W hy are there strict limits imposed by national and international regulations on human
exposure to low frequency magnetic fields?
To date, regulations on human exposure to low frequency magnetic field are based only on acute
effects (short-term effects). The limits imposed are quite high since severe effects, the only ones to
be known with absolute certainty, appears when the intensity of magnetic fields is high.
H ow are safety standards on human exposure to low frequency magnetic fields defined?
Safety standards on human exposure to low frequency magnetic fields are defined according to:
– health effects due to exposure.
– minimum value of intensity of a magnetic field causing harmful effects.
– identification of a safety margin that considers all possible uncertainties in order to identify a limit
of exposure for those workers who are exposed to magnetic fields due to professional reasons.
– identification of a further safety margin to protect the population. This indication is important in
order to protect the most vulnerable population groups such as babies, children, the elderly and the
The identification of this margin takes into account the maximum length of exposure too (24 hours
a day) since it can be of course longer than the exposure of workers.
W/span> hat is the point of having safety standards on human exposure to low frequency magnetic fields?
Safety standards were defined in order to protect human health against possible harmful effects caused by exposure to low frequency magnetic fields, both in the case of professional exposure and non-professional exposure (such as the population and those who are not exposed due to the
specific features of their job).
W hat is the ALARA Principle (“As Low As Reasonably Achievable”)?
ALARA Principle is a radiation physics policy which establish to minimize the known risks due to the exposure to low frequency magnetic fields to the lowest levels reasonably possible, taking into account socio-economic costs and benefits.
That is to say that the less we need a guilty element (such as low frequency magnetic radiations) the most the exposure limit should tend to zero.
When dealing with low frequency magnetic induction it is impossible to completely delete the guilty element, due to its unique usefulness nowadays. Thus the limit of exposure must be carefully identified studying the correlation between its social cost and the limits imposed by regulations.
ALARA Principle is conceptually unobjectionable but it is difficult to be applied in real life situations.
Nevertheless it suggests that those exposures to magnetic fields which are not strictly necessary must be avoided and in any case levels of exposure, due to their dangerousness, must be reduced to the lowest levels possible compatibly with their many applications in modern life.
What does a low frequency magnetic field cause when it passes through human body?
It is important to highlight that the biological tissues and internal organs of human body are affected by electric conductibility, permittivity and magnetic permeability.
When low frequency magnetic induction passes through a biological tissue it causes an electric distortion in its normal molecular balance since low frequency fields generates electric fields andcurrents which stimulate excitable cells such as neurons and muscle cells.
Low frequency magnetic fields generate currents inside biological tissues that moves through the human body affecting internal organs too and preferring the paths were they can find less resistance, namely highly conductive tissues, those currents are then grounded to Earth through the soles of feet.