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Chloroxuron (Ref: C 1983)
Last updated: 30/04/2021
(Also known as: chloroxyphenidin; chloroxyfenidim )

SUMMARY
Chloroxuron is a herbicide that is no longer approved for use in the UK or the EU. It has a low aqueous solubility and is not volatile. It is moderately persistent in soil systems but is unlikely to persist in aquatic systems. Based on its physico-chemical properties it is not expected to leach to groundwater. It is moderately toxic to birds, fish, aquatic invertebrates, algae and honey bees. Mammalian toxicity is low.
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:
Moderately persistent; Drainflow: Slightly mobile; Potential for particle bound transport: Medium
Ecotoxicity
Moderate alert:
Birds acute ecotoxicity: Moderate; Fish acute ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate; Bees acute contact ecotoxicity: Moderate
Human health
Moderate alert:
Possible Carcinogen
GENERAL INFORMATION
Description
An obsolete selective phenylurea herbicide once used to control annual grasses, mosses and broad-leaved weeds
Example pests controlled
Barnyardgrass; Nightshade; Carpetweed; Corn cockle; Dandelion; Goosegrass; Crabgrass; Ragweed; Puslane; Shepherd's purse; Pigweed; Velvetleaf
Example applications
Soybeans; Onions; Strawberries; Celery; Ornamentals; vegetables including onions, carrots, leeks, peas & beans
Efficacy & activity
-
Availability status
Obsolete
Introduction & key dates
1961, first reported
UK regulatory status
UK COPR regulatory status
Not approved
Date COPR inclusion expires
Expired
UK LERAP status
No UK approval for use
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)
Not applicable
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
Also used in
-
Chemical structure
Isomerism
-
Chemical formula
C₁₅H₁₅ClN₂O₂
Canonical SMILES
CN(C)C(=O)NC1=CC=C(C=C1)OC2=CC=C(C=C2)Cl
Isomeric SMILES
No data
International Chemical Identifier key (InChIKey)
IVUXTESCPZUGJC-UHFFFAOYSA-N
International Chemical Identifier (InChI)
InChI=1S/C15H15ClN2O2/c1-18(2)15(19)17-12-5-9-14(10-6-12)20-13-7-3-11(16)4-8-13/h3-10H,1-2H3,(H,17,19)
2D structure diagram/image available?
Yes
General status
Pesticide type
Herbicide
Substance group
Dimethylurea
Minimum active substance purity
-
Known relevant impurities
-
Substance origin
Synthetic
Mode of action
Photosynthetic electron transport inhibitor at the photosystem II receptor. Growth inhibition and chlorotic and necrotic effects on foliage
CAS RN
1982-47-4
EC number
217-843-7
CIPAC number
187
US EPA chemical code
025501
PubChem CID
16115
Molecular mass
290.75
PIN (Preferred Identification Name)
N'-[4-(4-chlorophenoxy)phenyl]-N,N-dimethylurea
IUPAC name
3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea
CAS name
N'-[4-(4-chlorophenoxy)phenyl]-N,N-dimethylurea
Other status information
-
Relevant Environmental Water Quality Standards
-
Herbicide Resistance Classification (HRAC)
C2
Herbicide Resistance Classification (WSSA)
7
Insecticide Resistance Classification (IRAC)
Not applicable
Fungicide Resistance Classification (FRAC)
Not applicable
Examples of recorded resistance
-
Physical state
Solid
Formulations
Property
Value
Example manufacturers & suppliers of products using this active now or historically
  • Tenoran
  • Norex
  • Gesamoos
Example products using this active
  • Syngenta
  • Ciba Geigy AG
Formulation and application details
Usually supplied as a wettable powder
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
3.7
K4 K = Research datasets, e.g. Pandora, Demetra
4 = Verified data
Low
Solubility - In organic solvents at 20 °C (mg l⁻¹)
44000
CA3 CA = Medical and toxicological databases and information systems e.g. TOXNET (click here )
3 = Unverified data of known source
Acetone
-
106000
CA3 CA = Medical and toxicological databases and information systems e.g. TOXNET (click here )
3 = Unverified data of known source
Dichloromethane
-
4000
CA3 CA = Medical and toxicological databases and information systems e.g. TOXNET (click here )
3 = Unverified data of known source
Toluene
-
35000
CA3 CA = Medical and toxicological databases and information systems e.g. TOXNET (click here )
3 = Unverified data of known source
Toluene
-
Melting point (°C)
151
Q3 Q = Miscellaneous internet resources
3 = Unverified data of known source
-
Boiling point (°C)
- - -
Degradation point (°C)
- - -
Flashpoint (°C)
- - -
Octanol-water partition coefficient at pH 7, 20 °C
P
2.51 X 1003 Calculated -
Log P
3.4
K4 K = Research datasets, e.g. Pandora, Demetra
4 = Verified data
High
Bulk density (g ml⁻¹)
- - -
Dissociation constant pKa) at 25 °C
- - -
-
Vapour pressure at 20 °C (mPa)
2.30 X 10-04
K4 K = Research datasets, e.g. Pandora, Demetra
4 = Verified data
Low volatility
Henry's law constant at 25 °C (Pa m³ mol⁻¹)
6.00 X 10-05
H4 H = The US ARS pesticide properties database (click here )
4 = Verified data
Non-volatile
Maximum UV-vis absorption L mol⁻¹ cm⁻¹
- - -
Surface tension (mN m⁻¹)
- - -
Degradation
Property
Value
Source; quality score; and other information
Interpretation
General biodegradability
-
Soil degradation (days) (aerobic)
DT₅₀ (typical)
36
K4 K = Research datasets, e.g. Pandora, Demetra
4 = Verified data
Moderately persistent
DT₅₀ (lab at 20 °C)
- - -
DT₅₀ (field)
60
F3 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents (US EPA Databases Related to Pesticide Risk Assessment )
3 = Unverified data of known source
Moderately persistent
DT₉₀ (lab at 20 °C)
- - -
DT₉₀ (field)
- - -
DT₅₀ modelling endpoint
- - -
Note
Literature states DT₅₀ typically ranges from 30 to 60 days, 110 days silt loam aerobic conditions (CA3)
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
0.015
K4 K = Research datasets, e.g. Pandora, Demetra
4 = Verified data
Fast
Note
-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7
Value
2896
K4 K = Research datasets, e.g. Pandora, Demetra
4 = Verified data
Very persistent
Note
-
Water-sediment DT₅₀ (days)
- - -
Water phase only DT₅₀ (days)
63
K4 K = Research datasets, e.g. Pandora, Demetra
4 = Verified data
Stable
Soil adsorption and mobility
Property
Value
Source; quality score; and other information
Interpretation
Linear
Kd
-
H3 H = The US ARS pesticide properties database (click here )
3 = Unverified data of known source
Slightly mobile
Koc
2820
Notes and range
Best available data
Freundlich
Kf
- - -
Kfoc
-
1/n
-
Notes and range
-
pH sensitivity
-
Fate indices
Property
Value
Source; quality score; and other information
Interpretation
GUS leaching potential index
0.98 Calculated Low leachability
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate
Value
1.96 X 10-02 Calculated -
Note
-
Potential for particle bound transport index
Medium Calculated -
Potential for loss via drain flow
Slightly mobile Calculated -
Key metabolites
Metabolite
Formation medium
Estimated maximum occurrence fraction
1107/2009 relevancy
N-(4-chlorophenoxy)-phenyl-N-methylurea
Soil - Not assessed under 91/414 or 1107/2009
N-(4-chlorophenoxy)-phenylurea
Soil - Not assessed under 91/414 or 1107/2009
4-chlorophenoxy-aniline
Soil - Not assessed under 91/414 or 1107/2009
ECOTOXICOLOGY
Property
Value
Source; quality score; and other information
Interpretation
Bio-concentration factor
BCF (l kg⁻¹)
105
Q2 Q = Miscellaneous internet resources
2 = Unverified data of unknown source
Estimated
Threshold for concern
CT₅₀ (days)
Not available -
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
> 3700
V3 V = ChemID online databases / IPCS INCHEM (ChemID; IPCS INCHEM )
3 = Unverified data of known source
Rat
Low
Mammals - Short term dietary NOEL
(mg kg⁻¹)
- - -
(ppm diet)
- -
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)
- - -
Birds - Acute LD₅₀ (mg kg⁻¹)
2000
F3 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents (US EPA Databases Related to Pesticide Risk Assessment )
3 = Unverified data of known source
Anas platyrhynchos
Moderate
Birds - Short term dietary (LC₅₀/LD₅₀)
- - -
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)
- - -
Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
100
F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents (US EPA Databases Related to Pesticide Risk Assessment )
4 = Verified data
Oncorhynchus mykiss
Moderate
Fish - Chronic 21 day NOEC (mg l⁻¹)
- - -
Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)
2.95
F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents (US EPA Databases Related to Pesticide Risk Assessment )
4 = Verified data
Daphnia magna
Moderate
Aquatic invertebrates - Chronic 21 day NOEC (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 - Acute 7 day EC₅₀, biomass (mg l⁻¹)
- - -
Non-target plants
- - -
- - -
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)
0.016
K3 K = Research datasets, e.g. Pandora, Demetra
3 = Unverified data of known source
Unknown species
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)
16
K4 K = Research datasets, e.g. Pandora, Demetra
4 = Verified data
Moderate
Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
- - -
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)
- - -
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
- - -
Other arthropod (2)
LR₅₀ g ha⁻¹
- - -
% Effect
- - -
Soil micro-organisms
- - -
Mesocosm study data
NOEAEC mg l⁻¹
- - -
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)
> 3700
V3 V = ChemID online databases / IPCS INCHEM (ChemID; IPCS INCHEM )
3 = Unverified data of known source
Rat
Low
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
- - -
Mammals - Inhalation LC₅₀ (mg l⁻¹)
- - -
Other Mammal toxicity endpoints
- - -
ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)
- - -
ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)
- - -
AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)
- - -
AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)
- - -
Dermal penetration studies (%)
- - -
Dangerous Substances Directive 76/464
- - -
Exposure Routes
Public
-
Occupational
Occupational exposure may occur through inhalation of dusts and dermal contact
MRLs
European
EU MRL pesticide database 
Notes
-
Drinking Water Standards
- - -
Drinking Water MAC (μg l⁻¹)
- - -
Health issues
Specific human health issues
Carcinogen
Genotoxic
Endocrine disruptor
?Possibly, status not identified
A0 A = Chromosome aberration (EFSA database)
0 = No data
;
B0 B = DNA damage/repair (EFSA database)
0 = No data
;
C0 C = Gene mutation (EFSA database)
0 = No data
;
D0 D = Genome mutation (EFSA database)
0 = No data
;
E0 E = Unspecified genotoxicity type (miscellaneous data source)
0 = No data
XNo, known not to cause a problem
Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant
No data found
XNo, known not to cause a problem
XNo, known not to cause a problem
Respiratory tract irritant Skin irritant Skin sensitiser
?Possibly, status not identified
?Possibly, status not identified
No data found
Eye irritant Phototoxicant  
?Possibly, status not identified
No data found  
General human health issues
Harmful by ingestion and inhalation
May be harmful by skin contact
Under certain conditions may form carcinogenic dimethylnitrosamine
Handling issues
Property
Value and interpretation
General
Fire may produce irritating or poisonous gases
CLP classification 2013
Health: H332
Environment: H400
EC Risk Classification
Xn - Harmful: R20, R22
EC Safety Classification
-
WHO Classification
U (Unlikely to present an acute hazard)
UN Number
-
Waste disposal & packaging
-
TRANSLATIONS
Language
Name
English
chloroxuron
French
chloroxuron
German
Chloroxuron
Danish
chloroxuron
Italian
cloroxuron
Spanish
cloroxuron
Greek
-
Polish
chloroksuron
Swedish
-
Hungarian
-
Dutch
chloroxuron

Record last updated: 30/04/2021
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