if you don't have one for him maybe you could try a Kong toy. It's a toy you can put a treat or paste in that they have to chew and work at to get the treat out. You'd have to catch him trying to eat things, but a good way to try and train him out of that is to catch him in action, use a noise or a "leave it!" cue, then replace the item with the chew toy.
Definitely can be a life threatening habit if something causes an obstruction.