Now this is a repair job from a fella after watching my mother do repairs many moons ago..No don't wear em.....Snip small hole in back where elastic is snip and pull out elastic. Tape the new elastic to a cut down knitting needle or try a plastic drinking straw, about 3 ins long and feed it through nicked hole all way around of course back out of the hole and either sew ends together flat or tie poking tie end back in hole stitch up the hole. Job done. Don't forget to measure elastic around your waste first to a comfortable length, not too tight, not too lose. Mum taught me to be self sufficient which annoys the wife.
BB, March 2011