The idea of a field is used in physics to indicate the influence of an object on its surroundings.
In the case of electricity, all electrical charges produce an electric field. The higher the voltage of a device or installation, the greater the electric field generated. Its unit of measurement in the international system is V/m (volt/metre) and this value decreases rapidly with distance.
A magnetic field is caused by the displacement of electric charges (current circulation). The higher the current intensity, the greater the magnetic field. Its unit of measurement in the international system is T (tesla), and as occurs with the electric field, the value of the magnetic field decreases very rapidly with distance.
For very low frequencies, such as 50 Hz (this is known as industrial frequency and is the frequency at which electricity is produced, transported and distributed in Spain), these fields are independent of each other. Therefore, the expression '50 Hz electromagnetic fields' is not correct. It is more appropriate to speak of '50 Hz electric and magnetic fields'.
Non-ionising radiation is radiation whose energy is not powerful enough to break molecular binding and consequently cause alterations in the cells of organisms.
Electric and magnetic fields at 50 Hz are in the lowest region of the electromagnetic spectrum, i.e., they are very low-energy waves in the area that is furthest from ionising radiation and are incapable not only of breaking binds but also of creating other effects that take place at higher frequencies, such as cell overheating.
The term 'scientific community' refers to an international group of scientists who, due to their work, research and discoveries in a specific field, have become members of study committees, editorial boards of scientific journals, national scientific academies and research centres with a rank similar to that of Spain's Centro Superior de Investigaciones Científicas (Higher Centre of Scientific Research), the Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (Centre for Energy, Environmental and Technological Research) or the Real Academia de Ciencias Físicas y Naturales (Royal Academy of Physical and Natural Sciences).
The research and conclusions of these specialists must be circulated in a series of specialised journals that are listed and evaluated by the Journal Citation Reports, published by the Institute of Scientific Information. As a result, scientific controversy regarding a specific area of knowledge can only occur when differing criteria are posed by the members of this community, which is the trustee of shared global knowledge. In such a case, those who disagree must support their findings with evidence. If they do not, but continue to stand by their postulates, they are self-excluded from this scientific community.
All the international scientific institutions and committees of experts that have studied this subject in recent years agree that electric and magnetic fields generated by electrical installations do not cause harmful effects in the long term (i.e., diseases) and therefore do not pose a public health hazard.
The conclusions reached by the scientific community are:
No biophysical or biochemical mechanisms are known that can explain how electric and magnetic fields generated by electrical installations might cause long-term harmful effects.
All epidemiological studies combined have not found an association between working or living near electrical installations and an increase in diseases. Laboratory experiments indicate that fields generated by electrical installations do not cause harmful effects.
The Spanish Ministry of Health and Consumer Affairs has arrived at this same conclusion in its technical report Electromagnetic Fields and Public Health [PDF] (*) drawn up by a committee of experts and made public in May 2001:
"It can not be affirmed that the exposure to electromagnetic fields within the limits established in the Recommendation of the European Council (1999/519/EC) causes adverse effects on the health of humans. Therefore, the Committee concludes that compliance with the aforementioned recommendation is sufficient to guarantee the protection of the population".
For frequencies of 50 Hz, these limits are 5000 V/m for the electric field and 100 microteslas for the magnetic field.
As regards exposure to very high levels of electric and magnetic fields, it is a known fact that this type of exposure can pose a health hazard. Specifically, sufficiently intense magnetic fields can cause direct stimulation of the peripheral nerves and muscle tissue. The purpose of national regulations concerning exposure is to prevent these effects by establishing limits on levels of exposure that must not be exceeded.
Inside homes, fields can vary from 150 microteslas and 200 V/m at a few centimetres from certain domestic appliances to less than 0.02 microteslas and 2 V/m in the middle of many of the rooms.
Domestic appliances with the highest magnetic fields are those that require high current intensity (for example, vacuum cleaners, microwave ovens, washing machines, dishwashers, blenders, electric can openers, electric razors). Of all the domestic appliances studied, only microwave ovens, washing machines, dishwashers and electric can openers generated fields over 0.2 microteslas measured from a distance of 1 metre.
Electric fields generated by power lines have a low capacity of penetration into buildings, and therefore there is very little correlation between electric and magnetic fields inside homes.
As regards the workplace, exposure to levels higher than 100 microteslas and 5000 V/m has been observed in certain workplaces (for example, in arc welding and cable assembly work). In normal electricity-related jobs, average exposure varies between 0.5 and 4 microteslas and 100-2000 V/m.
Measurements should be taken with a calibrated gaussmeter at multiple points and for an extended period of time, since these field levels are liable to high space-time variations. Fortunately, magnetic fields are much easier to measure than electric fields. This is due to the presence of conductors (including the body of the individual carrying out the measurement) that distort the electric field and render measurement difficult. This does not occur with magnetic fields.
It is important for the person that is measuring to understand the difference between emission and exposure. This may seem obvious but there are many people, including some scientists and expert physicists, who place the meter next to the source and compare this level with an exposure standard.
In the case of distribution lines and transformers, magnetic fields can vary considerably over time, since the fields are proportional to the current in the system. A reasonable measurement must be sought over time, with knowledge of previous and current electricity usage.
Our body constantly generates energy to perform its vital functions. Natural currents within an organism ranging between 1 and 10 mA / m2; which is the levelare necessary for proper functioning of the heart. It is shown that an induced current within this range does not produce biological effects. With these values as reference, the ICNIRP (and the European Union Council),) as a precautionary measure, established a establishes the level of frequency of 50 Hz, in 10 kV / m and 500 Î¼T for workers and 5 kV and 100 Î¼T for the general public
A heart pacemaker is an electronic device that detects the electrical activity of the heart and stimulates its contraction by sending electrical impulses to certain areas when it´s needed. It consists of a generator and a wire (electrode) that stimulates a specific area of the heart. The electrode configuration can be unipolar or bipolar, with the possibility of interference by an external electromagnetic field greater in the unipolar pacing than inon the bipolar. In Spain the majority of patients have installed bipolar devices.
In addition to the different configurationsconfiguration, pacemakers are calibrated according to the sensitivity of each patient, so that theirthe response in the presence of electromagnetic fields is distinct.different. A pacemaker, along with other implantable medical devices, are findcovered by Directive 2007/47/EC of the European Parliament and Council of September 5, 2007. This Directive states that "The devices must be designed and manufactured in such a way as to remove or reduce as much as possible (...) Risks associated with... predictable environmental aspects such as magnetic fields, external electrical influences, electrostatic dischargesdischarge... (...)".
This Directive has been transposedtrasposed by the Royal Degree 1616/2009, of 26 October, for the regulation of active implantable medical devices.
Whenever a pacient livesliving or worksworking near electrical equipment, it is essential to have information from the patient's cardiologist and the manufacturer of the device,as they mustshould be made aware of the level at which interference may occur.
(*) Spanish version.