Oberto G, Rolfo K, Yu P, Carbonatto M, et al. (2007)
In 1997 Repacholi and colleagues reported a two-fold increase in non-lymphoblastic lymphoma in Pim1 transgenic mice exposed for two 30 minute periods per day for 18 months to 217-pulsed 900 MHz RF fields. An Australian study by Utteridge et al. (2002) failed to replicate these findings. The study of Oberto et al., part of the PERFORM A program of the Fifth Frame-work European program, is another attempt to replicate the results of Repacholi et al. Oberto et al. used improved dosimetry, different exposure levels, replaced necropsied mice with tissue-equivalent phantoms, and performed necropsies "on-site" both for animals that died and for those that survived up to termination of the study.
A total of 500 Pim1 mice, 50 per sex per group, were exposed, sham-exposed, or used as cage controls. Three exposed groups were used, at whole-body SARs of 0.5, 1.4, or 4.0 W/kg. They were exposed at 900 MHz frequency (pulse width 0.557 ms, pulse repetition rate 217 Hz) for 1 hour per day, 7 days/week, for 18 months. The study was blind.
The study did not show any effect on the incidence of tumours at any site, and therefore the results of Repacholi et al. could not be confirmed. The authors suggest that the results of Repacholi et al. were likely due to an unexpectedly low incidence of lymphomas in their control group. Repacholi et al. reported that 22% of their controls had lymphomas while Oberto et al. found tumours in 44 % of their sham-exposed group and in 52% of their cage controls. Utteridge et al. also found a higher incidence of tumours in their controls than did Repacholi et al.