The 1.5 GHz electromagnetic near-field used for cellular phones does not promote rat liver carcinogenesis in a medium-term liver bioassay

We have recently established that local exposure to a 929.2 MHz electromagn etic near-field, used for cellular phones, does not promote rat liver carci nogenesis in a medium-term bioassay system. In the present study, a 1.439 G Hz electromagnetic near-field (EMF), another microwave band employed for ce llular phones in Japan, was similarly investigated. Time division multiple access (TDMA) signals for the Personal Digital Cellular (PDC) Japanese cell ular telephone standard system were directed to rats through a quarter-wave length monopole antenna, Numerical dosimetry showed that the peak SARs with in the liver were 1.91-0.937 W/kg, while the whole-body average specific ab sorption rates (SARs) were 0.680-0.453 W/kg, when the time-averaged antenna radiation power was 0.33 W. Exposure was for 90 min a day, 5 days a week, over 6 weeks, to male F344 rats given a single dose of diethylnitrosamine ( 200 mg/kg, i.p.) 2 weeks previously At week 3, all rats were subjected to a two-thirds partial hepatectomy, At week 8, the experiment was terminated a nd the animals were killed. Carcinogenic potential was scored by comparing the numbers and areas of the induced glutathione S-transferase placental fo rm (GST-P)-positive foci in the livers of exposed (48) and sham-exposed rat s (48), Despite increased serum levels of corticosterone, adrenocorticotrop ic hormone (ACTH) and melatonin, the numbers and the areas of GST-P-positiv e foci were not significantly altered by the exposure. These findings clear ly indicated that local body exposure to a 1.439 GHz EMF, as in the case of a 929.2 MHz field, has no promoting effect on rat liver carcinogenesis in the present model.