I remember when I was young in the '70, when there were only two channels on TV and the broadcasts were starting at 5 in summer that I started reading every book I could find... So I can't say that one can read too much. Ok sometimes I preferred to finish a sci-fi book of an obscure author rather than to go to play football outside.
If we talk about medical and scientific article, also I think there's no such thing of too much reading, but if we talk about tabloids and pseusoscientifici claims you find on tabloid and of facebook it's another story.