Fifty-Hertz magnetic field exposures of premature infants in a neonatal intensive care unit.
In this study the magnetic flux density in and around incubators of a neonatal intensive care unit was registered and mapped. The mean 50-Hz magnetic flux densities in an incubator were typically in the range of 0.2-1 microT, with maximum values around 1.5 microT. For 1 incubator, harmonics contributed to the field substantially. The field levels varied depending on the type of equipment, the positioning of the electronics and the position of the 240-volt main plugs. The positioning of the infant in the incubator and the precise mattress position in the incubator affected the magnetic flux density to a great extent, as did the positioning of the electronic monitoring and treatment equipment. The flux density values found were fairly low as compared to magnetic field levels present at some work places where high electric currents are used. In intensive care units, however, the duration of exposure can be very long, especially for premature infants. The fields can also be compared with the magnetic field levels of residences and are then approximately 100 times higher. Further studies are necessary -it seems important to record magnetic fields and attempt to reduce the levels. Such a reduction can be achieved by reducing the field from the incubators but also by changing the electronic equipment around the incubators or increasing the distance to the incubator. Further research should of course also study any mechanism by which magnetic fields can affect cells and organisms. Compared to the risks many of these infants are exposed to, it is difficult to say whether the magnetic field levels measured can represent a significant additional risk factor. However, this is an area where one should adopt a prudent avoidance strategy, particulary considering how easily these fields can be reduced, mainly through redesign of the various equipment.
Aasen
S E
SE
Department of Physics, University of Trondheim, Norway.
Johnsson
A
A
Bratlid
D
D
Christensen
T
T
D004781:Environmental Exposure; D006801:Humans; D007185:Incubators; D007231:Infant, Newborn; D007234:Infant, Premature; D007363:Intensive Care Units, Neonatal; D008280:Magnetics; D010789:Phototherapy / Q000295:instrumentation