The Chemical Identity of Red 3
Red 3, more formally known as Erythrosine, is an organoiodine compound and a derivative of fluorone. Its official chemical name is disodium 2-(2,4,5,7-tetraiodo-6-oxido-3-oxoxanthen-9-yl)benzoate. As the name suggests, a critical component of its structure is four iodine atoms attached to a fluorescein molecule. The disodium salt component makes it water-soluble, which is a desirable property for its use as a food coloring. This complex organic compound is manufactured synthetically and is derived from petroleum. The petroleum-based nature and the presence of iodine are two characteristics that have contributed to its long-standing controversy.
The Manufacturing Process of Erythrosine
Red 3 is not a naturally occurring substance but is instead synthesized through a chemical process. This process begins with the condensation of resorcinol and phthalic anhydride to produce fluorescein. The fluorescein is then subjected to iodination, a process where iodine is added to the molecule, which gives the dye its characteristic reddish-pink color. After iodination, it is converted into the disodium salt form, making it water-soluble and suitable for use in a wide range of products. This synthetic production method results in a standardized and consistent colorant, which is why it has been so widely used commercially for decades.
Common Uses Before the Ban
Prior to the FDA's decision to ban Red 3 from food and ingested drugs, it was a common additive in a large number of products. Its vibrant, cherry-red color made it an ideal choice for many food items and medications. A partial list of products that historically contained Red 3 includes:
- Maraschino cherries
- Cakes, cupcakes, frostings, and icings
- Candies, especially those with seasonal or fruity themes
- Frozen desserts like popsicles and ice cream
- Strawberry-flavored milk and other beverages
- Some gummy vitamins and cough syrups
- Processed fish products, hot dogs, and sausages
The dye was also used in other applications, such as a stain for visualizing certain cell types in microscopy and as a dental plaque disclosing agent. However, its use in cosmetics and topically applied drugs was banned by the FDA in 1990 after animal studies linked it to cancer. This created a regulatory paradox that persisted for decades.
Comparison: Red 3 vs. Red 40
With the ban on Red 3, many manufacturers have turned to Red 40 as a replacement. The two dyes, while both petroleum-derived synthetic colorants, have distinct chemical differences and regulatory histories.
| Feature | Red 3 (Erythrosine) | Red 40 (Allura Red) |
|---|---|---|
| Chemical Type | Organoiodine compound, xanthene derivative | Azo dye |
| Key Component | Contains four iodine atoms | Does not contain iodine |
| Health Concerns | Linked to thyroid issues and cancer in animal studies. Concerns about neurobehavioral effects in children. | Concerns regarding hyperactivity and neurobehavioral effects in some children. Some studies suggested a link to accelerated immune-system tumor growth in mice, though Red 40 is not classified as a carcinogen like Red 3. |
| Regulatory Status (U.S.) | FDA ban for food and ingested drugs announced in 2025. Banned in cosmetics since 1990. | Still approved by the FDA for food and drugs. |
| Global Restrictions | Banned or restricted in many countries, including those in the EU, Australia, and New Zealand. | Restrictions and warning label requirements in some countries, including the EU. |
The Health Risks and Regulatory Action
The ban on Red 3 was a culmination of decades of research and advocacy. The primary catalyst was a series of animal studies conducted in the 1980s that showed the dye caused thyroid tumors in male rats at high doses. Although the FDA initially stated the effect was rat-specific and did not apply to humans, the Delaney Clause, a provision of the Federal Food, Drug, and Cosmetic Act, mandates a ban on any food additive found to cause cancer in animals or humans. This led to its ban in cosmetics and topical drugs in 1990, but regulatory inaction allowed its use in food and ingested drugs to continue for over 30 years.
Health advocates, including the Center for Science in the Public Interest (CSPI), continued to press the issue, citing both the cancer link and potential neurobehavioral issues, especially in children. In January 2025, the FDA finally revoked its authorization for Red 3 in food and ingested drugs, citing the Delaney Clause. Manufacturers were given until 2027 and 2028, respectively, to remove the dye from their products.
Alternatives and Consumer Choice
As Red 3 is phased out, consumers can expect to see more natural colorants in their products. Common replacements for synthetic dyes include:
- Beet Juice: Offers a natural red color, used in items like ice cream and fruit pops.
- Carmine: A dye derived from cochineal insects, providing a rich red color.
- Purple Sweet Potato and Red Cabbage Extracts: Plant-based options offering a range of red and purple hues.
For consumers wishing to avoid synthetic dyes, it is best to read ingredient labels and look for the specific name "FD&C Red No. 3" or "Red 3". The move toward natural alternatives aligns with growing consumer preference for cleaner ingredient lists.
Conclusion
In summary, Red 3, or Erythrosine, is a synthetic, petroleum-based dye characterized by its organoiodine chemical composition, C20H6I4Na2O5. The presence of iodine and the results of animal studies linking it to thyroid tumors led to its ban in cosmetics in 1990 and, after decades of delay, its eventual prohibition in food and ingested drugs by the FDA in 2025. The ban highlights the increasing scrutiny of synthetic food additives and the shift towards safer, natural alternatives like beet juice and carmine. Consumers can protect themselves by checking ingredient lists for "FD&C Red No. 3" until the phase-out is complete. For more information on food safety, visit the official Food and Drug Administration website.
