ID Number		456
Study Type		In Vivo
Model		425, 970, & 2450 MHz (CW) exposure to rats and mice and analysis of immune response
Details		Wistar rats (males) were exposed as follows: 1) 425 MHz (CW) 4 hr/day, 7 days/wk for 20 or 40 days at an SAR between 3.1 and 6.7 W/kg, 2) 2450 MHz (CW) 4 hr/day, 7 days/wk for 40 days at an SAR between 0.7 to 4.7 W/kg), or 3) 970 MHz (CW) 22 hr/day, 69-70 days, at an SAR of 2.5 W/kg. Exposures were performed on both fetal and post-gestational rats using a stripline waveguide (425 MHz), and anechoic chamber (2450 MHz), or individual circularly polarized waveguides (970 MHz). For all exposures, no change in lymphocyte, monocyte, eosinophil, or polymorphonuclear leukocyte, erythrocyte, or leukocyte cell count was observed. In addition, mean cell volume of erythrocytes, hematocrit, and hemoglobin concentration of heparinized blood remained unchanged. For 425 and 2450 MHz (but not 970 MHz) exposures, significant increases in the in mitogen-stimulated (PHA, ConA, pokeweed ag, or E.coli LPS) response of splenic lymphocytes in exposed animals was observed. The authors acknowledged that the results may have been due to a thermally induced stress reaction, although such prenatal exposures may result in a lymphoproliferative response in older rats. In earlier studies, significant increases in complement receptor positive lymphocytes were observed following exposure to 29 W/kg, but this was obviously thermal in nature and other indicators of thermal stress were also observed in the mice. Exposure at 970 MHz elevated serum triglyceride, albumin, and total protein concentration. It was suggested by the authors that the higher serum levels of triglycerides in RF-exposed rats may be a stress-induced response. In other studies, CD-1 mice were exposed to 2450 MHz (CW) RF as fetuses (from day 6 - 18 of pregnancy) for 100 minutes/day at an SAR of 16.5 W/kg. In addition, Balb/C mice (8-10 wks old) were exposed to 425 MHz (CW & PW-1-msec pulse width, 250 pulses/sec) RF for 1 hour/day for 5 days at an SAR of 7.7 W/kg using a rectangular strip transmission line. No growth reduction in exposed offspring was observed. No effect of exposure was observed on antibody response to sheep red blood cells (SRBC), in hemagglutination or hemolysin titers to SRBC, or in isolated lymphocyte response to mitogen stimulation. In a follow-up study, CBA/J mice (9 wks old) were exposed to 2450 MHz (CW) RF for 1.5 hrs/day for 2,3, or 9 days at 3.5, 10.5, and 21 W/g in the far field using an anechoic chamber. Exposure did result in a suppression of NK activity in isolated blood and a decrease in peritoneal macrophage phagocytic activity at the highest SAR, but this was likely due to thermal effects. The effect on NK cells was transient and returned to normal within 24 hr, and was also observed following stress hormone (cortisone) administration. CBA/J mice were also injected with S. typhimurium LPS and exposed to 2450 MHz (CW) RF for 120 minutes at SARs of 3 - 18 W/kg. With exposures during injection above 6 W/kg, the LD-50 dose decreased, although there was no effect with exposure before injection. Exposure to high ambient temperature (37 C) during injection also potentiated the lethal effect of LPS.
Findings		Effects (only at thermal levels)
Status		Completed With Publication
Principal Investigator		EPA, RTP North Carolina, USA
Funding Agency		HPA (NRPB), UK
Country		UNITED STATES
References		Smialowicz, RJ IEEE Eng. in Med. & Biol. Mag., (1987) 6:47-51 Smialowicz, RJ et al. Bioelectromagnetics, (1983) 4:371-381 Smialowicz, RJ et al. Bioelectromagnetics, (1982) 3:467-470 Smialowicz, RJ et al. J. Microwave Power, (1982) 17:211-221 Smialowicz, RJ et al. J. Microwave Power, (1982) 17:121-126 Smialowicz, RJ et al. Bioelectromagnetics, (1981) 2:279-284 Smialowicz, RJ et al. Radio Sci., (1979) 14:147-153 Smialowicz, RJ et al. J. Microwave Power, (1981) 16:73-77
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