Occupational exposure and health effects
C1. Some workers are exposed all day to 60 microT magnetic fields (50Hz sinusoidal fields). At this exposure level, are there any real medical risks? Should we organise a medical follow-up? (Answer)
C2. A patient asked me if he runs a risk at his factory. He works at least 6 hours a week in an area near (i.e. within 8 meters) a 150 kV cable. Could you help me advise this patient? (Answer)
C3. We work in the vicinity of a 15 kV transformer station and from time to time, our computer screens flicker. We are upset about the effects on our health, especially as our employer does not accept to take any measurements. It there a law to force him to take them? (Answer)
C4. In our metallurgy sector, we use electric blasting furnaces that produce magnetic fields. Should we protect ourselves from them? (Answer)
C5. Should workers with pacemakers be careful and avoid working in the vicinity of high voltage powerlines and transformers? (Answer)
C6. What kind of equipment should be placed to protect workers against high electromagnetic fields from high voltage lines ? (Answer)
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C1. Some workers are exposed all day to 60 microT magnetic fields (50Hz sinusoidal fields). At this exposure level, are there any real medical risks? Should we organise a medical follow-up?
Although such exposure is quite significant compared to the ambient exposure of the general public (up to 200 nanoT in homes located near overhead powerlines and for measurements taken at distance from working electrical devices), even for people who live under a very high voltage line, the intensity is consistent with guidelines for professional exposure. International guidelines from the International Commission on Non-Ionizing Radiation Protection (ICNIRP) are 1000 microT during a day of work (8 hours in mean). The 60 microT that you mentioned is also under the value for the public, namely 200 microT (ICNIRP, 2010). These guidelines are based on proven and acute effects of 50-60 Hz magnetic fields.
For more information concerning guidelines, please consult our "Standards" pages.
To answer the question regarding the medical risk of professional exposure, we could say that, except for some cases with electronic implants, no harmful health effects have been demonstrated. The question of cancer (in particular leukaemia and brain tumours) remains in some reports, even if the risk is low and the confounding factors numerous in professional areas. The International Agency for Research on Cancer (IARC) has recently classified ELF magnetic fields in group 2B as possibly carcinogenic to humans on the basis of childhood (0-14 year old) leukaemia, but not on the basis of professional illnesses. Static electric and magnetic fields, as well as ELF electric fields, are in group 3: not classifiable as to their carcinogenicity to humans.
The question of neuro-degenerative disorders (Amyotrophic Lateral Sclerosis, Alzheimer disease...) is also raised, but too few data are yet available.
Concerning workers exposed to electromagnetic fields, the NIEHS (National Institute of Environmental Health Sciences) conclude the possibility of chronic lymphocytic leukaemia in their 1998 report. However, this was not confirmed by IARC in 2002.
About adult cancer and residential exposure, the IARC report concludes:
...a consistent association between residential exposure and adult leukaemia and brain cancer has not been established. For breast cancer and other cancers, the existing data are not adequate to test for an association with exposure to electric or magnetic fields.
About adult cancer and occupational exposure, the IARC report concludes:
... for intermediate or high magnetic field exposure categories. There was no consistent finding across studies of an exposure-response relationship and no consistency in the association with specific sub-types of leukaemia or brain tumour. Evidence for cancers at other sites was not adequate for evaluation.
No known organisation (WHO, Belgian RGPT - Règlement Général pour la Protection du Travail) recommends any particular medical follow-up for workers in the electricity area. Other hypotheses must be explored related to melatonin secretion or pseudo-iron deficiency, but this is more a concern of future research than a question of medical follow-up.
You can see that this is a complex question, even if no proven effect has been demonstrated for workers exposed to this level of magnetic field intensity. More information is available at the following links:
- A fact-sheet has been prepared by NIOHS (National Institute for Occupational Safety) for workers:
- Here is some information concerning World Health Organization (WHO) conclusions and the classification of magnetic fields in Group 2B as "possibly carcinogenic to humans": http://www.who.int/docstore/peh-emf/publications/facts_press/efact/efs263.html
- The WHO's position related to the precautionary principle: http://www.who.int/peh-emf/meetings/en/Lux_final_rapp_report.pdf
C2. A patient asked me if he runs a risk at his factory. He works at least 6 hours a week in an area near (i.e. within 8 meters) a 150 kV cable. Could you help me advise this patient?
To answer your question, it is helpful to know more about the field intensity levels to which your patient is exposed. ACE team can make the necessary measurements.
Concerning health effects and EMF exposure, the debate is still open. But various reports of experts published, in the last few years, have reached the same conclusion concerning cancer.
You will find information in To be read page (list of reports and books available on the web).
Some fact-sheets have been prepared by the World Health Organization (WHO), and are available here. Also, here is a summary of the report written by the International Agency for Research on Cancer (IARC), wherein experts have evaluated carcinogenic risks related to EMF.
For questions other than those related to cancer, such as neuro-degenerative disorders, sleep disorders, headache, there are still very few answers.
C3. We work in the vicinity of a 15 kV transformer station and from time to time, our computer screens flicker. We are upset about the effects on our health, especially as our employer does not accept to take any measurements. It there a law to force him to take them?
Around a transformer station, 50 Hz electric and magnetic fields are normally measured. You must take into account that computer screens are more sensitive to magnetic fields than human beings: 0.5 microteslas are sometimes sufficient to make the screen flicker. For adults, beyond 100 microteslas (the present standard proposed by ICNIRP), it is not likely to have any effects on health.
Only the occupational physician or the safety coordinator are qualified to deal with this kind of problem. These persons could make a risk analysis and ask a lab to make measurements (further information on competent labs). If these persons are unable to help you, you can contact the labour inspection of your country. In Belgium, you will find further information at this address: http://www.meta.fgov.be/.
A European directive exists that limits the occupational exposure to EMF. However, this directive has not yet been passed in the Belgian law and thus is not applicable in Belgium yet. This standard will impose making risk analysis and limiting exposure. Member States are going to enforce the laws, regulations and administrative provisions necessary to comply with this Directive no later than 31 October 2013. Further information on the content of this directive are available at: http://europa.eu/
However, the intensity of fields that might interfere with your computer are well below the values that cannot be exceeded as defined in the European directive (500 microtesla for magnetic field and 10 kV/m for electric field).
Moreover, new computer screens are usually less sensitive because their electronic components are better protected against this kind of interference (see also question A3).
C4. In our metallurgy sector, we use electric blasting furnaces that produce magnetic fields. Should we protect ourselves from them?
It is obvious that induction furnaces can lead to relatively high exposure to magnetic fields. Thus, it is necessary to make a risk analysis and measurement of electric and magnetic fields (further information?) in order to comply with exposure limits defined in 2012/11/EU directive amending directive 2004/40/EC. This new European directive is intended to limit the exposure of workers to these fields and will have to be transposed in the Member States in 2008.
You will find below the text of the directive and some websites that could give you further information on the subject :
- 2012/11/EU directive amending directive 2004/40/EC of the European Parliament and of the Council of 29 April 2004 on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields).
- WHO EMF project : Fact and information sheets involving electromagnetic fields and public health and EMF world wide standards.
- "Standards" page of the BBEMG website.
C5. Should workers with pacemakers be careful and avoid working in the vicinity of high voltage powerlines and transformers?
First of all, it's a question of specifying that present directives/recommendations (EU, ICNIRP, ACGIH) do not take account people with pacemakers.
Technically, you need to know that pacemakers in a bipolar mode are a lot less sensitive to fields that the ones in a unipolar mode (adjustment of sensitivity threshold also plays a part). Unipolar pacemakers could be disrupted by electric field intensities lower than the ones recommended by directives and recommendations, sometimes 2kV/m. People with this kind of pacemaker should avoid being in an area where electric fields exceed 1.5 kV/m to have a sufficient safety margin.
In some places, the electric field around high voltage powerlines can exceed 1.5kV/m. However, keep in mind that field intensity varies with line configuration, voltage and the distance from the line.
Concerning magnetic fields, bipolar pacemakers with threshold sensitivity greater than or equal to 2mV, no interference has been detected under 100 microTesla. In the study of Souques et al (2004), more or less 3% of pacemakers were transitory disrupted by magnetic fields, but never under 45 microTesla. This value can be considered as the possible perturbation threshold for a unipolar pacemaker (in one room or in both). Practically, maximal level of magnetic field under a high voltage powerline (measured with respect of legal safety distances) are always below 50 microTesla
To summarize the situation, according to Souques et al (2004),
"Avec les pacemakers actuels, réglés en mode bipolaire avec une sensibilité ventriculaire courante (2mV en général), le risque d'interférence est quasi inexistant pour les expositions rencontrées couramment. Les pacemakers réglés en mode unipolaire ou avec une sensibilité importante sont plus sujets aux interférences. [.] Il est recommandé de ne pas utiliser de petits moteurs (type appareil de bricolage, perceuse...) à proximité immédiate du boîtier du pacemaker."
("With actual pacemakers, in a bipolar mode with a current ventricular sensitivity (generally 2mV), interference risk is almost impossible for usual exposures. Pacemakers in a unipolar mode or with a high sensitivity are more subject to interference. [...] The use of devices with tiny motors (e.g. DIY devices, drills and so on) are not recommended close to pacemakers.")
Unipolar pacemakers are increasingly less used in new implantations. However, on the other hand, it happens that pacemakers are changed, when the batteries are weak, without changing the probes placed in the past. Practically, until now, nobody has reported a mishap or incident caused by walking under a high voltage powerline. It should be more dangerous to stand a while under the line, if the person has an unipolar pacemaker with high sensitivity (<2mV).
Let us add that pacemaker disruptions are not as dangerous as we might imagine because the apparatus quickly restores its own rhythm. In most cases, the person fitted with the pacemaker is not conscious of such a disruption.
We advise you to ask your heart specialist which kind of pacemaker is implanted, its programming, and its immunity level to electric and magnetic fields. With these details, an occupational physician will be able to inform workers on the subject.
Souques M, Magne I, Lambrozo J. Implantable cardioverter defibrillator and 50-Hz electric and magnetic fields exposure in the workplace. Int Arch Occup Environ Health, 2011 Jan;84(1):1-6 (pdf).
Souques M, Magne I, Trigano, A., Franck, R., Héro, M., Nadi, M., Audran, F., & Lambrozo J. Implants cardiaques et exposition aux champs électromagnétiques 50 Hz en environnement professionnel. Archives des Maladies Professionnelles et de l'Environnement, 2008, 69:547-552. (pdf).
Hocking B., & Hansson Mild K. Guidance Note: Risk Management of Workers
With Medical Electronic Devices and Metallic Implants in Electromagnetic Fields. International Journal of Occupational Safety and Ergonomics (JOSE), 2008, Vol. 14, No. 2, 217–222. (pdf)
Souques, M. Influence des champs électromagnétiques non ionisants sur les dispositifs cardiaques médicaux implantables. La Presse médicale, 2004 Dec 18; 33(22):1611-5.
C6. What kind of equipment should be placed to protect workers against high electromagnetic fields from high voltage lines ?
In a working environment with high electromagnetic fields, workers have to enquire the Health and Safety Dpt of their company. This department will perform a risk analysis of the workplace and provide an appropriate action plan, if needed.
Further information available in the European website.
Suggestions and comments are welcome.
Please feel free to contact us if needed.