MCPB (Ref: MB 3046)

MCPB (Ref: MB 3046)	Last updated: 15/09/2021
(Also known as: 2,4-MCPB; L-338; MCPB acid)

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: Drainflow: Moderately mobile	Ecotoxicity Moderate alert: Birds acute ecotoxicity: Moderate; Fish acute ecotoxicity: Moderate; Fish chronic ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate; Bees acute oral ecotoxicity: Moderate; Earthworms acute ecotoxicity: Moderate	Human health High alert: Mammals chronic toxicity: High

GENERAL INFORMATION

Description

A herbicide for post-emergence control of annual and perennial broad-leaved weeds

Example pests controlled

Thistles; Docks; Buttercups; Fat hen; Shepherds purse; Nightshade; Nettles; Plantains; Ragwort; Hedge mustard; Bindweed

Example applications

Newly sown pastures; Clover seed crops; Peas; cereals undersown with ryegrass or clover

Efficacy & activity

Availability status

Current

Introduction & key dates

circa 1960

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
✓			✓		✓			✓

Additional information

Also used in

Chemical structure

Isomerism

None

Chemical formula

C₁₁H₁₃ClO₃

Canonical SMILES

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

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

LLWADFLAOKUBDR-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C11H13ClO3/c1-8-7-9(12)4-5-10(8)15-6-2-3-11(13)14/h4-5,7H,2-3,6H2,1H3,(H,13,14)

2D structure diagram/image available?

Yes

General status

Pesticide type

Herbicide

Substance group

Aryloxyalkanoic acid

Minimum active substance purity

840 g kg⁻¹

Known relevant impurities

EU dossier - free phenols <30g/Kg as 4-chloro-2-methylphenol, triethanolamine insolubles <1g kg⁻¹

Substance origin

Synthetic

Mode of action

Selective, systemic, absorbed by leaves and roots with translocation. Synthetic auxin.

CAS RN

94-81-5

EC number

202-365-3

CIPAC number

US EPA chemical code

019201

PubChem CID

7207

Molecular mass

228.67

PIN (Preferred Identification Name)

IUPAC name

4-(4-chloro-o-tolyloxy)butyric acid

CAS name

4-(4-chloro-2-methylphenoxy)butanoic acid

Other status information

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

White powder

Related substances & organisms

bentazone

Formulations

Property

Value

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

BASF
Headland
Nufarm
United Phosphorus

Example products using this active

Butoxone
Tropotox
Tropotox Plus
Thistrol

Formulation and application details

Often supplied as soluble concentrate or in liquid formulations

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

4400

High

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

313000

Acetone

169000

Dichloromethane

266

Hexane

150000

Ethanol

Melting point (°C)

Boiling point (°C)

623

(some decomposition)

Degradation point (°C)

623

Flashpoint (°C)

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

2.09 X 10⁰¹

Calculated

Log P

1.32

Low

Bulk density (g ml⁻¹)

1.233

Dissociation constant pKa) at 25 °C

4.5

Weak acid

Vapour pressure at 20 °C (mPa)

0.004

Low volatility

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

3.0 X 10^-05

Non-volatile

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

228nm = 9827, 278nm = 1714

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)

6.8

Non-persistent

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

22.6

Non-persistent

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

EU dossier Lab studies DT₅₀ range 2-11 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

2.6

Moderately fast

Note

Rapid photolysis at pH 5 to pH 9 under irradiated conditions

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

Value

Stable

Note

Stable pH 5 to pH 9, 30 days

Water-sediment DT₅₀ (days)

Fast

Water phase only DT₅₀ (days)

9.7

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

Moderately mobile

K_foc

108

¹/_n

0.819

Notes and range

EU dossier K_foc range 86-130 mL g⁻¹

pH sensitivity

Adsorption increases as pH decreases

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.64

Calculated

Low leachability

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

Value

1.03 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

MCPA (Ref: BAS 009H)

Soil

0.062

Minor fraction, Relevant

cloxyfonac

Soil

0.095

Minor fraction, Not relevant

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)

4300

Rat

Low

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat 2 year

(ppm diet)

> 100

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

Rat NOEL

High

Birds - Acute LD₅₀ (mg kg⁻¹)

282

Colinus virginianus

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

> 5000 mg kg feed⁻¹

Colinus virginianus

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

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

4.3

Oncorhynchus mykiss

Moderate

Fish - Chronic 21 day NOEC (mg l⁻¹)

Oncorhynchus mykiss

Low

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

Daphnia magna

Moderate

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)

Lemna gibba

Low

Non-target plants

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

41.0

Pseudokirchneriella subcapitata

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)

> 81.8

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)

> 263

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

4000

>
Aphidius rhopalosiphi

% Effect

Other arthropod (2)

LR₅₀ g ha⁻¹

2000

>
Typhlodromus pyri

% Effect

Soil micro-organisms

Nitrogen mineralisation: Effect noted but recovery by day 42
Carbon mineralisation: No significant adverse effect

Dose: 10 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)

4300

Rat

Low

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 1.14

Rat 4 hr

Other Mammal toxicity endpoints

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

0.01

Rat SF=100

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

0.05

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)

0.06

Rat SF=100

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

Exposure Routes

Public

Occupational

Occupational exposure may occur through dermal contact and inhalation of dust and sprays

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

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

No data found

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

Harmful or fatal if swallowed
Causes irreversible eye damage

Handling issues

Property

Value and interpretation

General

Not explosive
IMDG Transport Code is usually 9
Not expected to autoignite; Not highly flammable

CLP classification 2013

Environment: H400, H410

EC Risk Classification

N - Dangerous for the environment: R50, R53

EC Safety Classification

S60, S61

WHO Classification

II (Moderately hazardous)

UN Number

Usually 3082

Waste disposal & packaging

Packaging Group III (minor danger)

TRANSLATIONS

Language

Name

English

MCPB

French

MCPB

German

MCPB

Danish

MCPB

Italian

MCPB

Spanish

MCPB

Greek

MCPB

Polish

MCPB

Swedish

MCPB

Hungarian

MCPB

Dutch

MCPB

Record last updated:	15/09/2021
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