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  #1  
Old 09-22-2006, 12:51 PM
Spoke Spoke is offline
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Effect of Strong Magnets on Human Body

Given that there is iron in the human body, and particularly in human blood, I have sometimes wondered what effect a strong magnetic field would have on the human body. Would it exert any pull on red blood cells? Would it be hazardous in any way? Do people who work near strong magnets run special risks or take special precautions?

I tried googling an answer but couldn't find my way past all the goofy pseudoscience on the magical healing powers of magnets.

So what's the straight dope?
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  #2  
Old 09-22-2006, 12:56 PM
Beaucarnea Beaucarnea is offline
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I have been in a full body MRI twice a year for the past 7 years. I have seen no improvement. In fact, the degree to which I suffer clausterphobia has gotten markedly worse.

"howstuffworks" has a great explanation of how the machine produces images.
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  #3  
Old 09-22-2006, 01:27 PM
rowrrbazzle rowrrbazzle is offline
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A thread from a few months ago: Super-strong magnets... deadly?
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  #4  
Old 09-22-2006, 01:44 PM
Nuclear_Siafu Nuclear_Siafu is offline
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Quote:
Originally Posted by spoke-
Given that there is iron in the human body, and particularly in human blood, I have sometimes wondered what effect a strong magnetic field would have on the human body. Would it exert any pull on red blood cells? Would it be hazardous in any way? Do people who work near strong magnets run special risks or take special precautions?

I tried googling an answer but couldn't find my way past all the goofy pseudoscience on the magical healing powers of magnets.

So what's the straight dope?

Well, if you get a strong enough magnet you can change the orbits of your electrons, and bring about an effect called "diamagnetic levitation" provided you keep your magnetic fields in equillibrium. The up-shot is that you can do cool things like levitage frogs. The frogs don't seem to mind it so, theoretically, you could do the same with any organic matter without ill effects, proivided you had a magnet powerful enough.

I think the real danger to people from high power magnets comes not from tissue damage, but from foreign objects implanted in the body (steel plates, bolts, shrapnel, etc.) getting torn loose.
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  #5  
Old 09-22-2006, 02:22 PM
Squink Squink is offline
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Quote:
Originally Posted by spoke-
Would it exert any pull on red blood cells?
Not much. Most biological iron is too finely divided to form the magnetic domains required for ferromagnetism.
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  #6  
Old 09-22-2006, 02:27 PM
Squink Squink is offline
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Now if you apply strong magnetic fields to a part of the body that has electrical activity, such as the brain, you can get some interesting effects: Transcranial magnetic stimulation
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  #7  
Old 09-22-2006, 02:30 PM
spingears spingears is offline
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Quote:
Originally Posted by Squink
Unless I am mistaken it is in solution as ions, not as metalic iron, and therefore not affected by magnetic fields.
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  #8  
Old 09-22-2006, 02:32 PM
gazpacho gazpacho is online now
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Quote:
Originally Posted by Nuclear_Siafu
Well, if you get a strong enough magnet you can change the orbits of your electrons, and bring about an effect called "diamagnetic levitation" provided you keep your magnetic fields in equillibrium. The up-shot is that you can do cool things like levitage frogs. The frogs don't seem to mind it so, theoretically, you could do the same with any organic matter without ill effects, proivided you had a magnet powerful enough.
When people worry about the effect of strong magnetic fields they tend to be worried about more about long term effects. Like say an increase in the risk of cancer etc. The frog levitation just shows that it probably won't kill you quickly.
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Old 09-22-2006, 03:03 PM
Nuclear_Siafu Nuclear_Siafu is offline
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Quote:
Originally Posted by gazpacho
When people worry about the effect of strong magnetic fields they tend to be worried about more about long term effects. Like say an increase in the risk of cancer etc. The frog levitation just shows that it probably won't kill you quickly.

I suppose that's a reasonable concern. Still, any theoretical physics experiment you can walk away from...
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  #10  
Old 09-22-2006, 03:04 PM
Squink Squink is offline
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Quote:
Originally Posted by spingears
Unless I am mistaken it is in solution as ions, not as metalic iron, and therefore not affected by magnetic fields.
Most iron in the body is bound to something, rather than floating around in solution as free ions. Rather than trying to enumerate the charge state of all those different species, it's sufficient to note that the largest one, arrays in ferritin, is too small to exhibit ferromagnetism.
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  #11  
Old 09-22-2006, 03:11 PM
AskNott AskNott is offline
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In a small percentage of test subjects, there's a tendency to sleep facing north for a night or two.
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  #12  
Old 09-22-2006, 04:19 PM
Crafter_Man Crafter_Man is offline
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I'm not too concerned about strong DC magnetic fields (such as those produced by permanent magnets) and very low frequency fields (e.g. 60 Hz). High frequency magnetic fields are more worthy of concern, IMO.
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  #13  
Old 09-22-2006, 04:31 PM
CurtC CurtC is online now
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Quote:
Originally Posted by gazpacho
When people worry about the effect of strong magnetic fields they tend to be worried about more about long term effects. Like say an increase in the risk of cancer etc.
While I agree that people tend to worry about that, the OP was asking about actual effects.
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  #14  
Old 09-22-2006, 04:34 PM
Spoke Spoke is offline
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I would be interested in both immediate and long-term effects, if any.

Thanks for the responses, everyone.
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  #15  
Old 09-22-2006, 08:43 PM
Rysdad Rysdad is offline
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I work with a number of MRI techs who've held their jobs for a number of years with no ill effects.

Funny thing, though...they never get lost.

Kidding. Just kidding.
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  #16  
Old 09-22-2006, 09:02 PM
David Simmons David Simmons is offline
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Quote:
Originally Posted by AskNott
In a small percentage of test subjects, there's a tendency to sleep facing north for a night or two.
Baloney. The tendency is to sleep facing south, except when there is a full moon.
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