Power Lines and Magnetic Fields

[VERNIG.PETER@forum.va.gov]

I attended a very interesting Central Rocky Mt. HPS meeting last year
which discussed cancer risk and electrical wiring.  The initial study
that generated the excitment was done in the Denver Metro area.  Because
the investigator either could not get or maybe afford magnetic or electric
field strength measuring devices she devised a wire coding surogate which
essentially expressed the proximety and size of above ground electric
transmission wires to 4 (I think) wire codes. High the number higher the
exposure.  The study found a weak correlation to childhood cancer deaths
(Leukemia I think.  Note some studies dealt with Cancer & some with 
Leukemia
 
Anyway later studies both replicated the wire coding and measured magnetic
field strength.  No correlation to magnetic field strenght was found and
a weak correlation between the wire coding surogate and cancer deaths.
The speaker said E fields had been ruled out but didn't give detail.  He
was and presumably still is studying whether there is a correlation between
cancer and something else besides magnetic fields that correlates to
the wire coding surogate or whether it might be changes in Magnetic
fields that may be the cause.  The field strengths do not stay the same
but vary with the current load and other factors.  It turns out that
older neighborhoods built befor 1970s tend to have high coding since 
buryable cable became available in the early seventies.  Older neighbor-
hoods tend to have metal water piping, be in inner cities, have more
renters and less affluent occupants and a host of other things that might
induce a higher cancer risk.
 
Gentleman also pointed out that it was like trying to show a correlation
between lung cancer and smoking if the baseline were a pack and a half
a day instead of nonsmokers.  That is we are all exposed to the magnetic
and electric fields from power lines to some extent.
 
Anyway thought some of you might be interested although I do not see
powerlines as a biggie as cancer risks go
 
Peter Vernig, VAMC Denver, vernig.peter@forum.va.gov