Cleaning with rubbing alcohol and salt is perfectly safe. I used to clean my friends glass bong with this method all the time, often using an entire bottle of the shit. (It's a big bong) You just have to rinse it out after to get any remaining salt out and isopropyl alcohol evaporates quickly. This is the best method I know of for getting smoking devices 100% clean.
Unless you want to spring some extra cash from something like Formula 420 or Orange Chronic Cleaner, not sure what those contain.