A comprehensive review of the best available evidence, commissioned by the World Health Organization, has found that mobile phones are not linked to brain and head cancers.
Led by the Australian Radiation Protection and Nuclear Safety Agency (Arpansa), the systematic review examined more than 5,000 studies. The most scientifically sound studies were selected and the weak studies were excluded.
The final analysis included 63 observational studies in humans published between 1994 and 2022, making it “the most comprehensive review to date,” said the review’s lead author, Associate Professor Ken Karipidis.
“We concluded that the evidence does not show a link between mobile phones and brain tumors or other head and neck cancers.”
The review, published on Wednesday, focused on cancers of the central nervous system (including the brain, meninges, pituitary gland and ear), salivary gland tumors and brain tumors.
The study found that there was no general association between mobile phone use and cancer, no association with long-term use (when people use their mobile phone for 10 years or more), and no association with the extent to which they use their mobile phone (the number of calls made or the time spent on the phone).
“I’m pretty confident in our conclusion. And what makes us pretty confident is … even though mobile phone use has gone up dramatically, brain tumor rates have remained stable,” said Karipidis, assistant director of Arpansa’s health impact assessment.
Mobile phones, like all devices that use wireless technology, such as laptops, radio and TV broadcasts, and mobile phone masts, emit radio frequency electromagnetic radiation, also known as radio waves.
Karipidis, who is also vice-chair of the International Commission on Non-Ionizing Radiation Protection, says that when people hear the word radiation, they immediately think it has to do with nuclear radiation.
“And because we hold the mobile phone close to our head when we make a call, there is a lot of concern,” Karipidis said.
“Radiation is basically energy traveling from one point to another. There are many different types, for example ultraviolet radiation from the sun,” he said.
“In our daily environment we are constantly exposed to low-level radio waves.”
Although exposure from mobile phones is still low, it is much higher than exposure from other wireless technology sources. Karipidis says phones are used close to the head.
The link between cell phones and cancer emerged from early studies in which researchers examined differences between a group of people with brain tumors, and a separate group without cancer by asking both about their exposure history.
The results of this type of study design are often biased, because while the non-tumor group provides good information, the tumor group often overestimates exposure, Karipidis said.
Based on some of these early studies, which suggested a possible link to brain tumors from holding a mobile phone to the head for long periods of time, the WHO’s International Agency for Research on Cancer (IARC) has identified radio frequency fields such as those from mobile phones as a possible cancer risk.
Karipidis said that while many people were concerned about the IARC classification, “this classification does not mean that much”.
The IARC has different classifications of cancer riskwith substances that can be classified as a “clear” carcinogen (such as smoking), or as “probable” or “possible” carcinogens.
By designating electromagnetic radiofrequency fields as a possible carcinogen in 2011, the WHO put them on a par with hundreds of other substances with uncertain evidence of harm, such as aloe vera, pickled vegetables and dry cleaners.
However, at the time there were some prominent doctors, such as Australian neurosurgeon Charlie Teo publicly raise awareness of the IARC decision about cell phones and cancer.
Since that classification, Karipidis says, many more cohort studies have been published that do not rely on people’s memories of past exposure. In addition, in 2019, the WHO commissioned a number of systematic reviews to investigate the health effects of radio waves.
Karipidis said another WHO-commissioned systematic review looking at male fertility and radio waves found that there was no evidence of a link between telephones and a decrease in sperm count.
Another one WHO-commissioned systematic review examining women’s fertility did find an association in some scenarios, such as influencing birth weight, “but that association occurred when exposure to radio waves was well above the safety limit,” Karipidis said.
Tim Driscoll, a professor at the University of Sydney and chair of the Australian Cancer Council’s occupational and environmental cancers committee, said the systematic review’s methodology was strong and the researchers should be considered independent.
“I think people should be reassured by this research… but it’s worth remembering that the studies are not perfect, but the evidence is certainly that mobile phones can be considered safe in terms of concerns about increased cancer risk,” Driscoll said.
Karipidis and his colleagues are now working on the second part of the study, in which they will investigate cancers less commonly associated with mobile phones, including leukemia and non-Hodgkin lymphoma.
Karipidis said concerns about the link between cancer and cell phones should be addressed, but stressed the importance of continuing research as the technology continues to develop.