The American Academy of Pediatrics just came out with new recommendations for use of electronic devices for young children. Prior to this time they did not recommend that children under 2 have any use of these devices and very limited access for preschoolers, but they have made some significant changes to their recommendations that I believe are important for librarians to be aware of. They highlight the need for parents to develop a plan for how they want their children to use electronic media, to choose high-quality educational programming and apps, and to use them together with their children. [And it specifically recommends materials from PBS KIDS and Sesame Street J]
Here is a link to the full article including some very easy to understand recommendations for pediatricians and families:
http://pediatrics.aappublications.org/content/early/2016/10/19/peds.2016-2591