Clomazone (Ref: FMC 57020)

Clomazone (Ref: FMC 57020)	Last updated: 29/08/2024
(Also known as: dimethazone; fenoxan )

SUMMARY

Clomazone is a herbicide used to control broad-leaved weeds and grasses in a variety of crops. It is highly soluble in water and quite volatile so may be prone to drift. It is not persistent in soil system but may be persistent under certain conditions in waterbodies. It tends to be moderately toxic to most fauna and flora. It is moderately toxic to mammals and is considered to be a reproduction/developmental toxin.

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 Moderate alert: GUS: Transition state; Drainflow: Moderately mobile	Ecotoxicity Moderate alert: Birds chronic ecotoxicity: Moderate; Fish acute ecotoxicity: Moderate; Fish chronic ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate; Daphnia chronic ecotoxicity: Moderate; Bees acute contact ecotoxicity: Moderate; Bees acute oral ecotoxicity: Moderate; Earthworms acute ecotoxicity: Moderate; Earthworms chronic ecotoxicity: Moderate	Human health High alert: Reproduction/development effects

GENERAL INFORMATION

Description

Used for the control of broad-leaved weeds and grasses in a range of crops

Example pests controlled

Nightshade; Pigweed; Potato weed; Fathen; Hogweed; Wild radish; Staggerweed

Example applications

Cotton; Vegetables including peas, potatoes, sweet potatoes, green beans, navy beans; Curcubits; Tobacco; Rice; Oilseed rape

Efficacy & activity

Efficiacy demonstrated through field trials and extensive use.

Availability status

Current

Introduction & key dates

circa 1985, introduced

UK regulatory status

UK COPR regulatory status

Approved

Date COPR inclusion expires

15/06/2025

UK LERAP status

Check label - may vary with formulation

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

Denmark/Germany

Date EC 1107/2009 inclusion expires

15/06/2025

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

Australia, USA, Morocco

Chemical structure

Isomerism

None

Chemical formula

C₁₂H₁₄ClNO₂

Canonical SMILES

CC1(CON(C1=O)CC2=CC=CC=C2Cl)C

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

KIEDNEWSYUYDSN-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C12H14ClNO2/c1-12(2)8-16-14(11(12)15)7-9-5-3-4-6-10(9)13/h3-6H,7-8H2,1-2H3

2D structure diagram/image available?

Yes

General status

Pesticide type

Herbicide

Substance groups

Isoxazolidinone herbicide

Minimum active substance purity

960 g kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

Causes disruption of chlorophyll and carotenes synthesis causing chlorosis of the target plants and death due to energy depletion.

CAS RN

81777-89-1

EC number

617-258-0

CIPAC number

509

US EPA chemical code

125401

PubChem CID

54778

CLP index number

No data found

Molecular mass

239.7

PIN (Preferred Identification Name)

2-[(2-chlorophenyl)methyl]-4,4-dimethyl-1,2-oxazolidin-3-one

IUPAC name

2-(2-chlorobenzyl)-4,4-dimethyl-1,2-oxazolidin-3-one

CAS name

2-[(2-chlorophenyl)methyl]-4,4-dimethyl-3-isoxazolidinone

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

Lolium rigidum

Physical state

Pale straw coloured liquid

Formulations

Property

Value

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

Belchim
Greencrop
FMC Corp
Agriguard

Example products using this active

Centium 36 CS
Command
Gamit
Clone

Formulation and application details

Often available as a capsule suspension that is mixed with water and used as a spray

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

1212

High

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

250000

Acetone

955000

Dichloromethane

161800

n-Heptane

969000

Methanol

Melting point (°C)

33.9

Boiling point (°C)

281.7

Degradation point (°C)

Flashpoint (°C)

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

3.80 X 10⁰²

Calculated

Log P

2.58

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.19

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

27.0

Highly volatile. If applied directly to plants or soil, drift is a concern & mitigation is advisable

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

5.9 X 10^-03

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 pH: 195.5nm=28437.1, 210nm=14539.4
Acid pH: 201.5nm=15338.4, 210nm=14406.2
Basic pH; 197.5=24091.1, 210nm=14551.5

Surface tension (mN m⁻¹)

45.98

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

22.6

Non-persistent

DT₅₀ (lab at 20 °C)

22.6

Non-persistent

DT₅₀ (field)

27.3

Non-persistent

DT₉₀ (lab at 20 °C)

135.3

Persistent

DT₉₀ (field)

262

DT₅₀ modelling endpoint

Note

EU 2018 dossier lab studies DT₅₀ (normalised) range 6.3-145.7 days,DT₉₀ range 32.3-617 days, Soils=28; field studies DT₅₀ (normalised) range: 9.3-195 days, DT₉₀ range 65.4-645 days,Soils=19

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

Stable

Note

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

Value

Stable

Note

Stable at pH 5 to pH 9, 25 °C

Water-sediment DT₅₀ (days)

Moderately fast

Water 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)

Moderately mobile

K_oc (mL g⁻¹)

300

Notes and range

Freundlich

K_f (mL g⁻¹)

2.08

Moderately mobile

K_foc (mL g⁻¹)

128.3

¹/_n

0.90

Notes and range

EU 2018 dossier K_f range 0.45-4.04 mL g⁻¹, K_foc range 33-317 mL g⁻¹, ¹/_n range 0.81-0.99, Soils=20

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

2.72

Calculated

Transition state

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

Value

1.79 X 10^-01

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Moderately mobile

Calculated

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

0.487

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)

Whole fish

Low potential

CT₅₀ (days)

Known soil metabolites

Metabolite

Major/Minor fraction

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

Estimated maximum occurrence fraction

Notes

(N-((2-chlorobenzyl))-3-hydroxy-2,2-dimethylpropanamide) (Ref: FMC 653167)

Major fraction

0.250

Known groundwater metabolites

Metabolite

EC SANCO/221/2000 relevancy

ADI (mg kg⁻¹ bodyweight day⁻¹)

WHO drinking water guidance value (μg L⁻¹ day⁻¹)

(N-((2-chlorobenzyl))-3-hydroxy-2,2-dimethylpropanamide) (Ref: FMC 653167)

Not relevant

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

hydroxy-2-chlorobenzyl alcohol

Plant

2-chlorobenzoic acid

Plant

2-chlorobenzyl alcohol (Ref: FMC 61569)

OCB-alcohol

Plant

N-[(2-chlorobenzyl)]-2-methyl propanamide (Ref: FMC 55657)

Water; Water/sediment

isoxazolidine (Ref: FMC 57091)

Plant

2-[(2-chlorophenyl)methyl]-4,4-dimethyl-1,2-oxazolidine-3,5-dione

5-keto-clomazone

Plant

5-hydroxyclomazone

Plant

hydroymethyl clomazone

Plant

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

754

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

13.3

Rat

High

(ppm diet)

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

314

Rat Reproductive NOAEL

Low

Birds - Acute LD₅₀ (mg kg⁻¹)

> 2224

Colinus virginianus

Low

Birds - Short term dietary (LC₅₀/LD₅₀)

> 5620 ppm

Colinus virginianus

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

76.5

Colinus virginianus NOEC

Moderate

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

Eisenia foetida corr

Moderate

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

> 0.8

Eisenia foetida

Moderate

Soil micro-organisms

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

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

11.3

Folsomia candida

Non-target plants

Honeybees (Apis spp.)

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

> 89.5

Apis mellifera

Moderate

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

> 76.33

Apis mellifera

Moderate

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

Chronic as 10-day LDD₅₀ µg bee⁻¹ day⁻¹

14.12

Apis mellifera

Bumblebees (Bombus spp.)

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

> 968

Bombus terrestris

Low

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

> 968

Bombus terrestris

Low

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

> 360

Aphidius rhopalosiphi

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

> 360

Typhlodromus pyri

Beneficial insects (Ground beetles) as Mortality LR₅₀ g ha⁻¹

> 360

Poecilus cupreus

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

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

14.4

Oncorhynchus mykiss

Moderate

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

2.30

Oncorhynchus mykiss

Moderate

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

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

12.7

Daphnia magna

Moderate

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

2.2

Daphnia magna

Moderate

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

Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)

0.53

Americamysis bahia

Moderate

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)

60.5

Chironomus riparius

Moderate

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

34.0

Lemna gibba

Low

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

0.136

Navicula pelliculosa 120 hr

Moderate

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

0.05

Navicula pelliculosa 120 hr

Moderate

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)

754

Rat

Moderate

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

4.3

Rat 4 hr (whole body)

Other Mammal toxicity endpoints

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

0.133

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

None allocated

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

2.5

Rat SF=100

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

0.133

Dermal penetration studies (%)

25-75

concentration dependent

Dangerous Substances Directive 76/464

Exposure Routes

Public

Minor risk to residents and bystanders considering expected patterns of use

Occupational

PPE/PPC advised

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

Mammalian dose elimination route and rate

Excretion normally within 2 days, 70% urine, 30% faeces

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

Moderately toxic
Possible liver toxicant

Handling issues

Property

Value and interpretation

General

Not explosive or oxidising
IMDG Transport Hazard Class 9
Not expected to auto-ignite; Not highly flammable

CLP classification 2013

Health: H302, H312, H315, H319, H332
Environment: H400, H410, H411, H412

WHO Classification

II (Moderately hazardous)

UN Number

UN3082

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

Chemically stable under standard ambient conditions

TRANSLATIONS

Language

Name

English

clomazone

French

clomazone

German

Clomazone

Danish

clomazone

Italian

clomazone

Spanish

clomazona

Greek

Polish

chlomazon

Swedish

klomazon

Hungarian

klomazon

Dutch

clomazone

Norwegian

klomazon

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