The U.S. Food and Drug Administration has issued warning letters to five producers of pure powdered caffeine. Consumer groups have been urging this be done due to the very small differences between a safe dose and one that is toxic. Last year two healthy young men died after consuming too much. Caffeine is a powerful stimulant that in its pure form is nearly impossible to accurately measure with common kitchen tools.
PositiveTip: Avoid pure powdered caffeine in all forms!
Reference: http://www.fda.gov/Food/RecallsOutbreaksEmergencies/SafetyAlertsAdvisories/ucm405787.htm