Fields and current densities induced in the human body by low-frequency electromagnetic fields

Up to now, there seems to be a confusion concerning the description of the interaction of matter with an external electromagnetic field or with extraneous (injected) charges. In this paper we show that an electromagnetic field interacting with matter must be described by four vector fields (E, H, B
_e
and B
_m
). For non-magnetic matter only three fields are necessary (E, B
_m
and B
_e
). The field Be has two parts: the first is the displacement D, which is locally proportional to E; and the second is M
_efr
, which represents the existence of free electric carriers within the matter. For time-harmonic low-frequency fields, if σ/ωε >> 1, B
_e
is dominated by M
_efr
, which depends on the history of E. Then, inside the human body, B
_e
is locally proportional to E delayed by 90 degrees. In the case of a polarized external field, this delay has the consequence that, at the points inside the human body, at a certain time instant, E and B
_e
do not even have the same direction.