The RF energy could conceivably have an effect on cell membranes and the
potentials that develop across cell membranes. Perhaps some cells are more
sensitive to such changes in membrane potentials and lead to higher incidences
of certain diseases which in this case is leukemia.

As for not noticing the correlation for over 80 years that isn't so unusual. It
really is contingent on many factors including the increase in the number of
stations over the years, the increase in power over the years, the proximity of
the population to RF over the years (ie. the shift from a rural to an urban
population), the extent of the exposure, lifestyle and dietary changes and so on
and so on. It such a case it may take quite awhile to isolate a potential
causative agent and even then it wouldn't be overwhelmingly conclusive proof.
Too many variables to take into account.

Regards

John Barnard

Frank Dresser wrote:

"lsmyer" wrote in message
...
This is a link to an article investigating leukemia rates in areas near AM
transmitters.

http://www.wired.com/news/medtech/0,1286,64579,00.html

I don't doubt that high levels of RF can be dangerous. The first two chief
engineers I worked with both died of cancer in their 50s.

Maybe they got cancer from some other cause (both smoked), but I still
feel
like I'm inside a microwave oven anytime I'm around an AM transmitter
site.




Wouldn't FM broadcast antennas be an even greater concern? The height of
most adults would make them resonant somewhere near, or in, the FM broadcast
band. I'd expect energy transfer to be more effiecnt from the FM broadcast
antenna to the human body than it is in the AM broadcast band.

Anyway, there's been over 80 years of kW+ levels of AM broadcasting, and it
seems strange this leukemia concern has gone unnoticed until now.

Frank Dresser

"Doug Smith W9WI" wrote in message
...
Frank Dresser wrote:
Wouldn't FM broadcast antennas be an even greater concern? The height of
most adults would make them resonant somewhere near, or in, the FM broadcast
band. I'd expect energy transfer to be more effiecnt from the FM broadcast
antenna to the human body than it is in the AM broadcast band.

I'd sure think so.

On the other hand, the FM signal is radiated from an antenna atop the
tower. Stand at the base of a 300' FM tower, and you're 300' from the
thing that radiates.

At an AM station, the entire tower radiates.

One of the issues with most FM arrays with gain is that, for many, the spacing which
results in the array having gain also results in a fairly pronounced hot-spot
directly above the antenna, where few people would be expected to be, as well as
directly below, where technical personnel might spend a substantial amount of time.
Personally, I think that the AM radiation hazards are overstated in this study, and
that the issue comes more from environmental circumstances by virtue of the fact that
many AM transmitter installations share the same area as other industrial concerns.
--
-----------------------------------------------------------------------------
If there's nothing that offends you in your community, then you know you're not
living in a free society.
Kim Campbell - ex-Canadian Prime Minister - 2004
-----------------------------------------------------------------------------
For direct replies, take out the contents between the hyphens. -Really!-

"Doug Smith W9WI" wrote
On the other hand, the FM signal is radiated from an antenna atop the
tower. Stand at the base of a 300' FM tower, and you're 300' from the
thing that radiates.

At an AM station, the entire tower radiates.
___________

Also - most FM broadcast transmit antennas are arrays of several elements in
a vertical stack to concentrate radiation in the horizontal plane. As a
result the radiation directed around the tower base is much lower than the
station's licensed power.

RF

Visit http://rfry.org for FM broadcast RF system papers.

"Mike Terry" wrote in message
...

"Frank Dresser" wrote in message
...

Anyway, there's been over 80 years of kW+ levels of AM broadcasting, and
it
seems strange this leukemia concern has gone unnoticed until now.

Hi Frank,

Good point but compare to asbestos causing cancer where it can take 60
years
to appear.

Yes, but researchers can also sift through 80 years of public health
records. The people who have, or had, leukemia are known. It shouldn't be
hard to find out who lived near a radio transmitter and for how long. It
might be interesting to ask veterinarians about animal leukemia, since many
transmitters are located in rural areas.

But, since this story is being treated as news, I don't think there are even
any "rural legends" about a connection between leukemia and AM radio
transmitters.

Let's not forget that perfectly random chance is going to usually give us
lumpy results. A perfectly smooth map of leukemia cases would be something
like flipping a quarter ten times and getting exactly a h-t-h-t-h-t-h-t-h-t
result. It could happen, but any lumpy combination is just as likely, and
there are more lumpy combinations to go around.

Random chance alone might give us some leukemia hot spots. Some of those
hot spots might be near AM transmitters. It'll be interesting to see if
other leukemia hot spots are around AM radio transmitters, or if is just one
of those weird number things.


I also often wonder what PCs are doing to us all staring at them all day,
we may be in for a big health shock in the years to come!


Brother Stair used to say that the Internet was Satan's entryway into the
home. He seems to have softened his opposition lately. His website has a
page accepting donations using credit cards and paypal.



Also mobiles may ruin the brain. The consequences could be disastrous.

Mobiles as cellphones? Yes, there's no need to do studies to observe the
brain damage caused by those evil things. Just observe the cellphone addled
drivers as they careen from one close call to the next. The damage is
self-evident. Well, I don't need no stinkin' cellphone to damage my brain.

I'll stick with shortwave radio.


Happy thoughts!!

Cheers

Mike



Frank Dresser

"R J Carpenter" wrote in message
...

"David Eduardo" wrote in message
...

The thoroughly undocumented cases (no studies of groundwater
contamination,
etc.) was based on the effects of stations with twice the power allowed
in
the US on AMs.

Low levels of AM as experienced in the US would be very different.

While I think this whole thing is just another pseudo-science scare.... It
is NOT true that US stations have much lower field strength on AM. AFAIK,
very few foreign stations are directional at any power. Some US 50 kW
stations have pretty potent ERP in their beam. Not a megawatt, but quite
a
bit nevertheless.

the field strength of AM radio stations is measured in volts (microvolts)
not watts.

the field strength is inversely proportional to the square of the distance.

any study that relates any form of radiation, electromagnetic or otherwise
that does not refer to quantities measurements AND duration of exposure to
some other effect such as Leukemia is worthless.


I'm a lot more worried about teens and others I see wandering around with
a
cell-phone permanently attached less than an inch from their brain.

"R J Carpenter" wrote in message
...

I'm a lot more worried about teens and others I see wandering around with
a
cell-phone permanently attached less than an inch from their brain.


And their retinas as well..... 900 mhz --- I can recall around 20 years
ago (don't get on my case as to whether it was 16 or 22 or 18 years ago) but
the FCC advised the amateur radio community that if you don't do something
to increase your numbers, we're gonna have to start taking your VHF, UHF,
microwave allocations away. This spectrum is too valuable for you to hold
when your numbers are declining and you're not using them anyway.

They (FCC) discussed a codeless "communicator" license. The ARRL countered
with a "Novice Enhancement" program, which satisfied the Morse Code fetish
requirement, and, as it turned out, did not bring the 50,000 new hams
per year into the service as they claimed it would. But anyway, IIRC,
somebody's idea was to allow novices voice privileges on 902 Mhz, and it
was not considered seriously , and one of the reasons cited was safety.

"Richard Fry" wrote in message
...
___________

Also - most FM broadcast transmit antennas are arrays of several elements
in
a vertical stack to concentrate radiation in the horizontal plane. As a
result the radiation directed around the tower base is much lower than the
station's licensed power.

RF


Right, but often times there are a large number of people living in high
rise buildings near the FM antenna. It's conceivable there are more people
living in a high power FM radiation area than a high power AM radiation
area.

Frank Dresser

"Bob Haberkost" wrote
One of the issues with most FM arrays with gain is that, for many, the
spacing which
results in the array having gain also results in a fairly pronounced
hot-spot
directly above the antenna, where few people would be expected to be, as
well as
directly below...
_________________

This is true only when each element in the array has high relative field at
+/-90 degree elevation, and the elements are vertically spaced about one
wavelength apart. Shorter vertical spacings reduce such radiation from
these arrays. Using 1/2 wave spacing reduces it to a theoretical zero at
+/-90 degrees elevation (the zenith and nadir).

BUT, the great majority of FM broadcast transmit elements used today have
elevation patterns with very low relative field at +/90 degrees. An array
of such elements also has low relative field at +/-90 degrees -- even with
elements spaced at one wavelength intervals. IOW, no hot-spots above and
below the array.

Patterns of four element types in common use today, and an elevation pattern
for a 6-element, 1-wave-spaced array of one type are included in the PDF
slide show listed as Paper 10 at http://rfry.org.

RF

"Frank Dresser" wrote
... often times there are a large number of people
living in high rise buildings near the FM antenna. It's
conceivable there are more people living in a high power
FM radiation area than a high power AM radiation.
________________

Could happen in the odd case, but not usually. FM broadcast transmit
antennas located on building tops normally have radiation center heights
that easily clear the tops of nearby buildings. If they didn't, the
station's signal would be affected by shadowing (blockage) beyond the nearby
buildings, and have widespread multipath problems from reflections off the
building sides. Competitive issues make this situation unlikely.

RF

The answer to your questions are right here in the FCC's OET56


http://www.fcc.gov/Bureaus/Engineeri...56/oet56e4.pdf



"lsmyer" wrote in message
...
This is a link to an article investigating leukemia rates in areas near AM
transmitters.

http://www.wired.com/news/medtech/0,1286,64579,00.html

I don't doubt that high levels of RF can be dangerous. The first two chief
engineers I worked with both died of cancer in their 50s.

Maybe they got cancer from some other cause (both smoked), but I still
feel
like I'm inside a microwave oven anytime I'm around an AM transmitter
site.