Monitoring campaign in children (2001-2009)
G. Decat, L. Deckx, D. Wilczek, G. Meynen
Monitoring campaign of the 50 Hz magnetic field for the estimation of the proportion of Belgian children exposed to the epidemiological cut-off points of 0.2, 0.3, and 0.4 microtesla
On base of the biologically not-confirmed but still holding epidemiological relation between the ELF magnetic field exposure and childhood leukemia,VITO performed a measurement campaign in the framework of the BBEMG-projects (2001-2009). The campaign was performed on in Belgium living children under 15 and its aim was to know the field strength these children are exposed to on the one hand and what their probabilities are to be exposed to magnetic field of cut-off points of 0.2, 0.3 and 0.4 µT on the other hand. In this way the general public, authorities and others could gain insight in the Belgian children population at risk if a causal relationship should exist. In magnetic safety and health decision making processes we have to underline that a cut-off point is not a reference level of an exposure standard or guideline but an epidemiological arbitrary fixed boundary value between a control (exposure < cut-off value) and an exposed group (exposure > cut-off value). Since not only power lines and/or other electrical facilities produce ELF magnetic fields but also among others residential (distribution lines etc.), operating electrical household and school appliances generate magnetic fields, all these exposure explanatory variables were taken into account too. Beside the two main objectives of the study we also tried to define the household and the power-lines contribution parts to the 0.4 µT exposure of the children. We also compared the possible background exposure variation in houses by putting "on" and "off" the electrical appliances and moreover, we verified the waveform and the harmonic content of magnetic fields generated by the household appliances too.
The age of the children participating in the campaign was less than 15 years. They were selected by means of a special selection protocol via their parents working in different institutes or universities on the one hand or via local authorities or the director of primary schools on the other hand. The sample consisted of about 800 children from which about 83% (± 650) valid analyses could be drawn. For performing the individual exposimetry each child received an EMDEX Lite ELF monitor (Enertech consulting) for 24 h. They also received a well-documented measurement protocol describing the use of the meter and underlining how to avoid measurement bias. During the sleeping time the meter was advised to be placed under the mattress of the child's bed, during the non-sleeping period at home it was advised to wear the meter on their body if possible and during the school time the meter had to be placed in their satchel. The data analysis and data stratification for home and school exposure was performed by means of the EMDEX Calc software and a log-form that each child had to complete for indicating time and place where the magnetic field was registered .
The measurement of the possible background exposure variation due to operating household appliances was recorded simultaneously during 24 h by placing one EMDEX Lite meter in the bathroom, dining-room, kitchen, sitting area and bedroom of a one-storey house and a non-storey house respectively.
The Fourier analysis of the magnetic field generated by the household appliances was performed by means of the ELT-400 (Narda) meter combined with the FLUKA low frequency spectrometers.
The contribution of both the power line and the household appliance exposure was verified by comparing the power line modelled 0.4 µT exposure and the 0.4 µT household measured exposure.
Concerning the first main objective of the study we conclude that:
- the individual childhood time integrated median exposure to the ELF magnetic field is very weak at school (0.01µT)and at home (0.02 µT);
- The time integrated arithmetic mean exposure (0.02 µT at school, 0.06 µT at home, 0.11 µT during sleep) is substantial greater than the median one;
- due to measurement bias the arithmetic mean overestimates the real exposure as compared to the median and the geometric mean;
- the time integrated median is the best estimator of the real childhood exposure: median and geometric mean exposure gives similar results;
- the choice of bad estimators leads to wrong conclusions;
- the background exposure is not influenced by operating household appliances and devices;
- the harmonics generated by the household appliances do not underestimate the wideband reading of the ELF EMDEX LITE exposimeters;
- no correlation was found between the strength of the exposure and the explanatory variables. The lack of correlation between the distance of the houses to power lines and the field strength suggests that the questionnaires for listing the explanatory variables were not correctly completed;
- the exposure of the children is negligible as compared to the reference level of the Recommendations of the Council of Europe;
- the median exposure is much weaker than the 0.2 µT guide value of the Flemish indoor quality standard.
As for the second main objective we conclude:
- that if a causal relationship exists somewhat more than 24000 children in Belgium are at risk for childhood leukaemia by exceeding the 0.4 µT cut-off point at home;
- that when applying the Flemish 0.2 µT indoor quality standard about 54651 children under 15 years in Flanders are living in an indoor environment from which the magnetic field desirably but noet obligatory has to be cleaner. If we extrapolate this data to the Belgium populations under 14 it concerns about 88300 children;
- that the frequency of children exposed to cut-off points of 0.3 and 0.4 µT are in line with the data of the WHO and other countries respectively;
- that the percentage of children exposed to the cut-off exposure is less in schools than at home;
- that at home the highest frequency is generally observed during sleep;
- that the proportion of children exposed to a certain cut-off point is different when the median or the arithmetic mean exposure is used. The arithmetic mean exposure gives an overestimation of the real cut-off frequency;
- that there is a tendency that household appliances and other factors than power lines doesn't influence the global frequency of children exposed to 0.4 µT.
As for the sample we can conclude that though it was well balanced between the Brussels, Flemish and Walloon regions, the sample size was only about 0.04% of the Belgian children's population under 15 whereas in other countries it was lower. Because statistic is a compromise between funding and reliability (increasing funding gives increasing sample sizes and consequently increasing confidence) we never know how much funding is needed to set up an experimental design able to overcome uncertainty or a substantial part of it. Though the most suitable statistics were used for drawing the most acceptable/reliable conclusions, we'll never be sure at 100% that we didn't miss some unknown or known explanatory variables which could have led to more comprehensive and explanatory conclusions and recommendations.
As for the validation of the results, the results of the experiment are very useful/important for governmental and non-governmental bodies, stakeholders and all other bodies which have to take decisions concerning the possible impact of the B-field exposure on public health and/or town, country and environmental planning. Electricity distributors might be interested in the local exposure level for their new power line planning strategy. Local authorities can use the data for new housing development projects and national and even international governmental bodies might use the data for risk management and risk communication as well as health options in general.
G. Decat, L. Deckx, D. Wilczek, G. Meynen
The objectives of the project were multiple. The first goal was to estimate the magnitude of the magnetic flux density (B-field) to which children between 0 and 15 years old are exposed during various activities at home and at school, respectively. The second aim was to estimate the proportion of children living in Belgium who are exposed to different epidemiological cut-off points. Survey results cover the monitoring of ELF magnetic fields in 251 children aged between 0 and 14 years. The results are the following:
- the median is the 'best estimator' of the 24 hours' B-field registrations for assessing the real exposure at home, at school or at kindergarden or nursery;
- we are 95% confident that the average weighted median of the overall exposure is situated between 0.03 and 0.05 µT;
- our findings agree with those of international literature: about 4% of children living in Belgium are exposed to at least 0.4 µT;
- the 4% exposure to 0.4 µT isn't only a result of power line exposure, but from a combination of electromagnetic sources;
- no correlation is found between the magnitude of B-field exposure and the most common explanatory variables possibly related to B-field exposure.
So far the sample size of children tested is too small for drawing reliable conclusions related to the objectives of the experiment .
The results of the experiment are very useful/important for governmental and non-governmental bodies, stakeholders and all other bodies which have to make decisions concerning the possible impact of B-field exposure on public health and/or town, country and environmental planning. Electricity distributors might be interested in the local exposure level for their new power line planning strategy. Local authorities can use the data for new housing development projects and national and even international governmental bodies might use the data for risk management and risk communication as well as health options in general.
Note: the references of confidential reports for industrial purposes are not in the list.
Decat G., Wouters, G. and Kretzschmar J.G. (1993). Quantification of the Radiation Leakage of Domestic Microwave Ovens. 3rd International Symposium Hygiene and Health Management in the Working Environment. Ghent, 41-45, 1993
Decat G., Wouters G. and Kretzschmar J.G. (1993). Survey on Microwave Ovens: A Modelling Approach on Radiation Leakage. 28th International Microwave Symposium, Montréal, Canada, 170-175.
Decat, G. en Kerckhofs, R. (1995). Evaluatie van elektrische en magnetische velden afkomstig van Belgische hoogspanningslijnen bij normale exploitatie. Tijdschrift Energie & Milieu 3 mei/juni, 118-122.
Decat, G. and Van Tichelen, P. (1995). Electric and Magnetic Fields of Domestic Microwave Ovens Quantified under Different Conditions. The Journal of Microwave Power & Electromagnetic Energy. International Microwave Power Institute, 30(2):102-108.
Decat, G. and Van Tichelen, P. (1995). Magnetic Field Monitoring of a Microwave Oven Operating With and Without Metal Housing: A New Approach. Microwave World, 16(2):15-19.
Decat G. and Van Tongerloo J. (1998). Magnetic field monitored in houses under 50 Hz high- voltage transmission lines of 70, 150, 220 & 380 kV. Air Pollution VI, Editors: C.A. Brebbia, C.F. Ratto, H.Power, TM WITPress Computational Mechanics Publications Ed, 237 - 246.
Decat, G. and Van Tongerloo, J. (1998). Monitoring of the Magnetic Fields in Houses under High- Voltage Overhead Transmission Lines of 150, 220 and 380 kV. International Journal of Environment Pollution, 9(4):341 35.
Decat, G. en Van Tongerloo, J. (1998). Monitoring van het magnetisch veld in woningen onder de Belgische hoogspanningslijnen met bedrijfsspanning van 70, 150, 220 & 380 kV. Energie & Milieu nr. 2 - maart/april.
Decat, G., Lambert, B. and De Rijck K. (2000). Static and alternating 50 Hz Magnetic Fields in our Living and Working Environments. Vito Conference Proceedings on 'Safety in living and working environments: promotion of a network for the study of risk factors'. Organized by: Italian Embassy in Belgium , Vito, ISPESL, IST. pp. 31-33, December 15 th , 2000.
Decat, G. (2001). Relative exposure index for the relation between the personal and the stationary home magnetic field exposure close to and far away from power lines. EBEA-2001 Proceedings, pp. 136-139, September 2001 .
Decat, G., De Ridder, M. en Verschaeve L. (2001). Niet-ionsierende straling: achtergronddocument van het MIRA-rapport: http://www.vmm.be/, Vlaamse Milieumaatschappij (VMM), december 2001.
Decat,G., De Smet, J., Deckx, L., Lambert, B. (2001). Evaluatie van het persoonsgebonden 50 Hz magnetisch veld tijdens het AC elektrode- en het AC TIG-lassen in de industrie en het onderwijs. Proceedings, BIL-Research, Veiligheid en gezondheid bij het lassen. Studiedag Belgisch Instituut voor Lastechniek, pp. 1-9, november, 2001
Decat, G. (2002). Representativeness of 24 h and 48 h measurements of the magnetic field exposure for epidemiological purposes and the ratio between the dynamic and static exposure for people living below high voltage transmission lines. Piers 2002 Proceedings, Progress in Electromagnetic Research Symposium, July 1-5, 2002, Cambridge, Massachusetts, USA, Published by the Electromagnetic Academy, Cambridge USA, p. 691.
Decat, G., Crasson, M., Peeters, E., Van Loock, W. (2003). Optimal sampling time for the exposure assessment of the magnetic field for epidemiological purposes. EBEA-proceedings 2003.
Decat, G., Peeters, E., Smolders, R. (2003). Tijdsreeksen en GIS-model voor het in kaart brengen van de blootstelling aan elek trische en magnetische velden van hoogspanningslijnen in Vlaanderen. (rapport wordt binnenkort door VMM gepubliceerd)
Verwaest, Kristof (2003-2004). Inventarisatie van niet-ioniserende straling veroorzaakt door verkeerscontrole van de politie voor de bevolking in Vlaanderen. Afstudeerverslag voor het bekomen van de titel van Milieukundig Ingenieur. Promotor Gilbert Decat.
Decat, G. (2004). Relative e xposure index for the relation between the dynamic and sationary exposure of the magnetic field in the working environment. Proceedings. Int. Symposium 3rd Workshop on Biological Effects of EMFs, Kos, Greece, 4-8 October 2004.
Decat, G. (2004). Elektr omagnetische velden in de werkomgeving. Milieutechnologie nr 5 mei 2004 - Kluwer uitgevers.
Decat, G., Peeters E., Smolders R., Bossuyt M. (2004). GIS modelling for e stimating the proportion of children exposed to the elf magnetic field of overhead power lines in Flanders (Belgium). Proceedings - Asia-Pacific EMF Conference Electromagnetic Field Research Jan. 26-30, 2004 Bangkok, Thailand.
Verschaeve, L., Decat, G., Maes, A. (2004). Inventaris van blootstellingsniveaus van niet-ioniserende straling voor de bevolking in Vlaanderen, literatuurstudie. Publicatie beschikbaar via website: http://wwwmina.be/milieugezondheid.html . Aminal, DTG/OL200100709/3097/M&G)
Decat, G., M. Wevers , P. Kessels, G. Meynen, K. Scheepers, K. Duyssens, L. Deckx, P. Van Tichelen, Z. Grabarczyk , G. FortisInt. (2005). Is electrostatic discharge produced under office working conditions in such a way that it can trigger lipoatrophia semicircularis? Proceedings Workshop on ELECTROMAGNETIC FIELDS IN THE WORKPLACE. Warszawa, Poland, September 5-7, 2005, pp. 17 - 22.
Decat G. (2005). Modelling the residential ELF magnetic field risks of power lines and some considerations about the risks in terms of dynamic exposure. Proceedings XXVIIIth Gneral Assembly of International Union of Radio Science (URSI). Vgiyan Bhavan, New Delhi, India, October 23 - 29, 2005, pp. 157.
Decat G., Deckx L., Peeters E., Smolders R., Bossuyt M. (2005). Residential and dynamic exposure to the 50 Hz magnetic field from power lines and estimation of the risks. Proceedings: 2 nd workshop of electromagnetic compatibility. Technical University Cluj-Napoca, September 22-23, 2005. pp. 25-29.
Decat, G. (VITO, Belgium), Falsaperla, R. & Rossi, P. (ISPESL, Italy), Hietanen, M. (FIOH, Finland), Karpowicz, J. & Gryz, K. (CIOP, Poland), Sandström, M. & Hansson Mild, K. (NIWL, Sweden), Ravazzani, P. (CNR, Italy). How to manage occupational high exposure static, ELF and RF electromagnetic fields according to the workplace electromagnetic field Directive 2004/40/EC of the European Council/Parliament. Proceedings 2005 Australien Radiation Protection Society Conference. 30 Years of Radiation Safety, Research and Practice in Australasia. Rydges, Melbourne, November 13-16, 2005, pp. 30.
Karpowicz J., Decat G., Gryz K., Falsaperla R., Hansson Mild K., Sandström M., Rossi P., & Hietanen M. (2006). Problems and gaps for the assessment of occupational exposure - The EMF-NET MT2 experience. MT2-WORKEN - EMF. Int. Exposure related risk in the Working Environment. Int. Workshop on EMF dosimetry" ICNIRP-proceedings , Berlin , March 20-22, 2006 .
Sandström, M., Decat, G., R. Falsaperla, R., Gryz, K., Hansson Mild, K., Hietanen, M., Karpowicz, J., Rossi, P. (2006). MT2-WORKEN - EMF exposure related risk in the working environment: State of the art report. Bioelectromagnetics Soc annual meeting. Cancun, Mexico, June 11-15, 2006, pp 112.
Karpowicz, J., Decat, G., Falsaperla, R., Gryz, K., Hansson Mild, K., Hietanen, M., Sandström, M. (2006). Assessment of occupational exposure to EMF. 28th International Congress on Occupational health, ICOH. Milano, June 11-16, 2006, pp 435.
Decat, G., L. Deckx , G. Meynen, E. De Graef , F. Jonlet (2006). Magnetic Fields of Induction Heaters in the Framework of Directive 2004/40/EC of the European Parliament and of the Council.
Int. Journal of Occupational Health and Ergonomy (JOSE), 12(2):169-76.
Decat, G., M. Wevers , P. Kessels, G. Meynen, K. Scheepers, K. Duyssens, L. Deckx, P. Van Tichelen, Z. Grabarczyk , G. FortisInt. (2006). Is electrostatic discharge produced under office working conditions in such a way that it can trigger lipoatrophia semicircularis? Accepted for publication in the Int. Journal of Occupational Health and Ergonomy (JOSE).
Decat, G. Meynen, G., Peeters, E. Van Esch, L. Deckx, L. & Maris, U. (2007). Modellering en GIS-toepassing voor het bepalen van de blootstelling en het epidemiologisch risico van het 50 Hz magnetisch veld gegenereerd door de ondergrondse hoogspanningskabels in Vlaanderen Studie uitgevoerd in opdracht van de Vlaamse Milieumaatschappij (VMM) - VITO-rapport 2007/IMS/R/426
Decat G., Deckx L., Broekx K., Hanson-Mild K. (2009). Speciale Veiligheid/Special Safety, Blootstellling aan elektromagnetische velden/Exposure to electromagnetic fields. Lastechniek (Welding Technique), april 2009/April 2009, Jaargang 75/Edition 75, p. 20 - 23.
Hansson Mild, K., Alanko, T., Decat, G., Falsaperla, R., Gryz, K., Hietanen, M., Karpowicz, J., . Rossi, P., Sandström, M. (2009). Exposure of workers to electromagnetic fields. A review of open questions to Exposure Assessment Techniques. Int. J. of Occupational Ergonomics (JOSE) 2009, Vol. 15, No.1, p. 3 - 33.