Chronic toxicity oncogenicity evaluation of 60 Hz (power frequency) magnetic fields in B6C3F(1) mice

A 2-yr whole-body exposure study was conducted to evaluate the chronic toxi city and possible oncogenicity of 60 Hz (power frequency) magnetic fields i n mice. Groups of 100 male and 100 female B6C3F(1), mice were exposed to pu re, linearly polarized, transient-free 60 Hz magnetic fields at flux densit ies of 0 Gauss (G) (sham control), 20 milligauss (mG), 2 G, and 10 G; an ad ditional group of 100 male and 100 female B6C3F(1), mice received intermitt ent (1 hr on/1 hr off) exposure to 10 G fields. A small bur statistically s ignificant increase in mortality was observed in male mice exposed continuo usly to 10 G fields; mortality patterns in all other groups of mice exposed to magnetic fields were comparable to those found in sex-matched sham cont rols. Body weight gains and the total incidence and number of malignant and benign tumors were similar in all groups. Magnetic field exposure did not increase the incidence of neoplasia in any organ, including those sites (le ukemia, breast cancer, and brain cancer) that have been identified in epide miology studies as possible targets of magnetic field action. A statistical ly significant decrease in the incidence of malignant lymphoma was observed in female mice exposed continuously to 10 G fields, and statistically sign ificant decreases in the incidence of lung tumors were seen in both sexes e xposed continuously to 2 G fields. These data do not support the hypothesis that chronic exposure to pure, linearly polarized 60 Hz magnetic fields is a significant risk factor for neoplastic development in mice.