So far, the scientific evidence shows it is unlikely that
mobile phones could increase the risk of brain tumours, or any other type of
cancer. But we do not know enough to completely rule out a risk. In 2011, the International
Agency for Research on Cancer classified mobile phones for the first time in
their ‘gold-standard’ rating system. They said the devices could ‘possibly’
cause cancer in humans (group 2B), but there wasn’t enough evidence to come to
a clear conclusion.
Cell phones (including smart phones) give off a form of
energy known as radiofrequency (RF) waves, so some concerns have been raised
about the safety of cell phone use. With respect to cancer, concern focuses on
whether cell phones might increase the risk of brain tumours or other tumours
in the head and neck area.
Cell phones work by sending signals to (and receiving them
from) nearby cell towers (base stations) using RF waves. This is a form of
electromagnetic energy that falls between FM radio waves and microwaves. Like
FM radio waves, microwaves, visible light, and heat, RF waves are a form of
non-ionizing radiation. They don’t have enough energy to cause cancer by
directly damaging the DNA inside cells. RF waves are different from stronger (ionizing)
types of radiation such as x-rays, gamma rays, and ultraviolet (UV) light,
which can break the chemical bonds in DNA.
At very high levels, RF waves can heat up body tissues.
(This is the basis for how microwave ovens work.) But the levels of energy
given off by cell phones are much lower, and are not enough to raise
temperatures in the body.
How are people
exposed?
The RF waves from cell phones come from the antenna, which
is part of the body of a hand-held phone. The waves are strongest at the antenna
and lose energy quickly as they travel away from the phone. The phone is
typically held against the side of the head when in use. The closer the antenna
is to the head, the greater a people expected exposure to RF energy. The body
tissues closest to the phone absorb more energy than tissues farther away.
Many factors can
affect the amount of RF energy to which a person is exposed, including:
• The average number of cell phone calls per day, week, or
month (frequency)
• The person is using the speaker mode on the phone or a
hands-free device. Using one of these allows the phone to be held away from the
head.
• The distance and path to the nearest cell phone tower.
Cell phones adjust their power to use the minimum amount for a good signal.
Being farther away from the tower requires more energy to get a good signal, as
does being inside a building.
• The amount of cell phone traffic in the area at the time.
Higher traffic may require more energy to get a good signal.
• The model of phone being used. Different phones give off
different amounts of energy.
So far, studies have indicated that using these phones for
about 10 years is unlikely to cause cancer. But we cannot be completely sure
about their long-term effects. There still aren’t any good explanations for how
mobile phones could cause cancer. The radiofrequency electromagnetic radiation
they transmit and receive is very weak. This radiation does not have enough
energy to damage DNA, and cannot directly cause cancer.
What can mobile users
do to reduce their exposure to radiofrequency energy?
• Reserve the use of cell phones for shorter conversations
or for times when a landline phone is not available.
• Use a device with hands-free technology, such as wired
headsets, which place more distance between the phone and the head of the user.
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