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 smartphones) 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 person’s 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.