Mobile phones are not linked to brain and head cancers, a comprehensive review of the highest quality evidence available commissioned by the World Health Organization has found. Led by the Australian Radiation Protection and Nuclear Safety Agency (Arpansa), the systematic review examined more than 5,000 studies from which the most scientifically rigorous were identified and 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”, the review lead author, associate prof Ken Karipidis, said. “We concluded the evidence does not show a link between mobile phones and brain cancer or other head and neck cancers.” Published on Wednesday, the review focused on cancers of the central nervous system (including brain, meninges, pituitary gland and ear), salivary gland tumours and brain tumours. The review found no overall association between mobile phone use and cancer, no association with prolonged use (if people use their mobile phones for 10 years or more), and no association with the amount of mobile phone use (the number of calls made or the time spent on the phone). “I’m quite confident with our conclusion. And what makes us quite confident is … even though mobile phone use has skyrocketed, brain tumour rates have remained stable,” said Karipidis, Arpansa’s health impact assessment assistant director. Mobile phones – like anything that uses wireless technology including laptops, radio and TV transmissions, and mobile phone towers – emit radio-frequency electromagnetic radiation, also known as radio waves. Karipidis, who is also the vice-chair of the International Commission on Non-Ionizing Radiation Protection, said people hear the word radiation and assume it is similar to nuclear radiation. “And because we use a mobile phone close to the head when we’re making calls, there is a lot of concern,” Karipidis said. “Radiation is basically energy that travels from one point to another. There are many different types, for example, ultraviolet radiation from the sun,” he said. “We’re always exposed to low-level radio waves in the everyday environment.” While exposure from mobile phones is still low, it is much higher than exposure from any other wireless technology sources since phones are used close to the head, Karipidis said. The association between mobile phones and cancer came about from early studies where researchers investigated differences between a group of people with brain tumours, and a separate group without the cancers by asking both about their exposure history. The results from this kind of study design tend to be biased because while the group without the tumour provide good information, the group with the tumour tend to overreport their exposure, Karipidis said. Based on some of these early studies showing there might be a possible association with brain cancer from mobile phone use against the head for many hours, WHO’s International Agency for Research on Cancer (IARC) designated radio-frequency fields like those from mobile phones as a possible cancer risk. Karipidis said although many members of the public became concerned due to the IARC classification, “this classification doesn’t mean all that much”. The IARC has different classifications of cancer risk, with substances able to be classified as a “definite” carcinogen (such as smoking), or as “probable” or “possible” carcinogens. By designating radio frequency electromagnetic fields as a possible carcinogen in 2011, the WHO put them on par with hundreds of other agents for which evidence of harm is uncertain, such as aloe vera, pickled vegetables, and working in a dry cleaners. However, at the time some high-profile doctors such as the Australian neurosurgeon Charlie Teo publicly raised the profile of the IARC’s decision around mobile phones and cancer. Since that classification Karipidis said many more cohort studies had been published which do not rely on people to recall their past exposure and in 2019 the WHO commissioned a number of systematic reviews to look at the health effects from radio waves. Karipidis said another WHO-commissioned systematic review which looked at male fertility and radio waves found that there was no evidence of an association between phones and a drop in sperm count. Another WHO-commissioned systematic review which looked at female fertility did find an association in some scenarios such as affecting birth weight, “however, that association occurred when exposure to radio waves was far 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 feel reassured by this study … but it’s worthwhile just remembering that the studies aren’t perfect, but the weight of evidence certainly is that mobile phones should be considered safe to use in terms of any concerns about increased risk of cancer,” Driscoll said. Karipidis and his colleagues are now working on the second part of the study, which will examine cancers less commonly associated with mobile phones, including leukaemia and non-Hodgkin lymphoma. Karipidis said the concerns around links between cancer and mobile phones should be put to rest, but emphasised as technology would continue to develop it was important to continue research.