Evaluation of the inter-person variability of hazards to the users of BAHA hearing implants caused by exposure to a low frequency magnetic field.

PURPOSE: In this work, the inter-person variability of hazards caused by a low frequency magnetic field exposure (of various polarization and homogeneity near to the magneto therapy applicator) to users of bone anchored hearing aid (BAHA) hearing implants were investigated with respect to various head structures.

MATERIAL AND METHODS: The effects of exposure were evaluated by numerical simulations of the electric field (Ein ) induced in head phantoms (regular or with implant model). Phantoms mimic head dimensions and thicknesses of layers of skin, fat, skull bones, and brain.

RESULTS: The values of Ein obtained in the phantom of the BAHA user's head were several times (up to 4.5) higher than in a regular person. The highest differences in Ein values were found in the skin and fat tissues - up to 80% in phantoms of various structures (statistically significant differences related to various tissues thicknesses, not-significant with relation to phantom dimensions - Kruskal-Wallis test with Bonferroni correction, p < .017) and up to 3 times with magnetic field spatial distribution (statistically significant with different polarization).

CONCLUSIONS: The results support the need to assess the electromagnetic fields hazards to individual implant user exposed to the magnetic field at a level approaching the exposure limits set by international guidelines.