Biological effects of radio frequency electromagnetic fields (EMF) on the blood‐brain barrier (BBB) have been studied in Fischer 344 rats of both sexes. The rats were not anaesthetised during the exposure. All animals were sacrificed by perfusion–fixation of the brains under chloralhydrate anaesthesia after the exposure. The brains were perfused with saline for 3–4 minutes, and thereafter perfusion fixed with 4% formaldehyde for 5–6 minutes. Whole coronal sections of the brains were dehydrated and embedded in paraffin and sectioned at 5 µm. Albumin and fibrinogen were demonstrated immunohistochemically and classified as normal versus pathological leakage. In the present investigation we exposed male and female Fischer 344 rats in a Transverse Electromagnetic Transmission line chamber to microwaves of 915 MHz as continuous wave (CW) and pulse‐modulated with different pulse power and at various time intervals. The CW‐pulse power varied from 0.001 W to 10 W and the exposure time from 2 min to 960 min. In each experiment we exposed 4–6 rats with 2–4 controls randomly placed in excited and non‐excited TEM‐cells respectively. We have in total investigated 630 exposed rats at various modulation frequencies and 372 controls. The frequency of pathological rats is significantly increased (p < 0.0001) from 62/372 (ratio: 0.17 ± 0.02) for control rats to 244/630 (ratio: 0.39 ± 0.03) in all exposed rats. Grouping the exposed animals according to the level of specific absorbed energy (J/kg) give significant difference in all levels above 1.5 J/kg. The exposure was 915 MHz microwaves either pulse modulated (PW) at 217 Hz with 0.57 ms pulse width, at 50 Hz with 6.6 ms pulse width or continuous wave (CW). The frequency of pathological rats (0.17) among controls in the various groups is not significantly different. The frequency of pathological rats was 170/481 (0.35 ± 0.03) among rats exposed to pulse modulated (PW) and 74/149 (0.50 ±0.07) among rats exposed to continuous wave exposure (CW). These results are both highly significantly different to their corresponding controls (p <0.0001) and the frequency of pathological rats after exposure to pulsed radiation (PW) is significantly less (p < 0.002) than after exposure to continuous radiation (CW).
E.N. Albert, Light and electron microscopic observation on the blood-brain barrier after microwave irradiation, in: Symp. on Biol. Eff. and Measur. of Radiofr/Micowaves, FDA 77-8026, ed. D.G. Hazzard (HEW Publications, Washington, DC, 1977) pp. 294–304.
E.N. Albert, D.L. Brainard, J.D. Randall and F.S. Janatta, Neuropathological observations of microwave irradiated hamsters, in: URSI Int. Symp. Biol. Eff. Electromagn. Radiat. (URSI, Helsinki, 1978) p. 58.
E.N. Albert and S. Mahmoud, Morphological changes in cerebellum of neonatal rats exposed to 2.45 GHz microwaves, in: Electromagnetic Fields and Neurobehavioral Function, eds. M.E. O'Connors and R.H. Lovely (Alan R. Liss, Inc., New York, 1984) pp. 135–152.
Y. Ashani, F.H. Henry and G.N. Catravas, Combined effects of anticholinesterase drugs and low-level microwave radiation, Radiat. Res. 84 (1980) 496–503.
M.L. Crawford, Generation of standard EM field using TEM transmission cells, IEEE Trans. Elecromagn. Compat. 16 (1974) 189–195.
Dacopatt, Handbook of Immunochemical Staining Methods (1994).
H.J. Garber, W.H. Oldendorf, L.K. Brown and R.B. Lufkin, MRI gradient fields increase brain mannitol space, Magn. Reson. Imaging 7 (1989) 605–610.
H. Goldman, J.C. Lin, S. Murphy and M.F. Lin, Cerebral permeability of 86Rb in the rat after exposure to pulsed microwaves, Bioelectromagnetics 5 (1984) 323–330.
J.W. Hand, Biophysics and technology of electromagnetic hyperthermia, in: Methods of External Hyperthermia Heating, ed. M. Gautrie (Springer, Berlin, 1990) pp. 1–59.
J.C. Lin, Engineering and biophysical aspects of microwave and radiofrequency radiation, in: Hyperthermia, eds. D.J. Watmough and W.M. Ross (Blackie and Son, Glasgow, 1986) pp. 42–75.
J.C. Lin and M.F. Lin, Studies on microwave and blood-brain barrier interaction, Bioelectromagnetics 1 (1980) 313–323.
J.C. Lin and M.F. Lin, Microwave hyperthermia-induced blood-brain barrier alterations, Radiat. Res. 89 (1982) 77–87.
L. Martens, J. Van Hese, D. De Zutter, C. De Wagter, L. Malmgren, B. Persson and L.G. Salford, Electromagnetic field calculations used for exposure experiments on small animals in TEM-cells, Bioelectrochemistry and Bioenergetics30 (1992) 313–318.
J.H. Merritt, A.P. Chamness and S.J. Allen, Studies on blood-brain barrier permeability after microwave radiation, Radiat. Environ. Biophys. 15 (1978) 367–377.
A. Mihaly and B. Bozoky, Immunohistochemical localization of serum proteins in the hippocampus of human subjects with partial and generalized epilepsy and epileptiform convulsions, Acta Neuropathol. 127 (1984) 251–267.
V. Nair and L.J. Roth, Efffect of X-irradiation and certain other treatments on blood-brain barrier permeability, Radiat. Res. 23 (1964) 249–269.
J.P. Neilly and J.C. Lin, Interaction of microwaves on the blood-brain barrier of rats, Bioelectromagnetics 7 (1986) 405–414.
C. Neubauer, A.M. Phelan, H. Kues and D.G. Lange, Microwave irradiation of rats at 2.45 GHz activates pinocytic-like uptake of tracer by capillary endothelial cells of cerebral cortex, Bioelectromagnetics 11 (1990) 261–268.
W.H. Oldendorf, Permeability of the blood-brain barrier, in: The Nervous System, ed. D. Tower (Raven Press, New York, 1975) pp. 229–289.
K.J. Oscar and T.D. Hawkins, Microwave alteration of the bloodbrain barrier system of rats, Brain Res. 126 (1977) 281–293.
F.S. Prato, J.R.H. Frappier, R.R. Shivers, M. Kavaliers, P. Zabel, D.J. Drost and T.Y. Lee, Magnetic resonance imaging increases the blood-brain barrier permeability to 153-gadolinium diethylenetriaminepentaacetic acid in rats, Brain Res. 523 (1990) 301–304.
E. Preston and G. Prefontaine, Cerebrovascular permeability to sucrose in the rat exposed to 2450 MHz microwaves, Appl. Physiol. Respir. Environ. Exercise Physiol. 49 (1980) 218–223.
E. Preston, E.J. Vavasour and H.M. Assenheim, Permeability of the blood-brain barrier to mannitol in the rat following 2,450 MHz microwave irradiation, Brain Res. 174 (1979) 109–117.
S.I. Rapoport, Blood-Brain Barrier in Physiology and Medicine (Raven Press, New York, 1976).
L.G. Salford, A. Brun, J. Eberhardt, L. Malmgren and B. Persson
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Persson, B.R., Salford, L.G. & Brun, A. Blood‐brain barrier permeability in rats exposed to electromagnetic fields used in wireless communication. Wireless Networks 3, 455–461 (1997). https://doi.org/10.1023/A:1019150510840
- Electromagnetic Field
- Continuous Wave