This article is from the Static Electromagnetic Fields and Cancer FAQ, by John Moulder email@example.com and the Medical College of Wisconsin with numerous contributions by others.
The standards are based on several considerations. One objective is to
keep the electrical currents induced by movement through the static
magnetic field to a level less than those that occur naturally in the
body. A second objective is to keep the electrical currents induced in
large blood vessels by blood flow to a level that will not produce
hemodynamic or cardiovascular effects. The pacemaker and prosthetic
device restrictions are considered in Q22.