FDA Bans Red Dye No. 4: Tumors End an Era of Unsafe Additives

The FDA banned Red Dye No. 4 on October 22, 1976, after research linked the synthetic food coloring to bladder tumors in laboratory dogs, removing one of the most widely used artificial colorings from the American food supply overnight. The dye, also known as Ponceau SX, had been a staple in maraschino cherries, candy, processed meats, and cosmetics for decades. Its removal came during a broader wave of FDA crackdowns on artificial colorings that included the controversial ban on Red Dye No. 2 earlier that year, a decision that had already shaken the food manufacturing industry. The toxicology evidence against Red Dye No. 4 was stronger than it had been for No. 2: repeated studies showed consistent tumor formation in test animals at dosages that regulators considered relevant to human consumption levels. Canada, however, reached a different conclusion from the same data and continued to permit the dye in its food supply. This regulatory split created an awkward situation for multinational food companies, which were forced to manufacture different formulations for the U.S. and Canadian markets using the same production facilities. Consumer advocacy groups in the United States seized on the ban as evidence that the food industry had been feeding Americans carcinogens for years, and used the momentum to push for stricter labeling requirements on all artificial additives. The campaign contributed to a lasting shift in American consumer attitudes toward processed food ingredients that continues to shape purchasing behavior today.