Dichlobenil (Ref: H 133)

Dichlobenil (Ref: H 133)	Last updated: 11/01/2021
(Also known as: dichlorbenil; DCBN)

SUMMARY

Dichlobenil is a herbicide that was largely used for general annual and perennial weed control in non-copped. It is no longer approved for use within the EU. It has low solubility, is not highly volatle and has potential to leach into groundwater. It is moderately persistent in soils and very persistent in water. It is moderately toxic to mammals, aquatic organisms, honeybees and earthworms.

GENERAL INFORMATION

Description

A herbicide for woody crops, non-crop uses and in, for example, established orchards. Can also be a pesticide transformation product

Example pests controlled

Canada thistle; Quackgrass; Timothy; Wild rocket; Fescue; Curly Dock; Knapweed; Spurge; Bluegrass; Crabgrass; Pigweed; Knotweed

Example applications

Fruit including apples, cherry, grape, pear, filbert, blueberry, gooseberry, blackberry, raspberry, loganberry; Non-cropped areas including recreational areas, industrial sites, pathways

Efficacy & activity

Availability status

Current

Introduction & key dates

1960, first reported

UK regulatory status

UK COPR regulatory status

Not approved

Date COPR inclusion expires

Expired

UK LERAP status

None

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Not approved

Dossier rapporteur/co-rapporteur

Date EC 1107/2009 inclusion expires

Expired

EU Candidate for substitution (CfS)

Not applicable

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

Also used in

Chemical structure

Isomerism

None

Chemical formula

C₇H₃Cl₂N

Canonical SMILES

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

Isomeric SMILES

N#Cc1c(Cl)cccc1Cl

International Chemical Identifier key (InChIKey)

YOYAIZYFCNQIRF-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C7H3Cl2N/c8-6-2-1-3-7(9)5(6)4-10/h1-3H

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
dichlobenil	-

General status

Pesticide type

Herbicide, Metabolite

Metabolite Type

Soil

Substance group

Benzonitrile

Minimum active substance purity

980 g kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

Systemic. Inhibition of cell wall synthesis.

CAS RN

1194-65-6

EC number

214-787-5

CIPAC number

US EPA chemical code

027401

PubChem CID

3031

Molecular mass

172.01

PIN (Preferred Identification Name)

2,6-dichlorobenzonitrile

IUPAC name

2,6-dichlorobenzonitrile

CAS name

2,6-dichlorobenzonitrile

Other status information

Potential groundwater contaminant; Chemical subject to PIC regulations

Relevant Environmental Water Quality Standards

Herbicide Resistance Classification (HRAC)

Herbicide Resistance Classification (WSSA)

Insecticide Resistance Classification (IRAC)

Not applicable

Fungicide Resistance Classification (FRAC)

Not applicable

Examples of recorded resistance

Physical state

White crystalline solid

Can be a metabolite of:

Parent

Formation medium

Estimated maximum occurrence fraction

1107/2009 relevancy

chlorthiamid

Soil

Formulations

Property

Value

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

Dichlobenil Granules
Casoron G
Osorno
Norosac

Example products using this active

Certis
Luxan
Nufarm
Scotts
Shell
Duphar

Formulation and application details

Often supplied as granules applied directly to the soil by mechanical spreaders or by hand

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

21.2

at 25 °C

Low

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

86000

Acetone

53000

Xylene

3700

Cyclohexane

151000

Dichloromethane

Melting point (°C)

144.5

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

120

Flashpoint (°C)

Not expected to self ignite; Not highly flammable

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

5.01 X 10⁰²

Calculated

Log P

2.7

Moderate

Bulk density (g ml⁻¹)

1.40

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

0.00014

Low volatility

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

1.317

Moderately volatile

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

298.9nm = 1985.3
290nm = 1878.8
243nm = 5766.9
236.9nm = 6805.9
211nm = 38528.8

Surface tension (mN m⁻¹)

68.5

at 20°C

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Moderately persistent

DT₅₀ (lab at 20 °C)

24.15

Non-persistent

DT₅₀ (field)

5.4

Non-persistent

DT₉₀ (lab at 20 °C)

114.5

Persistent

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

EU dossier Lab studies DT₅₀ range 21.98-26.26 days, DT₉₀ range 129-145 days; Field studies DT₅₀ range 3.4-72 days, DT₉₀ range 104.6-122.56 days; Other sources: DT₅₀ 1-6 months (general literature); 60 days (DW4)

Dissipation rate RL₅₀ on plant matrix

Value

Note

Dissipation rate RL₅₀ on and in plant matrix

Value

Note

Aqueous photolysis DT₅₀ (days) at pH 7

Value

15.1

Slow

Note

Natural light

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

Value

Stable

Note

Stable pH 6.8 to 8.3, Rapidly hydrolysed in strong acidic media.

Water-sediment DT₅₀ (days)

142

Slow

Water phase only DT₅₀ (days)

10.5

Moderately fast

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

Moderately mobile

K_oc

257

Notes and range

Other sources: 45-400 mL g⁻¹

Freundlich

K_f

6.4

Moderately mobile

K_foc

237

¹/_n

0.844

Notes and range

EU dossier K_f range 0.3-10.5 mL g⁻¹, K_foc range 133-322 mL g⁻¹, ¹/_n 0.75-1.02, Soils=5

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.19

Calculated

Low leachability

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

Value

4.39 X 10^-03

Calculated

Note

Potential for particle bound transport index

Medium

Calculated

Potential for loss via drain flow

Moderately mobile

Calculated

Key metabolites

Metabolite

Formation medium

Estimated maximum occurrence fraction

1107/2009 relevancy

2,6-dichlorobenzamide (Ref: AE C653711)

Soil

0.694

Major fraction

2,6-dichlorobenzoic acid

Soil

0.660

Major fraction

O-chlorobenzamide (Ref: OBAM)

Soil

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Metabolising enzymes

4-chloro-2(3H)benzoxazolone

Surface water

0.0913

2-chlorobenozoic acid

Surface water

0.17

ECOTOXICOLOGY

Property

Value

Source; quality score; and other information

Interpretation

Bio-concentration factor

BCF (l kg⁻¹)

100

Threshold for concern

CT₅₀ (days)

1.0

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 2000

Rat

Low

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat 2 year

(ppm diet)

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

Birds - Acute LD₅₀ (mg kg⁻¹)

698

Colinus virginianus

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

> 5200 mg kg feed⁻¹

Colinus virginianus

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

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

7.2

Oncorhynchus mykiss

Moderate

Fish - Chronic 21 day NOEC (mg l⁻¹)

0.66

Oncorhynchus mykiss

Moderate

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

6.2

Daphnia magna

Moderate

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

1.2

Daphnia magna

Moderate

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

1.74

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)

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

Aquatic plants - Acute 7 day EC₅₀, biomass (mg l⁻¹)

0.0279

Lemna gibba

Moderate

Non-target plants

Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)

111

Pseudokirchneriella subcapitata

Low

Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)

Honeybees (Apis spp.)

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

Moderate

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

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

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 pollinators (1)

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

Mode of exposure

Other pollinators (2)

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

Mode of exposure

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

135

Eisenia foetida corr

Moderate

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

Other soil macro-organisms

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

>= 33.8

Folsomia candida 28d corr

Other arthropod (1)

LR₅₀ g ha⁻¹

% Effect

Other arthropod (2)

LR₅₀ g ha⁻¹

% Effect

Soil micro-organisms

Mesocosm study data

NOEAEC mg l⁻¹

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)

> 2000

Rat

Low

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

0.25

Rat

Other Mammal toxicity endpoints

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

0.01

proposed Dog SF=100

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

0.45

proposed Rabbit SF=100

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

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

0.01

proposed Dog SF=100

Dermal penetration studies (%)

1.4

Dangerous Substances Directive 76/464

Exposure Routes

Public

Negligible risks for the prescribed applications

Occupational

Acceptable risks for the prescribed applications

MRLs

European

EU MRL pesticide database

Notes

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

No data found

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

Possible liver, kidney, stomach and parathyroid toxicant
May cause dermatitis
Chronic exposure may cause sedation, lose of appetite and severe respiratory problems
USEPA - possible human carcinogen

Handling issues

Property

Value and interpretation

General

Not explosive or oxidising
IMDG Transport Code is usually 9

CLP classification 2013

Health: H302
Environment: H411

EC Risk Classification

Xn - Harmful: R21
N - Dangerous for the environment: R51, R53

EC Safety Classification

S2, S36/37, S61

WHO Classification

III (Slightly hazardous)

UN Number

Usually 3077

Waste disposal & packaging

Packaging Group III (minor danger)

TRANSLATIONS

Language

Name

English

dichlobenil

French

dichlobenil

German

Dichlobenil

Danish

diclobenil

Italian

diclobenil

Spanish

diclobenil

Greek

dichlobenil

Polish

dichlobenyl

Swedish

Hungarian

dichlobenil

Dutch

dichlobenil

Record last updated:	11/01/2021
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