The Royal College of Paediatrics and Child Health (RCPCH) recently published a guidance report investigating any relation between digital screen time and toxic behavior. The consensus: They can't find a connection.
The report covers any screen usage, including but not limited to video games, smart devices, TVs, and other screen-based activities. The institution reports that there is "not enough evidence to confirm that screen time is in itself harmful to child health at any age."
As a result, the RCPCH claims that is it impossible (their word, not ours) to determine what the appropriate amount of screen time would be based on an individual's age. Instead, they recommend basing any restrictions on their developmental stages and the individual in question.
The report also states that this is is in regards to screen usage in general, and not the content displayed on screen. Parents should still be mindful of what exactly they are exposing their children to at young ages. Just because TV is safe doesn't mean your 6-year-old should watch as much South Park as they can handle. They remind parents of the existing systems of determining how child-approved games and programs are.
"It is important that parents are aware of these systems, and mindful of them, especially when older siblings may be playing violent or explicit games."
It's important to not forget about the physical effects screen watching can have, however. The report focuses on the mental effects, but it is based on a separate report that showed that children who view a digital screen 1.5 hours before bed will show signs of less or lower quality sleep.
You can find the full report and a parents' fact sheet at the RCPCH website.