Magnetische velden van hoogspanningslijnen en leukemie bij kinderen

In response to the conclusion of the Health Council of the Netherlands that 'there is a reasonably consistent association between the occurrence of leukaemia in children and residence near overhead power lines' the Ministry of Housing, Spatial Planning and the Environment (VROM) requested RIVM to investigate what the consequences would be for the Netherlands if this association was found to be a result of a causal relationship between the strength of the magnetic fields due to these lines and the occurrence of leukaemia in children. Until now, experimental research has failed to indicate any plausible biological mechanism that supports a causal relationship between exposure to extremely low-frequency magnetic fields and the occurrence of any form of cancer. RIVM considers the results of two recently published pooled analyses a better starting point for describing the risk of leukaemia in children than the information from the individual studies or from meta-analyses performed previously. In the RIVM study values for the relative risk as a function of the magnetic field were derived from these two pooled analyses. The exposure situation in the Netherlands was determined using estimates of the magnetic field at several distances from the power lines. The additional individual risk and potential number of extra cases of leukaemia in children were calculated on the basis of the number of persons living within these distances. The additional individual risk in the RIVM study is defined as the risk children run of developing leukaemia due to living in a certain magnetic field near a power line. There are uncertainties about the form of the dose-response relationship. Therefore, the relative risk can only be concluded to be possibly elevated at field strengths somewhere above between 0.2 and 0.5 microtesla. On the basis of the results of the two pooled analyses, the additional individual risk for children who live in areas where the magnetic field exceeds 0.3 to 0.4 microtesla to develop leukaemia was found in the Netherlands to be 3 per 100,000 per year at the most. There are uncertainties in the number of children living in these magnetic fields, partly because of uncertainties in the estimates of the magnetic field as a function of the distance from power lines. When these estimates are used, the number of extra cases of the total 110 new cases each year is estimated at 0.2 to 1 per year. Since the total exposure to all sources of extremely low-frequency magnetic fields in the Netherlands is insufficiently known, further investigation of this exposure is recommended