ID Number		501
Study Type		In Vivo
Model		435, 2450 MHz (CW) exposure to pigs and hamsters and analysis of blood brain barrier permeability
Details		In an initial study, 200-lb pigs (n=15) were fitted with a leather harness holding a standard two-way portable radio (Motorola, Model MX350, 452 MHz, 6.4 W) and irradiated 8 hr/day for 90 days with a peak brain SAR of 8.1 W/kg. Animals were injected with Evans Blue dye 1 hr prior to sacrifice. No evidence of blood-brain barrier disruptions, brain edema, or brain injury was observed. In subsequent studies, Chinese hamsters were exposed to 2450 MHz (CW) microwaves for 2 hours at a SAR of 2.5 W/kg in the far field. Initial findings showed hamsters injected with horseradish peroxidase immediately after exposure had significant blood brain barrier leakage in the pons, cerebellum, areas around the fourth ventricle, and thalamus. Minor leakage was also detectable in the hypothalamus, hippocampus, and cerebral cortex. At the ultrastructural level, increased HRP reaction product in pinocytotic vessicles was observed in exposed animals, as well as platelet aggregation and perivascular edema. Animals allowed to recover for 2 hours following exposure, however, had minimal blood brain barrier leakage showing the reversibility of the effect. Related studies by Tsurita (2000) and Balzano (1982) using slightly different animal models, however, could not validate these findings of leakage immediately following exposure and the initial studies were interpreted as probably due to thermal artifacts.
Findings		Effects (only at thermal levels)
Status		Completed With Publication
Principal Investigator		George Washington Univ, Washington D.C., USA
Funding Agency		Motorola
Country		UNITED STATES
References		Sutton, CH et al. J. Microwave Power, (1982) 17:280-281 Albert, EN et al. Brain Res., (1981) 230:153-164 Albert, EN Radio Sci., (1979) 14:323-327 Albert, EN et al. J Microw Power, (1977) 12:43-44 Albert, EN Symposium on Biological Effects and Measurement of Radio Frequency/Microwaves. Proceedings of an FDA Conference, D.G. Hazzard, editor. HEW Publication (FDA) 77-8026., (1977) :294-304
Comments		In the pig study, SAR information was not included in the paper, but was obtained via personal communication with Q. Balzano.