Adey WR, Byus CV, Cain CD, Higgins RJ, et al.
In these papers the authors exposed pregnant rats to radiofrequency radiation. Some of the rats were also exposed to a single dose of ethylnitrosurea (ENU), which acts as a carcinogen. The offspring of the rats continued to have far-field RF exposure until weaning at age 21 days and about 10-14 days later they were exposed to near-field radiation (2 hours per day, 4 days per week) that continued until their death or for 2 years.
In the 1999 paper the rats were exposed to a digital 836.55 MHz field with North American Digital Cellular (NADC) pulsed modulation. The rat brain Specific Absorption Rates (SAR) were calculated to be 1.0-1.6 W/kg. There was no evidence of tumour induction from the RF exposure. There was a non-significant trend to inhibition of tumour development.
In the 2000 paper the rats were exposed to a frequency-modulated (FM) signal at 836.55 MHz. The SARs were calculated to be 1.0-1.2 W/kg. There were no effects on incidence of tumours or on survival attributable to FM field exposure in either ENU-treated or in sham-treated groups.
In the second paper the authors discuss possible differences in effects between the two types of signals used in their experiments.