|MadSci Network: Medicine|
Do we know whether life could exist without the Earth's magnetic field?
Indirectly, we probably could not survive without the Earth's magnetic field, since the Earth field protects us from cosmic radiation.
There is little evidence that the Earth's static magnetic field has any direct effects at all on humans or on human cells, although bacteria, some fish and possibly some birds and insects use the Earth field for navigation.
Scientists can study the effects of the Earth's static magnetic field in five ways:
Increasing the field: Increasing the intensity of the static magnetic
field has little or no effect on humans or animals until the field strength
gets very high. Here at the Medical College of Wisconsin we have a web site
devoted just to this issue:
Static Electric and Magnetic Fields and Human Health
Reorienting the field: Rorienting the field has no obvious effects on humans, other mammals or mammalian cells. In other words, our body does not seem to know which way North is.
Shielding or nulling the field:The Earth field can be nulled by artificially creating an opposing field that cancels it out. The cancellation is never perfect; for example, Reiper and colleagues (Growth Factors, 13:207, 1996) were "only" able to reduce the Earth's 13-22 microTesla (130-220 milliGauss) field to 0.2 microTesla (2 milliGauss).
Humans, animals or cells can also be shielding from the Earth's magnetic field with a special metal called "mu" metal. Mu metal is very expensive, but it can reduce the Earth field by a factor of 1000 or more.
Experiments done with the Earth field "nulled" are not common, and most of the examples I know of are studies of cells. However, at least one investigator has exposed rats to a null field for up to 4 weeks. In that experiment, Dorofteir and colleagues (Cytobios 84:179, 1995), found only some subtle effects on blood cells.
NASA did some null field studies with humans to see whether the Moon's very low magnetic field would alter behavior. They found no effects.
Space flight: Static magnetic fields in space and on the Moon are very low. This should provide information about the effects of very low fields, but I can find no publications that discuss the issue.
Source: DE Beischer: The null magnetic field as reference for the study of geomagnetic directional effects in animals and man. Annals of the New York Academy of Sciences. 188:324-30, 1971.
Medical College of Wisconsin
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