Temephos (Ref: OMS 786)	Last updated: 22/08/2024
(Also known as: ENT 27165; abaphos; abathion; biothion; difenphos)

---

GENERAL INFORMATION

Description	A nonsystemic organophosphorus insecticide used to control ecoparasites
Availability status	Current
Introduction & key dates	1965, introduced
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 appproved
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?	No
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)
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

Formulations

Property	Product	Manufacturer	Authorisation Route	Legal Class (GB/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	-

ENVIRONMENTAL FATE

Property		Value	Source; quality score; and other information	Interpretation
Solubility - In water at 20 °C (mg l⁻¹)		0.001	M4 M = GLEAMS Model database (Groundwater Loading Effects of Agricultural Management Systems). Dataset no longer available. 4 = Verified data	Low
Solubility - In organic solvents at 20 °C (mg l⁻¹)		9600	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Hexane	-
Melting point (°C)		30.3	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
Boiling point (°C)		-	-	-
Degradation point (°C)		-	-	-
Flashpoint (°C)		-	-	-
Octanol-water partition coefficient at pH 7, 20 °C	P	8.91 X 1004	Calculated	-
	Log P	4.95	G4 G = Extension Toxicology network database EXTOXNET. Available online but no longer updated. (click here ) 4 = Verified data	High
Fat solubility of residues	Solubility	-	-	-
	Data type	-	-	-
Density (g ml⁻¹)		1.32	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
Dissociation constant pKa) at 25 °C		-	-	-
		-
Vapour pressure at 20 °C (mPa)		9.50 X 10-03	K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data	Low volatility
Henry's law constant at 25 °C (Pa m³ mol⁻¹)		1.99 X 10-04	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)		-	-	-
Refractive Index		-	-	-
Environmental release		-

Degradation

Property		Value	Source; quality score; and other information	Interpretation
Soil degradation (days) (aerobic)	DT₅₀ (typical)	2	K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data	Non-persistent
	DT₅₀ (lab at 20 °C)	30	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	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	2	K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data	Moderately fast
	Note	-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7	Value	10	K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data	Non-persistent
	Note	-
Water-sediment DT₅₀ (days)		-	-	-
Water 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)	-	G4 G = Extension Toxicology network database EXTOXNET. Available online but no longer updated. (click here ) 4 = Verified data	Non-mobile
	Koc (mL g⁻¹)	100000
	Notes and range	-
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		-1.48	Calculated	Low leachability
Bio-concentration factor	BCF (l kg⁻¹)	2300	F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment ) 4 = Verified data 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	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat	Low
Mammals - Short term dietary NOEL	(mg kg⁻¹)	-	L2 L = Pesticide manuals and hard copy reference books / other sources 2 = Unverified data of unknown source Rat 2 yr	-
	(ppm diet)	300		-
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Birds - Acute LD₅₀ (mg kg⁻¹)		> 1200	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source 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	Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source 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		-	-	-
		-	-	-
Honeybees (Apis spp.)	Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	> 1.55	G4 G = Extension Toxicology network database EXTOXNET. Available online but no longer updated. (click here ) 4 = Verified data 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	-	-	-
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	J4 J = Pesticide Action Network database (click here ) 4 = Verified data 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	J4 J = Pesticide Action Network database (click here ) 4 = Verified data 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	R4 R = Peer reviewed scientific publications 4 = Verified data 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 - Acute 7 day EC₅₀, biomass (mg l⁻¹)		-	-	-
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)		1.4	W2 W = French database provided by ARVALIS-Institut du Végétal. Dataset no longer available. 2 = Unverified data of unknown source Unknown species	Moderate
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)		-	-	-
Mesocosm study data	NOEAEC mg l⁻¹	-	-	-
	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)		4204	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat	Low
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)		2181	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rabbit	-
Mammals - Inhalation LC₅₀ (mg l⁻¹)		4.79	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat	-
Other Mammal toxicity endpoints		Intraperitoneal LD₅₀ = 912 mg kg⁻¹	V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source Rat	-
		Subcutaneous LD₅₀ = 912 mg kg⁻¹	V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source 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	Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source	-

Health issues

Specific human health issues		Carcinogen Genotoxic Endocrine disruptor XNo, known not to cause a problem A0 A = Chromosome aberration (EFSA database) 0 = No data ; B0 B = DNA damage/repair (EFSA database) 0 = No data ; C0 C = Gene mutation (EFSA database) 0 = No data ; D0 D = Genome mutation (EFSA database) 0 = No data ; E2 E = Unspecified genotoxicity type (miscellaneous data source) 2 = Mixed/ambiguous results No data found Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant No data found ✓Yes, known to cause a problem ✓Yes, known to cause a problem Respiratory tract irritant Skin irritant Skin sensitiser No data found XNo, known not to cause a problem No data found Eye irritant Phototoxicant   ?Possibly, status not identified 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:	22/08/2024
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