Indanthrene blue RS
A synthetic blue pigment originally developed as a textile dye. Withdrawn from food use globally after regulators concluded the safety evidence was inadequate.
Regulators withdrew approval specifically because no data on how the body processes it, and no reproductive or developmental toxicity testing, was ever submitted. The long-term animal studies conducted were judged inadequate. Its legal status in UK and EU food is: not permitted.
What is it?
Indanthrene blue RS is a dark blue synthetic pigment belonging to the anthraquinone class of vat dyes. It is made by heating 2-aminoanthraquinone with potassium hydroxide at high temperature, forming a fused polycyclic ring structure. CAS number 81-77-6 (also listed as 50926-10-8 in some databases), also known as CI Vat Blue 4, CI 69800, Pigment Blue 60, and Indanthrone Blue. It was first synthesised by Rene Bohn at BASF in 1901 as the world's first anthraquinone vat dye.
What does it do?
As a colour additive, it was intended to give an intense, stable blue hue to foods. Its polycyclic aromatic structure makes it exceptionally resistant to fading, heat, and light. In textile dyeing it works as a vat dye: the insoluble pigment is chemically reduced to a soluble form that penetrates fibres, then re-oxidised to lock in the colour. It is practically insoluble in water and in common organic solvents.
Where you will see it
E130 is not legally permitted in UK or EU foods and should not appear in any UK food product. Historically it was proposed for use in confectionery, beverages, and frozen desserts requiring an intense blue colour, but it was never authorised for widespread food use in Europe and was withdrawn from the international positive list before modern food labelling conventions were standardised. On a UK or EU label, you would not legitimately see 'E130' or 'Indanthrene blue RS' listed as an ingredient.
What the science says
Why the safety approval was withdrawn
JECFA, the joint FAO/WHO expert committee on food additives, evaluated indanthrene blue RS multiple times between 1959 and 1974. A temporary acceptable daily intake of 0-1 mg per kilogram of body weight was set in 1969, conditional on additional data being provided. The required information, covering how the dye is metabolised in the body and its effects on reproduction, embryonic development, and foetal harm, was never submitted by the 1974 deadline. JECFA consequently withdrew the temporary ADI. The JECFA specifications for the substance were formally withdrawn in 1984.
JECFA set a temporary ADI of 0-1 mg/kg body weight in 1969 and required data on metabolism and reproductive toxicity to be submitted by 1974. No data was provided and the temporary ADI was withdrawn.
The available long-term rat studies were judged inadequate because only selected parameters were examined. There was no information on metabolism, reproductive toxicity, embryotoxicity, or teratogenicity.
JECFA specifications for indanthrene blue RS were formally withdrawn in 1984.
Animal studies conducted before withdrawal
Rat studies lasting up to two years at dietary concentrations of 0.1% and 1% of feed found no increased tumour incidence and no changes attributed to the test diet. Acute oral toxicity in rats showed an LD50 of 2000 mg/kg. Guinea pig sensitisation tests found no sensitising activity. These results were not sufficient to establish a permanent ADI because metabolism data and reproductive toxicity studies were absent entirely.
Rats fed indanthrene blue RS at 0.1% and 1% of diet for up to two years showed no increased tumour incidence and no changes attributable to the test diet. The studies were judged inadequate due to limited parameters examined.
Oral LD50 in rats was 2000 mg/kg body weight. No sensitising activity was found in guinea pigs.
Removed from the EU food colours positive list
When the European Union replaced its 1962 food colours directive with Directive 94/36/EC, Anthraquinone Blue (another name for this substance) was among seven artificial colours explicitly deleted from the permitted list. The deletion was based on the Scientific Committee on Food's ongoing evaluation of toxicological data. E130 has not appeared in any subsequent EU food additives legislation, including Regulation (EC) 1333/2008, which is the current framework retained in UK law as assimilated legislation.
Seven artificial colours including Anthraquinone Blue were deleted from the EU food colours positive list when Directive 94/36/EC replaced the 1962 directive, based on SCF toxicological evaluations.
E130 does not appear in Annex II of EU Regulation (EC) 1333/2008 or in the UK FSA approved additives list. The sequence in the FSA list runs directly from E129 to E131 with no E130 entry.
Anthraquinone dyes as a class: variable genotoxicity profile
Indanthrene blue RS belongs to the anthraquinone family of dyes, some members of which have shown genotoxic and mutagenic activity in laboratory tests. However, indanthrene blue RS itself (Vat Blue 4) could not be evaluated for genotoxicity in a key mouse lymphoma assay study because it is insoluble in cell culture medium. No IARC carcinogen classification exists for indanthrene blue RS specifically. The class-level concern is real but the compound-specific evidence for this particular dye is absent rather than negative.
In a mouse lymphoma assay of 16 anthraquinone dyes, Vat Blue 4 (indanthrene blue RS) could not be evaluated due to insolubility in the culture medium. Several other anthraquinone dyes in the same study showed mutagenic activity.
Where it stands with the regulators
Who should be careful
No one in the UK or EU should be exposed to E130 through food, as it is not a legal food ingredient. If you see 'E130' or 'Indanthrene blue RS' on a UK food label, that product may not comply with food law. Consumers with concerns should report it to the Food Standards Agency.
The honest read
E130 is unusual among E-numbers in that it was never properly approved for food use and was formally withdrawn from international food safety frameworks in the 1970s and 1980s. The core problem is not that it was proven harmful, but that the companies seeking approval failed to provide the basic safety data, covering metabolism and reproductive effects, that regulators required. Without that data, no ADI could be set and no approval could stand. The EU then deleted it from its colour list in 1994. There is no active scientific debate about reinstating it. The substance's primary role today is as an industrial pigment in textiles, paints, and coatings.
Related additives
Common questions
Is E130 banned in the UK?
E130 is not a permitted food additive in the UK. It is absent from the UK FSA's approved additives list and from the assimilated EU food additives regulation retained in UK law. It was removed from the EU food colours positive list in 1994 and has never been re-authorised. Using it as a food ingredient in the UK would not comply with food law.
Why was E130's food approval withdrawn?
The international food safety body JECFA gave a temporary conditional approval in 1969, requiring the manufacturer to submit data on how the body metabolises the dye and its effects on reproduction and foetal development. That data was never provided. JECFA withdrew the temporary approval in 1974 and formally cancelled the specifications in 1984. The EU then removed Anthraquinone Blue from its positive list when it updated its food colour rules in 1994.
What foods contain E130?
No UK or EU food products should legally contain E130. It is not a permitted food colour in the UK or EU. The dye is used industrially in textile dyeing and in paints and coatings. If any food product listed E130 in the UK, it would not comply with food additive law.
Is E130 vegan?
Indanthrene blue RS is a synthetic chemical with no animal-derived ingredients in its production process. However, the question is largely academic: it is not a permitted food additive in the UK or EU and should not be found in any food product on UK shelves.
Sources
- JECFA monograph 374: Indanthrene blue RS, WHO Food Additives Series 6
- JECFA Evaluations: Indanthrene Blue RS (EEC Serial No. E130), WHO/FAO database
- WHO/FAO JECFA database entry for Indanthrene Blue RS (Chemical 1330)
- UK Food Standards Agency: Approved additives and E numbers
- EU Regulation (EC) No 1333/2008 on food additives
- European Parliament and Council Directive 94/36/EC on colours for use in foodstuffs
- NATCOL: Foods Colors Legislation (full article) - reference to colours deleted in Directive 94/36/EC
- Indanthrone blue, Wikipedia
- Zeiger et al., Analysis of genotoxicity of anthraquinone dyes in mouse lymphoma assay, PubMed PMID 2038271
- Biodegradation of Indanthrene Blue RS dye (textile context), PMC8238989
- IARC Monographs: List of Classifications
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