On behalf of the Federal Institute of Occupational Safety and Health (BAuA), Berlin IMST GmbH has developed a numerical tool for the calculation of the interference voltage at the input impedance of cardiac pacemakers in the frequency range from 10 Hz to 1 MHz. The numerical tool takes into account a model of a unipolar electrode, a realistic position of the implant in the human body and a realistic model of the exposure scenario. The method has been applied to homogeneous magnetic and electric field exposure in order to get worst case estimations for practical applications and regulatory purposes. The numerical method can be transferred to other implants that use measurement or stimulation electrodes. The numerical method improves the evaluation of the safety of workers with implants in workplace with high electric, magnetic or electromagnetic fields. In individual cases a more accurate risk evaluation is possible. This project forms the basis for future investigations of real workplaces where inhomogeneous fields will be considered.