Microwaves less than 3 cm are absorbed in the outer skin 3 to 10 cm wavelengths penetrate from 1 mm to 1 cm into the skin 25 to 200 cm wavelengths penetrate to deeper tissue and organs Human tissue is transparent to microwaves with wavelengths greater than 200 cm. Absorbed microwaves are converted to heat. Tissue and body temperatures rise, depending on exposure and location exposed. The greatest danger from microwaves is to the eyes, where they appear to have a cumulative effect on the lens of the eyes, ultimately producing cataracts. Cataracts depend on the frequency, power density, duration of exposure and intervals between exposures.
Microwaves effect the central nervous system.
The performance of some cardiac pacemakers is also affected by microwaves. A beneficial use of microwaves is diathermy. These standards are given in various publications prepared by different organizations. Threshold limits are given in Table 1. Microwave threshold limit values.