Methoprene (Ref: OMS 1697)	Last updated: 04/09/2025
(Also known as: SAN 800; ZR-515)

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GENERAL INFORMATION

Description	A Juvenile hormone mimic insecticide with antiparasitic activity
Examples of veterinary uses	Used as a flea control on domestic dogs and cats and also as fly control on livestock
Examples of species treated	Dogs; Cats; Cattle; Horses

Approval status

VMR 2013/2033 approval status (GB/UK)	Not approved as isomer mix
EU Regulatory approval status	Not approved as isomer mix

Chemical structure

Isomerism	A chiral molecule existing as the R-form (cis) and the S-form (trans). The technical substance is an isomeric mixture but it is the S-form which is more biologically active.
Chemical formula	C₁₉H₃₄O₃
Canonical SMILES	CC(C)OC(=O)C=C(C)C=CCC(C)CCCC(C)(C)OC
Isomeric SMILES	CC(C)OC(=O)/C=C(\C)/C=C/CC(C)CCCC(C)(C)OC
International Chemical Identifier key (InChIKey)	NFGXHKASABOEEW-LDRANXPESA-N
International Chemical Identifier (InChI)	InChI=1S/C19H34O3/c1-15(2)22-18(20)14-17(4)11-8-10-16(3)12-9-13-19(5,6)21-7/h8,11,14-16H,9-10,12-13H2,1-7H3/b11-8+,17-14+
2D structure diagram/image available?	Yes

General status

Veterinary substance type	Insecticide
Substance groups	Juvenile hormone mimic insecticide
Minimum active substance purity	-
Known relevant impurities	-
Substance origin	Synthetic
Mode of action	Contact and stomach action, acts by mimicing the action of the juvenile hormone keeping the insect in an immature state
Molecular targets	[Juvenile hormone receptor complex, Agonist]
CAS RN	40596-69-8
EC number	254-993-2
CIPAC number	414
US EPA chemical code	105401
PubChem CID	5366546
CLP index number	No data found
Therapeutic Class	Antiparasitic products, insecticides & repellents: Other ecotparasiticides for topical use
ATCvet Code	QP53AX28
Controlled Drug?	No
Regulation 37/2010 MRL Classification	-
Molecular mass	310.47
PIN (Preferred Identification Name)	-
IUPAC name	isopropyl (E,E)-(RS)-11-methoxy-3,7,11-trimethyldodeca-2,4-dienoate
CAS name	(E,E)-1-methylethyl (2E,4E)-11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate
Forever chemical	-
Other status information	-
Relevant Environmental Water Quality Standards	-
Physical state	Yellow to amber coloured liquid
Related substances & organisms	S-methoprene

Commercial

Property	Value
Availability status	Current
Introduction & key dates	1975, registered USA
Example manufacturers & suppliers of products using this active now or historically	Wellmark Sandoz
Example products using this active	Altosid Dianex Kabat Manta Precor Minex
Formulation and application details	Usually supplied as an emulsifiable concentrate, suspension concentrate, briquettes or bait
Commercial production	Methoprene is synthesised through a multi-step organic process that constructs its complex isoprenoid-like structure. The production typically begins with 2,6-dimethyl-5-heptenal, which undergoes a series of reactions including reduction, etherification, and condensation to build the methoprene backbone. Key steps involve the use of reagents like sodium borohydride for reduction, n-butyllithium for alkylation, and m-chloroperoxybenzoic acid for selective oxidation. These reactions are carried out under controlled temperatures and solvent conditions, often using tetrahydrofuran or diethyl ether, to ensure high yield and stereochemical precision.
Impact on climate of production and use	Data for the amount of life cycle GHGs produced by methoprene 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)		0.52	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes	Low
Solubility - In organic solvents at 20 °C (mg l⁻¹)		-	-	-
Melting point (°C)		-	-	-
Boiling point (°C)		-	-	-
Degradation point (°C)		-	-	-
Flashpoint (°C)		136	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source (closed cup)	-
Octanol-water partition coefficient at pH 7, 20 °C	P	1.00 X 1005	Calculated	-
	Log P	5	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes	High
Fat solubility of residues	Solubility	Soluble	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	-
	Data type	Regulatory data - observed in metabolism and farm animal feeding studies	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	-
Density (g ml⁻¹)		0.92	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)		3.16	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes	Low volatility. If applied directly to plants or soil, drift is a concern & mitigation is advisable
Henry's law constant at 25 °C (Pa m³ mol⁻¹)		0.886	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	Moderately 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)	10	B3 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 3 = Unverified data of known source	Non-persistent
	DT₅₀ (lab at 20 °C)	-	-	-
	DT₅₀ (field)	10	B3 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 3 = Unverified data of known source	Non-persistent
	DT₉₀ (lab at 20 °C)	-	-	-
	DT₉₀ (field)	-	-	-
	Note	-
Manure DT₅₀ (days)		-	-	-
Aqueous photolysis DT₅₀ (days) at pH 7	Value	1	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes	Moderately fast
	Note	-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7	Value	Stable	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes	Stable
	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)	-	F3 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 ) 3 = Unverified data of known source	Slightly mobile
	Koc (mL g⁻¹)	2535
	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		0.60	Calculated	Low leachability
Bio-concentration factor	BCF (l kg⁻¹)	3400	R4 R = Peer reviewed scientific publications 4 = Verified data Edible	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
7-methoxycitronellic acid	-	Water (Aerobic)	-

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property		Value	Source; quality score; and other information	Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)		> 34600	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes 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)	> 5000		-
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Birds - Acute LD₅₀ (mg kg⁻¹)		> 2250	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes Anas platyrhynchos	Low
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)	> 1000	K3 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 3 = Unverified data of known source Apis mellifera	Low
	Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	0.2	K3 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 3 = Unverified data of known source Apis mellifera	High
	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)		> 0.76	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes 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)		0.089	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes Daphnia magna	High
Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)		0.051	F3 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 ) 3 = Unverified data of known source Daphnia magna LOEC	Moderate
Tropical Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)		-	-	-
Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)		0.106	F3 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 ) 3 = Unverified data of known source Americamysis bahia	Moderate
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)		1.33	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Desmodesmus subspicatus	Moderate
Algae - Chronic (growth rate, fresh; mg l⁻¹)		-	-	-
Mesocosm study data	NOEAEC mg l⁻¹	-	-	-
	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)		> 34600	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes Rat	Low
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)		2000	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rabbit	-
Mammals - Inhalation LC₅₀ (mg l⁻¹)		210	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source 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	-
	Occupational	-
Mammalian dose elimination route and rate		In cattle it is excreted unchanged in faeces	G3 G = Extension Toxicology network database EXTOXNET. Available online but no longer updated. (click here ) 3 = Unverified data of known source	-

Health issues

Specific human health issues		Carcinogen Genotoxic Endocrine disruptor XNo, known not to cause a problem A3 A = Chromosome aberration (EFSA database) 3 = Negative ; 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 ; E3 E = Unspecified genotoxicity type (miscellaneous data source) 3 = Negative No data found Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant XNo, known not to cause a problem XNo, known not to cause a problem XNo, known not to cause a problem Respiratory tract irritant Skin irritant Skin sensitiser ✓Yes, known to cause a problem ?Possibly, status not identified No data found Eye irritant Phototoxicant   ✓Yes, known to cause a problem No data found
General human health issues		No further information available

Handling issues

Property	Value and interpretation
General	No information available
CLP classification 2013	Health: H315, H335 Environment: H400, H410
WHO Classification	U (Unlikely to present an acute hazard)
UN Number	-
Waste disposal & packaging	-
Shelf-life, storage, stability and reactivity	-

TRANSLATIONS

Language	Name
English	methoprene
French	méthoprène
German	Methoprene
Danish	methopren
Italian	metoprene
Spanish	metoprene
Greek	-
Polish	metopren
Swedish	-
Hungarian	-
Dutch	-
Norwegian	-

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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