

How strong would a magnetic field have to be to kill you? - dilap
https://gravityandlevity.wordpress.com/2015/01/12/how-strong-would-a-magnetic-field-have-to-be-to-kill-you/

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simonmd
Radiologist/Biomedical Engineer here. I once did a review of the physiological
effects of magnetic fields as was our current understanding in the last
decade. in general, things that get altered with sufficiently large magnetic
fields: \- Cardiac electrical conductivity \- Muscular electrical conductivity
\- Fibrin (protein necessary for clotting blood) meshes get distorted \- There
is DNA genotoxicity, and mutations start to appear \- Diamagnetic effects
start taking over (Most extreme demonstration I've seen so far is the
levitating frogs and grasshoppers, which seem quite content afterwards, so no
ill effects apparent)

Bottom line is that pretty much everything in our bodies that contains water
can be affected by a sufficiently large static magnetic field. Some critical
physiological processes may get disrupted way earlier than the atomic
distortions cited in the article, so I believe much less than 100k Tesla would
be needed to kill a person.

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TheLoneWolfling
I think that you'd end up with neurological effects before the electrons were
ripped out of atoms. I mean, our nervous system is effectively controlled
ionic exchange.

~~~
swamp40
Here's a video of someone braver than myself experimenting with the effects of
magnetism on his brain while he speaks:
[https://www.youtube.com/watch?v=XJtNPqCj-
iA](https://www.youtube.com/watch?v=XJtNPqCj-iA)

~~~
agumonkey
First this is borderline mad, the shocks sound nasty, second it seems to me
that more than speech is impacted, his whole face stutters.

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jorjordandan
I think you would be killed by the diamagnetic properties of water first...

If you can affect water with a small magnet like this:
[https://www.youtube.com/watch?v=2FvWtEdY4sE](https://www.youtube.com/watch?v=2FvWtEdY4sE)

Then a magnetic field of sufficient power would probably kill you long before
the effects described in the article. I'm amazed that someone other than me
has thought about this!

~~~
VLM
Blood electrocution would get you first. Moving conductor in a magnetic field
generates a current, and you'd just need a current big enough to confuse the
cardiac nerves. Given that existing MRI research magnets can give weird
nervous system feelings when patients wiggle, just an order of magnitude or
two more and you'd get knocked out by your own circulating blood.

~~~
makomk
Don't most of the problems with nerve stimulation in existing MRI systems come
from the gradient coils rapidly modulating the magnetic field, rather than
people moving around?

~~~
loveNanaya
Gradient effects in general:

[http://www.mrisafety.com/SafetyInfov.asp?SafetyInfoID=250](http://www.mrisafety.com/SafetyInfov.asp?SafetyInfoID=250)
[http://professional.medtronic.com/video-
player/index.htm?con...](http://professional.medtronic.com/video-
player/index.htm?contentid=ASSETS_117131&chapnum=2#.VLRCJGTF87M)

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gameshot911
The sci-fi book Blingsight by Peter Watts explores humanity's 1st encounter
with an alien object that contains extremely powerful magnetic fields. Has all
sorts of interesting consequences.

~~~
dghf
Off-topic, but _Blindsight_ kicks ass on any number of levels. Scientifically
plausible vampires! In space! And the only genuinely creepy aliens I think
I've ever come across in fiction.

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sandworm
Has anyone looked at the effects not on particles, but on changes to
reactivity in the presence of magnetic fields? You don't need to rip apart
molecules to kill us. Make certain reactions a little more or less likely to
occur and we stop functioning.

I have seen some discussion of how heavy water could be lethal if it were to
replace all of a body's water based on its very slight differences in
reactivity.

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peter303
Something called Transcranial Magnetic Stimulation alters brain activity at
about one Tesla (10,000x earth's field). TMS has been shown to induce
euphoria, amnesia, and relieve depression. Unclear what stronger magnetic
fields could do. A ten Tesla magnet can levitate a small animal.

~~~
goodbyegti
I work in this sector, and what you say is correct, however it is important to
note that in TMS the fields are pulsed over millisecond time intervals. In
doing so they can induce an electric field which can cause neurons to fire.
The time varience is crucial. A 3T static field from the magnet of an MR
scanner is far less dangerous than a 1T field pulsed in the vicinity of your
brain. That is providing that there aren't any ferromagnetic objects close to
the MR scanner!

~~~
ursidae
Radiologist here. We regularly image patients in 3T MRI scanners. As long as
they don't have certain metal surgical implants, a pacemaker, or metallic
foreign bodies, there is no problem.

Some institutions have research magnets up to 7T:
[http://www.healthcare.philips.com/main/products/mri/research...](http://www.healthcare.philips.com/main/products/mri/research/)

~~~
jkbyc
tattoos can be a problem, right?

~~~
ursidae
Yes, certain inks contain enough metal to cause significant tissue heating.

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Irene
Relatively weak MFs could kill as an indirect result of the injury:
[http://mentalfloss.com/article/18405/mri-magnet-
madness](http://mentalfloss.com/article/18405/mri-magnet-madness)
[http://boards.straightdope.com/sdmb/showthread.php?t=544233](http://boards.straightdope.com/sdmb/showthread.php?t=544233)

The effect depends on field signal characteristics (frequency, amplitude, wave
shape), duration of exposure, genetics and metabolism. Some bacteria can be
negatively affected even by 10 mT. In clinical trials people were "safely"
exposed to up to 3 T.

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mrfusion
Wouldn't iron in blood be affected well before this point though?

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sp332
Bulk iron is ferromagnetic, but many iron-containing molecules are not.
Haemoglobin is not ferromagnetic. [http://www.revisemri.com/blog/2006/mri-
blood-iron-attraction...](http://www.revisemri.com/blog/2006/mri-blood-iron-
attraction/)

~~~
tedunangst
I'd heard that severe haemochromatosis could trigger a metal detector. Is that
just an urban legend?

~~~
sp332
It is paramagnetic, depending on oxygenation, so maybe.

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frozenport
Would you be mechanically compressed by the field before your atoms deform?

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dkirtley
3 Tesla Magnetic field MRI's are now common and I have heard rumors of up to
7T machines in the works:
[http://www.healthdiagnostics.com/svc_hi_field.php](http://www.healthdiagnostics.com/svc_hi_field.php)

~~~
dkirtley
Interesting: ... "scientific research can provide some measure of confidence
that short-term, acute exposures up to about 1-2 T [1000-2000 milliT] should
be safe... However, it is not possible to determine whether there are any
long-term health consequences even from exposure in the milliT range because,
to date, there are no well-conducted epidemiological studies with sufficient
power to be able to come to any conclusion on this, and there are no good
long-term animal studies."

[http://www1.mcw.edu/radiationoncology/ourdepartment/radiatio...](http://www1.mcw.edu/radiationoncology/ourdepartment/radiationbiology/Static-
Electric-and-Magnetic-F.htm#.VLRAGyvF940)

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wallflower
I've always wondered what would happen if you got trapped in the
Superconducting Super Collider.

Terminator 3 Particle Accelerator Scene

[https://www.youtube.com/watch?v=KKFnsFFdPh8](https://www.youtube.com/watch?v=KKFnsFFdPh8)

~~~
PhasmaFelis
We do have an example of a synchrotron researcher who took a proton beam to
his head.
[http://en.wikipedia.org/wiki/Anatoli_Bugorski](http://en.wikipedia.org/wiki/Anatoli_Bugorski)

Surprisingly, he survived, with significant but not disabling neurological
damage.

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mrfusion
I think a lot of new technologies will emerge when we can routinely control
very large magnetic fields. I just think the technological implications are
largely unexplored.

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xorcist
What about semipermiatic structures such as the blood brain barrier? According
to The Internet(tm), permeability in rat brains is affected by a mere 0.1T.

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palakchokshi
So I guess this means we are safe from Magneto :)

~~~
mlrtime
You mean this isn't possible? ;)

[https://www.youtube.com/watch?v=etPXBm0zRvM](https://www.youtube.com/watch?v=etPXBm0zRvM)

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Cricketwcup
earth is a very big magnatic field and it wont kill us. well i think we need a
trillian times stronger magnatic field than earth to kill human.

~~~
deeviant
Earth has a very _big_ magnetic field, but not a very _strong_ one.

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krylon
I've wondered about this exact question for a while now.

If I were to become a lunatic dictator, this is how I would deal with
dissidents. (Disclaimer: I have no intention of ever becoming a lunatic
dictator!)

