Do Cell Phones Cause Cancer?

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Questions and fears about the potential role of cell phones as a cause of cancer have circulated widely over the past few decades. Many are confused, as they hear one report suggesting they cause brain cancer, followed by another saying there is no risk, followed by yet another demonstrating cancer in animals. So where does the real answer lie on this spectrum?

As with many exposures in our environment today, the jury is still out in many ways. So, while we learn more, it's worth exploring a few ways in which you can minimize your own risk.

black woman holding cell phone by water

Maria Korneeva / Getty Images

Cell Phones and Brain Tumors

Much of the human research looking at cell phones and cancer risk has concentrated on brain tumors, with mixed results. These include:

There have been a number of studies done at this time.

An Interphone study that took place over several years in several countries concluded that there is a statistically significant correlation between tumor location and side of cell phone use.

A different series of studies done by the International Agency for Research on Cancer also looked at cell phone use and the incidence of brain tumors. They again found an association between the risk of gliomas (ipsilateral, or on the same side of the head as phone use), acoustic neuromas, and heavy cell phone use.

A review in 2017 broke down evidence from the studies above (including animal studies) into nine different categories (Bradford Hill viewpoints) that can be used to evaluate whether exposure is linked with cancer (in this case, glioma). These included:

  • Strength: Meta-analysis showed increased risk with the highest exposure.
  • Consistency: The risk increased with a longer duration of use (latency).
  • Specificity: Increased risk was in the temporal lobe (the area of the brain nearest the ear).
  • Temporality: The highest risk was in the group who had used cell phones for 20 or more years.
  • Biological gradient: Cumulative use increased risk.
  • Plausibility: Animal studies showed an increased risk in rats. Radio frequency radiation (RFR) causes an increase in reactive oxygen species (ROS).
  • Coherence: There is a change (increase) in the incidence of glioma in at least some regions.
  • Experiment: Antioxidants reduced production of reactive oxygen species from RFR.
  • Analogy: An increased risk of glioma has been seen in people exposed to very low-frequency electromagnetic fields.

The conclusion was that cell phone RFR should be regarded as a carcinogen that causes glioma.

Cell Phones and Thyroid Cancer

Since the incidence of thyroid cancer has been increasing in many parts of the world, scientists wondered if cell phones may be playing a role in that increase. The answer may be both yes and no depending on other risk factors for the disease.

In a study looking at trends in the Swedish Cancer Registry from 1970 to 2017, researchers noted a significant increase in the incidence of thyroid cancer. They felt this was a true increase (not overdiagnosis), as a similar increase was noted in both small cancers and large cancers.

Since the increase corresponded to cell phone use, the researchers postulated that RFR may be a causative factor in the rising incidence. It's important to note that correlation doesn't mean causation. There could be other reasons for an increase in thyroid cancer incidence over this time period, so looking at the question from other angles is needed.

A 2019 study found no significant association between cell phone use and thyroid cancer, though there was a non-statistically significant increase in the incidence of thyroid microcarcinomas (tumors that were less than one centimeter in diameter) in people who had either used a cell phone for over 15 years, used their phone for more than two hours daily, or had the most cumulative use hours.

Cell Phones and Breast Cancer

A very small study evaluating the risk of breast cancer related to carrying a cell phone in a woman's bra was too small to draw conclusions, but more recent studies, including exposure to cell phone light at night, deserve more evaluation.

A very small case report in 2013 raised some possible concerns about breast cancer due to RFR. Four women between the ages of 21 to 39 were found to have multifocal (several tumors) invasive breast cancer, with the tumors concentrated in the area directly beneath where they carried their cell phones in their bras. Exposure was up to 10 hours daily and for several years. None of the women had any risk factors for breast cancer including negative family history and no genetic mutations (BRCA1/BRCA2) that would raise risk.

Breast cancer is one of the most common cancers in women and can clearly occur at a young age. What was striking to the research was both the similarity in tumor characteristics between the women (nearly identical morphology) as well as the clustering of tumors in the region directly below where the cell phone was carried.

A case report of only four women can't tell us much as to potential risk in the general population, but it did alert researchers that little data was available as to the safety of prolonged direct contact.

A 2019 study in Taiwan looked at heavy cell phone use ("cell phone addiction") and breast cancer risk.

In Taiwan, the incidence of breast cancer has increased over the past few decades, becoming the most common female cancer in that country in 2003.

Researchers looked at a group of women in Taiwan and compared those with heavy cell phone use to those who used their phones much less frequently. Those who were classified as having a "smartphone addiction" were 43% more likely to develop breast cancer. This risk increased substantially when women routinely used their cell phones for at least 4.5 minutes before bedtime (those who did so had a 5.27-fold increased risk over those who did not use their cell phone before bedtime).

A closer distance between the cell phone and their breasts was also correlated with risk. Closer distance (10 centimeters or less vs. over 35 centimeters) increased risk 59% overall.

The author's conclusion was that excessive smartphone use significantly increased the risk of breast cancer, especially among those with smartphone addiction, those who kept their cell phones close to their breasts, and those who had the habit of routinely using a cell phone before going to sleep. Certainly, this study needs to be repeated and studied in other countries as well.

Other Cancer Types and Cell Phone Risk

Studies have looked at the potential role of cell phone use on a few other cancers, with results either reassuring (no relationship) or equivocal at this time. These include:

Salivary Gland (Parotid) Tumors

Salivary gland tumors such as those of the parotid gland are uncommon, but an increased risk associated with cell phone use has been suggested.

A systematic review and analysis of 37 studies found that cell phone use was associated with a mildly increased risk of salivary gland tumors (28% more common). Since there are relatively few studies, however, it's not known whether there is a true relationship at this time.

Testicular Cancer

While social media abounds with recommendations that men not carry their cell phones in their pants pockets, there is little evidence that doing so could increase testicular cancer risk, at least at this time.

The risk of testicular cancer (seminoma and non-seminoma) has increased in developed countries over the last few decades, prompting researchers to look at a potential association.

A 2012 study compared the incidence of testicular cancer via the National Cancer Institute database with that of cell phone subscription data from the World Health Organization (WHO) looking at the period from 1991 to 2008. Changes in the incidence of testicular cancer were minor with respect to the increase in cell phone subscriptions. Based on the data, the researchers concluded there was "no convincing evidence" of testicular cancer risk associated with cell phone use. Certainly, as the latency period (time from exposure to cancer) of some cancers is prolonged, continued monitoring is needed.

Tips for People Who Are Concerned About Cell Phones

For those who remain concerned about cell phones and cancer, there are a number of things you can do to reduce your risk. These include:

  • Limiting the length of your phone calls
  • Using a landline if one is available
  • Using speaker mode or hands-free options such as Bluetooth
  • Texting instead of calling (but not if you are driving)
  • Avoiding cell phone use shortly before bed or keeping your cell phone in bed with you

A Word From Verywell

Overall, while there are suggestions of an increased risk of brain tumors with heavy cell phone use, the effect is not dramatic as, say, the relationship between smoking and cancer. That said, with an estimated 5 billion people in possession of a cell phone in the world, even a small risk could add up to significant illness.

Further studies are definitely needed to confirm or refute what we've learned to date, but for those who are concerned today, there are a number of simple measures that can be used to lower exposure to RFR.

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