> Subject: Stray Field Hazards
> Sirs: A recent TV documentary problem has claimed that the mag. field about
> MRI systems can lead to health problems for female operators (i.e.: breast
> cancer) although I have several documents claiming there is no
> hazards(except the routine for pace makers and metal implants) these
> documents are a few years old. Does anyone have any recent documentation
> addressing these issues and can they email copies or addresses from which I
> can get copies from.
>
> Art. J. Ragauskas
>
As you can well imagine, at Bruker we have to follow the subject of
possible negative effects of NMR equipment on health very closely. We are
perfectly aware of studies on the really negative effect of exposure to
electromagnetic fields at microwave frequencies as well as at 50/60Hz
(power lines), and we are also aware that often users do not make enough
distinction between electromagnetic fields and static magnetic fields.
In the case of exposure to pure static magnetic field, the most recent
article known to me is the one published by Juergen H. Bernhardt on the
Deutsches AErzteblatt in December 1991 (D.A 88, Heft 51/52, 23 Dez. 1991),
under the Title 'Biologische Wirkungen statischer Magnetfelder'.
In this article Prof. Bernhardt (Institut fuer Strahlenhygiene des
Bundesamtes fuer Strahlenschutz, Ingolstaedter Landstrasse 1, D-91465
Neuherberg, Germany) states that, except for implants, no know negative
effects could be measured at magnetic fields <2T. For exposure to strong
magnetic fields, as in whole body MRI, no side effects are expected with
field strengths up to 2T for the head, and up to 5T for extremities. At
fields >4T, magneto-electrodynamic and magneto-hydrodynamic effects on the
blood circulation could occur, which might affect patients with heart or
circulation deficiencies. This could lead to high blood pressure. Equally
unknown is the effect on fetuses. Here, wisely enough, Prof. Bernhardt
prefers to stay on the safe side, and he suggests to refrain from
submitting pregnant women to MRI diagnosis, except in unavoidable cases.
A more recent report, in german also, titled `Empfehlungen zur Vermeidung
gesundheitlicher Risiken bei Anwendungen magnetischer Resonanzverfahren in
der medizinischen Diagnostik' has been published on 22 Nov. 1993 by the
`Budesamt fuer Strahlenschutz', i.e. the same organization employing Prof.
Bernhardt. This 60 pages long paper mainly is a recommendation on how to
avoid health hazards in MRI. In this paper some of the misgivings of 1991
relative to the possible effects of magnetic fields >2T are expressed in
somewhat weaker terms.
This seems to be the information that is currently available today.If
anybody has any more recent articles on the subject, especially from the
US, I would be grateful if they could fax them to me.
Just to complete the picture here is a short article on the effect of
Magnetic Pulses, which appeared in the New Scientist No. 2041, 3 August
1996, page 13. I hope New Scientist does not mind me having borrowed these
few lines.
''Magnetic mood
A device that stimulates the brain with painless magnetic pulses to lift the
misery of chronic depression may soon be used in clinics. Neurobiologist
Alvaro Pascual-Leone at the University of Valencia treated 17 depressed
patients, holding the magnet over their scalps in daily sessions of 25
minutes. Eleven patients showed marked improvements lasting up to two weeks.
Neurobiologists believe the magnet works by stimulating brain cells in the
left half of the frontal lobe that are abnormally sluggish in many people
with depression.''
I prefer not to comment on this.
Best regards
Tonio
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Tonio Gianotti Phone: +49 721 5161262
HR NMR Development Fax : +49 721 5161337
Bruker Elektronik GmbH Email: tg@bruker.de
Akazienweg 2
D 76287 Rheinstetten Germany