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dinsdag, 29 juni 2010 - Categorie: Berichten Nederland
Oorspronkelijk geplaatst 24 juni 2010. Laatste update met toegevoegd commentaar uit België 29 juni 2010.
Berichten%20Internationaal/4443 (voor uitvoerig commentaar)
AMSTERDAM - Dichtbij een GSM-mast wonen verhoogt niet de kans op kanker bij kinderen. Dat blijkt uit een nieuw onderzoek van de Britse hogeschool Imperial College London.
Het onderzoek is gehouden onder 7.000 kinderen. Hieruit bleek dat degenen wiens moeders tijdens de zwangerschap dichtbij een GSM-mast woonden, geen verhoogde kans op kanker hadden ten opzichte van zij die ergens anders woonden.
De enorme stijging van mobiele telefoongebruik de laatste 20 jaar heeft onder consumenten en experts veel vragen opgeroepen over de kwaadaardigheid van de straling die de apparaten en bijbehorende masten afgeven.
Er zijn dan ook al talloze onderzoeken uitgevoerd, waarbij voornamelijk de nadruk op telefoongebruik is gelegd. Eerder dit jaar werd een groot, tien jaar durend onderzoek hiernaar afgerond, maar de onderzoekers konden geen harde conclusies trekken uit de resultaten.
Voor het originele bericht zie:
Medisch Contact publiceert iets genuanceerder:
Auteur: Sophie Broersen
Niet meer kinderkanker door gsm-masten
Blootstelling aan straling van gsm-masten tijdens de zwangerschap verhoogt het risico op vroege kanker bij het kind niet. Dat blijkt uit een case-control studie die BMJ publiceerde.
Paul Elliott c.s. analyseerden gegevens van 1397 kinderen die tussen hun eerste en vijfde levensjaar kanker hadden gekregen, en 5588 gematchte kinderen zonder kanker. De onderzoekers keken hoe groot de afstand was tussen de woonplaats van hun (zwangere) moeder en de dichtstbijzijnde gsm-mast.
Tussen de gezonde kinderen en de patiëntjes was geen significant verschil in de afstand tot masten, noch in de sterkte van de straling. Beide groepen waren qua sociaaldemografische factoren vergelijkbaar.
In een begeleidend commentaar wijst John Bithell erop dat de afstand tot een mast nog niet hetzelfde is als blootstelling aan straling: dat hangt ook af van andere factoren, zoals het type gebouw waarin kind en moeder wonen. Toch vindt ook Bithell dat artsen patiënten kunnen geruststellen als zij in de buurt van een gsm-mast wonen: er is geen bewijs voor een negatief effect. Dat is ook niet uit experimenten gebleken.
BMJ 2010, doi: 10.1136/bmj.c3077 en bmj.c3015
Het oorspronkelijke abstract in de Britisch Medical Journal:
Mobile phone base stations and early childhood cancers: case-control study
Paul Elliott, professor of epidemiology and public health medicine, head of department, director, MRC-HPA centre for environment and health, Mireille B Toledano, senior lecturer in epidemiology, J Bennett, research fellow, L Beale, research fellow, K de Hoogh, senior research officer, N Best, professor of statistics and epidemiology, D J Briggs, professor, chair in environmental and health sciences, school of public health
1 Small Area Health Statistics Unit, MRC-HPA Centre for Environment and Health, Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, St Mary’s Campus, London W2 1PG
Correspondence to: P Elliott email@example.com
Objective To investigate the risk of early childhood cancers associated with the mother’s exposure to radiofrequency from and proximity to macrocell mobile phone base stations (masts) during pregnancy.
Design Case-control study.
Setting Cancer registry and national birth register data in Great Britain.
Participants 1397 cases of cancer in children aged 0-4 from national cancer registry 1999-2001 and 5588 birth controls from national birth register, individually matched by sex and date of birth (four controls per case).
Main outcome measures Incidence of cancers of the brain and central nervous system, leukaemia, and non-Hodgkin’s lymphomas, and all cancers combined, adjusted for small area measures of education level, socioeconomic deprivation, population density, and population mixing.
Results Mean distance of registered address at birth from a macrocell base station, based on a national database of 76 890 base station antennas in 1996-2001, was similar for cases and controls (1107 (SD 1131) m v 1073 (SD 1130) m, P=0.31), as was total power output of base stations within 700 m of the address (2.89 (SD 5.9) kW v 3.00 (SD 6.0) kW, P=0.54) and modelled power density (–30.3 (SD 21.7) dBm v –29.7 (SD 21.5) dBm, P=0.41). For modelled power density at the address at birth, compared with the lowest exposure category the adjusted odds ratios were 1.01 (95% confidence interval 0.87 to 1.18) in the intermediate and 1.02 (0.88 to 1.20) in the highest exposure category for all cancers (P=0.79 for trend), 0.97 (0.69 to 1.37) and 0.76 (0.51 to 1.12), respectively, for brain and central nervous system cancers (P=0.33 for trend), and 1.16 (0.90 to 1.48) and 1.03 (0.79 to 1.34) for leukaemia and non-Hodgkin’s lymphoma (P=0.51 for trend).
Conclusions There is no association between risk of early childhood cancers and estimates of the mother’s exposure to mobile phone base stations during pregnancy.
Met direct daarop twee ''Letters to the Editor''(doesnot prove anything) van gerenommeerde wetenschappers:
Tot slot het vernietigend commentaar over deze studie van onze collega's bij Powerwatch:
The Mobile Telecommunications and Health Research Committee MTHR have spent £247,000 on a meaningless study published, four years after it was planned to be complete, in the BMJ today apparently to ''reassure parents'' that living near a mobile phone base station will not put their child's life at risk.
Most surprisingly, both Cancer Research UK and the NHS praise this study for its design, quality and also for the reassurance that the results will give parents and especially expectant mothers. That shows an almost complete lack of understanding of the complexity of EMF/RF epidemiology. In fact this study tells us nothing at all of practical use.
We were initially surprised that the BMJ had accepted this for publication given their excellent stance in recent years on the need for good quality scientific evidence. However, they have caveatted their publication of this paper with a thoughtful editorial by Dr John Bithell of Oxford University's Childhood Cancer Research Group. Dr Bithell rightly raises some of the concerns that we raise below and asks that: ...''before the risk is considered to be unfounded it is important to understand why the study may have missed a true effect''. Dr Bithell retired in 2004 after a long academic career at Oxford. We should be aware that it is all too often only retired scientists who can afford to speak out about the problems with some modern published ''science'' - they no longer have a career to look after. However, it is disappointing that he only chose to reference ''no effect'' studies (such as ICNIRP's) when there are plenty that have found concerning low-level RF exposure effects.
Maybe it is best that a good journal such as the BMJ publishes such dubious quality Government and Industry funded work (we hesitate to call it a scientific study) along with a caveat about how much we may be able to rely on its findings. Otherwise a less reputable journal might just publish it with no warning. There have been many recent examples of papers (especially about RF exposure) in seemingly good journals that have not been through a sufficiently rigorous peer-review process before being accepted and published.
It was never clear why this study was funded by the MTHR in the first place. There was no realistic chance of finding a link with childhood leukaemia or child brain tumours even if the study had been properly designed and controlled. The long history and ongoing debate about the associated doubling in incidence of childhood leukaemia and EMF exposure from powerlines and electricity substations, etc, has made it clear that no single short-term limited study will provide any firm answers.
Childhood cancer is, fortunately, rare. After over 70 years of research, it is clear that many factors are involved in what is almost certainly a multi-factorial multi-stage processes of initiation, promotion and development. The incidence of most childhood cancers has been rising fairly steadily since the second world war, though the rate of rise has actually slowed recently. There is no evidence of a new major causal factor coming in to play. One short-term study could not have the power to identify a single factor however well it was carried out. Since this study failed to even assess other sources of RF exposure (which are often higher for individuals than that from base stations) there was no conclusion that could be made about base station masts and childhood cancer.
The study title and protocol only specified mobile phone base stations and no other RF sources. The MTHR website description of the approved study states: ''The study will determine whether or not childhood cancer cases occur more commonly near mobile phone base stations than would be expected from the national distribution of births, but of itself it will not be able to say whether any excess risk near mobile phone base stations is causally linked to base station emissions. So why did the MTHR spend almost a quarter of a million pounds on funding this work? We note that Paul Elliott, the Principal Investigator, was a Member of the MTHR management group at the time the study was approved.
Who is Paul Elliott?
Paul Elliott is a Professor of Epidemiology and Public Health Medicine at Imperial College London. He is also the person who with his colleagues has, more often than not, claimed that their research has shown that environmental hazards, including Gulf War Syndrome, Electrical Sensitivity, TV broadcast masts, etc., are not likely to be ''real'' hazards.
He is the Principal Investigator (PI) of the Airwave health monitoring study of long-term health of police officers in relation to use of the TETRA communication system. He is also PI of the COSMOS international cohort study of mobile phone use and health, which aims to study 200,000 mobile phone users (90,000 from the UK) and their long-term health. This expensive study that includes four other European countries is not due to finally report for about 30 years and there are some serious questions about its resolving power to find anything - after that length of time even if they did confirm a real problem with mobile phone use it would be far too late to do anything precautionary. It would be like asbestos - with over 50 years time-lag from when it was banned in the UK until the peak of mesothelioma deaths that its dust caused. The UK part of the COSMOS is primarily funded by the MTHR and supported by the HPA.
He is Director of the UK Small Area Health Statistics Unit (SAHSU), largely funded by the Department of Health and Defra and now part of the new MRC-HPA Centre for Environment and Health. SAHSU claim that they are developing what is one of the largest epidemiological research programmes in the world on the potential health effects of non-ionising radiation. If the lack of meaningful science in this present study is anything to go by we wonder how and why they repeatedly get funding? Maybe to be the ''reassuring voice'' to tell us all to stop worrying, have some therapy and get a life.
What is wrong with this latest study?
Maybe the question should be ''What is right with this study''? A lot of hard work must have been put into the modelling and calculations to estimate the exposure from nearby base stations. The work would certainly have kept the team busy. However, having measured many hundreds of homes and base stations around the UK, we know that theoretical modelling is far from accurate - the real-life readings can be quite variable. Reflections, different building material properties, location and type of trees, etc, etc., greatly affect the RF exposure at a location - especially within a couple of hundred metres of a base station antenna. The quality of the modulation varies enormously as well - and that may be far more important than averaged out total exposure which is all this study attempted to evaluate.
By far the largest problem with this work is that it only considered calculated (but effectively only estimated) exposure from mobile network base stations and ignored all other sources of microwave and RF exposure. It states: ''Our models did not include information on other sources of radiofrequency exposure, such as from microcells or picocells, cordless phone base stations, maternal use of mobile/DECT phones during pregnancy, or radio and television transmitters... '' and ''..It has been estimated that one day's exposure from a base station at an incident level of 1-2 V/m (about 4.2-10 dBm or 2-10 mW/m2) corresponds to about the first 4 seconds of local exposure to the head and about 30 minutes of whole body exposure arising from the use of a mobile phone... 14 15''.
So it effectively admits that the other sources of RF exposure that they omitted to include would actually have often been stronger than the base station signals they modelled. This confirms that it was not looking at RF exposure, but just at base stations. In fact it is worse than that for they did not include ''microcell'' base stations which, in towns and cities often expose nearby homes to much higher levels than high-mounted macrocells. We ran an important story about this in 2005.
In our measurement work over the last 15 years, we have also found that DECT cordless phone and DECT baby monitors usually expose young children at home to higher levels of amplitude modulated RF than what enters the house from local base stations. Also, many mothers carry young children whilst using a mobile phone.
The study authors applied quite sophisticated corrections to their results - parental education, the deprivation index for the area, population density and population mixing - to do that and yet to completely ignore the other RF exposures means that this new work cannot, in our opinion, be classified as ''science''. That is not science, it is PR.
Should we be concerned about RF exposure and childhood leukaemia?
Given the recent time trends in incidence rates, it seems unlikely that chronic low-level RF exposure will increase the incidence of childhood leukaemia and other cancers. It seems an extraordinary choice to fund a study that just considered child cancers and calculated RF/microwave exposure only from cellular network base stations - it could tell you nothing at all about any possible association between RF and childhood cancer.
There are many adverse effects on well-being that have been repeatedly reported in populations living around mobile phone base stations (especially sleep disturbance, fatigue, depression, irritability, headaches, frequent infections, general body discomfort especially at night, allergies, etc - reported in detail elsewhere in these Powerwatch pages - see the our science section for a list of References). These are the things that should be being studied - but the MTHR has not funded any such studies.
Nor has the MTHR funded, despite requests, a study on the some 2000 low-height high-power base stations that the NRPB identified in the earlier MTHR funded study of base stations with antennas under 10 metres high. These are almost certainly the base stations that expose people most highly. At the time the NRPB report (W62) commented: ''It was noted that some 2000 of the 32,837 base stations, or around 6%, were radiating more than 5 watts at heights up to 10m. In conjunction with the MTHR project monitors, it was considered whether these transmitters should be included. It was decided that they should not be and that this project should concentrate on the low power sites in order to stay true to its original aim of considering microcells as low-height / low-power transmitters.'' The base stations that were ignored had transmitter powers up to 100 watts and the antennas are often mounted on the walls of residential buildings. The original study cost the MTHR £66,000. To extend it, as requested, to include another 2000 base stations would cost less that half this. The MTHR chose not to pay for this important further work. Instead it paid £247,000 for this Elliott study which has told us nothing useful. We question the basis of the MTHR's priorities.
There are studies showing elevated incidence of adult leukaemias in proximity to powerful TV and radio masts and to elevated occupation exposures. Also some on reduced academic and behavioural performance of children chronically exposed to RF. These certainly do not prove there is a problem, but they do suggest that a precautionary approach that reduces unnecessary exposure is sensible.
This study provides no justification for any assertion of safety to people living near mobile phone base station antennas.
Voor het origineel zie:
Van onze Belgische collega's van Beperk de Straling ontving Stopumts het navolgende strijdbare commentaar:
Deze studie is een regelrechte klucht. Is meer een marketing-stunt en een poging om mensen op een misleidende manier gerust te stellen dan wetenschap.
Sowieso is het zeer moeilijk geworden om het verband tussen masten en kanker nog te onderzoeken omdat er nu eenmaal geen niet-blootgestelde controlegroep meer bestaat waarmee je de ‘bestraalde’ groep kan gaan vergelijken; die masten staan namelijk overal.
Bovendien is er een hele resem ‘confounding’ factoren die het verband verdoezelen: blootstelling aan draadloos internet thuis en/of op het werk, draadloze DECT-telefoons, gsm-gebruik, tv- en radio-antennes, ...
Doordat deze studie geen rekening hield met deze factoren (er werd niet voor gecontroleerd) was het A PRIORI onmogelijk om een statistisch verband te ontdekken (!)
Genoeg andere studies wijzen wel degelijk en duidelijk op een verband met kanker. Zo zijn er bijvoorbeeld meer dan 20 onderzoeken die wijzen op DNA-schade.
En ook in de praktijk stelt men wereldwijd kankerclusters vast in de buurt van zendmasten, zie het overzicht dat Beperk de Straling samenstelde: www.beperkdestraling.org/index.php?option=com_content&view=article&id=76&Itemid=85 .
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