Griffiths, who has been studying caffeine for more than two decades, said caffeine intoxication can, in rare cases, lead to death. His article is a review paper that compiles studies, reports and surveys on caffeine intake, chemical dependency and energy drinks from numerous sources. The article mentions cases of adverse reactions from caffeine in energy drinks reported to U.S. poison control centers.
"I'm not concerned about someone whose caffeinated beverage of choice is Red Bull - they really are no different than a coffee drinker at that point," he said. "But it's the sporadic use to people who are not tolerant and who are naive and vulnerable in other ways that make it problematic."
Griffiths notes that caffeine stimulant pills such as NoDoz, which contains between 100 and 200 milligrams of caffeine, include a warning on the label saying that too much caffeine may cause nervousness and irritability and that they should not be taken by children under 12.
An FDA spokeswoman said the federal agency has not had time to review the article and could not comment on its claims.
A spokeswoman with Red Bull's U.S. headquarters in Santa Monica said the company is "confident in the safety" of its product and notes that the FDA does not require the caffeine amount to be listed on the drink's label.
Stevens, the beverage association spokesman, noted that the "mainstream" energy drinks that his organization represents have about half the caffeine content found in an average serving of coffee. A 12- ounce cup of coffee contains about 200 milligrams of caffeine. An 8.3-ounce can of Red Bull has 80 milligrams.
"So those suggesting that energy drinks should require warning labels should be aware of the slippery slope this would create," he said. "To be consistent, products at coffeehouses also would require such unnecessary labeling."
Maureen Storey, senior vice president for science policy for the beverage group, said caffeine in such doses is safe.
Stephen Shorofsky, a professor of medicine at the University of Maryland Medical Center, said he thinks energy drinks are "generally safe," except for people with erratic heartbeats, or arrhythmias.
"Anything can cause toxicity," said Shorofsky, director of the electrophysiology laboratory at the medical center. "Is it safe to have caffeine? Sure it's safe to have caffeine. But can you get to a point, where you can cause harmful effects to yourself? Sure."
Still, Griffiths maintains that the burgeoning energy drink industry is a marketing machine whose products are different from a morning cup of coffee - and potentially dangerous.
Since the launch of Red Bull in Austria in 1987 and in the United States a decade later, the market for caffeinated energy beverages has expanded worldwide and accounts for a $5.4 billion industry, Griffiths said.
With names like Amp Energy, Rock Star, and No Fear, the products sell not only a beverage, but a high-energy lifestyle, with claims to expand strength, endurance and toughness. Red Bull says it can "improve vigilance," and the company sponsors competitions in extreme sports and motor cross.
