Metalaxyl-M (Ref: CGA 329351)

Metalaxyl-M (Ref: CGA 329351)	Last updated: 18/02/2021
(Also known as: mefenoxam; R-metalaxyl)

GENERAL INFORMATION

Description

A fungicide used to control diseases caused by air- and soil-borne pathogens

Example pests controlled

Foliar and tuber blight; Downey mildews; Pseudoperonospora humuli; Phytophthora infestans ; Peronospora tabacina

Example applications

Potatoes; Tomatoes; Hops; Lettuce; Vegetables; Tobacco

Efficacy & activity

Availability status

Current

Introduction & key dates

1996, first reported & introduced USA

UK regulatory status

UK COPR regulatory status

Approved

Date COPR inclusion expires

31/05/2035

UK LERAP status

Buffer probably required in UK - see product label

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

Belgium/Greece

Date EC 1107/2009 inclusion expires

31/05/2035

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
✓	✓	✓	✓	✓	✓	✓	✓	✓

Also used in

Australia, USA

Chemical structure

Isomerism

Metalaxyl-M is the biologically active enantiomer (R-form) of the isomeric compound metalaxyl

Chemical formula

C₁₅H₂₁NO₄

Canonical SMILES

CC1=C(C(=CC=C1)C)N(C(C)C(=O)OC)C(=O)COC

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

ZQEIXNIJLIKNTD-GFCCVEGCSA-N

International Chemical Identifier (InChI)

InChI=1S/C15H21NO4/c1-10-7-6-8-11(2)14(10)16(13(17)9-19-4)12(3)15(18)20-5/h6-8,12H,9H2,1-5H3/t12-/m1/s1

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
metalaxyl	Unstated isomer

General status

Pesticide type

Fungicide

Substance group

Phenylamide

Minimum active substance purity

910 g kg⁻¹

Known relevant impurities

EU dossier - 2,6-dimethyl-phenylamine; 4-methoxy-5-methyl-5H-(1,2)oxathiole 2,2-dioxide; 1-methoxy-1-oxopropan-2-yl N-(2,6-dimethylphenyl)-N-(methoxyacetyl)alaninate

Substance origin

Synthetic

Mode of action

Systemic with curative and protective action. Disrupts fungal nucleic acid synthesis - RNA ploymerase 1.

CAS RN

70630-17-0

EC number

CIPAC number

580

US EPA chemical code

PubChem CID

11150163

Molecular mass

279.33

PIN (Preferred Identification Name)

IUPAC name

methyl N-(methoxyacetyl)-N-(2,6-xylyl)-D-alaninate

CAS name

methyl N-(2,6-dimethylphenyl)-N-(methoxyacetyl)-D-alaninate

Other status information

Relevant Environmental Water Quality Standards

Herbicide Resistance Classification (HRAC)

Not applicable

Herbicide Resistance Classification (WSSA)

Not applicable

Insecticide Resistance Classification (IRAC)

Not applicable

Fungicide Resistance Classification (FRAC)

Examples of recorded resistance

Physical state

Clear to pale yellow viscous liquid with weak odour at 97.2% purity, darkens with reducing purity

Related substances & organisms

chlorothalonil

Formulations

Property

Value

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

Folio
Fubol Gold
SL567
Wakil XL

Example products using this active

Fargro
Syngenta
Clayton

Formulation and application details

Often supplied as a soluble concentrate 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)

26000

High

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

59000

n-Hexane

Miscible

Toluene

Miscible

Methanol

Miscible

Acetone

Melting point (°C)

-38.7

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

270

Flashpoint (°C)

179

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

5.13 X 10⁰¹

Calculated

Log P

1.71

Low

Bulk density (g ml⁻¹)

1.13

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

3.3

Low volatility

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

3.50 X 10^-05

Non-volatile

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

266nm = 512, 274nm = 477, no absorption 290-750nm

Surface tension (mN m⁻¹)

57.6

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

6.5

Non-persistent

DT₅₀ (lab at 20 °C)

6.5

Non-persistent

DT₅₀ (field)

14.1

Non-persistent

DT₉₀ (lab at 20 °C)

48.7

Moderately persistent

DT₉₀ (field)

46.7

DT₅₀ modelling endpoint

Note

EU dossier 2015 lab studies DT₅₀ range 1.38-73.1 days, DT₉₀ range 12.7-87.6 days, field studies DT₅₀ range 9.3-30.9 days DT₉₀ range 30.7-102.6 days

Dissipation rate RL₅₀ on plant matrix

Value

Note

Dissipation rate RL₅₀ on and in plant matrix

Value

10.8

Note

Published literature RL₅₀ range 1.6-19.8 days, 6 field crops, various matrices, n=8

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Stable

Note

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

Value

Stable

Note

Stable at all pH values

Water-sediment DT₅₀ (days)

32.1

Moderately fast

Water phase only DT₅₀ (days)

24.8

Slow

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

K_oc

Notes and range

Freundlich

K_f

1.63

Moderately mobile

K_foc

78.9

¹/_n

0.955

Notes and range

EU dossier (2015) K_f range 0.07-8.01 mL g⁻¹, K_foc range 20-284 mL g⁻¹, ¹/_n range 0.77-1.12, Soils=20

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

2.42

Calculated

Transition state

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

Value

8.40 X 10^-02

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Moderately mobile

Calculated

Key metabolites

Metabolite

Formation medium

Estimated maximum occurrence fraction

1107/2009 relevancy

N-(2,6-dimethylphenyl)-N-(methoxyacetyl)alanine (Ref: CGA 62826 (racemate))

Soil

0.404

Major fraction, Not Relevant

(R)-2-((2,6-Dimethyl-phenyl)-(2-methoxy-acetyl)-amino)-propionic acid (Ref: NOA 409045)

Soil

0.720

Major fraction; Relevant

N-(2,6-Dimethyl-phenyl)-2-methoxy-acetamide (Ref: CGA 67868)

Soil

0.06

Minor fraction; Relevant

2-(((R)-1-Carboxy-ethyl)-(2-methoxy-acetyl)-amino)-3-methyl-benzoic acid (Ref: SYN 546520)

Soil

0.04

Minor fraction; Relevant

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Metabolising enzymes

N-(2-carboxy-6-methylphenyl)-N-(methoxyacetyl)alanine (Ref: CGA 108906)
Note: CAS: 104390-56-9; LC50(fish) = 100 mg/l; LC50(Daphnia) = 100 mg/l

Plant; Soil

N-(2,6-dimethylphenyl)-N-(hydroxyacetyl)alanine methyl ester (Ref: CGA 67869)
Note: CAS 66637-79-4

N-(carboxycarbonyl)-N-(2,6-dimethylphenyl)alanine methyl ester (Ref: CGA 79353)

N-hydroxyacetyl-2,6-dimethyl-aniline (Ref: CGA 37734)
Note: CAS 29183-14-0

N-(2,6-dimethyl- 5-hydroxyphenyl)-N-(methoxyacetyl)alanine methyl ester (Ref: CGA 100255)
Note: CAS 96258-85-4

N-(2-hydroxymethyl-6-methylphenyl)-N-(methoxyacetyl)alanine methyl ester (Ref: CGA 94689)
Note: CAS 85933-49-9

N-(2-carboxy-6-methylphenyl)-N-(methoxyacetyl)alanine methyl ester (Ref: CGA 108905)

N-(2,6-dimethylphenyl) alanine (Ref: CGA 67867)

N-(carboxycarbonyl)-N-(2,6-dimethylphenyl)alanine (Ref: CGA 78532)

2,6-dimethylanilinoxoacetic acid (Ref: CGA 68124)
Note: CAS 2903-48-2

N-(3-hydroxy-2,6-dimethylphenyl)-N-(methoxyacetyl)alanine (Ref: CGA 119857)

N-(2,6-dimethylphenyl)-N-(hydroxyacetyl)alanine (Ref: CGA 107955)
Note: CAS 104390-55-8

Rat

N-methoxyacetyl-2,6-dimethyl-aniline (Ref: CGA 67868)
Note: LC50(fish) = 98.9 mg/l; LC50(Daphnia) = 158 mg/l

Water

N-(2-hydroxymethyl-6-methylphenyl)-N-(methoxyacetyl)alanine
Note: CAS 53823-88-4

ECOTOXICOLOGY

Property

Value

Source; quality score; and other information

Interpretation

Bio-concentration factor

BCF (l kg⁻¹)

Low potential

CT₅₀ (days)

Not available

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

375

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

2.5

Rat

High

(ppm diet)

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

Birds - Acute LD₅₀ (mg kg⁻¹)

981

Colinus virginianus

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

> 5620 mg kg feed⁻¹

Colinus virginianus

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

Colinus virginianus

Moderate

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

> 100

Oncorhynchus mykiss

Low

Fish - Chronic 21 day NOEC (mg l⁻¹)

9.1

Pimephales promelas

Moderate

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

> 100

Daphnia magna

Low

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

1.2

Daphnia magna as metalaxyl

Moderate

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)

69.5

Lemna gibba

Low

Non-target plants

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

Unknown species

Low

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)

> 100

Apis mellifera

Low

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

> 97.3

Apis mellifera

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)

830

Eisenia foetida

Moderate

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

35.63

Eisenia foetida

Moderate

Other soil macro-organisms

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

125

Folsomia candida

Other arthropod (1)

LR₅₀ g ha⁻¹

% Effect

-14.5

Beneficial capacity [Dose: 3.5 kg ha⁻¹]
Aphidius rhopalosiphi adult

Other arthropod (2)

LR₅₀ g ha⁻¹

% Effect

11.8

Beneficial capacity [Dose: 2.5 kg ha⁻¹, 5 applications at 14 day interval, 7 day]
Typhlodromus pyri

Soil micro-organisms

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

Dose: 6.6 mg kg⁻¹ soil 100 days

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)

375

Rat

Moderate

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 2.29

Rat 4 hr (nose only)

Other Mammal toxicity endpoints

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

0.08

Dog SF=100

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

0.5

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

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

0.08

Rat 90 day SF=100

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

Notes

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

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

No data found

General human health issues

Possible liver toxicant

Handling issues

Property

Value and interpretation

General

Not explosive or oxidising

CLP classification 2013

Health: H302, H318

EC Risk Classification

Xn - Harmful: R22, R41

EC Safety Classification

S2, S26, S39, S46

WHO Classification

NL (Not listed)

UN Number

Waste disposal & packaging

TRANSLATIONS

Language

Name

English

metalaxyl-M

French

metalaxyl-M

German

Metalaxyl-M

Danish

metalaxyl-M

Italian

metalaxil-M

Spanish

metalaxil-M; mefenoxam

Greek

metalaxyl-M

Polish

metalaksyl-M

Swedish

metalaxyl-M

Hungarian

metalaxyl-M

Dutch

methalaxyl-M

Record last updated:	18/02/2021
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