(Also known as: (4-chlorophenoxy)acetic acid ; PCPA; 4-CPA; 4-ChFu; 4-CPA)
SUMMARY
4-CPA is a plant growth regulator. 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.
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.
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
CLP index number
607-073-00-3
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 Class (HRAC MoA class)
P
Herbicide Resistance Class (WSSA MoA class)
19
Insecticide Resistance Class (IRAC MoA class)
Not applicable
Fungicide Resistance Class (FRAC MOA class)
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
A. H. Marks
Hockley International Ltd.
Example products using this active
Poltomat
Marks 4-CPA
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
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source
High
Solubility - In organic solvents at 20 °C (mg l⁻¹)
-
-
-
Melting point (°C)
157
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source
-
Boiling point (°C)
Decomposes before boiling
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source
-
Degradation point (°C)
-
-
-
Flashpoint (°C)
-
-
-
Octanol-water partition coefficient at pH 7, 20 °C
P
1.78 X 1002
Calculated
-
Log P
2.25
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source
Low
Fat solubility of residues
Solubility
-
-
-
Data type
-
-
-
Density (g ml⁻¹)
1.52
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
-
Dissociation constant pKa) at 25 °C
3.01
DW4 DW = Don Wauchope personal database for Pka data: Wauchope, R. D. and Edwards, J. Dissociation constants for pesticide active ingredients: a database and comparison with predicted values. Dataset is no longer available. 4 = Verified data
-
Weak acid
Vapour pressure at 20 °C (mPa)
2.40 X 10-02
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Low volatility
Henry's law constant at 25 °C (Pa m³ mol⁻¹)
6.48 X 10-08
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source
Non-volatile
Volatilisation as max % of applied dose lost
From plant surface
-
-
-
From soil surface
-
-
-
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 (days) on plant matrix
Value
-
-
-
Note
-
Dissipation rate RL₅₀ (days) 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)
-
-
-
Sediment phase only DT₅₀ (days)
-
-
-
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.
Decay in stored produce DT₅₀
-
Soil adsorption and mobility
Property
Value
Source; quality score; and other information
Interpretation
Linear
Kd (mL g⁻¹)
-
V1 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 1 = Estimated data with little or no verification
Mobile
Koc (mL g⁻¹)
18
Notes and range
Estimated
Freundlich
Kf (mL g⁻¹)
-
-
-
Kfoc (mL g⁻¹)
-
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
-
-
-
Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk
-
-
-
Bio-concentration factor
BCF (l kg⁻¹)
Low risk
Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source
Aquatic plants - Acute 7 day EC₅₀, biomass (mg l⁻¹)
-
-
-
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)
1.4
Q2 Q = Miscellaneous data from online sources 2 = Unverified data of unknown source
Unknown species
Moderate
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)
1
A2 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 2 = Unverified data of unknown source
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
Environmental fate
Warning:
Ecotoxicity
