Abstract

Small pieces of guinea-pig skin were exposed to a uniform field of microwaves at χ-band (8,730 MHz). Measurements showed that 26% of the incident energy was reflected, 34% was absorbed, and the remaining 40% was transmitted. Absorbed energy was converted to heat, causing a rise in the temperature of the skin. After exposure to microwaves the skin was maintained in vitro on a nutrient medium. Uptake of radioactive substances from the medium into skin constituents was measured. A graded reduction in the uptake of sulphate ions into chondroitin sulphate, proline into collagen, and of phosphate into phospholipid, nucleic acid, and phosphoprotein fractions was found. The incident energy density causing 50% reduction of all these biochemical activities was approximately 4,750 mJ./sq. cm. under the thermal conditions of the experiment. The cooling rate of the tissue is important in determining the effect of microwaves.