New research indicates that prolonged exposure to low-level magnetic fields such as those emitted by common household electronic devices causes DNA damage to rat brain cells. The research shows further that damage from brief exposures appears to build up cumulatively over time. Exposure to a 60-hertz field for 24 hours appears to result in significant DNA damage. After 48 hours, rats showed even more breaks in DNA strands. Exposure resulted in a marked increase is cell apoptosis, or "cell suicide," a process by which cells self-destruct when they are unable to repair themselves. A previous study showed similar damage but used shorter exposures at 10 times the intensity. The recent study shows that even lower intensities can bring about cumulative effects that are more significant than short high-intensity exposures. Traditionally scientists have held that low-level EM fields were not harmful because they could not break chemical bonds in a living organism. While this may be the case, the recent research may suggest that instead of breaking chemical bonds directly, EM exposure may induce a different process in cells that causes damage indirectly. In any case, this is very significant research given the tremendous sea of EM energy we are all now living in.