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diquat
** diquat ion ** reglone ** reglon ** Translations

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SUMMARY

Diquat is an EU approved contact desiccant and herbicide that is normally used as the dibromide salt. As the salt 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. The dibromide salt is moderately toxic to mammals and is a known irritant but no other significant human health issues have been identified. The dibromide salt is moderately toxic to birds, most aquatic organisms, honeybees and earthworms.

GENERAL INFORMATION Click here for an explantaion of the general chemical status information
for diquat

Description: A non-residual bupyridyl herbicide and crop desiccant, normally used as the dibromide salt, 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: Current

Introduction & key dates: -

EC Regulation 1107/2009 (repealing 91/414):
Status Approved
Dossier rapporteur/co-rapporteur UK/Sweden
Date inclusion expires 30/06/2019
EU Candidate for substitution (CfS) Yes - low ADI / ARfD / AOEL; two 'Persistent-Bioaccumulative-Toxic' criteria
Listed in EU database Yes

Approved for use () or known to be used () in the following European countries: Click to access a note on the approvals information on this site

AT

BE

BG

CY

CZ

DE

DK

EE

EL

ES

FI

FR

HR

HU

IE

IT

LT

LU

LV

MT

NL

PL

PT

RO

SE

SI

SK

UK

Also used in: Australia

Chemical structure: Click here for further information on the general chemical status information used on this site
Isomerism -
Chemical formula C12H12N2
Canonical SMILES C1C[N+]2=CC=CC=C2C3=CC=CC=[N+]31
Isomeric SMILES No data
International Chemical Identifier key (InChIKey) SYJFEGQWDCRVNX-UHFFFAOYSA-N
International Chemical Identifier (InChI) InChI=1S/C12H12N2/c1-3-7-13-9-10-14-8-4-2-6-12(14)11(13)5-1/h1-8H,9-10H2/q+2
2D structure diagram/image available? Yes

Click to access the Cambridge Crystallographic Data Centre (CCDC) website
Cambridge Crystallographic Data Centre diagrams:
Common Name Relationship Link
Diquat dibromide Derivative Click here for the CCDC structure diagram

General status: Click here for further information on the general chemical status information used on this site
Pesticide type Herbicide
Substance group Bipyridylium
Minimum active substance purity -
Known relevant impurities -
Substance origin Synthetic
Mode of action Non-selective, contact absorbed through foliage, some desiccant action. Photosystem I (electron transport) inhibitor.
CAS RN 2764-72-9
EC number 220-433-0
CIPAC number 55
US EPA chemical code 032202
PubChem CID 6795
Molecular mass (g mol-1) 184.24
PIN (Preferred Identification Name) 6,7-dihydrodipyrido[1,2-a:2',1'-c]pyrazine-5,8-diium
IUPAC name 9,10-dihydro-8a,10a-diazoniaphenanthrene
CAS name 6,7-dihydrodipyrido[1,2-a:2',1'-c]pyrazinediium
Other status information Potential groundwater contaminant; PAN listed Highly Hazardous Chemical
Relevant Environmental Water Quality Standards -
Herbicide Resistance Classification (HRAC) D
Herbicide Resistance Classification (WSSA) 22
Insecticide Resistance Classification (IRAC) Not applicable
Fungicide Resistance Classification (FRAC) Note applicable
Examples of recorded resistance Monochoria korsakowii
Physical state Yellow crystalline solid
Related substances & organisms

Formulations:
Property Click here for information on the general product and branding information used on this site Value
Example manufacturers & suppliers of products using this active now or historically -
Example products using this active -
UK LERAP status None (may vary with mixtures)
Formulation and application details Normally formulated as the dibromide salt.


ENVIRONMENTAL FATE

for diquat

Property Click here for information on the parameters used to describe environmental fate on this site Value Source/Quality Score/Other Information Click here for information on the primary data sources used to populate this database with fate data Interpretation Click here for information on the way in which we interpret environmental fate data
Solubility - In water at 20oC (mg l-1) 718000 A5 High
Solubility - In organic solvents at 20oC (mg l-1) 25000 A5 - Methanol -
100 A5 - Acetone -
100 A5 - Hexane -
100 A5 - Ethyl acetate -
Melting point (oC) Decomposes before melting A5 -
Boiling point (oC) Decomposes before boiling A5 -
Degradation point (oC) - - -
Flashpoint (oC) - - -
Octanol-water partition coefficient at pH 7, 20oC P 2.51 X 10-05 Calculated -
Log P -4.6 A3 Low
Bulk density (g ml-1)/Specific gravity 1.61 A5 -
Dissociation constant (pKa) at 25oC - - -
Note:
Vapour pressure at 20oC (mPa) 1.00 X 10-03 A4 Low volatility
Henry's law constant at 25oC (Pa m3 mol-1) 5.0 X 10-12 A3 Non-volatile
GUS leaching potential index Click here for a note on the limitations of the GUS index -6.85 Calculated Low leachability
SCI-GROW groundwater index (μg l-1) for a 1 kg ha-1 or 1 l ha-1 application rate Click here for a note on the limitations of the SCI-GROW index Value 5.35 X 10-03 Calculated -
Note Estimated concentrations of chemicals with Koc values greater than 9995 ml g-1 are beyond the scope of the regression data used in SCI-GROW development. If there are concerns for such chemicals, a higher tier groundwater exposure assessment should be considered, regardless of the concentration returned by SCI-GROW
Potential for particle bound transport index Click here for a note on the limitations of the potential for particle bound transport index - Calculated High
Maximum UV-vis absorption L mol-1 cm-1 - - -
Surface tension (mN m-1) - - -

Degradation:
Property Click here for information on the parameters used to describe substance degradation Value Source/Quality Score/Other Information Click here for information on the primary data sources used to populate this database with degradation data Interpretation Click here for information on the way in which we interpret substance degradation data
General biodegradability -
Soil degradation (days) (aerobic) DT50 (typical) 2345 A5 Very persistent
DT50 (lab at 20oC) 2345 A5 Very persistent
DT50 (field) - - -
DT90 (lab at 20oC) 10478 A5 -
DT90 (field) - - -
DT50 modelling endpoint - - -
Note EU data lab studies DT50 range 598 to >1000 days, DT90 range from 1985 to 20509 days
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 7 A5 Moderately fast
Note -
Aqueous hydrolysis DT50 (days) at 20oC and pH 7 Value Stable A5 -
Note Stable at all environmentally relevant pH's
Water-sediment DT50 (days) >1000 A5 -
Water phase only DT50 (days) 1.0 A5 Moderately fast

Soil adsorption and mobility:
Property Click here for information on the parameters used to describe substance adsorption and mobility Value Source/Quality Score/Other Information Click here for information on the primary data sources used to populate this database with adsorption and mobility data Interpretation Click here for information on the way in which we interpret substance adsorption and mobility
Linear Kd - E4 Non-mobile
Koc 2185000
Notes and range Industry data
Freundlich Kf 23099 A5 Non-mobile
Kfoc 1078792
1/n 0.869
Notes and range EU dossier Kf range 144-70308 mL.g, Kfoc range 6857-2511015 mL/g, 1/n range 0.589-1065, soils=4
pH sensitivity No

Key metabolites:
Metabolite Formation medium Estimated maximum occurrence fraction 1107/2009 relevancy Click here for further information on 1107/2009 relevancy
1-oxo-1,2,3,4-tetrahydropyrido(1,2-a)pyrazin-5-ium (Ref: R32245) Soil   -   -

Other known metabolites:
Metabolite name and reference Aliases Formation medium / Rate Estimated maximum occurrence fraction Metabolising enzymes
1,2,3,4-tetrahydro-1-oxopyrido(1,2-a)pyrazin-5-ium
(Ref: R32245)
TOPPS Plant; Poultry; Eggs; Surface water (photolysis); Soil (minor) - -


ECOTOXICOLOGY

for diquat

Property Click here for information on the parameters used to describe substance ecotoxicology Value Source/Quality Score/Other Information Click here for information on the primary data sources used to populate this database with ecotoxicology data Interpretation Click here for information on the way in which we interpret substance ecotoxicology
Bio-concentration factor BCF (l kg-1) Low risk A5 Based on LogP < 3 Low potential
CT50 (days) - -
Mammals - Acute oral LD50 (mg kg-1) 214 A5 Rat Moderate
Mammals - Short term dietary NOEL (mg kg-1) 0.5 E4 Rat High
(ppm diet) - -
Birds - Acute LD50 (mg kg-1) 83 A5 Anas platyrhynchos High
Birds - Short term dietary (LC50/LD50) 721 mg kg feed-1 A5 Coturnix japonica -
Fish - Acute 96 hour LC50 (mg l-1) 21.0 A5 Oncorhynchus mykiss Moderate
Fish - Chronic 21 day NOEC (mg l-1) 0.12 A5 Oncorhynchus mykiss< Moderate
Aquatic invertebrates - Acute 48 hour EC50 (mg l-1) 1.2 A5 Daphnia magna Moderate
Aquatic invertebrates - Chronic 21 day NOEC (mg l-1) 0.125 A5 Daphnia magna Moderate
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) - - -
Non-target plants - - -
- - -
Algae - Acute 72 hour EC50, growth (mg l-1) 0.011 A5 Psuedokirchneriella subcapitata Moderate
Algae - Chronic 96 hour NOEC, growth (mg l-1) - - -
Honeybees Contact acute 48 hour LD50 (μg bee-1) 60 A5 as diquat ion Moderate
Oral acute 48 hour LD50 (μg bee-1) 13 A5 as diquat ion Moderate
Unknown mode acute 48 hour LD50 (μg bee-1) - - -
Earthworms - Acute 14 day LC50 (mg kg-1) 94.3 A5 Eisenia foetida Moderate
Earthworms - Chronic 14 day NOEC, reproduction (mg kg-1) - - -
Other soil macro-organisms - e.g. Collembola LR50 / EC50 / NOEC / % Effect - - -
Other arthropod (1) LR50 g ha-1 - - -
% Effect - - -
Other arthropod (2) LR50 g ha-1 - - -
% Effect - - -
Soil micro-organisms Nitrogen mineralisation: No significant adverse effect
Carbon mineralisation: No significant adverse effect
A5
Dose: >160 mg kg-1 soil
-
Mesocosm study data NOEAEC mg l-1 - - -
NOEAEC mg l-1 - - -


HUMAN HEALTH AND PROTECTION

for diquat

General:
Property Click here for information on the parameters used to describe human health and protection issues Value Source/Quality Score/Other Information Click here for information on the primary data sources used to populate this database with human health and protection data Interpretation Click here for information on the way in which we interpret human health and protection data
Threshold of Toxicological Concern (Cramer Class) Click here for a note on the limitations of the Cramer class High (class III) - -
Mammals - Acute oral LD50 (mg kg-1) 214 A5 Rat Moderate
Mammals - Dermal LD50 (mg kg-1 body weight) > 400 V3 Rat -
Mammals - Inhalation LC50 (mg l-1) - - -
Other Mammal toxicity endpoints - -
ADI - Acceptable Daily Intake (mg kg-1bw day-1) 0.002 A5 -
ARfD - Acute Reference Dose (mg kg-1bw day-1) None allocated A5 -
AAOEL - Acute Acceptable Operator Exposure Level (mg kg-1 bw day-1) - - -
AOEL - Acceptable Operator Exposure Level - Systemic (mg kg-1bw day-1) 0.001 A5 -
Dermal penetration studies (%) - - -
Dangerous Substances Directive 76/464 - - -
Exposure Limits - - -
Exposure Routes Public Slight risk of dietary exposure
Occupational -
European MRLs Click here for the EU MRL pesticide database
Drinking Water Standards - - -
Drinking Water MAC (μg l-1) - - -

Health issues:
Carcinogen Mutagen Endocrine disrupter Reproduction / development effects Cholinesterase inhibitor Neurotoxicant

-

-

Respiratory tract irritant Skin irritant Skin sensitiser Eye irritant Phototoxicant

-

General human health issues Potential liver, kidney, stomach and intestine toxicant

: Yes, known to cause a problem
: No, known not to cause a problem
: Possibly, status not identified
- : No data found

Handling issues:
Property Click here for information on the parameters used to describe substance handling issues Value Source/Quality Score/Other Information Click here for information on the primary data sources used to populate this database with data on handling issues Interpretation Click here for information on the way in which we interpret data on handling issues
General Click here for a description of the International Maritime Dangerous Goods (IMDG) codes IMDG Transport Code is usually 8
CLP classification 2013 Health: H335, H302, H317, H330, H372, H315, H319
Environment: H400, H410
EC Risk Classification Click here to view information omn the EU risk phrases T+ - Very toxic: R26
T - Toxic: R48/25
Xn - Harmful: R22, R43
Xi - Irritant: R36/37/38
N - Dangerous for the environment: R50, R53
EC Safety Classification Click here to view information omn the EU safety phrases S1/2, S28, S36/37/39, S45, S60, S61
WHO Classification II - Moderately hazardous
US EPA Classification (formulation) II - Warning - Moderately toxic
UN Number 2781 as active, products usually 1760
Waste disposal & packaging Click here for a description of UN packaging marks Packaging Group III (minor danger)


TRANSLATIONS

for diquat

Language Name
English diquat
French diquat
German Deiquat
Danish diquat
Italian diquat
Spanish dicuat
Greek diquat
Slovenian dikvat
Polish dikwatu
Swedish dikvat
Hungarian diquat
Dutch diquat

Record last updated: Wednesday 31 October 2018
Contact: aeru@herts.ac.uk
© University of Hertfordshire