SPS MICROWAVE HEALTH AND ECOLOGICAL EFFECTS - PROGRAM AREA OVERVIEW Dan i el F. Cah i11 Exp. Biol. Div., U.S. Env. Protection Agency, Res. Triangle Park, NC 27711 The Reference System for SPS proposes to employ microwaves as the means by which power will be transmitted from the satellite to ground-based rectenna sites. An operating frequency of 2450 MHz CW is considered optimum at this time because this frequency has relatively low atmospheric transmission losses, is not allocated as a broadcast frequency in the U.S., and the technology exists to mass produce power amplifiers for this frequency. The necessity for considering the potential microwave health and ecological effects of the SPS is based on the anticipated power levels which the SPS will radiate. It is expected that the maximum ground level power density would be 23 mW/cm2 at the center of a 10 by 13 kilometer rectenna and 1 mW/cm2 at its edge. Beyond the controlled area of the rectenna site the power densities would range from tens of pW/cm2 to nW/cm2. The resultant exposure scenarios are: occupational exposures of adult male and female workers to 0.1-23 mW/cm2 on an intermittent basis; brief, transient exposures of members of the general public and airborne biota to levels of 0.1-23 mW/cm2; continuous exposure of the general population, comprised of all age groups and various states of health, to .0001-0.1 mW/cm2; continuous exposure of on-site ecosystems to 0.1-23 mW/cm2 and off-site ecosystems to .0001-0.1 mW/cm2. Public acceptance of the SPS is crucial to the viability of the concept. This can only be gained if a number of important issues are addressed and satisfactorily answered. Not the least of these are the potential microwave health and ecological effects (MW/H/E). Because of the short timeframe allotted to the Concept Development Phase of the SPS program, the MW/H/E area was necessarily focused on two near-term objectives, the need to investigate those apparently credible reports of biological effects occurring at 2450 MHz which had not yet been corroborated and an examination of specific questions resulting from the operation of an SPS system. As a result, SPS-sponsored research was directed at establishing dose-response relationships and threshold levels for the effects of relatively short term exposures at moderate to low power densities (1-23 mW/cm2) on birds and bees and on the hematological/ immunological, teratological and behavioral responses of mammals. The current status of this research will be presented. The Ground Based Exploratory Research Phase of the SPS program will provide the time for an evolution of the MW/H/E program. The general direction of the research program during this period will be discussed. A considerable amount of health effects research is conducted at a frequency of 2450 MHz outside of the SPS program. Some recent research results which may have implications for the SPS program will be briefly reviewed. These include the reports of: Thomas et al. on microwave/drug interaction; Stern et al. on behavioral thermoregulatory response to microwaves; Adair and Adams on autonomic thermoregulation; Lovely et al. on behavioral and biochemical effects of low level exposures and the Johns Hopkins report on the health status of employees at the U.S. Embassy in Moscow.
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