Do Mobile Phones Cause Cancer? Science Continues to Challenge Assumptions

Findings from an important study investigating whether there is a link between mobile phone use and cancer risk have been published, with the conclusion that mobile phones may not increase cancer risk in humans, "contrary to popular belief" . It has not been difficult for those arguing otherwise to find appealing arguments. The fact that these results are preliminary findings, based on animal experiments, or that studies claiming the opposite exist does not appear to have prevented or discouraged many people from claiming that mobile phones cause cancer. Fortunately, clearer data are now available on the relationship between mobile phones / smartphones and cancer.

Mobile phones emit non-ionizing radiation measured as radiofrequency (RF) energy. While exposure to high doses of ionizing radiation is known to cause cancer through DNA damage, whether prolonged exposure to non-ionizing radiation causes cancer is unknown.

The most comprehensive study on this subject to date, conducted by the United States National Toxicology Program (NTP) with a budget of 25 million dollars, published its results in February 2018, announcing that the cancer risk of mice exposed to high levels of mobile phone waves did not increase. Interestingly, mice exposed to mobile phone radiofrequency waves were even found to live longer.

United States National Toxicology Program study design

The United States National Toxicology Program study is a major undertaking, with current reports for rats and mice exceeding 650 pages. Early results were announced in 2016. Before discussing the new full results, let us examine the research itself. Briefly, this was an animal study with no human subjects. Rats and mice were studied, with these animals exposed to mobile phone radiofrequency radiation every day for 9 years, starting in the womb before birth. The level and duration of mobile phone wave exposure in the rodents were much greater than even those of people most heavily exposed to mobile phones.

The aim of the United States National Toxicology Program was not to determine whether human mobile phone use was dangerous, but to test toxicity. This is, in fact, a distinction between hazard and risk. Even if we generalized the results of this study to humans, the findings would not be directly related to how a person uses a mobile phone.

Malignant gliomas (brain tumors)

The brain is the organ most exposed to mobile phone waves, so the greatest question is whether mobile phones increase the risk of brain tumors .

One of the most important findings was that no clear association was shown between brain tumors and mobile phone use in rodents. The inconsistency between these results and the early study results reported in 2016 was attributed to differences in statistical analyses.

Some studies suggest that talking with a mobile phone held to the ear may increase the risk of a tumor called acoustic neuroma . However, other studies subsequently rejected this approach. In this study, an associated relationship appeared only in male rats. It did not occur in female rats, male mice or female mice.

Cardiac schwannomas

Schwannomas are tumors arising from nerve sheaths and are rarely detected in the heart. In the United States NTP study, the rodents' entire bodies, rather than only their brains, were exposed to high doses of mobile phone radiofrequency waves. The cardiac schwannoma analysis found schwannomas not only in the heart, but also in other organs such as the pituitary gland, trigeminal nerve, salivary gland and eye. However, there was no significant difference in schwannoma rates between experimental and control rats. Therefore, this analysis was not considered very meaningful either.

Conclusion

Since the late 1990s, when mobile phones began to be widely used worldwide, almost 20 years have passed. During this period, population observational (epidemiological) studies have not provided convincing evidence of an increase in brain tumors in humans. However, longer observation is needed before stating definitively that mobile phones do not increase brain tumor risk in humans.

The graph above shows annual numbers of new cases and deaths from brain and other nervous system cancers in the United States. One argument supporting the view that mobile phones do not increase cancer risk is that — although mobile phones have been in our lives for only 20 years — no increase in brain tumor incidence has yet been observed in humans; in fact, a slight decrease in brain tumor incidence is being observed in the United States.