(4-chlorophenoxy)acetic acid

(4-chlorophenoxy)acetic acid	Last updated: 12/01/2021
(Also known as: (4-chlorophenoxy)acetic acid ; PCPA; 4-CPA; 4-ChFu; 4-CPA)

SUMMARY

4-CPA is a plant growth regulator that does not have approval for use in the EU. It is highly soluble in water and is quite volatile. Little is known about its persistence in soil and aquatic systems. It is moderately toxic to mammals and has a high potential for bioaccumulation. It is also a recognised irritant. It is moderately toxic to birds, honeybees and most aquatic organisms. However, it has a relatively low toxicity to fish.

GENERAL INFORMATION

Description

A plant growth regulator used fruit setting and thining

Example pests controlled

Growth - in terms of thinging and fruit set

Example applications

Tomatoes; Grapes

Efficacy & activity

Availability status

Current

Introduction & key dates

Current

UK regulatory status

UK COPR regulatory status

Not approved

Date COPR inclusion expires

Expired

UK LERAP status

Not applicable

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Not approved

Dossier rapporteur/co-rapporteur

Not applicable

Date EC 1107/2009 inclusion expires

Expired

EU Candidate for substitution (CfS)

Not applicable

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

None

Chemical formula

C₈H₇ClO₃

Canonical SMILES

C1=CC(=CC=C1OCC(=O)O)Cl

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

SODPIMGUZLOIPE-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C8H7ClO3/c9-6-1-3-7(4-2-6)12-5-8(10)11/h1-4H,5H2,(H,10,11)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
(4-chlorophenoxy)acetic acid	-

General status

Pesticide type

Plant growth regulator, Herbicide

Substance group

Auxin

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Auxin-transport inhibitor. Absorbed by tissue and translocated to roots

CAS RN

122-88-3

EC number

204-581-3

CIPAC number

291

US EPA chemical code

019401

PubChem CID

26229

Molecular mass

186.59

PIN (Preferred Identification Name)

(4-chlorophenoxy)acetic acid

IUPAC name

4-chlorophenoxyacetic acid

CAS name

(4-chlorophenoxy)acetic acid

Other status information

Relevant Environmental Water Quality Standards

Herbicide Resistance Classification (HRAC)

Not known

Herbicide Resistance Classification (WSSA)

Not known

Insecticide Resistance Classification (IRAC)

Not applicable

Fungicide Resistance Classification (FRAC)

Not applicable

Examples of recorded resistance

Physical state

Off-white crystalline solid

Formulations

Property

Value

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

Poltomat
Marks 4-CPA

Example products using this active

A. H. Marks
Hockley International Ltd.

Formulation and application details

Available in a range of formulations including aerosols, liquids and tablets

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

957

High

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

Melting point (°C)

157

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

Flashpoint (°C)

Not expected to self ignite; Not highly flammable

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

1.78 X 10⁰²

Calculated

Log P

2.25

Low

Bulk density (g ml⁻¹)

1.52

Dissociation constant pKa) at 25 °C

3.01

Weak acid

Vapour pressure at 20 °C (mPa)

2.40 X 10^-02

Low volatility

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

6.48 X 10^-08

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)

DT₅₀ (lab at 20 °C)

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

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

Note

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

Value

Note

Water-sediment DT₅₀ (days)

Water phase only DT₅₀ (days)

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

Mobile

K_oc

Notes and range

Estimated

Freundlich

K_f

K_foc

¹/_n

Notes and range

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

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

Value

Cannot be calculated

Note

Potential for particle bound transport index

Potential for loss via drain flow

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Metabolising enzymes

centrophenoxine

Plant

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)

850

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

(ppm diet)

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

Birds - Acute LD₅₀ (mg kg⁻¹)

Birds - Short term dietary (LC₅₀/LD₅₀)

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

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

> 180

Lepomis macrochirus

Low

Fish - Chronic 21 day NOEC (mg l⁻¹)

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

> 40

Daphnia magna

Moderate

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

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)

Non-target plants

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

1.4

Unknown species

Moderate

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

Unknown species

Moderate

Honeybees (Apis spp.)

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

> 100

Low

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

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)

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

Other arthropod (2)

LR₅₀ g ha⁻¹

% Effect

Soil micro-organisms

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)

850

Rat

Moderate

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

2200

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

10.6

Rat

Other Mammal toxicity endpoints

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

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

AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)

AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

Exposure Routes

Public

Exposure from air or water very low as it is usually used inside
Small risk of dietary exposure
Source: US EPA

Occupational

Low risk of exposure during handling
Source: US EPA

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

; ; ; ;

No data found

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

Potential irritant
Potential kidney toxicant

Handling issues

Property

Value and interpretation

General

IMDG Transport Code is usually 8

CLP classification 2013

Health: H302

EC Risk Classification

Xn - Harmful: R22

EC Safety Classification

WHO Classification

II (Moderately hazardous)

UN Number

Usually 3265

Waste disposal & packaging

Packaging Group III (minor danger)

TRANSLATIONS

Language

Name

English

(4-chlorophenoxy)acetic acid

French

acide 4 chlorophenoxyacetique

German

4-CPA

Danish

4-CPA

Italian

4-CPA (acido 4-clorofenossiacetico =PCPA)

Spanish

4-CPA

Greek

Polish

4-CPA

Swedish

Hungarian

4-CPA

Dutch

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