Dicamba (Ref: SAN 837H)

Dicamba (Ref: SAN 837H)	Last updated: 22/08/2024
(Also known as: dianat; disugran; dicamba acid)

SUMMARY

Dicamba is a selective, systemic herbicide used for general weed control. It is highly soluble in water, volatile and has a low potential to leach to groundwater based on its chemical properties. It is not persistent in soil but, under certain conditions, it may persist in aquatic systems. It is moderately toxic to mammals but has a low potential to bioaccumulate. It is an irritant. it is moderately toxic to birds, most aquatic species, honeybees and earthworms.

Data 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.

Environmental fate	Ecotoxicity	Human health
Environmental fate High alert: Drainflow: Very mobile	Ecotoxicity Moderate alert: Birds acute ecotoxicity: Moderate; Birds chronic ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate; Bees acute contact ecotoxicity: Moderate; Bees acute oral ecotoxicity: Moderate; Earthworms chronic ecotoxicity: Moderate	Human health Moderate alert: Mammals acute toxicity: Moderate; Possible Carcinogen; Reproduction/development effects; Neurotoxicant

GENERAL INFORMATION

Description

A herbicide for control of annual and perennial broad-leaved weeds and brush species

Example pests controlled

Bedstraw; Buttercup; Carpetwed; Cocklebur; Lambsquarters; Mallow; Goosefoot; Pigweed; Sowthistle; Velvetleaf; Knapweed; Teasel; Plantains; Bindweed; Thistles

Example applications

Cotton; Sugarcane; Soybeans; Sorghum; Asparagus; Grass seed crops; Non-cropland; Cereals including wheat, triticale, oats, maize, rye

Efficacy & activity

Shown to be efficiatious via field trials and extensive global use.

Availability status

Current

Introduction & key dates

circa 1963, introduced

GB regulatory status

GB COPR regulatory status

Approved

Date COPR inclusion expires

31/12/2029

GB LERAP status

Check label - may vary with formulation

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

Denmark/Romania

Date EC 1107/2009 inclusion expires

31/03/2027

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, Morocco

Chemical structure

Isomerism

Isomeric - also occurs as 3,5-dichloro-2-methoxybenzoic acid

Chemical formula

C₈H₆Cl₂O₃

Canonical SMILES

COC1=C(C=CC(=C1C(=O)O)Cl)Cl

Isomeric SMILES

Clc1ccc(Cl)c(c1OC)C(=O)O

International Chemical Identifier key (InChIKey)

IWEDIXLBFLAXBO-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C8H6Cl2O3/c1-13-7-5(10)3-2-4(9)6(7)8(11)12/h2-3H,1H3,(H,11,12)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
dicamba	Unstated isomer

General status

Pesticide type

Herbicide, Plant Growth Regulator

Substance groups

Benzoic acid herbicide; Benzoic acid PGR

Minimum active substance purity

850 g kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

Selective, systemic, absorbed through leaves and translocates throughout plant. Synthetic auxin.

CAS RN

1918-00-9

EC number

217-635-6

CIPAC number

US EPA chemical code

029801

PubChem CID

3030

CLP index number

607-043-00-X

Molecular mass

221.04

PIN (Preferred Identification Name)

3,6-dichloro-2-methoxybenzoic acid

IUPAC name

3,6-dichloro-o-anisic acid

CAS name

3,6-dichloro-2-methoxybenzoic acid

Other status information

Potential groundwater contaminant

Relevant Environmental Water Quality Standards

Herbicide Resistance Class (HRAC MoA class)

Herbicide Resistance Class (WSSA MoA class)

Insecticide Resistance Class (IRAC MoA class)

Not applicable

Fungicide Resistance Class (FRAC MOA class)

Not applicable

Examples of recorded resistance

Physical state

White granules with aromatic odour

Related substances & organisms

dicamba biproamine

dicamba diglycolamine

dicamba diolamine

dicamba sodium

Formulations

Property

Value

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

Certis
Headland
Nufarm UK
Scotts
Bayer

Example products using this active

Di-Farmon R
Foundation
Prompt
Relay P
Banval
Xtendimax

Formulation and application details

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

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

250000

High

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

500000

Acetone

2800

Hexane

500000

Methanol

500000

Ethyl acetate

Melting point (°C)

115

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

230

Flashpoint (°C)

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

1.58 X 10^-02

Calculated

Log P

-1.80

Low

Fat solubility of residues

Solubility

Insoluble

Data type

Regulatory data

Density (g ml⁻¹)

1.484

Dissociation constant pKa) at 25 °C

1.87

Strong acid

Vapour pressure at 20 °C (mPa)

1.67

at 25 °C

Low volatility. If applied directly to plants or soil, drift is a concern & mitigation is advisable

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

5.06 X 10^-05

at 25 °C

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

0.12

24 hr

Volatilisation is not considered critical for air pollution

From soil surface

1.15

24 hr

Volatilisation is not considered critical for air pollution

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

Neutral solution: 228nm = 10130, 280nm = 737
Acidic solution: 228nm = 10119/10522, 280nm = 1028/350

Surface tension (mN m⁻¹)

72.2

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Not readily biodegradable

Soil degradation (days) (aerobic)

DT₅₀ (typical)

9.62

Non-persistent

DT₅₀ (lab at 20 °C)

9.62

Non-persistent

DT₅₀ (field)

3.9

Non-persistent

DT₉₀ (lab at 20 °C)

32.4

Moderately persistent

DT₉₀ (field)

13.2

DT₅₀ modelling endpoint

Note

EU 2021 dossier lab aerobic studies (corrected) DT₅₀ range 3.2-24.6 days, DT₉₀ (measured) range 10.7-81.7 days, Soils=7; field studies DT₅₀ range 3.2-4.9 days, DT₉₀ range 10.8-18.4 days; Other sources: DT₅₀ 14-25 days (R3)

Dissipation rate RL₅₀ (days) on plant matrix

Value

9.5

Note

Grass, n=1

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

5.7

Note

Published literature RL₅₀ range 2.9-8.5 days, Kentucky bluegrass thatch, n=2

Aqueous photolysis DT₅₀ (days) at pH 7

Value

50.3

Stable

Note

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

Value

Stable

Note

Stable pH 7 to pH 9

Water-sediment DT₅₀ (days)

Moderately fast

Water phase only DT₅₀ (days)

Stable

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)

K_oc (mL g⁻¹)

Notes and range

Freundlich

K_f (mL g⁻¹)

10.16

Very mobile

K_foc (mL g⁻¹)

5.28

¹/_n

0.62

Notes and range

EU 2021 dossier K_f range 00.01-0.59 mL g⁻¹, K_foc range 2.0-23.7 mL g⁻¹, ¹/_n range 00.381-0.856, Soils=10

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.94

Calculated

Transition state

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

Value

3.93 X 10^-03

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Very mobile

Calculated

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

86.4

Calculated using the Atkinson method. Assumed 1.5E+06 OH/cm³, 12 hr

Substance of concern for long-range air transport

Bio-concentration factor

BCF (l kg⁻¹)

Low potential

CT₅₀ (days)

Not available

Known soil metabolites

Metabolite

Major/Minor fraction

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

Estimated maximum occurrence fraction

Notes

3,6-dichlorosalicylic acid (Ref: NOA 414746)

Major fraction

0.588

Known groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

2,5-dichloro-3-hydroxy-6-methoxybenzoic acid (Ref: NOA 405873)

5-hydroxy dicamba; 5-OH dicamba

Plant; Rat (Urine)

2,5-dichlorphenol

DCP

Animal

2-amino-3,6-dichlorophenol

Animal

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

1465

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

> 110

Rat 2 yr

Moderate

(ppm diet)

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

350

Unknown species Reproductive NOAEL

Low

Birds - Acute LD₅₀ (mg kg⁻¹)

188

Colinus virginianus

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

> 10000 mg kg feed⁻¹

Anas platyrhynchos

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

Anas platyrhynchos NOEL

Moderate

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

> 1000

Eisenia foetida

Low

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

51.25

Eisenia foetida

Moderate

Soil micro-organisms

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

Dose: 6.4 mg kg⁻¹ soil 28 Day

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

26.1

Folsomia candida

Non-target plants

Beta vulgaris
Seedling emergence, ER₅₀
as g ha⁻¹

Honeybees (Apis spp.)

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

> 89.5

Apis mellifera

Moderate

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

> 89.5

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

> 61.7

Apis mellifera

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

> 960

Chrysoperla carnea

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

356

Aphidius rhopalosiphi

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

232.6

Typhlodromus pyri

Beneficial insects (Ground beetles) as Mortality LR₅₀ g ha⁻¹

> 360

Poecilus cupreus

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

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

> 100

Cyprinus carpio

Low

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

180

Oncorhynchus mykiss

Low

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

> 98.85

Danio rerio

Moderate

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

> 41.0

Daphnia magna

Moderate

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

=> 97

Daphnia magna

Low

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

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

6.8

Mysidopsis 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)

32.0

Lemna gibba 14 day

Low

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

> 87

Pseudokirchneriella subcapitata

Low

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

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)

1465

Rat

Moderate

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

2000

Rabbit

Mammals - Inhalation LC₅₀ (mg l⁻¹)

4.46

Rat 4 hr (nose only)

Other Mammal toxicity endpoints

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

0.3

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

0.3

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

0.3

Rabbit SF=150

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

0.3

Dermal penetration studies (%)

0.1-6.0

concentrate dependent

Dangerous Substances Directive 76/464

Exposure Routes

Public

Negligible risk to bystanders

Occupational

No unacceptable risks to operators or other farm workers identified

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

0.1

EU Dir 89/778/EC limit

Mammalian dose elimination route and rate

Rapid and extensive elimination mainly via the urine

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

Eye irritant

Phototoxicant

General human health issues

Harmful if swallowed
Possible liver toxicant
May cause serious eye damage
Evidence of thyroid parafollicular (C-cell) carcinoma in male rats
May cause body weight effects

Handling issues

Property

Value and interpretation

General

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

CLP classification 2013

Health: H302, H318
Environment: H412

WHO Classification

II (Moderately hazardous)

UN Number

UN3077

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

Chemically stable under standard ambient conditions

TRANSLATIONS

Language

Name

English

dicamba

French

dicamba

German

Dicamba

Danish

dicamba

Italian

dicamba

Spanish

dicamba

Greek

dicamba

Polish

dikamba

Swedish

dikamba

Hungarian

dikamba

Dutch

dicamba

Norwegian

dikamba

Record last updated:	22/08/2024
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