Washable, Wearable Tech with Arduino
I would use some sort of epoxy and cover up the exposed circuitry. The major concern would be where the wires connect to the board as flex over time can weaken it.

Some options include:


3M™ Scotchcast™ Wet-Niche Potting Kit
Hysol


  US1150™—For electronics, telecommunications, and automotive
  components. Provides environmental hazard protection.
  
  US1152™—For electronic assemblies. Provides environmental hazard protection.
  
  Heat might play a factor if you cover up the boards in epoxy but you shouldn't be producing that much heat in a wearable device anyway, right?