Chlorothalonil (Ref: DS 2787)

Chlorothalonil (Ref: DS 2787)	Last updated: 22/10/2025
(Also known as: TPN; tetrachloroisophthalonitrile; m-TCPN; HSR002825)

SUMMARY

Chlorothalonil is a broad-spectrum fungicide. It has a low aqueous solubility, is volatile and would not be expected to leach to groundwater. It is slightly mobile. It tends not to be persistent in soil systems but may be persistent in water. It has a low mammalian toxicity but there is some concern regarding its bioaccumulation potential. It is a recognised irritant. Chlorothalonil is moderately toxic to birds, honeybees and earthworms but considered to be more toxic to aquatic organisms.

Hazard alerts

The following alerts are based on the data in the tables below. An absence of an alert does not imply the substance has no implications for human health, biodiversity or the environment but just that we do not have the data to form a judgement. These hazard alerts do not take account of usage patterns or exposure, thus do not represent risk.

Environmental fate	Ecotoxicity	Human health
Environmental fate Moderate alert: Drainflow: Slightly mobile; Potential for particle bound transport: Medium	Ecotoxicity High alert: Fish acute ecotoxicity: High; Fish chronic ecotoxicity: High; Daphnia acute ecotoxicity: High; Daphnia chronic ecotoxicity: High	Human health High alert: Endocrine disruptor

GENERAL INFORMATION

Description

A fungicide used to control a wide range of diseases on a broad range of crops. Also used as a wood preservative.

Example pests controlled

Rust; purple spot; Leaf blight; Anthracnose; Downy mildew; Ring spot; Stalk rot; Botrytis rot; Pod & stem blight

Example applications

Cereals; Vegetables including asparagus, beans, cabbage, cauliflower, broccoli, carrot, onions, celery, curcubits; Corn for seed; Fruit including cranberries, melon; Mushrooms; Peanuts; Potatoes; Ornamentals

Efficacy & activity

Can be product specific but generally - Wheat/Mildew=Low; Wheat/Septori tritici=High; Barley/Rhynchosporium=Low; Barley/Ramularia=Moderate

GB regulatory status

GB COPR regulatory status

Not approved

Date COPR inclusion expires

Expired

GB LERAP status

No UK approval for use as a plant protection agent

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Not approved

Dossier rapporteur/co-rapporteur

Netherlands/Belgium

Date EC 1107/2009 inclusion expires

Expired

EU Candidate for substitution (CfS)

Listed in EU database

Yes

Approved for use (✓) under EC 1107/2009 in the following EU Member States

ATAustria	BEBelgium	BGBulgaria	CYCyprus	CZCzech Republic	DEGermany	DKDenmark	EEEstonia	ELGreece
	✓	✓	✓	✓
ESSpain	FIFinland	FRFrance	HRCroatia	HUHungary	IEIreland	ITItaly	LTLithuania	LULuxembourg
	✓					✓
LVLatvia	MTMalta	NLNetherlands	PLPoland	PTPortugal	RORomania	SESweden	SISlovenia	SKSlovakia
	✓		✓	✓	✓			✓

Approved for use (✓) under EC 1107/2009 by Mutual Recognition of Authorisation and/or national regulations in the following EEA countries

ISIceland	NONorway

Additional information

Also used in

Australia; USA

Chemical structure

Isomerism

None

Chemical formula

C₈Cl₄N₂

Canonical SMILES

C(#N)C1=C(C(=C(C(=C1Cl)Cl)Cl)C#N)Cl

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

CRQQGFGUEAVUIL-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C8Cl4N2/c9-5-3(1-13)6(10)8(12)7(11)4(5)2-14

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
chlorothalonil	-

General status

Pesticide type

Fungicide

Substance groups

Chloronitrile fungicide; Nitrile fungicide

Minimum active substance purity

985 g kg⁻¹

Known relevant impurities

EU dossier - Hexachlorobenzene 0.04 g kg⁻¹; Decachlorobiphenyl 0.03 g kg⁻¹

Substance origin

Synthetic

Mode of action

Non-systemic, broad-spectrum, foliar action with some protectant properties. Acts by preventing spore germination and zoospore motility. Multi-site activity.

CAS RN

1897-45-6

EC number

217-588-1

CIPAC number

288

US EPA chemical code

081901

PubChem CID

15910

CLP index number

608-014-00-4

Molecular mass

265.91

PIN (Preferred Identification Name)

2,4,5,6-tetrachlorobenzene-1,3-dicarbonitrile

IUPAC name

tetrachloroisophthalonitrile

CAS name

2,4,5,6-tetrachloro-1,3-benzenedicarbonitrile

Listed (✓) under

UK Poisons List Order 1972	Rotterdam Convention	Montreal Protocol
XNo The Poisons List Order 1972	XNo Rotterdam Convention	XNo Montreal Protocol
Stockholm Convention	OSPAR	EU Water Framework Directive
XNo Stockholm Convention	XNo OSPAR	XNo EU Water Framework Directive

Relevant Environmental Water Quality Standards

UK Environment Agency non-statutory standard for the protection of aquatic life: freshwater and saltwater annual average 0.1 µg l⁻¹, max acceptable conc 1.0 µg l⁻¹

Forever chemical

Highly Hazardous Pesticide (HHP)

Type I

Type II

Yes [; ; ; ]

Other status information

PAN Bad Actor Chemical

Herbicide Resistance Class (HRAC MoA class)

Not applicable

Herbicide Resistance Class (WSSA MoA class)

Not applicable

Insecticide Resistance Class (IRAC MoA class)

Not applicable

Fungicide Resistance Class (FRAC MOA class)

M05

Examples of recorded resistance

Physical state

White crystalline solid at 99.6% purity

Related substances & organisms

bromothalonil

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1964, first reported

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

AgriGuard
Certis
DuPont
Nufarm
Scotts
Syngenta
Teliton
Walabi

Example products using this active

Alto Elite
Amistar Opti
Bravo 500
Cherokee
Credo
Folio
Joules
Merlin
Midas
Repulse

Formulation and application details

Usually supplied as a soluble concentrate that is mixed with water and applied as a foliar spray

Commercial production

Chlorothalonil is produced commercially through a multi-step chemical synthesis involving chlorinated aromatic compounds. There are two main synthetic routes. The main method is chlorination of isophthalonitrile. This involves starting with isophthalonitrile and undergoing a chlorination step using chlorine gas under controlled conditions to produce chlorothalonil. Alternatively, chlorothalonil can be produced via the dehydration of tetrachloroisophthaloyl amide.

Impact on climate of production and use

Whilst the amount of CO₂e produced during the production of chlorothalonil will depend on the precise method, Audsley et al. (2009) reported that it takes 313 MJ of energy per kg produced. This is equivalent to approximately 21.6 kg CO₂e. There will also be emissions associated with packaging, transport and application.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

Solubility - In water at 20 °C at pH 7 (mg l⁻¹)

0.81

at 25°C

Low

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

13800

Ethyl acetate

18000

Acetone at 25°C

1700

Methanol at 25°C

74400

Xylene

Melting point (°C)

252.1

Boiling point (°C)

347

Degradation point (°C)

347

Flashpoint (°C)

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

8.71 X 10⁰²

Calculated

Log P

2.94

Moderate

Fat solubility of residues

Solubility

Insoluble

Data type

Regulatory data

Density (g ml⁻¹)

1.74

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

0.076

Low volatility

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

2.50 X 10^-02

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

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

232nm = 62390, 312nm = 1116, 324nm = 1507

Surface tension (mN m⁻¹)

71.5

at 21.5 °C 99.8%

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Not readily biodegradable

Soil degradation (days) (aerobic)

DT₅₀ (typical)

3.53

Non-persistent

DT₅₀ (lab at 20 °C)

3.53

Non-persistent

DT₅₀ (field)

17.9

Non-persistent

DT₉₀ (lab at 20 °C)

24.7

Non-persistent

DT₉₀ (field)

59.5

DT₅₀ modelling endpoint

4.29

geometric mean of lab studies

Note

EU dossier 2018: lab studies DT₅₀ range 0.256-19.0 days, DT₉₀ range 1.46-68.2 days, Soils=18; field studies DT₅₀ range 7.44-28.4 days, DT₉₀ range 24.7-94.2 days; Other sources: 30 days (DW3)

Dissipation rate RL₅₀ (days) on plant matrix

Value

5.5

Note

Published literature RL₅₀ range 3.0-12.5 days, 8 field & undercover grown crops, various matrices, n=11

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

5.0

Note

Published literature RL₅₀ range 1.7-12.7 days, 11 field & undercover grown crops, various matrices, n=21

Aqueous photolysis DT₅₀ (days) at pH 7

Value

0.72

Fast

Note

In sterile buffer

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

Value

29.6

at 50 °C

Non-persistent

Note

Stable pH 4 to pH 7

Water-sediment DT₅₀ (days)

0.57

Fast

Water phase only DT₅₀ (days)

0.82

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)

42.99

Slightly mobile

K_oc (mL g⁻¹)

2632

Notes and range

EU dossier RAR 2016; K_d range 7.7-153 mL g⁻¹, K_oc range 300-6154 mL g⁻¹, Soils=9

Freundlich

K_f (mL g⁻¹)

27.2

Slightly mobile

K_foc (mL g⁻¹)

1288

¹/_n

0.90

Notes and range

EU RAR 2016: K_f range 3.0-74.1 mL g⁻¹, K_foc range 330-7000 mL g⁻¹, ¹/_n range 0.83-0.95, Soils=12; Literature data: K_f range 96.3-1357 mL g⁻¹, K_foc range 13462-52585 mL g⁻¹, ¹/_n range 0.48-0.69, Soils=8

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.12

Calculated

Low leachability

SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate

Value

2.05 X 10^-02

Calculated

Note

Potential for particle bound transport index

Medium

Calculated

Potential for loss via drain flow

Slightly mobile

Calculated

Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk

41172

Calculated using the Atkinson method. EU trigger for long-range transport is DT₅₀ in air <2 days.

Substance of concern for long-range air transport

Bio-concentration factor

BCF (l kg⁻¹)

100

Threshold for concern

CT₅₀ (days)

Known soil metabolites

Metabolite

Major/Minor fraction

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

Estimated maximum occurrence fraction

Notes

4-hydroxy-2,5,6-trichloroisophtalonitrile (Ref: R182281)

Major fraction

0.322

2-amido-3,5,6-trichlo-4-cyanobenzenesulphonic acid (Ref: R417888)

Major fraction

0.152

3-carbamyl-2,4,5-trichlorobenzoic acid (Ref: R611965)

Major fraction

0.132

4-amido-2,5-dichloro-6-cyano benzene-1,3-disulfonic acid (Ref: R419492)

Major fraction

0.124

2,5 dichloro-4,6 dicyano-benzene-1,3 disulfonic acid (Ref: R418503)

Minor fraction

0.060

,4-bis-amido-3,5,6-trichlorobenzenesulfonate (Ref: R471811)

Major fraction

0.119

2,4,5-trichloro-3-cyano-6-hydroxy-benxamide (Ref: SYN507900)

Minor fraction

0.058

2,4,5-trichloro-3-cyano benzamid (Ref: R611966)

Minor fraction

0.081

2,3,6-trichloro-5-cyanobenzamide (Ref: R611967)

Major fraction

0.132

2,4,5-trichloro-3-cyano-6-hydroxybenzamide (Ref: R611968)

Minor fraction

0.065

2,3,4,6-tetrachloro-5-cyanobenzamide (Ref: R613636)

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-carbamyl-2,4,5-trichlorobenzoic acid (Ref: R611965)

Not relevant

2,5 dichloro-4,6 dicyano-benzene-1,3 disulfonic acid (Ref: R418503)

Relevant

4-amido-2,5-dichloro-6-cyano benzene-1,3-disulfonic acid (Ref: R419492)

Relevant

2,4,5-trichloro-6-hydroxy-benzene-1,3-disulfonic acid (Ref: SYN548008)

Relevant

2,4,5-trichloro-3-cyano-6-hydroxy-benxamide (Ref: SYN507900)

Relevant

2-amido-3,5,6-trichlo-4-cyanobenzenesulphonic acid (Ref: R417888)

Relevant

4-carbamoyl-2,3,5-trichloro-6-cyanobenzene-1-sulfonic acid (Ref: SYN548581)

Relevant

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

2-acetamido-3-[3-(2-acetamido-3-hydroxy-3-oxopropyl)sulfanyl-2,5-dichloro-4,6-dicyano-phenyl]sulfanylpropanoic acid (Ref: R613823)

Rat

2,5 dichloro-4,6 dicyano-benzene-1,3 disulfonic acid (Ref: R418503)

Crop

2-acetamido-3-[3,5-bis[(2-acetamido-3-hydroxy-3-oxo-propyl)sulfanyl]-4-chloro-2,6-dicyano-phenyl] sulfanylpropanoic acid (Ref: R613825)

Rat

,4-bis-amido-3,5,6-trichlorobenzenesulfonate (Ref: R471811)

Crop

2,4,5-trichloro-3-cyanobenzamide (Ref: R611966)

Rat

2,3,6-trichloro-5-cyanobenzamide (Ref: R611967)

Rat

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)

Rat

High

(ppm diet)

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

100

Rat Reproductive NOAEL

Moderate

Birds - Acute LD₅₀ (mg kg⁻¹)

> 2000

Coturnix japonica

Low

Birds - Short term dietary (LC₅₀/LD₅₀)

> 5200 mg kg feed⁻¹

Coturnix japonica

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

58.2

Colinus virginianus NOAEL

Moderate

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

268.5

Eisenia foetida

Moderate

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

50.0

Eisenia foetida

Moderate

Soil micro-organisms

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

Dose: 4.8 mg kg⁻¹ soil

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Folsomia candida

Non-target plants

Vegetative vigour ER₅₀ (g ha⁻¹)

> 4000

Avena sativa Allium cepa

Seedling emergence ER₅₀ (g ha⁻¹)

> 4000

4 plant species tested

Honeybees (Apis spp.)

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

> 101

Apis mellifera

Low

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

> 63

Apis mellifera

Moderate

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

Chronic as 10-day LDD₅₀ µg bee⁻¹ day⁻¹

53.9

Apis mellifera

Notes

Bumblebees (Bombus spp.)

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

> 100

Bombus terrestris

Low

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

> 94

Bombus terrestris

Moderate

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)

8.8% Mortality at dose up to 7.67 g ha⁻¹

Chrysoperla carnea

Beneficial insects (Parasitic wasps) as Mortality LR₅₀ g ha⁻¹, Glass plate

> 262

Aphidius rhopalosiphi

Low

Beneficial insects (Predatory mites) as Mortality LR₅₀ g ha⁻¹, Glass plate

> 2095

Typhlodromus pyri

Low

Beneficial insects (Ground beetles)

0% Mortality at dose 1.5 kg ha⁻¹

Poecilus cupreus

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

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

0.017

Oncorhynchus mykiss

High

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

0.0014

Pimephales promelas

High

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

0.083

Danio rerio EC₅₀ Embryo

High

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

0.054

Daphnia magna

High

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

0.009

Daphnia magna

High

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

0.156

Ceriodaphnia dubia LC₅₀

Moderate

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

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

0.061

Chironomus riparius

High

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

0.04

Chironomus riparius

Moderate

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

Aquatic Plants (free-floating, fonds growth, fresh) - 7 day (mg l⁻¹) (EC₅₀)

0.29

Lemna gibba

Moderate

Aquatic plants (rooted, growth rate, fresh) - 14 day (mg l⁻¹) (EC₅₀)

> 0.08

Myriophyllum spicatum 21 day

Moderate

Algae - Acute (growth rate, fresh; mg l⁻¹) (72 hr ErC₅₀, Static)

0.013

Navicula pelliculosa

Moderate

Algae - Chronic (growth rate, fresh; mg l⁻¹) (72 hr NOEC, Static)

0.0035

Navicula pelliculosa

Moderate

Mesocosm study data

NOEAEC mg l⁻¹

Marine bivalves – LOEC, mortality (mg l⁻¹)

0.53

Crassostrea gigas

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

Rabbit

Mammals - Inhalation LC₅₀ (mg l⁻¹)

0.1

Rat 4 hr (nose only)

Other Mammal toxicity endpoints

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

0.015

Rat SF=100

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

0.05

Rat SF=100

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

0.01

Rat SF=100

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

0.003

Rat SF=100

Dermal penetration studies (%)

0.02-1.2

concentration dependent

Dangerous Substances Directive 76/464

Exposure Routes

Public

Low risk for prescribed pattern of use

Occupational

PPE/PPC recommended/advised

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

UK MRL for Chlorothalonil is set to be reduced to the limit of quantification from September 2022

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

Mammalian dose elimination route and rate

Mammals eliminate almost all of the chemical in faeces (65-90%), urine and expired air

Health issues

Specific human health issues (hazard-based)

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

Eye irritant

Phototoxicant

General human health issues

May cause contact dermatitis
IARC group 2B carcinogen; US EPA - probable human carcinogen, formation of tumours shown to form in mice following ingestion; CLP data - suspected carcinogen
Endocrine issues - Activation of androgen-sensitive cells proliferation

Handling issues

Property

Value and interpretation

General

Avoid generating spray mists/dust
Not explosive or oxidising
IMDG Transport Hazard Class 6.1
Not expected to auto-ignite; Not highly flammable

CLP classification 2013

Health: H317, H318, H330, H335, H351
Environment: H400, H410

WHO Classification

U (Unlikely to present an acute hazard)

UN Number

UN2811

Waste disposal & packaging

Packaging Group II (moderate danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

chlorothalonil

French

chlorothalonil

German

Chlorthalonil

Danish

chlorothalonil

Italian

clorotalonil

Spanish

clorotalonil

Greek

chlorothalonil

Polish

chlorotalonil

Swedish

Hungarian

chlotalonil

Dutch

chloorthalonil

Norwegian

Record last updated:	22/10/2025
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