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Fentrazamide (Ref: BAY YRC 2388)
Last updated: 24/07/2024
(Also known as: YRC 2388; NBA 061)

SUMMARY
Fentrazamide is a tetrazolinone herbicide for use in rice. It has a very low aqueous solubility, is relatively volatile and very persistent in water systems but much less so in soil. It has a low mammalian toxicity, however there is little reported information on human health effects. It is moderately toxic to birds, most aquatic organisms and earthworms but is not toxic to honeybees.
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:
GUS: High leachability
Warning:
Significant data are missing
Ecotoxicity
Moderate alert:
Fish acute ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate
Human health
Low alert
Warning:
Significant data are missing
GENERAL INFORMATION
Description
A post-emergence herbicide for rice crops
Example pests controlled
Barnyard grass, Annual sedges, Broadleaved weeds
Example applications
Rice
Efficacy & activity
-
Availability status
Current
Introduction & key dates
circa 1997, introduced
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
Not approved
Dossier rapporteur/co-rapporteur
Not applicable
Date EC 1107/2009 inclusion expires
Not applicable
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
                 
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
Japan, Korea
Chemical structure
Isomerism
None
Chemical formula
C₁₆H₂₀ClN₅O₂
Canonical SMILES
CCN(C1CCCCC1)C(=O)N2C(=O)N(N=N2)C3=CC=CC=C3Cl
Isomeric SMILES
-
International Chemical Identifier key (InChIKey)
LLQPHQFNMLZJMP-UHFFFAOYSA-N
International Chemical Identifier (InChI)
InChI=1S/C16H20ClN5O2/c1-2-20(12-8-4-3-5-9-12)15(23)22-16(24)21(18-19-22)14-11-7-6-10-13(14)17/h6-7,10-12H,2-5,8-9H2,1H3
2D structure diagram/image available?
Yes
General status
Pesticide type
Herbicide
Substance groups
Tetrazolinone herbicide
Minimum active substance purity
-
Known relevant impurities
-
Substance origin
Synthetic
Mode of action
Selective. Inhibition of very long chain fatty acids (VLCFA, inhibition of cell division)
CAS RN
158237-07-1
EC number
605-140-1
CIPAC number
None allocated
US EPA chemical code
-
PubChem CID
3081363
CLP index number
No data found
Molecular mass
349.82
PIN (Preferred Identification Name)
4-(2-chlorophenyl)-N-cyclohexyl-N-ethyl-5-oxo-4,5-dihydro-1H-tetrazole-1-carboxamide
IUPAC name
4-(2-chlorophenyl)-N-cyclohexyl-N-ethyl-4,5-dihydro-5-oxo-1H-tetrazole-1-carboxamide
CAS name
4-(2-chlorophenyl)-N-cyclohexyl-N-ethyl-4,5-dihydro-5-oxo-1H-tetrazole-1-carboxamide
Other status information
-
Relevant Environmental Water Quality Standards
-
Herbicide Resistance Class (HRAC MoA class)
K3
Herbicide Resistance Class (WSSA MoA class)
15
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
Formulations
Property
Value
Example manufacturers & suppliers of products using this active now or historically
  • Bayer CropScience
Example products using this active
  • Lecs
Formulation and application details
-
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
2.3
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID )
3 = Unverified data of known source
at 25 °C
Low
Solubility - In organic solvents at 20 °C (mg l⁻¹)
2100
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
n-Heptane
-
32000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Isopropanol
-
250000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Xylene
-
250000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Dichloromethane
-
Melting point (°C)
79
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID )
3 = Unverified data of known source
-
Boiling point (°C)
- - -
Degradation point (°C)
- - -
Flashpoint (°C)
- - -
Octanol-water partition coefficient at pH 7, 20 °C
P
3.98 X 1003 Calculated -
Log P
3.60
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
High
Fat solubility of residues
Solubility
- - -
Data type
- - -
Density (g ml⁻¹)
1.30
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
-
Dissociation constant pKa) at 25 °C
- - -
-
Vapour pressure at 20 °C (mPa)
0.05
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)
7.0 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)
30
R3 R = Peer reviewed scientific publications
3 = Unverified data of known source
Moderately persistent
DT₅₀ (lab at 20 °C)
- - -
DT₅₀ (field)
- - -
DT₉₀ (lab at 20 °C)
- - -
DT₉₀ (field)
- - -
DT₅₀ modelling endpoint
- - -
Note
Literature values state DT₅₀ in paddy field conditions is around 30 days in volcanic soil and 20 days in alluvial soil.
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
20
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Slow
Note
DT₅₀ 20 days in pure water, 10 days in natural waters
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7
Value
Stable
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Stable
Note
Stable pH 5 to pH 9
Water-sediment DT₅₀ (days)
- - -
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
Kd (mL g⁻¹)
-
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
Moderately mobile
Koc (mL g⁻¹)
100
Notes and range
Literature values range from 300 to 3400
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
2.95 Calculated High leachability
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate
Value
2.49 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
- - -
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)
> 5000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rat
Low
Mammals - Short term dietary NOEL
(mg kg⁻¹)
10.3
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rat
High
(ppm diet)
- -
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)
- - -
Birds - Acute LD₅₀ (mg kg⁻¹)
> 2000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Coturnix japonica
Low
Birds - Short term dietary (LC₅₀/LD₅₀)
- - -
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)
- - -
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)
> 1000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Low
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)
- - -
Soil micro-organisms
- - -
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)
> 150
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Low
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)
- - -
Chronic
- - -
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)
- - -
Beneficial insects (Parasitic wasps)
- - -
Beneficial insects (Predatory mites)
- - -
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)
3.4
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Oncorhynchus mykiss
Moderate
Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)
- - -
Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
- - -
Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)
> 10.0
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Daphnia magna
Moderate
Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)
- - -
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 - Acute 7 day EC₅₀, biomass (mg l⁻¹)
- - -
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)
0.006
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Green algae
High
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)
- - -
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)
> 5000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rat
Low
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
5000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rat
-
Mammals - Inhalation LC₅₀ (mg l⁻¹)
> 5.0
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rat
-
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
-
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
- - -
Health issues
Specific human health issues
Carcinogen
Genotoxic
Endocrine disruptor
No data found
A3 A = Chromosome aberration (EFSA database)
3 = Negative
;
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
;
E3 E = Unspecified genotoxicity type (miscellaneous data source)
3 = Negative
No data found
Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant
No data found
XNo, known not to cause a problem
No data found
Respiratory tract irritant Skin irritant Skin sensitiser
No data found
XNo, known not to cause a problem
No data found
Eye irritant Phototoxicant  
XNo, known not to cause a problem
No data found  
General human health issues
No further information available
Handling issues
Property
Value and interpretation
General
IMDG Transport Hazard Class 9
Not expected to auto-ignite; Not highly flammable
CLP classification 2013
Environment: H400
WHO Classification
Not listed (Not listed)
UN Number
UN3077
Waste disposal & packaging
Packaging Group III (minor danger)
Shelf-life, storage, stability and reactivity
-
TRANSLATIONS
Language
Name
English
fentrazamide
French
-
German
-
Danish
-
Italian
-
Spanish
-
Greek
-
Polish
fentrazamid
Swedish
-
Hungarian
-
Dutch
-
Norwegian
-

Record last updated: 24/07/2024
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