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EMF: exposure vs. dose vs. nonsense
Dear Richard , Ruth and all:
The discussion of the potential health effects of electromagnetic fields
breaks down immediately on the constructs EXPOSURE and DOSE. What does it
mean to be "exposed" to a magnetic field? What is a "dose" of magnetism?
We HP-types talk about exposures all the time in relation to ionizing
radiation. Exposure to ionizing radiation refers to an observed effect: the
production of ions in the exposed substance. Similarly dose refers to the
transfer of energy per unit mass of the substance receiving the dose. What
are the equivalent constructs in reference to magnetic fields? It is NOT
the field strength vector (H = B/mu) or the flux density vector (B). These
are mathematical constructs that assign a set of three numbers to points in
space surrounding a magnet. What observable effect in the "exposed"
substance is being measured when we talk of exposure to a magnetic field?
Also remember that a magnetic field is NOT a form of radiation (not even the
non-ionizing type).
To say that one is exposed to a 4mG field is equivalent to saying that one
was exposed to 4 mCi of radiation. The result is literally nonsense.
Clayton J. Bradt, CHP
Principal Radiophysicist
NYS Dept. of Labor
Radiological Health Unit
voice: (518) 457-1202
fax: (518) 485-7406
e-mail: usccjb@labor.state.ny.us
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