During the week of May 22, news dropped about a $25 million government study which finally drew a clear connection between cellphone radiation and tumors present in rats. The implication? Humanity's penchant for using cellphones and other mobile gadgets will lead to higher incidences of cancer and death.
However, these kinds of doom-heralding announcements should always be taken with a grain of salt, particularly when they first start to circulate. And what has been found is that this study does not provide such a clear link between cellphone usage and cancer.
As Aaron Carroll of The New York Times notes, this study has not even been published in any scientific journals and has not yet even been accepted for review by any editors.
The research process was conducted in the following manner: Pregnant rats were first exposed to whole-body radiation emitted from wireless frequencies using two common signal modulations, CDMA and GSM. After the pregnant rats gave birth, their children were split up by sex and exposed to radiation at three different levels. The end of the study found that male rats had a statistically significant higher rate of a particular type of brain tumor (glioma) and nerve tumors in the heart within the CDMA-exposed groups.
However, there were no differences in tumors in the GSM-exposed rats and no differences in female rats.
One problem with the study, as Ars Technica's Beth Mole points out, is the type of control rats in the study who were not exposed to any cellphone radiation. These control rats (known as Sprague Dawley rats) have a roughly 1-2 percent chance of developing brain or heart cancer anyway. But none of the control rats in this study had either type of cancer, and all died early. If just one of them had lived long enough to develop either cancer, it would eliminate the statistical significance of the cancer link in male rats.
So why has this study gotten so much attention in the media while others which look at similar phenomena do not? Publication bias and media bias both play a role, as Carroll notes: It's more likely that a new study will be published if a link between cellphone usage and cancer is found than if no such link is found. And positive, frightening results can garner media websites more clicks and reads, often disseminating fear about an issue far beyond its realistic implications.
Finally, we have directly observable evidence in our daily lives that cellphone usage is probably not quite as linked to cancer as this study suggests. More than 90 percent of Americans use a cellphone regularly, which means that we would absolutely see a large increase in cancer diagnoses if cellphone usage caused brain tumors in even a tiny percentage of users. But as Carroll notes, the incidences of brain cancer in the U.S. has been dropping since the 1980s, so other factors are clearly at play.
Ultimately, one study does not provide the definitive link between cellphone usage and increased cancer rates. Future studies will perhaps need to take a larger view in light of existing work on the issue.