The U.S. Food and Drug Administration said Friday it is issuing new guidelines on dietary supplements that contain high levels of concentrated or pure caffeine. “These products present a significant public health threat because of the high risk that they will be erroneously used at excessive, potentially dangerous doses,” the regulator said in a statement. “Highly concentrated and pure caffeine, often sold in bulk packages, have been linked to at least two deaths in otherwise healthy individuals.” The new guidelines, which are effectively immediately, will remove bulk packages of highly concentrated forms of caffeine. A half cup of a highly concentrated liquid caffeine can have about 2,000 mg of caffeine, but a singly teaspoon of bulk packaged powdered product can have up to 3,200 mg, equal to 20 to 28 cups of coffee, which is a fatal dose. “Regardless of whether the product contains a warning label, such products present a significant and unreasonable risk of illness or injury to the consumer,” said the statement.