A REVIEW OF EFFECTS OF SPS-RELATED MICROWAVES ON REPRODUCTION AND TERATOLOGY Ezra Berman U.S. Environmental Protection Agency (MD-72) - Experimental Biology Division Health Effects Research Laboratory - Research Triangle Park, N.C. 27711 During the next few minutes, I will be discussing the effects of microwaves on the reproductive system in mammals. In this talk, I will attempt to gather the diverse work in this general area, represented by approximately sixty articles, abstracts, contract reports, and other scientific publications describing experiments conducted at frequencies from 300 - 30,000 MHz. Because this audience is so diverse in its background and training, and because competent scientific reviews of this area have been made, I will not present a detailed review of the reproductive effects of microwaves. Instead, my purpose is to discuss some of the problems to be encountered in an evaluation of SPS-related microwaves as an influence on human health, and to present the problems so that this diverse audience can more easily appreciate the expected difficulties. The areas of reproductive function that I will discuss are: teratology, where the fetus is treated while in the dam and the fetus is then examined for alterations; and male reproductive functions, such as sperm production. The study of the reproductive effects of microwaves began about 20 years ago. The intervening years have resulted in approximately 100 reports of studies. Fortunately, a good portion of these studies have been conducted at the frequency relevant to this symposium, 2450 MHz. But, too frequently many of the reports contain little more than the author's interpretations of the data; what is needed are more reports containing clear descriptions of experimental conditions, materials, methods, and experimental results. During the last five years, the field of investigations into the reproductive effects of microwaves has matured with scientific discipline. The USSR literature has left us with a legacy of inadequately described experiments of reproductive effects. The scientists in that country, though, have lately begun to describe their experiments more adequately. Therefore, we can expect in the future a growing number of reports of scientific quality in the field of microwave reproductive toxicology. I have noted that experiments in reproductive toxicology have been conducted at frequencies from 300 MHz to 30 GHz. It may appear that some of this range of frequencies does not have any relevance to human exposure at 2450 MHz. But there are ways in which these experimental data can be made more relevant to teratologic evaluations. There are 2 reasonable concepts which describe the absorption of microwave energy into the body: the model of relative absorption rates, and the model of resonance. We can use these 2 models to attempt to extrapolate possible effects from one species to another, and from one frequency to another. Resonance can be simplified for this context to mean the most efficient absorption. The frequency- of-resonance is that frequency at which the most efficient absorption occurs in a specific body size. For instance, the mouse is resonant at 2450 MHz; the rat at 1000 MHz; and man has the most efficient absorption at approximately 100 MHz. (Figure 1.) Along with the relationship of body size and resonance, is the relationship of body size with the distribution of energy. (Figure 2.) When the body size and the wavelength are approximate, energy deposition is non-uniform. At frequencies where the body size is smaller than the wavelength, the distribution is uniform. And, when the body is larger than the wavelength, the distribution of energy is surface directed. We can see, then, that there can be great differences in ab-
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