The company, based in Corona, Calif., says it's being unfairly singled out by City Attorney Dennis Herrera, who late last year had asked Monster to produce documentation showing that its drinks are safe. Since then, Monster says Herrera has asked it to reformulate its drinks and change its labels and marketing materials.
A representative for the city attorney's office, Matt Dorsey, said "we're aware of the lawsuit and the city attorney is evaluating his options."
The suit comes at a time when the energy drink industry has come under intense scrutiny. The Food and Drug Administration is investigating reports of deaths linked to energy drinks, although the agency has noted that the reports don't prove the drinks caused the deaths.
New York's attorney general has also subpoenaed Monster -- as well as the maker of 5-Hour Energy shots and PepsiCo Inc., which makes Amp -- as part of an investigation into how energy drinks are made and marketed. In addition, the family of a 14-year-old girl is suing Monster after they said she died after drinking two 24-ounce cans of Monster in a short period.
Monster meanwhile has stood by the safety of its drinks. Earlier this year, the company hit back at the lawsuit, noting that there was no blood test performed to confirm that the girl died of caffeine toxicity.
In its lawsuit against San Francisco's city attorney, Monster Beverage Corp. cites a letter from Herrera dated March 29 asking the company to reformulate its product to "lower the caffeine content to safe levels" and to provide "adequate warning labels".
Monster's current label says people should limit themselves to one can every four hours and a maximum of three per day. It also says the drink isn't recommended for children, people sensitive to caffeine, pregnant women or women who are nursing.
But the city attorney said in his letter that three cans amount to 480 milligrams of caffeine, nearly five times the recommended maximum for adolescents and more than the 400 milligrams per day the FDA has indicated is safe for adults.
Although some brands of coffee contain more caffeine than Monster's energy drinks, Herrera also said that coffee is typically served hot and consumed slowly. Energy drink makers, by contrast, specifically market to youth and encourage them to "pound down" their drinks in large quantities, the letter said.
Even as soda consumption has flagged in recent years, energy drinks including Red Bull and Rockstar have surged in popularity. In 2011, sales volume for energy drinks rose by nearly 17 percent, according to Beverage Digest, an industry tracker.
Caffeine is also turning up in other foods, including jelly beans, waffles and Frito-Lay's Cracker Jack'd, which are coated wafers that include two tablespoons of ground coffee. On Monday, the FDA said it would investigate the safety of added caffeine and its effect on children and adolescents.
The investigation was prompted by the introduction of a caffeinated gum by Wrigley that has as much caffeine as a half a cup of coffee in one piece.
The FDA noted the only time it explicitly approved the added use of caffeine in a food or drink was in the 1950s for colas.
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