Diquat dichloride-Pesticide database

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Diquat dichloride

(Also known as: diquat; deiquat; reglone)

Diquat dibromide is a contact desiccant and herbicide. It is highly soluble in water, has a low risk of leaching to groundwater and is volatile. It is very persistent in soil but rapidly degrades in aquatic systems. It is moderately toxic to mammals and is a known irritant but no other significant human health issues have been identified. It is moderately toxic to birds, most aquatic organisms, honeybees and earthworms.

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: Very persistent Warning: Significant data are missing		Human health Moderate alert: Mammals acute toxicity: Moderate

GENERAL INFORMATION

A non-residual bupyridyl herbicide and crop desiccant used mainly to control broad-leaved weeds and grasses

Example pests controlled

Water lettuce; Water hyacynth; Duckweed; Pennywort; Annual bluegrass; Fescue; Henbit; Buttercup

Example applications

Potatoes; Oilseed rape; Fruit including apples, pears, peaches, plums, citrus, olive, grapes; Tomatoes; Sunflowers; Vegetables including beans & peas, carrots, onions, chicory; Sugarbeet

Efficacy & activity

Availability status

Introduction & key dates

1958, first reported

UK regulatory status

UK COPR regulatory status

Date COPR inclusion expires

UK LERAP status

No UK approval for use

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Dossier rapporteur/co-rapporteur

Date EC 1107/2009 inclusion expires

EU Candidate for substitution (CfS)

Listed in EU database

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

Chemical structure

Chemical formula

C₁₂H₁₂Cl₂N₂

Canonical SMILES

Isomeric SMILES

International Chemical Identifier key (InChIKey)

SKYNPRKUXHXZFJ-UHFFFAOYSA-L

International Chemical Identifier (InChI)

InChI=1S/C12H12N2.2ClH/c1-3-7-13-9-10-14-8-4-2-6-12(14)11(13)5-1;;/h1-8H,9-10H2;2*1H/q+2;;/p-2

2D structure diagram/image available?

Substance groups

Quarternary ammonium herbicide

Minimum active substance purity

Known relevant impurities

EU dossier - dibromoethane; 2,2-bipyridine; terpyridine & related isomers

Substance origin

Non-selective, contact absorbed through foliage, some desiccant action. Photosystem I (electron transport) inhibitor.

US EPA chemical code

CLP index number

PIN (Preferred Identification Name)

6,7-dihydrodipyrido[1,2-a:2′,1′-c]pyrazine-5,8-diium dichloride

9,10-dihydro-8a,10a-diazoniaphenanthrene dichloride

6,7-dihydrodipyrido[1,2-a:2′,1′-c]pyrazinediium dichloride

Other status information

Potential groundwater contaminant; PAN listed Highly Hazardous Chemical

Relevant Environmental Water Quality Standards

Herbicide Resistance Classification (HRAC)

Herbicide Resistance Classification (WSSA)

Insecticide Resistance Classification (IRAC)

Fungicide Resistance Classification (FRAC)

Examples of recorded resistance

Crystalline solid

Related substances & organisms

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

AgriGuard
Clayton
Standon
Syngenta
ICI Plant Protection

Example products using this active

Reglone
Retro
Quad
Googly
Weedol
Reglox

Formulation and application details

Often supplied as a soluble concentrate, gel or liquid concentrate

ENVIRONMENTAL FATE

Source; quality score; and other information

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

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

Melting point (°C)

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

Fat solubility of residues

Density (g ml⁻¹)

Dissociation constant pKa) at 25 °C

A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes

No dissociation

Vapour pressure at 20 °C (mPa)

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

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

Surface tension (mN m⁻¹)

Source; quality score; and other information

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

DT₅₀ (lab at 20 °C)

DT₅₀ (field)

A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data

Very persistent

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

DT₅₀ modelling endpoint

Dissipation rate RL₅₀ on plant matrix

Dissipation rate RL₅₀ on and in plant matrix

Aqueous photolysis DT₅₀ (days) at pH 7

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

A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes

Stable pH 5 to pH 9

Water-sediment DT₅₀ (days)

Water phase only DT₅₀ (days)

Soil adsorption and mobility

Source; quality score; and other information

Notes and range

Notes and range

Source; quality score; and other information

GUS leaching potential index

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

Cannot be calculated

Potential for particle bound transport index

Potential for loss via drain flow

Bio-concentration factor

BCF (l kg⁻¹)

CT₅₀ (days)

Known soil metabolites

Major/Minor fraction

Estimated maximum occurrence fraction

1-oxo-1,2,3,4-tetrahydropyrido(1,2-a)pyrazin-5-ium (Ref: R32245)

Known groundwater metabolites

None

Other known metabolites

None

Terrestrial ecotoxicology

Source; quality score; and other information

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes

Mammals - Short term dietary NOEL

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

Birds - Acute LD₅₀ (mg kg⁻¹)

Birds - Short term dietary (LC₅₀/LD₅₀)

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

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

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

Soil micro-organisms

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Non-target plants

Honeybees (Apis 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)

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 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)

Beneficial insects (Parasitic wasps)

Beneficial insects (Predatory mites)

Beneficial insects (Ground beetles)

Aquatic ecotoxicology

Source; quality score; and other information

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

Fish - Chronic 21 day NOEC (mg l⁻¹)

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

Aquatic invertebrates - Chronic 21 day NOEC (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)

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

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

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

Mesocosm study data

NOEAEC mg l⁻¹

NOEAEC mg l⁻¹

HUMAN HEALTH AND PROTECTION

Source; quality score; and other information

Threshold of Toxicological Concern (Cramer Class)

High (class III)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes

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

A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes

Mammals - Inhalation LC₅₀ (mg l⁻¹)

A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes

Other Mammal toxicity endpoints

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

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

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

Exposure Routes

EU MRL pesticide database

GB MRL Register

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

Mammalian dose elimination route and rate

Specific human health issues

Endocrine disruptor

XNo, known not to cause a problem

A3 A = Chromosome aberration (EFSA database)
3 = Negative

B3 B = DNA damage/repair (EFSA database)
3 = Negative

C3 C = Gene mutation (EFSA database)
3 = Negative

D0 D = Genome mutation (EFSA database)
0 = No data

E3 E = Unspecified genotoxicity type (miscellaneous data source)
3 = Negative

XNo, known not to cause a problem

Reproduction / development effects

Acetyl cholinesterase inhibitor

XNo, known not to cause a problem

XNo, known not to cause a problem

XNo, known not to cause a problem

Respiratory tract irritant

Skin sensitiser

✓Yes, known to cause a problem

✓Yes, known to cause a problem

✓Yes, known to cause a problem

✓Yes, known to cause a problem

General human health issues

Potential liver, kidney, stomach and intestine toxicant
Fatal if inhaled

Handling issues

Value and interpretation

IMDG Transport Hazard Class 6.1
Corrosive to most metals & may form flammable and explosive H2 gas when in contact with aluminum
May decompose at high temperatures to form toxic gases

CLP classification 2013

Health: H302, H315,H317, H319, H330, H335, H372
Environment: H400, H410

WHO Classification

II (Moderately hazardous)

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

diquat dichloride

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