Which are the safest cartoon series for 4-6 yr olds? i was horrified by violence and foul language shown in some.

Usually, the cartoons and tv shows broadcasted on channels that are catered specifically for children are "safe" to watch, for example Nick Jr (Nickelodeon for younger children) and Okto. If you have Netflix, they have an entire collection of shows specifically for young children for you to choose from. One of my favourites cartoons in that collection is The Winx Club -- it promotes friendship and teamwork. I'd avoid "cartoons" like The Simpsons, South Park, Family Guy and Happy Tree Friends and American Dad. They are definitely not child friendly.