No link between cell phone use and brain tumors, long-term Oxford study finds
A new study from the International Agency for Research on Cancer and the University of Oxford is reporting on an ongoing project that has been tracking the health of nearly one million women in the UK for more than 20 years. The findings indicate there is no association between increased risk of brain tumors and cell phone use.
For several decades there has been an ongoing debate around the safety of cell phones. Particular attention has been directed at the potential for cell phones to increase risk of brain cancer. After all, humans have never before placed these kinds of radiofrequency radiation-emitting devices so close to our brains.
An influential study in 2018, from the US government's National Toxicology Program (NTP), did find some evidence to suggest cell phone radiation can cause cancer in animals. However, those findings were controversial with many experts claiming experiments that subject rats to high doses of radiation for extended periods of time are in no way analogous to the kinds of real-world exposures humans get from using cell phones.
So it may be hypothetically possible for radiation from cell phones to cause brain tumors, but is it actually happening in the real world? To answer this question researchers have turned to large troves of epidemiological data to determine whether there are increasing rates of brain tumors in the general population.
In 2013 a team of researchers from the University of Oxford published a study looking at correlations between cell phone use and brain tumors in 791,000 women. The data came from a massive ongoing project called the Million Women Study.
The Million Women Study kicked off in the mid-1990s. By 2001 it had recruited one in four of all women in the UK born between 1935 and 1950. All participants are sent questionnaires every three to five years to gather data on lifestyle practices and general health.
The 2013 Oxford study looked at self-reported cell phone use and found no association with incidences of glioma, meningioma or non-central nervous system cancers. This new study, published in the Journal of the National Cancer Institute, offers a follow-up to the prior findings tracking 776,000 women for an average of around 14 years.
Over the follow-up period the researchers saw 3,268 women in the study develop a brain tumor. However, there was no link found between cell phone use and rates of brain tumors. There was also no link to be found between daily cell phone use and increased incidences of glioma, acoustic neuroma, meningioma, pituitary tumours or eye tumours.
Drilling down into the data the researchers also saw no difference in the rates of tumors appearing on the right side of the head versus the left side of the head in daily cell phone users. As prior studies have indicated the majority of cell phone use occurs on the right side of the head, this finding affirms the lack of evidence directly linking cell phone radiation with brain tumors.
The researchers are cautious to point out the limitations in their findings. The study did not include children or young people, although other studies have found no link between brain tumors and cell phone use in young cohorts. And, less than one in five women in the study reported using a cell phone for more than 30 minutes every week meaning it is unclear whether heavy cell phone use increases risk of tumors.
The researchers do address several outlying observational studies from recent years that have claimed to find associations between cell phone use and increased rates of brain tumors. According to the researchers, there has been no sign of increasing rates of brain tumors in general populations over recent times, so the few studies that have detected associations must have some kind of underlying bias in recruitment.
“In a series of case-control studies in Sweden, consistently strong positive associations for ever cellular telephone use were observed, even within a short time after first use,” the researchers noted in the study. “If true, this would by now have led to a massive epidemic of brain tumors that – fortunately – has not happened. Hence, some major underlying bias in either the recruitment of study participants or in assessing exposure is the likely explanation for their findings.”
Joachim Schüz, lead investigator on the new study, said the lack of frequent cell phone users in the dataset means heavy users should ideally still exercise caution and utilize hands-free options where they can. Addressing the difference between newer and older cell phones Schüz also pointed out modern smartphones tend to emit less radiation than earlier generations.
“Mobile technologies are improving all the time, so that the more recent generations emit substantially lower output power,” Schüz said. “Nevertheless, given the lack of evidence for heavy users, advising mobile phone users to reduce unnecessary exposures remains a good precautionary approach.”
The new study was published in the Journal of the National Cancer Institute.
Source: University of Oxford