Defenuron is an obsolete herbicide. It is highly soluble in water and is non-volatile. It has a low toxicity to fish. It is not highly toxic to mammals if ingested.
Hazard 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. These hazard alerts do not take account of usage patterns or exposure, thus do not represent risk.
Environmental fate
Ecotoxicity
Human health
Human health Moderate alert: Genotoxic
Warning: Significant data are missing
GENERAL INFORMATION
Description
An obsolete herbicide that was used to control weeds in a range of crops
Photosyntheis inhibition, active via leaves and roots
CAS RN
1007-36-9
EC number
No data found
CIPAC number
None allocated
US EPA chemical code
-
PubChem CID
13880
CLP index number
No data found
Molecular mass
150.18
PIN (Preferred Identification Name)
1-methyl-3-phenylurea
IUPAC name
1-methyl-3-phenylurea
CAS name
N-phenyl-N-methylurea
Forever chemical
-
Other status information
-
Relevant Environmental Water Quality Standards
-
Herbicide Resistance Class (HRAC MoA class)
Not known
Herbicide Resistance Class (WSSA MoA class)
Not known
Insecticide Resistance Class (IRAC MoA class)
Not applicable
Fungicide Resistance Class (FRAC MOA class)
Not applicable
Examples of recorded resistance
-
Physical state
Colourless crystalline solid
Commercial
Property
Value
Availability status
Considered obsolete but may be available in some countries
Introduction & key dates
Early 1970s, first synthesised; 1970s-1980s, limited agriclutural use; 1990s, declining use; 2000s, considered obsolete
Example manufacturers & suppliers of products using this active now or historically
-
Example products using this active
Obsolete - not thought to be commercially available for crop protection applications
Formulation and application details
Was usually supplied as a wettable powder
Commercial production
-
Impact on climate of production and use
-
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
1270
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
High
Solubility - In organic solvents at 20 °C (mg l⁻¹)
7200
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Ethanol
-
1000
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Benzene
-
3310
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Methylene chloride
-
Melting point (°C)
148
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
-
Boiling point (°C)
232
Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source
-
Degradation point (°C)
-
-
-
Flashpoint (°C)
98.9
Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source
-
Octanol-water partition coefficient at pH 7, 20 °C
P
1.32 X 1001
Calculated
-
Log P
1.12
V2 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 2 = Unverified data of unknown source
Low
Fat solubility of residues
Solubility
-
-
-
Data type
-
-
-
Density (g ml⁻¹)
1.143
Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source
-
Dissociation constant pKa) at 25 °C
-
-
-
-
Vapour pressure at 20 °C (mPa)
1.0 X 10-02
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Low volatility
Henry's law constant at 25 °C (Pa m³ mol⁻¹)
1.8 X 10-06
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
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)
-
-
-
Degradation
Property
Value
Source; quality score; and other information
Interpretation
General biodegradability
-
Soil degradation (days) (aerobic)
DT₅₀ (typical)
-
-
-
DT₅₀ (lab at 20 °C)
-
-
-
DT₅₀ (field)
-
-
-
DT₉₀ (lab at 20 °C)
-
-
-
DT₉₀ (field)
-
-
-
DT₅₀ modelling endpoint
-
-
-
Note
-
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
-
-
-
Note
-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7
Value
-
-
-
Note
-
Water-sediment DT₅₀ (days)
-
-
-
Water phase only DT₅₀ (days)
-
-
-
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
Kd (mL g⁻¹)
-
-
-
Koc (mL g⁻¹)
-
Notes and range
-
Freundlich
Kf (mL g⁻¹)
-
-
-
Kfoc (mL g⁻¹)
-
1/n
-
Notes and range
-
pH sensitivity
-
Fate indices
Property
Value
Source; quality score; and other information
Interpretation
GUS leaching potential index
-
-
-
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate
Value
Cannot be calculated
-
-
Note
-
Potential for particle bound transport index
-
-
-
Potential for loss via drain flow
-
-
-
Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk
-
-
-
Bio-concentration factor
BCF (l kg⁻¹)
-
-
-
CT₅₀ (days)
-
-
Known metabolites
None
ECOTOXICOLOGY
Terrestrial ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
3440
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
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
Human health
Warning:
