Erythrosine

Erythrosine, also known as Red No. 3, is an organoiodine compound, specifically a derivative of fluorone. It is a pink dye which is primarily used for food coloring. It is the disodium salt of 2,4,5,7-tetraiodofluorescein. Its maximum absorbance is at 530 nm in an aqueous solution, and it is subject to photodegradation.

Uses
It is used as a food coloring, printing ink, biological stain, dental plaque disclosing agent, radiopaque medium, sensitizer for orthochromatic photographic films, and visible light photoredox catalyst.

Erythrosine is commonly used in sweets such as some candies and ice pops, and even more widely used in cake-decorating gels. It was also used to color pistachio shells. As a food additive, it has the E number E127.

Regulation and prevalence
Erythrosine is banned as a food additive in the European Union, Japan, China, the United Kingdom, Australia, and New Zealand. Erythrosine can be used in colored food and ingested drugs in the U.S. without any restriction; however, its use is banned in cosmetics and topical drugs. It is less commonly used in the United States because Allura Red AC (Red #40) is generally used instead. The lake variant is also banned from use in the United States.

The European Food Safety Authority only allows erythrosine in processed cherries and pet foods.

United States
As a result of efforts begun in the 1970s, in 1990, the U.S. Food and Drug Administration (FDA) instituted a partial ban on erythrosine, citing research that high doses cause cancer in rats. A 1990 study concluded that "chronic erythrosine ingestion may promote thyroid tumor formation in rats via chronic stimulation of the thyroid by TSH." with 4% of total daily dietary intake consisting of erythrosine B. A series of toxicology tests combined with a review of other reported studies concluded that erythrosine is non-genotoxic and any increase in tumors is caused by a non-genotoxic mechanism.

In June 2008, the Center for Science in the Public Interest (CSPI) petitioned the FDA for a complete ban on erythrosine in the United States, but the FDA has not taken any further action.

As of May 2023, the U.S. state of New York is considering banning the use of Red Dye No. 3 in foods (it was already banned from cosmetics as of 1990) because it has been shown to cause cancer in animals and because of claims that it, and other synthetic food dyes, may contribute to child behavioral problems such as hyperactivity. California plans to ban the manufacture, sale, and distribution of foods containing Red Dye No. 3 starting in 2027, following a bill signed into law in October 2023 that also bans three other food additives: propylparaben, potassium bromate, and brominated vegetable oil.

Synonyms
Erythrosine B; Erythrosin B; Acid Red 51; C.I. 45430; FD&C Red No. 3; E127; 2',4',5',7'-Tetraiodo-3',6'-dihydroxy-spiro[3H-isobenzofuran-1,9'-xanthen]-3-one disodium salt; Tetraiodofluorescein sodium salt; Calcoid Erythrosine N; 2,4,5,7-Tetraiodo-3,6-dihydroxyxanthene-9-spiro-1'-3H-isobenzofuran-3'-one disodium salt; 2',4',5',7'-Tetraiodofluorescein, disodium salt; C.I. Food Red 14; Aizen Erythrosine; Tetraiodifluorescein, disodium salt; Spiro[isobenzofuran- 1(3H),9'-[9H]xanthen]-3-one, 3',6'-dihydroxy-2',4',5',7'-tetraiodo-, disodium salt.

Classification
It is listed under the following number systems:
 * FD&C Red No. 3
 * E number E127 (Food Red 14)
 * Color Index no. 45430 (Acid Red 51)
 * Bureau of Indian Standards No. 1697