar to a fully mature adult than a teenager (as implied by the authors in the paper) - rats reach adult weight and development at ~3 months.