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Fomesafen (Ref: PP 021)
Last updated: 15/09/2021
(Also known as: fomesafene; fomesafen acid)

SUMMARY
Fomesafen is a selective herbicide. It is moderately soluble in aqueous solution, is relatively volatile but does have potential to leach to groundwater. It is persistent in soils and aquatic systems. It is moderately toxic to mammals and although a recognised irritant no other significant health issues have been identified. It is not toxic to birds or fish but considered moderately toxic to aquatic crustaceans, honeybees and earthworms.
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; Drainflow: Mobile
Ecotoxicity
Moderate alert:
Bees acute oral ecotoxicity: Moderate; Earthworms acute ecotoxicity: Moderate
Human health
Moderate alert:
Mammals acute toxicity: Moderate; Possible Reproduction/development effects
GENERAL INFORMATION
Description
A pre-emergence herbicide for use in leguminous crops for post-emergence control of broad-leaved weeds
Example pests controlled
Pigweed, Black nightshade, Velvetleaf, Cocklebur
Example applications
Legumes; Cotton; Soybeans; Potatoes; Tomatoes
Efficacy & activity
-
Availability status
Unknown
Introduction & key dates
1983, 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
-
Date EC 1107/2009 inclusion expires
Expired
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
                 
Additional information
Also used in
-
Chemical structure
Isomerism
None
Chemical formula
C₁₅H₁₀ClF₃N₂O₆S
Canonical SMILES
CS(=O)(=O)NC(=O)C1=C(C=CC(=C1)OC2=C(C=C(C=C2)C(F)(F)F)Cl)[N+](=O)[O-]
Isomeric SMILES
No data
International Chemical Identifier key (InChIKey)
BGZZWXTVIYUUEY-UHFFFAOYSA-N
International Chemical Identifier (InChI)
InChI=1S/C15H10ClF3N2O6S/c1-28(25,26)20-14(22)10-7-9(3-4-12(10)21(23)24)27-13-5-2-8(6-11(13)16)15(17,18)19/h2-7H,1H3,(H,20,22)
2D structure diagram/image available?
Yes
General status
Pesticide type
Herbicide
Substance group
Organochlorine
Minimum active substance purity
-
Known relevant impurities
-
Substance origin
Synthetic
Mode of action
Selective, absorbed by leaves and roots. Inhibits protoporphyrinogen oxidase (PROTOX), leading to irreversible cell membrane damage.
CAS RN
72178-02-0
EC number
276-439-9
CIPAC number
8162
US EPA chemical code
123802
PubChem CID
51556
Molecular mass
438.76
PIN (Preferred Identification Name)
-
IUPAC name
5-(2-chloro-α,α,α-trifluoro-p-tolyloxy)-N-mesyl-2-nitrobenzamide
CAS name
5-[2-chloro-4-(trifluoromethyl)phenoxy]-N-(methylsulfonyl)-2-nitrobenzamide
Other status information
-
Relevant Environmental Water Quality Standards
-
Herbicide Resistance Classification (HRAC)
E
Herbicide Resistance Classification (WSSA)
14
Insecticide Resistance Classification (IRAC)
Not applicable
Fungicide Resistance Classification (FRAC)
Not applicable
Examples of recorded resistance
Amaranthus rudis, Euphorbia heterophylla
Physical state
White crystals
Related substances & organisms
Formulations
Property
Value
Example manufacturers & suppliers of products using this active now or historically
  • FCC Ltd
  • King Tech
  • AgroCare
  • ICI Plant Protection
Example products using this active
  • Eagrow
  • Reflex
  • Flexstar
  • Format
Formulation and application details
Usually supplied as an soluble concentrate or liquid concentratate.
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
50
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
Moderate
Solubility - In organic solvents at 20 °C (mg l⁻¹)
300000
C4 C = AGRITOX (click here )
4 = Verified data
Acetone
-
25000
C4 C = AGRITOX (click here )
4 = Verified data
Methanol
-
1900
C4 C = AGRITOX (click here )
4 = Verified data
Xylene
-
10000
C4 C = AGRITOX (click here )
4 = Verified data
Dichloromethane
-
Melting point (°C)
219
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
-
Boiling point (°C)
- - -
Degradation point (°C)
- - -
Flashpoint (°C)
- - -
Octanol-water partition coefficient at pH 7, 20 °C
P
6.31 X 10-02 Calculated -
Log P
-1.2
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
Low
Bulk density (g ml⁻¹)
1.61
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
-
Dissociation constant pKa) at 25 °C
2.83
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
-
Forms water soluble salts, strong acid
Vapour pressure at 20 °C (mPa)
4.00 X 10-03
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)
2.00 X 10-07
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
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)
86
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
Moderately persistent
DT₅₀ (lab at 20 °C)
- - -
DT₅₀ (field)
86
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
Moderately persistent
DT₉₀ (lab at 20 °C)
- - -
DT₉₀ (field)
- - -
DT₅₀ modelling endpoint
- - -
Note
Field studies DT₅₀ range 59-112 days
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
Stable
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Stable
Note
-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7
Value
- - -
Note
-
Water-sediment DT₅₀ (days)
7
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
Fast
Water phase only DT₅₀ (days)
- - -
Soil adsorption and mobility
Property
Value
Source; quality score; and other information
Interpretation
Linear
Kd
-
B4 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
4 = Verified data
Mobile
Koc
50
Notes and range
Literature studies state Koc range 150-1200 (R3)
Freundlich
Kf
1.89
R4 R = Peer reviewed scientific publications
4 = Verified data
Moderately mobile
Kfoc
228
1/n
0.77
Notes and range
Literature data: Kf range 1.38-3.02 mL g⁻¹, Kfoc range 115-348 mL g⁻¹, 1/n range 0.65-0.83, soils=6
pH sensitivity
R4
Fate indices
Property
Value
Source; quality score; and other information
Interpretation
GUS leaching potential index
3.18 Calculated High leachability
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate
Value
4.08 X 10-01 Calculated -
Note
-
Potential for particle bound transport index
Medium Calculated -
Potential for loss via drain flow
Mobile Calculated -
ECOTOXICOLOGY
Property
Value
Source; quality score; and other information
Interpretation
Bio-concentration factor
BCF (l kg⁻¹)
6
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
Whole fish
Low potential
CT₅₀ (days)
Not available -
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
1250
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
Rat
Moderate
Mammals - Short term dietary NOEL
(mg kg⁻¹)
0.25
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
Rat
High
(ppm diet)
5 -
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)
- - -
Birds - Acute LD₅₀ (mg kg⁻¹)
> 5000
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
Anas platyrhynchos
Low
Birds - Short term dietary (LC₅₀/LD₅₀)
- - -
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)
- - -
Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
> 170
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
Oncorhynchus mykiss
Low
Fish - Chronic 21 day NOEC (mg l⁻¹)
- - -
Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)
> 330
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
Daphnia magna
Low
Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)
> 100
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
Daphnia magna LOEC
Low
Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)
22.1
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
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)
- - -
Aquatic plants - Acute 7 day EC₅₀, biomass (mg l⁻¹)
- - -
Non-target plants
- - -
- - -
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)
0.17
L2 L = Pesticide manuals and hard copy reference books / other sources
2 = Unverified data of unknown 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)
- - -
Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
50
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
Moderate
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)
1000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Moderate
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)
1250
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
Rat
Moderate
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
1000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rabbit
-
Mammals - Inhalation LC₅₀ (mg l⁻¹)
> 4.97
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)
0.003
B4 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
4 = Verified data
UK ACP 1999
-
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
List I - -
Exposure Routes
Public
-
Occupational
Occupational exposure may occur through inhalation of spray mists and aerosols and dermal contact
MRLs
European
EU MRL pesticide database 
Great Britain
GB MRL Register 
Notes
-
Drinking Water Standards
- - -
Drinking Water MAC (μg l⁻¹)
- - -
Health issues
Specific human health issues
Carcinogen
Genotoxic
Endocrine disruptor
XNo, known not to cause a problem
A3 A = Chromosome aberration (EFSA database)
3 = Negative
;
B3 B = DNA damage/repair (EFSA database)
3 = Negative
;
C3 C = Gene mutation (EFSA database)
3 = Negative
;
D0 D = Genome mutation (EFSA database)
0 = No data
;
E0 E = Unspecified genotoxicity type (miscellaneous data source)
0 = No data
No data found
Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant
?Possibly, status not identified
XNo, known not to cause a problem
XNo, known not to cause a problem
Respiratory tract irritant Skin irritant Skin sensitiser
Yes, known to cause a problem
Yes, known to cause a problem
?Possibly, status not identified
Eye irritant Phototoxicant  
Yes, known to cause a problem
No data found  
General human health issues
Probably liver toxicant
Handling issues
Property
Value and interpretation
General
No information available
CLP classification 2013
Health: H302
EC Risk Classification
Xn - Harmful: R22
EC Safety Classification
S2
WHO Classification
II (Moderately hazardous)
UN Number
-
Waste disposal & packaging
-
TRANSLATIONS
Language
Name
English
fomesafen
French
fomesafen
German
Fomesafen
Danish
fomesafen
Italian
fomosafen
Spanish
fomesafen
Greek
-
Polish
fomesafen
Swedish
-
Hungarian
fomezafen
Dutch
-

Record last updated: 15/09/2021
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