The effect on body weight in mice of lifetime exposure to power frequency electromagnetic fields

These studies assessed the effect of chronic exposure to a 60 Hz circularly polarized electromagnetic field (EMF) on the general health, cancer incidence, body weight and body composition of a large cohort of mice. Female C57BL/6 mice received lifetime exposure to either an EMF flux density of 1.42 mT for 18h/day, or an ambient EMF of 0.13 μT. Beginning on the first day of EMF exposure, 1710 mice were treated with one of three levels of split-dose Cobalt-60 γ-radiation (cumulative 3.0, 4.0, or 5.1 Gy). The remaining 570 mice received sham irradiation treatment. Lifetime incidences of hematopoietic neoplasia were similar in all experimental groups. Chronic exposure to EMFs did not affect the mortality incidence rates. An effect of EMF exposure on body weight was observed at 10 age intervals (P ≤ 0.001) and for ionizing radiation at 28 age intervals (P ≤ 0.001). Mice exposed only to EMF exhibited ≤0.5g greater weight gain relative to sham-exposed controls (P = 0.0001). Body composition of aged mice from the terminal sacrifice was determined by dual-energy x-ray absorptiometry, using the Lunar PIXImus2 densitometer. Mean values for total body bone mineral density, total body bone mineral content, lean mass, fat mass and percent fat were not significantly different in EMF exposed and unexposed mice. Correlation coefficients of individual body weights and body weight difference from baseline values with individual fat mass values were significant for both EMF exposed and unexposed mice. However, these relationships were more strongly correlated among exposed mice (P < 0.0001), and the differences in correlation coefficients for EMF exposed and unexposed mice were statistically significant (P < 0.05). The strong association between body weight and fat parameters suggests a likely role for increased fat mass as a determinant of greater body weight gain during 28 months of EMF exposure. These study results indicate that some not yet identified effect of EMF exposure was responsible for the significant differences in body weight, which for aged mice was correlated to increased fat mass. This also suggests that EMF exposure may be one factor in the modern environment that is contributing to the loss of instinctive weight control in human populations.