Carbon Black
A synthetic black dye banned from food in the UK and EU since the 1970s. Not permitted in any major food market.
Gut bacteria can break azo dyes into aromatic amines, which animal studies link to genotoxic effects. One long-term rat study found increased mammary tumours in females. No safe intake level has ever been established.
What is it?
Black 7984, also known as Food Black 2 or C.I. 27755, is a brown-to-black synthetic diazo dye. It is a water-soluble tetrasodium salt built from two azo (-N=N-) linkages connecting naphthalene-sulfonated rings. Some secondary sources call it 'carbon black' but that label is inaccurate: true carbon black (a petroleum-derived pigment) carries the separate designation E153 in some historical listings. Black 7984 is an entirely different synthetic organic molecule.
What does it do?
Acts as a deep black food colourant by absorbing visible light across the spectrum. The azo bonds are the colour-carrying chromophores. In the gut, bacterial azoreductases can cleave these bonds to release aromatic amine fragments, the metabolic pathway that raises genotoxicity concerns with azo dyes as a class.
Where you will see it
E152 is not legally permitted in the UK, EU, USA, Australia, Canada, or Japan, so it should not appear in food sold in those markets. Historically it was used to colour beverages, confectionery, and bakery products before its removal from food use in the 1970s. Its current permitted uses are limited to cosmetics (excluding hair dyes) and inkjet printing inks under EU cosmetics regulation. A UK label listing 'E152' or 'Black 7984' in a food product would indicate a non-compliant product.
What the science says
JECFA withdrew approval: no safe level could be set
The Joint FAO/WHO Expert Committee on Food Additives evaluated Black 7984 in 1977 and declined to allocate an Acceptable Daily Intake, citing insufficient toxicological data to establish safety. Specifications were formally withdrawn in 1984. Without an ADI, the additive had no internationally recognised safe use level.
JECFA allocated no ADI for Black 7984 (Food Black 2). Specifications were withdrawn in 1984 due to inadequate toxicological data.
Animal studies: conflicting tumour findings
Rat feeding studies gave mixed results. In one long-term study, rats receiving the dye in drinking water showed no abnormalities in growth, survival, or tissue pathology for over 500 days. A separate study reported increased male mortality and mammary tumours in female rats. The conflicting findings, combined with thin data overall, were a key reason regulators could not establish a safe level.
Long-term rat study (543+ days, 0.5% in drinking water) found no abnormalities in growth, survival, or histopathology.
A separate long-term rat study reported increased male mortality and mammary tumours in females; no subcutaneous tumours were found in another subcutaneous-dose study despite high serum-protein binding.
Azo dye class concern: gut bacteria release potentially genotoxic amines
Azo dyes as a class are reduced by intestinal bacteria to aromatic amines. Those amines can then be activated by liver enzymes into reactive compounds that bind to DNA. This mechanism has been demonstrated for multiple azo food dyes in laboratory and animal models, and is the reason that an azo dye's metabolic breakdown products are scrutinised as carefully as the parent molecule. Whether Black 7984's specific aromatic amine breakdown products are genotoxic at food-relevant exposures has not been established, because the dye was withdrawn before detailed modern genotoxicity testing was completed.
Azo dyes are metabolised by intestinal microflora via azoreductase enzymes to aromatic amines, which mammalian microsomal enzymes can further activate to genotoxic compounds capable of binding DNA.
Black 7984 showed rapid reductive splitting of its azo linkages following intravenous injection in dogs, with metabolites excreted in urine; gastrointestinal absorption of the intact dye was poor.
EU removal: deleted from the positive list by the Scientific Committee on Food
Black 7984 was one of several artificial colours removed from the EU positive list when it was revised. The European Commission's Scientific Committee on Food reviewed new toxicological data and deleted the dye from the permitted list, removing its food authorisation at the end of 1976. It has not been permitted in EU food at any point since.
E152 was approved under EU Directive 62/2645/EEC as a food colorant until end of 1976. The Scientific Committee on Food reviewed new toxicological data and deleted it from the positive list of colours; it has not been re-authorised.
Where it stands with the regulators
Who should be careful
E152 is not a permitted food additive in the UK, EU, USA, Canada, Australia, or Japan, so it should not be present in any compliant food product. If you see 'E152' or 'Black 7984' on a UK food label, the product is non-compliant with food law and should be reported to the Food Standards Agency.
The honest read
E152 is not a current food additive controversy: it was removed from food use before most people alive today were born. The relevant question is not whether to consume it but whether it appears on a label at all, which would signal a non-compliant product. The reason it was banned was insufficient evidence to set a safe level, compounded by conflicting animal data including a study that found mammary tumours in female rats. Azo dyes as a class are metabolised by gut bacteria into aromatic amines, a pathway that carries well-documented genotoxic potential for some members of the family. Whether Black 7984's specific metabolites are harmful at the doses that would have come from food has never been resolved, because the dye was withdrawn before that work was done. The honest position is: regulators could not confirm it was acceptable, the data were insufficient and in places contradictory, and the dye was dropped.
Related additives
Common questions
Is E152 banned in the UK?
Yes. E152 (Black 7984) is not listed in the UK FSA Register of Food Additive Authorisations. It was removed from the EU positive list for food colours at the end of 1976 and has not been re-authorised. The UK, having retained EU food additive law, does not permit it in food.
Why was E152 removed from the permitted colours list?
The Scientific Committee on Food reviewed new toxicological data in the mid-1970s and removed Black 7984 from the positive list. JECFA then evaluated it in 1977 and could not allocate an Acceptable Daily Intake because the available data were insufficient and contradictory. One long-term rat study showed increased mammary tumours in females; another showed no adverse effects. Specifications were formally withdrawn in 1984.
What foods contain E152?
No food legally sold in the UK, EU, USA, Canada, Australia, or Japan should contain E152. It was historically used in beverages, confectionery, and bakery products before its removal in the 1970s. Its only current permitted uses are in cosmetics (not hair dyes) and printing inks.
Is E152 vegan?
Black 7984 is a synthetic dye with no animal-derived ingredients in its production. However, the relevant concern for consumers is that it is not legally permitted in food at all, not whether it is vegan.
Sources
- JECFA Monograph 434: Black 7984 (WHO Food Additives Series 12)
- WHO JECFA database: Black 7984 (Chemical 1105) - No ADI allocated, specifications withdrawn 1984
- Black 7984 - Wikipedia
- UK FSA Register of Food Additive Authorisations (E152 absent; E151 and E153 present)
- FSA Approved Additives and E Numbers
- NATCOL Foods Colors Legislation - full article (deletion from EU positive list history)
- Azo dyes degradation by microorganisms - PMC review (azo reduction to aromatic amines pathway)
- EU Cosmetics Regulation (EC) No 1223/2009 - current permitted use of Black 7984 in cosmetics
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