Imazaquin (Ref: BAS 725H)

Imazaquin (Ref: BAS 725H)	Last updated: 29/08/2024
(Also known as: AC 252214; CL 252214)

SUMMARY

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: Mobile	Ecotoxicity High alert: Earthworms chronic ecotoxicity: High	Human health Moderate alert: Reproduction/development effects

GENERAL INFORMATION

Description

Used as pre- and post-emergence particularly for the control of grasses and broad-leaved weeds

Example pests controlled

Annual grasses and broad-leaved weeds

Example applications

Soybeans; Ornamentals; Turf

Efficacy & activity

Availability status

Current

Introduction & key dates

1986, registered USA

GB regulatory status

GB COPR regulatory status

Not approved

Date COPR inclusion expires

Expired

GB LERAP status

No UK approval for use as a pesticide

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Not approved

Dossier rapporteur/co-rapporteur

Not applicable

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

Chemical structure

Isomerism

A chiral molecule, imazaquin is an isomeric mixture of the R- and S-forms

Chemical formula

C₁₇H₁₇N₃O₃

Canonical SMILES

CC(C)C1(C(=O)NC(=N1)C2=NC3=CC=CC=C3C=C2C(=O)O)C

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

CABMTIJINOIHOD-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C17H17N3O3/c1-9(2)17(3)16(23)19-14(20-17)13-11(15(21)22)8-10-6-4-5-7-12(10)18-13/h4-9H,1-3H3,(H,21,22)(H,19,20,23)

2D structure diagram/image available?

Yes

General status

Pesticide type

Herbicide, Plant Growth Regulator

Substance groups

Imidazolinone herbicide

Minimum active substance purity

960 g kg⁻¹ racemic mixture

Known relevant impurities

EU dossier - Hydrogen cyanide, Toluene

Substance origin

Synthetic

Mode of action

Selective, systemic absorbed by roots and foliage. Inhibits plant amino acid synthesis - acetohydroxyacid synthase AHAS.

CAS RN

81335-37-7

EC number

617-220-3

CIPAC number

699

US EPA chemical code

128840

PubChem CID

54739

CLP index number

No data found

Molecular mass

311.33

PIN (Preferred Identification Name)

IUPAC name

2-[(RS)-4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl]quinoline-3-carboxylic acid

CAS name

2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl)-3-quinolinecarboxylic acid

Other status information

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

Many recorded cases, Amaranthus hybridus, Amaranthus palmeri, Amaranthus powellii

Physical state

Grey fine crystalline solid

Related substances & organisms

imazaquin ammonium

imazaquin methyl

imazaquin sodium

Formulations

Property

Value

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

BASF
Standon
AgroCare

Example products using this active

Meteor
Upright
Scepter

Formulation and application details

Usually supplied as a soluble concentrate that is mixed with water and applied as a spray but also available as dispersible granules

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

102000

High

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

240

Toluene

14500

Dichloromethane

3690

Acetone

1490

Ethyl acetate

Melting point (°C)

224

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

250

Flashpoint (°C)

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

8.13 X 10^-02

Calculated

Log P

-1.09

Low

Fat solubility of residues

Solubility

Insoluble

Data type

Regulatory data

Density (g ml⁻¹)

0.41

Dissociation constant pKa) at 25 °C

3.45

Weak acid, Pka(2) 11.03

Vapour pressure at 20 °C (mPa)

7.0 X 10^-10

Low volatility

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

3.74 X 10^-12

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

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

Surface tension (mN m⁻¹)

49.9

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)

106.6

Persistent

DT₅₀ (field)

4.3

Non-persistent

DT₉₀ (lab at 20 °C)

354.2

Persistent

DT₉₀ (field)

36.5

DT₅₀ modelling endpoint

Note

EU dossier aerobic lab studies DT₅₀ range 43-223 days (normalised), DT₉₀ range 143-742 days (normalised); field studies DT₅₀ range 1.7-12 days (normalised), DT₉₀ range 5-103 days (normalised); Other sources: Lab studies showed slow degradation (B5)

Dissipation rate RL₅₀ (days) on plant matrix

Value

Note

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

13.1

Note

Published literature RL₅₀ range 4.4-39.8 days, 6 field crops, various matrices, n=8

Aqueous photolysis DT₅₀ (days) at pH 7

Value

0.75

Fast

Note

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

Value

Stable

Note

Stable pH 4 to pH 7, DT₅₀ 169 days at pH 9 and 25 °C, 20.6 days at pH 9 and 50 °C

Water-sediment DT₅₀ (days)

475

Stable

Water phase only DT₅₀ (days)

194

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)

0.31

Mobile

K_foc (mL g⁻¹)

17.96

¹/_n

1.03

Notes and range

EU dossier kf range 0.114-0.316, K_foc range 8.9-37 mL g⁻¹, ¹/_n range 0.993-1.11, Soils=5

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.74

Calculated

Low leachability

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

Value

3.88 X 10^-03

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Mobile

Calculated

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

5.86

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

Below the level of concern for long-range air transport

Bio-concentration factor

BCF (l kg⁻¹)

0.39

Estimated

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

2-(1-carbamoyl-1,2-dimethyl-propylcarbamoyl)-quinoline-3-carboxylic acid (Ref: CL 266066)

Minor fraction

0.054

3-quinoline carboxylic acid

Minor fraction

2,3-quinoline di-carboxylic acid (Ref: CL 263875)

Minor fraction

Known groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

2,3-quinoline di-carboxylic acid-3-methylester

Plant

2,3-quinoline di-carboxylic acid (Ref: CL 263875)

Plant

2,3-quinoline di-carboxylic acid-2-methylester

Plant

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)

> 474

Rat

Moderate

(ppm diet)

> 10000

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

> 917

Rat Reproductive NOAEL

Low

Birds - Acute LD₅₀ (mg kg⁻¹)

> 2150

Anas platyrhynchos

Low

Birds - Short term dietary (LC₅₀/LD₅₀)

> 1166 mg kg bw⁻¹ day⁻¹

Colinus virginianus

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

16.6

Colinus virginianus

Moderate

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

> 23.5

Eisenia foetida

Moderate

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

> 0.028

Eisenia foetida

High

Soil micro-organisms

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

Dose: 0.0133 mg kg⁻¹ soil 28 Day

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Non-target plants

> 1.7

Allium cepa
Seedling emergence, ER₅₀
as L product ha⁻¹ (Meteor)

> 1.8

Beta vulgaris
Vegetative vigour, ER₅₀
as L product ha⁻¹ (Meteor)

Honeybees (Apis spp.)

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

> 100

Apis mellifera

Low

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

> 6.5

Apis mellifera

Moderate

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

Chronic

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) as Mortality LR₅₀ g ha⁻¹

> 4.0

Aphidius rhopalosiphi

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

> 4.0

Typhlodromus pyri

Beneficial insects (Ground beetles)

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

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

> 100

Oncorhynchus mykiss

Low

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

51.2

Oncorhynchus mykiss

Low

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

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

> 100

Daphnia magna

Low

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

100

Daphnia magna

Low

Tropical Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (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)

228

Chironomus riparius Emergence

Low

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

0.031

Lemna gibba

Moderate

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

21.5

Pseudokirchneriella subcapitata

Low

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

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)

> 5000

Rat

Low

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

5000

Rabbit

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 5.7

Rat 4 hr (whole body)

Other Mammal toxicity endpoints

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

0.25

Dog SF=100

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

Not allocated

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

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

0.25

Dog SF=100

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

Exposure Routes

Public

Negligible risks to bystanders

Occupational

No unacceptable risks identified for operators or other farm workers

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

EU expected to amend imazaquin MRL in early 2023

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

Mammalian dose elimination route and rate

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

No data found

General human health issues

Harmful if ingested

Handling issues

Property

Value and interpretation

General

Not explosive or oxidising
Not expected to auto-ignite; Not highly flammable

CLP classification 2013

Health: H302, H317, H319
Environment: H401

WHO Classification

U (Unlikely to present an acute hazard)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

imazaquin

French

imazaquine

German

Imazaquin

Danish

imazaquin

Italian

imazaquin

Spanish

imazaquin

Greek

Polish

imazachin

Swedish

Hungarian

imazaquin

Dutch

Norwegian

Record last updated:	29/08/2024
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