E233 · Thiabendazole
- WHO
- Better avoided
- FDA
- Better avoided
- EFSA
- Better avoided
- FSANZ
- Better avoided
- Japan
- Better avoided
- UK FSA
- Better avoided
- Health Canada
- Better avoided
What is E233?
Thiabendazole is a fungicide applied to the surface of fruits and vegetables, especially bananas, citrus, and potatoes, to prevent mold during storage and transport. It's also used in human and veterinary medicine to treat parasitic worm infections, though those are much higher, therapeutic doses compared with trace food residues. As a post-harvest treatment, residues are concentrated in peels and skins, so washing or peeling produce reduces exposure. It's approved for food use within regulated residue limits by the FDA and EFSA.
Also appears on labels as: Thiabendazole, TBZ, E233, E 233, E-233, INS 233, 2-(4-Thiazolyl)benzimidazole, 4-Thiazolylbenzimidazole, Thiabendazol, Thia Bendazole, Thia-bendazole, ThiaB.
What the evidence says
- Peel/skin residues can be relatively high; washing or peeling treated produce reduces exposure.
- At the much higher doses used medicinally, thiabendazole has been linked to nausea, dizziness, and rare liver effects; typical dietary residue exposure is far below these levels.
Research behind the verdict
- Thiabendazole (E233) – Antifungal Preservative — EFSA Panel on Food Additives, EFSA Journal (2014). ADI maintained by EFSA/JECFA; high doses show liver toxicity in animals; mainly on citrus fruits; low risk at regulated exposure.[avoid]
Frequently asked questions
Is E233 safe?
Our overall verdict for E233 (Thiabendazole) is “Better avoided”, based on the most cautious of the major regulators’ positions — FDA: better avoided; WHO: better avoided; EFSA: better avoided; FSANZ: better avoided; Japan: better avoided; UK FSA: better avoided; Health Canada: better avoided.
Is E233 vegan, halal or gluten-free?
According to our ingredient data for Thiabendazole — vegan: yes, vegetarian: yes, halal: yes, kosher: yes, gluten-free: yes, dairy-free: yes. Manufacturing sources can vary between products; check the label if it matters to you.
What is E233 and why is it used?
Thiabendazole is a fungicide applied to the surface of fruits and vegetables, especially bananas, citrus, and potatoes, to prevent mold during storage and transport. It's also used in human and veterinary medicine to treat parasitic worm infections, though those are much higher, therapeutic doses compared with trace food residues. As a post-harvest treatment, residues are concentrated in peels and skins, so washing or peeling produce reduces exposure. It's approved for food use within regulated residue limits by the FDA and EFSA.
Does E233 contain allergens?
No known allergens are recorded for Thiabendazole.
Watch E233
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This page summarises publicly available regulatory assessments and research. It is general information, not medical advice. Sources: EFSA, FDA, WHO and the studies linked above.