Uncertainty evaluation of an in vivo near-field exposure setup for testing biological effects of cellular phones

In designing an in vivo near-field exposure setup for testing biological effects of cellular phones, one generally uses a small still animal because a plastic holder is used to restrain it. One also takes no account of the exposure box with radio wave absorbers as well as the plastic holder. In this paper, for the in vivo exposure setup developed in the National Institute of Information and Communications Technology (NICT), which was used for testing the promoting effect of 1.439- and 1.95-GHz digital cellular phones on rat brain carcinogenesis, we investigated the effects of the above-mentioned factors on the dosimetry design using the finite-difference time-domain (FDTD) method in conjunction with an anatomical rat model. As a result, we found that the specific absorption rate (SAR) averaged in the brain was 18% higher at maximum than the previously designed level due to the existence of the exposure box and the plastic holder and that the variation due to the rotation of the rat's head inside the plastic holder was within 10%. The backward movement of the rat along the plastic holder was more serious, which yielded a decrease of nearly 20% for the average SAR in the brain.