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Date:         Fri, 11 Sep 1992 03:38:13 -0700
From:         "R. Allen Gardner" <gardner@EQUINOX.UNR.EDU>
Subject:      Re: Pregnancy and Radiation
Comments: To: Ed Wilds <EHSADM3%UCONNVM.BitNet@pucc.princeton.edu>
Comments: cc: Multiple recipients of list C+HEALTH
              <C+HEALTH%IUBVM.BitNet@pucc.princeton.edu>

It is good that Brad Tidd and Michael Sauda have brought up the
topic of electric blankets.  These are correlated with
significantly increased incidence of miscarriages and infant
cancer.  Consumer Reports November 1989 has a discussion of this
and in a later issue which I have not found yet mentions one
manufacturer that has put out a model with almost no elf.

Michael Sauda also brings up health hazards from alternating
magnetic fields emanating from household wiring which are also
correlated with increased risk of infant cancer.  This and the
electric blanket statistics is really what started interest in
danger from VDT's.

Michael Sauda also brings up the fact that the magnetic field of
the earth is about 500 milligauss.  Reasoning that this must be
the noise factor, most measuring instruments used to start at
higher levels.  This is why there was, initially, a tendency to
scoff at evidence that as little as 300 milligauss increases the
risk of infant cancer.  The critical difference, however, is that
household wiring produces an alternating 60 Herz field.  Quite
independent experiments with chick embryos show that alternating
fields at around 60 Herz and with square waves (just what you get
from the most common household wiring) cause abnormal growth in
chick embryos.  Epidemiological studies must always deal with
correlations, but the chick embryo studies are experimental and
direct.  There are good reasons to be interested in the effects
of magnetic fields on embryonic growth.  This what started the
chick embryo studies, and this is probably why human fetuses and
infants are more sensitive than human adults.

It is good that Michael Sauda could actually cite some figures on
the strength of magnetic fields emanating from common household
appliances.  Note that the figures that he cites for other
appliances are at 4-inches which is closer than most people
usually get to any of the items on his list.  And, note that
human operators rarely spend hours near any of the items on his
list.  Note also that, if danger begins at 300 milligauss, most
of the items on his list produce negligible fields even at
4-inches.  Since the strength of a magnetic field drops at a rate
proportional to the square of the distance from the source,
nearly all of the items on his list produce negligible fields at
the usual distance of human operators.  Unfortunately, the figure
he gives for VDT's is a manufacturers rating without any
indication whatsoever of the distance.  The relatively low
figures Michael Sauda quotes for VDT's are totally useless unless
the distance is known.

The farther the operator can stay from the monitor, the lower the
risk.  I keep my head as far away as possible, but I cannot see
how this helps someone who feels that the foetus in her womb is
is as precious as her own head.

Allen Gardner
University of Nevada
Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU