Temephos (Ref: OMS 786)

Temephos (Ref: OMS 786)	Last updated: 04/09/2025
(Also known as: ENT 27165; abaphos; abathion; biothion; difenphos)

GENERAL INFORMATION

Description

A nonsystemic organophosphorus insecticide used to control ecoparasites

Examples of veterinary uses

Used to control mosquito, midge, and black fly larvae

Examples of species treated

Sheep; Cats; Dogs

Approval status

VMR 2013/2033 approval status (GB/UK)

Not approved

EU Regulatory approval status

Not approved

Chemical structure

Isomerism

None

Chemical formula

C₁₆H₂₀O₆P₂S₃

Canonical SMILES

COP(=S)(OC)OC1=CC=C(C=C1)SC2=CC=C(C=C2)OP(=S)(OC)OC

Isomeric SMILES

International Chemical Identifier key (InChIKey)

WWJZWCUNLNYYAU-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C16H20O6P2S3/c1-17-23(25,18-2)21-13-5-9-15(10-6-13)27-16-11-7-14(8-12-16)22-24(26,19-3)20-4/h5-12H,1-4H3

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Insecticide

Substance groups

Organophosphate insecticide; Organothiophosphate insecticide

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Non-systemic. Acetylcholinesterase (AChE) inhibitor.

Molecular targets

[Cholinesterase, Inhibitor]

CAS RN

3383-96-8

EC number

222-191-1

CIPAC number

340

US EPA chemical code

059001

PubChem CID

5392

CLP index number

No data found

Therapeutic Class

ATCvet Code

None allocated

Controlled Drug?

Regulation 37/2010 MRL Classification

Molecular mass

466.47

PIN (Preferred Identification Name)

O,O,O',O'-tetramethyl O,O'-(sulfanediyldi-4,1-phenylene) bis(phosphorothioate)

IUPAC name

O,O,O',O'-tetramethyl O,O'-thiodi-p-phenylene bis(phosphorothioate)

CAS name

O,O'-(thiodi-4,1-phenylene) bis(O,O-dimethyl phosphorothioate)

Forever chemical

Other status information

Marine Pollutant; Evidence of use in third world countries; PAN listed Highly Hazardous Chemical

Relevant Environmental Water Quality Standards

Physical state

Colourless crystals

Commercial

Property

Product

Manufacturer

Authorisation Route

Legal Class (GB/UK)

Availability status

Current

Introduction & key dates

1965, introduced; 2009, withdrawn UK

Example products (past and present) using this active

Coopers Assassin Sheep Dip

Intervet Australia Pty Limited

No GB authorisation for use with animals

Not applicable

Stopmos 1G

Ivorychem PTE, Singapore

No GB authorisation for use with animals

Not applicable

Formulation and application details

Commercial production

Temephos is synthesised through a multi-step chemical process involving the formation of a phosphorothioate ester. The production typically begins with the reaction of O,O-dimethyl phosphorochloridothioate with 4,4'-thiodiphenol, a compound containing two phenolic groups linked by a sulphur bridge. This condensation reaction forms the active temephos molecule.

Impact on climate of production and use

Data for the amount of life cycle GHGs produced by temephos are not available in the public domain. However, whilst estimates vary, more general data suggests that between 14 and 19 kilograms of CO₂e is emitted per kilogram of insecticide produced.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

0.001

Low

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

9600

Hexane

Melting point (°C)

30.3

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

8.91 X 10⁰⁴

Calculated

Log P

4.95

High

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.32

Dissociation constant pKa) at 25 °C

Vapour pressure at 20 °C (mPa)

9.50 X 10^-03

Low volatility

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

1.99 X 10^-04

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)

Moderately persistent

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

Note

General literature DT₅₀ approx 2 days (R3)

Manure DT₅₀ (days)

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Moderately fast

Note

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

Value

Non-persistent

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)

100000

Notes and range

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

-1.48

Calculated

Low leachability

Bio-concentration factor

BCF (l kg⁻¹)

2300

Whole fish

Threshold for concern

CT₅₀ (days)

Not available

Known soil and groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

4,4-sulfonyldiphenol

Rat (Faecal)

temephos sulfoxide

Plant; Rat (Faecal)

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

4204

Rat

Low

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat 2 yr

(ppm diet)

300

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

Birds - Acute LD₅₀ (mg kg⁻¹)

> 1200

Anas platyrhynchos

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

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

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

> 1000

Eisenia foetida

Low

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)

> 1.55

Apis mellifera

Moderate

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)

> 3.49

Oncorhynchus mykiss

Moderate

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

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

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

0.00001

Daphnia magna

High

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)

0.0040

Chironomus salinarius 24 hr

High

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)

1.4

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)

4204

Rat

Low

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

2181

Rabbit

Mammals - Inhalation LC₅₀ (mg l⁻¹)

4.79

Rat

Other Mammal toxicity endpoints

Intraperitoneal LD₅₀ = 912 mg kg⁻¹

Rat

Subcutaneous LD₅₀ = 912 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

List I; List II

Exposure Routes

Public

Dietary risks from food and drinking water are not of concern due to pattern of use

Occupational

Mammalian dose elimination route and rate

Excreted mainly unchanged in the faeces

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

No further information available

Handling issues

Property

Value and interpretation

General

Prevent generation of dust and mists
IMDG Transport Hazard Class 6.1

CLP classification 2013

Health: H302, H311, H332, H373
Environment: H400, H410

WHO Classification

III (Slightly hazardous)

UN Number

UN2811

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

Stable and non-reactive under normal conditions of use, storage and transport

TRANSLATIONS

Language

Name

English

temephos

French

temephos

German

Temephos

Danish

temephos

Italian

temefos

Spanish

temefos

Greek

Polish

temefos

Swedish

Hungarian

Dutch

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