The Risk of Lymphoma in AKR/J Mice does not Rise with Chronic Exposure to 50 Hz Magnetic Fields (1 μT and 100 μT)

Abstract

Some epidemiological studies suggest that exposure to 50 or 60 Hz magnetic fields might increase the risk of leukemia, especially in children with a comparable high residential exposure. To investigate this possibility experimentally, the influence of 50 Hz magnetic-field exposure on lymphoma induction was determined in a mouse strain that is genetically predisposed to this disease. The AKR/J mouse genome carries the AK virus, which leads within 1 year to spontaneous development of thymic lymphoblastic lymphoma. Beginning at an age of 4-5 weeks, groups of 160 female mice were sham-exposed or exposed to 50 Hz magnetic fields at 1 or 100 microT for 24 h per day, 7 days per week, for 38 weeks. Animals were checked visually daily and were weighed and palpated weekly. There was no effect of magnetic-field exposure on body weight gain or survival rate, and lymphoma incidence did not differ between exposed and sham-exposed animals. Therefore, these data do not support the hypothesis that chronic exposure to 50 Hz magnetic fields is a significant risk factor for developing hematopoietic malignancy.

No effects of GSM-modulated 900 MHz electromagnetic fields on survival rate and spontaneous development of lymphoma in female AKR/J mice

“…Median survival time was 183 (sham-exposed) and 190 days (exposed mice), and not significantly different according to the logrank test, with animals censored which were still alive at the end of the study. Patterns of tumor-related mortality in the sham-control group were consistent with those observed in a previous study conducted in this laboratory with AKR/J mice [32]. As seen in our previous study, essentially all mortality observed in AKR/J mice was related to the development of lymphoblastic lymphomas [33,34] (Figures 7, 8).…”

Approaches to Investigating Complex Genetic Traits in a Large-Scale Inbred Mouse Aging Study

“…Three of the strains were not evaluated because of lymphoma development (AKR/J), confirming a well-documented strain specific phenotype, 70,71 lack of sufficient mice for analysis (CAST/EiJ), or self-mutilations resulting in euthanasia for humane purposes (SJL/J). Therefore, GWAS analyses were performed in 28 strains of mice.…”

“…76 All AKR/J mice died after the 12 months of age exclusively due to development of lymphomas, a known strain-specific lesion due to an endogenous retrovirus. 70,71 All AKR/J mice had structural abnormalities of their hair shafts, unrelated to age, due to a mutation in the Soat1 gene. 24,87 SJL/J fought extensively, especially, but not exclusively the males, requiring many to be euthanized.…”

“…67 By contrast, AKR/J mice are highly prone to lymphomas and rarely survive to 20 months of age with few if any other lesions, a well-known strain characteristic. 70,71 Evaluating mice at standardized ages does provide a cross-sectional profile of all strains at that particular age; however, it is not the best way to determine what diseases are life threatening and potentially the ultimate cause of death in any particular strain. Aging mice, until they become moribund, provide a higher chance of discovering strain-specific disease predisposition and correlating these diseases to mean lifespan.…”

The mouse as a model for understanding chronic diseases of aging: the histopathologic basis of aging in inbred mice

“…All AKR/J mice died prior to reaching this age and thus were necropsied at 12 months of age or in the longitudinal study. In the latter, AKR/J mice developed lymphomas, a known strain-specific lesion due to an endogenous retrovirus (43, 44). All AKR/J mice had structural abnormalities of their hair shafts, which were due to a mutation and unrelated to age (45, 46).…”