Lethal effects of microwave on animals has been intensively studied as a candidate for weapon use during the last world war. Here is an example of those experiments [Fly, et al., 1964]. It is considered that the body temperature control system equilibrates to the heat injection by the microwave during phase 2, and phase 3 shows the consequence of the sudden destruction of the body temperature control center in the brain. Eyes Among the animal body tissues, the lens and the testis are most sensitive to excess heat. Both of them have difficulty in being cooled by blood flow because of their relatively scarce blood vessel distribution. Examples about the damage causing threshold (both for irradiation duration and power density of microwave) on the eye (lens), the testis, and the whole body of the dog is shown in Figure 6.4 [Ningen-Kankyoukei ed. group, 1972] In this figure, 3 GHz microwave is used. The damage in the lens is mainly heat induced partial death of cells or protein destruction, i.e., a cataract. Figure 6.4 Relation between Microwave Irradiation Duration and Power Density on the Threshold to Cause Damage in Dog Eye, Testis and Whole Body (f=3 GHz) Results using rabbits whose eye has a similar structure to humans are shown in Figure 6.5. In this Figure 2.45 GHz microwave is used. This is not so different from results using dog. [Information directorate, Department of National Health and Welfare, Canada, 1977,1978] Those results correspond well to theoretical numerical analysis of the eye ball and they show that the temperature threshold to cause cataracts in any part of the lens is 41 °C. There is no report of cataract caused by irradiation of electromagnetic wave less than 0.5 GHz. It is reported that microwaves more than 100 GHz heat the cornea rather than lens.
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