[Occupational risk among magnetic resonance workers. Analysis of the literature].

It was observed that "medical diagnosis utilizing Magnetic Resonance (MR) scanners may be one of the first modalities in which there is more risk for the operator of the equipment than for the patient" (Young, 1984). Despite this statement, only a few studies have been devoted to the assessment of occupational hazard in MR imaging personnel. The principal features associated with MR systems are: static magnetic fields, time-varying magnetic fields, and radiofrequency irradiation. Potential medical effects related to these hazards are reviewed. Static magnetic fields are known to induce in vitro changes in enzyme kinetics, orientation changes of macromolecules and subcellular components, distortion of ion currents and magnetohydrodynamic effects. Possible mechanisms for static magnetic field bioeffects include the exertion of magnetic forces, the induction of voltages, and other mechanisms (proton tunneling, ion cyclotron resonance) that are yet scarcely known. Human epidemiological studies on static magnetic fields are mainly based on subjective observations, and lack adequate control for confounding factors. Time-varying magnetic fields in the extremely-low frequency range have been associated with both occupational and non-occupational adverse health effects. Exposure to electromagnetic fields in office workers has been related to an increased rate of abortion; the vast majority of studies in this field, however, did not reach any significant result. Many literature reports support the evidence of an elevation of cancer risk in subjects exposed to residential and occupational ELF fields. Although such observations are not yet proved, the alleged occupational risk in magnetic fields exposure should induce to optimize exposure in MR imaging workers.