I wouldn't worry about it too much. So long as you regularly cycle the water in the bottles with fresh supply you aren't increasing your exposure any over buying new ones filled with liquid that have been sitting on store shelves for weeks, or maybe months. The rate of decay is the same over the life of the bottle, more or less. From the moment they are first created and filled with liquid, they are leaching chemicals. Freezing them likely slows the leaching process down.

I would lay off the bleach. Hot soapy water is probably sufficient, unless you are putting poor quality liquid in them. Don't use detergents in them either.

For long term storage, nothing beats glass or stainless.