There has been no substantial change in the number of adult brain tumours since
mobile phone usage sharply increased in the mid-1990s, Danish scientists say.
The Danish Cancer Society looked at the rates of brain tumours among 20 to 79
year olds from Denmark, Finland, Norway and Sweden.
They found that trends in cancer rates had not altered from the period before
mobiles were introduced.
But they say longer follow-up studies are needed.
The research, published in the Journal of the National Cancer Institute, says
radio frequency electromagnetic fields emitted from mobile phones have been
proposed as a risk factor for brain tumours, but a biological mechanism that
could explain the potential effects has not been identified.
Cancer incidence
The study was based on 59,684 brain tumour cases diagnosed over 30 years from
1974 to 2003 among 16 million adults.
B rain tumours often take a very long time to develop so we will need to look
for any future changes in incidence rates to see if mobile phones could pose
any longer-term risks
Dr Alison Ross, Cancer Research UK
During this time, the incidence rate of cancers known as gliomas increased
gradually by 0.5% per year among men and by 0.2% per year among women.
For cancers known as meningioma, the incidence rate increased by 0.8% among men
and, after the early 1990's, by 3.8% among women.
This more rapid change for women was driven, the researchers say, by the 60-79
year age group.
Isabelle Deltour, of the Danish Cancer Society in Copenhagen who led the study
said the lack of a detectable increase in tumour rates up to 2003 may suggest
that the time it takes for cancer to develop from mobile phone use is longer
than 10 years of exposure or that the number of tumours it promotes is too
small to be detected.
She said: "Our results extend those of previous studies of time trends up to
1998 by adding five years of follow-up.
"Because of the high prevalence of mobile phone exposure in this population and
worldwide, longer follow-up of time trends in brain tumour incidence is
warranted."
Further research
Dr Alison Ross, Cancer Research UK's senior science information officer, agreed
that further research was needed: "Overall, the scientific evidence tells us
that using mobile phones for less than 10 years does not increase the risk of
cancer and this large study supports that conclusion.
"However, brain tumours often take a very long time to develop so we will need
to look for any future changes in incidence rates to see if mobile phones could
pose any longer-term risks."
Mike Dolan, of the Mobile Operators Association which represents all five UK
network operators said: "This finding is consistent with previous studies in
this field and will form part of the overall body of scientific research.
"The UK mobile phone operators are supporting a large cohort study which is a
recommendation of this paper."