Is it safe to use old (10+ yrs.) cotton/cotton balls that were stored in bags? Does its chemical consistency change? Also, same for tp, paper towels, dinner napkins?

Unless you need a sterile surgical field, it is safe.

Thank you. Found some old stored tissues which were the purse pack size and they had a terrible chemical smell.

Well, maybe don’t use them to blow your nose but to wash a few windows. I would trust your nose.

If it looks like, smells like, feels like the way it did, I would think there is no difference. And If it is not going to be used on exposed skin or near the sensitive areas, I would use it. I’m guesssing.

If they still have their original properties, I’d use them for their intended purposes.
If they had an odor, I would keep them in the workshop or car for cleaning glass, wiping up messes, cleaning tools, etc.
I would not throw them out simply because they were old.