What is E239?
Complete guide to understanding E239 (Hexamethylenetetramine) — a controversial preservative that releases formaldehyde in stomach acid
The Quick Answer
E239 (Hexamethylenetetramine) is a chemical preservative that works by releasing formaldehyde in stomach acid.
What makes E239 exceptional and controversial: it’s the only widely-used food additive designed to decompose and release a known carcinogen (formaldehyde). EFSA approves it for Provolone cheese only (25 mg/kg max) based on risk assessment and historical use. The USA FDA rejected it, considering formaldehyde release unacceptable in food.
E239 represents a fundamental regulatory disagreement: EU accepts minimal formaldehyde release from limited food use; USA considers even intentional release of a carcinogen unacceptable.
📌 Quick Facts
- Chemical Name: Hexamethylenetetramine; Hexamine; Methenamine
- Type: Preservative; antimicrobial; chemical compound
- Chemical formula: (CH₂)₆N₄ or C₆H₁₂N₄
- Made from: Formaldehyde + Ammonia (100% synthetic)
- Found in: Provolone cheese (EU); some canned fish (Canada, limited regions)
- Safety Status: Approved in EU (very restricted); NOT approved in USA
- Key characteristic: Releases formaldehyde in stomach acid (pH <6)
- EU Approval: Provolone cheese only; maximum 25 mg/kg
- ADI (Acceptable Daily Intake): 0.15 mg/kg body weight/day (very restrictive)
- Main concern: Intentional release of Group 1 Carcinogen (formaldehyde)
What Exactly Is It?
E239 is hexamethylenetetramine, a white crystalline compound made from formaldehyde and ammonia — 100% synthetic, chemically engineered.
Chemical structure: Cage-like hexagonal structure with carbon, hydrogen, and nitrogen atoms
Appearance: White crystalline powder; odorless or slight ammonia smell; highly soluble in water
Key properties:
– Preservative: inhibits bacterial and fungal growth
– Antimicrobial: works through formaldehyde release
– pH-dependent: only active in acidic conditions (pH <6)
– Synthetic: made from formaldehyde and ammonia
– Stable in neutral/alkaline: no activity at pH ≥6
– Metabolizable: decomposes in stomach acid
– 100% synthetic; doesn’t occur in nature
Where You’ll Find It (Very Limited)
E239 is extremely restricted — found in only a few foods globally.
| Product | Region | Permitted Level | Approval Status |
|---|---|---|---|
| Provolone Cheese | EU (PRIMARY) | 25 mg/kg maximum | Approved (traditionally used) |
| Canned/Marinated Fish | Canada; some other regions | 200 mg/kg maximum | Limited approval |
| Caviar/Herring | Limited regions | 200 mg/kg maximum | Historical use; limited |
| Other Cheeses | Limited/historical use | Variable | Declining; increasingly restricted |
| Human Food (USA) | United States | N/A | NOT APPROVED; rejected by FDA |
NOT approved for: Most foods; USA human consumption; beverages; bakery; general preservation
Rarity: E239 is one of the rarest food additives; found primarily in imported Provolone cheese
The Critical Issue: Formaldehyde Release
E239 is unique among food additives because it intentionally releases a known carcinogen.
How It Happens
In your stomach:
1. You eat food containing E239 (e.g., Provolone cheese)
2. Food enters stomach (pH 1-3, highly acidic)
3. E239 hydrolysis: Hexamethylenetetramine + stomach acid → Formaldehyde + Ammonia
4. Formaldehyde is released and absorbed
5. Your body metabolizes formaldehyde to CO₂ and water
6. Ammonia is processed normally
Timeline: Decomposition occurs relatively rapidly within stomach digestion
Formaldehyde: The Carcinogen Released
Formaldehyde classification (IARC 2015): Group 1 Carcinogen — “Sufficient evidence of carcinogenicity in humans”
Health effects of formaldehyde:
– Definitive carcinogen (nasopharyngeal cancer; sinonasal cancer; leukemia)
– Mutagen: can cause genetic damage
– Reproductive toxicant: can impair fertility/harm fetus
– No safe threshold: cancer risk increases with exposure
E239’s unique problem: No other widely-used food additive is designed to release a Group 1 carcinogen
EFSA vs. FDA: Regulatory Disagreement
| Regulator | Position | Reasoning |
|---|---|---|
| EFSA (EU) | Approved for Provolone cheese (25 mg/kg) | Risk acceptable at very restricted use level; historical safety data; minimal formaldehyde release; background formaldehyde exposure |
| FDA (USA) | NOT approved; rejected for human food | Unacceptable to intentionally add substance that releases carcinogen; zero tolerance for intentional carcinogen in food; formaldehyde is Group 1 carcinogen |
| Australia/NZ | NOT approved | Similar reasoning to FDA; stricter approach |
The core disagreement: Is it acceptable to intentionally add a substance that releases a known carcinogen if the amount is small and use is restricted?
– EU: Yes, under strict conditions and risk assessment
– USA: No, intentional release of carcinogen is unacceptable
Is E239 Safe?
EFSA’s Safety Conclusion (2014)
“The use of hexamethylene tetramine as a food additive at the present permitted maximum level (25 mg/kg for Provolone cheese) is considered safe.”
EFSA’s reasoning:
– Extensive human dietary exposure data; historical use (centuries in Provolone production)
– Formaldehyde released at permitted levels is small
– Humans naturally produce formaldehyde (metabolic byproduct)
– Natural formaldehyde in foods (apples, oranges) is higher
– Risk assessment: released formaldehyde at food use levels is acceptable
– ADI 0.15 mg/kg provides safety margin
– Approved only for Provolone cheese (extreme restriction)
FDA’s Rejection Reasoning
“E239 is not approved for human food use in the USA”
FDA’s reasoning:
– Cannot approve substance designed to release known carcinogen
– Formaldehyde is Group 1 carcinogen; no safe threshold exists
– Intentional addition of carcinogen violates fundamental food safety principle
– Even small amounts of carcinogen release unacceptable
– No adequate justification for food preservation (better alternatives exist)
Safety Assessment Details
| Criterion | Finding | Implication |
|---|---|---|
| Carcinogenicity | Releases Group 1 Carcinogen (formaldehyde) | MAJOR CONCERN; intentional release |
| Mutagenicity | Formaldehyde is genotoxic/mutagenic | Potential for genetic damage |
| Reproductive Toxicity | Formaldehyde causes reproductive harm | Concern for fertility and fetal development |
| Acute Toxicity | Low at food use levels | Safe for single exposure |
| Chronic Exposure | Carcinogen accumulation concern over lifetime | MAJOR CONCERN; cumulative risk |
| Background Exposure | Humans naturally produce formaldehyde | Added exposure increases cumulative burden |
The Bottom Line
E239 (Hexamethylenetetramine) is a controversial preservative that releases formaldehyde in stomach acid — approved in EU (Provolone only) but rejected in USA.
What you should know:
- It releases formaldehyde: In stomach acid; formaldehyde is a Group 1 Carcinogen
- EU approves it: For Provolone cheese only (25 mg/kg max); accepts risk at this level
- USA rejects it: Won’t approve intentional carcinogen release; not approved for any food
- Very restricted use: Found mainly in imported Provolone cheese; rare elsewhere
- Historical use: Traditionally used in Provolone for centuries before modern carcinogen classification
- Safety disagreement: EFSA says safe at restricted levels; FDA says unacceptable principle
- ADI is very low: 0.15 mg/kg (among the lowest for any additive)
- No health emergency: No documented widespread health problems from E239 use