Ammonium polyphosphates
An ammonium phosphate salt not currently approved as a food additive in the UK or EU. Its E number is allocated but it has no permitted food uses.
E545 is not an authorised food additive in the UK or EU. If you see it declared on a food label, the product may not comply with food law.
What is it?
Ammonium polyphosphates are inorganic salts formed from phosphoric acid and ammonia, existing as chains of phosphate units with ammonium counter-ions. The compound is best known as an industrial flame retardant and is used in fertilisers and fire-suppression coatings. It carries the E545 designation in the European numbering system, but this number has not been activated with permitted food uses under EU or UK law.
What does it do?
In industrial applications, ammonium polyphosphates act by releasing ammonia and phosphoric acid when heated, forming a char layer that blocks oxygen and slows combustion. In fertiliser use, they supply both nitrogen and phosphorus to plants. No authorised food-technology function exists under current UK or EU food additive law.
Where you will see it
Ammonium polyphosphates are not authorised for use as food additives, so they should not appear as an ingredient in any food sold in the UK or EU. The compound is used industrially in intumescent fire-retardant paints, coatings, and agricultural fertilisers. On a food label, it would appear as 'ammonium polyphosphates' or 'E545', neither of which is a lawfully declared food additive in this market.
What the science says
Regulatory status: not authorised as a food additive
The UK FSA Register of Food Additive Authorisations and assimilated EU Regulation 1333/2008 (Annex II) set out every additive permitted in food sold in the UK and EU. E545 does not appear on either list. A direct search of the FSA Register at data.food.gov.uk returns no results for E545. An E number being allocated does not, by itself, mean authorisation for food use has been granted. Without an entry in Annex II or the FSA Register, the use of E545 in food is not permitted.
A direct search of the UK FSA Register of Food Additive Authorisations at data.food.gov.uk/regulated-products returns no results for E545, confirming it is not an authorised food additive in Great Britain. The Register became the operative post-Brexit list of authorised food additives on 1 April 2025.
E545 is absent from the UK FSA's approved additives and E numbers list, which mirrors the authorised list under assimilated EU Regulation 1333/2008.
Annex II of EU Regulation 1333/2008 does not include an entry for E545 ammonium polyphosphates, meaning it has no permitted food uses in the EU. Only E541 (sodium aluminium phosphate) appears in the E540-E549 range on the authorised list.
No EFSA scientific opinion has been published specifically on E545 ammonium polyphosphates as a food additive. EFSA's phosphate re-evaluations cover E338-341, E343, and E450-452; E545 falls outside that authorised group and has not been assessed.
Phosphate burden and kidney function
While E545 itself has no authorised food use, the broader class of inorganic phosphate food additives (E338-E343, E450-E452) has attracted regulatory scrutiny. EFSA's 2019 re-evaluation of permitted phosphates found that total dietary phosphate intake from all sources, including food additives, may approach or exceed levels of concern in people with impaired kidney function. People with chronic kidney disease are advised to limit dietary phosphate. This context is relevant to understand why ammonium polyphosphates have not been authorised for food use.
EFSA's 2019 re-evaluation of phosphoric acid and phosphate salts (E338-E343, E450-E452) concluded that existing exposure estimates from food additive phosphates alone could approach the tolerable upper intake level for phosphorus in some population groups, particularly those with existing kidney disease.
Where it stands with the regulators
Who should be careful
No one should encounter E545 in a lawfully produced food in the UK or EU, as it is not an authorised food additive. If you see 'ammonium polyphosphates' or 'E545' on a food label, the product's compliance with UK food law should be questioned and the matter reported to the UK FSA.
The honest read
E545 is one of several E numbers that exist in the numbering system but have never been brought into the authorised list for food use. The absence is not an oversight: ammonium polyphosphates have an established industrial identity as flame retardants, and no food technology application has been assessed and approved by regulators. There is no consumer science to weigh here in the usual sense, because the compound is not in the food supply through lawful channels. The concern flag is set because its presence on a food label would indicate a non-compliant product.
Related additives
Common questions
Is E545 banned in the UK?
It has not been authorised for food use in the UK or EU, so its use in food is not permitted. It was never granted approval under EU Regulation 1333/2008 Annex II, which the UK retained after Brexit. The post-Brexit UK FSA Register of Food Additive Authorisations (operative from 1 April 2025) also contains no entry for E545. Strictly speaking, it is 'not authorised' rather than 'banned following a previous approval', but the practical effect is the same: it cannot lawfully be used in food sold in the UK.
Why does E545 have an E number if it is not approved for food?
The E number system allocates codes to substances that have been evaluated or are under consideration, not only to those that have been approved. Some numbers in the 500s range (mineral salts and related compounds) were allocated to ammonium compounds that were studied but never given a positive authorisation for food use. Having an E number does not mean a substance is permitted in food.
What foods contain E545?
None lawfully. E545 is not an authorised food additive in the UK or EU, so it should not appear in any food sold here. Its real-world uses are as an industrial flame retardant in paints and coatings, and as a phosphorus and nitrogen source in agricultural fertilisers.
Is E545 vegan?
Ammonium polyphosphates are produced from inorganic raw materials (phosphoric acid and ammonia) and contain no animal-derived components. The question of vegan status is largely academic given that E545 is not an authorised food additive and should not be present in any food.
Sources
- UK FSA: Register of Food Additive Authorisations (data.food.gov.uk)
- UK FSA: Approved Additives and E Numbers
- EU Regulation (EC) No 1333/2008 on food additives, Annex II
- EFSA ANS Panel: Re-evaluation of phosphoric acid and phosphates (E 338-341, E 343, E 450-452) as food additives, EFSA Journal 2019
- European Commission Food Additives Database
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