The studies are highlighting particular risks for boys and girls at certain ages.
The study, which covers only the spending on local television commercials, also highlights what areas of the country each campaign is trying to reach.
The study also highlighted significant differences among different minority groups.
The study also highlighted the influence of the digital divide on young children.
Another large study has highlighted the potential benefits of alcohol to health and longevity.
Both these studies highlight issues that needed urgent attention from policy and practice.
A recent study has highlighted the importance of this research.
Many previous studies highlight the importance of sleep in cognitive performance.
However, campaigners said the study highlighted the need for more research.
This study also highlighted some differences in the methods of financing.