If you’re reading this, chances are good you own a cell phone. In fact, it’s probably in your pocket right now, or at least within easy reach. You might even be reading this article on your smart phone.
Twenty years ago, cell phones were still somewhat of a novelty, mildly cumbersome, and were most decidedly “dumb,” with screens just large enough to display a phone number. Now, 90 percent of American adults own a cell phone, and well over half have a smart phone. (1) The question is, what effect—if any—does this have on our health?
In this article, I’ll look at the two most well-researched health conditions associated with cell phone use: male infertility and brain cancer.
Can Cell Phones Cause Infertility?
Several epidemiological studies have found an association between cell phone use and male infertility and decreased sperm quality. For example, a study published in 2008 found that of 361 men attending an infertility clinic, participants who used a cell phone more frequently had lower sperm count, motility, and viability, and had more sperm with abnormal structure. (2) Two other studies also found a higher percentage of abnormal sperm in men who used a cell phone. (3, 4)
Animal experiments have also been conducted to better determine whether a cause-and-effect relationship exists, and what the mechanism might be. Studies where rodents were exposed to cell phone radiation have found decreased sperm motility and abnormal structure, as well as increased DNA damage and oxidative stress. (5) For example, rats exposed to an active cell phone for just one hour per day for four weeks exhibited reduced sperm motility and increased oxidative stress compared to controls who were exposed to a cell phone without batteries for the same period of time. (6)
Is your cell phone habit harming your health? #infertility #cancer
On the other hand, a different experiment found that young rats actually exhibited better sperm motility and structure following exposure to cell phone radiation, which is opposite of what other studies have found. (7) It’s also important to note that animal research doesn’t generalize to humans particularly well in this case. Due to differences in structure of the testes, the doses of radiation used likely have a much larger effect on the animals than it would on humans.
Researchers have also conducted experiments on human semen samples by exposing half of a given sample to cell phone radiation, and keeping the other half as a control. Exposed samples had higher levels of oxidation, as well as decreased sperm motility and viability. (8, 9)
Several thorough reviews and a couple meta-analyses have been conducted over the past decade to summarize the research on cell phones and reproductive health. (10, 11, 12, 13, 14, 15, 16) In general, the authors come to the same conclusion: that a significant amount of evidence does indicate that cell phone radiation could be harmful to male reproductive health, but that the study designs are inconsistent, often not reproducible, and don’t always adequately control for confounding variables. That said, there’s enough concerning preliminary evidence to warrant caution and further investigation.
Do Cell Phones Cause Brain Cancer?
Cancer is another topic that has garnered significant attention from the public with regards to cell phone safety. After all, when most people hear the word “radiation,” they probably think of DNA-zapping, cancer-causing ionizing radiation, like gamma rays or x-rays. So it’s important to keep in mind that microwave radiation—the frequency used by cell phones (and microwave ovens)—is non-ionizing, and is actually a lower frequency than UV rays or even visible light.
In-vitro and animal research reflects this—cell phone radiation was not found to cause or promote cancer in isolated human cells or in rodents. (17, 18, 19) But we still have to consider the other effects that cell phone radiation could have on the body, and whether those effects could increase the risk of cancer long-term.
For example, as I mentioned in the previous section, some evidence indicates that cell phone radiation increases oxidative stress in cells, which can lead to DNA damage. Several studies have found increased DNA damage in the brain cells of rats after exposure to cell phones, and since the effect was blocked by antioxidant administration, it’s likely that oxidative stress was the cause. (20) But many animal studies have also found no increase in DNA damage following exposure to cell phone radiation, so experimental evidence remains equivocal. (21)
One of the few human studies involving cell phone exposure found that when two cell phones, one active and one inactive, were placed on either side of a participant’s head for 50 minutes, glucose metabolism increased on the side of the brain exposed to the active phone. (22) This study got a lot of attention, but a subsequent study came up with opposite results, where glucose metabolism decreased on the side of the brain exposed to cell phone radiation. (23) Regardless, the clinical implications of these results (if any) are unknown.
Epidemiological evidence is also inconclusive. The WHO has classified cell phone radiation as “possibly carcinogenic to humans,” primarily based on a couple observational studies that found associations between cell phone use and brain cancer. (24) The first one, the Hardell study conducted in Sweden, was a case-control study that matched each “case” (a person with brain cancer) to a “control” (a person as similar as possible to the case, but without cancer).
They published their results in several papers, reporting an increased risk for brain cancer in people who used cell phones, particularly cancers occurring on the same side of the head that the phone was used on. (25, 26, 27, 28) Risk increased with increasing time spent on the phone, and was highest in people who started using a cell phone before age 20.
The second study—the INTERPHONE study—collected case-control data from 13 different countries, and in contrast to the Hardell study, found no association between cell phone use and brain cancer aside from a small association at the highest level of cell phone use. (29, 30) The authors (as well as two reviews published soon after) concluded that overall, the current data doesn’t support a causal association. (31, 32) But another long-term epidemiological study published later added more evidence supporting a connection, so the case is far from closed. (33)
So, Is My Cell Phone Harming My Health?
The bottom line is that we don’t know. As you’ve seen, there’s quite a bit of research on the safety of cell phones, but the results have been varied and inconclusive. Additionally, the biological mechanisms by which cell phone radiation could cause these adverse health effects are only just beginning to be understood, and until a clear mechanism exists, we can’t draw any conclusions from the epidemiological data we have.
That said, there’s enough concerning preliminary evidence to warrant caution. In a way, we’ve all unwittingly become part of an uncontrolled population-wide experiment on cell phone safety, and the precautionary principle applies: we don’t know that it’s harmful, but it makes sense to take reasonable measures to reduce exposure in case it is.
It’s also important to note that children absorb more cell phone radiation than adults do, because they have thinner skin and bones and a higher water content in their tissues. (34, 35) With that in mind, it’s probably best to limit your child’s exposure to wireless devices like cell phones. (Not to mention the potential adverse effects of too much screen time on children’s attention spans, focus, and cognitive development.)
So instead of holding your iPhone to your ear for that two-hour call, try plugging in ear buds so you can set your phone on the table next to you. If you’re a guy, get in the habit of carrying your phone in a backpack, or putting it in airplane mode while it’s in your pocket. And unless you’re expecting a call, perhaps consider leaving your phone in another room or in your bag. If nothing else, your concentration and connection to the real world will likely benefit from not having your blinking, buzzing cell phone as a constant companion.