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Prallethrin (Ref: OMS 3033)
Last updated: 25/05/2025
(Also known as: S-4068SF; d-prallethrin)
GENERAL INFORMATION
Description
A synthetic pyrethroid with fast knock-down activity against various insect pests
Availability status
Current
Introduction & key dates
1988, introduced Japan
Examples of veterinary uses
Use to control insect pests on domestic pets and pet bedding
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
Prallethrin is a complex chiral molecule. The technical material is an isomeric mixture of 8 stereoisomers but consists mainly of [1R,trans; S] and [1R,cis; S] isomers in a ratio of approximately 4:1..
Chemical formula
C₁₉H₂₄O₃
Canonical SMILES
CC1=C(C(=O)CC1OC(=O)C2C(C2(C)C)C=C(C)C)CC#C
Isomeric SMILES
-
International Chemical Identifier key (InChIKey)
SMKRKQBMYOFFMU-UHFFFAOYSA-N
International Chemical Identifier (InChI)
InChI=1S/C19H24O3/c1-7-8-13-12(4)16(10-15(13)20)22-18(21)17-14(9-11(2)3)19(17,5)6/h1,9,14,16-17H,8,10H2,2-6H3/t14-,16?,17+/m0/s1
2D structure diagram/image available?
Yes
General status
Veterinary substance type
Insecticide
Substance groups
Pyrethroid insecticide; Pyrethroid ester insecticide
Minimum active substance purity
>900 g/Kg
Known relevant impurities
-
Substance origin
Synthetic
Mode of action
Contact, with rapid knock down effect, acts on the insects nervous system. Sodium channel modulator.
Molecular targets
[Sodium channel, Modulator]
CAS RN
23031-36-9
EC number
245-387-9
CIPAC number
743
US EPA chemical code
128722
PubChem CID
9839306
CLP index number
607-431-00-9
Therapeutic Class
-
ATCvet Code
None allocated
Controlled Drug?
No
Regulation 37/2010 MRL Classification
-
Molecular mass
300.40
PIN (Preferred Identification Name)
(1E)-2-methyl-4-oxo-3-(prop-2-yn-1-yl)cyclopent-2-en-1-yl (1E,3E)-2,2-dimethyl-3-(2-methylprop-1-en-1-yl)cyclopropane-1-carboxylate
IUPAC name
(RS)-2-methyl-4-oxo-3-prop-2-ynylcyclopent-2-enyl (1RS,3RS;1RS,3SR)-2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylate
CAS name
2-methyl-4-oxo-3-(2-propynyl)-2-cyclopenten-1-yl 2,2-dimethyl-3-(2-methyl-1-propenyl)cyclopropanecarboxylate
Other status information
PAN listed Highly Hazardous Chemical
Relevant Environmental Water Quality Standards
-
Physical state
Yellowish-brown oily liquid
Formulations
Property
Product
Manufacturer
Authorisation Route
Legal Class (GB/UK)
Example products (past and present) using this active
- - - -
Formulation and application details
-
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
8.03
B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here )
4 = Verified data
 Low
Solubility - In organic solvents at 20 °C (mg l⁻¹)
500000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Hexane		 -
500000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Methanol		 -
500000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Xylene		 -
Melting point (°C)
-25
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID )
3 = Unverified data of known source
 -
Boiling point (°C)
313.5
E3 E = Manufacturers safety data sheets
3 = Unverified data of known source
 -
Degradation point (°C)
- - -
Flashpoint (°C)
139
E3 E = Manufacturers safety data sheets
3 = Unverified data of known source
(Pensky-Martens closed test)		 -
Octanol-water partition coefficient at pH 7, 20 °C
P
3.09 X 1004 Calculated -
Log P
4.49
B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here )
4 = Verified data
 High
Fat solubility of residues
Solubility
- - -
Data type
- - -
Density (g ml⁻¹)
1.03
E3 E = Manufacturers safety data sheets
3 = Unverified data of known source
 -
Dissociation constant pKa) at 25 °C
- - -
-
Vapour pressure at 20 °C (mPa)
0.64
R4 R = Peer reviewed scientific publications
4 = Verified data
25°C		 Low volatility. If applied directly to plants, drift is a concern & mitigation is advisable
Henry's law constant at 25 °C (Pa m³ mol⁻¹)
0.010
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)
- - -
DT₅₀ (lab at 20 °C)
- - -
DT₅₀ (field)
- - -
DT₉₀ (lab at 20 °C)
- - -
DT₉₀ (field)
- - -
Note
-
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
Kd (mL g⁻¹)
- - -
Koc (mL g⁻¹)
-
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
- - -
Bio-concentration factor
BCF (l kg⁻¹)
- - -
CT₅₀ (days)
- -
Known metabolites

None

ECOTOXICOLOGY
Terrestrial ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
460
B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here )
4 = Verified data
Rat		 Moderate
Mammals - Short term dietary NOEL
(mg kg⁻¹)
- - -
(ppm diet)
- -
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)
- - -
Birds - Acute LD₅₀ (mg kg⁻¹)
> 2000
B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here )
4 = Verified data
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
- - -
- - -
Honeybees (Apis spp.)
Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
0.026
B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here )
4 = Verified data
Apis mellifera		 High
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
[The residual time to 25% mortality (RT25) value for honeybees is 3 hrs - USEPA data]
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)
0.012
B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here )
4 = Verified data
Oncorhynchus mykiss		 High
Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)
> 0.003
P4 P = Other non-EU, UK or US Governments and Regulators
4 = Verified data
Oncorhynchus mykiss 61 day		 High
Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
- - -
Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)
0.0062
B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here )
4 = Verified data
Daphnia magna		 High
Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)
> 0.00065
P4 P = Other non-EU, UK or US Governments and Regulators
4 = Verified data
Daphnia magna		 High
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, growth) - Acute 7 day EC₅₀, biomass (mg l⁻¹)
- - -
Aquatic plants (rooted, growth) - Acute 14 day EC₅₀, biomass (mg l⁻¹)
- - -
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)
- - -
Algae - Chronic 96 hour NOEC, growth (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)
Intermediate (class II) - -
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
460
B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here )
4 = Verified data
Rat		 Moderate
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
5000
B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here )
4 = Verified data
Rat		 -
Mammals - Inhalation LC₅₀ (mg l⁻¹)
0.29
B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here )
4 = Verified data
Rat 4 hr		 -
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
- - -
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
;
E0 E = Unspecified genotoxicity type (miscellaneous data source)
0 = No data
 No data found
Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant
XNo, known not to cause a problem
XNo, known not to cause a problem
 No data found
Respiratory tract irritant Skin irritant Skin sensitiser
No data found
XNo, known not to cause a problem
 No data found
Eye irritant Phototoxicant  
XNo, known not to cause a problem
 No data found  
General human health issues
Toxic if ingested or inhaled
Handling issues
Property
Value and interpretation
General
IMDG Transport Hazard Class 6.1
CLP classification 2013
Health: H302, H331
Environment: H400, H410
WHO Classification
II (Moderately hazardous)
UN Number
UN2811
Waste disposal & packaging
Packaging Group I (great danger)
Shelf-life, storage, stability and reactivity
-
TRANSLATIONS
Language
Name
English
prallethrin
French
-
German
-
Danish
-
Italian
-
Spanish
praletrin
Greek
-
Polish
-
Swedish
-
Hungarian
-
Dutch
-
Norwegian
-
Record last updated: 25/05/2025
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