ID Number		1627
Study Type		In Vivo
Model		915 MHz (GSM), 1500 MHz (PDC) exposure to rats and analysis of blood brain barrier permeability, neuron degeneration, and brain blood flow.
Details		Sprague Dawley rats (adult and juvenile males) (n = 36) were exposed to 1500 MHz (PDC) subchronically (10 minutes) at average brain SARs of 1, 4, or 8 W/kg or chronically (60 minutes/day, 5 days/week, 4 weeks) at 4 W/kg, and analyzed for brain microcirculation changes (vascular diameters, plasma velocities, leukocyte behavior, and BBB function by extravasion of FITC or Na-fluorescein dyes) and age-related sensitivity through an implanted cranial window. A figure-8 shaped loop antenna was used to provide head-first exposure. No significant effects of RF exposure were observed. In a related study, rats were exposed to 915 MHz for 2 hours at SARs of 0, 0.02, 0.2 and 2.0 W/kg in a replication attempt of earlier reports by Salford et al, (Environ Health Perspect (2003) 111:881-883). Rat brains were evaluated at 14 and 50 days post exposure. The authors report no effect on either blood brain barrier permeability or dark (apoptotic) neuron staining. Current studies involve using a cranial window technique and investigating threshold levels of MW exposure required to impact microcirculation and the blood brain barrier integrity. In a related study, cerebro-spinal fluid was examined following dye injection and RF exposure (1.5 GHz at 0.5, 2.2, or 10.3 W/kg for 30 minutes - head first). The authors report no effect of exposure. A 2007 paper reported exposure of rats to 1439 MHz (PDC) for 10 minutes in groups of 0.6, 2.4, and 4.8 W/kg resulted in no blood brain barrier effects, no changes in endothelial adhering leukocytes, and plasma velocity and vessel diameter remained within a normal physiologic range. In a replication attempt of findings from Lund University in Sweden (Salford et al 1992 - 2009), Fisher 344 rats (n = 82) were exposed to 900 MHz (GSM) for 2 hours at 0.02, 0.2, or 2 W/kg and analyzed for BBB permeability by extravasation of serum albumin using immunohistochemistry as well as dark staining for degenerated neurons. The authors report that their studies did not confirm the reports of Salford and Persson. In further studies, rats were exposed to 1.4 GHz (PDC) for at 0.6, 2.4, or 4.8 W/kg (brain average). The authors state that the lowest level approximates exposure levels previously used by Salford et al and the highest approximates ICNIRP local limits. The authors exposed either acutely for 10 minutes or subchronically for 60 minutes/day, 5 d/wk, 4 wks. Rats were examined immediately before and after exposure for blood brain permeability and various microcirculatory changes. Exposure at 4.8 W/kg did elevate temperature in the area under observation by 0.62 degrees C. The authors reported no effects from exposure at any level. AUTHORS' ABSTRACT: Masuda et al. 2015 (IEEE #5964): Little information is available about the effects of exposure to radiofrequency electromagnetic fields (RF) on cerebral microcirculation during rat developmental stages. We investigated whether the permeability of the bloodbrain barrier (BBB) in juvenile and young adult rats was modified during local cortex exposure to RF under non-thermal conditions. The cortex tissue targeted was locally exposed to 1439 MHz RF at an average specific absorption rate of 2.0 W/kg in the target area for 50 min and permeability changes in the BBB of the pia mater were measured directly, using intravital fluorescence microscopy. There was no significant difference in extravasation of intravenously injected dye between exposed and sham-exposed groups of either category of rats. No histological evidence of albumin leakage was found in any of the brains just after the exposure, indicating that no traces of BBB disruption remained. These findings suggest that no dynamic changes occurred in BBB permeability of the rats at either of these development stages, even during local RF exposure at non-thermal levels. AUTHORS' ABSTRACT: Masuda et al. 2015 (IEEE #5966): The aim of this study was to determine whether cerebral microcirculatory parameters in rats were modified during local cortex exposure to a radiofrequency electromagnetic field (RF) under non-thermal conditions. The cortex tissue targeted was locally exposed to 1439 MHz RF using a figure-8 loop antenna at an averaged specific absorption rate of 2.0 W/kg in the target area for 50 min. Three microcirculatory parameters related to cerebral inflammation were measured by the cranial window method in real time under RF exposure. No extravasation of intravenously injected fluorescent dye was observed during RF exposure. There was no significant difference either in pial venule blood flow velocity or diameter between exposed and sham-exposed rats. Histological evaluation for the brain immediately after RF exposure did not reveal any serum albumin leakage sites or degenerate neurons. These findings suggest that no dynamic changes occurred in cerebral microcirculation even during local cortex exposure under these conditions. AUTHORS' ABSTRACT: Ushiyama et al. 2007) (IEEE #5967): AUTHORS' ABSTRACT: Horita et al. 2009 (IEEE #6913): A cranial window method modified for our experiment enabled to observe the cerebral microcirculation including the blood-brain barrier permeability after a local expose to radio-frequency electromagnetic fields with a monopole antenna in rats. The present report reviews our recent publications that reported no noticeable changes in the cerebral microcirculatory parameters due to RF-EMF exposure.
Findings		No Effects
Status		Completed With Publication
Principal Investigator		Nat'l Inst Public Health, Tokyo, Japan - msd@niph.go.jp
Funding Agency		ARIB, Japan, MIC, Japan
Country		JAPAN
References		Masuda, H et al. Radiat Res, (2009) 172:66-73 Masuda, H et al. In Vivo, (2007) 21:563-570 Masuda, H et al. In Vivo, (2007) 21:555-562 Masuda, H et al. in vivo (International Journal of Experimental and Clinical Pathophysiology and Drug Research)., (2015) 29:351-357 Masuda, H et al. in vivo., (2015) 29:207-215 Ushiyama, AC et al. Environmentalist. , (2007) 27:489-492 Kodera, S et al. Int J Environ Res Public Health., (2017) 14:pii: E358. doi: 10.3390/ijerph14040358- Hirota, S et al. Environmentalist., (2009) 29:186-189
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