Food & Drink / Compounds / 4-Methylimidazole (4-MEI)

4-Methylimidazole (4-MEI) in food: ingestion safety

Moderate risk

Dietary ingestion via caramel color IV-containing beverages and foods is the primary human exposure route for 4-MEI. Caramel color IV is the most widely used food color globally; major sources include cola drinks, dark beers, soy sauce, Worcestershire sauce, certain bread and baked goods (for color), and many processed foods. A 2011 study by Consumer Reports found that 4-MEI in 12-oz servings of major US cola brands ranged from 29 to 153 μg, exceeding the California Prop 65 threshold of 16 μg/day for daily consumers. Subsequent reformulation reduced levels substantially. In addition to caramel colors, 4-MEI is present at lower levels in roasted coffee (Maillard-derived), soy sauce, and dark roasted foods; these sources contribute minor amounts relative to caramel color IV. The WHO Joint Expert Committee on Food Additives (JECFA) last reviewed caramel colors in 2011 and established ADI specifications for caramel color classes; 4-MEI limits are regulated by EU (not more than 250 mg/kg in caramel color IV) and other jurisdictions.

What is 4-methylimidazole (4-mei)?

The IUPAC name is 5-methyl-1H-imidazole.

Also known as: 5-methyl-1H-imidazole, 4-Methylimidazole, 4-Methyl-1H-imidazole, 4(5)-Methylimidazole.

IUPAC name: 5-methyl-1H-imidazole
CAS number: 822-36-6
Molecular formula: C4H6N2
Molecular weight: 82.1 g/mol
SMILES: CC1=CN=CN1
PubChem CID: 13195

Risk for people

Moderate risk

Regulatory consensus

7 regulatory and scientific bodies have classified 4-Methylimidazole (4-MEI). The classifications differ — that's the data.

Agency	Year	Classification	Notes
IARC	2013	Group 2B (possibly carcinogenic to humans)	Classified as Group 2B based on sufficient evidence of carcinogenicity in experimental animals (lung adenomas and alveolar/bronchiolar tumors in male and female mice) and inadequate evidence in humans. 4-MEI is formed as a byproduct of the Maillard reaction during manufacturing of ammonia-process caramel colors (caramel colors III and IV), used in colas, dark beers, soy sauce, and other foods. Formation does not occur with plain caramel color I or II.
EPA CTX / IARC	—	Group 2B - Possibly carcinogenic to humans
EPA CTX / CalEPA	—	Known human carcinogen
EPA CTX / Genetox	—	Genotoxicity: negative (Ames: negative, 0 positive / 3 negative reports)
EPA CTX / Genetox	—	Genotoxicity: negative (Ames: negative, 0 positive / 3 negative reports)
EPA CTX / Skin-Eye	—	Eye Irritation: Category 2 (score: high)
EPA CTX / Skin-Eye	—	Skin Irritation: Category 2 (score: high)

Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.

Where you encounter 4-methylimidazole (4-mei)

Industrial Facilities — Manufacturing plants, Chemical storage areas, Waste treatment sites
Occupational Environments — Factories, Warehouses, Transportation vehicles
Food — processed food, beverages, candy, baked goods

Safer alternatives

Lower-risk approaches that achieve a similar outcome to 4-Methylimidazole (4-MEI):

Natural preservatives; Clean-label ingredients; Minimally processed food
Trade-offs: Consumer label appeal ('clean label'); variable efficacy depending on food matrix and target pathogen; may alter flavor/color; regulatory status varies by jurisdiction; often more expensive per unit of preservation effect.

Relative cost: 2-5× conventional

Frequently asked questions

Is 4-methylimidazole (4-mei) safe for you?

What products contain 4-methylimidazole (4-mei)?

4-Methylimidazole (4-MEI) appears in: Manufacturing plants (Industrial facilities); Chemical storage areas (Industrial facilities); Factories (Occupational environments); Warehouses (Occupational environments); processed food (Food).

Why do regulators disagree about 4-methylimidazole (4-mei)?

4-Methylimidazole (4-MEI) has been classified by 7 agencies including IARC, EPA CTX / IARC, EPA CTX / CalEPA, EPA CTX / Genetox, EPA CTX / Genetox, with differing conclusions. Regulators apply different standards of evidence (animal data weighting, exposure-pattern assumptions, epidemiological power thresholds), which is why two scientific bodies can review the same data and reach different conclusions. See the regulatory consensus table on this page for the full picture.

See 4-Methylimidazole (4-MEI) in the food app

Look up products containing 4-methylimidazole (4-mei), compare to alternatives, and explore the full data record.

Open in food View raw API data

Sources (3)

IARC Monographs Volume 101: Some Chemicals Present in Industrial and Consumer Products, Food and Drinking-Water — 4-Methylimidazole (4-MEI), Group 2B Classification, Caramel Color Formation, and Mouse Lung Tumor Evidence (2013) (2013) — academic
US FDA: Caramel Colors (Classes I–IV) — Safety Assessment, 4-MEI Formation in Ammonia-Process Caramel Colors, Dietary Exposure Estimates, and Consumer Response to Reformulation (2014) (2014) — regulatory
California OEHHA: Proposition 65 — 4-Methylimidazole Listing (2011), Significant Exposure Level (16 μg/day), Consumer Reports Testing of Cola Beverages, and Industry Reformulation Response (2011) — regulatory

Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →