"Magnetic Clasps should not be used around Pacemakers." I wonder just how strong the magnetic field need be to interfere. My dad wore a pacemaker and the primary warning was for microwaves.
My mother has a pacemaker. It has a magnetic switch. A magnet is
placed over the pacemaker to switch it into a different modes of
operation. The magnet is nothing special. I would not be surprised if
one of a magnetic clasp would trigger the switch.