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The American Cancer Society
Radiation is the emission (sending
out) of energy from any source. X-rays are an example of radiation, but so is
the light that comes from the sun and the heat that is constantly coming off
our bodies.
When talking about radiation and
cancer, many people think of specific kinds of radiation such as x-rays or the
radiation made by nuclear reactors.
But there are other types of
radiation that act differently.
Radiation exists across a spectrum
from very low-energy (low-frequency) radiation to very high-energy
(high-frequency) radiation. This is sometimes referred to as the electromagnetic
spectrum.
The electromagnetic spectrum
illustration below shows all of the possible frequencies of electromagnetic
energy.
It ranges from extremely low
frequencies (such as those from power lines) to extremely high frequencies
(x-rays and gamma rays), and includes both non-ionizing and ionizing radiation.
Examples of high-energy radiation
include x-rays and gamma rays.
These rays, as well as some higher
energy UV radiation, are forms of ionizing
radiation, which means they have enough energy to remove an electron from
(ionize) an atom.
This can damage the DNA (genes) inside of cells, which can sometimes result in cancer.
What is
radiofrequency (RF) radiation?
Radiofrequency (RF) radiation, which
includes radio waves and microwaves, is at the low-energy end of the
electromagnetic spectrum.
It is a type of non-ionizing
radiation. Non-ionizing radiation does not have enough energy to remove
electrons from an atom.
Visible light is another type of
non-ionizing radiation. RF radiation has lower energy than some other
types of non-ionizing radiation, like visible light and infrared, but it has
higher energy than extremely low-frequency (ELF) radiation.
If RF radiation is absorbed by the
body in large enough amounts, it can produce heat. This can lead to burns and
body tissue damage.
Although RF radiation is not thought
to cause cancer by damaging the DNA in cells the way ionizing radiation does,
there has been concern that in some circumstances, some forms of non-ionizing
radiation might still have other effects on cells that might somehow result in
cancer.
How are people
exposed to RF radiation?
People can be exposed to RF radiation
from both natural and man-made sources.
Natural sources include:
· Outer space and the sun
· The sky – including lightning strikes
· The earth itself – most radiation from the earth is infrared,
but a tiny fraction is RF
Man-made RF radiation sources
include:
· Broadcasting radio and television signals
· Transmitting signals from cordless telephones, cell phones and cell phone towers, satellite phones, and 2-way
radios
· Radar
· WiFi, Bluetooth® devices, and smart meters
· The heating of body tissues to destroy them in medical
procedures
· “Welding” pieces of polyvinyl chloride (PVC) using certain
machines
· Millimeter wave scanners (a type of full body scanner used for
security screening)
Some people can have significant RF
exposure as part of their jobs. This includes people who maintain antenna
towers that broadcast communication signals and people who use or maintain
radar equipment.
Most people are exposed to much lower
levels of man-made RF radiation every day due to the presence of RF signals all
around us.
They come from radio and television
broadcasts, WiFi and Bluetooth devices, cell phones (and cell phone towers),
and other sources.
Some common uses of
RF radiation
Microwave ovens
Microwave ovens work by using very
high levels of a certain frequency of RF radiation (in the microwave spectrum)
to heat foods.
When food absorbs microwaves, it
causes the water molecules in the food to vibrate, which produces heat.
Microwaves do not use x-rays or gamma rays, and they do not make food
radioactive.
Microwave ovens are designed so that
the microwaves are contained within the oven itself. The oven only makes
microwaves when the door is shut and the oven is turned on.
When microwave ovens are used
according to instructions, there is no evidence that they pose a health risk to
people.
In the US, federal standards limit the
amount of RF radiation that can leak from a microwave oven to a level far below
what would harm people.
Ovens that are damaged or modified,
however, could allow microwaves to leak out, and so could pose a hazard to
people nearby by potentially causing burns.
Full-body security
scanners
In many airports in the United
States, the Transportation Security Administration (TSA) uses full body
scanners to screen passengers.
The scanners currently used by the
TSA use millimeter wave imaging. These scanners send out a small
amount of millimeter wave radiation (a type of RF radiation) toward the person
in the scanner.
The RF radiation passes through
clothing and bounces off the person’s skin, as well as any objects under the
clothes. Receivers sense the radiation and create an image of the outline of
the person.
Millimeter wave scanners do not use
x-rays (or any other kind of high-energy radiation), and the amount of RF
radiation used is very low.
According to the US Food and Drug
Administration (FDA), these scanners have no known health effects. However, TSA
often allows people to be screened in a different way if they object to
screening with these scanners.
Cell phones and
cell phone towers
Cell phones and cell phone towers
(base stations) use RF radiation to transmit and receive signals.
Some concerns have been raised that
these signals might increase the risk of cancer, and research in this area
continues. For more information, see Cellular Phones and Cell Phone Towers.
Does RF radiation
cause cancer?
Researchers use 2 main types of
studies to try to determine if something might cause cancer:
·
Studies done in the lab studies
·
Studies looking at groups
of people
Often neither type of study provides
enough evidence on its own, so researchers usually look at both lab-based and
human studies when trying to figure out if something causes cancer.
The following is a brief summary
of some of the major studies that have looked at this issue to date. However,
this is not a comprehensive review of all studies that have been done.
Studies done in the
lab
RF waves don’t have enough energy to
damage DNA directly. Because of this, it’s not clear how RF radiation might be
able to cause cancer.
Some studies have found possible
increased rates of certain types of tumors in lab animals exposed to RF
radiation, but overall, the results of these types of studies have not provided
clear answers so far.
A few studies have reported evidence
of biological effects that could be linked to cancer, but this is still an area
of research.
In large studies published in 2018 by
the US National Toxicology Program (NTP) and by the Ramazzini Institute in
Italy, researchers exposed groups of lab rats (as well as mice, in the case of
the NTP study) to RF waves over their entire bodies for many hours a day,
starting before birth and continuing for at least most of their natural lives.
Both studies found an increased risk
of uncommon heart tumors called malignant schwannomas in male rats, but not in
female rats (nor in male or female mice, in the NTP study).
The NTP study also reported possible
increased risks of certain types of tumors in the brain and in the adrenal
glands.
While both of these studies had
strengths, they also had limitations that make it hard to know how they might
apply to humans being exposed to RF radiation.
A 2019 review of these two studies by
the International Commission on Non-Ionizing Radiation Protection (ICNIRP)
determined that the limitations of the studies didn’t allow conclusions to be
drawn regarding the ability of RF energy to cause cancer.
Still, the results of these studies
do not rule out the possibility that RF radiation might somehow be able to
impact human health.
Studies in people
Studies of people who may have been
exposed to RF radiation at their jobs (such as people who work around or with
radar equipment, those who service communication antennae, and radio operators)
have found no clear increase in cancer risk.
A number of studies have looked for a
possible link between cell phones and cancer. Although some studies have shown
a possible link, many others have not.
For many reasons, it is hard to study
if there might be a link between cell phones and cancer, including the
relatively short time that cell phones have been in widespread use, changes in
the technology over time, and difficulty in estimating each person’s exposure.
The topic of cell phones and cancer
risk is discussed in detail in Cellular (Cell) Phones.
What do expert
agencies say?
The
American Cancer Society (ACS) does not have any official position or statement
on whether or not radiofrequency radiation from cell phones, cell phones
towers, or other sources is a cause of cancer.
ACS generally looks to other expert
organizations to determine if something causes cancer (that is, if it is a
carcinogen), including:
· The International Agency for Research on Cancer (IARC),
which is part of the World Health Organization (WHO)
· The US National Toxicology Program (NTP), which is
formed from parts of several different government agencies, including the
National Institutes of Health (NIH), the Centers for Disease Control and
Prevention (CDC), and the Food and Drug Administration (FDA)
Other major organizations might also
comment on the ability of certain exposures to cause cancer.
Based on a review of studies
published up until 2011, the International
Agency for Research on Cancer (IARC) has classified RF radiation as
“possibly carcinogenic to humans,” based on limited evidence of a possible
increase in risk for brain tumors among cell phone users, and inadequate
evidence for other types of cancer. (For more information on the IARC
classification system, see Known and Probable Human Carcinogens.)
More recently, the US Food and Drug Administration (FDA) issued
a technical report based on results of studies published between 2008 and 2018,
as well as national trends in cancer rates.
The report concluded: “Based on the studies that are described in
detail in this report, there is insufficient evidence to support a causal
association between radiofrequency radiation (RFR) exposure and [tumor
formation].”
So far, the National Toxicology Program (NTP) has
not included RF radiation in its Report on Carcinogens, which lists
exposures that are known to be or reasonably anticipated to be human
carcinogens. (For more on this report, see Known and Probable Human Carcinogens.)
According to the US Federal
Communications Commission (FCC):
“[C]urrently no
scientific evidence establishes a causal link between wireless device use and
cancer or other illnesses. Those evaluating the potential risks of using wireless
devices agree that more and longer-term studies should explore whether there is
a better basis for RF safety standards than is currently used.”
How can I avoid
exposure to RF radiation?
Because sources of RF radiation are
so common in the modern world, there is no way to completely avoid exposure to
it.
There are some ways you can lower
your exposure to RF radiation, such as:
· Avoiding jobs with increased RF exposure
· Limiting the time you spend near appliances, equipment, and
other devices (such as WiFi routers) that give off RF radiation
· Limiting the time you spend with a cell (mobile) phone placed
against your ear (or close to another part of your body)
Still, it isn’t clear that doing these things will be helpful in terms of health risks.
The
American Cancer Society medical and editorial content team
Our team is made up of doctors
and oncology certified nurses with deep knowledge of cancer care as well
as journalists, editors, and translators with extensive experience in medical
writing.
At the American Cancer Society, we're on a
mission to free the world from cancer. Until we do, we'll be funding and
conducting research, sharing expert information, supporting patients, and
spreading the word about prevention. All so you can live longer — and better.
Whether we're working in a community near
you or one halfway around the world, our mission remains the same: to save
lives. See what we've been up to lately — and get to know the American Cancer
Society a little bit better.
https://www.cancer.org/cancer/cancer-causes/radiation-exposure/radiofrequency-radiation.html
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