"The FDA considers caffeine safe for use in cola-type beverages up to 0.02 percent. The lack of a standard for other products makes its use in those illegal," CSPI wrote in a press memo.
The group is known for its campaigns in favor of soda taxes, trans fat bans and menu labeling — controversial efforts that it make it unpopular with conservatives and the restaurant industry. Republican members of Congress have criticized it for favoring a "nanny-state" approach to fighting obesity.
On Wednesday, CSPI Executive Director Michael F. Jacobson said "serious health problems for children" could come as the result of caffeinated snacks.
In a letter to the agency, he pointed to Cracker Jack'D, MiO water enhancers and "Extreme Sport Beans" from Jelly Belly as snacks that could violate FDA rules.
"Those products may be just the beginning of a craze in which companies, large and small, disregard the FDA's regulation and begin adding caffeine to all kinds of foods and beverages," Jacobson wrote.
Cracker Jack'D is marketed as "cocoa java clusters with energy-packed ingredients" and is expected to hit shelves at the end of the year, according to NationwideCandy.com.
CSPI estimated that each package may contain as much caffeine as a six-ounce cup of coffee.
Cracker Jack'D maker Frito-Lay told CSPI late Wednesday that the snack will not be marketed to children, the group said Thursday.
Each Cracker Jack'D package will contain about 70mg of caffeine, or the amount in a single espresso shot, and no caffeine additives, CSPI said.
—This post was updated Thursday at 12:22 p.m. to reflect Frito-Lay's communication with CSPI.