Link between screen time and inattentiveness cannot be ignored

Yet another study has shown a strong link between screen time and ADHD in children, but we are still no closer to establishing a causal link. But do we even need a causal link?
The new Canadian study of 2,300 kindergarten-age children in Toronto, Winnipeg, Edmonton and Vancouver, indicates that children who spend more than two hours a day staring at screens (of any kind, whether TV, computer, tablet or phone) are over five times more likely to be inattentive, and seven times more likely to show symptoms of attention deficit hyperactivity disorder (ADHD) than children who spend half an hour or less in front of screens.
Granted, the authors are not able to come out and say that the screen time is actually causing the inattentiveness and hyperactivity, due to the difficulty in screening out (no pun intended) other factors. In particular, children who spend less time in front of a screen also tend to be more physically active, which seems to some extent to counteract the effects of screen time.
But it is yet more evidence that less screen time is better than more screen time, and surely we are now at the stage where all this evidence cannot be denied or ignored.

UPDATE
Hard on the heels of that report comes one from the World Health Organization (WHO) which concludes that children under the age of one should not be exposed to ANY electronic screen time at all, and that older children, from two to four, should be limited to just one hour a day. Writing on the wall, or what?