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04 July 2009

Answer to Question #376 Submitted to "Ask the Experts"

Category: Consumer Products

The following question was answered by an expert in the appropriate field:

Static field magnets used as medical therapy: Magnetic appliques are available from a variety of stores that place magnetic fields from 500 to 1000 Gauss in close proximity to head, neck, lumbar, eyes, joints, etc. These appliques are even in the form of mattresses, on which people may lie for many hours per day. What are the potential health effects of such "therapies" after many months or years of exposure? An informative Web site is that for Nikken Corporation.

The strength of magnetic fields is measured in units of Tesla (T), where 1 T is equal to 10,000 gauss. The earth's geomagnetic field strength is about 0.5 gauss or 5 x 10^-5 T. Magnetic field exposure recommendations have been published for occupational exposure, for wearers of medical electronic devices, and for Magnetic Resonance Imaging (MRI) patients, as follows:

Current recommendations of the American Conference of Governmental Industrial Hygienists (ACGIH) are that worker exposure to static B fields should not exceed 60 millitesla (mT) (600 gauss) to the whole body and 600 mT (6000 gauss) to limbs, on a daily time-weighted basis, and short term exposures should not exceed 2 T (20,000 gauss) to the whole body and 5 T (50,000 gauss) to limbs.
Wearers of medical electronic devices such as pacemakers should be limited to 0.5 mT (5 gauss) fields.
The U.S. Food and Drug Administration (F.D.A.), Center for Devices and Radiological Health (CDRH) has established a guidance level for static magnetic fields of 4 T (40,000 gauss), above which MRI studies could present risk to patients.

The above recommendations are not directly applicable to medical therapy applications. For these situations it might be best to consult your private physician for guidance.

Gary H. Zeman, ScD, CHP
Lawrence Berkeley National Laboratory

Answer posted on 27 July 2000. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of materials and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.