Cyhalofop-butyl (Ref: DE 537)

Cyhalofop-butyl (Ref: DE 537)	Last updated: 12/01/2021
(Also known as: XDE 537; XRD 537)

GENERAL INFORMATION

Description

A selective herbicide used for post-emergence control of grass weeds usually in rice crops

Example pests controlled

Barnyardgrass; Silver top; Rice flatsedge; Arrowhead; Junglerice; Pigweed; Cocklebur

Example applications

Rice

Efficacy & activity

Availability status

Current

Introduction & key dates

circa 1990, Asia

UK regulatory status

UK COPR regulatory status

Not approved

Date COPR inclusion expires

Not applicable

UK LERAP status

No UK approval for use

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

Italy/Austria

Date EC 1107/2009 inclusion expires

30/06/2032

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
				✓

Also used in

Australia

Chemical structure

Isomerism

A chiral molecule in which the R-isomer is by far the most dominant and often accounts for over 95% of cyhalofop-butyl

Chemical formula

C₁₆H₁₂FNO₄

Canonical SMILES

CCCCOC(=O)C(C)OC1=CC=C(C=C1)OC2=C(C=C(C=C2)C#N)F

Isomeric SMILES

CCCCOC(=O)[C@@H](C)OC1=CC=C(C=C1)OC2=C(C=C(C=C2)C#N)F

International Chemical Identifier key (InChIKey)

TYIYMOAHACZAMQ-CQSZACIVSA-N

International Chemical Identifier (InChI)

InChI=1S/C20H20FNO4/c1-3-4-11-24-20(23)14(2)25-16-6-8-17(9-7-16)26-19-10-5-15(13-22)12-18(19)21/h5-10,12,14H,3-4,11H2,1-2H3/t14-/m1/s1

2D structure diagram/image available?

Yes

General status

Pesticide type

Herbicide

Substance group

Aryloxyphenoxypropionate

Minimum active substance purity

950 g kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

Systemic, foliar untake with no soil activity. ACCase inhibitor.

CAS RN

122008-85-9

EC number

CIPAC number

596

US EPA chemical code

082583

PubChem CID

180089

Molecular mass

357.38

PIN (Preferred Identification Name)

butyl (2R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propanoate

IUPAC name

butyl (R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propionate

CAS name

butyl (2R)-2-(4-(4-cyano-2-fluorophenoxy)phenoxy)propanoate

Other status information

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

Echinochloa crus-galli

Physical state

White crystalline solid

Related substances & organisms

cyhalofop

Formulations

Property

Value

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

Beauty
Frog
Clincher
Rebelex

Example products using this active

Dow AgroSciences
Fertiagro Pte. Ltd.

Formulation and application details

Usually supplied as an emulsifiable concentrate

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

0.44

Low

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

6060

n-Heptane

250000

Xylene

250000

Acetone

250000

Methanol

Melting point (°C)

45.5

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

270

Flashpoint (°C)

122

(open cup)

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

2.09 X 10⁰³

Calculated

Log P

3.32

High

Bulk density (g ml⁻¹)

1.17

Dissociation constant pKa) at 25 °C

Vapour pressure at 20 °C (mPa)

0.053

at 25°C

Low volatility

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

9.51 X 10^-04

Non-volatile

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

In MeOH: 247.8nm = 16100, 233.4nm = 15900, 202.6nm = 32700
In 1M HCl in MeOH: 247.6nm = 16400, 233.4nm 16400, 202.2nm = 37000, 236.0nm = 17100, 211.6nm = 12300

Surface tension (mN m⁻¹)

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

0.2

Non-persistent

DT₅₀ (lab at 20 °C)

0.2

Non-persistent

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

EU dossier lab studies DT₅₀ range 0.24-0.85 days, DT₉₀ range 0.8-2.8 days; Other sources: 1.0 day (DW4)

Dissipation rate RL₅₀ on plant matrix

Value

Note

Dissipation rate RL₅₀ on and in plant matrix

Value

4.3

Note

Published literature RL₅₀ range 2.1-8.7 days, 2 field crops, various matrices, n=3

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Slow

Note

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

Value

Moderately persistent

Note

Stable at pH 4, DT₅₀ 2 days at pH 9, 25 °C

Water-sediment DT₅₀ (days)

0.1

Fast

Water phase only DT₅₀ (days)

0.15

Fast

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

Non-mobile

K_oc

5247

Notes and range

EU dossier K_oc range 2066-9637 ml/g

Freundlich

K_f

41.5

Slightly mobile

K_foc

1016

¹/_n

0.878

Notes and range

EU dossier K_f range 11.9-72.3 mL g⁻¹; K_foc range 512-2079 mL g⁻¹, ¹/_n range 0.833-0.960, Soils=5

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

-0.69

Calculated

Low leachability

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

Value

9.96 X 10^-06

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Non-mobile

Calculated

Key metabolites

Metabolite

Formation medium

Estimated maximum occurrence fraction

1107/2009 relevancy

cyhalofop

Soil

0.958

Major fraction, Relevant

cyhalofop amide

Soil

0.081

Major fraction, Relevant

cyhalofop diacid (Ref: XDE-537 )

Soil

0.865

Major fraction, Relevant

ECOTOXICOLOGY

Property

Value

Source; quality score; and other information

Interpretation

Bio-concentration factor

BCF (l kg⁻¹)

7.5

Low potential

CT₅₀ (days)

Not available

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 5000

Rat

Low

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat

High

(ppm diet)

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

Birds - Acute LD₅₀ (mg kg⁻¹)

> 2250

Colinus virginianus

Low

Birds - Short term dietary (LC₅₀/LD₅₀)

> 5620 mg kg feed⁻¹

Colinus virginianus

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

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

0.79

Lepomis macrochirus

Moderate

Fish - Chronic 21 day NOEC (mg l⁻¹)

0.13

Oncorhynchus mykiss

Moderate

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

> 2.7

Daphnia magna

Moderate

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

100

Daphnia magna

Low

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)

> 5.3

Lemna minor

Moderate

Non-target plants

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

> 0.96

Scenedemus subspicatus

Moderate

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)

> 100

Low

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

> 100

Low

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)

> 1000

Low

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

Other soil macro-organisms

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Other arthropod (1)

LR₅₀ g ha⁻¹

% Effect

100

Mortality [Dose: 0.3 kg ha⁻¹]
Aphidius rhopalosiphi adult

Other arthropod (2)

LR₅₀ g ha⁻¹

% Effect

Mortality [Dose: 0.3 kg ha⁻¹]
Typhlodromus pyri protonymph

Soil micro-organisms

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

Dose: 1.5 kg ha⁻¹ 28 days

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)

> 5000

Rat

Low

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 5.63

Rat 4 hr (dust; whole body)

Other Mammal toxicity endpoints

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

0.003

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

None 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)

0.03

Mouse 90 day SF=100

Dermal penetration studies (%)

1.0-23.0

concentration dependent

Dangerous Substances Directive 76/464

Exposure Routes

Public

Occupational

Risk of exposure acceptable under label recommendations for use for personal protection clothing and equipment

European MRLs

EU MRL pesticide database

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

Potential gall bladder, liver & kidney toxicant

Handling issues

Property

Value and interpretation

General

Not explosive or oxidising

CLP classification 2013

Health: H302, H373
Environment: H400, H410

EC Risk Classification

EC Safety Classification

S61

WHO Classification

U (Unlikely to present an acute hazard)

UN Number

Waste disposal & packaging

TRANSLATIONS

Language

Name

English

cyhalofop-butyl

French

cyhalofop-butyl

German

Cyhalofop-butyl

Danish

cyhalofop-butyl

Italian

cyhalofop-butyl

Spanish

cihalofop-butil

Greek

Polish

cyhalofop butylowy

Swedish

Hungarian

Dutch

Record last updated:	12/01/2021
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