MCPA (Ref: BAS 009H)

MCPA (Ref: BAS 009H)	Last updated: 17/02/2021
(Also known as: metaxon; BAS 101H; BAS 141H; MCP)

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 High alert: GUS: High leachability; Drainflow: Mobile	Ecotoxicity Moderate alert: Birds acute ecotoxicity: Moderate; Birds chronic ecotoxicity: Moderate; Fish acute ecotoxicity: Moderate; Fish chronic ecotoxicity: Moderate; Earthworms acute ecotoxicity: Moderate	Human health Moderate alert: Mammals acute toxicity: Moderate; Possible Reproduction/development effects

GENERAL INFORMATION

Description

A herbicide for control of annual and perennial weeds in cereals and other crops. Can also be a pesticide transformation product.

Example pests controlled

Annual and perennial broad-leaved weeds including Charlock, Wild radish, Dandylion, Capeweed, Fat hen and Hedge mustards

Example applications

Wheat; Oats; Tritical; Rye; Establish grass; Lindseed; Asparagus

Efficacy & activity

Availability status

Current

Introduction & key dates

circa 1950

UK regulatory status

UK COPR regulatory status

Approved

Date COPR inclusion expires

31/10/2024

UK LERAP status

None

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

Poland/Netherlands

Date EC 1107/2009 inclusion expires

31/10/2021

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

Australia, USA

Chemical structure

Isomerism

None

Chemical formula

C₉H₉ClO₃

Canonical SMILES

CC1=C(C=CC(=C1)Cl)OCC(=O)O

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

WHKUVVPPKQRRBV-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C9H9ClO3/c1-6-4-7(10)2-3-8(6)13-5-9(11)12/h2-4H,5H2,1H3,(H,11,12)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
MCPA	-

General status

Pesticide type

Herbicide, Metabolite

Metabolite Type

Soil

Substance group

Aryloxyalkanoic acid

Minimum active substance purity

930 mg kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

Selective, systemic with translocation. Synthetic auxin.

CAS RN

94-74-6

EC number

202-360-6

CIPAC number

US EPA chemical code

030501

PubChem CID

7204

Molecular mass

200.62

PIN (Preferred Identification Name)

IUPAC name

4-chloro-o-tolyloxyacetic acid

CAS name

(4-chloro-2-methylphenoxy)acetic acid

Other status information

Potential groundwater contaminant

Relevant Environmental Water Quality Standards

UK Environment Agency non-statutory standard for the protection of freshwater aquatic life pH <7: 12 µg l⁻¹, pH >7 80 µg l⁻¹ as annual average; pH <7: 120 µg l⁻¹, pH >7 800 µg l⁻¹ as max acceptable conc. For salt water 80 µg l⁻¹ as annual average, 800 µg l⁻¹ as max acceptable conc. Non-statutory WHO drinking water guideline 0.002 mg l⁻¹

Herbicide Resistance Classification (HRAC)

Herbicide Resistance Classification (WSSA)

Insecticide Resistance Classification (IRAC)

Not applicable

Fungicide Resistance Classification (FRAC)

Not applicable

Examples of recorded resistance

Raphanus raphanistrum, Sisymbrium orientale

Physical state

White crystalline powder

Related substances & organisms

bentazone

clopyralid

dicamba

2,4-DB

linuron

iron sulphate

Can be a metabolite of:

Parent

Formation medium

Estimated maximum occurrence fraction

1107/2009 relevancy

MCPB

Soil

0.062

Minor fraction, Relevant

MCPA-thioethyl

Soil

0.66

Major fraction, Relevant

Formulations

Property

Value

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

Agritox
Agroxone
Cedar
Esteem
GoLow Power
Polo
Relay P
Spear
Tropotox Plus

Example products using this active

BASF
Bayer Environ
Dow AgroSciences
DuPont
Headland Agrochemicals
Luxan
Nufarm
Scotts

Formulation and application details

Often supplied as soluble concentrate, wettable powder or emulsifiable concentrate

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

29390

High

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

323

Hexane

289300

Ethyl acetate

775600

Methanol

26500

Toluene

Melting point (°C)

116

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

290

Flashpoint (°C)

Not expected to self ignite; Not highly flammable

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

1.55 X 10^-01

Calculated

Log P

-0.81

Low

Bulk density (g ml⁻¹)

1.41

Dissociation constant pKa) at 25 °C

3.73

Weak acid

Vapour pressure at 20 °C (mPa)

0.4

Low volatility

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

5.50 X 10^-05

Non-volatile

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

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)

Non-persistent

DT₅₀ (lab at 20 °C)

Non-persistent

DT₅₀ (field)

Non-persistent

DT₉₀ (lab at 20 °C)

at 25 °C

Moderately persistent

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

EU dossier lab studies DT₅₀ range 7-41 days

Dissipation rate RL₅₀ on plant matrix

Value

Note

Dissipation rate RL₅₀ on and in plant matrix

Value

4.2

Note

Published literature RL₅₀ range 2.9-6.2 days, 5 field crops, various matrices, n=6

Aqueous photolysis DT₅₀ (days) at pH 7

Value

0.05

Fast

Note

Rapid DT₅₀ ~ 1 hour pH 5 to pH 9 at 25 °C in test conditions, DT₅₀ 25.4 days in natural sunlight pH 5

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

Value

Stable

Note

Stable pH 5 to pH 9 at 25 °C

Water-sediment DT₅₀ (days)

Fast

Water phase only DT₅₀ (days)

13.5

Moderately fast

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

K_oc

Notes and range

Freundlich

K_f

0.94

Mobile

K_foc

¹/_n

0.68

Notes and range

(1) EU dossier K_f range 0.05-1.99 mL g⁻¹; K_foc range 38-157 mL g⁻¹, ¹/_n range 0.50-0.72; Soils=8; (2) Mean of 2 Norweigan soils. Fine sandy loam - Sand 49% Silt 46% Clay 5% oc=1.4% pH=6.3 K_f=1.41 1/Soils=0.74; Loam - Sand 36% Silt 45% Clay 19% OC=2.5% pH=5.5 K_f=1.50 ¹/_n=0.81 [R4]

pH sensitivity

Less adsorption as pH increases

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

2.98

Calculated

High leachability

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

Value

2.39 X 10^-01

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

2-methyl-4-chlorophenol

Soil

0.09

Minor fraction, Relevant

cloxyfonac

Soil

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)

962

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat

High

(ppm diet)

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

Birds - Acute LD₅₀ (mg kg⁻¹)

234

Colinus virginianus

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

> 983 mg kg bw⁻¹ day⁻¹

Colinus virginianus

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

93.2

Colinius virginianus NOEC

Moderate

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

> 72

Oncorhynchus mykiss

Moderate

Fish - Chronic 21 day NOEC (mg l⁻¹)

Pimephales promelas

Low

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

> 190

Daphnia magna

Low

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

Daphnia magna

Low

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)

0.152

Lemna gibba IC50

Moderate

Non-target plants

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

79.8

Pseudokirchneriella subcapitata

Low

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

Unknown species

Low

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)

> 200

Apis mellifera

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)

325

Eisenia foetida

Moderate

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

Other soil macro-organisms

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Other arthropod (1)

LR₅₀ g ha⁻¹

% Effect

100

Mortality [Dose: 2.1 L/ha]
Aphidius rhopalosiphi

Other arthropod (2)

LR₅₀ g ha⁻¹

% Effect

Mortality [Dose: 2.0 L/ha]
Typhlodromus pyri

Soil micro-organisms

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

Dose: 10x field rate

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)

962

Rat

Moderate

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

4000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 6.36

Rat 4 hr

Other Mammal toxicity endpoints

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

0.05

Rat SF=100

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

0.15

Rabbit 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)

0.04

Rat SF=100

Dermal penetration studies (%)

2.2-2.5

concentration dependent

Dangerous Substances Directive 76/464

List II

Exposure Routes

Public

May be absorbed through the skin

Occupational

Occupational exposure may occur through inhalation and dermal contact

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

; ; ; ;

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

Highly toxic
May cause hypotension
Possible liver toxicant

Handling issues

Property

Value and interpretation

General

IMDG Transport Code is usually 9

CLP classification 2013

Health: H302, H315, H318
Environment: H400, H410

EC Risk Classification

Xn - Harmful: R22, R41
Xi - Irritant: R38
N - Dangerous for the environment: R50, R53

EC Safety Classification

S2, S26, S37, S39, S60, S61

WHO Classification

II (Moderately hazardous)

UN Number

Usually 2765 or 3082

Waste disposal & packaging

Packaging Group III (minor danger)

TRANSLATIONS

Language

Name

English

MCPA

French

MCPA

German

MCPA

Danish

MCPA

Italian

MCPA

Spanish

MCPA

Greek

MCPA

Polish

MCPA

Swedish

MCPA

Hungarian

MCPA

Dutch

MCPA

Record last updated:	17/02/2021
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