I don't think I'd use them for anything other than their intended purpose if you don't know exactly what's in them. For the leaky ones, you could probably collect the gel into some other sealed container like an old jar (not totally filled). Then it would still work well as a cold source for coolers/lunch packs.
I don't think I'd use them for anything other than their intended purpose if you don't know exactly what's in them. For the leaky ones, you could probably collect the gel into some other sealed container like an old jar (not totally filled). Then it would still work well as a cold source for coolers/lunch packs.