Michael Coslo wrote:
JB wrote:

If it
weren't for well funded environmental lobbyists,
the FCC wouldn't have been
pressured into cutting exposure limits to half from what was learned by
military studies in the 40's to the 60's and established in the 70's
and cut
to half of that in the 80's and finally made into law for hams and cut in
half again for nervous people who still can't point to anything more
concrete than the old military studies.

There have been lots of studies since then.


I would suggest taking a look at the latest IEEE/ANSI standard for
exposure. The actual limits in the standard only take a few pages. The
other 100 pages is the critical analysis of the hundreds of studies with
respect to every effect one can imagine, and then some.

As Michael points out, there's been a LOT of studies in the last few
years (driving, for instance, a change from field strength limits to SAR
limits in some cases)

What the standard and accompanying analysis makes very clear, though, is
that there is no way to "prove a negative": i.e. there is no way to
"prove" that a particular EM field exposure doesn't have any long term
effects. All you can do is say that there is no known mechanism by
which such an effect can be produced, or that if it does exist, there's
no way to measure it in a statistically significant way, or, in some
cases, that greater exposures have been shown experimentally to have no
moderate term effects (e.g. nobody's done a longitudinal study lasting
30-40 years that's been controlled for other confounding effects).

What you CAN say is that the studies prompting the early alarmist
literature (e.g. "currents of death", "VDTs cause miscarriage") have
severe methodological or statistical problems. Unfortunately, those
early studies have been (poorly) abstracted and summarized many times
and the caveats in the original paper, or subsequent better studies, are
ignored.

Particularly in non-technical trade literature (e.g. trade magazines
aimed at, for example, small business owners), the author of an article
writing about minimizing hazards in the workplace might not actually
know very much about the details of the hazards, nor do a whole lot of
research beyond what's in Wikipedia or copied from some other trade
magazine. They certainly don't go back to the original source, nor do
they look at current standards, etc. I still run across articles that
(indirectly) cite the famous (and totally misinterpreted) Kaiser VDT
study from 1981/1982, published in 1988. While that study found a
correlation, one has to remember correlation is not causation. Someone
googling VDT and miscarriage will no doubt turn up articles in the NY
Times from 1988, for instance, but not pay attention to the fact that
the article is 20 years old, because, on the web, the date is tiny print
and grey.