What effect does mobile phone radiation have on your parotid gland? That’s the topic of my video Do Cell Phones Cause Salivary Gland Tumors?.

A summary of studies found no acute effects of cell phone radiation, such as nausea, headaches, dizziness, and fatigue, but researchers only looked at the short-term effects of mobile phones without considering any of the data on potential long-term effects. Finding no acute effects, they recommended that future research efforts should concentrate on possible chronic effects. You may recall that I explored the studies on brain tumors in my video Does Cell Phone Radiation Cause Cancer? and looked at the effects on the auditory nerve in our ear in The Effects of Cell Phones and Bluetooth on Nerve Function. But, looking at our brain and our ear isn’t enough. What about our parotid glands, the big salivary glands right next to our ear? You can see a diagram at 0:39 in my video. About one in a thousand people develop salivary gland cancer in their lifetime. Does cell phone use increase the chances of parotid gland tumor development?

Researchers had about a hundred people drool into test tubes and found that “[o]ver an hour talking with a cell phone decreases total antioxidant capacity of saliva in comparison with talking less than twenty minutes.” So, considering the major protective role of antioxidants against DNA damage induced by free radicals, which can lead to cancer, this could be a potential route by which cell phone use increases salivary tumor risk. This was just an observational study, though. Perhaps those who spend more time on their phones tend to eat worse diets than those who talk less.

In a more convincing study, researchers found that saliva taken from the salivary gland on the side of the head where participants held their cell phone had higher levels of inflammatory markers compared to saliva taken from the same person on the non-phone side of their head. Now, this increase in inflammation isn’t necessarily from cell phone radiation; it may just be from the heat generated by the phone. Simply pressing anything warm against your face for an hour a day may not be good for your glands.

Do the increased oxidation and inflammation actually translate out into cytogenetic abnormalities—that is, cellular and chromosomal abnormalities—in your mouth? Those who use cell phones a lot do appear to have “an increased number of broken eggs in the tongue.” Eggs? That’s a rather playful description of a cytogenetic abnormality associated with cancer, which you can see at 2:19 in my video. Okay, but what we really care about is  cancer. “Does Cell Phone Use Increase the Chances of Parotid Gland Tumor Development?” is the title of the first systematic review ever published to evaluate this, and the researchers found that cell phone use does appear to be associated with increased risk.

This is a good time to explore absolute risk versus relative risk. If you were asked whether you’d be willing to take a daily pill to reduce your chances of dying from a heart attack by 50 percent, you might jump at it. But, if you’re so young and healthy that your risk of a fatal heart attack is only two in a thousand over the next 10 or 20 years, then taking those 5,000 or so pills may not be worth it to you. Fifty percent sounds great, but if you’re talking about a really rare event, then it’s less exciting. So, even if cell phones did increase risk by 28 percent, then a lifetime of cell phone use would only increase your risk of getting such a tumor from a 1 in 1,400 chance to about a 1 in 1,100 chance.

If you want to reduce your risk, though, both the heat and emissions from cell phones are largely local phenomena, so you can use a speakerphone or headset to reduce exposure. You can also text more and talk less. Until we know more, “the adoption of such precautions, particularly among young people, is advisable.” In fact, there is enough concern that a researcher recommends young children to consider minimizing their use of cell phones altogether.