Myclobutanil (Ref: RH 3866)

Myclobutanil (Ref: RH 3866)	Last updated: 16/03/2024
(Not known by any other names)

SUMMARY

Myclobutanil is a widely used fungicide. It is moderately toxic if ingested. It is moderately soluble in water and organic solvents and is volatile. Studies seem to show that Myclobutanil has a high potential for leaching and is moderately persistent in soil systems. Under certain conditions it may also be persistent in aquatic systems. It is moderately toxic to birds, fish, aquatic invertebrates, algae, 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 Moderate alert: Moderately persistent; GUS: Transition state; Drainflow: Slightly mobile	Ecotoxicity Moderate alert: Birds acute ecotoxicity: Moderate; 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 High alert: Endocrine disrupter

GENERAL INFORMATION

Description

A fungicide used to control Ascomycetes, Fungi Imperfecti and Basidiomycetes in a wide range of crops including table grapes

Example pests controlled

Powdery mildew; Dollar spot; Summer patch; Brown patch; Rusts; scab

Example applications

Perennial and annual crops; Turf; Landscape ornamentals; Fruit trees; Vines

Efficacy & activity

Availability status

Current

Introduction & key dates

1986, first reported; 1989, first marketed

UK regulatory status

UK COPR regulatory status

Approved

Date COPR inclusion expires

31/05/2024

UK LERAP status

Check label - may vary with formulation

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Not approved

Dossier rapporteur/co-rapporteur

UK/Spain

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

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

Australia, USA, Asia, Africa

Chemical structure

Isomerism

A chiral molecule. The technical material is an isomeric equimolar mixture of the R- and S-forms.

Chemical formula

C₁₅H₁₇ClN₄

Canonical SMILES

CCCCC(CN1C=NC=N1)(C#N)C2=CC=C(C=C2)Cl

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

HZJKXKUJVSEEFU-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C15H17ClN4/c1-2-3-8-15(9-17,10-20-12-18-11-19-20)13-4-6-14(16)7-5-13/h4-7,11-12H,2-3,8,10H2,1H3

2D structure diagram/image available?

Yes

General status

Pesticide type

Fungicide

Substance groups

Triazole fungicide; Conazole fungicide

Minimum active substance purity

925 g kg⁻¹ 1:1 racemic mixture

Known relevant impurities

EU dossier - 1-methyl-2-pyrrolidinone <1g kg⁻¹

Substance origin

Synthetic

Mode of action

Broad spectrum, systemic with protective, eradicative and curative action. Disrupts membrane function by inhibiting sterol biosynthesis.

CAS RN

88671-89-0

EC number

410-400-0

CIPAC number

442

US EPA chemical code

128857

PubChem CID

6336

CLP index number

No data found

Molecular mass

288.78

PIN (Preferred Identification Name)

IUPAC name

(RS)-2-(4-chlorophenyl)-2-(1H-1,2,4-triazol-1-ylmethyl)hexanenitrile

CAS name

α-butyl-α-(4-chlorophenyl)-1H-1,2,4-triazole-1-propanenitrile

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 crystalline solid

Related substances & organisms

myclobutanil hydrochloride

Formulations

Property

Value

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

AgriGuard
Dow AgroSciences
Landseer

Example products using this active

Eagle
Nova
Rally
Systhane 20 EW
Masalon

Formulation and application details

Often supplied as an oil suspension in water that is mixed 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)

132

Moderate

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

1020

n-Heptane

270000

Xylene

250000

Methanol

250000

Acetone

Melting point (°C)

70.9

Boiling point (°C)

390.8

Degradation point (°C)

Flashpoint (°C)

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

7.76 X 10⁰²

Calculated

Log P

2.89

Moderate

Fat solubility of residues

Solubility

Insoluble

Data type

Regulatory data based on LogP

Density (g ml⁻¹)

1.24

Dissociation constant pKa) at 25 °C

2.3

Strong acid

Vapour pressure at 20 °C (mPa)

0.198

Low volatility. If applied directly to plants, drift is a concern & mitigation is advisable

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

4.33 X 10^-04

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

Negligible

24 hr

From soil surface

Negligible

24 hr

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

203nm = 16400, 219nm = 17900, 267nm = 500, 273nm = 500, 290nm = 0

Surface tension (mN m⁻¹)

46.8

at 24°C

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

560

Very persistent

DT₅₀ (lab at 20 °C)

365

Very persistent

DT₅₀ (field)

Moderately persistent

DT₉₀ (lab at 20 °C)

1175

Very persistent

DT₉₀ (field)

365

DT₅₀ modelling endpoint

Note

EU dossier lab studies DT₅₀ range 191-1216 days, DT₉₀ range 637-1906 days, field studies DT₅₀ range 9-58 days Germany, DT₉₀ >1 year; Other sources: DT₅₀ 66 days (DW4)

Dissipation rate RL₅₀ (days) on plant matrix

Value

Note

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

4.1

Note

Published literature RL₅₀ range 2.3-10.5 days, 11 field & undercover grown crops, various matrices, n=15; Grapes in cold storage RL₅₀=92 days.

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Slow

Note

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

Value

Stable

Note

Stable pH 4 to pH 9 at 50 °C, 5 days

Water-sediment DT₅₀ (days)

626

Stable

Water phase only DT₅₀ (days)

Moderately fast

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.

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

K_oc

Notes and range

Freundlich

K_f

5.03

Slightly mobile

K_foc

517

¹/_n

0.88

Notes and range

K_f range 1.464-9.771, K_foc range 225.7-920 mL g⁻¹, ¹/_n range 0.851-0.912, Soils=5

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.99

Calculated

Transition state

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

Value

7.33 X 10^-02

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Slightly mobile

Calculated

Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk

7.6

Calculated using the Atkinson method

Below the level of concern for long-range air transport

Bio-concentration factor

BCF (l kg⁻¹)

CT₅₀ (days)

Known soil metabolites

Metabolite

Major/Minor fraction

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

Estimated maximum occurrence fraction

Notes

(3RS) 3-(4-chlorophenyl)-3-cyano-4-(1H-1,2,4-triazol-1-yl)butanoic acid

Minor fraction

0.006

(2RS) 2-(4-chlorophenyl)-5-oxo-2-(1H-1,2,4-triazol-1-ylmethyl)hexanenitrile

Minor fraction

1,2,4-triazole (Ref: CGA 71019)

Minor fraction

1H-1,2,4-triazol-1-ylacetic acid (Ref: CGA 142856)

Minor fraction

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)

(3RS) 3-(4-chlorophenyl)-3-cyano-4-(1H-1,2,4-triazol-1-yl)butanoic acid

Not relevant

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Metabolising enzymes

(3RS) 3-(4-chlorophenyl)-3-cyano-4-(1H-1,2,4-triazol-1-yl)butanoic acid

Surface water; Sediment

(2RS,5RS) 2-(4-chlorophenyl)-5-hydroxy-2-(1H-1,2,4-triazol-1-ylmethyl)hexanenitrile (Ref: RH-9090)

Animal; Plant

(2RS) 2-(4-chlorophenyl)-5-oxo-2-(1H-1,2,4-triazol-1-ylmethyl)hexanenitrile (Ref: RH-9089)

Animal; Plant

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

1600

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat

(ppm diet)

> 100

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

Rat Reproductive NOAEL

Moderate

Birds - Acute LD₅₀ (mg kg⁻¹)

510

Colinus virginianus

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

> 567 mg kg bw⁻¹ day⁻¹

Anas platyrhynchos

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

24.2

Colinus virginianus NOEC

Moderate

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

125

Lumbricus terrestris corr

Moderate

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

10.3

Eisenia foetida

Moderate

Soil micro-organisms

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

Dose: 0.73 mg kg⁻¹ soil 28 Day

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)

33.9

Apis mellifera

Moderate

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

> 33.9

Apis mellifera

Moderate

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) as % Mortality at dose 36 g ha⁻¹

11.9

Coccinella septempunctata Larva

Beneficial insects (Lacewings)

Beneficial insects (Parasitic wasps) as % Mortality at dose 36 g ha⁻¹

Aphidius rhopalosiphi corr

Beneficial insects (Predatory mites) as % Mortality at dose 36 g ha⁻¹

50.5

Typhlodromus pyri Protonymph

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)

2.0

Oncorhynchus mykiss

Moderate

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

0.2

Oncorhynchus mykiss

Moderate

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

> 4.25

Danio rerio Embryo

Moderate

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

Daphnia magna

Moderate

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

1.0

Daphnia magna

Moderate

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

Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)

0.24

Americamysis bahia EC₅₀

Moderate

Sediment dwelling organisms - Acute 96 hour LC₅₀ (mg l⁻¹)

Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l⁻¹)

4.98

Chironomus riparius 30 day

Moderate

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

10.0

Chironomus riparius

Moderate

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

> 105

Lemna gibba

Low

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

2.66

Scenedesmus subspicatus

Moderate

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

Mesocosm study data

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)

1600

Rat

Moderate

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 5.1

Rat 4 hr (nose only)

Other Mammal toxicity endpoints

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

0.025

Rat SF=100

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

0.31

Rat SF=100

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

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

0.03

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

Exposure Routes

Public

No unacceptable risks to bystanders identified

Occupational

No unacceptable risks to operators or other workers identified

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

0.1

EU Dir 89/778/EC limit

Mammalian dose elimination route and rate

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

Liver toxicant
Endocrine issues - Weak estrogen and androgen inhibition

Handling issues

Property

Value and interpretation

General

Not explosive or oxidising
IMDG Transport Hazard Class 9
Not expected to auto-ignite; Not highly flammable

CLP classification 2013

Health: H302, H319, H361d
Environment: H411

WHO Classification

II (Moderately hazardous)

UN Number

UN3077

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

myclobutanil

French

myclobutanil

German

Myclobutanil

Danish

myclobutanil

Italian

miclobutanil

Spanish

miclobutanilo

Greek

Polish

mychlobutanil

Swedish

Hungarian

miklobutanil

Dutch

Norwegian

Record last updated:	16/03/2024
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