Space osteoporosis: an electromagnetic hypothesis.

: Loss of body calcium during spaceflight is a potential problem in long voyages. This loss does not appear to be caused by a deficiency in diet or exercise. The idea is advanced that the altered electromagnetic environment experienced in space may be at least partially responsible. We show that the electric field induced inside astronauts because of their motion in the geomagnetic field is greater than that which has produced a wide variety of biological effects in earth-bound experiments.