Most of us depend on cell phones every day. Some people wonder if cell phones can cause health problems. Here’s what you should know about cell phones and your health.
Can using a cell phone cause cancer?
There is no scientific evidence that provides a definite answer to that
question. Some organizations recommend caution in cell phone use. More research
is needed before we know if using cell phones causes health effects.
Do cell phones give off (emit) radiation?
Yes – cell phones and cordless phones use radiofrequency radiation (RF) to
send signals. RF is different from other types of radiation (like x-rays) that
we know can be harmful. We don’t know for sure if RF radiation from cell phones
can cause health problems years later. The International Agency for Research on
Cancer (IARC) has classified RF radiation as a “possible human carcinogen.” (A
carcinogen is an agent that causes cancer.)
Should people stop using cell phones?
At this time we do not have the science to link health problems to cell
phone use. Scientific studies are underway to determine whether cell phone use
may cause health effects. It is also important to consider the benefits of cell
phones. Their use can be valuable in an urgent or emergency situation – and
even save lives.
If you are worried about cell phone use, follow the
tips below.
Why has the information on this page been updated?
CDC has not changed its position on health effects associated with the use
of cell phones. The agency updated these cell phone FAQs in June 2014 as part
of efforts to ensure that health information for the public followed best
practices, including the use of plain, easy-to-understand, language. During
this process, revisions were introduced which inadvertently led some visitors
to the web page to believe that a change in position had occurred. The
corrected FAQs are now available on this page.
CDC announces changes in public health policy and recommendations through
publication in the peer-reviewed literature, usually accompanied by outreach to
partners and a media announcement. We apologize for any confusion that resulted
from our efforts to ensure that agency information is presented in
easy-to-understand language.
Cell phone tips
To reduce radio frequency radiation near your body:
Get a hands-free headset that connects directly to your phone.
Use speaker-phone more often.
In the past, RF interfered with the operation of some pacemakers. If you
have a pacemaker and are concerned about how your cell phone use may affect it,
contact your health care provider.
What research is being done to learn more about cell phones and health?
Scientists are continuing to study the possible health effects of cell
phone use. For example, the World Health Organization (WHO) is currently
looking into how cell phones may affect:
Some types of tumors (a lump or growth)
Our eyes
Sleep
Memory
Headaches
In the News: Acoustic Neuroma
Scientists are looking into a possible link between cell phone use and
certain types of tumor. One type is called an acoustic neuroma (“ah-COOS-tik
nur-OH-ma”). This type of tumor grows on the nerve that connects the ear to the
brain. It doesn’t cause cancer, but it may lead to other health problems, like
hearing loss. Another type scientists are looking into is called a glioma
(“glee-OH-ma”). This is a tumor found in the brain or central nervous system of
the body.
(Page last reviewed: June 9, 2014, Page last
updated: June 9, 2014
Content source: Centers for Disease Control and
Prevention)
參考資料 2, WHO:
Electromagnetic fields and public health: mobile
phones
Fact sheet N°193
Reviewed October 2014
Key facts
Mobile phone use is ubiquitous with an estimated 6.9 billion subscriptions
globally.
The electromagnetic fields produced by mobile phones are classified by the
International Agency for Research on Cancer as possibly carcinogenic to humans.
Studies are ongoing to more fully assess potential long-term effects of
mobile phone use.
WHO will conduct a formal risk assessment of all studied health outcomes
from radiofrequency fields exposure by 2016.
Mobile or cellular phones are now an integral part of modern
telecommunications. In many countries, over half the population use mobile
phones and the market is growing rapidly. In 2014, there is an estimated 6.9
billion subscriptions globally. In some parts of the world, mobile phones are
the most reliable or the only phones available.
Given the large number of mobile phone users, it is important to
investigate, understand and monitor any potential public health impact.
Mobile phones communicate by transmitting radio waves through a network of
fixed antennas called base stations. Radiofrequency waves are electromagnetic
fields, and unlike ionizing radiation such as X-rays or gamma rays, can neither
break chemical bonds nor cause ionization in the human body.
Exposure levels
Mobile phones are low-powered radiofrequency transmitters, operating at
frequencies between 450 and 2700 MHz with peak powers in the range of 0.1 to 2
watts. The handset only transmits power when it is turned on. The power (and
hence the radiofrequency exposure to a user) falls off rapidly with increasing
distance from the handset. A person using a mobile phone 30–40 cm away from
their body – for example when text messaging, accessing the Internet, or using
a “hands free” device – will therefore have a much lower exposure to radiofrequency
fields than someone holding the handset against their head.
In addition to using "hands-free" devices, which keep mobile
phones away from the head and body during phone calls, exposure is also reduced
by limiting the number and length of calls. Using the phone in areas of good
reception also decreases exposure as it allows the phone to transmit at reduced
power. The use of commercial devices for reducing radiofrequency field exposure
has not been shown to be effective.
Mobile phones are often prohibited in hospitals and on airplanes, as the
radiofrequency signals may interfere with certain electro-medical devices and
navigation systems.
Are there any health effects?
A large number of studies have been performed over the last two decades to
assess whether mobile phones pose a potential health risk. To date, no adverse
health effects have been established as being caused by mobile phone use.
Short-term effects
Tissue heating is the principal mechanism of interaction between
radiofrequency energy and the human body. At the frequencies used by mobile
phones, most of the energy is absorbed by the skin and other superficial
tissues, resulting in negligible temperature rise in the brain or any other
organs of the body.
A number of studies have investigated the effects of radiofrequency fields
on brain electrical activity, cognitive function, sleep, heart rate and blood
pressure in volunteers. To date, research does not suggest any consistent
evidence of adverse health effects from exposure to radiofrequency fields at
levels below those that cause tissue heating. Further, research has not been
able to provide support for a causal relationship between exposure to
electromagnetic fields and self-reported symptoms, or “electromagnetic
hypersensitivity”.
Long-term effects
Epidemiological research examining potential long-term risks from
radiofrequency exposure has mostly looked for an association between brain
tumours and mobile phone use. However, because many cancers are not detectable
until many years after the interactions that led to the tumour, and since
mobile phones were not widely used until the early 1990s, epidemiological
studies at present can only assess those cancers that become evident within
shorter time periods. However, results of animal studies consistently show no
increased cancer risk for long-term exposure to radiofrequency fields.
Several large multinational epidemiological studies have been completed or
are ongoing, including case-control studies and prospective cohort studies
examining a number of health endpoints in adults. The largest retrospective
case-control study to date on adults, Interphone, coordinated by the
International Agency for Research on Cancer (IARC), was designed to determine
whether there are links between use of mobile phones and head and neck cancers
in adults.
The international pooled analysis of data gathered from 13 participating
countries found no increased risk of glioma or meningioma with mobile phone use
of more than 10 years. There are some indications of an increased risk of
glioma for those who reported the highest 10% of cumulative hours of cell phone
use, although there was no consistent trend of increasing risk with greater
duration of use. The researchers concluded that biases and errors limit the
strength of these conclusions and prevent a causal interpretation.
Based largely on these data, IARC has classified radiofrequency
electromagnetic fields as possibly carcinogenic to humans (Group 2B), a
category used when a causal association is considered credible, but when
chance, bias or confounding cannot be ruled out with reasonable confidence.
While an increased risk of brain tumors is not established, the increasing
use of mobile phones and the lack of data for mobile phone use over time
periods longer than 15 years warrant further research of mobile phone use and
brain cancer risk. In particular, with the recent popularity of mobile phone
use among younger people, and therefore a potentially longer lifetime of
exposure, WHO has promoted further research on this group. Several studies
investigating potential health effects in children and adolescents are
underway.
Exposure limit guidelines
Radiofrequency exposure limits for mobile phone users are given in terms
of Specific Absorption Rate (SAR) – the rate of radiofrequency energy
absorption per unit mass of the body. Currently, two international bodies 1, 2
have developed exposure guidelines for workers and for the general public,
except patients undergoing medical diagnosis or treatment. These guidelines are
based on a detailed assessment of the available scientific evidence.
WHO'S response
In response to public and governmental concern, WHO established the
International Electromagnetic Fields (EMF) Project in 1996 to assess the
scientific evidence of possible adverse health effects from electromagnetic
fields. WHO will conduct a formal risk assessment of all studied health
outcomes from radiofrequency fields exposure by 2016. In addition, and as noted
above, the International Agency for Research on Cancer (IARC), a WHO
specialized agency, has reviewed the carcinogenic potential of radiofrequency
fields, as from mobile phones in May 2011.
WHO also identifies and promotes research priorities for radiofrequency
fields and health to fill gaps in knowledge through its research agendas.
WHO develops public information materials and promotes dialogue among
scientists, governments, industry and the public to raise the level of
understanding about potential adverse health risks of mobile phones.
Reference:
1 International Commission on Non-Ionizing Radiation Protection (ICNIRP).
Statement on the "Guidelines for limiting exposure to time-varying
electric, magnetic and electromagetic fields (up to 300 GHz)", 2009.
2 Institute of Electrical and Electronics Engineers
(IEEE). IEEE standard for safety levels with respect to human exposure to radio
frequency electromagnetic fields, 3 kHz to 300 GHz, IEEE Std C95.1, 2005.
