Electric fields in the human body resulting from 60-hz contact currents

Contact currents occur when a person touches conductive surfaces at differe nt potentials and completes a path for current flow through the body. Such currents provide an additional coupling mechanism to that, due to the direc t field effect between the human body and low-frequency external fields. Th e scalar potential finite difference method, with minor modifications, is a pplied to assess current density and electric field within excitable tissue and bone marrow due to contact current. An anatomically correct adult mode l is used, as well as a proportionally downsized child model. Three pathway s of contact current are modeled: hand to opposite hand and both feet, hand to hand only, and hand to both feet. Because of its larger size relative t o the child, the adult model has lower electric field and current-density v alues in tissues/unit of contact current. For a contact current of 1 mA [th e occupational reference level set by the International Commission on Non-i onizing Protection (ICNIRP)], the current density in brain does not exceed the basic restriction of 10 mA/m(2). The restriction is exceeded slightly i n the spine, and by a factor of more than 2 in the heart. For a contact cur rent of 0.5 mA (ICNIRP general public reference level), the basic restricti on of 2 mA/m(2) is exceeded several-fold in the spine and heart. Several mi croamperes of contact current produces tens of mV/m within the child's lowe r arm bone marrow.