Can a smartphone cause brain tumors? Robert Matthews clarifies the facts behind the headlines.
Newspapers around the world have issued a series of articles addressing the health risks associated with one of the most popular technologies of all time—cell phones. The International Agency for Research on Cancer (IARC), part of the World Health Organization, issued a warning: according to a number of experts from this agency, there are grounds to believe that mobile phones may still cause cancer in humans. Such a statement could not be ignored. Within days, influential American congressmen demanded a review of existing safety standards for cell phones, and the Taiwanese government announced the possibility of banning the use of mobile phones in schools. The European Council also presented a draft document proposing a similar ban for all its member countries. However, other organizations have sought to distance themselves from the IARC report. The British Health Protection Agency and the British Cancer Research Center insist that there is no compelling scientific evidence linking the risk of cancer to mobile phones. So, who is right? Should we protect ourselves from the electromagnetic radiation of our phones, or should we disregard the latest statements as another medical scare?
Are smartphones dangerous?
This question has plagued cell phone manufacturers for many years. Headlines about potential health risks first emerged in 1992 when Susan Reynard’s husband from Florida filed a lawsuit against NEC phone manufacturer and GTE Mobilnet. He claimed that the mobile phone caused or accelerated the growth of a brain tumor, which led to his wife’s death. This case was reviewed for several years until it was closed with a typical motivation for such cases: due to a lack of compelling scientific evidence.
Since then, researchers have not lacked attempts to find these grounds. Over the years, numerous studies on the potential link between health and the use of mobile phones have been published. However, the overall picture obtained disappoints with its lack of persuasiveness.
In a Danish study completed in 2006, over 420,000 mobile phone users were observed for over 20 years, but no connections with brain cancer were found. This result was confirmed last year as part of the Interphone study, which compared mobile phone use in healthy individuals and 5,000 brain cancer patients from 13 countries. However, Swedish researchers led by Dr. Lennart Hardell from the University Hospital in Orebro have repeatedly claimed to have found evidence of a link between brain cancer and cell phones, with the risk increasing with the frequency of their use. In their latest work published in 2010, the group reports a 2-3 fold increase in such risk among those who have been using mobile phones for a long time.
Which studies to believe? Dr. Mike Clark, a specialist at the Health Protection Agency dealing with the impact of radio waves on the human body, finds it difficult to answer this question because practically every one of these studies can be criticized. “In Hardell’s work, the time of mobile phone use was determined by the words of relatives of the patients,” Clark explains. “This means that memory-related witness errors are possible, which cannot be accounted for.” Systematic errors are one of the pitfalls of all such studies, as people poorly remember what they did in previous years. Distortions can be very significant.
Plausibility is another big question mark in the debate over the danger of cell phones. Despite years of research, no one has yet offered a compelling explanation of how exactly a mobile phone can damage living tissues and trigger cancer.
Risk perception specialist Adam Burgess from the University of Kent in the UK claims that the public is being misled by discussions about the “radiation” emitted by mobile phones. He explains that while handsets emit electromagnetic radiation, it is not the ionizing radiation whose energy is sufficient to eject electrons from atoms. The energy of the waves emitted by phones is many times lower than the level required to break interatomic bonds. Therefore, the radiation from cell phones cannot, like ionizing radiation, cause damage to living cells. Hence the deep doubts about its ability to cause cancer.
The contradictory and scientifically unreliable evidence has led the IARC to declare mobile phones only a possible cause of cancer, placing them in this sense lower than not only proven but even probable causes. This means that cell phones are classified in the same category of carcinogenicity as coffee and talcum powder—there is no reason for nightmares about mobile phones.
David Spiegelhalter, professor of public understanding of risk at the University of Cambridge, goes further and notes that contradiction and unreliability are classic signs of illusory health risks. “You can always use the standard argument that the absence of evidence does not mean evidence of absence, but this usually indicates a very low risk not worth worrying about,” he notes. He adds that many studies deal with old models of handsets, the radiation power of which is significantly higher than that of modern ones. Thus, there are no reliable data on the long-term risks associated with phones.
On the Benefit of Risk
To address such misunderstandings, Spiegelhalter, together with Kevin McConway, a professor of applied statistics at The Open University (UK), developed a guide for health risk assessment, emphasizing the need to consider all aspects of the issue. “People themselves evaluate the results of research, and when it comes to mobile phones, most simply don’t think about some obvious things,” says Professor Spiegelhalter.
Despite this, many researchers believe that the study of the issue should continue until all ambiguity is eliminated. Soon after the publication of the IARC report, a group led by Dr. Angelo Levia from the Padua Medical School in Italy published alarming facts indicating that studies that failed to detect a link between mobile phones and cancer often make serious methodological errors leading to systematic errors, and that moreover, these studies are often funded by the mobile phone industry. If the results of the highest quality studies are combined, according to the Italian authors, the risk of brain tumors becomes obvious: for those who use a phone for a long time, it is twice as high as the normal level.
But even if this is the case, many specialists still disagree with claims that using cell phones is associated with a “very high” risk of cancer. Brain tumors are relatively rare and occur in about one in 20,000 people per year. Doubling the risk will result in only two out of 20,000.
Clark believes that by listing mobile phones as a cause of cancer, IARC has not said anything new. “Our advice to avoid excessive prolonged use of phones, especially by children, has not changed, as the possibility of long-term effects still remains.”
The World Health Organization plans to continue researching the risks associated with ten years of phone use. However, many scientists suspect that there will never be a definitive answer to the question of whether mobile phones are safe, as there is always uncertainty about how long and how intensively people use them. Clark believes that it is necessary to focus on much more serious dangers. “The threat to life from cell phones exists,” he says, “but it has a much more obvious cause — talking on the phone while driving.”
Reasons for Concern
Should you pay attention to the latest health scare? Professors David Spiegelhalter and Kevin McConway explain which questions to ask and which ones not to.
Does the article you’re reading only report the results of a single scientific study?
Science is based on accumulating evidence, so a single study is just one step forward. The most serious recommendations are found in reviews covering multiple studies, especially those issued by the Cochrane Collaboration, an international network of experts that evaluates medical research.
Was there an experiment?
We can only be confident that certain things cause cancer if properly designed laboratory experiments show how it happens. Or it should be randomized trials: for example, the impact of eating one bacon sandwich a day on health is studied by randomly assigning people to groups, one of which eats bacon while the other does not, followed by observation. If trials are not randomized, differences in cancer rates between groups may be caused by some other factor. For example, one group may be older than the other. There are statistical methods to account for such effects, but they don’t always work.
How many people were studied?
There should be enough participants in the study. However, there is no guarantee of finding the truth. Various systematic errors are possible. People with brain tumors overestimate their past mobile phone use. So, you should always ask: could something else explain the results?
What is the source of the report?
Can you trust what’s written? Publications in peer-reviewed journals are more reliable, but even they are not flawless. For example, the medical journal The Lancet published a later discredited study on the link between vaccination and autism.
Why am I reading this?
Organizations need publicity, and editors choose sensational topics. And even if the importance of the article is not exaggerated, the press tends to simplify details. If the article sounds too sensational, consider whether the claims it contains are accurate.
What am I not being told?
Scary stories tell of tragedies that have already happened. If everything is fine, newspapers won’t write about it. Even scientific journals tend to publish sensational results and avoid studies that contradict commonly accepted “scare stories.”
Is this study applicable to me?
This could be a study conducted on rats in the first stage. It’s unclear how applicable it is to humans. If it’s a study on humans, are they similar to you, for example, in age or living conditions? Perhaps they are people exposed to strong atypical influences? These circumstances should be taken into account.
Is the discussed risk significant?
The headline may talk about an “increase in risk,” but keep in mind that even a doubled small risk remains small. It’s much easier to judge risks when the consequences for 100 people similar to you are described.
Do the benefits outweigh the potential risk?
A 20% increase in the risk of colon cancer from daily consumption of a bacon sandwich will increase the overall risk from 5 in 100 to 6 in 100. Perhaps you are willing to take the risk for the pleasure? (Don’t think that we recommend having bacon sandwiches for lunch!)