Hi there

This question relates to alternating current electricity, which is at
50hz where I am (in the UK).

I have read that the human "electrical frequency" is around the same,
though I have seen also claims that human frequencies vary from a low
number of Hz to around 300Hz. This seems odd, but is not my question.

My question is: if the frequencies are so similar, does being in an
electromagnetic field from a current source (eg computer, transformer,
pylon) affect the working of the human electrical system in any way?
If so, can you give details of how - e.g. can human electrical pulses
be affected so that they don't travel the noemal distance or what?

Regards

electricquestion-ga


 There is no technical term such as ' human "electrical frequency" ' ,

 however, if we want to find  some meaning to it, we may consider 

  EEG and EKG waves, emg waves which are produced inside the body and
can be measured outside.

 EEG shows the electrical activity of neurons in the brain.

http://www.sciencenewsforkids.org/.../ Feature1.asp

http://www.stat.uiuc.edu/~ombao/eeg.html

 EKG show what the heart is doing.
http://www.guidant.com/condition/heart/heart_signals.shtml


The spectrum (showing which frequencies are present) is given here in 
Fig 1a.  (see the peaks at  5 Hz and 15 Hz)


http://www.sccn.ucsd.edu/ ~scott/pca95.html

Different peaks have names ( alfa, beta ..) and their intensity changes with
activity (sleep, meditation,...) 

or disease  (epilepsy)

http://www.acm.org/conferences/sac/sac2000/Proceed/FinalPapers/BC-07/

Epileptic fit can be induced by outside stimuli - not by electric wave -
but by the light flashes (of course, light is an emg wave - but that's
not that you are asking, I think)

The reason why electromagnetic field (= emg) does not affect inside
function of neurons, why it does not affect their electric signalling,
 is as follow:

Human body is conductive. Dry skin is not a good conductor - but inside the skin
people are 'wet'  and water solutions are conductive. This conductive layer
forms a Faraday cage - a shield which does not allow the emg waves to penetrate
too deep.
http://en.wikipedia.org/wiki/Faraday_cage

http://www.rfsafe.com/research/rf_radiation/shielding_rf_hazards/faraday_cage.htm

http://unitedstatesaction.com/emp_and_faraday_cages.htm

 Naturally, that depends on frequency and intesity : High frequency
and intensity may pass through (e.g. X rays).

Higher frequency (20kH to GHz)  (radio frequencies) have less and less
biological effect (expect for heating if intensity is very high (such
as in the microwave oven)

Very High frequencies (UV, X ray,  gamma rays) may be dangerous. 

The full emg spectrum is shown here
 http://www.yorku.ca/ eye/spectru.htm


For example, UV light exposure can cause cancer of the skin (is genotoxic).
http://www.ehealthmd.com/library/melanoma/MEL_causes.html

The reason why scientists are confident about where the boundary between harmles
and dangerous radiation is, can be deduced from the Quantum Mechanics: Photon 
(a particle of emg radiation) has to have certain minimal energy (frequency) to
be able to break a chemical bond. That minimal frequency starts at UV. Microwave
radiation (used by cell phones) is softer and cannot change biomolecules.

Technical explanation is here:

http://www.eng.uc.edu/~gbeaucag/Classes/XRD/Chapter1html/Chapter1.html


In spite of the expert consensus that biological effects of waves 
from cell phones, high voltage power lines, ... are negligeable, there
is substantial lay literature asserting the opposite:

This example, (which looks impressive) asserts  'Genotoxicity': 

Substances that damage cellular genetic material, such as DNA and
chromosomes, are called "genotoxic".

http://www.feb.se/EMFguru/EMF/genotoxic/Genotoxic-EMR-paper.htm


Common sense rebutal to these persistent alegation is this:

AC electricity came to widespread use during 1850 -1920 . Since that time most
people live in a 50Hz (or 60Hz) emg radiation bath from the household wiring.
 No significant ill-effects have been observed so far. There have been
many claims of that, but no evidence.
 http://www.acnem.org/journal/pdf_files/21-1_april_2002/21-1_cancer_trends_during_the-20th_century.pdf.




Hedgie

Very helpful answer. Thank you

I think this is one of those things that is on the fringe (unproven scientifically).

There have been numerous health studies to date.  For example:

http://www.arpansa.gov.au/is_emf.htm

The Controversy Over Electromagnetic Fields and Possible Adverse Health Effects

Such claims are akin to the therapeutic magnets on the market today.
Our body does not react to magnetic fields, however magnetic fields do
influence it because of the water content, if our body would react to
magnetic fields being in an MRI would mean excruciating pain.

Bioelectric fields are so weak that they are almost impossible to
measure with current technology you can read about it on
http://www.springerlink.com/content/6176336481p7611x/fulltext.pdf
in addition 
"While conceptually simple, a number of factors
can cause serious measurement errors. This communication
describes a system consisting of two lock-in amplifiers
along with ancillary circuits which are useful in the
frequency range from approximately 5 Hz to 1 MHz in
biologic tissue with dissipation factors up to approximately
200"
so you see, in measuring bioelcetric fields the margin of error in the
(best case scenario) is as of today four times greater than the hz
used in household electricity. All those claims of human 'electric
frequency' being anywere from 50 to 400 Hz are within that margin of
error. So, technically, they are all correct.