Using 3G (third-generation) phones may put you at a higher risk of developing glioma, a type of brain or spine tumour, according to a recent study.
But medical experts The New Paper spoke to said there is no need to panic.
Said neurosurgeon Dr Keith Goh: "The public should not be alarmed, but should note that excessive use of mobile phones does carry some risks. As in all things, too much of something can be harmful."
The study, which was published last month in medical journal Pathophysiology, also found that those who have used mobile phones for more than 25 years have a tripled risk of developing glioma.
It was conducted by Swedish professor and oncologist Lennart Hardell and statistician Michael Carlberg. Both are from the oncology department at Orebro University Hospital.
The pair studied brain tumour patients diagnosed in Sweden between 1997 and 2003, and between 2007 and 2009.
It is the latest addition to the decade-long debate on whether mobile phones are harmful to the human brain.
In 2011, the World Health Organisation classified mobile phone radiation as possibly carcinogenic, alongside agents like crude oil and coal dust.
This means there is limited evidence of whether the radiation causes cancer in humans.
3G phones put a person at a higher risk of developing glioma compared to a 2G phone, as 3G transmission requires more energy, said Dr Wong Seng Weng, explaining the study findings.
This means those using 3G phones are exposed to more radiation, the oncologist said.
According to a global study released by Google last month, Singapore has the highest smartphone penetration, at 85 per cent.
Smartphones, which allows one to access the Internet fully, are typically 3G or 4G phones.
Scientists are reluctant to draw a direct causal link between mobile phone use and gliomas because of the type of radiation mobile phones emit, said Dr Wong, who heads The Cancer Centre, a Singapore Medical Group clinic.
"There is a reason people panic when you talk about the radiation in Fukushima. That is ionising radiation, high frequency, high radiation, and damages the DNA of cells, causing them to transform," he said.
"The radiation emitted from mobile phones is non-ionising, and much less likely to damage the DNA."
The study could also contain recall bias - an error caused by differences in the accuracy of the study participants' recollections.
"It is difficult to recall something as long as 25 years ago clearly," he added.
Brain tumour patients who are struggling to find the reason for their diagnosis are also likely to jump at phone radiation as a reason.
"They are likely to report high usage (of their phones) because in their minds, that will explain why they have brain tumours," the oncologist said.
But given that the cause of brain tumours is unknown, the study should not be simply dismissed, said neurosurgeon Dr Ivan Ng.
"We are a little bit into the unknown. It's premature to say there is no truth in the study at all. The link between cigarettes and lung cancer was drawn in the 1950s, but it was only in the 80s and 90s that people realised that."
"Similarly, brain tumour is something that takes many years to kick in. (The link) would probably be clearer in the future," he said.
Dr Wong warned against getting paranoid over the study, but at the same time, not to "throw caution to the wind".
"Some people have started using earphones, both wired or wireless. That's reasonable," he said.
He added: "You should probably avoid leaving your mobile phone by your pillow to be exposed to unnecessary radiation."
This article was first published on Nov 24, 2014. Get The New Paper for more stories.