Cellphones 'raise tumour risk'
2007-10-03 09:32
New York - Using a cellphone for more than a decade can double the risk of some types of brain tumours, Swedish researchers said on Tuesday.
Dr Lennart Hardell and scientists at the University Hospital in Orebro, Sweden said their analysis of previous studies shows "a consistent pattern of increased risk for acoustic neuroma and glioma".
Acoustic neuromas are benign growths on the nerve linking the ear to the brain, while gliomas are malignant, difficult-to-treat tumours of the brain and nervous system.
The researchers also found that the greatest risk of developing a tumour is on the side of the head where the cellphone was held.
Hardell and his team identified 18 studies of brain tumour risk among long-term cellphone users, 11 of which provided data for 10 years or longer.
When the findings were analysed collectively, the researchers found people who had used cellphones for at least a decade had a 2.4-fold greater risk of acoustic neuromas and were twice as likely to develop gliomas.
Scientists fear cellphones could boost brain tumour risk by exposing the brain to electromagnetic energy. But early studies did not have a long enough follow-up time to fully account for long-term risk, Hardell and his team reported in journal Occupational Environmental Medicine.
Enough time has now passed since cellphones were introduced to analyse risks of cellphone use for 10 years or longer, which they believe is a "reasonable minimum period" to estimate risk.
One study in the analysis found no increased tumour risk with cellphone use, but it did show that cellphone users who developed brain tumours had larger tumours than non-cellphone users.
They found the greatest risk was for tumours located in the area of the brain with the most exposure and the study periods allowed enough time for tumours to develop.
But the researchers added that longer follow-up is needed, because an increased risk for other types of brain tumours cannot be ruled out.