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WHO on mobile phone risk....
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发表时间:2014-12-07
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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.

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.

For more information contact:

WHO Media centre
Telephone: +41 22 791 2222
E-mail: [email protected]

Related link
Interphone study on mobile phone use and brain
cancer risk [pdf 176kb]
The International Electromagnetic Fields Project
Electromagnetic fields: base stations and wireless
technologies
Electromagnetic fields: electromagnetic
hypersensitivity
WHO research agenda for electromagnetic fields
Media centre Fact sheets
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© WHO 2014

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