Metalaxyl (Ref: CGA 48988)

Metalaxyl (Ref: CGA 48988)	Last updated: 12/01/2021
(Not known by any other names)

GENERAL INFORMATION

Description

A fungicide used to control diseases caused by air- and soil-borne Peronosporales in many different crops

Example pests controlled

Downy mildew; Foliar and tuber blight; Damping-off

Example applications

Many agricultural crops including tobacco, potaoes, soybean, onions, citrus, cucubits, tomatoes, cotton; Ornamentals; Turf

Efficacy & activity

Availability status

Current

Introduction & key dates

1977, first reported; 1979, first marketed

UK regulatory status

UK COPR regulatory status

Not approved

Date COPR inclusion expires

30/06/2026

UK LERAP status

Buffer probably required in UK - see product label

EC Regulation 1107/2009 (repealing 91/414)

EC Directive 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

Spain/Portugal

Date EC 1107/2009 inclusion expires

30/06/2023

EU Candidate for substitution (CfS)

Yes - non-active isomers

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

A chiral molecule that exists in the R- and S-forms

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-UHFFFAOYSA-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

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

950 g kg⁻¹

Known relevant impurities

EU dossier: 2,6-dimenthylaniline < 1 g kg⁻¹

Substance origin

Synthetic

Mode of action

Systemic with curative and protective action, acts by suppressing sporangial formation, mycelial growth and the establishment of new infectons. Disrupts fungal nucleic acid synthesis - RNA ploymerase 1.

CAS RN

57837-19-1

EC number

260-979-7

CIPAC number

365

US EPA chemical code

113501

PubChem CID

42586

Molecular mass

279.33

PIN (Preferred Identification Name)

IUPAC name

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

CAS name

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

Other status information

Potential groundwater contaminant

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

Colourless to white fine crystals

Formulations

Property

Value

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

Apron
Ridomil
Subdue

Example products using this active

Clayton
ISK Biosciences Europe SA
Syngenta
Ciba-Giegy

Formulation and application details

Foliar application. Available in a variety of different formulations including granules, wettable powders and emulsifiable concentrates.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

8400

at 22 °C pH 5.2

High

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

550000

Benzene

9100

Hexane

650000

Methanol

Miscible

Toluene

Melting point (°C)

72.0

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

Not expected to self ignite; Not highly flammable

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

5.62 X 10⁰¹

Calculated

Log P

1.75

at 25 °C

Low

Bulk density (g ml⁻¹)

1.2

Dissociation constant pKa) at 25 °C

Very strong acid

Vapour pressure at 20 °C (mPa)

0.75

Low volatility

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

1.60 X 10^-05

Non-volatile

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

Max at 206nm
No absorption > 290nm

Surface tension (mN m⁻¹)

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Moderately persistent

DT₅₀ (lab at 20 °C)

7.1

Non-persistent

DT₅₀ (field)

14.1

Non-persistent

DT₉₀ (lab at 20 °C)

28.9

Non-persistent

DT₉₀ (field)

46.7

DT₅₀ modelling endpoint

Note

EU dossier Lab studies DT₅₀ range 2.6-73 days (normalised), DT₉₀ range 13-87 days; Field studties DT₅₀ range 4.6-31 days, Dt90 range 15-102 days; Other sources: DT₅₀ 70 days (DW4)

Dissipation rate RL₅₀ on plant matrix

Value

9.2

Note

Published literature RL₅₀ range 2.5-16.0 days, 3 field & undercover grown crops, various matrices, n=3

Dissipation rate RL₅₀ on and in plant matrix

Value

5.7

Note

Published literature RL₅₀ range 0.8-22.5 days, 16 field & undercover crops, various matrices, n=31; Lab study with bentgrass, RL₅₀=100 days

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Stable

Note

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

Value

106

Persistent

Note

pH sensitive: DT₅₀ 200 days at pH 1, 115 days at pH 9, 12 days at pH 10, all at 20 °C

Water-sediment DT₅₀ (days)

Moderately fast

Water phase only DT₅₀ (days)

Stable

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

Moderately mobile

K_oc

162

Notes and range

Freundlich

K_f

2.49

Moderately mobile

K_foc

162.3

¹/_n

0.98

Notes and range

EU dossier K_f range 0.4-1.4 mL g⁻¹, K_foc range 29.6-283.8 mL g⁻¹, ¹/_n range 0.766-1.257, Soils=4; Literature data: K_f range 0.01-8.01 mL g⁻¹, K_foc range 28-284 mL g⁻¹, 1.n range 0.57-1.32, Soils = 27

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

2.06

Calculated

Transition state

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

Value

5.61 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

0.536

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Metabolising enzymes

2,6-dimethylacetanilide

Soil (Aerobic)

N-(3-hydroxy-2,6-dimethylphenyl)-N-(methoxyacetyl)-L-alanine

Water (Anaerobic)

ECOTOXICOLOGY

Property

Value

Source; quality score; and other information

Interpretation

Bio-concentration factor

BCF (l kg⁻¹)

Whole fish

Low potential

CT₅₀ (days)

Not available

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 669

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)

> 96

Rat Reproductive NOAEL

Moderate

Birds - Acute LD₅₀ (mg kg⁻¹)

1466

Anas platyrhynchos

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

> 10000 mg kg feed⁻¹

Anas platyrhynchos

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

24.6

Anas platyrhynchos

Moderate

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

0.96

Oncorhynchus mykiss

Moderate

Fish - Chronic 21 day NOEC (mg l⁻¹)

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

3.47

Daphnia magna

Moderate

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

> 1.0

Daphnia magna

Moderate

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

0.64

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)

Lemna gibba

Low

Non-target plants

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

0.42

Scenedemus subspicatus

Moderate

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

> 20

Chlorella pyrenoidosa

Low

Honeybees (Apis spp.)

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

200

Low

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

269

Low

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

Eisenia foetida

Low

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

Eisenia foetida as metalaxyl-M

Moderate

Other soil macro-organisms

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Other arthropod (1)

LR₅₀ g ha⁻¹

630

as g product ha⁻¹ (Armetil Cobre: Conc 8% metalaxyl)
Typhlodromus pyri

% Effect

Other arthropod (2)

LR₅₀ g ha⁻¹

380

as g product ha⁻¹ (Armetil Cobre: Conc 8% metalaxyl)
Aphidius rhopalosiphi

% Effect

Soil micro-organisms

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

Dose: 5.0 kg ha⁻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)

> 669

Rat

Moderate

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

5000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 3.6

Rat

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

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)

0.08

Rat SF=100

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

Exposure Routes

Public

Occupational

European MRLs

EU MRL pesticide database

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

Eye irritant

Phototoxicant

No data found

General human health issues

Moderately toxic
Liver toxicant
Not listed as a skin sensitiser in the EU but some evidence available suggesting it may be exists elsewhere
A weak inducer of cytochrome P450

Handling issues

Property

Value and interpretation

General

Not explosive

CLP classification 2013

Health: H302; H317
Environment: H412

EC Risk Classification

Xn - Harmful: R22, R43
N - Dangerous for the environment: R52, R53

EC Safety Classification

S2, S13, S24, S37, S46, S61

WHO Classification

II (Moderately hazardous)

UN Number

Waste disposal & packaging

TRANSLATIONS

Language

Name

English

metalaxyl

French

metalaxyl

German

Metalaxyl

Danish

metalaxyl

Italian

metalaxil

Spanish

metalaxil

Greek

metalaxyl

Polish

metalaksyl

Swedish

metalaxyl

Hungarian

metalaxyl

Dutch

metalaxyl

Record last updated:	12/01/2021
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