Fenamidone (Ref: RPA 407213)

Fenamidone (Ref: RPA 407213)	Last updated: 22/05/2025
(Not known by any other names)

SUMMARY

Fenamidone is an imidazole fungicide used to treat Oomycete diseases on a wide range of crops. It has a low aqueous solubility but is soluble in many organic solvents. It is not normally persistent in soil or water systems. Fenamidone is moderately toxic to most terrestrial and aquatic species. It has a low human oral toxicity and no chronic health implications have been identified.

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: 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 Moderate alert: Genotoxic; Reproduction/development effects

GENERAL INFORMATION

Description

A fungicide effective against Oomycete diseases such as downy mildew and certain leaf spot diseases

Example pests controlled

Early and Late blight; Downy mildew; Alternaria leaf spot; Purple blotch

Example applications

Bulb vegetable crops; Potatoes; Tomatoes; Lettuce; Curcubits

Efficacy & activity

Availability status

Current

Introduction & key dates

1998, first reported; 2001, first registered

GB regulatory status

GB COPR regulatory status

Not approved

Date COPR inclusion expires

Expired

GB LERAP status

No UK approval for use as a plant protection agent

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Not approved

Dossier rapporteur/co-rapporteur

Czech Republic/France

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
			✓	✓	✓

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

Chemical structure

Isomerism

A chiral molecule however only the S-isomer is biologically active and commercial products are stereospecific

Chemical formula

C₁₇H₁₇N₃OS

Canonical SMILES

CC1(C(=O)N(C(=N1)SC)NC2=CC=CC=C2)C3=CC=CC=C3

Isomeric SMILES

C[C@@]1(C(=O)N(C(=N1)SC)NC2=CC=CC=C2)C3=CC=CC=C3

International Chemical Identifier key (InChIKey)

LMVPQMGRYSRMIW-KRWDZBQOSA-N

International Chemical Identifier (InChI)

InChI=1S/C17H17N3OS/c1-17(13-9-5-3-6-10-13)15(21)20(16(18-17)22-2)19-14-11-7-4-8-12-14/h3-12,19H,1-2H3/t17-/m0/s1

2D structure diagram/image available?

Yes

General status

Pesticide type

Fungicide

Substance groups

Imidazole fungicide

Minimum active substance purity

975 g kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

Protective and curative action. Respiration inhibitor (QoL fungicide).

CAS RN

161326-34-7

EC number

605-252-0

CIPAC number

650

US EPA chemical code

046679

PubChem CID

10403199

CLP index number

613-206-00-6

Molecular mass

311.40

PIN (Preferred Identification Name)

(5S)-3-anilino-5-methyl-2-(methylsulfanyl)-5-phenyl-3,5-dihydro-4H-imidazol-4-one

IUPAC name

(S)-1-anilino-4-methyl-2-methylthio-4-phenylimidazolin-5-one

CAS name

(5S)-3,5-dihydro-5-methyl-2-(methylthio)-5-phenyl-3-(phenylamino)-4H-imidazol-4-one

Other status information

Relevant Environmental Water Quality Standards

Herbicide Resistance Class (HRAC MoA class)

Not applicable

Herbicide Resistance Class (WSSA MoA class)

Not applicable

Insecticide Resistance Class (IRAC MoA class)

Not applicable

Fungicide Resistance Class (FRAC MOA class)

Examples of recorded resistance

Physical state

White to cream fine powder

Formulations

Property

Value

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

Bayer CropScience

Example products using this active

Consento
Reason

Formulation and application details

Often available as a soluble concentrate that is diluted 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)

7.8

Low

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

250000

Acetone

105700

Ethyl acetate

300

n-Heptane

43100

Methanol

Melting point (°C)

136.8

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

240

Flashpoint (°C)

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

6.31 X 10⁰²

Calculated

Log P

2.8

Moderate

Fat solubility of residues

Solubility

Insoluble

Data type

Regulatory data based on logP - bioaccumulation in animal tissue unlikely

Density (g ml⁻¹)

1.29

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

0.00034

Low volatility

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

5.00 X 10^-06

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

Negligible

From soil surface

Negligible

Maximum UV-vis absorption L mol⁻¹ cm⁻¹

Neutral pH: 202.5nm = 18470, 230 nm = 9148
Acidic pH; 203nm = 25138, 230nm=15734
Alkaline pH: 228.5 = 38838

Surface tension (mN m⁻¹)

72.9

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

6.9

Non-persistent

DT₅₀ (lab at 20 °C)

6.9

Non-persistent

DT₅₀ (field)

8.1

Non-persistent

DT₉₀ (lab at 20 °C)

30.0

Moderately persistent

DT₉₀ (field)

28.6

DT₅₀ modelling endpoint

Note

EU dossier (2016) Lab studies DT₅₀ range 0.5-20.9 days, DT₉₀ range 5.0-81.8 days, Soils=7; Field studies DT₅₀ range 4.6-51.2 days, DT₉₀ range 15.1-51.2 days

Dissipation rate RL₅₀ (days) on plant matrix

Value

3.5

Note

Gherkin fruit, n=1

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

9.4

Note

Published literature RL₅₀ range 2.5-18 days, 5 field & undercover grown crops, various matrices, n=7

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Moderately fast

Note

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

Value

411

Very persistent

Note

pH sensitive: DT₅₀ 221 days at pH 5, 27.6 days at pH 9

Water-sediment DT₅₀ (days)

Moderately fast

Water phase only DT₅₀ (days)

Slow

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

K_d (mL g⁻¹)

K_oc (mL g⁻¹)

Notes and range

Freundlich

K_f (mL g⁻¹)

5.1

Moderately mobile

K_foc (mL g⁻¹)

388

¹/_n

0.77

Notes and range

EU dossier K_f range 2.43-6.89 mL g⁻¹, K_foc range 259-494 mL g⁻¹, ¹/_n range 0.69-0.83, Soils=4

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.28

Calculated

Low leachability

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

Value

1.35 X 10^-02

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

0.16

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)

Low risk

Based on LogP < 3

Low risk

CT₅₀ (days)

No data

Known soil metabolites

Metabolite

Major/Minor fraction

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

Estimated maximum occurrence fraction

Notes

(5S)-5-methyl-3-[(2-nitrophenyl)amino]-5-phenyl- 2,4-midazolidinedione (Ref: RPA 221701)

Major fraction

0.115

(5S)-5-methyl-2-(methylthio)-3-(4-nitrophenyl)amino-5-phenyl-3,5-dihydro-4H-imidazol-4-one (Ref: RPA 411639)

Major fraction

0.117

(S)-5-methyl-5-phenylimidazolidine-2,4-dione (Ref: RPA 412636)

Major fraction

0.350

(S)-5-methyl-2-methylthio-3-(2-nitrophenylamino)-5-phenyl-3,5-dihydroimidazol-4-one (Ref: RPA 413255)

Major fraction

0.131

(S)-5-methyl-2-methylthio-5-phenyl-3,5-dihydroimidazol-4-one (Ref: RPA 412708)

Major fraction

0.172

(5S,5S)-3,3'-(1,2-diphenylhydrazine-1,2-diyl)bis[5-methyl-2-(methylthio)-5-phenyl-3,5-dihydro-4H-imidazol-4-one (Ref: BCS-CV62706)

Minor fraction

0.082

(5S)-5-methyl-3-[(4-nitrophenyl)amino]-5-phenyl- 2,4-imidazolidinedione (Ref: RPA 221607)

Major fraction

0.126

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)

(S)-5-methyl-5-phenylimidazolidine-2,4-dione (Ref: RPA 412636)

Not relevant

0.0064

38.4

(S)-5-methyl-2-methylthio-5-phenyl-3,5-dihydroimidazol-4-one (Ref: RPA 412708)

Relevant

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Ref: RPA 410193

(a) Plant; (b) Water (Photolysis)

b=0.134

Ref: RPA 409344

Water (Hydrolysis)

0.322

Ref: RPA 408056

Water (Photolysis)

0.356

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

2028

Rat

Low

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat

High

(ppm diet)

500

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

328

Rat Reproductive NOAEL

Low

Birds - Acute LD₅₀ (mg kg⁻¹)

> 2000

Colinus virginianus

Low

Birds - Short term dietary (LC₅₀/LD₅₀)

> 5200 ppm

Colinus virginianus

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

133

Colinus virginianus NOEL

Moderate

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

> 25

Eisenia foetida

Moderate

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

0.315

Eisenia foetida corr

Moderate

Soil micro-organisms

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

Dose: 1.6 kg ha⁻¹

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

4.51

Folsomia candida

Non-target plants

Honeybees (Apis spp.)

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

> 25.7

Apis mellifera

Moderate

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

> 93.3

Apis mellifera

Moderate

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

Chronic as 10-day LC₅₀ µg bee⁻¹ day⁻¹

2.62

Apis mellifera

Notes

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)

0.74

Oncorhynchus mykiss

Moderate

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

0.31

Oncorhynchus mykiss

Moderate

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

0.71

Danio rerio EC₅₀ Embryo

Moderate

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

0.19

Daphnia magna

Moderate

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

0.0125

Daphnia magna

Moderate

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)

0.05

Chironomus riparius

Moderate

Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg⁻¹)

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

0.88

Lemna gibba

Moderate

Aquatic plants (rooted, growth) - Acute 14 day EC₅₀, biomass (mg l⁻¹)

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

3.84

Raphidocelis subcapitata

Moderate

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

Mesocosm study data

NOEAEC mg l⁻¹

Marine bivalves

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)

2028

Rat

Low

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 2.1

Rat 4 hr (nose only)

Other Mammal toxicity endpoints

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

None allocated

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

None allocated

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

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

None allocated

Dermal penetration studies (%)

1.75-4.3

concentration dependent

Dangerous Substances Directive 76/464

Exposure Routes

Public

Minimal risk of dietary exposure

Occupational

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

New GB MRL in place from 24 April 2023

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

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

General human health issues

Possible liver and thyroid toxicant

Handling issues

Property

Value and interpretation

General

Prevent generation of mists
Not explosive or oxidising
IMDG Transport Hazard Class 9
Not explected to auto-ignite, Not highly flammable

CLP classification 2013

Environment: H400, H410

WHO Classification

III (Slightly hazardous)

UN Number

UN3077

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

Chemically stable under standard ambient conditions

TRANSLATIONS

Language

Name

English

fenamidone

French

fenamidone

German

Fenamidone

Danish

fenamidon

Italian

fenamidone

Spanish

fenamidona

Greek

fenamidone

Polish

fenamidon

Swedish

Hungarian

fenamidon

Dutch

fenamidon

Norwegian

Record last updated:	22/05/2025
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