As long as you completely clean off the Borax on the surfaces you clean with and leave no Borax Residue on the surfaces Borax is very safe to clean with.
If you have young children or toddlers who like to lick things then make sure you really clean the Borax off because it could cause problems if digested.
Or better yet if you have young children I would recommend using something more natural and non toxic to clean with instead.