The Center for Science in the Public Interest (CSPI) has submitted a letter to U.S. Food and Drug Administration (FDA) Commissioner Robert Califf urging the agency to prohibit retail distribution of highly concentrated caffeine products, including powdered (PPC), liquid and inhaled caffeine.

The recently released letter supplements CSPI’s 2014 citizen petition requesting the ban following the deaths caused by over-ingestion of caffeine powder. FDA sent warning letters to companies selling the substance, but “FDA’s five letters appear to have ceased the sale of powdered caffeine at only the companies to which the agency addressed the letters,” the CSPI document argues. “In the larger marketplace, sales of PPC remain commonplace, and the substance is still widely available. This compelling evidence demonstrates why a ban is the only step that will protect consumers from the hazards of PPC.”