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Allethrin (Ref: FMC 249)
Last updated: 24/08/2024
(Also known as: palléthrine; S-bioallethrin; toluen-disocianato; esdepallethrine; d-allethrolone chrysanthemumate)

SUMMARY
Allethrin is a pyrethroid insecticide mostly used in amenity and domestic situations. It has a low aqueous solubility, is volatile and, based on its chemical properties, would not be expected to leach to groundwater. It tends to be moderately persistent in most soil systems. Allethrin is moderately toxic to mammals and a recognised irritant. Whilst it is not highly toxic to birds it is moderately toxic to fish, honeybees and earthworms.
GENERAL INFORMATION
Description
A pyrethroid insecticide used in veterinary medicine to control parasites
Availability status
Current
Introduction & key dates
1949, first introduced; circa 1954, first registered Japan
Examples of veterinary uses
Used to control general livestock insect pests as well as fleas and ticks in domestic animals
Examples of species treated
Cattle; Cats; Dogs
Approval status
VMR 2013/2033 approval status (GB/UK)
Not approved
EU Regulatory approval status
Not approved
Chemical structure
Isomerism
A chiral molecule. Allethrin is a isomeric mixture of 8 stereoisomers.
Chemical formula
C₁₉H₂₆O₃
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)
ZCVAOQKBXKSDMS-UHFFFAOYSA-N
International Chemical Identifier (InChI)
InChI=1S/C19H26O3/c1-7-8-13-12(4)16(10-15(13)20)22-18(21)17-14(9-11(2)3)19(17,5)6/h7,9,14,16-17H,1,8,10H2,2-6H3
2D structure diagram/image available?
Yes
General status
Veterinary substance type
Antiparasitic
Substance groups
Pyrethroid insecticide
Minimum active substance purity
93%
Known relevant impurities
-
Substance origin
Synthetic
Mode of action
Stomach and respiratory action, non-systemic, paralyses insects before killing them.
Molecular targets
[Sodium & Chloride channels, Blocker]
CAS RN
584-79-2
EC number
209-542-4
CIPAC number
267
US EPA chemical code
004001/004003
PubChem CID
11442
CLP index number
006-025-00-3
Therapeutic Class
Antiparasitic products, insecticides & repellents: Pyrethrins & pyrethroids
ATCvet Code
QP53AC
Controlled Drug?
No
Regulation 37/2010 MRL Classification
-
Molecular mass
302.41
PIN (Preferred Identification Name)
(1E)-2-methyl-4-oxo-3-(prop-2-en-1-yl)cyclopent-2-en-1-yl (1?,3?)-2,2-dimethyl-3-(2-methylprop-1-en-1-yl)cyclopropane-1-carboxylate
IUPAC name
1RS)-3-allyl-2-methyl-4-oxocyclopent-2-enyl (1RS,3RS;1RS,3SR)-2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylate
CAS name
2-methyl-4-oxo-3-(2-propenyl)-2-cyclopenten-1-yl 2,2-dimethyl-3-(2-methyl-1-propenyl)cyclopropanecarboxylate
Other status information
-
Relevant Environmental Water Quality Standards
-
Physical state
Viscous amber liquid
Related substances & organisms
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)
0.0001
G4 G = Extension Toxicology network database EXTOXNET. Available online but no longer updated. (click here )
4 = Verified data
Low
Solubility - In organic solvents at 20 °C (mg l⁻¹)
Miscible
R3 R = Peer reviewed scientific publications
3 = Unverified data of known source
Acetone
-
Miscible
R3 R = Peer reviewed scientific publications
3 = Unverified data of known source
Ethanol
-
655000
E3 E = Manufacturers safety data sheets
3 = Unverified data of known source
Hexane
-
Melting point (°C)
- - -
Boiling point (°C)
281.5
E3 E = Manufacturers safety data sheets
3 = Unverified data of known source
-
Degradation point (°C)
- - -
Flashpoint (°C)
87
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
-
Octanol-water partition coefficient at pH 7, 20 °C
P
9.12 X 1004 Calculated -
Log P
4.96
P4 P = Other non-EU, UK or US Governments and Regulators
4 = Verified data
High
Fat solubility of residues
Solubility
- - -
Data type
- - -
Density (g ml⁻¹)
1.01
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)
0.78
R4 R = Peer reviewed scientific publications
4 = Verified data
at 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)
6.20 X 10-07
Q3 Q = Miscellaneous data from online sources
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)
60
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 (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
-
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
-
Note
Decomposes rapidly in UV light
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7
Value
-
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
-
Note
Hydrolysis occurs only under alkaline conditions
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)
-
DW3 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.
3 = Unverified data of known source
Slightly mobile
Koc (mL g⁻¹)
1400
Notes and range
Other sources: 9500 mL g⁻¹ (CB2)
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
1.52 Calculated Low leachability
Bio-concentration factor
BCF (l kg⁻¹)
200
R3 R = Peer reviewed scientific publications
3 = Unverified data of known source
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)
685
G4 G = Extension Toxicology network database EXTOXNET. Available online but no longer updated. (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)
> 2030
G4 G = Extension Toxicology network database EXTOXNET. Available online but no longer updated. (click here )
4 = Verified data
Colinus virginianus
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)
> 1000
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
Unknown species
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)
> 3.4
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
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)
> 0.019
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
Oncorhynchus mykiss
High
Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)
0.005
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
Cyprinus carpio
High
Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
> 1.99
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
Danio rerio
Moderate
Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)
> 0.021
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
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)
- - -
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)
- - -
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)
685
G4 G = Extension Toxicology network database EXTOXNET. Available online but no longer updated. (click here )
4 = Verified data
Rat
Moderate
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
2660
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rabbit
-
Mammals - Inhalation LC₅₀ (mg l⁻¹)
> 3.88
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
Low risk to Europeans as no longer approved for use
Occupational
Exposure may occur via skin contact or inhalation - PPE/PPC advised
Mammalian dose elimination route and rate
Urinary (25 - 50%) and faecal (50-70%) in around 3 days
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
?Possibly, status not identified
Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant
No data found
XNo, known not to cause a problem
No data found
Respiratory tract irritant Skin irritant Skin sensitiser
Yes, known to cause a problem
Yes, known to cause a problem
No data found
Eye irritant Phototoxicant  
Yes, known to cause a problem
No data found  
General human health issues
Moderately toxic
Potential mutagen
Kidney and liver toxicant
Inhalation may cause asthma, coughing, wheezing, running nose and eyes
Handling issues
Property
Value and interpretation
General
Incompatible with alkalis
Sensitive to light
CLP classification 2013
Health: H302, H332
Environment: H400, H410
WHO Classification
II (Moderately hazardous)
UN Number
-
Waste disposal & packaging
-
Shelf-life, storage, stability and reactivity
-
TRANSLATIONS
Language
Name
English
allethrin
French
allethrine
German
Allethrin
Danish
d-trans-allethrin
Italian
alletrina
Spanish
aletrina
Greek
allethrin bioallethrin
Polish
aletryna
Swedish
-
Hungarian
-
Dutch
allethrin
Norwegian
-

Record last updated: 24/08/2024
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