Cell Phones

Cell phones cause brain tumors

Let’s start with some facts. Cell phones are hugely popular. Worldwide estimates put their usage at more than three billion people. In the United States, more than 270 million people use cell phones, including about half of children age eight to twelve. We also know that exposure to radiation increases your risk of developing cancer (see the section on cancer). And cell phones do emit radiation. So it shouldn’t come as a surprise that there is an ongoing debate as to whether this widespread use of a device that emits radiation causes cancer—specifically brain tumors.

Many studies have been published in this area. The vast majority of them are what we call case-control studies: First, you gather a group of people with brain tumors. Then, you gather a group of people without brain tumors. Then you ask them about their day-to-day activities (such as the frequency of cell phone use) to see if there are differences between the two groups.

While this type of study can sometimes give us good information, it’s important to recognize that case-control studies are among the weaker types of scientific studies. Unlike randomized controlled trials, a case-control study will not prove that cell phones do or do not cause brain tumors. And, unlike in prospective cohort studies, which follow a group of people forward in time through the study, there is a real problem with recall bias. Recall bias happens when someone with a particular issue or disease (in this case, a brain tumor) is more likely to recall activities that might have caused their issue or disease than someone who does not. The danger with case-control studies is that people with brain tumors may have heard the theory that cell phones cause brain tumors, and therefore may be more apt to recall their cell phone use than people without brain tumors.

There are so many of these studies about cell phones that we won’t try to summarize them all. Luckily, that has already been done for us! In 2008, a scientist summarized data from thirty-three studies in the peer-reviewed scientific literature. This summary found major flaws in the research that make it difficult to draw solid conclusions from all of these studies.

Another group attempted a meta-analysis of the literature. They felt that twenty-three studies were good enough to be included in the analysis. All of them were case-control studies. They found overall that, compared to rarely or never using a cell phone, regularly using a cell phone did not cause malignant or benign brain tumors.

The studies point out some important issues contradicting the idea that cell phone use is connected to brain tumors: With so many people using cell phones, you could expect, if there was a major association between cell phones and brain tumors, the number of tumors would be through the roof. Three billion people use cell phones! Even if there is an association, it has to be very small. Moreover, the types of brain tumors that have been more common recently take decades to appear. Cell phones, on the other hand, are a relatively new invention. We know from previous work that there is usually a long time period between exposure to radiation and the development of slow-growing brain tumors. According to that timeline, even if there were a link, we shouldn’t see a jump in brain tumors caused by cell phones until the 2030s.

Let’s remember something else too: there are much greater risks to our lives than cell phones. That’s for sure. After all, the number one killer of children in the U.S. is car accidents, and yet how many people out there think cars should be banned? As a society, we accept that the quality of life derived from driving is greater than the risks having people die in car accidents. If you disagree, don’t drive. Almost no one does that. The risk of brain tumors is so low that, even if it exists, few would likely forgo their cell phone to reduce it.

Furthermore, although we talk about an increase in brain tumors, there has been no explosion of brain tumors recently in the population. A study published in the Journal of the National Cancer Institute in 2009 examined data for cancers in four countries with registries from 1974 to 2003. Over that time, almost 60,000 people in a population of 16 million adults between ten and seventy-nine years were diagnosed with brain tumors. While a slow increase in rates of gliomas and meningiomas (faster-growing tumors) was seen throughout the same time period, no changes in incidence were seen from 1998 to 2003, five years when cell phone use increased dramatically and when you would expect to see more brain tumors because of that increase.

Case-control studies are a reasonable measure for determining a link between the activities we undertake and the diseases we develop. But cell phones are so widely used that, honestly, if they were so dangerous, we’d be seeing that effect right now. That’s just not happening. Additional studies will be needed to see if they cause long-term harm, but as of now, this is a myth.