Brain Cancer Risk and Smartphones
Smartphones are with us 24/7 now, even helping collect data while we sleep, as we explored in the last issue. So it is welcome news that decades-old, quite persistent concerns over cell phone use and brain cancer risk are, according to the most recent data, still unfounded.
An unpublished joint effort by British government officials and the telecommunications industry to correlate cell phone use with brain cancer risk has failed to turn up a link. The £13.6 million Mobile Telecommunications and Health Research (MTHR) research program was the U.K.’s largest to look at the possible health risks associated with mobile phone technology.
Cell phones emit radio frequency (RF) energy, and the concern over their use may have emerged from this fact because this type of non-ionizing electromagnetic radiation can be absorbed by human tissue. We hold our phones to our heads several times per day, so it was never an unreasonable concern—particularly in the early days of cell phones when little was known about long-term use.
Fast forward 11 years, and the data seems to strongly reflect that the phones are safe. Earlier this year, the chairperson of the MTHR stated, "This independent program is now complete, and despite exhaustive research, we have found no evidence of risks to health from the radio waves produced by mobile phones or their base stations."
The other type of electromagnetic radiation is known as ionizing radiation. This type includes x-rays, radon and cosmic rays. Exposure to ionizing radiation, for example during radiation therapy, is known to increase the risk of cancer. However, although many studies have examined the potential health effects of non-ionizing radiation from radar, microwave ovens and other sources, there is currently no consistent evidence that non-ionizing radiation increases cancer risk.
The only known biological effect of RF energy is heating. The ability of microwave ovens to heat food is one example of this effect. RF exposure from cell phone use does in fact cause heating, but it isn’t sufficient to measurably increase body temperature. Perhaps more alarmingly, a recent study showed that when people used a cell phone for 50 minutes, brain tissues on the same side of the head as the phone’s antenna metabolized more glucose than did tissues on the opposite side of the brain. The researchers noted that the results were preliminary, and possible health outcomes from this increase in glucose metabolism are still unknown.
It is generally accepted that damage to DNA is necessary for cancer to develop. However, RF energy, unlike ionizing radiation, does not cause DNA damage in cells, and it has not been found to cause cancer in animals or to enhance the cancer-causing effects of known chemical carcinogens in animals.
Brain cancer incidence and mortality rates have changed little in the past decade. The National Cancer Institute writes that in the U.S., 23,130 new diagnoses and 14,080 deaths from brain cancer were estimated for 2013. The five-year relative survival for brain cancers diagnosed from 2003 through 2009 was 35%. This number is arrived at by comparing the cancer patient with the survival of a person of the same age and sex who does not have cancer.
The NCI notes, “The risk of developing brain cancer increases with age. From 2006 through 2010, there were fewer than five brain cancer cases for every 100,000 people in the U.S. under age 65, compared with approximately 19 cases for every 100,000 people ages 65 or older.”
In theory, children have the potential for greater risk than adults for developing brain cancer from cell phones. Their nervous systems are still developing, and so more vulnerable to factors that may cause cancer. They also have smaller heads than adults and therefore greater proportional exposure to the phone’s field of RF radiation.
So far, the data from studies in children with cancer do not support an increased-risk theory. The first published analysis came from a large case-control study in Denmark, Sweden, Norway and Switzerland. The study included children who were diagnosed with brain tumors between 2004 and 2008, when their ages ranged from seven to 19. Researchers did not find an association between cell phone use and brain tumor risk in this group of children. However, they did not rule out the possibility of a slight increase in brain cancer risk—data gathered through prospective studies rather than participant surveys will be key in clarifying whether there is an increased risk.
According to the NCI, an earlier case-control study in the U.S. was unable to demonstrate a relationship between cell phone use and glioma or meningioma. The amount of radio frequency energy a cell phone user is exposed to depends on the technology of the phone, the distance between the phone’s antenna and the user, the extent and type of use, and the user’s distance from cell phone towers. Another study published in 2010 in BMJ found no link between living proximity to base stations and perinatal leukemia risk.