Leukaemia and brain tumours in children
In order to examine the link between child cancer and possible environmental causes the WIV-ISP first made a literature review, scrutinising numerous studies from abroad. The review focussed on leukaemia and brain tumours because those cancers represent more than half of all cases of child cancer.
Leukaemia is cancer of the white blood cells. Those white blood cells multiply abnormally fast, fill up the bone marrow and disturb the production of normal blood cells. Genetic factors can play an important role in the development of all types of cancer but external factors, like biological, physical and chemical elements, can also have their influence.
Brain tumours are the solid tumours children are most commonly affected by. Again, there can be underlying hereditary factors but biological (SV40), physical (ionising radiation) and chemical elements (nitrosoamide compounds) can also have an influence on the development of brain tumours.
Child leukaemia in the vicinity of nuclear sites
In a second stage, the WIV-ISP carried out a study to examine the risk of catching acute child leukaemia in the vicinity of nuclear sites in Belgium. The aim was to verify whether child leukaemia occurs more often in the vicinity of nuclear sites in Belgium than in other areas. Statistical data were used to detect clusters (a ‘cancer cluster’ means that cancer occurs uncommonly often in a certain area and in a certain time span). The following data were used: data on population, data on socioeconomic status and income and data onurban versus rural residence, and data on cancer incidence.
The WIV-ISP examined data from 2004 until 2008. Child cancer refers to cancer in children from 0 to 14 years old. In the period 2004-2008, child leukaemia was diagnosed 420 times. Just like in other industrialised countries, child leukaemia peaks at the age of 2 to 5. The study was an ecological study into the nuclear installations of class 1 (harmful to hazardous installations), taking into account areas within 20 kilometres of the sites. As no Belgian city is situated within 20 kilometres of the nuclear reactor of Borssele (in the Netherlands), this site was not included in the study.
The analysis made by the WIV-ISP showed that acute child leukaemia does not occur more often within 20 km of the 5 nuclear sites than in other areas. No increased numbers of child leukaemia have been found, neither in the vicinity of the power stations of Doel and Tihange nor in the vicinity of the power stations of Mol and Fleurus. Not a single case of child leukaemia has been reported for the Belgian territory in the vicinity of the power station of Chooz. Figures about the area situated on the French territory were not available, however.
Opposite results produced by a French study
A recent French study, however, contradicts the results of the WIV-ISP analysis. According to this study conducted by the INSERM (Institut national supérieur des Études et de la Recherche médicale)and the IRSN (Institut de Radioprotection et de Sûreté nucléaire), children under 5 living within a radius of five kilometres of a power station, are twice as likely to have leukaemia than their peers living further away. France is the European country that has the most nuclear power stations on its territory (58). The type of power station does not make a difference for the development of leukaemia.
Comments on the WIV-ISP study
The WIV-ISP points out that its own study has its limits:
- The 20-kilometre radius is a distance that was chosen arbitrarily and that largely exceeds the 5-kilometre radius of the French study.
- The Belgian data available only refer to a very restricted period of time. The study is only based on data from 2004 until 2008 as it is only from 2004 that figures about the entire country have been available. The figures relating to the period after 2008 are still unclear.
That is why the WIV-ISP advises to repeat this study in Belgium in about 5 years, once more data will be available.