Propyl gallate
A synthetic antioxidant added to fats and oils to stop them going rancid. Used in fried foods, chewing gum and animal fats.
Propyl gallate shows oestrogen-like activity in laboratory tests and is under investigation as a potential endocrine disruptor. Animal studies produced equivocal evidence of carcinogenicity in male rats, which EFSA could not rule out at the time of its re-evaluation.
What is it?
Propyl gallate is the propyl ester of gallic acid, a polyphenolic compound. It is a white to creamy white powder synthesised by esterifying gallic acid with propanol. It is one of three gallate antioxidants permitted in food alongside octyl gallate (E311) and dodecyl gallate (E312).
What does it do?
It works by donating hydrogen atoms to free radicals produced during fat oxidation, interrupting the chain reaction that turns fats rancid. It is particularly effective in animal fats and vegetable oils and is often combined with other antioxidants such as BHA (E320) and BHT (E321) because the combination produces a stronger effect than any single antioxidant alone.
Where you will see it
Used in frying oils and shortenings, rendered animal fats such as lard and dripping, chewing gum, dehydrated meat, instant noodles, savoury snacks, biscuits and crackers. On UK labels it appears as 'propyl gallate' or 'E310'.
What the science says
Oestrogen-like activity and potential hormone disruption
Laboratory studies have found that propyl gallate can bind to oestrogen receptors and activate them, a property shared with several synthetic antioxidants. EFSA noted in its 2014 re-evaluation that in vitro oestrogenic activity was observed but whether this translates into an adverse effect in a living organism had not been established. Subsequent mixture studies have confirmed endocrine-disruptive potential when gallates are combined with other compounds.
Propyl gallate showed oestrogen receptor agonist activity in in vitro assays; EFSA noted this finding but stated that effects in an intact organism remained to be investigated.
Binary mixture studies confirmed endocrine-disruptive potential of gallate compounds including propyl gallate.
Equivocal carcinogenicity signal in animal studies
The US National Toxicology Program reported equivocal evidence of carcinogenicity in male rats in a 103-week feeding study (NTP Technical Report No. 240, December 1982). Elevated rates of preputial gland tumours, pancreatic islet-cell tumours and adrenal phaeochromocytomas were observed in low-dose male rats; female rats were classified as negative. EFSA reviewed this data and noted that the absence of a clear no-adverse-effect level in the carcinogenicity database introduced uncertainty into the risk assessment. EFSA did not conclude that propyl gallate is carcinogenic at dietary exposure levels, but could not fully resolve the uncertainty.
The NTP found equivocal evidence of carcinogenic activity of propyl gallate in male F344/N rats (elevated preputial gland, pancreatic islet-cell and adrenal phaeochromocytoma rates at low dose) and negative evidence in female rats in a 103-week feed bioassay.
EFSA noted the absence of a NOAEL in the carcinogenicity database as the key uncertainty in its risk assessment and used a 90-day toxicity study as the key study for ADI derivation.
Group ADI and exposure estimates
EFSA set a group ADI of 0.5mg per kg body weight per day for the three gallates (E310, E311, E312) combined, revised down from a previous ADI of 1.4mg/kg/day that had been set by JECFA. EFSA found that exposure estimates for some population groups, particularly children, approached or exceeded this group ADI depending on assumptions used, which it flagged as a concern.
EFSA established a group ADI of 0.5mg/kg body weight/day for gallates (E310, E311, E312) combined, based on a 90-day rat study with an uncertainty factor of 200 to account for data gaps including the carcinogenicity uncertainty.
Estimated dietary exposure in children using maximum permitted levels reached or exceeded the group ADI under high-intake scenarios.
Contact allergy and sensitivity
Propyl gallate is a recognised contact allergen and has been associated with contact dermatitis in occupational and consumer settings. Reactions in the gut from ingested propyl gallate in food have also been reported, though the evidence is largely based on case reports and small clinical series rather than controlled trials.
Propyl gallate is listed as a contact allergen; patch-test positive reactions have been documented in case series of patients with suspected cosmetic or food-related contact dermatitis.
Where it stands with the regulators
Who should be careful
People with known gallate sensitivity or contact allergy should check labels for 'propyl gallate' or 'E310'. Children who regularly eat products that are high in frying fats, snacks or chewing gum may accumulate intake across the gallate group (E310, E311, E312) more readily than adults relative to body weight, given that high-intake estimates for children approached the group ADI in EFSA's assessment.
The honest read
The science on propyl gallate has not produced a clean bill of health. EFSA lowered the acceptable intake significantly in 2014 and flagged two unresolved issues: animal carcinogenicity data it could not dismiss, and oestrogen-like activity in laboratory tests whose real-world significance in humans remains unknown. Exposure estimates for children in high-consumption scenarios were a concern in the 2014 review. These are not resolved questions; they are open ones. The additive remains permitted because regulators judge that typical exposure stays within the revised limits for most adults, but the uncertainties that drove the ADI reduction have not been closed by subsequent research.
Related additives
Common questions
Is E310 banned in the UK?
No. Propyl gallate is an authorised food additive in the UK and EU, permitted in a range of fats, oils and processed foods. It was re-evaluated by EFSA in 2014, which led to a lower acceptable daily intake, but it was not banned or suspended.
Why did EFSA lower the acceptable intake for propyl gallate in 2014?
EFSA applied a larger uncertainty factor than previous assessors because of two unresolved concerns: animal studies that produced equivocal evidence of carcinogenicity in male rats (meaning results were suggestive but not conclusive), and in vitro data showing oestrogen receptor activity. The revised group ADI of 0.5mg/kg/day for all three gallates combined replaced the previous 1.4mg/kg/day.
What foods contain E310?
Propyl gallate is used mainly in frying oils and shortenings, rendered animal fats such as lard and dripping, chewing gum, dehydrated meat products, instant noodles and some biscuits and savoury snacks. It appears on labels as 'propyl gallate' or 'E310'.
Is E310 vegan?
The additive itself is synthetic and plant-derived (gallic acid occurs in plant tannins), so propyl gallate is vegan. However, it is commonly used in animal fats such as lard and dripping, so whether a specific product containing E310 is vegan depends on the other ingredients.
Sources
- EFSA ANS Panel, Scientific Opinion on the re-evaluation of propyl gallate (E 310) as a food additive, EFSA Journal 2014
- UK FSA regulated products register, E-310 food authorisation
- EFSA FEEDAP Panel, Safety and efficacy of propyl gallate for all animal species, EFSA Journal 2020
- UK FSA Approved additives and E numbers
- NTP Technical Report Series No. 240: Carcinogenesis Bioassay of Propyl Gallate in F344/N Rats and B6C3F1 Mice (Feed Study), National Toxicology Program, December 1982
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