A modern ANR headset is a signal processing solution and requires no change to the transducers in your headset except perhaps for an additional microphone. I very much doubt there is any danger from the E and B fields from the small low power moving coils in a modern headset.
Few if any crew use ANR any way as all modern aircraft have both passive and active acoustic cancellation and damping in the cockpit. Having said that they may be useful if you spend your days flying SEP/MEP or rotary wing.
Last edited by Fostex; 14th Feb 2012 at 11:02.