Cellophane are stable provided they don't get exposed to sunlight. ie UV ray.
Lifespan about 10-15years.
All plastics do have lifespan. The old one that aging fast will starts to change colours ( discolorisation ).
Bank coins bags, they will start to turn colour and the contain ie coins will get effected during the process.
PVC plastic when they age , they will go hard, also start to yellow.
They are not friendly to many metals. Make those copper go green and powdery.
PVC do smell abit when they are new. That how you tell them.
Do burn and create black smoke.