Changes in the dielectric properties of rat tissue as a function of age atmicrowave frequencies

The dielectric properties of ten rat tissues at six different ages were mea sured at 37 degreesC in the frequency range of 130 MHz to 10 GHz using an o pen-ended coaxial probe and a computer controlled network analyser. The res ults show a general decrease of the dielectric properties with age. The tre nd is more apparent for brain. skull and skin tissues and less noticeable f or abdominal tissues. The variation in the dielectric properties with age i s due to the changes in the water content and the organic composition of ti ssues. The percentage decrease in the dielectric properties of certain tiss ues in the 30 to 70 day old rats at cellular phone frequencies have been ta bulated. These data provide an important input in the provision of rigorous dosimetry in lifetime-exposure animal experiments. The results provide som e insight into possible differences in the assessment of exposure for child ren and adults.