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E239 · Preservatives

Hexamethylene tetramine

Moderate risk preservativesynthetic

Formaldehyde-releasing preservative (Provolone only).

Category
Preservatives
Acceptable daily intake
0.15 mg/kg body weight/day (EFSA)
Vegan
Yes
Vegetarian
Yes

What it is

E239, also called hexamine or urotropin, is a synthetic preservative. In the food industry, its use is extremely niche: it is legally permitted to be used almost exclusively in Provolone cheese.

How it is used in food

Prevents late-blowing defect in cheese.

Commonly found in
  • Provolone cheese (to prevent "late blowing" or gas formation by bacteria)

Health and safety

Works by slowly releasing formaldehyde.

The preservative works by slowly breaking down into formaldehyde inside the cheese, which kills Clostridium bacteria. While formaldehyde is toxic and carcinogenic in large doses, the residual amounts left in the cheese are tightly regulated and considered safe by EFSA.

Breaks down into formaldehyde

general population · evidence: not-observed

E239 works by releasing formaldehyde, a known carcinogen and toxin. However, health authorities have concluded that the minuscule amounts formed in the cheese are well within safe metabolic limits and pose no risk.

EFSA re-evaluation of hexamethylene tetramine

Its use is extremely narrowly restricted due to formaldehyde release.

Regulatory status

RegionStatusNotes
Australia & New Zealand
FSANZ		 Permitted Permitted under the FSANZ Food Standards Code.
European Union
EFSA / European Commission		 Permitted Authorised for food use under EU regulations (Annex II).
United States
FDA (Food and Drug Administration)		 Banned Not approved as a food additive.
“Banned”

Identification on labels

E-number
E239

Also printed asHexamine · Urotropin

How it is made

It is synthesised chemically by reacting formaldehyde with ammonia.

  1. Chemical Synthesis — Formaldehyde and ammonia are reacted together to form hexamethylene tetramine.

Worth knowing

Permitted in the EU only for Provolone cheese.

Conclusion

E239 is a legacy additive tied strictly to the traditional manufacturing of Provolone cheese. Unless you consume large amounts of Provolone, your dietary exposure to this additive is effectively zero.

References

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Entry last reviewed 2026-07-28.

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