Media centre
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 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.
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.
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: mediainquiries@who.int
Related link
Interphone study on mobile phone
use and brain cancer risk [pdf
176kb]1, 212 The International Electromagnetic
Fields Project
Electromagnetic fields: base
stations and wireless technologies
Electromagnetic fields:
electromagnetic hypersensitivity
WHO research agenda for
electromagnetic fields