Despite the weight of scientific research finding no causal or significant connection between mobile phone usage and cancer, fears about possible radio-frequency exposure and health-related outcomes are still common.
There are two reasons why users may be concerned that phone usage is linked to certain types of cancers. Firstly, it is known that phones emit low-level radiofrequency electromagnetic fields when sending and receiving signals. Secondly, phone use is widespread and frequent, with phones often directly held against the head during use. These associations have led some to be concerned that even a minimal absorption of radiation by the brain could have potential effects on health. Public opinion had the same worries when microwaves were first brought into common use. However, both use a safe type of nonionising radiation.
Over the last couple of decades, researchers have frequently put the use of mobile phones to the test to determine if these fears are based on any level of truth. Scientists, however, have been split about the potential biological effects for a variety of reasons. One issue is the source of funding. Research in 2006 questioned the interpretation of results based on the sponsorships financing the research. Still, most studies have withstood examination, with conclusions that there is nothing to worry about.
And yet, the understanding of the risk by the lay person has not been helped by conflicting results. Most notably, in 2011, the International Agency for Research into Cancer (IARC), a part of the World Health Organisation (WHO), classified mobile phone radiation as a “possible” human carcinogen. While this meant that there was some evidence linking mobile phones to cancer, it was too weak to make any strong conclusions. However, it was enough to cause public concern and continue to fuel misinformation. These concerns were also in spite of the results of a large Danish cohort study released just a few months later which answered some of the outstanding questions from the previous report and suggested there was little evidence for a causal association.
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There are several reasons why research in this area has been deemed inconclusive. Recall bias and inaccurate reporting can affect results when study participants are questioned about habits before and after a diagnosis. Insufficient participant controls in studies are also a factor, as healthy people are not as likely to enrol in studies compared to those diagnosed with brain tumours. Furthermore, assessing exposure, insufficient follow-up of exposed participants, and changing technology and improvements in devices alter results due to the differing radio frequencies of analogue and digital devices. All of this contributes to the varying results of studies and their limitations. However, over a decade later with continuous research, there remains a conclusive argument across the board that further research is needed.
The epidemiological review by IARC in 2011 classified radio waves as a possible carcinogen through evidence from human observational studies. Despite this method being one of the best tools scientists have to investigate long-term health effects, the evidence was limited, with potential for bias. The results of this report indicated that “the evidence, while still accumulating, is strong enough to support a conclusion and the 2B classification. The conclusion means that there could be some risk, and therefore we need to keep a close watch for a link between cell phones and cancer risk.”
In September 2024, a new systematic review was published. The analysis was commissioned by WHO and is based on a much larger data set of human observational studies than its 2011 counterpart. This major report includes more than 60 comprehensive studies published between 1994 and 2022 and has found no link between mobile phones or wireless devices and cancer. In comparison to the IARC assessment of the epidemiological studies, this new systematic review was based on stricter inclusion criteria. Researchers took into account bias using a three-tiered system to evaluate inaccurate reporting and also noted the varying elements for exposure risk.
Prof Deirdre Murray, director of the National Cancer Registry has welcomed this new report, saying it “provides the best evidence to date that using mobile phones does not cause brain cancer. It also provides further reassurance that time spent on the phone or number of years using a mobile phone does not increase cancer. The findings of this report are consistent with what we have experienced in Ireland. Irish use of mobile phones has soared since 1994, but NCRI data shows that brain cancer incidence rates have remained stable.”
Based on the research analysis, there is no association between long-term use of a phone (10 years or more) and brain cancer incidence, and no link between the amount of use and brain cancer (how long a person spends on their phone) was found. Considering, the billions of people who use mobile phones daily, the researchers determined that if there was a significant connection, rates of cancer diagnosis in the brain and neck would have increased. Using simulation studies, the researchers modelled what potential rates would look like if there were any causal effects. Due to this substantive review and other studies that have challenged the risks, IARC will likely re-evaluate the classification of mobile phones as a “possible carcinogen”.
Of course, mobile phones have other associated risks to be cautious of – for example, being distracted by a phone while driving, and the neurological effect on a person’s memory, learning, and cognitive function.
But for now, we can at least be comforted by what the science says. Mobile phones do not cause cancer.
