Dichlorophen

Dichlorophen	Last updated: 04/09/2025
(Also known as: antiphen; anthifen)

SUMMARY

Dichlorophen is a fungicide, herbicide, bactericide and algicide. It has a moderate aqueous solubility and, based on its chemical properties, it is unlikely to leach to groundwater. It is not usually persistent in soils. Dichlorophen has a low mammalian toxicity but is moderately toxic to fish, aquatic invertebrates and algae.

GENERAL INFORMATION

Description

A phenolic, antihelminthic veterinary drug

Examples of veterinary uses

Used to control some tapeworms including Taenia spp. and Dipylidium spp. but not Echinococcus spp.

Examples of species treated

Dogs; Cats

Approval status

VMR 2013/2033 approval status (GB/UK)

Approved - usually authorised as a veterinary medicine for general sale (AVM-GSL)

EU Regulatory approval status

Approved

Chemical structure

Isomerism

None

Chemical formula

C₁₃H₁₀Cl₂O₂

Canonical SMILES

C1=CC(=C(C=C1Cl)CC2=C(C=CC(=C2)Cl)O)O

Isomeric SMILES

Clc1cc(c(O)cc1)Cc2cc(Cl)ccc2O

International Chemical Identifier key (InChIKey)

MDNWOSOZYLHTCG-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C13H10Cl2O2/c14-10-1-3-12(16)8(6-10)5-9-7-11(15)2-4-13(9)17/h1-4,6-7,16-17H,5H2

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
dichlorophen	-

General status

Veterinary substance type

Antiparasitic, Antimicrobial, Anthelmintic

Other bioactivity & uses

Bactericide; Biocide; Preservative; Slimicide; Disinfectant; Algicide

Substance groups

Bridged diphenyl fungicide; Phenolic compound

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Contact. It is believed to act by disrupting mitochondrial function and interfering with oxidative phosphorylation in parasites and fungi

Molecular targets

[Uncoupling oxidative phosphorylation]

CAS RN

97-23-4

EC number

202-567-1

CIPAC number

325

US EPA chemical code

055001

PubChem CID

3037

CLP index number

604-019-00-0

Therapeutic Class

Antiparasitic products, insecticides & repellents: Anthelmintics

ATCvet Code

QP52AG01

Controlled Drug?

Regulation 37/2010 MRL Classification

Molecular mass

269.1

PIN (Preferred Identification Name)

2,2'-methylenebis(4-chlorophenol)

IUPAC name

4,4'-dichloro-2,2'-methylenediphenol

CAS name

2,2'-methylenebis[4-chlorophenol]

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

Colourless crystals

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1944, first patented USA

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

Sindar
Beaphar UK Ltd

Example products using this active

Preventol
Beaphar Multiwormer

Formulation and application details

Usually supplied as an emulsifiable concentrate from crop protection purposes. When used as an animal antimicrobial and antiparasitic treatment, formulations include cutaneous sprays, tablets for oral administration and shampoos

Commercial production

Dichlorophen is synthesised through a condensation reaction between p-chlorophenol and formaldehyde. In a typical procedure, equimolar amounts of these two reactants are refluxed in a water bath for about three hours. After the reaction, the mixture is added to distilled water and heated to around 80 DegC to remove any residual p-chlorophenol. Once cooled with crushed ice and stirred vigorously, the product precipitates out. This crude product is then purified by recrystallization using toluene, yielding dichlorophen.

Impact on climate of production and use

Data for the amount of life cycle GHGs produced by dichlorophen are not available in the public domain. However, whilst estimates vary, more general data suggests that between 14 and 30 kilograms of CO₂e is emitted per kilogram of pesticide produced.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

Moderate

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

800000

Acetone

530000

Ethanol

540000

Isopropanol

Melting point (°C)

177.5

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

1.70 X 10⁰³

Calculated

Log P

3.23

High

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.42

Dissociation constant pKa) at 25 °C

7.6

pKa(2) 11.6, Weak acid

Vapour pressure at 20 °C (mPa)

1.30 X 10^-05

Low volatility

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

1.17 X 10^-07

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)

Refractive Index

Environmental release

Degradation

Property

Value

Source; quality score; and other information

Interpretation

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Non-persistent

DT₅₀ (lab at 20 °C)

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

Note

Best available data

Manure DT₅₀ (days)

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

K_d (mL g⁻¹)

Non-mobile

K_oc (mL g⁻¹)

4103

Notes and range

Estimated

Freundlich

K_f (mL g⁻¹)

K_foc (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

0.43

Calculated

Low leachability

Bio-concentration factor

BCF (l kg⁻¹)

45.4

Low potential

CT₅₀ (days)

Not available

Known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

2690

Rat

Low

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat

(ppm diet)

2000

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)

Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)

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

Soil micro-organisms

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Non-target plants

Vegetative vigour ER₅₀ (g ha⁻¹)

Seedling emergence ER₅₀ (g ha⁻¹)

Honeybees (Apis 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)

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

Chronic

Notes

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 bee species (1)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Other bee species (2)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Beneficial insects (Ladybirds)

Beneficial insects (Lacewings)

Beneficial insects (Parasitic wasps)

Beneficial insects (Predatory mites)

Beneficial insects (Ground beetles)

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Temperate Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

0.54

Oncorhynchus mykiss 48 hr

Moderate

Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)

> 0.154

Pimephales promelas

Moderate

Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

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

6.2

Daphnia magna

Moderate

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

Tropical Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (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 (free-floating, fonds growth, fresh) - 7 day (mg l⁻¹)

Aquatic plants (rooted, growth rate, fresh) - 14 day (mg l⁻¹)

Algae - Acute (growth rate, fresh; mg l⁻¹) (EC₅₀)

Unknown species

Moderate

Algae - Chronic (growth rate, fresh; mg l⁻¹)

Mesocosm study data

NOEAEC mg l⁻¹

Marine bivalves

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)

2690

Rat

Low

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

1000

Mouse

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Intravenous DT₅₀ = 17.0 mg kg⁻¹

Rat

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

Low risk to Europeans as no longer approved for use

Occupational

Low risk to Europeans as no longer approved for use

Mammalian dose elimination route and rate

Well absorbed and metabolised by the liver, excreted mainly in the faeces

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

No data found

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

General human health issues

Moderately toxic

Handling issues

Property

Value and interpretation

General

No information available

CLP classification 2013

Health: H302, H319
Environment: H400, H410

WHO Classification

II (Moderately hazardous)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

dichlorophen

French

dichlorophene

German

Dichlorophen

Danish

dichlorophen

Italian

diclorofene

Spanish

diclorofen

Greek

dichlorophen

Polish

dichlorofen

Swedish

Hungarian

Dutch

dichlorofeen

Norwegian

Record last updated:	04/09/2025
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