Thiabendazole (Ref: MK 360)

Thiabendazole (Ref: MK 360)	Last updated: 12/09/2025
(Also known as: tiabendazole; TBZ; tebuzate)

GENERAL INFORMATION

Description

A veterinary anthelmintic agent that is now rarely used.

Examples of veterinary uses

Used for the treatment of certain bacterial, mycotic, and inflammatory dermatoses, and otitis externa

Examples of species treated

Sheep; Goats; Cattle; Pigs; Poultry; Cats; Dogs

Approval status

VMR 2013/2033 approval status (GB/UK)

Not approved

EU Regulatory approval status

Not approved

Chemical structure

Isomerism

None

Chemical formula

C₁₀H₇N₃S

Canonical SMILES

C1=CC=C2C(=C1)NC(=N2)C3=CSC=N3

Isomeric SMILES

International Chemical Identifier key (InChIKey)

WJCNZQLZVWNLKY-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C10H7N3S/c1-2-4-8-7(3-1)12-10(13-8)9-5-14-6-11-9/h1-6H,(H,12,13)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
thiabendazole	-

General status

Veterinary substance type

Antiparasitic; Anthelminic agent

Other bioactivity & uses

Biocide; Disinfectant; Slimicide; Wood preservative

Substance groups

Benzimidazole fungicide; Thiazole fungicide

Minimum active substance purity

985 g kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

Systemic with curative and protective action. Acts by compromising the cytoskeleton through a selective interaction with beta-tubulin.

Molecular targets

[Beta-tubulin, Inhibitor]

CAS RN

148-79-8

EC number

205-725-8

CIPAC number

323

US EPA chemical code

060101

PubChem CID

5430

CLP index number

613-054-00-0

Therapeutic Class

Antiparasitics products, insecticides & repellents: Anthelmintics

ATCvet Code

QP52AC10

Controlled Drug?

Regulation 37/2010 MRL Classification

Molecular mass

201.25

PIN (Preferred Identification Name)

2-(1,3-thiazol-4-yl)-1H-1,3-benzimidazole

IUPAC name

2-(thiazol-4-yl)benzimidazole

CAS name

2-(4-thiazolyl)-1H-benzimidazole

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

UK Environment Agency non-statutory standard for the protection of freshwater and saltwater aquatic life 5 µg l⁻¹ as annual average, 50 µg l⁻¹ as max acceptable conc

Physical state

Colourless to yellow-white powder

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1961, discovered; 1964, first reported, 1967 first approved

Example manufacturers & suppliers of products using this active now or historically

AgriGuard
Merial
Syngenta

Example products using this active

Hykeep
Storite
Tezate
Tecto
Tobaz

Formulation and application details

Formulations include dry powders, soluble liquids and suspension concentrates

Commercial production

The production of thiabendazole involves a multi-step organic synthesis based around the formation of its fused heterocyclic structure. A common method begins with 2-aminobenzimidazole and a thiazole-4-carboxylic acid derivative, which undergo a condensation reaction facilitated by a carboxylic acid activator. This is followed by oxidation, hydrolysis under alkaline conditions, and acidification, ultimately forming the thiabendazole core. Catalysts are used to promote ring closure and improve yield. Modern approaches aim to optimise this process using green chemistry principles, reducing environmental impact while enhancing purity and efficiency

Impact on climate of production and use

Data for the amount of life cycle GHGs produced by thiabendazole are not available in the public domain. However, whilst estimates vary, more general data suggests that between 11 and 30 kilograms of CO₂e is emitted per kilogram of fungicide produced.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

Solubility - In water at 20 °C (mg l⁻¹)

Moderate

Solubility - In organic solvents at 20 °C (mg l⁻¹)

n-Heptane

130

Xylene

8230

Methanol

2430

Acetone

Melting point (°C)

297

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

Octanol-water partition coefficient at pH 7, 20 °C

2.45 X 10⁰²

Calculated

Log P

2.39

Low

Fat solubility of residues

Solubility

Insoluble

Data type

Regulatory data based on LogP

Density (g ml⁻¹)

1.4

Dissociation constant pKa) at 25 °C

4.73

pKa(2) 12.00

Vapour pressure at 20 °C (mPa)

5.30 X 10^-04

Low volatility

Henry's law constant at 25 °C (Pa m³ mol⁻¹)

3.70 X 10^-06

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

Maximum UV-vis absorption L mol⁻¹ cm⁻¹

Neutral: 234nm=15201, 242nm=15436, 299nm=23213, 312nm=16438
Acidic: 244nm=11554, 303nm=25775, 316nm=16920
Basic: 234nm=16013, 300nm=19700

Surface tension (mN m⁻¹)

72.7

Refractive Index

Environmental release

Degradation

Property

Value

Source; quality score; and other information

Interpretation

Soil degradation (days) (aerobic)

DT₅₀ (typical)

500

Very persistent

DT₅₀ (lab at 20 °C)

1000

Very persistent

DT₅₀ (field)

724

Very persistent

DT₉₀ (lab at 20 °C)

1000

Very persistent

DT₉₀ (field)

Note

EU dossier 2001

Manure DT₅₀ (days)

Aqueous photolysis DT₅₀ (days) at pH 7

Value

1.2

Moderately fast

Note

Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7

Value

203

Persistent

Note

Stable pH 5 to pH 9

Water-sediment DT₅₀ (days)

Fast

Water phase only DT₅₀ (days)

1.6

Moderately fast

Sediment phase only DT₅₀ (days)

Air degradation

As this parameter is not normally measured directly, a surrogate measure is used: ‘Photochemical oxidative DT₅₀’. Where data is available, this can be found in the Fate Indices section below.

Decay in stored produce DT₅₀

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d (mL g⁻¹)

Slightly mobile

K_oc (mL g⁻¹)

3983

Notes and range

EU dossier 2014 K_d range 26-120 mL g⁻¹; K_oc range 1200-11000 mL g⁻¹, Soils=6; Other data: K_oc ~ 2500 mL g⁻¹ (DW3)

Freundlich

K_f (mL g⁻¹)

35.5

Slightly mobile

K_foc (mL g⁻¹)

2091

¹/_n

0.79

Notes and range

EU dossier 2014 K_f range 13-100 mL g⁻¹, K_foc range 580-3921 mL g⁻¹, ¹/_n range 0.72-0.90, Soils =5

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.94

Calculated

Transition state

Bio-concentration factor

BCF (l kg⁻¹)

96.5

Low potential

CT₅₀ (days)

Not available

Known soil and groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

5-hydroxythiabendazole

NOA415696

Animal

benzimidazole-2-carboxamide

Surface water

benzimidazole-2-carboxylic acid

1,2-dihydro-3-hydroxy-quinoxaline

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 5000

Rat

Low

Mammals - Short term dietary NOEL

(mg kg⁻¹)

> 10

Rat

High

(ppm diet)

Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)

Rat Reproductive NOAEL

Moderate

Birds - Acute LD₅₀ (mg kg⁻¹)

> 2250

Colinus virginianus

Low

Birds - Short term dietary (LC₅₀/LD₅₀)

> 5620 mg kg feed⁻¹

Colinus virginianus

Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)

34.9

Colinus virginianus

Moderate

Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)

> 500

Eisenia foetida corr

Moderate

Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)

2.1

Eisenia foetida corr

Moderate

Soil micro-organisms

Nitrogen mineralisation: No significant adverse effect
Carbon mineralisation: No significant adverse effect

Dose: 9 mg kg⁻¹ soil

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Folsomia candida corr

Non-target plants

Vegetative vigour ER₅₀ (g ha⁻¹)

Seedling emergence ER₅₀ (g ha⁻¹)

Honeybees (Apis spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

> 34

Apis mellifera

Moderate

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

> 4.0

Apis mellifera

Moderate

Unknown mode acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Chronic

Notes

Bumblebees (Bombus spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Mason bees (Osmia spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Other bee species (1)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Other bee species (2)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Beneficial insects (Ladybirds)

Beneficial insects (Lacewings) as Mortality LR₅₀ g ha⁻¹, Extended lab study

> 1800

Chrysoperla carnea

Low

Beneficial insects (Parasitic wasps) as Mortality LR₅₀ g ha⁻¹, Std lab test

> 1800

Aphidius rhoipalosiphi Adult

Low

Beneficial insects (Predatory mites) as Mortality LR₅₀ g ha⁻¹, Std lab test

> 1800

Typhlodromus pyri Protonymph

Low

Beneficial insects (Ground beetles)

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Temperate Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

0.55

Oncorhynchus mykiss

Moderate

Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)

0.012

Oncorhynchus mykiss

Moderate

Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

6.09

Danio rerio EC₅₀ Embryo

Moderate

Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

0.81

Daphnia magna

Moderate

Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)

0.042

Daphnia magna

Moderate

Tropical Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)

0.34

Americamysis bahia

Moderate

Sediment dwelling organisms - Acute 96 hour LC₅₀ (mg l⁻¹)

Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l⁻¹)

2.0

Chironomus riparius 21 day

Moderate

Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg⁻¹)

3.0

Chironomus riparius

Moderate

Aquatic Plants (free-floating, fonds growth, fresh) - 7 day (mg l⁻¹)

Aquatic plants (rooted, growth rate, fresh) - 14 day (mg l⁻¹)

Algae - Acute (growth rate, fresh; mg l⁻¹) (EC₅₀)

9.0

Raphidocelis subcapitata

Moderate

Algae - Chronic (growth rate, fresh; mg l⁻¹) (NOEC)

3.2

Unknown species

Low

Mesocosm study data

NOEAEC mg l⁻¹

Marine bivalves

HUMAN HEALTH AND PROTECTION

General

Property

Value

Source; quality score; and other information

Interpretation

Threshold of Toxicological Concern (Cramer Class)

High (class III)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 5000

Rat

Low

Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)

5000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 0.53

Rat

Other Mammal toxicity endpoints

ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)

0.1

ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)

0.1

AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)

AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)

0.07

Dermal penetration studies (%)

0.15-1.84%

concentration dependent

Dangerous Substances Directive 76/464

Exposure Routes

Public

No unacceptable risks to bystanders identified

Occupational

No unacceptable risks to operators or other workers identified

Mammalian dose elimination route and rate

Excretion is achieved mainly through urine (~90%) in the form of various metabolites, <5% through faeces

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

No data found

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

No data found

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

Possible thyroid, liver, spleen and kidney toxicant
US EPA - likely to be human carcinogen at high doses

Handling issues

Property

Value and interpretation

General

Not explosive or oxidising
IMDG Transport Hazard Class 9
Not expected to auto-ignite; Not highly flammable

CLP classification 2013

Environment: H400, H410

WHO Classification

III (Slightly hazardous)

UN Number

UN3077

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

thiabendazole

French

thiabendazole

German

Thiabendazol

Danish

E 233, thiabendazole

Italian

tiabendazolo

Spanish

tiabendazol

Greek

thiabendazol

Polish

tiabendazol

Swedish

tiabendazol

Hungarian

thiabendazole

Dutch

thiabendazool

Norwegian

Record last updated:	12/09/2025
Contact:	aeru@herts.ac.uk
Please cite as:	Lewis, K.A., Tzilivakis, J., Warner, D. and Green, A. (2016) An international database for pesticide risk assessments and management. Human and Ecological Risk Assessment: An International Journal, 22(4), 1050-1064. DOI: 10.1080/10807039.2015.1133242