also: FD&C Green No. 3 · Food Green 3 · CI 42053 · Green 1724
A synthetic petroleum-derived green dye, not permitted in UK or EU food. Approved in the US only. Rarely encountered on UK shelves.
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Animal studies found equivocal evidence of bladder tumour signals at high oral doses and injection-site sarcomas in rats.
Why it’s worth knowing. Animal studies found equivocal evidence of bladder tumour signals at high oral doses and injection-site sarcomas in rats. The EU and UK chose not to authorise it when drawing up their positive lists of permitted colours. Any UK product listing it is non-compliant. It is not on the UK list of approved food additives, so you will not normally see this E number on a UK label.
Fast Green FCF is a synthetic triarylmethane dye produced from petroleum-derived hydrocarbons. It is a disodium salt that appears as a red-to-brown-violet powder which produces a blue-green to teal colour in solution. Also known as FD&C Green No. 3 in the United States and Food Green 3.
The dye molecule absorbs light at around 625 nm, producing a visible green-blue colour. It is water-soluble and relatively stable to light and heat compared with some other synthetic dyes. In the body it is poorly absorbed from the gut, which limits systemic uptake.
Not found in UK or EU food products, as it is not authorised here. In the United States, where it remains approved, it has historically appeared in tinned peas, mint ice cream, confectionery, and some beverage mixes. On US labels it reads 'FD&C Green No. 3'. On a UK label, any listing of 'E143' or 'Fast Green FCF' indicates a non-compliant product.
An oral carcinogenicity study in rats found an increased number of bladder epithelial changes and a small number of bladder tumours in the highest-dose male group compared with controls. The results were judged equivocal by the JECFA committee at the time, partly because the numbers were small and the biological significance was unclear. A later histological re-examination found only three proliferative bladder lesions in high-dose males, leading JECFA to conclude there was no clear neoplastic effect.
An oral rat study showed an increased incidence of urothelial hyperplasia in treated males and a small number of bladder transitional-cell neoplasms in the highest-dose group. JECFA initially set only a temporary ADI pending full histological review.
On histological re-examination, only three proliferative bladder lesions were found in high-dose male rats, and JECFA concluded there was no clear indication of a neoplastic effect on the urinary bladder. A permanent ADI of 0-25 mg/kg body weight was then set.
When Fast Green FCF was injected repeatedly under the skin of rats in laboratory studies, fibrosarcomas developed at the injection sites. IARC reviewed this evidence in 1978 (Volume 16) and re-evaluated it in Supplement 7 (1987), assigning IARC Group 3 on both occasions, meaning the evidence was insufficient to classify the substance as a human carcinogen. The JECFA committee separately concluded that injection-site tumours do not constitute evidence of carcinogenicity by the oral route, the route relevant to food.
Fast Green FCF was carcinogenic in rats, producing sarcomas at the site of repeated subcutaneous injections. No human epidemiological data were available to the Working Group. IARC assigned Group 3: not classifiable as to carcinogenicity in humans. This classification was re-confirmed in Supplement 7 (1987).
A 2025 laboratory study exposed zebrafish to Fast Green FCF at concentrations of 0.1%, 0.3% and 0.5% over a prolonged period. Chronic exposure arrested follicular maturation, leaving immature follicles, and reduced acetylcholinesterase activity in the nervous system while increasing markers of oxidative stress. The researchers concluded the dye showed follicular and neural toxicity in this model. Zebrafish studies are an early-stage screening tool and cannot be directly translated to human dietary exposure levels.
Chronic exposure of zebrafish to Fast Green FCF arrested follicular maturation, reduced acetylcholinesterase activity, and increased malondialdehyde levels, indicating oxidative stress and effects on nervous system signalling and reproductive development.
At its 84th meeting in 2017, JECFA reviewed newly available data on Fast Green FCF and reconfirmed the ADI of 0-25 mg/kg body weight. The committee concluded that dietary exposures in all population groups, including the highest adolescent estimate of around 12 mg/kg body weight per day, remain below the ADI and do not present a health concern. The committee noted this ADI applies to countries where the dye is permitted, such as the United States.
JECFA confirmed an ADI of 0-25 mg/kg body weight for Fast Green FCF. New data gave no reason to revise the earlier ADI, and estimated dietary exposures, including the highest adolescent estimate of 12 mg/kg body weight per day, remained below the ADI.
Anyone in the UK who encounters a food listing E143 or Fast Green FCF should know the product is non-compliant with UK food law and may be an illegal import. People who wish to avoid synthetic petroleum-derived dyes can check US-imported products for 'FD&C Green No. 3' on the label.
The science on Fast Green FCF is settled in one direction: it is not authorised in the UK or EU, and has not been for decades. The historical concern that drove this, a small and equivocal bladder tumour signal in rats at high doses, was later re-examined by JECFA and found not to constitute a clear carcinogenic effect. A 2025 zebrafish study adds a newer reproductive and neural toxicity signal, though zebrafish studies at high concentrations are an early indicator, not proof of human harm at real-world exposures. The practical point for a UK shopper is straightforward: this dye has no business being in a UK food product. Any food carrying E143 or Fast Green FCF on a UK shelf is not legally compliant.
Yes. E143 (Fast Green FCF) is not an authorised food additive in the UK. It does not appear on the FSA's approved-additives list or in the UK's assimilated version of EU Regulation 1333/2008. Any food product sold in the UK that contains it is non-compliant with UK food law.
When the EU established its positive list of permitted food colours, Fast Green FCF was not included. The historical background includes an equivocal bladder tumour signal in rats from 1980s studies and injection-site sarcomas noted by IARC in 1978. Although JECFA later confirmed no clear carcinogenic effect at the oral route and reconfirmed the ADI in 2017 (most recently), neither the EU nor the UK has revisited its absence from the positive list.
No legally sold UK food should contain E143. In the United States, where it remains approved, FD&C Green No. 3 has historically appeared in tinned peas, mint-flavoured ice cream, confectionery, and some beverage mixes, though it is the least-used of the seven US-certified food dyes.
Fast Green FCF is a fully synthetic dye derived from petroleum hydrocarbons and contains no animal-derived ingredients. It is vegan in origin. However, as it is not authorised in UK food, the practical question of vegan suitability does not arise for UK products.
Last reviewed: 20 June 2026
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