Eμ-Pim1 transgenic mice expressing a dysregulated Pim1 oncogene in their lymphoid cells were used to test whether exposure to 50 Hz magnetic fields can increase the frequency of malignant lymphoma in mice of a strain predisposed to develop such tumors spontaneously at low incidence. Specific-pathogen-free female mice were allocated randomly into groups of approximately 100 at 6-8 weeks of age and then exposed for 20 h/day for up to 18 months to sinusoidal magnetic fields of 0, 1, 100 or 1000 μT, or 1000 μT pulsed 15 min on and 15 min off. Additional Eμ-Pim1 mice were injected with ethylnitrosourea (50 mg/kg body weight) as positive controls for enhanced lymphomagenesis; these yielded a cumulative incidence of lymphoma of 60% in 9 months. A lethal, transgene-dependent renal glomerular disease occurred at a frequency that varied from 9% to 19% among the groups, but the increase was statistically significant only at the 1000-μT exposure. Lymphoblastic and non-lymphoblastic (predominantly follicular) lymphomas were seen in 26 to 35% of the exposed mice, but at no significantly higher incidence than the 29% found in the sham-exposed mice. Hence we conclude that the lymphoma-prone mice did not reveal any tumorigenic effect of long-term exposure to 50 Hz magnetic fields.
A Test of Lymphoma Induction by Long-Term Exposure of Eμ-Pim1 Transgenic Mice to 50 Hz Magnetic Fields
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Alan W. Harris, Antony Basten, Val Gebski, Denise Noonan, John Finnie, Mary L. Bath, Michael J. Bangay, Michael H. Repacholi; A Test of Lymphoma Induction by Long-Term Exposure of Eμ-Pim1 Transgenic Mice to 50 Hz Magnetic Fields. Radiat Res 1 March 1998; 149 (3): 300–307. doi: https://doi.org/10.2307/3579964
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