E233 - Thiabendazole

At a glance

• What it is: A lab‑made antifungal compound also used as a pesticide
• Main role in food: Post‑harvest surface preservative to prevent mold and rot on fruit peels
• Where it shows up: Especially citrus and bananas; typically on the outer surface
• Regulatory view: Treated as a pesticide; authorities set residue limits and monitor compliance
• Home tip: Washing and peeling can reduce residues on produce

Why is Thiabendazole added to food?

Thiabendazole helps prevent mold and rot after harvest, which keeps fruit from spoiling during storage and transport.^[U.S. EPA overview of Thiabendazole and its registered post‑harvest uses — U.S. Environmental Protection Agency. https://www.epa.gov/ingredients-used-pesticide-products/thiabendazole]

What foods contain Thiabendazole?

You’ll most often find it on the peels of some fruits, such as citrus and bananas, where it is applied to control post‑harvest diseases.^[EU Pesticides Database: information on active substance uses and maximum residue levels — European Commission. https://food.ec.europa.eu/safety/plant-protection-products/eu-pesticides-database_en] It is intended for the surface, not the edible interior, and it is not commonly used in processed foods.

What can replace Thiabendazole?

• Other post‑harvest surface preservatives historically used on fruit include biphenyl and orthophenyl phenol, depending on local rules and crop needs.
• Non‑chemical options include better sorting, rapid cooling, controlled‑atmosphere storage, and improved packaging.
• In processed foods (not fresh fruit), different preservative systems are used, such as sorbic acid or potassium sorbate, when appropriate for the product style and regulations.

How is Thiabendazole made?

Thiabendazole is a synthetic benzimidazole compound produced by multi‑step organic synthesis, not extracted from natural sources.^[Compound Summary: Thiabendazole — National Institutes of Health, PubChem. https://pubchem.ncbi.nlm.nih.gov/compound/Thiabendazole] Manufacturers make it to high purity for agricultural or pharmaceutical applications.

Is Thiabendazole safe to eat?

Food safety agencies treat thiabendazole as a pesticide, not a typical food additive. In the United States, the Environmental Protection Agency (EPA) sets legal residue limits for pesticides on foods, and these tolerances are listed in the Code of Federal Regulations.^[Tolerances and exemptions for pesticide chemical residues in food (40 CFR Part 180) — U.S. eCFR. https://www.ecfr.gov/current/title-40/chapter-I/subchapter-E/part-180] The FDA monitors foods for pesticide residues, including post‑harvest fungicides, to check that levels meet the legal limits.^[Pesticides: FDA monitoring of pesticide residues in foods — U.S. Food and Drug Administration. https://www.fda.gov/food/pesticides]

In the European Union, authorities also assess active substances like thiabendazole and set maximum residue levels (MRLs) for specific crops.^[EU Pesticides Database: information on active substance uses and maximum residue levels — European Commission. https://food.ec.europa.eu/safety/plant-protection-products/eu-pesticides-database_en] When used according to approved conditions, regulators consider these residue limits protective of consumer health.^[Pesticides: FDA monitoring of pesticide residues in foods — U.S. Food and Drug Administration. https://www.fda.gov/food/pesticides]

Does Thiabendazole have any benefits?

• Helps reduce mold growth on fruit peels, supporting quality during shipping and storage^[U.S. EPA overview of Thiabendazole and its registered post‑harvest uses — U.S. Environmental Protection Agency. https://www.epa.gov/ingredients-used-pesticide-products/thiabendazole]
• Can lower food losses from spoilage, which is especially important for long supply chains

Who should avoid Thiabendazole?

• People who prefer to minimize any pesticide exposure can choose organic options when available, or peel fruit before eating. Washing under running water also helps reduce residues.^[Selecting and Serving Produce Safely — U.S. Food and Drug Administration. https://www.fda.gov/food/buy-store-serve-safe-food/selecting-and-serving-produce-safely]
• Anyone with a known sensitivity to benzimidazole drugs or similar compounds should speak with a healthcare professional for personalized advice.

Myths & facts

• Myth: “If a fruit was treated post‑harvest, the inside is unsafe.”
  Fact: Post‑harvest fungicides like thiabendazole are applied to the peel. Regulators set residue limits and monitor compliance to help ensure safety.^[Tolerances and exemptions for pesticide chemical residues in food (40 CFR Part 180) — U.S. eCFR. https://www.ecfr.gov/current/title-40/chapter-I/subchapter-E/part-180]
• Myth: “Washing does nothing.”
  Fact: Rinsing under running water and peeling can reduce residues on the surface of produce.^[Selecting and Serving Produce Safely — U.S. Food and Drug Administration. https://www.fda.gov/food/buy-store-serve-safe-food/selecting-and-serving-produce-safely]

Thiabendazole in branded foods

You usually won’t see E233 listed on ingredient panels of packaged foods. When used, it is typically a post‑harvest treatment on whole fruits. Retail labeling practices vary by country, but the product is intended for surface protection rather than mixing into recipes.

References