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Pyrethrins (cinerin II)
Last updated: 27/10/2022
(Also known as: pyrethum; cinerin)

Data alerts

The following alerts are based on the data in the tables below. An absence of an alert does not imply the substance has no implications for human health, biodiversity or the environment but just that we do not have the data to form a judgement.

Environmental fate Ecotoxicity Human health
Environmental fate
Moderate alert:
Potential for particle bound transport: Medium
Ecotoxicity
High alert:
Fish acute ecotoxicity: High; Bees acute contact ecotoxicity: High; Bees acute oral ecotoxicity: High
Human health
Moderate alert:
Mammals acute toxicity: Moderate; Possible Endocrine distrupter; Possible Reproduction/development effects
GENERAL INFORMATION
Description
A non-persistent insecticide extracted from Pyrethrum used to control a variety of insect parasites
Availability status
Current
Introduction & key dates
circa 1930
Examples of species treated
Dogs, Cats, Horses
Chemical structure
Isomerism
Cinerin II is a complex molecule with three chiral centres.
Chemical formula
C₂₁H₂₈O₅
Canonical SMILES
CC=CCC1=C(C(CC1=O)OC(=O)C2C(C2(C)C)C=C(C)C(=O)OC)C
Isomeric SMILES
C/C=C\CC1=C([C@H](CC1=O)OC(=O)[C@@H]2[C@H](C2(C)C)/C=C(\C)/C(=O)OC)C
International Chemical Identifier key (InChIKey)
SHCRDCOTRILILT-WOBDGSLYSA-N
International Chemical Identifier (InChI)
InChI=1S/C21H28O5/c1-7-8-9-14-13(3)17(11-16(14)22)26-20(24)18-15(21(18,4)5)10-12(2)19(23)25-6/h7-8,10,15,17-18H,9,11H2,1-6H3/b8-7+,12-10+/t15-,17-,18+/m1/s1
2D structure diagram/image available?
Yes
General status
Veterinary substance type
Insecticide, Antiparasitic
Substance groups
Plant derived substance
Minimum active substance purity
-
Known relevant impurities
-
Substance origin
Natural
Mode of action
Contact acting neurotoxins with repellent properties. Sodium channel modulator.
Molecular targets
-
CAS RN
121-20-0
Alternative/old CAS RN
8003-34-7
EC number
204-454-2
CIPAC number
32
US EPA chemical code
-
PubChem CID
-
ATCvet Code
QP53AC51
Therapeutic Class
Antiparasitic Products, Insecticides and Repellents: Ectoparasiticides, Insecticides and Repellents
Controlled Drug?
No
Regulation 37/2010 MRL Classification
Allowable substance (Table 1: All food producing species)
Molecular mass
360.4
PIN (Preferred Identification Name)
-
IUPAC name
(Z)-(S)-3-(but-2-enyl)-2-methyl-4-oxocyclopent-2-enyl (E)-(1R)-trans-3-(2-methoxycarbonylprop-1-enyl)-2,2–dimethylcyclopropanecarboxylate
CAS name
(1R-(1α(S(Z),3β(E)))-3-(2-butenyl)-2-methyl-4-oxo-2-cyclopenten-1-yl 3-(3-methoxy-2-methyl-3-oxo-1-propenyl)-2,2-dimethylcyclopropanecarboxylate
Other status information
-
Relevant Environmental Water Quality Standards
-
Physical state
Viscous amber coloured liquid
Related substances & organisms
Formulations
Property
Product
Manufacturer
Authorisation Route
UK Legal Class
Example products using this active
Johnsons Dog Flea Shampoo Johnsons Veterinary Products UK National authorisation Authorised veterinary medicine for general sale (AVM - GSL)
Radiol Insecticidal Soapless Shampoo and Conditioner Battle, Hayward & Bower Ltd UK National authorisation (IC) Authorised veterinary medicine for general sale (AVM - GSL)
Armitage Pet Care Flea Spray for Cats Armitage Bros PLC UK National authorisation Authorised veterinary medicine for general sale (AVM - GSL)
Beaphar Ear Drops Solution Johnsons Veterinary Products UK National authorisation (IC) Authorised veterinary medicine for general sale (AVM - GSL)
Formulation and application details
Available in a variety of formulations including ultra low-volume liquids and ready-to-use sprays for crop and public health applications and as powders, shampoos and impregnated collars for animals.
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
0.30
V3 V = ChemID online databases / IPCS INCHEM (ChemID; IPCS INCHEM )
3 = Unverified data of known source
Low
Solubility - In organic solvents at 20 °C (mg l⁻¹)
250000
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
n-Heptane
-
250000
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
p-Xylene
-
250000
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
Methane
-
250000
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
Acetone
-
Melting point (°C)
- - -
Boiling point (°C)
- - -
Degradation point (°C)
180
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
-
Flashpoint (°C)
- - -
Octanol-water partition coefficient at pH 7, 20 °C
P
1.82 X 1004 Calculated -
Log P
4.26
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
High
Fat solubility of residues
Solubility
- - -
Data type
- - -
Density (g ml⁻¹)
0.85
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
-
Dissociation constant pKa) at 25 °C
Not applicable
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
-
No dissociation
Vapour pressure at 20 °C (mPa)
2.77 X 10-02
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
Low volatility
Henry's law constant at 25 °C (Pa m³ mol⁻¹)
- - -
Maximum UV-vis absorption L mol⁻¹ cm⁻¹
- - -
Surface tension (mN m⁻¹)
52.8
A4 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 )
4 = Verified data
as pyrethrins
-
Refractive Index
- - -
Degradation
Property
Value
Source; quality score; and other information
Interpretation
Soil degradation (days) (aerobic)
DT₅₀ (typical)
2
A4 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 )
4 = Verified data
Non-persistent
DT₅₀ (lab at 20 °C)
2.5
A4 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 )
4 = Verified data
Non-persistent
DT₅₀ (field)
12
H4 H = The US ARS pesticide properties database (click here )
4 = Verified data
Non-persistent
DT₉₀ (lab at 20 °C)
6.3
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
Non-persistent
DT₉₀ (field)
- - -
Note
EU dossier lab studies for pyrethrins
Manure DT₅₀ (days)
- - -
Aqueous photolysis DT₅₀ (days) at pH 7
Value
0.5
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
Fast
Note
Rapid
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7
Value
528
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
Very persistent
Note
-
Water-sediment DT₅₀ (days)
3.7
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
Fast
Water phase only DT₅₀ (days)
1.0
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
Moderately fast
Soil adsorption and mobility
Property
Value
Source; quality score; and other information
Interpretation
Linear
Kd
-
H3 H = The US ARS pesticide properties database (click here )
3 = Unverified data of known source
Non-mobile
Koc
100000
Notes and range
Literature data
Freundlich
Kf
298
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
Non-mobile
Kfoc
27019
1/n
0.986
Notes and range
EU dossier data for pyrethrins Kf range 198-430 mL g⁻¹, kfoc range 12472-74175 mL g⁻¹, 1/n range 0.907-1.10, soils=4
pH sensitivity
No
Fate indices
Property
Value
Source; quality score; and other information
Interpretation
GUS leaching potential index
-0.47 Calculated Low leachability
Bio-concentration factor
BCF (l kg⁻¹)
471
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
Whole body
Threshold for concern
CT₅₀ (days)
Not available -
Known soil metabolites
Metabolite
Major/Minor fraction
Estimated maximum occurrence fraction
Notes
chrysanthemic acid
Minor fraction 0.05 -
Known groundwater metabolites

None

Other known metabolites
Metabolite name and reference
Aliases
Formation medium / Rate
Estimated maximum occurrence fraction
Metabolising enzymes
hydroxy-chrysanthenic acid - Plant - -
dihydroxy-chrysanthenic acid - Plant - -
dicarboxylic-chrysanthenic acid - Plant; Humans (Urine) - -
aldehyde-chrysanthenic acid - Plant - -
ECOTOXICOLOGY
Terrestrial ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
700
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
Rat as pyrethrins
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)
> 51151
A4 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 )
4 = Verified data
Anas platyrhynchos as pyrethrins
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)
23.7
A4 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 )
4 = Verified data
Eisenia foetida corr
Moderate
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)
0.25
A4 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 )
4 = Verified data
Eisenia foetida corr
Moderate
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)
0.33
K3 K = Research datasets, e.g. Pandora, Demetra
3 = Unverified data of known source
Apis mellifera
High
Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
K3 Apis mellifera 0.022 - High
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 pollinators (1)
Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)
- - -
Mode of exposure
-
Other pollinators (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)
Harmful
Q2 Q = Miscellaneous internet resources
2 = Unverified data of unknown source
Parasitic wasp
-
Beneficial insects (Predatory mites)
Harmless
AA2 AA = IOBC Database on classification of side effects to beneficial organisms, 2005
2 = Unverified data of unknown source
Typhlodromus pyri
-
Beneficial insects (Ground beetles)
- - -
Aquatic ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
0.005
A4 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 )
4 = Verified data
Oncorhynchus mykiss as pyrethrins
High
Fish - Chronic 21 day NOEC (mg l⁻¹)
- - -
Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)
0.359
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
Daphnia magna
Moderate
Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)
- - -
Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)
0.0014
A4 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 )
4 = Verified data
Americamysis bahia as pyrethrins
High
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)
320
S1 S = Expert judgement
1 = Estimated data with little or no verification
Unknown species
Low
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)
Intermediate (class II) - -
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
700
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
Rat as pyrethrins
Moderate
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
2000
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
Rat as pyrethrins
-
Mammals - Inhalation LC₅₀ (mg l⁻¹)
3.4
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
Rat (as pyrethrins)
-
Other Mammal toxicity endpoints
Intraperitoneal LD₅₀ = 200 mg kg⁻¹
V3 V = ChemID online databases / IPCS INCHEM (ChemID; IPCS INCHEM )
3 = Unverified data of known source
Rat as pyrethrins
-
ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)
0.04
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
Rat SF=100
-
ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)
0.2
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
Rat SF=100
-
AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)
- - -
AOEL - Acceptable Operator Exposure Level - Systemic (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
-
Dermal penetration studies (%)
10
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
default
-
Dangerous Substances Directive 76/464
- - -
Exposure Routes
Public
-
Occupational
-
Mammalian dose elimination route and rate
Almost completely excreted within 72hrs
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
-
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
?Possibly, status not identified
Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant
?Possibly, status not identified
XNo, known not to cause a problem
No data found
Respiratory tract irritant Skin irritant Skin sensitiser
?Possibly, status not identified
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
May cause dermatitis
May cause gastointestinal problems
Possible thyroid and liver toxicant
Handling issues
Property
Value and interpretation
General
Not explosive or oxidising
IMDG Transport Code is usually 9
Not expected to autoignite; Not highly flammable
CLP classification 2013
Health: H332, H312, H302
Environment: H400, H410
WHO Classification
II (Moderately hazardous)
UN Number
Usually 3082
Waste disposal & packaging
Packaging Group III (minor danger)
TRANSLATIONS
Language
Name
English
pyrethrins (cinerin II)
French
pyrethrines
German
Pyrethrine
Danish
pyrethrin
Italian
piretrine
Spanish
piretrina
Greek
-
Polish
pyretryny
Swedish
pyretriner
Hungarian
-
Dutch
pyrethrinen

Record last updated: 27/10/2022
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