What is E238?
Complete guide to understanding E238 (Calcium Formate) — an animal feed preservative NOT approved for human food
The Quick Answer
E238 (Calcium Formate) is the calcium salt of formic acid — used exclusively as an animal feed preservative and acidifier.
What makes E238 unique: unlike other formates (E236, E237), E238 has never been approved for human food. It’s exclusively an animal feed additive. It prevents spoilage in livestock feed and supports gut health in animals. EFSA confirms it’s safe for animals and consumers (through the feed chain).
E238 is fundamentally different from food additives you might consume — it’s purely for animal agriculture.
📌 Quick Facts
- Chemical Name: Calcium Formate (calcium diformate)
- Type: Animal feed preservative; technological additive; acidifier
- Chemical formula: Ca(HCOO)₂
- Found in: Animal feed ONLY (pigs, poultry, fish, ruminants, silage)
- Safety Status: Approved and safe for animals; safe for consumers (no tissue residues)
- Approved by: EFSA (2014), EU Regulation 1831/2003, FDA, most countries
- Human food approval: NONE — explicitly NOT approved for human food
- Permitted level: 15,000 mg/kg in animal feed (equivalent to ~10,000 mg formic acid/kg)
- Consumer exposure: Indirect through meat/dairy; zero residue accumulation
- Main use: Animal feed preservation and acidification; gut health support
What Exactly Is It?
E238 is calcium formate, the calcium salt of formic acid — 100% synthetic, chemically engineered and not found in nature.
Chemical structure: Ca²⁺ + 2(HCO₂⁻) ions
Appearance: White or light yellow crystalline powder; odorless; stable at room temperature
Key properties:
– Preservative: inhibits bacterial and fungal growth
– Acidifier: lowers feed pH, creating hostile environment for pathogens
– Gut health supporter: acidifies GI tract; promotes beneficial bacteria
– Calcium source: contributes dietary calcium to animals
– Stable: doesn’t decompose in feed storage (unlike volatile formic acid)
– Water soluble: highly soluble in water
– pH-dependent: solubility varies with pH
– Metabolizable: formate rapidly converts to CO₂ and water
Where You’ll Find It (Animal Feed Only)
E238 is exclusively in animal feed — nowhere else.
| Animal/Application | Use Purpose | Permitted Level |
|---|---|---|
| Pig Feed | Preservation; gut health; growth promotion | Up to 15,000 mg/kg complete feed |
| Poultry Feed (chickens, turkeys) | Feed preservation; pathogen prevention; performance | Up to 15,000 mg/kg complete feed |
| Fish Feed | Preservation; antimicrobial; water quality | Up to 15,000 mg/kg complete feed |
| Ruminant Feed (cattle, sheep, goats) | Preservation; gut health; digestion support | Up to 15,000 mg/kg complete feed |
| Silage Treatment | Ensiling agent; prevents spoilage; promotes lactic acid fermentation | Variable (agricultural use) |
| Drinking Water (animals) | Acidification; antimicrobial (limited use) | Country/regulation-specific |
NOT found in: Any human food products (EU, US, most countries)
Consumer exposure: Indirect only — through meat, dairy, eggs from animals fed E238
Is It Safe?
For Animals: Absolutely Safe
EFSA 2014 Safety Assessment:
– Target animal safety: “No adverse effects on target animals safety are anticipated” at permitted dose (15,000 mg/kg)
– Assessment: Comprehensive testing in pigs, poultry, cattle
– Conclusion: Safe for all animal species and categories
– Efficacy: Effective antimicrobial and acidifier at permitted levels
For Consumers: Zero Risk
EFSA 2014 Consumer Safety Assessment:
“Neither calcium nor formate concentrations will increase in the edible tissues of animals maintained on feed with calcium formate added and, therefore, the use of calcium formate as a feed additive in all animal species is considered safe for the consumer.”
Why zero risk?
– Formate is rapidly metabolized to CO₂ and water
– No bioaccumulation in animal tissues
– No residues transfer to meat/dairy/eggs
– Calcium is normal dietary component
– Consumer exposure is negligible
Safety Assessment Details
| Safety Criterion | Finding | Conclusion |
|---|---|---|
| Acute Toxicity (Animals) | LD₅₀ (oral, rats) ~2650 mg/kg; very low toxicity | Safe |
| Chronic Toxicity (Animals) | No adverse effects at permitted feed levels | Safe |
| Genotoxicity | No concern identified | Safe |
| Carcinogenicity | No carcinogenic potential | Safe |
| Metabolic Fate | Formate rapidly metabolizes to CO₂ + H₂O; no tissue accumulation | Safe; no residue |
| Consumer Exposure | No residues in edible tissues; negligible transfer | Safe |
| Environmental | Safe; biodegradable; formate metabolizes to CO₂ and water | Safe |
Why Animal Feed Only? Why Not Human Food?
E238 was never approved for human food — it’s exclusively an animal feed additive.
Reasons it’s animal-feed-specific:
1. No commercial driver: No manufacturer has pursued human food approval
2. Market optimization: Industry found ideal niche in animal feed preservation
3. Regulatory divergence: Feed additives (Regulation 1831/2003) and food additives (Regulation 1333/2008) are separate approval systems
4. Efficacy focus: E238 optimized for feed acidification; less relevant to human food preservation
5. Better alternatives for human food: E236/E237 already delisted; sorbates/benzoates more effective
Not a safety issue: E238 is safe; simply never submitted for human food approval
The Bottom Line
E238 (Calcium Formate) is a safe, approved animal feed preservative and acidifier with zero human food presence or approval.
What you should know:
- It’s animal-feed-only: Not approved for human food; never found in products you consume directly
- It’s safe for animals: EFSA confirmed no adverse effects at permitted levels
- It’s safe for consumers: EFSA confirmed no residues in meat/dairy/eggs
- It’s an active preservative: Widely used in modern livestock agriculture
- It’s dual-function: Both preserves feed AND supports animal gut health
- It’s approved: EU Regulation 1831/2003; EFSA 2014; FDA recognized
- No health concerns: Safe through entire feed chain to consumers