Metazachlor (Ref: BAS 47900H)

Metazachlor (Ref: BAS 47900H)	Last updated: 18/02/2021
(Also known as: metazachlore)

GENERAL INFORMATION

Description

A residual herbicide used to control a wide range of weeds in crops, ornamental trees and shrubs

Example pests controlled

Grass weeds including meadow grass; Broad-leaved weeds

Example applications

Winter and spring OSR; Brussel spouts; Maize; Peanuts; Sugarcane; Cotton; Tobacco; White cedar; Rhododendron; Pivet; Lilac Alder; Grey willow; Spruce

Efficacy & activity

Availability status

Current

Introduction & key dates

1982

UK regulatory status

UK COPR regulatory status

Approved

Date COPR inclusion expires

31/07/2024

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

Netherlands/UK

Date EC 1107/2009 inclusion expires

31/07/2021

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

Chemical structure

Isomerism

Chemical formula

C₁₄H₁₆ClN₃O

Canonical SMILES

CC1=C(C(=CC=C1)C)N(CN2C=CC=N2)C(=O)CCl

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

STEPQTYSZVCJPV-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C14H16ClN3O/c1-11-5-3-6-12(2)14(11)18(13(19)9-15)10-17-8-4-7-16-17/h3-8H,9-10H2,1-2H3

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
metazachlor	-

General status

Pesticide type

Herbicide

Substance group

Chloroacetamide

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Ergosterol inhibitor. Inhibition of VLCFA (inhibition of cell division)

CAS RN

67129-08-2

EC number

266-583-0

CIPAC number

411

US EPA chemical code

PubChem CID

49384

Molecular mass

277.75

PIN (Preferred Identification Name)

IUPAC name

2-chloro-N-(pyrazol-1-ylmethyl)acet-2',6'-xylidide

CAS name

2-chloro-N-(2,6-dimethylphenyl)-N-(1H-pyrazol-1-ylmethyl)acetamide

Other status information

PAN listed Highly Hazardous Chemical; Potential groundwater contaminant

Relevant Environmental Water Quality Standards

Herbicide Resistance Classification (HRAC)

Herbicide Resistance Classification (WSSA)

Insecticide Resistance Classification (IRAC)

Not applicable

Fungicide Resistance Classification (FRAC)

Not applicable

Examples of recorded resistance

Physical state

Colourless crystals

Related substances & organisms

dimethenamid-P

clomazone

quinmerac

fatty alcohol ethoxylate

solvent naphtha

Formulations

Property

Value

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

Alpha Metazachlor
Nimbus CS
Rapsan 500SC
Shadow
Springbok
Sultan

Example products using this active

AgriGuard
BASF
Clayton
Makhteshim-Agan
Nufarm
Standon

Formulation and application details

Often supplied as a soluble or suspension concentrate

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

450

Moderate

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

5000

Hexane

250000

Acetone

265000

Toluene

250000

Dichloromethane

Melting point (°C)

Variable

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

3.09 X 10⁰²

Calculated

Log P

2.49

Low

Bulk density (g ml⁻¹)

1.31

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

0.093

Low volatility

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

5.9 X 10^-05

Non-volatile

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

Surface tension (mN m⁻¹)

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

8.6

Non-persistent

DT₅₀ (lab at 20 °C)

10.8

Non-persistent

DT₅₀ (field)

6.8

Non-persistent

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

EU dossier lab studies DT₅₀ range 5.5-25.3 days, field studies DT₅₀ range 2.8-21.3 days; Other data - field studies DT₅₀ range 26-114 days

Dissipation rate RL₅₀ on plant matrix

Value

Note

Dissipation rate RL₅₀ on and in plant matrix

Value

Note

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Stable

Note

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

Value

Stable

Note

Stable pH 4 to pH 9

Water-sediment DT₅₀ (days)

20.6

Fast

Water phase only DT₅₀ (days)

216

Stable

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

0.78

Mobile

K_oc

54.0

Notes and range

EU dossier K_d range 0.37-1.66 mL g⁻¹, K_oc range 29.2-73.1 mL g⁻¹, Soils=4

Freundlich

K_f

1.02

Moderately mobile

K_foc

79.6

¹/_n

0.993

Notes and range

EU dossier K_f range 0.37-2.20 mL g⁻¹, K_foc range 72.5-83.5 mL g⁻¹, ¹/_n range 0.988-0.996, Soils=4

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.75

Calculated

Low leachability

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

Value

1.08 X 10^-02

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Mobile

Calculated

Key metabolites

Metabolite

Formation medium

Estimated maximum occurrence fraction

1107/2009 relevancy

metazachlor oxalic acid (Ref: BH479-4)

Soil

0.162

Major fraction, Relevant

metazachlor sulfonic acid (Ref: BH479-8)

Soil

0.216

Major fraction, Relevant

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Metabolising enzymes

-
Note: Oral LD50 Rat=3480 mg/kg bw; Possible carcinogen

C16H19N3SO4; Metazochlor M09; 479M09

Soil; Groundwater; Surface water; Sediment

-
Note: Oral LD50 Rat between 500 & 2000 mg/kg bw; Possible carcinogen

C15H18N3SO2; Metazochlor M11; 479M011

Soil; Groundwater; Surface water; Sediment

-
Note: Oral LD50 Rat >2000 mg/kg bw

C14H13N3O5; Metazochlor M12; 479M012

Soil; Groundwater; Surface water; Sediment

ECOTOXICOLOGY

Property

Value

Source; quality score; and other information

Interpretation

Bio-concentration factor

BCF (l kg⁻¹)

Low risk

Based on LogP < 3

Low risk

CT₅₀ (days)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

3480

Rat

Low

Mammals - Short term dietary NOEL

(mg kg⁻¹)

3.6

Rat

High

(ppm diet)

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

192

Rat Reproductive NOAEL

Moderate

Birds - Acute LD₅₀ (mg kg⁻¹)

> 2000

Colinus virginianus

Low

Birds - Short term dietary (LC₅₀/LD₅₀)

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

76.5

Colinus virginianus NOEL

Moderate

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

8.5

Oncorhynchus mykiss

Moderate

Fish - Chronic 21 day NOEC (mg l⁻¹)

2.15

Oncorhynchus mykiss

Moderate

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

Daphnia magna

Moderate

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

0.1

Daphnia magna

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)

7.93

Chironomus riparius

Moderate

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

0.0023

Lemna gibba

High

Non-target plants

35.1

Lettuce Glasshouse
Seedling emergence, ER₅₀
as mL product ha⁻¹ (BAS 479 22 H: Conc 500g kg⁻¹)

219.1

Rye grass Glasshouse
Vegetative vigour, ER₅₀
as mL product ha⁻¹ (BAS 479 22 H: Conc 500g kg⁻¹)

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

0.0162

Pseudokirchneriella subcapitata

Moderate

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

0.34

Unknown species

Moderate

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)

> 72.2

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)

500

Eisenia foetida corr

Moderate

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

Other soil macro-organisms

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

205

Folsomia candida corr

Other arthropod (1)

LR₅₀ g ha⁻¹

7.5

as L product ha⁻¹ (BAS 479 22 H: Conc 500g kg⁻¹)
Aphidius rhopalosiphi

% Effect

Other arthropod (2)

LR₅₀ g ha⁻¹

7.5

as L product ha⁻¹ (BAS 479 22 H: Conc 500g kg⁻¹)
Typhlodromus pyri

% Effect

Soil micro-organisms

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

Dose: 7.5 mg kg⁻¹ 28 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)

3480

Rat

Low

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

34.5

Rat

Other Mammal toxicity endpoints

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

0.08

Rat 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)

0.2

Rat SF=100

Dermal penetration studies (%)

2.0-100.0

concentration dependent

Dangerous Substances Directive 76/464

Exposure Routes

Public

No unacceptable risks identified for bystanders

Occupational

Acceptable risks for authorised pattern of use

MRLs

European

EU MRL pesticide database

Notes

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

0.1

EU Dir 89/778/EC limit; Calc MAC=120 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

Eye irritant

Phototoxicant

No data found

General human health issues

Possible liver toxicant

Handling issues

Property

Value and interpretation

General

IMDG Transport Code is usually 9

CLP classification 2013

Health: H317, H351
Environment: H400, H410

EC Risk Classification

Xn - Harmful: R43
N - Dangerous for the environment: R50, R53

EC Safety Classification

S24, S37, S60, S61

WHO Classification

III (Slightly hazardous)

UN Number

Usually 3082

Waste disposal & packaging

Packaging Group III (minor danger)

TRANSLATIONS

Language

Name

English

metazachlor

French

metazachlore

German

Metazachlor

Danish

metazachlor

Italian

metazaclor

Spanish

metazaclor

Greek

Polish

metazachlor

Swedish

metazaklor

Hungarian

metazaklor

Dutch

metazachloor

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