Metalaxyl (Ref: CGA 48988)

Metalaxyl (Ref: CGA 48988)	Last updated: 16/03/2024
(Not known by any other names)

SUMMARY

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: GUS: Transition state; Drainflow: Moderately mobile	Ecotoxicity Moderate alert: Birds acute ecotoxicity: Moderate; Birds chronic ecotoxicity: Moderate; Fish acute ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate; Daphnia chronic ecotoxicity: Moderate; Earthworms chronic ecotoxicity: Moderate	Human health Moderate alert: Mammals acute toxicity: Moderate; Mammals chronic toxicity: Moderate

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

Approved

Date COPR inclusion expires

30/06/2026

UK LERAP status

Check label - may vary with formulation

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

Spain/Portugal

Date EC 1107/2009 inclusion expires

30/09/2026

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
	✓		✓	✓	✓		✓	✓

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

Chemical structure

Isomerism

Metalaxyl is a 1:1 mixture of the R-enantiomer and S-enantiomer. Technical-grade metalaxyl-M consists of a minimum of 97% of the R-enantiomer and 3% of the S-enantiomer.

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	-

General status

Pesticide type

Fungicide

Substance groups

Anilide fungicide; Acylamino acid fungicide

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

CLP index number

607-425-00-6

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 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

Pale beige coloured solid

Formulations

Property

Value

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

Clayton
ISK Biosciences Europe SA
Syngenta
Ciba-Giegy
BOC Sciences

Example products using this active

Apron
Ridomil
Subdue

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)

394.3

Degradation point (°C)

Flashpoint (°C)

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

5.62 X 10⁰¹

Calculated

Log P

1.75

at 25 °C

Low

Fat solubility of residues

Solubility

Data type

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

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

1.60 X 10^-05

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

24 hr

Volatilisation is potentially a concern for short and long range air transport

From soil surface

24 hr

Volatilisation is potentially a concern for short and long range air transport

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 (days) 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 (days) 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

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

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

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

Calculated using the Atkinson method

Below the level of concern for long-range air transport

Bio-concentration factor

BCF (l kg⁻¹)

Whole fish

Low potential

CT₅₀ (days)

Not available

Known soil metabolites

Metabolite

Major/Minor fraction

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

Estimated maximum occurrence fraction

Notes

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

Major fraction

0.536

2,6-dimethylacetanilide

Aerobic

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)

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

Relevancy unknown

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Metabolising enzymes

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

Water (Anaerobic)

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

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

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

Soil micro-organisms

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

Dose: 5.0 kg ha⁻¹

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)

200

Apis mellifera

Low

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

269

Apis mellifera

Low

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)

Beneficial insects (Lacewings)

Beneficial insects (Parasitic wasps) as Mortality LR₅₀ g ha⁻¹

30.4

Aphidius rhopalosiphi

Beneficial insects (Predatory mites) as Mortality LR₅₀ g ha⁻¹

50.4

Typhlodromus pyri

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)

0.96

Oncorhynchus mykiss

Moderate

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

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

> 224.8

Danio rerio

Low

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

3.47

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)

0.64

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

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

0.42

Scenedesmus subspicatus

Moderate

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

> 20

Chlorella pyrenoidosa

Low

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

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

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

; ; ; ;

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
Not expected to auto-ignite; Not highly flammable

CLP classification 2013

Health: H302; H317
Environment: H412

WHO Classification

II (Moderately hazardous)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

Limited shelf-life

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

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