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S-methoprene (Ref: SAN 810)
Last updated: 03/02/2026
(Also known as: d-methoprene; ZR 2458; methoprene)
GENERAL INFORMATION
Description
Juvenile hormone mimic insecticide used for external parasite control
Examples of veterinary uses
Topically applied to control fleas and ticks
Examples of species treated
Dogs; Cats
Approval status
VMR 2013/2033 approval status (GB/UK)
Not approved
EU Regulatory approval status
Not approved
Chemical structure
Isomerism
S-methoprene exhibits geometric and stereoisomerism. It is the (S)-enantiomer of methoprene, a chiral molecule that exists as a racemic mixture of R- and S-forms. The S-isomer is significantly more biologically active than the R-isomer, particularly in mimicking juvenile hormone effects in insects. Additionally, S-methoprene features E/Z (trans/cis) geometric isomerism due to its conjugated diene structure. The biologically active form is the trans (E) configuration, which ensures optimal binding to insect hormone receptors.
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
Ecoparasiticide
Substance groups
Juvenile hormone mimic insecticide
Minimum active substance purity
-
Known relevant impurities
-
Substance origin
Synthetic
Mode of action
A juvenile hormone mimic (terpene). 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, Binder]
CAS RN
65733-16-6
EC number
613-834-0
CIPAC number
-
US EPA chemical code
105402
PubChem CID
1711973
CLP index number
607-725-00-7
Therapeutic Class
Antiparasitic products, insecticides & repellents: Other ecotparasiticides for topical use
ATCvet Code
QP53AX28
Controlled Drug?
No
Regulation 37/2010 MRL Classification
-
Molecular mass
310.48
PIN (Preferred Identification Name)
-
IUPAC name
isopropyl (E,E)-(S)-11-methoxy-3,7,11-trimethyldodeca-2,4-dienoate
CAS name
isopropyl (2E,4E, 7S)-11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate
Global Governance status: Listed (✓) under
UK Poisons List Order 1972 Rotterdam Convention Montreal Protocol
XNo
The Poisons List Order 1972
XNo
Rotterdam Convention
XNo
Montreal Protocol
Stockholm Convention OSPAR EU Water Framework Directive
XNo
Stockholm Convention
XNo
OSPAR
XNo
EU Water Framework Directive
Relevant Environmental Water Quality Standards
-
Forever chemical
-
Other status information
-
Physical state
Pale yellow liquid
Related substances & organisms
Commercial
Property
Value
Availability status
Current
Introduction & key dates
1975, introduced USA
Example manufacturers & suppliers of products using this active now or historically
  • Wellmark International
  • Chr. Olesen Group, Europe
  • Henan Tianfu Chemical China
Example products using this active
  • Biopren-BM
  • Altosid
  • Apex
  • Diacon II
  • Pharaoh's Ant Colony Eliminator
  • Precor
Formulation and application details
A variety of formulations are available including briquets, granules, liquid concentrates, topical spot-on treatments, aerosols, and foggers
Commercial production
The production of S-methoprene involves a multi-step organic synthesis starting from optically active precursors. One established method begins with (+)-dihydromyrcene, which undergoes selective hydroalumination followed by oxidation to yield S-(–)-citronellol. This intermediate is further oxidised to S-(–)-citronellal, which reacts with allylmagnesium chloride to form a key alcohol. Subsequent steps include Smidt-Moiseev oxygenation, dehydration, and Grignard reactions to build the conjugated diene ester backbone. The final transformation involves Brown solvomercuration-reduction in methanol, yielding S-methoprene with high stereochemical purity and biological activity.
Impact on climate of production and use
Data for the amount of life cycle GHGs produced by S-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 at pH 7 (mg l⁻¹)
0.515
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)
100
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID )
3 = Unverified data of known source
 -
Degradation point (°C)
- - -
Flashpoint (°C)
96
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 1006 Calculated -
Log P
6.0
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
 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)
0.924
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)
3.15
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)
457
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
Edible		 Threshold for concern
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)
> 5000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rat		 Low
Mammals - Short Term Oral NOAEL (mg kg⁻¹ bw d⁻¹)
100
A5 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 )
5 = Verified data used for regulatory purposes
Dog		 Moderate
Mammals - Long Term (Chronic) Oral 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 (mg kg⁻¹ bw d⁻¹)
- - -
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)
- - -
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹ dw soil)
> 1000
C3 C = AGRITOX dataset. Dataset is no longer available.
3 = Unverified data of known source
 Low
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹ dw soil)
- - -
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)
< 2.0
Q2 Q = Miscellaneous data from online sources
2 = Unverified data of unknown source
 Moderate
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)
- - -
Beneficial insects (Butterflies)
Contact
- - -
Notes
-
Oral
- - -
Notes
-
Aquatic ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Temperate Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
0.76
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Oncorhynchus mykiss		 Moderate
Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)
0.048
P4 P = Other non-EU, UK or US Governments and Regulators
4 = Verified data
Pimephales promelas 37 day		 Moderate
Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
- - -
Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)
0.36
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Daphnia magna		 Moderate
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)
> 5000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rat		 Low
Mammals - Short Term Oral NOAEL (mg kg⁻¹ bw d⁻¹)
100
A5 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 )
5 = Verified data used for regulatory purposes
Dog		 Moderate
Mammals - Long Term (Chronic) Oral NOAEL (mg kg⁻¹ bw d⁻¹)
- - -
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
> 5000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rat		 -
Mammals - Inhalation LC₅₀ (mg l⁻¹)
5.19
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)
0.05
A5 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 )
5 = Verified data used for regulatory purposes
 -
ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)
None allocated
A5 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 )
5 = Verified data used for regulatory purposes
 -
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
Eliminated in the urine, faeces, and breath with ~70% lost within 5 days
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
 -
Health issues
Specific human health issues (hazard-based)
Carcinogen
Genotoxic
Endocrine disruptor
No data found
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
No data found No data found
XNo, known not to cause a problem
Respiratory tract irritant Skin irritant Skin sensitiser
No data found
?Possibly, status not identified
 No data found
Eye irritant Phototoxicant  
XNo, known not to cause a problem
 No data found  
General human health issues
No further information available
Handling issues
Property
Value and interpretation
General
Not highly flammable up to 263 DegC
CLP classification 2013
Handling: GHS09
Environment: 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
S-methoprene
French
-
German
-
Danish
-
Italian
-
Spanish
-
Greek
-
Polish
S-metopren
Swedish
-
Hungarian
-
Dutch
-
Norwegian
-
Record last updated: 03/02/2026
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

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