Like the Romans used to drink from lead cups. Something like that.
(it appears that the moderator is removing any replies with which he disagrees. It might be a piefed issue. But all the removed replies are top level and upopular. Stranger coincidences have happened I suppose.)
That might be true in the short term, but we’ve had books and avid readers for centuries, and during this time we’ve seen positive effects. So if there are any negative effects, they must be so tiny that they’re neither noticeable nor measurable.