Federal Register notice was dry. It stated that the color additive FD&C Red No. 4, a common ingredient in maraschino cherries, certain drugs, and cosmetics, could no longer be used. The decision rested on a two-year rat study and a more definitive seventy-eight-week dog study. In those beagles, high doses of the dye produced a statistically significant increase in benign and malignant tumors of the urinary bladder. The Delaney Clause, a 1958 amendment to the Food, Drug, and Cosmetic Act, mandated an automatic ban on any additive shown to induce cancer in humans or animals. There was no room for risk assessment.
The ban highlighted the crude but powerful tool of mid-century food safety law. Scientists debated the relevance of the dog models, noting the doses were extremely high and the mechanism unclear. Critics of regulation argued it was an overreach; public health advocates saw it as a necessary application of a precautionary principle. The dye was already partially restricted, having been removed from externally applied cosmetics and ingested drugs in 1964. This final action removed it from all food.
Red Dye No. 4 was largely replaced by Red Dye No. 40, which remains in use today. The event underscored the central, if controversial, role of animal toxicology in public health policy. It also illustrated the legal rigidity of the Delaney Clause, which would later be modified to allow for de minimis risk considerations. The health of a group of laboratory beagles directly altered the composition of the American food supply.