There is anecdotal evidence about problems with pacemakers and electric trains in Belgium and Sweden: the electrification in these countries is at 16-2/3Hz, and thyristor controlled trains running slowly produce quite intense magnetic field bursts. These frequencies are low enough to get picked up on the leads and get into the sensing circuitry. However, my contacts in the pacemaker manufacturers have not yet found any solid evidence.
Shows the advantage of steam.....