What are the health risks for children who drink all those "energy drinks "on a regular basis?

Depends on the drink: Thankfully most of the vitamin material in energy drinks goes thru you like water. They are not stored & if not used for something they are gone the same day. My primary concern are the drinks with high caffeine & sugar content which can influence blood pressure and weight gain.

Nobody knows: Since these products are considered food supplements, there is no requirement for safety testing. There have been a number of deaths reported to the fda in teenagers using these products, and there is an fda investigation which has been started. Many of these products do not even list the amount of caffeine they contain. Some have about 1/2 the amount of caffeine as a cup of coffee, others more.