Stannous chloride
A tin salt used as an antioxidant and colour-keeper in one specific food: canned white asparagus. Rarely encountered.
What is it?
Stannous chloride (tin(II) chloride) is an inorganic tin salt. In food it appears as the dihydrate form (SnCl2.2H2O). Tin is a metal; in this form it carries a +2 charge, giving it reducing (electron-donating) properties.
What does it do?
Acts as an antioxidant by donating electrons to oxidising molecules, slowing the browning and colour loss that occurs when white asparagus is canned. It keeps the pale vegetable from discolouring during sterilisation and storage.
Where you will see it
Authorised in the UK and EU for one food only: canned or bottled white asparagus. It is not permitted in any other food category. Between 2013 and 2018 the Mintel global food database found no EU or Norwegian products that labelled it, suggesting it is rarely if ever used in modern production. On a label it appears as 'stannous chloride' or 'E512'.
What the science says
Tin toxicity at high doses
Inorganic tin compounds can irritate the stomach lining at high concentrations. The original safety limits for tin in food were based on gastric irritancy, with a threshold concentration identified at around 200mg of tin per kilogram of food. Exposure from the single authorised use of E512 in white asparagus is far below that threshold.
JECFA established a Provisional Maximum Tolerable Daily Intake of 2mg tin per kilogram of bodyweight in 1982, based on gastric irritancy as the critical effect. This was later expressed as a weekly intake of 14mg/kg bodyweight.
The maximum permitted level for E512 in canned white asparagus is 25mg Sn per kilogram. Estimated mean dietary exposure from this use was below 1.3 micrograms of tin per kilogram of bodyweight per day across all age groups, orders of magnitude below the JECFA tolerable intake.
Genotoxicity: mixed signals in the lab, negative in living organisms
Some laboratory cell tests showed stannous chloride could interact with DNA, possibly because tin ions generate reactive oxygen species. However, when tested in living animals, no lasting DNA damage was found. The EFSA panel concluded there is no genotoxicity concern at food-relevant doses.
In vitro bacterial and mammalian cell tests produced some genotoxic signals, attributed to reactive oxygen species generation by tin ions. In vivo rodent studies (rat and mouse) found no evidence of permanent DNA damage.
Carcinogenicity: no signal in long-term animal studies
Chronic toxicity and cancer studies in rats and mice did not raise concern for carcinogenicity. Stannous chloride is not classified by IARC.
Long-term chronic toxicity and carcinogenicity studies in rodents did not indicate concern for carcinogenicity of stannous chloride.
Real-world exposure: effectively nil
A scan of the Mintel global food product database covering 2013 to 2018 found no EU or Norwegian products labelling E512. This suggests the additive, though legally permitted, is largely unused in modern food manufacturing.
Mintel GNPD data (2013-2018) found stannous chloride (E512) was not labelled on any products in the EU or Norway, indicating negligible real-world consumer exposure from this additive.
Where it stands with the regulators
Who should be careful
There are no population groups identified as needing to avoid E512 specifically. Tin is a heavy metal and people with rare tin sensitivity should check canned white asparagus labels for 'stannous chloride' or 'E512', though such sensitivity is not a recognised clinical condition in UK food allergy guidance.
The honest read
E512 occupies an unusual position: it is a permitted additive in law, but one that appears to have dropped out of use in practice. The Mintel product database found it on no EU food labels in the five years before the 2018 EFSA review. The science is well characterised for an additive of this age. Tin at high doses irritates the gut, which is why the safety limits were set conservatively, but actual exposure from the one food it is permitted in runs at a fraction of a percent of the tolerable intake. The EFSA 2018 re-evaluation did flag a genuine gap: no manufacturer provided real use-level data, so the assessment relied on worst-case legal maximums rather than what is actually added to food. That gap has not been closed, but given the additive appears to be commercially dormant, it has not driven further action.
Related additives
Common questions
Is E512 banned in the UK?
No. E512 is a permitted food additive in the UK, authorised under the UK FSA approved-additives list (derived from EU Regulation 1333/2008). It is restricted to one specific use: canned or bottled white asparagus only.
Is stannous chloride actually used in food today?
Rarely, if at all. A scan of the Mintel global food product database from 2013 to 2018 found no EU or Norwegian products carrying E512 on their label, suggesting manufacturers have moved away from it despite its legal permission.
What foods contain E512?
Under UK and EU law, E512 is only permitted in canned or bottled white asparagus. It is not authorised in any other food category. On a label it reads 'stannous chloride' or 'E512'.
Is E512 vegan?
Yes. Stannous chloride is a mineral salt (a compound of tin and chloride) with no animal-derived ingredients or processing.
Sources
- Re-evaluation of stannous chloride (E 512) as food additive - EFSA Journal 2018
- Re-evaluation of stannous chloride (E 512) as food additive - PMC full text
- UK FSA Approved Additives and E Numbers
- EU Food Additives Listing by E Number - Bryant Research
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