What's on the walls--400 lab / stlenc-heads


Previous Home Next

 No Harmful Physical Effect


This was GE NMR's first foray into "Far Side"-like cartoons.  Apparently GE's lawyers contacted Gary Larson, the cartoonist
who drew "Far Side," about doing these; he said he was not interested in doing them himself but had no objection to them copying
his style.  Since many "Far Side" cartoons were about scientific subjects, it seemed very appropriate.  This cartoon was printed on
hot pink T-shirts which were distributed at ENC.  (Unfortunately mine wore out a long time ago.)  This image was taken from a
postcard that was also distributed at the meeting.
The subject of how electromagnetic fields affect living organisms has been controversial.  A few years ago, there was a lot of press
about epidemiological studies that were said to demonstrate a link between the fields surrounding high-voltage power lines and
the incidence of cancer.  More recent studies have not shown the same linkage.  The static magnetic fields surrounding NMR
magnets are not generally thought to cause any effects.  OHSA rules permit people to work full shifts with a limb exposed to
magnetic fields of several hundred gauss, which in our magnets is only present inside the bore of the magnet.  To have an MRI scan in
a normal hospital scanner operating at 60 MHz or so, you have to be in a much higher magnetic field, more than 10,000 gauss.  I
have had one, and found it to be unpleasantly claustrophobic, but it didn't cause me any other symptoms.  People who have been
in very strong imaging magnets, operating at 400 MHz, have reported having transient symptoms such as a metallic taste in
their mouths.  These high field systems are only used in research applications, not for routine diagnosis.