effects of electromagnetic radiation
Updated July 9,
to go to our page on microwave heating
here to go to our page on cell phones
Doc Bruce Banner,
Belted by gamma rays,
Turned into the Hulk.
Ain't he unglamo-rays!
We don't take a lot of time to
monitor statistics on this web site. But here's an interesting one.
Some time around 2008, for a week this was the most-viewed page
on Microwaves101, by far. Noticing this we zoomed in on where the
clicks were coming from. Turns out the Islamic Republic of Iran
was very interested in biological effects of microwaves. Wonder
what they had in mind?
For September 2010, we
are posting a counter to our original thoughts on the subject. There's
new evidence that non-ionizing radiation may be harmful (or at least
affect people), that we should all pay attention to. Here's an email
from CS, and we appreciate his point of view!
One comment/question on
your section regarding the "biological effects of electromagnetic
You are correct in expressing some exasperation and humor at
the general public's concern about non-ionizing radiation (for
example, from cell-phones) with regard to the carcinogenic potential
of such exposure. All of the available science says we're 'good
to go' with such radiation being all around us. As you say, there's
plenty of workers with daily exposure who do not have significantly
higher cancer profiles than the public at large.
I would caution, however, that the cancer-causing properties of
EM radiation are only ONE potential pathological pathway. In other
words, cancer is not the only way that EM radiation can effect
There are numerous recent peer-reviewed studies (the abstracts
of which a google search can locate) which look at the effects
of EM radiation on biological systems and how EM radiation effects
the production and use of histamines, a ubiquitous protein type
that has important functions in the body's immune system, brain
function, and gastro-intestinal tract. Even if these effects,
once sorted out, turn out to be non-permanent, EM energy may still
affect our bodies adversely during such exposure.
I offer this as straight-forward advice to the moderators of a
great site: there's nothing worse the pronouncing something "safe"
only to find out later that the proper statement should have carried
a caveat. So, safe compared to what? -Perhaps: "...EM radiation
is non-carcinogenic" is a more adequately supported conclusion.
-Just my two cents for free, because a lot of things have been
pronounced safe until science later realized how they had potential
Before we get on with the original
content on this page, here's an interesting fact about this page.
One month back in 2008 this page got numerous hits, so it stood
out in the top ten Microwaves101 pages. We don't often
track the stats (who's got time?), but that month we looked
at page views by country, just to see where the interest was coming
from. Almost all of the hits came from the Islamic Republic of Iran.
We wonder they were up to...
Now back to our original thoughts
on the subject... words we may have to one day eat!
Believe it or not, this is a
frequently asked question at this web site.
Or maybe it is a "frequency asked question". Time to put
the rumors to bed, you scared-i-cats… your cell phone, your microwave
oven, and the neighborhood cell towers are not going to hurt you.
Or cause another Godzilla attack. Sorry.
Disclaimer: this information
we provide is for your reference, and is not meant to stand up in court against
attacks from some tricky lawyer.
Here's two relevant government
bulletins on the subject:
and Answers about Biological Effects and Potential Hazards of
Radiofrequency Electromagnetic Waves
(by the FCC)
of Public Health Concerns Associated with Pave Paws Radar Installations
(by Massachusetts Department of Health)
Some of this info on this page
was found in Introduction to Microwaves, by Fred E. Gardiol.
Merci! Not bad for a French speaking Swiss!
There are people on jobs that
get thousands of times higher exposure levels that the rest of us
get. If microwave radiation was as deadly as some fools would have
you believe, there would be a steady line of cell tower workers,
radar operators, and RF lab technicians all taking an early dirt
nap. There is no evidence that this is the case. Speaking of cases,
how come television lawyer James
R. Sokolove doesn't advertise he'll take on electromagnetic
radiation liability cases? Maybe he's smarter than he looks. It
would be a losing proposition.
Ionizing versus non-ionizing
Microwave energy is non-ionizing
electromagnetic radiation. Ionizing radiation messes up molecules,
non-ionizing radiation merely heats them. You heat your body every
day when you take a shower with more energy than your cell phone
could ever muster. Ionizing radiation starts at ultraviolet frequencies
(UV), and includes X-rays and gamma rays, as you go up the scale
of deadliness. The effects of gamma rays are what
changed Dr. Bruce Banner into The Amazing Hulk; if you are worried
about gamma rays buy yourself a Geiger counter.
Here's a figure that we shamelessly
stole from one of the government publications. Notice that ionizing
radiation is higher in frequency than visible light. Microwave radiation
is far below visible light; indeed, there is a huge band of infrared
between the two. No one worries much about the infrared food warmer
and its effect on cafeteria workers, do they?
Electromagnetic energy is carried
by photons. The higher the frequency, the higher the energy in each
photon. When a certain energy level is reached, the photon has enough
energy to knock off electrons from molecules that it encounters.
At this point it is called ionizing radiation. The critical energy
level is 10 electron volts (eV). One Joule is 6.2x10E18 electron
volts, so a single electron volt is immeasurably small. Here's how
to calculate the energy of a photon, depending on its frequency:
h=Planck's constant = 6.626E-34
For the ISM band (2.45 GHz) where
your microwave oven operates, energy of each photon is therefore
0.00001 electron volts. The power needed to ionize a molecule is
one million times higher than this, so it simply won't happen.
Sunlight is far higher in frequency
than microwaves, it doesn't penetrate the body, so it is more dangerous
at the same power level. Sunlight provides a power level of 100
mW/cm2 during the summer months, mostly infrared, but with some
visible and ultraviolet energy. The cause and effect of skin cancer
is well known, it's the higher frequency UV light that is going
to kill you. This is why sunblock that advertises "blocks UV
rays" is a good thing!
Tanning beds do far more damage
than microwaves. What is wrong with people, why do you need so badly
to change your skin color? Please consider interracial marriage
so your kids don't have to participate in this ridiculous and injurious
clarification on ionizing versus non-ionizing radiation came from
You refer to X-rays and
gamma-rays as "ionizing radiation" (as opposed to "non-ionizing
radiation") and you are absolutely correct in doing so. You
are absolutely correct because you are an Emag / microwave / RF
guy (just like me). Those radiation / nuke / physicist guys, however,
might tell you that X-rays and gamma rays are "indirectly
ionizing radiation" (as opposed to "directly ionizing
radiation"). "Directly" ionizing radiation is a
charged particle that hits you and BLAM the charged particle is
an ion that is now inside you. "Indirectly" ionizing
is a neutral particle or a high energy photon (neither have charge)
and BLAM it knocks some electrons loose that were already inside
you to begin with but made some ions and has the same effect.
Microwave exposure levels
A safety factor of 10 applied
to the solar radiation level has been widely adopted for RF radiation,
the standard is 10 mW/cm2 maximum. This standard applies to continuous
exposure; you can get whacked with higher power for short time with
no permanent effects.
Microwave radiation exposure
is often expressed in terms of incident power density, in mW/cm2.
The following table shows the effects of exposure to certain power
levels, without time limit:
Long-term effect on human
Accepted standard for microwave
Accepted standard for maximum
continuous exposure to radiated emissions (cell phones, etc.)
You can feel heat
Cataracts can be produced
Summer sunlight is at
Pain is induced
Set the timer, lasagna
in five minutes!
Exposure to higher power levels
has been shown to cause cataracts. How do we know this? During WWII,
there were no guidelines for how much radiation a radar operator
could take. Solders and sailors were exposed by radars. At a power
level of 1W/cm2, pain is induced, so their medical problems were
caused by radiation below that level. Thanks to these guinea pigs,
we know where the limit is. If anyone has a good "radar burn"
story they want to share, send it in and we'll send you a free gift!!!
phones can muster 2 watts. If the antenna was right next to
your head, and half the power went into your skull, maybe a power
level of 100 mW/cm2 could be produced, but we doubt it. Certainly
this power level will never heat up your eyeballs, unless you hold
the antenna over your eye when you talk. If you suffer from cataracts,
you didn't get them from Lucky Goldstar. Many modern phones pump
up the power in areas of low signal quality, so if you really want
to minimize your exposure, then consider 1. going outside when you
are calling, 2. talking less, listening more, and 3. moving closer
to the cell tower! But wait, this correction came from Rick. Even
if you are just listening, your cell phone is transmitting.
Cell phones are full-duplex
devices. The base station and your cell antenna are transmitting
at all times during a call... on a long-distance call, there is
a delay from when you speak and the other party acknowledges you
that makes you believe there is only half-duplex transmission.
Thanks for setting us straight!
Now, here's some thoughts on
the topic from Mike:
Read your article on Biological
Effects of Microwave Radiation. Very informative, however you
are incorrect when you say all cell phone are full duplex. The
GSM type cell phone systems (ATT , ALTEL etc.) are not full duplex.
WCDMA, CDMA 2000 Cell phone systems are full duplex (Verizon Sprint
One of these day's we'll create
a separate page on this topic...
For July 2013, here are some further comments from Korkut:
This saves network noise level low and keeps the batteries running longer.
The above information is correct but lacking a certain detail that makes the difference. There are typically two types of transmission between cell phone and the cell antenna: a. signalling b. data/voice transmission. When it is voice transmission, there are 20 ms sampling windows and if there is silence or a certain sound form (say vowel "e" as in "seed") the phone sends only one short message that the former 20 sec window is repeated. If it is silence, it may not even send anything but that it is silence signal and the transcoder in the switching part generates a hush sound for ambient comfort. And this messages are generally sent at signalling channels not in traffic channels. So in short, the mobile phone may be transmitting at all times but not all the time.
No study has proven that RF radiation
at less than 10 mW/cm2 could cause cancer. It is possible that a
cell phone were near enough to male genitals, temporary sterility
could be caused. When your phone is not placing a call but just
left on, it still needs to communicate to a nearby tower every two
or so minutes just so the phone company knows where to find you.
If you have your phone in your pocket all day, you will be radiated
(of course not as much as when connected to a call). In any case,
there is no shortage of people on the planet, so a little temporary
sterility isn't a bad thing, just don't blame this biological problem
on your phone.
Microwave ovens are allowed to
leak 5 mW/cm2 at a distance of 2 inches away. Power level will drop
off as the square of the distance, so 20 inches away it can be no
more than 0.05 mW/cm2.
Cell towers will never put out
anywhere near 10 mW/cm2 to pedestrians near by. Maximum effective
radiated power (ERP) is on the order of 100 watts, but remember,
ERP includes antenna gain; the actual power that is radiated is
on the order of a few watts. By the time it reaches pedestrians,
out at 100 meters for example, the power density is no more than
Pacemakers are designed to handle
10 mW/cm2, no problemo.