Repacholi: ''Interphone onderzoek geeft geen uitsluitsel in debat over kanker en mob. telefonie.
dinsdag, 08 december 2009 - Categorie: Berichten Internationaal
De Heer Repacholi was jarenlang hoofd van de afdeling EMV bij de WHO en initieerde het zgn. Interphone onderzoek. Later bleek hij geld aangenomen te hebben van de telecomindustrie en ontpopte hij zich als industrie-consultant. Onderstaand zijn voorschot op de publicatie van het Interphone onderzoek dat nog dit jaar verwacht wordt.
Bron: 2 dec. 2009
Auteur: Michael Repacholi
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Do cellphones cause cancer? That question is about to be revived with the publication of a long-awaited study called Interphone. Given the public health implications, we can expect it to get a lot of media attention. But you should treat what you read and hear with caution.
A decade ago, when the study was being set up, there were great expectations that it would produce a definitive answer. It is now clear that it cannot.
Interphone was coordinated by the International Agency for Research on Cancer and established on the recommendation of the IARC's parent body, the World Health Organization. It comprises 16 studies in 13 countries that sought to determine whether cellphone use is associated with tumours of the brain (glioma), meninges (meningioma), acoustic nerve (acoustic neuroma) or salivary glands.
Interphone compared cellphone use in 6420 people who had these cancers (2765 with glioma, 2425 with meningioma, 1121 with acoustic neuroma and 109 with salivary gland tumours) with that of 7658 people without cancer. The studies were designed to work out whether those with cancer had used their mobiles for longer or more intensively than the others.
What we know already
Although the final results are still under wraps, we have some idea what they could be because many of the national studies have been released with mostly negative results (Epidemiology, vol 20, p 639).
Also, the results from five national studies that account for over 60 per cent of the people who participated in Interphone studies have already been combined and published. This research shows no clear link between cellphone use and acoustic neuroma (British Journal of Cancer, vol 93, p 842), glioma (International Journal of Cancer, vol 120, p 1769) or meningioma (International Journal of Epidemiology, vol 37, p 1304), though it could not rule out a possible elevated risk of glioma or acoustic neuroma from using a phone for more than 10 years.
It is therefore likely that Interphone will give cellphones a clean bill of health except for the small possibility of a risk of glioma or acoustic neuroma from intensive and long-term use, which requires further study before reaching any such conclusion. Unfortunately, it is also likely that the media will report this possible risk without any caveats, such as it probably being due to the limitations of the study, of which there are many.
It is widely recognised that the design of Interphone was the best available at the time. Even so, it has major flaws that cast doubt on its ability to identify any cancer risk from cellphones.
Researchers gathered Interphone data by interviewing people about their cellphone habits, their exposure to other sources of radio-frequency (RF) radiation – which cellphones use to transmit calls – and other risks such as smoking. Participants were asked how often and how long they had used their phones in the past, whether they used them in urban or rural areas, whether they were mostly stationary or in motion when they used their phone, whether they used hands-free kits, which ear they used and how their mobile phone use changed over time. They were also shown photos of different phones to identify models they had used.
Can you recall how much you used your cellphone five or 10 years ago? Of course not, and that is Interphone's biggest flaw. Scientific studies on RF health risks are only as good as their ability to assess RF exposure. For Interphone, this is plagued by ''recall bias'' that can affect the accuracy and reliability of the results.
Recall bias is made more likely by the widespread dissemination of the hypothesis that Interphone was set up to test – that cellphone use causes cancer. There is evidence that people with tumours overestimate their past use of a phone, perhaps because they ''know'' that their tumour may have been caused by mobile phones (Journal of Exposure Science and Environmental Epidemiology, vol 19, p 369).
A similar bias is seen in subjects' recall of which side of the head they held their phone: those with tumours localised on one side tend to overestimate how much they used the phone on that side (Scandinavian Journal of Public Health, DOI: 10.1177/1403494809341096).
A different problem arises from the fact that members of the control group were more likely than the population at large to be cellphone users. This is perhaps because the control group was selected at random, by invitation, and people without mobiles did not see the relevance of taking part. This ''selection bias'' could lead to an approximately 10 per cent underestimate of any possible risk (Annals of Epidemiology, vol 19, p 33).
On top of that, mobile phone technology changed significantly over the course of the study. These changes, such as switching from analogue to digital, have mostly reduced RF exposure. Phone use patterns have also changed, with increased texting and use of speakers and hands-free kits, further reducing RF exposure. In addition, different people hold their phone at different angles to their head and at different distances from their head while talking. This can also result in a huge variation in RF exposure that could not adequately be taken into account in the Interphone study.
RF in the clear
Interphone's results must be seen in the light of what is already known about the effects of RF on cells. The vast majority of laboratory studies, when considered collectively, find no relationship between RF field exposure and any form of cancer. All rigorous reviews of all the scientific literature have concluded that exposure to RF fields is not associated with an increased risk of cancer.
Nor has any mechanism been found by which RF exposure from mobile phones could cause cancer. RF fields do not have enough energy to break chemical bonds in DNA, so they simply cannot cause the mutations required to initiate cancer. Further, from a theoretical analysis of all possible ways that RF fields could act on cells and tissues, it does not seem possible for RF exposures at levels below the international limits to cause adverse health consequences.
Interphone should realistically be considered as a detailed preliminary study that has identified key methodological limitations which preclude the detection of any small risk of brain cancer due to cellphone use, if any exists. It has also shown that these limitations need to be addressed in subsequent studies: for example, tracking actual phone use in a group of people over many years.
Such studies will be needed to get to the bottom of the matter. Some are under way, but they take time. In the meantime public health policy should remain as recommended by the WHO. Over 50 countries have already adopted international standards that limit RF exposure from cellphones. As far as we can be reasonably sure, these guidelines are more than sufficient to protect us.
Further reading: Reliable information on the health effects of RF can be found on the WHO website
Michael Repacholi is a visiting professor of electronic engineering at the Sapienza University of Rome, Italy. He coordinated the International EMF Project at the World Health Organization for 11 years and was at WHO when the Interphone project was proposed and commenced. He was founding chairman and is chairman emeritus of the International Commission on Non-Ionizing Radiation Protection
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