What is it?
Biphenyl (also called diphenyl) is a white crystalline aromatic compound made of two benzene rings joined together. It is synthesised from benzene and was used as an antifungal preservative applied to the surface of citrus fruits.
E-numbers / Preservatives / E230
Biphenyl
also: Diphenyl · 1,1'-biphenyl · Phenylbenzene
A synthetic antifungal once applied to citrus peel during storage. No longer a permitted food additive in the UK or EU.
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E230
Biphenyl
Animal studies link biphenyl to kidney damage and bladder tumours in male rats at high doses.
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What biphenyl is, what it does and where you will see it
Why it’s worth knowing. Animal studies link biphenyl to kidney damage and bladder tumours in male rats at high doses. The US EPA sets a low reference dose based on dose-related kidney injury in long-term animal studies.
What does it do?
Biphenyl inhibits the growth of Penicillium mould and other fungi on the outer peel of citrus fruit during long-distance transport and cold storage. It was applied as a liquid dip or incorporated into wax coatings on the fruit surface.
Where you will see it
Historically used on the peel of oranges, lemons, grapefruits, mandarins, and limes. It is no longer permitted as a food additive in the UK or EU. Citrus fruit sold in those markets cannot legally carry it. On a label it would have appeared as 'E230', 'biphenyl', or 'diphenyl' in a 'surface treatment' declaration.
What the science says
Kidney damage in animal studies
Long-term feeding studies in rats produced consistent, dose-related damage to the kidneys, including mineralisation of the renal medulla, desquamation of the renal pelvis, and elevated blood urea nitrogen indicating impaired kidney function. These effects were observed across multiple studies and in both sexes. The US EPA used kidney damage in rats as the basis for setting a reference dose for biphenyl exposure.
Two-year dietary exposure in F344 rats produced dose-related kidney changes including mineralisation, pelvis hyperplasia, papillary necrosis, and elevated blood urea nitrogen at all but the lowest doses.
2002AnimalUmeda et al., Journal of Occupational Health
The US EPA set an oral reference dose of 0.05 mg/kg body weight per day for biphenyl, based on kidney injury observed in chronic animal feeding studies.
RegulatoryUS EPA Integrated Risk Information System (IRIS), Biphenyl (CASRN 92-52-4)
Bladder tumours in male rats at high doses
Male rats fed the highest test dose (4,500 ppm) for two years developed bladder tumours at a substantially elevated rate, including both papillomas and carcinomas. No bladder tumours were seen in female rats or in males at lower doses, suggesting the effect was dose-dependent and sex-specific. The US EPA concluded there is 'suggestive evidence of carcinogenic potential' based on these animal findings. No human studies have directly examined biphenyl food exposure and cancer risk.
In a 105-week rat study, significantly increased bladder carcinoma (24/50) and papilloma (10/50) were found only in male rats at 4,500 ppm. No bladder tumours occurred at lower doses or in females.
2002AnimalUmeda et al., Journal of Occupational Health
The US EPA concluded that biphenyl provides 'suggestive evidence of carcinogenic potential' in animals based on bladder tumours in male rats and liver tumours in female mice. No human carcinogenicity data were available.
RegulatoryUS EPA Integrated Risk Information System (IRIS), Biphenyl (CASRN 92-52-4)
Liver effects and genotoxicity signals
Female mice in long-term dietary studies showed increased liver tumour rates. Biphenyl and some of its metabolites have shown some ability to induce genetic damage in laboratory tests, though whether this is the driver of observed tumours in animals remains unclear. The role of genotoxicity in any human risk from food exposure has not been established.
Increased liver tumours in female BDF1 mice were observed in a long-term dietary exposure study, contributing to the US EPA's carcinogenicity classification.
AnimalUS EPA Integrated Risk Information System (IRIS), Biphenyl (CASRN 92-52-4)
Biphenyl and its metabolites have shown some capacity to induce genetic damage in laboratory studies, though the mechanistic role in the observed animal tumours is not resolved.
2016LabBetts et al., Environmental Health Perspectives (Human Health Effects of Biphenyl: Key Findings and Scientific Issues), PMC4892917
Occupational exposure effects at high doses
Workers with heavy occupational exposure to large quantities of biphenyl have reported liver damage and effects on the central and peripheral nervous system. These were high-dose industrial settings, not food-additive use levels, and the relevance to consumer dietary exposure from treated fruit peel is uncertain.
Occupational exposure to high amounts of biphenyl has been associated with reports of liver damage and central and peripheral nerve effects in workers.
2016ObservationalBetts et al., Environmental Health Perspectives (Human Health Effects of Biphenyl: Key Findings and Scientific Issues), PMC4892917
Where it stands with the regulators
Not a permitted food additive in the UK or EU. Removed from the EU permitted list in 2003; not on the UK FSA approved-additives register.
- Legal basis
- Removed from the EU food additives framework (Directive 95/2/EC on preservatives other than colours and sweeteners) by Commission Directive 2003/114/EC, which reclassified biphenyl as a plant protection product governed by Council Directive 91/414/EEC rather than a food additive. Not listed in Regulation (EC) No 1333/2008 Annex II (the current EU positive list). Not on the UK FSA approved-additives register.
- Safe-intake limit (ADI)
- No current ADI. The US EPA has set an oral reference dose (non-cancer) of 0.05 mg/kg body weight per day based on kidney effects in animals.
- History
- Biphenyl was permitted in the EU as a preservative for the surface treatment of citrus fruits under Directive 95/2/EC, at a maximum of 70mg/kg on peel. EU Directive 2003/114/EC removed it from the food additives framework, reclassifying it as a plant protection product. Commission Decision 2004/129/EC listed biphenyl in Annex I, Part C, requiring withdrawal of plant protection product authorisations by 31 March 2004. Australia does not permit biphenyl as a food additive. The US EPA classifies biphenyl as having 'suggestive evidence of carcinogenic potential' based on animal studies.
Who should be careful
Because E230 is not a permitted food additive in the UK or EU, it should not appear in food sold in these markets. Anyone who handles large quantities of biphenyl industrially should follow occupational exposure controls. On any food that legally carries a 'surface treatment' declaration for citrus, check whether the specific preservative listed is E230, E231, or E232, as E231 and E232 remain subject to their own regulatory frameworks.
The honest read
Biphenyl is no longer a live consumer food additive in the UK or EU, having been removed from the permitted list in 2003. The animal evidence that informed its removal is real: kidney damage at multiple doses and bladder tumours in male rats at the highest test dose. What these findings mean for humans at the lower exposures that would have come from treated citrus peel is genuinely uncertain. The US EPA characterises the cancer evidence as 'suggestive' rather than established. No human studies have directly examined dietary biphenyl exposure and cancer or kidney outcomes. The science is sparse partly because the additive is no longer in use.
Common questions about biphenyl
Is E230 banned in the UK?
Biphenyl is not a permitted food additive in the UK. It was removed from the EU food additives framework in 2003 and is not on the UK FSA approved-additives register. Citrus fruit sold in UK supermarkets cannot legally be treated with it as a food additive.
What health concerns led to biphenyl being removed from the EU food additives list?
The EU reclassified biphenyl as a plant protection product rather than a food additive in 2003, withdrawing authorisations by 2004. Animal studies had shown dose-related kidney damage at multiple doses and bladder tumours in male rats at the highest tested dose. The US EPA classifies it as having 'suggestive evidence of carcinogenic potential' based on animal data.
What foods contain E230?
Biphenyl was historically applied to the outer peel of citrus fruits including oranges, lemons, grapefruits, and mandarins to prevent mould during storage. It is no longer a permitted food additive in the UK or EU, so food sold in those markets should not carry it.
Is E230 vegan?
Biphenyl is a synthetic aromatic hydrocarbon and does not derive from animal products, so it would be considered vegan. However, as it is not a permitted food additive in the UK or EU, the question is largely academic for food sold in these markets.
Sources
- Umeda et al., Two-year Study of Carcinogenicity and Chronic Toxicity of Biphenyl in Rats, Journal of Occupational Health, 2002
- Betts et al., Human Health Effects of Biphenyl: Key Findings and Scientific Issues, Environmental Health Perspectives, 2016
- US EPA Integrated Risk Information System (IRIS): Biphenyl (CASRN 92-52-4)
- Commission Directive 2003/114/EC amending Directive 95/2/EC on food additives other than colours and sweeteners (removal of biphenyl from permitted list)
- Commission Decision 2004/129/EC concerning the non-inclusion of certain active substances in Annex I to Council Directive 91/414/EEC and the withdrawal of authorisations for plant protection products containing these substances (biphenyl listed in Annex I, Part C; withdrawal deadline 31 March 2004)
- UK FSA Approved Additives and E Numbers
- The Preservatives in Food Regulations 1989 (SI 1989/533) - historical UK legislation permitting biphenyl on citrus fruit
- European Parliament Question E-003415/2011 on E230 and E231
Last reviewed: 20 June 2026
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