Teflubenzuron (Ref: CME 13406)

Teflubenzuron (Ref: CME 13406)	Last updated: 04/09/2025
(Also known as: tefluron)

GENERAL INFORMATION

Description

An acyl urea derivate classified as an insecticide for use in aquaculture

Examples of veterinary uses

Used mainly to control sea lice in fisheries

Examples of species treated

Fish

Approval status

VMR 2013/2033 approval status (GB/UK)

Approved - usually available as a prescription only medicine to be authorised by a veterinarian (POM-V)

EU Regulatory approval status

Approved

Chemical structure

Isomerism

None

Chemical formula

C₁₄H₆Cl₂F₄N₂O₂

Canonical SMILES

C1=CC(=C(C(=C1)F)C(=O)NC(=O)NC2=CC(=C(C(=C2F)Cl)F)Cl)F

Isomeric SMILES

International Chemical Identifier key (InChIKey)

CJDWRQLODFKPEL-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C14H6Cl2F4N2O2/c15-5-4-8(12(20)10(16)11(5)19)21-14(24)22-13(23)9-6(17)2-1-3-7(9)18/h1-4H,(H2,21,22,23,24)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
teflubenzuron	-

General status

Veterinary substance type

Insecticide, Antiparasitic

Substance groups

Benzoylphenylurea insecticide; Phenylurea insecticide; Urea insecticide

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Systemic. Inhibitor of chitin biosynthesis affecting CHS1.

Molecular targets

[Chitin synthesis (CHS1), Inhibitor]

CAS RN

83121-18-0

EC number

617-441-5

CIPAC number

450

US EPA chemical code

PubChem CID

91734

CLP index number

No data found

Therapeutic Class

Antiparasitic products, insecticides & repellents: Ecoparasiticides, insecticides & repellents

ATCvet Code

QP53BC03

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: Salmonidae)

Molecular mass

381.11

PIN (Preferred Identification Name)

N-[(3,5-dichloro-2,4-difluorophenyl)carbamoyl]-2,6-difluorobenzamide

IUPAC name

1-(3,5-dichloro-2,4-difluorophenyl)-3-(2,6-difluorobenzoyl)urea

CAS name

N-(((3,5-dichloro-2,4-difluorophenyl)amino)carbonyl)-2,6-difluorobenzamide

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

White to yellow crystals

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1983, first reported; 1984, introduced Thailand

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

BASF
Trouw Ltd

Example products using this active

Nemolt
Nomolt
Tefluron
Dart
Sag 134
Calcide Teflubenzuron Premix Medicated Feed

Formulation and application details

Often supplied as a suspension concentrate that is mixed with water and used as a crop spray or as a feed pre-mix for animal use

Commercial production

Teflubenzuron is synthesised through a multi-step organic process designed to construct its complex difluorinated and dichlorinated aromatic structure. The production typically begins with the preparation of two key intermediates: a substituted benzoyl chloride and a substituted phenylurea. One route involves reacting 2,6-difluorobenzoyl chloride with 3,5-dichloro-2,4-difluoroaniline to form the urea linkage central to teflubenzuron’s structure. This condensation reaction is carried out under controlled conditions, often using solvents like toluene and a base such as triethylamine to facilitate the coupling. The final compound is then purified.

Impact on climate of production and use

Data for the amount of life cycle GHGs produced by teflubenzuron are not available in the public domain. However, whilst estimates vary, more general data suggests that between 14 and 19 kilograms of CO₂e is emitted per kilogram of insecticide produced.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

0.01

Low

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

8850

Acetone

n-Heptane

1060

Methanol

740

Toluene

Melting point (°C)

225

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

225

Flashpoint (°C)

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

2.00 X 10⁰⁴

Calculated

Log P

4.3

High

Fat solubility of residues

Solubility

Soluble

Data type

Regulatory data - observed in metabolism and farm animal feeding studies

Density (g ml⁻¹)

1.66

Dissociation constant pKa) at 25 °C

9.2

Weak acid

Vapour pressure at 20 °C (mPa)

9.16 X 10^-04

Low volatility

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

6.98 X 10^-03

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

24 hr

Volatilisation is not considered critical for air pollution

From soil surface

24 hr

Volatilisation is not considered critical for air pollution

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

Neutral solution: 249nm = 13543
Acidic solution: 251nm = 15153
Basic solution: 262nm = 21115

Surface tension (mN m⁻¹)

Refractive Index

Environmental release

Substance may enter the environment via the faeces of treated animals or by leaching from spilt medicated feed.

Degradation

Property

Value

Source; quality score; and other information

Interpretation

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Moderately persistent

DT₅₀ (lab at 20 °C)

92.1

Moderately persistent

DT₅₀ (field)

13.7

Non-persistent

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

45.4

Note

EU dossier lab studies DT₅₀ range 62.2-140.3 days; field studies DT₅₀ range 8.8-16.4 days, DT₉₀ range 29.2-53.2 days

Manure DT₅₀ (days)

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Moderately fast

Note

Data for artificial light

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

Value

Stable

Note

pH sensitive: Stable at pH 5, 8.7 days at pH 9, at pH 7 95% of substance remained after 30 days

Water-sediment DT₅₀ (days)

16.4

Fast

Water phase only DT₅₀ (days)

7.3

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)

534

Non-mobile

K_oc (mL g⁻¹)

26062

Notes and range

EU dossier K_d range 169-944 mL g⁻¹, koc range 21139-32556 mL g⁻¹, Soils=4

Freundlich

K_f (mL g⁻¹)

K_foc (mL g⁻¹)

¹/_n

Notes and range

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

-0.47

Calculated

Low leachability

Bio-concentration factor

BCF (l kg⁻¹)

640

Threshold for concern

CT₅₀ (days)

0.8

Known soil metabolites

Metabolite

Major/Minor fraction

$Click here for further information on Major/Minor fraction$

Estimated maximum occurrence fraction

Notes

3,5-dichloro-2,4-difluorophenylurea

Major fraction

0.107

3,5-dichloro-2,4-difluoroaniline

Minor fraction

0.054

3,5-dichloro-2,4-dichlorophenylurea

Major fraction

0.104

Known groundwater metabolites

Metabolite

EC SANCO/221/2000 relevancy

ADI (mg kg⁻¹ bodyweight day⁻¹)

WHO drinking water guidance value (μg L⁻¹ day⁻¹)

3, 5-dichloro-2,4-difluoroaniline

Relevancy unknown

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

2,6-difluorobenzoic acid

Plant

5-chloro-2,4-difluoroaniline

Plant

1-(3,5-dichloro-2,4-difluorophenyl)-3-(2,6-difluoro-3-hydroxybenzoyl)urea

Animal

1-(3,5-dichloro-2,4-difluorophenyl)-5-fluoro-4alpha,8aalpha-dihydroquinazoline-2,4(1H,3H)-dione

Surface water/sediment

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 5038

Rat

Low

Mammals - Short term dietary NOEL

(mg kg⁻¹)

> 1

Rat

High

(ppm diet)

> 100

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

Birds - Acute LD₅₀ (mg kg⁻¹)

> 2250

Colinus virginianus

Low

Birds - Short term dietary (LC₅₀/LD₅₀)

> 5000 mg kg feed⁻¹

Colinus virginianus

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

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

> 500

Eisenia foetida corr

Moderate

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

8.0

Eisenia andrei

Moderate

Soil micro-organisms

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

Dose: 2 mg kg⁻¹ soil 28 Day

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Non-target plants

Vegetative vigour ER₅₀ (g ha⁻¹)

> 120

7 plant species tested

Seedling emergence ER₅₀ (g ha⁻¹)

> 120

7 plant species tested

Honeybees (Apis spp.)

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

100

Apis mellifera

Moderate

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

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

0.73

Chrysoperla carnea

Moderate

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

> 180

Aphidius rhopalosiphi

Low

Beneficial insects (Predatory mites) as Mortlity LR₅₀ g ha⁻¹, Extented lab study

> 89.6

Typhlodromus pyri

Moderate

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)

> 0.0065

Lepomis macrochirus

High

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

0.0186

Oncorhynchus mykiss

Moderate

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

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

0.0028

Daphnia magna

High

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

0.000062

Daphnia magna

High

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

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

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

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

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

0.05

Chironomus riparius

High

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) (72 hr ErC₅₀, Static)

> 0.02

Desmodesmus subspicatus

Moderate

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

Mesocosm study data

NOEAEC mg l⁻¹

0.000005

Aquatic invertebrates NOEC

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)

> 5038

Rat

Low

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 5.04

Rat 4 hr (nose only)

Other Mammal toxicity endpoints

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

0.01

Mouse SF=200

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

None allocated

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

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

0.016

SF=500

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

List II

Exposure Routes

Public

No unacceptable risks to bystanders identified

Occupational

Predicted exposure to workers is within acceptable levels
Potential risk to operators, PPE/PPC advised

Mammalian dose elimination route and rate

Rapidly and completely absorbed and excreted mainly in the 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

No further information available

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

U (Unlikely to present an acute hazard)

UN Number

UN3077

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

teflubenzuron

French

teflubenzuron

German

Teflubenzuron

Danish

teflubenzuron

Italian

teflubenzuron

Spanish

teflubenzuron

Greek

Polish

teflubenzuron

Swedish

Hungarian

teflubenzuron

Dutch

teflubenzuron

Norwegian

Record last updated:	04/09/2025
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