An evaluation of the biological effects of three different modes of magnetic fields on cultured mammalian cells.

The biological effects of static magnetic fields, and their combined effects with ionizing radiation, were studied using a cultured mammalian cell line (FM3A). The three different modes of magnetic fields evaluated in this report were the 0.3 Tesla (T) field with a gradient of 0.3T/m, the 0.7T field with a gradient of 0.7T/m and the 6.34T field with no gradient. Exposure to the 0.3T and 0.7T fields had no effect on cell survival. Exposure to the 6.34T field decreased cell survival. Survival curves showing the combined effect of the 0.3T and 0.7T fields with radiation had a smaller mean lethal dose (D37) value. The survival curve of the 6.34T field was influenced by the interval between magnetic exposure and ionizing irradiation. When the interval was 6 or 12 h, the survival curve showing the combined effect of the 6.34T field had smaller D37 and quasithreshold dose (Dq) values, indicating the potentiation of the radiation effect. Flow cytometric analysis indicated that exposure to the 0.3T and 0.7T fields showed no change and that exposure to the 6.34T field showed an increase in the percentage of G1 phase cells. Our conclusions were as follows: 1) magnetic fields decreased the colony-forming abilities of cultured mammalian cells; 2) magnetic fields can affect the cell cycle; 3) a stronger magnetic field strength does not always have stronger biological effects and 4) the gradient of a magnetic field may be an important factor when combined with ionizing radiation. Despite the foregoing analysis, the biological effects of magnetic fields on mammalian cells remains a complex phenomena.