Cycloxydim (Ref: BAS 517H)

Cycloxydim (Ref: BAS 517H)	Last updated: 23/05/2025
(Also known as: cycloxydime; LAB 172 999)

SUMMARY

Cycloxydim is a systemic herbicide. It is moderately soluble in aqueous solution, is unlikely to leach to groundwater and is relatively volatile. It is not persistent in soils and is unlikely to persist in aquatic systems due to rapid aqueous photolysis. It has a low mammalian toxicity and, whilst the chemical properties suggest it may bioaccumulate, that does not appear to happen in practice. It is a skin and eye irritant. It is moderately toxic to birds, honeybees, earthworms and aquatic invertebrates. However, its is not particularly toxic to fish or other aquatic organisms.

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 Moderate alert: Birds chronic ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate; Earthworms acute ecotoxicity: Moderate	Human health Moderate alert: Mammals chronic toxicity: Moderate; Reproduction/development effects

GENERAL INFORMATION

Description

A post-emergence foliar applied grass herbicide

Example pests controlled

Blackgrass; Volunteer cereals; Black bent; Onion couch

Example applications

Sugarbeet; Fodder beet; Mangels; Linseed; Vegetables including brassicas, beans, peas, leeks, carrots, swede; Fruit including strawberries; Potatoes

Efficacy & activity

Availability status

Current

Introduction & key dates

1989, registered France

GB regulatory status

GB COPR regulatory status

Approved

Date COPR inclusion expires

31/05/2026

GB LERAP status

None

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

Netherlands/Denmark

Date EC 1107/2009 inclusion expires

31/08/2026

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

Morocco

Chemical structure

Isomerism

A chiral molecule existing in both the E- and the Z-forms depending on the polarity and the pH of the respective environment in which the molecule sits. The Z-isomer is predominate in acidic situations.

Chemical formula

C₁₇H₂₇NO₃S

Canonical SMILES

CCCC(=C1C(=O)CC(CC1=O)C2CCCSC2)NOCC

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

GGWHBJGBERXSLL-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C17H27NO3S/c1-3-6-14(18-21-4-2)17-15(19)9-13(10-16(17)20)12-7-5-8-22-11-12/h12-13,19H,3-11H2,1-2H3/b18-14-

2D structure diagram/image available?

Yes

General status

Pesticide type

Herbicide

Substance groups

Cyclohexanedione herbicide; Cyclohexene oxime herbicide

Minimum active substance purity

940 g kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

Selective, systemic, absorbed by foliage. Acetyl CoA carboxylase inhibitor (ACCase) - distrupts fatty acid biosynthesis and lipid formation.

CAS RN

101205-02-1

EC number

405-230-9

CIPAC number

510

US EPA chemical code

PubChem CID

91765

CLP index number

606-147-00-2

Molecular mass

325.46

PIN (Preferred Identification Name)

(5E)-2-[(1E)-N-ethoxybutanimidoyl]-3-hydroxy-5-[(3E)-thian-3-yl]cyclohex-2-en-1-one

IUPAC name

(5RS)-2-[(EZ)-1-(ethoxyimino)butyl]-3-hydroxy-5-[(3RS)-thian-3-yl]cyclohex-2-en-1-one

CAS name

2-[1-(ethoxyimino)butyl]-3-hydroxy-5-(tetrahydro-2H-thiopyran-3-yl)-2-cyclohexen-1-one

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

Alopecurus myosuroides, Avena sterilis

Physical state

Colourless crystals

Formulations

Property

Value

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

BASF
Greencrop
Teliton

Example products using this active

Focus 10 EC
Laser
Focus Ultra
Stratos Ultra

Formulation and application details

Often supplied as an emulsion concentrate which is mixed with water and applied as a spray to dry foliage

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

Moderate

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

250000

Acetone

810000

Ethanol

29000

Hexane

250000

Ethyl acetate

Melting point (°C)

37.1

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

200

Flashpoint (°C)

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

2.29 X 10⁰¹

Calculated

Log P

1.36

Low

Fat solubility of residues

Solubility

Insoluble

Data type

Regulatory data - cycloxydim not present in plants and no metabolite accumulation seen in fat

Density (g ml⁻¹)

1.12

Dissociation constant pKa) at 25 °C

4.17

Weak acid

Vapour pressure at 20 °C (mPa)

0.01

Low volatility

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

6.14 X 10^-05

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

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

Neutral solution: >290nm = 10
Methanol: 210nm = 7200, 227nm = 4100, 259nm = 1000, 278nm = 9300, 290nm = 7900, 300nm = 4400

Surface tension (mN m⁻¹)

58.0

at 20°C 0.5%w/w

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

0.65

Non-persistent

DT₅₀ (lab at 20 °C)

0.65

Non-persistent

DT₅₀ (field)

Non-persistent

DT₉₀ (lab at 20 °C)

3.47

Non-persistent

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

EU Dossier lab studies DT₅₀ range 0.2-2.6 days, DT₉₀ range 0.5-8.6 days; Other lab studies DT₅₀ 1-12 days

Dissipation rate RL₅₀ (days) on plant matrix

Value

Note

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

Note

Aqueous photolysis DT₅₀ (days) at pH 7

Value

0.05

Fast

Note

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

Value

172

Persistent

Note

pH sensitive: DT₅₀ 1.7 days at pH 3, 8.3 days at pH 5, 172 days at pH 7, 206 days at pH 9 all at 24 °C

Water-sediment DT₅₀ (days)

20.8

Fast

Water phase only DT₅₀ (days)

4.5

Moderately fast

Sediment phase only DT₅₀ (days)

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)

0.38

Mobile

K_oc (mL g⁻¹)

Notes and range

EU dossier K_d range 0.03-0.73 mL g⁻¹, K_oc range 5-183 mL g⁻¹, Soils=4; Other studies 5-185 mL g⁻¹

Freundlich

K_f (mL g⁻¹)

K_foc (mL g⁻¹)

¹/_n

Notes and range

pH sensitivity

None but little adsorption observed on soils pH >6

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.56

Calculated

Low leachability

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

Value

4.19 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

2.1

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)

Low risk

Based on LogP < 3

Low risk

CT₅₀ (days)

No data

Known soil metabolites

Metabolite

Major/Minor fraction

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

Estimated maximum occurrence fraction

Notes

cycloxydim sulfoxide (Ref: BH 517-TSO)

Major fraction

0.904

cycloxydim sulfone (Ref: BH 517-TSO2)

Minor fraction

0.095

2-propyl-6-(3-thianyl)-4,5,6,7-tetrahydrobenzoxazol-4-one S-dioxide (Ref: BH 517-T2SO2)

Minor fraction

0.099

3-(1-oxidotetrahydro-2H-thiopyran-3-yl)pentanedioic acid (Ref: BH 517-TGSO)

Minor fraction

Known groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

2-butanimidoyl-3-hydroxy-5-(1-oxidotetrahydro-2H-thiopyran-3-yl)cyclohex-2-en-1-one (Ref: BH 517-T1SO)
Note: Low aquatic toxicity

Animal; Surface water; Sediment

2-propyl-6-(3-thianyl)-4,5,6,7-tetrahydrobenzoxazol-4-one S-dioxide (Ref: BH 517-T2SO2)

cycloxydim oxazole metabolite

Plant

3-(1-oxidotetrahydro-2H-thiopyran-3-yl)pentanedioic acid (Ref: BH 517-TGSO)

Plant

3-(3-thianyl)glutaric acid S- dioxide (Ref: BH 517-TGSO2)

Plant

3-hydroxy-3-(3-thianyl)glutaric acid S-dioxide (Ref: BH 517-OH-TGSO2)

Plant

2-butanimidoyl-5-(1,1-dioxidotetrahydro-2H-thiopyran-3-yl)-3-hydroxycyclohex-2-en-1-one (Ref: BH 517-T1SO2)

Plant

2-[1-(ethoxyimino)butyl]-3,5-dihydroxy-5-(3-thianyl)-2-cyclohexen-1-one (Ref: BH 517-5-OH TS)

Plant

2-[1-(ethoxyimino)butyl]-3,5-dihydroxy-5-(3-thianyl)-2-cycloexene-1-one S-oxide (Ref: BH 517-5-OH-TSO)

Plant

2-[1-(ethoxyimino)butyl]-3,5-dihydroxy-5-(3-thianyl)-2-cycloexene-1-one S-dioxide (Ref: BH 517-5-OH-TSO2)

Plant

2-propyl-6-(3-thianyl)-4,5,6,7-tetrahydrobenzoxazol-4-one S-oxide (Ref: BH 517-6-OH-T2SO)

Plant

2-propyl-6-(3-thianyl)-4,5,6,7-tetrahydrobenzoxazol-4-one (Ref: BH 517-T2S)

cycloxydim oxazole metabolite

Plant; Surface water

2-butanimidoyl-3-hydroxy-5-(tetrahydro-2H-thiopyran-3-yl)cyclohex-2-en-1-one (Ref: BH 517-T1S)
Note: Low aquatic toxicity

Surface water; Sediment; Animal

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

3940

Rat

Low

Mammals - Short term dietary NOEL

(mg kg⁻¹)

> 10

Dog

High

(ppm diet)

> 300

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

129

Unknown species Reproductive NOAEL

Moderate

Birds - Acute LD₅₀ (mg kg⁻¹)

> 2000

Colinus virginianus

Low

Birds - Short term dietary (LC₅₀/LD₅₀)

496.8 mg kg bw⁻¹ day⁻¹

Colinus virginianus

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

65.4

Colinus virginianus

Moderate

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

> 500

Eisenia foetida corr

Moderate

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

Soil micro-organisms

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

Dose: 2.5 kg ha⁻¹ 28 Day

Collembola

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)

> 100

Apis mellifera

Low

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

> 101.7

Apis mellifera

Low

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

Chronic

Notes

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)

2.4% Mortality at dose 600 g ha⁻¹

Chrysoperla carnea Larva corr

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

90.2

Aphidius rhopalosiphi

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

137.6

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)

> 220

Oncorhynchus mykiss

Low

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

21.5

Oncorhynchus mykiss

Low

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

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

> 70.8

Daphnia magna

Moderate

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

62.5

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)

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

> 100

Lemna gibba

Low

Aquatic plants (rooted, growth) - Acute 14 day EC₅₀, biomass (mg l⁻¹)

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

> 74.9

Anabaena flos-aquae

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)

3940

Rat

Low

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 5.28

Rat 4 hr (nose only)

Other Mammal toxicity endpoints

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

0.07

Rat SF=100

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

2.0

Rat SF=100

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

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

0.1

Dog SF=100

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

Exposure Routes

Public

Negligible risk to bystanders

Occupational

PPE/PPC recommended

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

GB MRL amendment for carious crops, April 2025. Consult register.

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

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

No further information available

Handling issues

Property

Value and interpretation

General

Not expected to auto-ignite; Flammable
Not explosive or oxidising

CLP classification 2013

Health: H361d

WHO Classification

III (Slightly hazardous)

UN Number

Not regulated

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

Stable under ambient conditions

TRANSLATIONS

Language

Name

English

cycloxydim

French

cycloxydime

German

Cycloxydim

Danish

cycloxydim

Italian

cicloxidim

Spanish

cicloxidim

Greek

Polish

cykloksydym

Swedish

cykloxidim

Hungarian

cikloxidim

Dutch

cycloxydim

Norwegian

sykloksydim

Record last updated:	23/05/2025
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