This article is from the Static Electromagnetic Fields and Cancer FAQ, by John Moulder email@example.com and the Medical College of Wisconsin with numerous contributions by others.
51) E Kanal, FG Shellock & L Talagala: Safety considerations in MR
imaging, Radiology 176:593-606 (1990).
Eight area of potential concern in MRI safety are reviewed. "It may
be safely concluded that although no deleterious biological effects from
the static magnetic fields used in MRI have been definitively associated
with this modality, all the facts are by no means in yet, and further
research is continuing..."
52) International Non-Ionizing Radiation Committee of the International
Radiation Protection Association: Protection of the patient undergoing
a magnetic resonance examination, Health Phys. 61:923-928 (1991).
For the static magnetic-field the IRPA guideline is to monitor
cardiovascular status above 2000 mT, and not exceed 10,000 mT. "The
scientific literature does not indicate adverse effects from exposure of
the whole-body to 2 T and of the extremities to 5 T".
53) JF Schenck: Health and physiological effects of human exposure to
whole-body four-Tesla magnetic fields during MRI, Ann. NY Acad. Sci.
"Although no health abnormalities were noted [in preclinical trials of
4000 mT MRI units], there were several instances of mild sensory
effects... A strong argument can be made that the potential hazards of
these effects up to field strengths of 4 T [4000 mT] are well below
thresholds set the stability of human tissue..."
54) G Miller: Exposure guidelines for magnetic fields, Amer. Indust.
Hygiene Assoc. J. 48:957-968 (1987).
The Lawrence Livermore static magnetic field exposure guidelines, with
a detailed review of the bioeffects data and of the basis for the
standard. Guidelines: at 1 mT, exclude pacemakers and warn those with
prosthetics; at 50 mT, training and medical surveillance are required,
and those with sickle cell anemia are excluded; 2000 mT is the peak
55) FS Prato et al: Blood-brain barrier permeability in rats is
altered by exposure to magnetic fields associated with magnetic
resonance imaging at 1.5 T, Micro. Res. Tech. 27:528-534 (1994).
Exposure of rats to MRI conditions or to a 1500 mT static field
increased blood-brain barrier permeability. "The effect of MRI on
blood-brain barrier permeability is poorly understood... additional
experiments are needed to understand the importance of static field, RF
field and gradient field".
56) K Schulten: Magnetic field effects in chemistry and biology, Adv.
Solid State Phys. 22:61-83 (1982).
"Chemical and biological photoprocesses which involve bimolecular
reactions between non-zero spin intermediates... can be influenced by
magnetic fields". The examples discussed all involve field strengths of
at least 1 mT, and generally over 10 mT.
57) JC Scaiano et al: Model for the rationalization of magnetic field
effects in vivo. Application of the radical-pair mechanism to
biological systems, Photochem. Photobiol. 59:585-589 (1994).
A model is proposed for magnetic field effects in biological systems.
The model involved effects on the chemistry of radical pairs. The
result of the magnetic field is to increase the life-time and hence the
concentration of free radicals.
58) National Radiation Protection Board: Restrictions on human
exposure to static and time varying electromagnetic fields and
radiation, Document of the NRPB 4 (5):1-69 (1993).
The basic restrictions for static magnetic fields are 5000 mT maximum
to limbs, 2000 mT maximum to whole body and 200 mT averaged over 24
hours. For static electric fields the maximum is 25 kV/m.
59) Documentation of Threshold Limit Values, American Conference of
Government Industrial Hygienists, Cincinnati, OH, (1994).
The static field standard is that "routine occupational exposures
should not exceed 60 mT (600 G) whole body or 600 mT (6000 G) to the
extremities on a daily, time-weighted basis... A flux density of 2 T
[2000 mT] is recommended as a ceiling value.
60) Environmental Health Criteria 69, Magnetic Fields, World Health
Organization, Geneva, Switzerland, (1987).
"from the available data it can be concluded that short-term exposure
to static magnetic fields of less than 2000 mT does not present a health