>>>>>>
Does anyone know of any studies on the impact of mri or nmr spectrometers
(magnets or rf) on pregnancy? I have been told that OSHA might have
commissioned a study on mri's and pregnancy. Does anyone know of this
study and where I can get a copy of the results?
Are there any concerns in this area relative to Oxford magnets or the small
Varian magnets?
>>>>>>
Several very helpful responses were received. I am summarizing these
responses below. Thanks to those who responded.
Doug Lowman, Eastman Chemical Company, dwlowman@KODAK.COM
>>>>>>>
RESPONSES:
Can't say I know of the study.
However, I know of numerous NMRists-come-mothers, who had nothing abnormal
happen during their pregnancy, or afterwards.
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Ross Mair Email: rmair@stan.xx.swin.oz.au
NMR Lab Snail: Mail 41, Swinburne University,
Applied Chemistry Dept PO Box 218, Hawthorn, 3122.
Swinburne University of Technology Fax: +61-3-8190834
Hawthorn, Victoria, Australia Voice: +61-3-8198843
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1. With regard to rf. There must be some regulations among the OSHA rules
on electronics, but I have not managed to get them from our safety people.
2. Magnets. I've been told by a safety person and verified this with Varian
(approximately 6 months ago) that there are no rules currently, just guidelines. The guidelines can be
found in an American Conference of Governmental Industrial Hygenists article
"1990-91 Threshold Limit Values for Chemical Substances and Physical Agents
and Biological Exposure Indices". Also, one of our graduate students was
told to stay away from high magnetic fields by her obstetrician when she was
pregnant.
Aidan Harrison
Director, NMR Facility
Chemistry Department
Cornell University
Ithaca, NY 14853
Tel: (607) 255-7593
FAX: (607) 255-4137
e-mail: harrison@chemres.tn.cornell.edu
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Having just jumped through the FDA's hoop for application for an
"Investigational Device Exemption" for our 4 T / 170 MHz whole-body magnet,
which involved a fairly exhaustive literature search on side-effects of
high magnetic fields on humans (and animals), I can say with some
confidence that no such study has been published in the open literature.
There are a couple of possibly relevant pieces of information:
1) The trade periodical "mr" published by Miller Freeman Publications, 600
Harrison St., San Francisco, CA 94107, recently published a "sidebar" in
which a "survey" conducted by them of female workers in clinical MRI
facilities was mentioned.
2) There are a couple of articles on the effect of high magnetic fields on
reproduction in mice or other rodents. No effects were found. See:
B.Zimmermann, D. Hentschel, Digit. Bilddiagn. 7, 155 (1987), Georg Thieme
Verlag, Stuttgart-New York. Also: B.D.Tunggal, K. Hofmann, W. Stoffel, K.
Oette, H. Diekmann, M. Walger, H. von Wedel, Naturwissenschaften, 79, 512
(1992).
In case you are interested, FDA will soon issue new guidelines indicating
that exposure of human subjects or patients to static fields up to 4.1 T is
considered "non-significant risk" for research or clinical purposes
(formerly 2.0T).
Carl Gregory
Biomedical Magnetic Resonance Laboratory
University of Illinois
Urbana, IL 61801
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I have on my desk, a book called Biological Effects and Safety Aspects of
Nuclear MAgnetic Resonance Imaging and Spectroscopy. It was published by the
New York Academy of Sciences in March of 92. It is the proceedings of a
conference on the same subject. I do not know if the book is available
to non-members, or if it is still in print.
I read it when I first got it, and I don't remember reading anything that
alarmed me.
Some random quotes:
...data still preliminary... negative against any statistically signifigant
elevations of spontaneous abortion rates, infertility, low birth weight, and
premature delivery... (page 216)
...pregnant personnel are advised that ..no known data to suggest ...any..
harm experienced by exposing the fetus to the static magnetic field...due to
lack of data we recommend that pregnant personnel not be exposed to
time-varying RF or gradient megnetic fields of the imaging system (pg 217)
reference: Kanal, Shellock, Savitz, 1991, Survey of reproductive health among
female MR operators; Abstract at 77th meeting Radiological Society of North
America (Chicago, 1-6 December 1991).
Exposure of mice to about 1 T in utero has had no effect on prenatal or
postnatal development. (pg 377) Ref: Sikov et al. 1979 Development of mice
after intrauterine exposure to direct-current magnetic fields. 18th Hanford
Life Sciences symposium, Richland, WA , Oct 1978 Konermann and Monig 1986
Studies ...static magnetic fields on prenatal development of mice Radiologe
26:490-497
...some equivocal data suggesting developing chick embryo is sensitive to
prolonged exposure to weak ELF magnetic fields... results from mammalian
studies are mostly negative... such exposure does not seem to affect
chromosome structure... (pg 381)
pg 384 discusses the well-know effects of high maternal body temperature on
fetal development, and suggests this may be a concern due to RF heating.
I remember, but cannot find, a reference toa study that breed several
generations of mice in a static field with no problems.
Final note: I recently had a baby, and I was more concerned about exposure to
chemicals of known and unknown toxicity from student samples than I was about
exposure to the magnets.
Karen Ann Smith kasmith@iastate.edu
Chemical Instrument Services (515) 294-4057
Iowa State University Ames, IA 50011
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Karen Smith wrote
> I have on my desk, a book called Biological Effects and Safety Aspects of
> Nuclear MAgnetic Resonance Imaging and Spectroscopy.
> ...
> I remember, but cannot find, a reference toa study that breed several
> generations of mice in a static field with no problems.
Karen's note reminded me of an anecdote I heard in the early 60's, when iron-
core electromagnets were the only game in town. One research worker put some
mice in a cage between the pole pieces of a magnet, turned the field on, and
started observing. After a few weeks, he realized that the reproduction rate
of the mice had dropped to zero! He was all ready to publish a paper on this
startling discovery, when someone pointed out that the pole pieces of the
magnet were too close together to permit total freedom of movement by a _pair_
of mice, even though any _individual_ mouse could easily move around under the
low ceiling of the cage.
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Gerald A. Pearson INTERNET: gerald-pearson@uiowa.edu
Chem. Dept., Univ. of Iowa VOICE: 319-335-1336
Iowa City, IA 52242-1219, USA FAX: 319-335-1270
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