Conference 7.286::digital

>military ELF radars

You can't do radar with ELF.  ELF is used to send very low-rate data (orders
of magnitude slower than 110 baud) to submarines.

/john

       RE: .1
       
       	Sounds just like the ELF we in DEC use.. :-)
       
       							mike

    Although when you consider the amount of power it takes to put out ELF
    it is phenominal. When I did my time at Beavertail point xmtr site in 
    Rhode Island we used to have an elf transmitter. This mitter utlizied 
    wave guides instead of cable. So its not the frequency that causes the
    radiation but the means of transmitting the frequency.
    
                            Mike

    Re: [.1]: I was imprecise.
    
    The series of articles discussed the PAVE-PAWS installation on Cape
    Cod, which electronically switches its microwave signal around the sky
    at tremendous speed.  I don't have the articles handy (I'm circulating
    them), but I recall there was a harmonic at 73 hertz, which is in the
    ELF range.
    
    When Cape Cod residents expressed concern about the signal, Air Force
    scientists assured them that the power radiated by the installation was
    so low that being injured was no more likely than "getting a suntan by
    moonlight."  However, they measured the AVERAGE power, not the PEAK
    power.  They also said, in effect, that no harmful effects were known,
    because no one had looked for them, because none were expected.  Cape
    Cod residents would thus be experimental animals, but it was OK,
    because the Air Force didn't intend to check the results...
    
    Since the installation has been operating, independent epidemiological
    studies have been conducted, and they have indeed turned up a slight but
    distinct rise in cancer rates around the site.
    
    The mechanism by which ELF radiation causes harm is not well
    understood, but it is not related simply to the power being absorbed by
    living tissues.  It is related to the frequency, and, unfortunately, 60
    hertz is a bad frequency.
    
    One further comment on the potential magnitude of this problem: A
    power-company researcher, while disagreeing with the studies,
    nonetheless was quoted as saying that if they were valid, then it could
    be extrapolated that ten to fifteen percent of all childhood cancers
    were being caused by man-made electromagnetic radiation.

This is one of the basic problems that many people refuse to acknowledge. 
Everytime I talk about it, people just laugh. But its a demonstratable
phenomenon. If you can place a floppy disk in front of a CRT (I used a
VT terminal to try this) and then experience data errors after putting the disk
back in the diskette drive and trying to read it, think what those fields 
are doing to your brain - probably mutating neurons or some other subtle
effect. I've gotten headaches from sitting near a PDP-11/70 too long,
along with all the attendant disk drives. 

Hopefully LCD screens will reduce the CRT problem, but other sources of
EMF continue to pollute our living "space". No one in business wants to
acknowledge the problem, but then it's not visible is it. I hope some
sort of cheap Geiger counter becomes available to measure this invisible
danger.

erik

    I can't believe this stuff won't go away.  60-hertz radiation has
    been with us since the turn of the century.  It's probably close
    to impossible to study it's effects on humans because there are
    no non-radiated control groups around.  It's also true that those
    areas where electricity is in heavy general use are those where
    the life-expectancy of the population is highest.  Yes, this is
    from other factors, but you probably can't get one without the other.
    
    Given the option of dying of electrically-induced cancer at age
    77 or dying from purely 'natural' causes at the ripe old age of
    34, I'll pick the former.
    
    As to headaches from machines.  The odds are hundreds to one that
    the noise rather than the electrical radiation is what's bothering
    you.  Background noise can be very disturbing and tension-causing 
    for some people.  
    
    As to floppy disks being damaged by CRT magnetic fields - of course
    they are.  I for one, however, still use bio-chemical neurons. 
    I just can't get into those new-fangled magnetic human memories.
    
    On the other hand, I've been able to fully recover data from floppies
    which have had Tequila spilled all over them which is more than
    I can say for myself.
    
    Don

what has that got to do with DIGITAL - that is the name of this conference, 
isn't it???

Bruce

>                            -< Interesting but... >-
>
>what has that got to do with DIGITAL - that is the name of this conference, 
>isn't it???

	  It has everything to do with our working environment. I
	thought that was obvious.

	Roy

    (First in a string of commentaries..
    re .0, Steve:
    
>    We live and work in a sea of electromagnetic radiation, a byproduct of
>    our electrically powered, electronically enhanced civilization. 
>    Current moving through a conductor produces both an electric field,
>    which radiates into space, and a magnetic field, which arcs around onto
>    itself.
    	Last part only valid for DC.  As noted in yoru first sentence, what
    	leaves is an electromagnetic field, both components.
    
    >If the source is alternating current, the fields oscillate around some
    >fundamental frequency.  Electrical fields can be shielded using Faraday
    >cages (essentially metal enclosures), but magnetic fields cannot be
    >stopped from permeating everything around them.
    	Last part simply not valid.  Magnetic shielding is standard
    	technology.  Iron, etc provide magnetic shielding.  Specialized
    	alloys provide better.  Once frequencies get up to "radio"
    	essentially any conductor shields both the "E" and "M" field.
    
    >A few researchers have chosen to study the effects, if any, of these
    >fields.  And studies have shown small, but consistent, effects on
    >living creatures.
    	Some studies have shown effects, not all.  Studies (or experiments)
    	in this area are notably difficult to do.
    
    >Significant sources of this subtle radiation include high-tension power
    >lines,
    	Power lines do not "radiate" effectively.  Effects, if any, are
    	localized.
    
    >electric blankets,
    	These actually are the highest sources for the genral public at
    	"ac power" frequencies.
    
    >military ELF (extremely low frequency),
    	(as pointed out already, ELF is NOT used for radar.)  There
    	are other users of ELF than the military, though not many.
    
    >radars,
    	Radar, as genrally used is in a very different frequency range from
    	the other sources cited.
    
    >and the vertical-refresh circuitry of video display terminals.  These
    >emissions have been implicated in health problems such as childhood
    >cancer, adult cancer, and miscarriages.
    	The key word, for me, is "implicated".  Much more needs to be done
    	to have any certainty.
    
    >This problem has been documented in a series of articles in The New
    >Yorker entitled "Annals of Radiation: The Hazards of Electromagnetic
    >Radiation."  The articles appeared in the June 12, 19, and 26 editions
    >this year.  I found the articles long (seventy-five pages total) and
    >the reading slow, but the further I got, the more convinced and
    >disturbed I became.  When a high-ranking official of the Environmental
    >Protection Agency in the Reagan (laissez-faire) Administration states
    >in a professional conference that he would not move his children into
    >a house near a high-tension line, even if it cost $25,000 more to 
    >live elsewhere, you have to take the studies seriously.
   	I don't, at least til I have read them.  Being a government
    	official doesnt grant him any particular technical expertise.
    
    >I suggest that anyone with access to these articles check them out. 
    >I'd be interested to hear the opinions of others on this subject.
    	I intend to.
    
    ====================================================================
    Personal comments:
    I have been following this field with some attention for some years.
    There is much work which should have been done, which should BE done.
    I work in related areas, and with some knowledge in those areas
    The whole issue is an easy one to get lost in.
    
    There is a lot of "bad science" done in this area.  One (widely
    quoted) study tried to correlate cancer rates with how much electrical
    energy the study team "thought" was flowing on the power line in the
    neighborhood (standard distribution, not high voltage line).  The study
    claimed to find a positive effect, but hadn't checked the _KNOWN_
    presence of chemical hazardous wastes, to see how that would effect
    their study.
    
    Even the "language" is confusing, with "radiation" having multiple
    uses for reasonably separate phenomona.  A few points:
    
    	Human life span has increased, roughly propotional to the use
    	of electrical power.  If there were a strong negative effect,
    	it would have been noted.
    
    	I have heard it said, knowledgably, that essentially all Cancers
    	can be attributed to _known_ mechanisms relating to certain
    	chemicals, nuclear radiation, and viral infections.
    
    Two interesting cases (not statistically valid, but interesting):
    	Nikola Tesla invented what became the foundation of our modern
    	AC power distribution system involving the use of high voltage.
    	He followed that up by experimenting with high voltages in 
    	what we now call the ELF and LF regions of the radio spectrum.
    	He died in his 90's (no reference material handy...).
    
    	Thomas Edison also spent a lifetime working with electricty.  He
    	lived to a similar age.
    
    More to follow
    
    thanks
    dave pierson

    If this topic is beginning to get you worried, here's some more for you
    to worry about.  In most, if not all, DEC offices, there are numerous
    devices installed which, unknown to many employees, emit
    ELECTROMAGNETIC RADIATION with a wavelength somewhere between
    microwaves (known to be dangerous) and ultraviolet (also known to be
    dangerous).  This wavelength is one which is easily absorbed by our
    eyes.  It is absorbed by some objects, but reflected by others.
    
    These devices are turned on in the morning, and then turned off at
    night.  If you think your building has these devices, here are some
    identifying features:
    
    	o They are usually located overhead.  Some are placed on desks.
    
    	o They either have several long glass tubes, or one or more glass
    	  bulbs.
    
    	o There are probably several in an office.
    
    Obviously, these devices should also be researched for their
    side-effects!
    
    	Rich 
    
    	(who thinks that we all should take this topic, as well as
              my reply with a grain of salt and a ;-))

    re: .11

    Fluorescent lights emit enough energy to cause random erasures in
    UV-erasable EPROMs.

 re .4

>    The series of articles discussed the PAVE-PAWS installation on Cape
>    Cod, which electronically switches its microwave signal around the sky
>    at tremendous speed.  I don't have the articles handy (I'm circulating
>    them), but I recall there was a harmonic at 73 hertz, which is in the
>    ELF range.
 	Usual technical usage reserves "harmonic" for referring to signals
	_above_ the fundamental, at 2x or 3x or Nx (n==Integer) multiples.
	PAVE PAWS is a uwave, so the 73 Hz is not a harmonic, sounds like the
	the scan rate.

    
>    Since the installation has been operating, independent epidemiological
>    studies have been conducted, and they have indeed turned up a slight but
>    distinct rise in cancer rates around the site.
	Would need to know more about the studies.  Ferinstance, I believe
	stress has been shown to increase cancer incidence.  In this case, the
	stress of being told they were "...experimental animals...".


>    The mechanism by which ELF radiation causes harm is not well
>    understood, but it is not related simply to the power being absorbed by
>    living tissues.  It is related to the frequency, and, unfortunately, 60
>    hertz is a bad frequency.
	I would like definition of why or how 60Hz was determined to bad...

.....

re .5
>This is one of the basic problems that many people refuse to acknowledge. 
	Perhaps be cause it doesn't exist.  _note_ I said _PERHAPS_.
	more study should be done.  But, in my opinion, there are other,
	bigger worries that are much better demonstrated.

>...

>Hopefully LCD screens will reduce the CRT problem, but other sources of
>EMF continue to pollute our living "space".
	See previous comment on general increase in human lifespan and health
	as electricity has been more widely used.

>No one in business wants to acknowledge the problem, but then it's not visible
>is it.  I hope some sort of cheap Geiger counter becomes available to measure
>this invisible danger.
	Sigh.  You're welcome to borrow mine.  Seriously.  None of the
	discussion to this point has concerned the sort of "radiation" that
	a geiger counter measures.  (Aside: "Radiation" is a word with way
	to many meanings, even in technical discussion.  In technical discussion
	its exact meaning follows from the context.  Will post more on this
	later.)
	As to detectors for "ELF" or any other sort of "radiation" they can be
	had.  for ELF, they are called "radio receivers" although not the usual
	ones.

>erik

re .6
>    I can't believe this stuff won't go away.  60-hertz radiation has
>    been with us since the turn of the century.  It's probably close
>    to impossible to study it's effects on humans because there are
>    no non-radiated control groups around.
	Australian Aborigines, most of the population of Africa, South America,
	isolated Australian non-aboriginals, probably some of the
	USSR population, India (?).  The trick IS to find one where the
	other medical aspects are comparable to high "elf dose" population,
	such as US, Western Europe, etc...

>  It's also true that those areas where electricity is in heavy general use
>  are those wher the life-expectancy of the population is highest.  Yes, this
>   is from other factors, but you probably can't get one without the other.

...

>    Don

    re: .12

>    Fluorescent lights emit enough energy to cause random erasures in
>    UV-erasable EPROMs.
	If exposed for years...

thanks
dave pierson

    RE: .5  Geiger Counter
    
    Back in the mid Seventies I had a citizen band radio which I used
    when on camping trips with friends.  In Baja California we could
    turn the squelch to zero and there was no background noise.  In
    San Diego we had to turn the squelch up to about 4 to cut that noise
    out.  When I got out of the camping routine in the early eighties
    it was impossible to use the CB in the San Diego area at all but
    in remote areas there was still little to no background noise.
    
    Irv Waldo

    re: .13

>>    Fluorescent lights emit enough energy to cause random erasures in
>>    UV-erasable EPROMs.
>	If exposed for years...

    In one lab I worked in the average time between reprogramming and user
    observed intermittent failure was 6-8 weeks.

    I don't know about the flourescent lights (actually I do, but I'm
    not telling) but I must admit to several serious personal memory
    erasures resulting from having been smitten by radiant smiles. 
    
    The error message I get is:
       "Good Lord she's beautiful!
        Now, where was I going??"
    
    

"radiation" is a word used in many contexts, and having different meanings.
If these meanings are mixed, confusion results.  I am posting this to provide
background for discussion, not to "prove" there is (or is not) risk.

Perhaps the meaning we can call "original" could be "going out from", for
instance "The roads radiated from the city.".  This usage has become uncommon.

In technical jargon, it can be either used in this same sense:
	"Radiation took place from the antenna".  (or: fireplace, sun, reactor).

By extension, it has taken on another sense, as "some thing (or energy)
radiated":
	microwave radiation, solar radiation, atomic radiation.

To add to the confusion "atomic radiation" lumps together two VERY different
things:  high frequency electromagnetic radiation: gamma rays, x rays
particles: electrons (Beta Rays), helium nuclei (alpha rays), neutrons. 
Shielding methods, hazards or measuring techniques associated with one form of
"radiation" may be totally meaningless when associated with other forms of
"radiation".

For instance, the Geiger counter is capable of detecting Betas, Alphas, and
to some extent Gammas.  It is incapable of detecting lower frequency
radiation (radio, heat, light, uv).

Setting aside the "particles" (electrons, protons, alpha's, neutrons), let
me offer a brief tour of the "electromagnetic" spectrum.  None of the joins
between named regions is "hard and fast", they merge into each other.
Frequencies measured in Hertz, abbreviated Hz, one cycle per second.

Electromagnetic radiation is so called because it consists of an electric
and a magnetic field traveling together.  Note that where wires carry
energy, the amount radiated depends on the arrangement of the wires.
"electric power" lines are designed not to radiate, as the objective is to get
the energy to the other end.

	Kilo=K=thousand
	Mega=M=Million (ferinstance, 1 Million Hertz, One Million cycles
			per second, is in the middle of "AM" radio.)
	Giga=G=Billion (ferinstance, police speed radar is on 10.xxx Ghz
			Billion cycles per second)
	Above that, the abbreviations aren't so well known, so I will spell
	them out.

	ELF	Below 3KHz.  Commercial power distribution at the low end.
		Radiation (energy leaving the wires) is inefficient.
		Some portions used for communication due to seawater
		penetration.  "Specialized radio" possible.

	VLF/LF	3KHz-300KHz.  start of "radio".  Marine and navigation,
		mostly.

	MF/HF	300KHz-30 MHz	"AM Broadcast Radio", plus "short wave"

	VHF	30-300 MHz	"Police Band", military Communication,
		start of television broadcast, "FM Broadcast".

	UHF, EHF, SHF
		300Mhz-300GHz	(Somewhere in here, "microwaves" start.
		They are just higher frequency radio waves".)  "UHF" Television
		(Chs 14-83), radar, satellite communication, navigation
		radio astronomy.  Microwave ovens, 2450 MHz

	pause for breath:
	Now passing 300,000,000,000 vibrations PER SECOND... At this region,
	we merge into the "infrared", some times called "heat radiation".

	At roughly 20,000,000,000,000 per second is the "red" end of "visible
	light, where the average human eye starts "seeing".

	At 200,000,000,000,000 per second we leave visible violet for "ultra
	violet", which is invisible.  (The light "seen" from a UV light is strays,
	inefficiencies.)  Short UV causes skin cancer, maybe long UV also.

	At 20,000,000,000,000,000 per second.  "short wave" UV fades into
	"x rays".  Medical X Rays, known hazard from excess dose.  Debate over
	effects of low dose.

	At 2,000,000,000,000,000,000 per second "gamma rays" start.  High
	energy nuclear stuff.  Nothing pleasant up here.

All of which is background info.  Doesn't "prove" ELF or anything else safe or
harmless.  It does, demonstrate that "electromagnetic radiation", as a phrase,
covers a large range of "material".  It needs more words before any
comparisons or conclusions can be drawn.

What's not obvious (I'll just state it and leave it) is that as the "frequency"
goes up, the minimum amount of energy (ability to cause "effects" or "Damage")
that is present in the EM field goes up.  Thus, "radio" is "inherently" safer
than "UV".

thanks
dave pierson

    re: Roms:
    	Must vary from manufacturer to manufacturer, or device to device.
    	Ones we were using were specced at years.
    
    
    re: CB noise level.  Just listening to all the "other" CB's, mostly too
    	far away to hear plainly.  Step a little "outside" the band and the
    	noise level will fall right down.
    
    thanks
    dave pierson

re: .13:
>	I would like definition of why or how 60Hz was determined to bad...

According to one of the scientists quoted in the article -- soon to be
a book -- it synchronizes with intracellular ion (calcium) transport.
Read the article for some more detail.

>>I hope some sort of cheap Geiger counter becomes available to measure
>>this invisible danger.
>	Sigh.  You're welcome to borrow mine.  Seriously.  None of the
>	discussion to this point has concerned the sort of "radiation" that
>	a geiger counter measures.

In context "Geiger counter" sounds like a shorthand for "thing that measures
this sort of radiation."

>	As to detectors for "ELF" or any other sort of "radiation" they can be
>	had.  for ELF, they are called "radio receivers" although not the usual
>	ones.

For sure, but what the articles imply is that the "radio receiver" must be
able to detect and measure the ELF (15-70 Hz) pulses and, in the case of
Pave Paws, must measure instantaneous energy, not the significantly lower
average energy.

>>    I can't believe this stuff won't go away.  60-hertz radiation has
>>    been with us since the turn of the century.  It's probably close
>>    to impossible to study it's effects on humans because there are
>>    no non-radiated control groups around.
>	Australian Aborigines, most of the population of Africa, South America,
>	isolated Australian non-aboriginals, probably some of the
>	USSR population, India (?).  The trick IS to find one where the
>	other medical aspects are comparable to high "elf dose" population,
>	such as US, Western Europe, etc...

One of the more interesting studies (in the second article) noted differences
in fetal abnormalities/miscarriages in families that used electric blankets.
There were seasonal variations that coorelated in unexpected ways with
detected miscarriages.

Again, read the articles for more information.

Martin.

    Re: Electric Blankets & Miscarriages.
    
    I wonder what controls were used.  Specifically, I wonder if there
    was a control group sleeping under some other (hot water) form of
    external heating device which might well raise fetal temperatures
    beyond the appropriate.  Even the opposite could happen, couldn't
    it?  The blanket, in keeping the outside of the mum toasty, could
    trigger her cooling system (presumably on the bottom of her, away
    from the blanket) which would chill the womb.
    
    A more valuable study would be one which quantifies the negative
    effects of the stress induced by publication of such paranoid reports.
    
    I guess all this worrying and fussing means my idea of using a
    micro-wave oven in the roof to heat the people rather than the house
    in winter is a no go, right?  And to think the plumbing problems
    had been solved by the widespread use of plastic piping.  Oh, well,
    it's back to the solid-state nuclear battery.
    
    
    Don
    

I have always believed that the problems caused by the stress of reading this
type of "information" on potential hazzards (such as electric blankets) are more
harmful than the hazzard we are being warned about.  

    Re: [.21]:  Have you read the studies?  Have you even read the
    articles?  If not, the only reason you would have to cast aspersions,
    such as labeling the information "'information'," would be that you
    don't believe it.
    
    What we don't know sometimes CAN hurt us.  Read the articles.  Make an
    informed judgement.

start panicing!!!   Otherwise we'll radiate all kinds of deadly rays and 
electromagnetic poison with all these educated people using the death 
dealing devices to convince us we're on our way to self destruction!!

Please - panic!!!   All our lives are in danger!!!

Bruce

Next step - get Mass. to outlaw the Sun!  That damned thing irradiates us 
with all sorts of deadly rays.  Just because it's a zillion times what man 
produces isn't important - I know 'cause I read it at the grocery checkout 
line!!!

RE: 22: Have I read the studies?  I was part of a group that _commissioned_ 
studies while at Raytheon.  We even had outside people come into our facility
with detection equipment to give us an independent evaluation (this included 
the manufactuing line where we were building and testing displays).  The report
indicated that the _only_ area to be concerned about was a minor leak in a seal
on a microwave oven in the vending area.  I have seen this gone through at
three computer companies (not counting Digital) and the results were always
the same - that the radiation from displays was nothing to be concerned about.
I have read enough articles and studies on this subject to satisfy me that I 
should not be concerned about this until some "authority" such as the EPA or the
Surgeon General makes some statement that there _is_ something here to worry
about.  I _am_ convinced that the rise in my blood pressure resulting from 
responding to this note is causing me more harm than the radiation from this
monitor that is sitting in front of me.

    It's ironic that we're all arguing this point by sitting in front of
    VDTs...  I hope this discussion isn't viewed as a rat-hole; I sincerely
    believe that this alleged health hazard is fundamental to all of us who
    work with VDTs and computers.  (It would certainly overshadow the
    hazards of paper cuts, which now is #1 on my list.)  
    So I continue, with your indulgence.
    
    Re: [.24]: Just so:
    
>> 					...  I have seen this gone through at
>> three computer companies (not counting Digital) and the results were always
>> the same-that the radiation from displays was nothing to be concerned about.
    
    As you yourself say, VDTs emit "radiation."  None of it is very
    powerful; we're not talking about hard-boiled eyeballs here.  Much of
    the radiation is in forms that I'm willing to bet your evaluation team
    never even checked for, such as 60-hz magnetic fields.  (Hey, no one
    thought about that one until recently.)  I would claim that the
    evaluations you cite were not complete.  And the logical fallacy is to
    assert that the radiation is nothing to worry about (I paraphrase
    many others, not you) because no studies have shown a problem, *when no
    one ever looked for a problem.*  (This is what got Madame Curie into
    trouble.)  Scientists are now performing the studies, and they are
    finding problems.
    
    The _New Yorker_ articles mention two issues of _Scientific American_
    that capture part of the problem we face.  The September 1986 issue
    carried an article called "The Microwave Problem," written by two
    engineering professors, discussing an Air Force study conducted by one
    during the 70s and 80s.  They said the study showed no health problems
    in rats irradiated by low-power microwaves.  Sure, they conceded, the
    rats had lots of tumors, significantly more than the control rats; but
    the tumors weren't concentrated in any one part of the body.
    
    Ah, but here's the rub!  In the December 1986 issue, an editor of the
    _Microwave News_ who had access to the original study wrote a letter
    refuting the authors!  He pointed out that they had misstated their own
    facts; the rat tumors were mostly concentrated in the endocrine system. 
    He pointed out that they study DID show positive results.  The two
    engineers had taken $4.5 million from the Air Force, done a biological
    study for which they were not qualified, then twisted the results to
    the buyer's liking.  THIS, the letter asserted, was the real "microwave
    problem."
    

    Another bit of anecdotal indication towards a "low hazard" scenario:
    
    Workers in the Electric Power industry (I'm referring to power plant
    and substation personnel, more than linemen) work in and around
    magnetic and electric fields of the ELF type constantly.  I would think
    that their unions would have picked up anomolies.
    
    I do believe that more study should be done.
    
    re:
    "Geiger Counter":
    	I feel strongly that discussion of technical issues (which is
    	what we are discussing here, unfortuantely, ones we don't know
    	the answers to) is a place where as much clarity as possible
    	is needed.  If I can't be sure that someone is speaking
    	figuratively, I will clarify.  Especially as there is much
    	confusion on "radiation".
    
    thanks
    dwp

    re .26:
    
    Well, that assumes that the unions are looking for those particular
    hazards.  Something that causes you to die a few years earlier than
    you normally would, but after retirement, would not be too obvious.
    In the case of the electric power industry, the hazards of EM radiation
    are probably swamped by the other hazards inherent in jobs involving
    climbing, heavy equipment, and high voltage.
    
    /Dave

    The problem that plagues this entire subject is that we are trying to
    assess the incremental hazard caused by long-term exposure to extremely
    low dosages.  Separating these effects out from the background noise is
    extremely difficult.  As .26 suggested any reductions is the statistical
    life-expectancy of a population can just as easily be attributed to
    incorrect evaluation of other hazards.

    The entire topic of VDT-related hazard is clouded by the failure to
    distinguish between differing classes of users.  I would suggest, for
    instance, that the job-related stresses experienced by software
    engineers are vastly different from those that a data entry operator
    has to handle.  We (software types) are not measured on our keystroke
    rates. We don't have supervisors peering over our shoulders.  We can
    get up and walk around, talk to associated whenever we feel like it. 
    Until you do a study that separates out these factors, requests for
    measurements of EM radiation are really irrelevant.

    In this same vein, we hear so much flap about computer terminals, but
    what about the most common VDT -- the television set?  I know many kids
    who spend HOURS each day sitting 2 feet from a 27 inch color monitor. 
    I've seen no suggestion that excessive TV watching represents a health
    hazard (other than mental ;^).  I can't see how a cathode ray tube
    becomes more lethal when connected to a computer.

    We certainly need more studies, but we need the RIGHT studies.

    [.28] raises an excellent point, to which I think the answer is that
    the alleged danger from VDTs is in circuitry that radiates out the
    sides and back; since people sit in FRONT of their TVs, the danger is
    less.  (Either that or the answer is "TVs are just as dangerous as
    VDTs," in which case we're all sunk 8^)

    [.26] also raises a thoughtful question: are electrical workers
    affected more than the general population?  (I praise this question not
    only because it's a good one, but because I can refer to the New Yorker
    articles and answer it 8^) 8^)  Installment 1 of "The Annals of
    Radiation" spends about two pages summarizing seventeen (17) studies of
    workers who deal regularly with strong electric and magnetic fields,
    fifteen of which showed greater-than-normal cancer deaths.  I tire of
    typing them all, but here are some good ones:

    o	Of 438,000 worker deaths in Washington State between 1950 and 1979, 
    	EM field workers in 10 of 11 categories died of leukemia more often 
    	than the others	(categories included aluminum-reduction workers, 
    	electricians, power and telephone linemen, power-station operators, and
    	motion-picture projectionist, who work near step-up transformers)

    o	Electrical workers in England and Wales; of 537 deaths from
    	acute myeloid leukemia studied, electrical workers cropped
    	up much too commonly (especially "telecommunications engineers")

    o	Of white male residents of Maryland who died of brain tumors 
    	between 1969 and 1982, a significant number were electricians,
    	electrical or electronics engineers, and utility servicemen.

    o	Of men who died of brain cancer in East Texas between 1969 and
    	1978, a significant number worked in the communications,
    	utilities, and trucking industries.  The risk for EM field
    	workers was thirteen (13) times that for workers who weren't
    	exposed to EM fields.

    Of particular interest are aluminum-reduction workers, who deal with
    75,000-amp direct-current electric fields.  They die of cancer at six
    times the national average, but not, as the researcher expected, of
    lung cancer, but lymphatic cancer.  This is the researcher who went
    through the half-million death certificates in Washington State,
    looking for a connection between EM fields and cancer-related deaths.
    (After the other major aluminum companies refused to let the researcher
    conduct follow-up studies with their workers, Kaiser Aluminum invited
    him to study theirs.  I think Kaiser is to be credited for not trying
    to avoid the issue.)

    The bottom line is that a good number of studies have been conducted
    into just this question, and they pretty much all turned up a positive
    result.

I wonder if any readers from the Scandanavian countries could share
some insight into the local requirements regarding VDT radiation.  The
Annals article mentioned a series of experiments conducted in that
region, which convinced the government(s) to impose new regulation. 
Facts would be welcome; my recollection is vague.
                                                   
For those who are waiting for the Surgeon General's report, would
a non-US report suffice?

Personnally, I read the articles with great sketicism.  As a layman
trying to read between the lines, the article looked like bad science.
It cited a dozen or so studies that showed a positive correlation 
between ELF exposure and health impact;  and it established that many
of the voices who criticized or dismissed the studies had a vested
interest in  non-regulation of ELF radiation.  It did not include much
of a survey of the studies that showed negative correlation, and I
expect that they vastly outnumber the positive conclusions. It
accepted results despite the fact that they were not consistently
reproducible in other settings.  And a reader shouldn't ignore the
fact that, although the New Yorker is a great magazine, articles are
not generally peer-reviewed by scientists.  Why wasn't the article
published in a peer-reviewed journal?


Nonetheless, the article managed to convince me that:
	- Very large doses of low-frequency electromagnetic radiation
	  cause bad things to happen.  (Different studies yield
	  different bad things such as: birth defects in chickens;
	  reduction in immunological reactions in human cells;
	  epidemiologically-significant increases in the rate
	  of leukemia and other cancers.)  I will encourage my
	  kids to avoid careers in Radar maintenance and telephone
	  line repair.
	- The metrics used for measuring the safety of electro-
	  magnetic radiation (in the US) are based on the very
	  narrow view that the only danger is from the heat that
	  is generated during exposure; and that there are many
	  other factors that should be considered.
	- Despite the numerous studies during the past two decades
	  which demonstrated no danger from VDTs (and other elf 
	  sources), we haven't yet heard the last word.
	- The FCC Regulations on EMI/EMC have already blunted
	  much of the *possible* danger to VDT users.
	- There could be dangers to VDT users, but as of now
	  these dangers are not significant enough nor well-established
	  enough to cause me to abandon my VR260 for an LA36.

    For what it's worth:
    
    There was a TV flap maybe 10-15 years ago concerning radiation.
    
    Power transformers used to contain a coolant with PCBs in it.
    Would low-level leakage in the occasional transformer explain
    the health effects on many of the electrical workers?

re: .30:
> I wonder if any readers from the Scandanavian countries could share
> some insight into the local requirements regarding VDT radiation.  The

There are magnetic field regulations in Sweden, but I don't know whether
they are "government regulations" or part of the purchase specifications.
I have been told that Dec modifies terminals that are sold in Sweden, and
the New Yorker article notes that IBM also modifies their terminals (pc's?).

I have read a survey of VDT magnetic field strengths published in a daily
Stockholm newspaper (equivlant to the New York Times).  As I recall, the
VT100 was pretty low, while the VT220 was much higher.  I don't recall the
exact numbers.  I believe that this was published in June 1986.

> For those who are waiting for the Surgeon General's report, would
> a non-US report suffice?

If you could find one, I'd be happy to translate its conclusions.

> And a reader shouldn't ignore the
> fact that, although the New Yorker is a great magazine, articles are
> not generally peer-reviewed by scientists.  Why wasn't the article
> published in a peer-reviewed journal?

This article is "popular science" from the magazine that published
Rachel Carlson's Silent Spring and John Hersey's Hiroshima.  I would
have liked to see better "science" but the New Yorker is not in the
same league with the Weekly World News.  Brodeur is, however, *not*
an unbiased seeker after truth.

Martin.

    re:
    	The aluminum workers:  The process involves _molten_ aluminum
    	oxide, with (at those temperatures) outgassing of impuritities.
    	(still, a case worth study, They are "DC fields" not ELF, but
    	there will be "some" ripple.
    
    re: PCB's, good question.  What is the principal cancer associated
    	with PCB's?
    
    re: TV sets.  My recollection would have been 20 years ago.  Soft
    	xrays off the face of the picture tube.  Since then tube
    	structure and operating voltages (i think) have been changed.
    
    re: "all the studies are positive".  I would suspect that may be
    	"all the studies reported here are positive".  One study
    	( I think its in the articles, which I haven't read my copies of
    	yet.) was positive by ONE case.  No allowances were made for
    	localaized chemical exposure in that study, so a rerun might have
    	shown "no effect".  My point is that these studies have to be
    	checked, and rechecked.  The numbers indicating "effect" are
    	_real_ close to the numbers indicating "no effect".  Its not
    	at all like smoking, or asbestos, where there was a _real_
    	solid corelation.
    
    re .32:
    	Can you give us some more background on Paul Brodeur?  My
    	article copies don't include anything.
    
    thanks
    dave pierson
    

re: .33:
    	The aluminum workers:  The process involves _molten_ aluminum
    	oxide, with (at those temperatures) outgassing of impuritities.
    	(still, a case worth study, They are "DC fields" not ELF, but
    	there will be "some" ripple.

There will also be magnetic fields, unless my high-school physics textbook
is out of date.  Also, when the electrodes are put into the oxide, the arc
ought to generate a pretty hefty pulse.

One might expect a specific range of cancers caused by "outgassing of
impurities." These were apparently a different variety.

    re: PCB's, good question.  What is the principal cancer associated
    	with PCB's?

Soft tissue, if I remember correctly.
    
    re .32:
    	Can you give us some more background on Paul Brodeur?  My
    	article copies don't include anything.

He's also written on microwave -- I think the book was called "The Zapping
of America."  He is not a scientist.

Martin.

    Re: The Aluminum, telephone and Utility industries...
    
    I would suggest the one thing all three have in common is NOT
    electromagnetic radiation: Aluminum is smelted DC; Utilities use
    60 Hz AC; and Telephones run 48V DC and shield the poop out of
    everything (or at least they used to).  
    
    What they DO have in common is molten metals and their vapours -
    Aluminum people have their lightweight stuff and the rest of them
    have LOTS of LEAD.  They are all exposed to large amounts of copper
    as well.
    
    You can NOT assume that since breathing the air doesn't cause lung
    cancer it doesn't hurt you.  Drinking a lot does not cause cirhossis
    (sp?) of the stomach.
    
    The radiation from household TV's which is presumed bad and therefore
    checked for is X-ray radiation from the high-voltage unit.  The
    worst surprise being the GE "Portacolor" about 20 years ago which
    had no shielding and which you could almost watch right through
    other members of your family.
    
      

        From VNS #1866:

VNS COMPUTER NEWS:                            [Tracy Talcott, VNS Computer Desk]
==================                            [Nashua, NH, USA                 ]

[...]

 VDTs - New study focuses on VDT users. Pregnant women feared to be at risk
        {The Nashua Telegraph, 24-Jul-89, p. 5}
   A new federally funded study on 8,000 women office workers aims to resolve
 persistent questions over whether video display terminals can harm the health
 of people who use them. The two-year, $2 million study is being conducted by
 the Mount Sinai School of Medicine in New York. The Mount Sinai
 epidemiological study is being funded by the National Institute of Child
 Health and Human Development, a unit of the National Institutes of Health. The
 study comes in the wake of a report issued last month by the Congressional
 Office of Technology Assessment, saying more research is needed to explore the
 potential health risks of power frequency electromagnetic fields -
 particularly their effects on the central nervous system and possible role in
 promoting cancer. The OTA report said that while most public concern has
 focused on high-voltage transmission lines, more attention should be paid to
 exposure to fields from other sources such as household and office wiring,
 appliances and other electrical equipment, including VDTs. "It is now clear
 that 60 Hz (cycles per second) and other low frequency electromagnetic fields
 can interact with individual cells and organs to produce biological changes,"
 is said. "The nature of these interactions is subtle and complex. The
 implications of these interactions for public health remain unclear, but there
 are legitimate reasons for concern." Michele Marcus, the Mount Sinai study's
 principal investigator, said it will be conducted in four cities - New York,
 Boston, Cleveland and an as yet undetermined city in California. Both union
 and nonunion workplaces will be included. Dr. Marcus said a major difference
 between the Mount Sinai project and previous epidemiological studies in this
 country is that in addition to gathering health-history data through
 questionnaires, "we are going to be looking at reproductive effects
 prospectively. That is, we're going to be following women forward in time."
 "We'll be identifying their exposure or their use of video display terminals,
 and then seeing whether or not they get pregnant and following the course of
 pregnancy," she said.

    re: .36---Some wag will conclude from the study that watching TV can
    get you pregnant.  I wonder what that will do to TV watching habits.
    Maybe it will just provide a new excuse: ``Really, Daddy, it wasn't
    Jim or Mike or David or Joey; it was the TV!''
        John Sauter, whose daughter is 16 years old 

    re: .36
    
    Please understand that a researcher's product is the research and
    not the answer, and thus the marketing of the product always suggests
    the research needs to be done.
    
    The implication that because things interact and we don't see the
    effects and don't understand the mechanisms are generally followed
    (or preceded) by the veiled threat that everyone is about to die
    if you don't fund my project.
    
    Don
    (42 & counting with 36 years of happy TV viewing)

    Sort of related, and illustrative of the subtleties involved in
    trying to make a correlation, especially with "low level" effects.
    
    	It seems there is a phenomenon known as "the sick building".
    (NO, NOT one with a bad foundation...)  One that makes its
    occupants typically office workers (in the broadest sense)
    sick:  headachy, general low grade irritating type symptoms.
    
    It's apparently a real effect.  It doesn't (in an obvious way) involve
    EM fields (of any frequency), as it is specific to certain buildings,
    NOT to certain job descriptions.  Typical building is a modern, multi
    floor office building, sealed, air conditioned, big enough floors so
    people are away from the windows. Good buildings, IE well designed,
    not classic poor ventilation, etc.
    
    No obvious culprit, though guessing about plastics "outgassing" some
    of themselves is one possibility.  Some obscure EM effect is another
    possibility, though not mentioned.  (source: BBC Science program on the
    SW...).
    
    OK, back to .0.  The above illustrates an apparently recognized_but_not
    _understood affect.  A low level effect.  Assuming the "sick building
    effect" is not an EM
    effect, then, IMHO, an study looking for an EM effect that doesn't
    discount the "sick building effect" is going to come up with
    "misleading" answers.  Some of the "cases" attributed to EM are going
    to be "sick building" cases.
    
    thanks
    dave pierson

    The following excerpts from "Annals of Radiation" were uploaded to the
    Boston Computer Society's Macintosh BBS by an anonymous source.  (It
    was not me 8^)  I haven't checked the passages for accuracy, but they
    sound familiar.  I have reformatted, but not otherwise changed, the
    text.
    
    	*	*	*	*	*	*	*
    
The following excerpts are from The New Yorker magazine's
three-part (June 12, 19, 26,) article entitled "Annals of
Radiation" by Paul Brodeur.  IF YOU VALUE YOUR HEALTH AND WORK
WITH VDT'S YOU WILL WANT TO READ THIS SERIES!  The first part is
about magnetic fields surrounding power transmission lines, the
second part is about radar and ELF fields, and the excerpts to
follow are from the third part entitled "VIDEO DISPLAY TERMINALS."
You can send to the New Yorker for back issues, they're $3
each.  The address is:  25 West 43rd Street, New York, NY 10036.

"The attempt of the utilities industry to play down the hazards
of exposure to electric and magnetic fields from power lines has
been abetted by a reluctance on the part of many people to
recognize the possibility that their health might be threatened by
invisible emanations from something they regard as both pervasive
and indispensable.  Indeed, so dependent are we on the benefits of
electricity, and so accustomed have we become to the vast
spiderweb of the electrical-distribution system surrounding us,
that we have accepted without question the necessity and ubiquity
of its presence.  This, in turn, has made it easy for us to
embrace without reservation virtually all the hundreds of
electrically powered devices that have been introduced into our
homes, our workplaces, and our environment, and make no
distinction among them other than to be aware of the different
tasks they are designed to perform."

"From the outset, the manufacturers of computer terminals have
been disinclined to measure the strength of the magnetic fields
that emanate from their products, or give out information about
these fields.  Indeed, only recently have any of them acknowledged
that VDTs can produce such fields."

"When VDTs are operating, they emit X-rays from their cathode-ray
tubes, but so much of this radiation is absorbed by the glass of
the CRT that it is not considered to pose a health hazard.  The
other radiation given off by VDTs includes ultraviolet, visible
light, infrared, microwave, radiowave, ELF, and static electric
fields.  Most of it consists of pulsed VLF electric and magnetic
fields of between fifteen and twenty kilohertz, and pulsed ELF
electric and magnetic fields of sixty hertz.  The pulsed VLF
radiation is produced by the flyback transformer and the
horizontal-deflection coil.  the sixty-hertz electric and magnetic
fields are generated in two ways:  Sixty-hertz fields originating
in the 120 volt current that powers the VDT are emitted by the
machine's power transformer (since these fields decay rapidly over
distance, they can usually be measured only in the immediate
vicinity of the transformer); and much stronger sixty-hertz
magnetic fields are produced by the CRT's vertical deflection
coil..."

"Between February of 1979 and February of 1981, seven out of
thirteen pregnant women who worked part time at Air Canada's
check-in counter at Dorval Airport, in Montreal, miscarried... In
December of 1980 it was learned that between October of 1979 and
October of 1980 three cases of congenital malformation and seven
cases of first trimester miscarriages had occurred among pregnant
workers at the Marietta, Georgia, regional headquarters of the
Department of Defense's logistics agency...  Delgado and Leal
reported that 100-hertz magnetic fields of twelve milligauss in
intensity had "a powerful effect on chick embryogenesis, delaying
or arresting it at a very early stage and limiting development to
the formation of the three primitive layers, with no sign of
neural tube, brain vessicles, auditory pit, foregut, heart,
vessels, or somites." Indeed nearly eighty per cent of the eggs
they used in their experiment developed abnormally."

"In 1976, there were fewer than a million VDT workstations in the
United States; today there are thirty million.  According to the
Computer and Business Equipment Manufacturers Association, almost
one out of fifteen white-collar workers now uses some type of
computer workstation, and by the end of the century every
white-collar worker will use one.  Thus, if magnetic fields given
off by computer terminals should prove to cause cancer or
otherwise be harmful to health, an immense and continually growing
segment of the nation's population will have been placed at risk."

"Meanwhile, the defacto policy that power lines, electric
blankets, and VDT's be considered innocent until proven guilty
should be rejected out of hand by sensible people everywhere.  To
do otherwise is to accept a situation in which millions of human
beings continue to be test animals in a long-term biological
experiment whose consequences remain unknown."

    Hmm, maybe I *don't* want one of those stereo video headsets with
    the little display just a few inches away from each eye, that they
    were showing at SIGGRAPH last week...
    
    I'll take the DataGlove though, I'm tired of mice.

    re: .40
    
    Now I know why I don't buy the New Yorker - in addition to it's
    snotty attitude, it misleads...
    
    1]  The Cathode Ray Tube (CRT) is so named because it produces INSIDE
    ITSELF a stream of electrons flying through a near-vacuum.  It does
    NOT produce X-rays.  The electrons are the same little guys who
    fly from your fingers after walking across a carpet, and the only
    ones who get out of the glass are the ones you can feel by touching
    the screen.  You'll notice, if you try it, that a colour monitor
    is a little more 'staticy' than a mono-chrome and that your home
    TV is *way* more staticy than any DEC product.  
    
    X-rays CAN be produced by the high-voltage which is required to
    get the electron stream going in the first place arcs, visibly or
    not, to ground.  This is why the coil which is used to generate
    it is in a metal box in most vidoe equipment.  The level of X-rays
    generated by a spark do not penetrate metal.
    
    2]  All those high-tech things like fly-back coils, etc, are also
    transformers.  For some reason the field decay which was mentioned
    with the power transformer as being good was not mentioned with
    the other, specifically- (and therefore more exotically-) named
    coils.  Radiation of this sort decreases proportionally to the square
    of the distance.  This means than at the more than 20" I now sit
    from my Rainbow monitor, the radiation (if any) would be 6,400 times
    less at my face than it is on the outside of the glass.  And, on
    the outside of the glass, it is negligible.
    
    3]  So... people working at Dorval have higher-than-normal miscarriage
    rates.  How about the fact that in the early 50's an 'accident'
    at Canada's Chalk River experimental nuclear power facility which
    is upwind from Montreal spewed clouds of 'hot' steam into the air.
    That milk had to be brought into the area - almost the Wisconsin
    of Canada - because local supplies were tainted.  That whatever
    fell on the topsoil is still there.
    
    This kind of pop-science renders an informed populace nigh impossible.
    
    

    I also think that the article gives power lines a bum rap.  Power in
    the United States is generally transmitted as 3-phase alternating
    current.  That means that power is transmitted on 3 wires.  The
    electricity flowing through each wire is 120 degrees out of phase
    with the other.  At any instant in time the sum of the voltages
    in the three wires is ZERO and the sum of the currents in the
    three wires is ZERO.  Any electric or magnetic field developed
    around the individual wires will mostly cancel out.
    
    Second, it appears that it's the magnetic fields that the
    author is concerned with.  The strength of a magnetic field
    is not proportional to the voltage in the wire; the magnetic
    field is proportional to the CURRENT.  The whole purpose of
    transmitting power at high voltages is to keep the CURRENT
    low.  The reason the current is kept low is to keep the
    diameter of the wires small and light.  The power lines,
    instead of being referred to as "high-voltage lines" could
    just as easily be called "low-current lines."
    
    Any fields that might develop way up in the air diminish
    as the square of the distance.  An electric blanket or
    electric hair dryer produces more of a field than any power line
    could, for the reason that it is so much closer.
    
    The author of the New Yorker article already wrote a sensationalist,
    alarmist book about how microwave ovens are killing us, and now
    he wants to promote another ridiculous book.
    
    

re: .40:
    1]  The Cathode Ray Tube (CRT) is so named because it produces INSIDE
    ITSELF a stream of electrons flying through a near-vacuum.  It does
    NOT produce X-rays.

The X-rays were produced when the electron beam strikes a target (such as
the phosphor).  The article did state (June 26, p. 40) that "so much of
this radiation is absorbed by the glass of the CRT that it is not considered
to pose a health problem."

    2] ...  This means than at the more than 20" I now sit
    from my Rainbow monitor, the [magnetic field] radiation (if any)
    would be 6,400 times
    less at my face than it is on the outside of the glass.  And, on
    the outside of the glass, it is negligible.

The article claims that, while "negligible" by your standards, it is
still capable of biological effects.
    
    3]  ... [sources of radiation affecting miscarriage rates among VDT
	workers at Doral airport].

The article compares miscarriage rates among populations that appear to
differ only in their exposure to electomagnetic fields.  If the miscarriage
rates were due only to exposure to nuclear radiation, there should be no
statistically significant differences in the two groups.  On the other
hand, there could be other environmental "mechanisms" that caused
the birth defects, such as microwave radiation from an airport radar
system (oops, see parts 1 and 2), and there could be totally random
"clusters" that have absolutely no connection to any biological hazard.

    This kind of pop-science renders an informed populace nigh impossible.

The central issue in the article series seems to be that "orthodox science"
(i.e. NIOSH) couldn't measure the electric and magnetic fields and claimed
that "the VDT does not present a radiation hazard ..." and that there was
no reason to go looking for any hazard. (June 26, p 41-42).

Refusing to examine the evidence (even if you don't believe the evidence)
also "renders an informed populace nigh impossible."

Martin.

    

re: .43:
         <<< Note 859.43 by LABC::FRIEDMAN "Don't be happy; worry." >>>

    I also think that the article gives power lines a bum rap....
    Any electric or magnetic field developed
    around the individual wires will mostly cancel out.
    
The article clearly states that the field is unbalanced.  It also
suggests that effects may be due to local secondary transformers
(pole mounted), and that effects are lessened in districts with
underground power distribution.

    The whole purpose of
    transmitting power at high voltages is to keep the CURRENT
    low.  ... [magnetic field strength is dependent on the current.]

In part 1, "the average strength of the alternating-current magnetic fields
measured at the entrance doors of the dewllings near the 200-kilovolt wires
was 2.2 milligauss.  When Tomenius analyzed his data, he found that twice as
many of the homes of children who had developed cancer were near 200-kilovolt
lines as were the homes of control children.  Similarly, the incidence of
cancer in children who lived in forty-eight homes where magnetic fields of
three milligauss or more were measured was twice as high as that in control
children."  (June 12, p. 82).  Research was published in Bioelectromagnetics,
1986.
    
    Any fields that might develop way up in the air diminish
    as the square of the distance.  An electric blanket or
    electric hair dryer produces more of a field than any power line
    could, for the reason that it is so much closer.

People are not cronically exposed to hair driers.  The article does
discuss differences in miscarriage rates that correspond to electric
blanket (and waterbed) usage.

Martin.

    

RE: .43

In a word: bull.

    What does  "The  sum  of  the  voltages  in the three wires" mean?
    Voltage  is  a potential difference, so it is only meaningful when
    there  is  a reference (often "ground"). Similarly saying that the
    sum  of  the  currents  is zero doesn't mean anything. That's true
    whenever  you  have  all  the current carrying elements. Two wires
    carrying  AC can have a noticeable effect on electronic equipment,
    so quite possibly they could have an effect on people.

    While power lines are high voltage to keep currents lower, I still
    wouldn't  call them low current. They carry an awful lot of power,
    so  even  going to a few hundred kilovolts doesn't get the current
    down to what is normally called low.

    I don't  know  whether  the  dangers  mentioned in the article are
    real,  but  responses  like .43 convince me that there's plenty of
    nonsense being spread in the "don't worry, be happy" school.

--David

    "The most amusing aspect of all this is that due to the fallout we have
    picked up over the years (strontium, iodine) we are likely to radiate
    more at the CRT than the CRT radiates at us.  In the past the CRT
    radiation issue has been used as a labor bargaining point in order
    to get more work breaks and shorter work periods.  As the radiation
    picture has been clarified in one band at a time, first X-rays, then
    RF, followed by light and ELF as being safe, it has been the center
    of attention for an extended period of time, and still is useful for
    those wishing to become alarmist."
    
    --From TERMINALS Notes Conference 1392.2

re: .47:
    In the past the CRT
    radiation issue has been used as a labor bargaining point in order
    to get more work breaks and shorter work periods.  

The labor bargaining issues (at least in Sweden) centered around eye-strain
and muscle strain (repetitive motion syndrome); not around "radiation."

   As the radiation
    picture has been clarified in one band at a time, first X-rays, then
    RF, followed by light and ELF as being safe

Where has ELF been "clarified as being safe?"  References please?

Martin.

    RE: .46
    
    sin X + sin (X + 120�) + sin (X + 240�) = 0
    
    Case closed.

    sin X + sin (X + 120�) + sin (X + 240�) = 0

Presuming, of course, that the fields radiate from the same point
with no other influences on the fields.

There's a difference between science and engineering, you know.

Martin.

    From _Electricity: Principles and Application_, 2nd edition, by Fowler,
    published by McGraw Hill:
    
    "In three-phase ac, each phase is a sine wave.  Each phase is displaced
    from the other two phases by 120 electrical degrees. ...  Pich any
    instant of time you desire to compare the three phases.  You will
    find that the sum of two of the phases is always equal in magnitude
    to the remaining phase and opposite it in sign."
    

    There is supposed to have been an article in a recent issue of
    _Time_ Magazine that criticized the _New Yorker_ series.  I
    am in the process of finding out which issue that was.  Maybe
    someone who subscribes can type in some excerpts.

RE: .51

>    ...Pich any
>    instant of time you desire to compare the three phases.  You will
>    find that the sum of two of the phases is always equal in magnitude
>    to the remaining phase and opposite it in sign."

    This statement  is  true for the two wires carrying DC. It is also
    uninteresting.  The fact that there is no net flow of electrons is
    also  unimportant.  The  net  flow  of  electrons  (in  a complete
    circuit)  is  always  zero,  except  for capacitors. A DC circuit,
    where  all  the  electrons  flow  in a circle (no net flow) causes
    magnetic fields.

RE: .49

    Since there  is  no  net current, I assume you would be willing to
    have  each  of  the three conductors attached to one of your limbs
    (with  the  fourth limb attached to ground.) Personlly, I wouldn't
    try it.

    The other  interesting  point is if there is no current, why waste
    aluminum by having wires?

    The wires  are spaced fairly widely, which is what makes the field
    away  from  them  non-zero. The reason they are spaced is that the
    potential  between  the  wires  would  cause sparking if they were
    close  together. That implies that there is some potential energy,
    which might or might not be harmful to people.

--David

        No one said that there is no current.  Although the three
        voltages (currents) cancel each other out, each individual phase voltage
        is readily available.  The full sinusoidal voltage produced
        by phase 1 is available between lines 1 and 3.  Phase 2 is
        available between lines 1 and 2, and phase 3 exists between
        lines 2 and 3.
    
    Here is the point:
    
        The magnetic flux is perpendicular to the direction of the current. 
        The direction of the flux around a conductor can be determined
        by the "left-hand rule."  Grasp the conductor
        with your left hand so that your thumb points in the direction of
        current.  Your fingers then indicate the direction of the flux.
    
        If you add vectorially the directions and magnitudes of the
        fields produced you will see that they cancel each other
        out.
    
        This canceling out assumes, as previous replies have pointed
        out, that the conductors are balanced and close to one another.
        
        
        To the extent that practical power distribution systems deviate
        from the theoretical ideal, magnetic fields may occur.
    
        
    
        

    Re .43
    
    You don't need mathematics to show that a high voltage 3-phase power
    line dissipates energy into the surround air. Two simple obersvations
    suffice:
    
    (i) On a wet day, listen. You will hear a crackling/buzzing sound as
    current flows into the wet air, on its way to the ground. An electric
    field must exist for this to occur.
    
    (ii) On a dark night, hold a flourescent tube in the air, under the
    line. If the line voltage is high enough, the tube will glow. Again,
    there has to be an electric field present for this to occur.
    
    Both of these phenomena represent a leakage of a significant amount of
    energy into the surrounding air (power companies budget for it) and such
    leak must have *some* effect on the surroundings. The energy leak is
    readily detected by human senses of sight, hearing, maybe smell.
    
    Richard.

Excuse me but can someone tell me what button to push?

I was looking for DIGITAL.NOTE but somehow ended up here
in PHYSICS.NOTE.

Is it me, or is my keyboard broken?

---------------

This problem is reproducible because a previous keystroke landed
me in RUMOUR.NOTE.

QAR time?

- greg

Forgot:  NEXT/UNSEEN seems to help, but the contacts are becoming
corroded due to the contamination scavenging that accompanies even
low-current, low-voltage electromechanics.

- g

I wasn't belittling the participants --- I was belittling the discussion.

I don't think a discussion of whether or not the currents and voltages
in a three-phase power system sum to zero, albeit interesting, is either
germane to the topic, nor really a discussion of the "Digital way of
working".

The issue of whether VDTs are dangerous is fine, though apparently
unresolvable at this juncture.  But there is no harm in discussing it.

- greg

ps: BTW --- I definately _don't_ side with the crowd that thinks "hit
    next/unseen" is the answer to every critism of notes.  It's about
    as intelligent as, "[your country] --- love it or leave it".

If you feel an urge to get technical on this topic then I can provide
some pointers:

        CSOA1::ELECTRO_HOBBY conference  (pres KP7 to select)

        Note 1.x        Conference Introduction (read this first!)
        Note 10.x       Cross-country high voltage lines
        Note 672.x      Powerline fields/human harm?

Lee Roth
Electro_Hobby moderator

re: .56:
>                     -< Desparately seeking DIGITAL.note >-

>Excuse me but can someone tell me what button to push?

Well, Greg, you just pushed one of mine: this topic was started to alert
readers to an article series that may affect the way we do business.
If the article is correct, there is a possibility that our products
may (I emphasise "may") be associated with potential injury to our customers
and employees.  That, to put it mildly, is relevant to this conference.

Several people have attacked the claims of the article using what
I -- and others -- feel to be specious pseudo-scientific arguments.  (They,
of course, feel that the articles' tenents are also pseudo-scientific.)
Others have discussed those arguments.

If you believe that the potential dangers of electomagnetic radiation are
not relevant to your work at Digital, you are quite welcome to skip over
the article: if your terminal key breaks from overuse, you should discuss
this in the Terminals notesfile.

I would prefer that you didn't try to cut off discussion here by belittling
the participants.

Martin.

Ps: this is a resubmission of .58 which was deleted by one of the moderators
because the wording of one sentence might be taken by a lawyer to suggest
that Digital was aware of potential harm caused by its products.  In my
reply to the moderator, I pointed out that Digital has been following
this issue for several years and re-manufactures one of its terminals
to satisfy lower levels of electromagnetic field mandated by the purchase
specifications in some countries.  I also pointed out that any lawyer who
could claim that my original wording proved "Corporate Intent" would have
no trouble adding the phrase "Destruction of Documents" (see note 1).

I also corrected a factual error in my original posting: while I have been
a fairly verbose contributor to this note, it was started by Steve Jong.

Here are some references to the medical literature that was originally
posted in CSOA1::ELECTRO_HOBBY.NOTE and is reposted here by permission.

Martin.

                 -< Electro_Hobby. Digital Internal Use Only >-
================================================================================
Note 672.14          Electric fields/power lines/human harm?            14 of 42
KAOM25::TROTTIER                                     71 lines  21-JUL-1989 08:48
                      -< Some facts from the scientists >-
--------------------------------------------------------------------------------
    Just though I would throw in a few facts into the conference
    
    
    In 1979, Dr S. Milham Jr. while updating an occupational mortality
    study, noticed a one and a half to three fold increase in acute
    and myeloid leukemia in persons working in electrical or magnetic
    fields. (New England Journal of Medicine, 1982, Vol 307(4))
    
    In 1982, Wright,Peters and Mack, University of Southern California
    School of Medicine, tested Milhams hypothesis and found similar
    results recorded in the Los Angeles County Cancer Registry. Not
    only did they note the proportional increase in leukemia in electrical
    workers in general but they also identified tlelphone and power
    linesmen as being at greater risk. (Lancet, Nov 20, 1982)
    
    In 1979, Wertheimer and Leeper report a 2-3 fold increase in cancer
    deaths of children living near high current power linesd in Denver,
    Colorado. They could not determine the reason for the increase but
    offered some possibilities to consider:
    
    	o A third factor may be interacting with the cancer and power
    	  line association to produce the increase seen.
    
    	o The magnetic fields may somehow directly cause cancer (there
    	  is no independent evidence to support this conjecture)
    
    	o The powerlines may create some indirect effect on some ambient
    	  environmental carcinogen.
    
    	o AC magnetic fields may indirectly affect cancer development
    	  through some physiological process such as alteration of cellular
    	  growth rate, or of the immune system reaction.
    
    (American Journal of Epidemiology, Vol 109, #3, 1979, 273-84)
    
    
    Dr. Phillips, of the Batelle Pacific Northwest Laboratories,
    Washington, reported on a 4 year experimental study in which swine
    were bred in a 60Hz-30Kv/m fields to emulate those fields which
    are directly beneath high voltage transmission lines and which would
    therefore, be experienced by humans. After 18 months of exposure
    the offspring were found to have an abnormality rate twice that
    of the controls (American Institute of Biological Science, commissioned
    papers for Extremely Low Frequency(ELF)  research project, May 1985)
    
    Robert Becker, M.D. Upstate Medical Centre, Syracuse, N.Y., exposed
    mice to 60Hz electromagnetic fields of strenghts approximating those
    found near high voltage transmission lines for 30 days. At the end
    of this time a pattern evolved in the findings that suggested the
    the stress adaption syndrome. Changes in hormones, body weight,
    and blood chemistries were noted. Three generations of mice were
    reared in such a field and by the third generation a 50% infant
    mortality rate was noted as compared to the normal rate of 15%.
    These mice were under unabating stress from electromagnetic field
    and consequently their defences were exhauted. (Report, 1180, Naval
    Aerospace Research LAboratories, Fort Laurderdale, 1973)
    
    
    The use of electric blankets have been linked to miscarriage and
    premature births. The manufactures have responded by re-designing
    the blankets in such a way, that the magnetic field originaly produced
    by the wires now cancel themselves out.
    
    Yes there are many things more deadly or toxic that effect us today
    or in the near future that we must react to and we must also think
    of the future generations to come. I do not wish to expose my children
    to unnessary hazards that do not produce immediate reaction. My
    daughter will not be going to the BRIDLEWOOD ELEMENTARY SCHOOL that
    is located underneat a twin 500KV hydro line while the scientist,
    politicians and industrie argue about the effects of long term exposure
    to ELF radiation. 

    I have read the Office of Technology Assessment Background Report
    on the subject.  There are many studies that show absolutely no
    statistical correlations.  And the studies that do claim a
    statistical correlation generally have been very poorly designed
    or implemented.  Mr. Brodeur's articles were very misleading
    because he picked and cited only those studies that support
    his thesis, without mentioning the studies which had contradictory
    findings or scientists' critical reviews of the studies.

    
    The April, 1990 Scientific American has a review of of Brodeur's
    "Currents of Death".  Haven't read either the review or the book yet
    (except insofar as the book was extracted in The New Yorker).
    
    thanks
    
    dwp