Wednesday November 9 2011
Mobile phones have potential risks in the long-term
“Mobile phones could be a 'health time bomb', say experts who are urging ministers to warn the public,” the Daily Mail reported. The newspaper said that a leading group of scientists have published a report looking at research into the health risks of using mobiles, in which they state that “the government is underplaying the potentially 'enormous' health risks – especially for children, whose smaller, thinner skulls are more susceptible to radiation”.
This news report is based on a report by MobileWise, a UK charity aimed at raising awareness of mobile phone health issues. The report includes a narrative review of evidence into the risks of mobile phones to date. However, this review was not systematic and therefore may not show the complete picture. Furthermore, the researchers themselves acknowledge that the studies cited have limitations, the risks are still uncertain and no conclusions have been drawn.
Mobile phones are a relatively new exposure, and there has been and continues to be a lot of research into whether they present a risk. The balance of evidence that exists so far points to them not being a risk, but potential risks over the long-term have not yet been disproved.
As reported in July this year, current UK government advice for children and young people under 16 is to use mobile phones only for essential purposes and to keep calls short. The World Health Organization (WHO) has also taken a precautionary approach, and recently classified mobile phones as a “possible carcinogen”, putting them into the same risk bracket as traffic fumes and coffee. The classification means that the link is far from certain, and WHO states there is only “limited evidence” of a link, and that the results supporting a link may be due to other factors that have distorted study data.
Where did the report come from?
The news story is based on a report by MobileWise, a UK charity aimed at “raising awareness of mobile phone health issues, and promoting action to protect public health”.
Several scientific advisers, specialising in disciplines ranging from neurosurgery to environmental science, helped to produce this report. The report reviews scientific papers that have indicated health risks associated with mobile phones and assesses their methodological quality. However, this review was not systematic (in other words, it did not carry out a careful search for all studies that have investigated mobile phone risk, and so may not have included all relevant research; either those that have associated mobile phones with health risks and those that have not).
A systematic review would allow an overall assessment to be carried out of the evidence for any health risks. Narrative reviews such as this one can highlight interesting examples from one side of an argument, but cannot provide overall conclusions. A potential downside of a narrative review is that the authors can select (unwittingly or not) studies that support their own opinions. Additionally, the references included in this review are not restricted to human studies, and animal and laboratory studies have only limited relevance to humans unless they have been followed up with human studies.
What did the report find?
The report looked at studies showing a risk from mobile phones in the following health areas:
- cancer and other tumours
- damage to fertility and reproduction
- DNA damage
- damage to other biological processes
- health of children and young people
The report assessed observational studies in humans and also used data from laboratory studies. The reviewers highlight some problems with how some of the observational studies were carried out. These include:
- Some of the studies asked people to recall their mobile phone usage, which may be difficult to remember.
- In older studies, people’s phone use in the past may not reflect their current use.
- Studies that have assessed long-term exposures have done so for generally no more than 10 years, which may not be long enough to record health problems that occur later on in life.
The newspaper reports have particularly focussed on the health risks of mobile phones for children. The review said: “Laboratory studies have shown consistently that children’s heads absorb up to double the energy that a large adult does when making a mobile phone call and the energy can be concentrated in certain areas of the child’s brain, resulting in up to three times the absorption in these areas.” It added: “One study has found that the risk of brain cancer after prolonged mobile phone use is significantly greater in younger users.” However, the review did not give any explicit details of these studies.
In their conclusions on the health risks of mobile phones for children, the reviewers said that “large-scale epidemiological studies have not studied children, leading to major gaps in our understanding of the differences in the profile of risks for children and particularly for the developing brain,” and that a greater focus of research in this area is required.
What did the report conclude?
The reviewers said: “The substantial body of evidence highlighted in this report suggests that mobile phone use may be linked with a range of important health problems. These include, but are not limited to, brain tumours and the evidence has serious implications for public health. Although further research is needed, it makes sense to err on the side of caution in the meantime.”
It should be noted that there were limitations to this report; it was not a systematic review and appraisal of and links to the evidence were not always clearly stated in the document. Although some assessment was made of the methodological quality of the studies, the reviewers did not restrict their analysis to higher quality studies only. The reviewers are correct that further research is needed and that this is an important area of research, but a useful first step would be to conduct a systematic review to describe the full extent and quality of the evidence to date in order to prioritise areas for future research.
What is the official guidance on mobile phone safety?
More health information on mobile phones can be found on the HPA website.
The NHS Choices Health AZ page on mobile phone safety
WHO: Electromagnetic fields and public health: mobile phones