Do you know anyone who doesn’t have a cell phone? Chances are that, if you’re in lecture while you’re reading this, most students are either on their cell phones or have them out on their desks. Despite some professors’ rules to keep cell phones turned off and in backpacks, students still use them. UC Davis students are not alone; statistics from June 2011 show that nearly everyone in the United States has a cell phone.
Such wide use of cell phones is why it was hard to escape the headline “WORLD HEALTH ORGANIZATION SAYS CELL PHONES CAUSE CANCER!!!” last May and June. I saw the story posted on Twitter, Reddit and Facebook multiple times. CNN, BBC and countless other networks all featured the story on their sites and in their broadcasts. Their headlines sounded slightly less hysterical but stated the same thing.
Now, a second question: do you know anyone who got rid of their cell phone as a result? Either no one cares whether they get brain cancer, or everyone knew the story was a ridiculous exaggeration.
It looks like it was the latter. Most media reports left out the details of what exactly this declaration meant. The International Agency for Research on Cancer (IARC), a part of the World Health Organization (WHO), classified cell phones as part of Group 2B, which is “possibly carcinogenic to humans.”
According to the IARC information sheet, Group 2B “is used for agents for which there is limited evidence of carcinogenicity in humans and less than sufficient evidence of carcinogenicity in experimental animals. It may also be used when there is inadequate evidence of carcinogenicity in humans but sufficient evidence of carcinogenicity in experimental animals.”
This flood of jargon basically means that if a couple of studies found even a tiny risk of cancer for people or animals exposed to a certain substance or device, they are classified into Group 2B. This group includes asphalt and diesel fuel.
The most recent of a large number of health studies on cell phones has been a Danish study that looked at 420,000 cell phone subscribers and found no correlation with cell phone subscription and incidence of brain cancers, even for those who had been subscribers for over 10 years.
The problem with the media focusing on only one science story at a time is that it gives the impression that this one study is all that separates doctors from thinking that cell phones actually cause cancer. It also makes people think that any weakness in this one study means that there may actually be a cancer risk.
The Danish study does have weaknesses, the way every study does. The Danish study is a cohort study, which means researchers follow a group of people over time and study the incidence of cancer between different populations (in this case, one population has cell phones and the other does not).
Fortunately, scientists do not rely upon a single study. In order to consider findings valid, there has to be multiple studies from many independent researchers looking at large groups of people. A single study doesn’t tell researchers much; until the findings are replicated and expanded, researchers consider the question open.
The question of the health effects of cell phones has actually been researched a lot in the past couple of decades. The majority of large studies have found no risk at all because the electromagnetic radiation has too low of a frequency to damage DNA, which is what is required to increase rates of cancer. Sometimes, one study will find a slightly increased risk of brain cancer in a certain population, such as children who began using cell phones before the age of 20. Later studies then disprove that link.
Why the inconsistency? It’s called statistical error: sometimes, by chance, researchers collect data that is different from the actual value. Using a larger sample decreases the possibility of this kind of error, but it can still happen. That’s why researchers will often repeat studies that they or their colleagues already did, so that they can decrease the possibility of error as much as possible.
So far, the research says that you have nothing to fear from your cell phone. Just make sure that if you’re in class, turn it off or keep it on silent; the real risk is that if it vibrates during class, the professor may snap out of frustration.
AMY STEWART can be reached at email@example.com, or you can call her on her cell phone.