Cypermethrin (Ref: OMS 2002)

Cypermethrin (Ref: OMS 2002)	Last updated: 14/11/2024
(Also known as: cypermethrine)

SUMMARY

Cypermethrin is a broad-spectrum insecticide. It has a low aqueous solubility and is volatile. Whilst its chemical properties suggest that it should not leach to groundwater it has been detected. It is considered a serious marine pollutant. It is moderately persistent is soils but is likely to degrade moderately fast in water systems under daylight conditions. It is moderately toxic to mammals and there is some concern regarding its potential to bioaccumulate. Whilst it is an irritant, no serious human health issues have been identified. It is highly toxic to most aquatic species and honeybees. It is moderately toxic to earthworms but there is little risk to birds.

GENERAL INFORMATION

Description

An insecticide used to control ectoparasitic infestations

Availability status

Current

Introduction & key dates

1975, first reported

Examples of veterinary uses

Used to control ticks, mites, lice & fleas

Examples of species treated

Horses; Cattle; Sheep; Salmon; Camels

Approval status

VMR 2013/2033 approval status (GB/UK)

Approved

EU Regulatory approval status

Approved

Chemical structure

Isomerism

Cypermethrin is a chiral molecule. The technical material consists of eight isomers, four cis and four trans.

Chemical formula

C₂₂H₁₉Cl₂NO₃

Canonical SMILES

CC1(C(C1C(=O)OC(C#N)C2=CC(=CC=C2)OC3=CC=CC=C3)C=C(Cl)Cl)C

Isomeric SMILES

International Chemical Identifier key (InChIKey)

KAATUXNTWXVJKI-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C22H19Cl2NO3/c1-22(2)17(12-19(23)24)20(22)21(26)28-18(13-25)14-7-6-10-16(11-14)27-15-8-4-3-5-9-15/h3-12,17-18,20H,1-2H3

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
cypermethrin	Isomer
alpha-cypermethrin	Isomer

General status

Veterinary substance type

Insecticide, Sheep dip

Other bioactivity & uses

Biocide, Wood preservative

Substance groups

Pyrethroid Insecticide; Pyrethroid acaricide; Pyrethroid ester insecticide; Pyrethroid ester acaricide

Minimum active substance purity

920 g kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

Non-systemic with contact and stomach action. Sodium channel modulator.

Molecular targets

[Sodium channel, Modulator]

CAS RN

52315-07-8

EC number

257-842-9

CIPAC number

332

US EPA chemical code

109702/129064

PubChem CID

2912

CLP index number

607-421-00-4

Therapeutic Class

Antiparasitic products, insecticides & repellents: Ecoparasiticides, insecticides & repellents

ATCvet Code

QP53AC08

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: Ruminants, Salmonidae)

Molecular mass

416.3

PIN (Preferred Identification Name)

(E)-cyano(3-phenoxyphenyl)methyl (1E,3E)-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carboxylate

IUPAC name

(RS)-α-cyano-3-phenoxybenzyl (1RS,3RS;1RS,3SR)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate

CAS name

cyano(3-phenoxyphenyl)methyl 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate

Other status information

Severe Marine Pollutant; Surface and Groundwater Pollutant; Some applications are approved under GB Biocides Products Regulations

Relevant Environmental Water Quality Standards

UK Environment Agency non-statutory standard for the protection of aquatic life in freshwater and saltwater annual average 0.0002 µg l⁻¹, max acceptable conc 0.002 µg l⁻¹
UK statutory standard for water quality: ‘Good’ for fresh, transitional & saltwater: 0.1 ng l⁻¹ as annual mean conc, 0.4 ng l⁻¹ 95th percentile

Physical state

Pale yellow liquid

Related substances & organisms

alpha-cypermethrin

beta-cypermethrin

zeta-cypermethrin

theta-cypermethrin

Formulations

Property

Product

Manufacturer

Authorisation Route

Legal Class (GB/UK)

Example products (past and present) using this active

Crovect Pour-on Solution

Elanco Europe Ltd

UK National authorisation (IC)

Prescription only medicine to be authorised by suitably qualified person (POM-VPS)

Ectofly Pour-on Solution

Bimeda Animal Health Ltd

GB National authorisation

Prescription only medicine to be authorised by suitably qualified person (POM-VPS)

Flectron Fly Ear Tags

Zoetis UK Ltd

UK National authorisation

Prescription only medicine to be authorised by suitably qualified person (POM-VPS)

Vectocert Pour-on

Bimeda Animal Health Ltd

UK National authorisation

Prescription only medicine to be authorised by suitably qualified person (POM-VPS)

Formulation and application details

Formulated for topical use such as sprays and pour-ons as well as medicated ear-tags

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

Solubility - In water at 20 °C (mg l⁻¹)

0.009

Low

Solubility - In organic solvents at 20 °C (mg l⁻¹)

2500000

Ethyl acetate

450000

Acetone

450000

Methanol

142000

Hexane

Melting point (°C)

41.2

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

220

Flashpoint (°C)

Octanol-water partition coefficient at pH 7, 20 °C

3.55 X 10⁰⁵

Calculated

Log P

5.55

High

Fat solubility of residues

Solubility

Soluble

Data type

Regulatory data - based on observations during animal metabolism and feeding studies

Density (g ml⁻¹)

1.3

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

6.78 X 10^-03

Low volatility

Henry's law constant at 25 °C (Pa m³ mol⁻¹)

0.31

Moderately volatile

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

Maximum UV-vis absorption L mol⁻¹ cm⁻¹

204nm = 43217, 278nm = 2368

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)

22.1

Non-persistent

DT₅₀ (lab at 20 °C)

22.1

Non-persistent

DT₅₀ (field)

21.9

Non-persistent

DT₉₀ (lab at 20 °C)

117.7

Persistent

DT₉₀ (field)

72.6

Note

EU 2017 dossier lab studies DT₅₀ range 2.4-58.3 days, DT₉₀ range 23.3-412 days, Soils=9, Field studies DT₅₀ range 9.3-31.2 days, DT₉₀ range 30.9-103.6 days, Soils=4; EU 2005 dossier Lab studies DT₅₀ (1) cis-isomer 31-107 days (2) trans-isomer 13-58 days, DT₉₀ (1) cis-isomer 102-792 days (2) trans-isomer 69-251 days; field studies DT₅₀ range 14-199 days, DT₉₀ range 28-375 days

Manure DT₅₀ (days)

Aqueous photolysis DT₅₀ (days) at pH 7

Value

7.8

Moderately fast

Note

Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7

Value

Stable

Note

Stable pH 3-7. Also varies with isomer: DT₅₀ 21.2 days pH 8 cis-isomer, 9.1 days pH 8 trans-isomer, ~30 mins at pH 11.

Water-sediment DT₅₀ (days)

Fast

Water phase only DT₅₀ (days)

Moderately fast

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

K_d (mL g⁻¹)

5435

Non-mobile

K_oc (mL g⁻¹)

307558

Notes and range

EU 2017 dossier K_d range 3871-8976 mL g⁻¹, K_oc range 80653-574360 mL g⁻¹, Soils=5

Freundlich

K_f (mL g⁻¹)

K_foc (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

-1.99

Calculated

Low leachability

Bio-concentration factor

BCF (l kg⁻¹)

331

Threshold for concern

CT₅₀ (days)

Not available

Known soil metabolites

Metabolite

Major/Minor fraction

$Click here for further information on Major/Minor fraction$

Estimated maximum occurrence fraction

Notes

3-phenoxybenzoic acid

Minor fraction

3-phenoxybenzoic acid

Major fraction

0.102

3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid

Major fraction

0.474

3-(4-hydroxyphenoxy)benzoic acid

Minor fraction

4-hydroxycypermethrin

Minor fraction

3-(2,2-dichloroethenyl(-2,2-dimethyl cyclopropane carboxylic acid (cis- and trans-)

Minor fraction

(RS)-Carbamoyl(3-phenoxyphenyl)-methyl (1RS)-cis,trans-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate

Minor fraction

3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid

Minor fraction

Photolysis

Known groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

4-hydroxycypermethrin

Animal

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

287

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

7.5

Rat 2 yr

High

(ppm diet)

Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)

7.5

Unknown species Reproductive NOAEL

High

Birds - Acute LD₅₀ (mg kg⁻¹)

> 9520

Anas platyrhynchos

Low

Birds - Short term dietary (LC₅₀/LD₅₀)

> 5620 mg kg feed⁻¹

Anas platyrhynchos

Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)

4.29

Colinus virginianus NOEL

High

Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)

> 100

Eisenia foetida

Moderate

Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)

> 5.3

Eisenia foetida corr

Moderate

Soil micro-organisms

Nitrogen mineralisation: No significant adverse effect
Carbon mineralisation: No significant adverse effect

Dose: 0.15 kg ha⁻¹; 28 Day

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

5.2

Folsomia candida corr

Non-target plants

> 150

Onion Oats Beet Soybean Sunflower
Vegetative vigour, ER₅₀
as g ha⁻¹

Honeybees (Apis spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

0.023

Apis mellifera

High

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

0.172

Apis mellifera

High

Unknown mode acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Chronic as 10-day LDD₅₀ µg bee⁻¹ day⁻¹

> 0.0149

Apis mellifera

Bumblebees (Bombus spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

0.119

Bombus terrestris

High

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

0.263

Bombus terrestris

High

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)

0.07

Trigona spinipes

High

Mode of exposure

Contact

Other bee species (2)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Beneficial insects (Ladybirds) as Mortality, Contact LC₅₀ ppm

> 20.4

Chrysoperla carnea Larva

Beneficial insects (Lacewings)

Beneficial insects (Parasitic wasps) as Mortality LR₅₀ g ha⁻¹

0.822

Aphidius rhopalosiphi

Beneficial insects (Predatory mites) as Mortality LR₅₀ g ha⁻¹

0.0029

Typhlodromus pyri

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)

0.00151

Oncorhynchus mykiss

High

Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)

0.00003

Pimephales promelas 34 day

High

Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

> 0.025

Danio rario Embryo

High

Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

0.00021

Daphnia magna

High

Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)

0.00004

Daphnia magna

High

Tropical Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

0.0004

Ceriodaphnia dubia

High

Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)

0.0128

Americamysis bahia

High

Sediment dwelling organisms - Acute 96 hour LC₅₀ (mg l⁻¹)

> 0.0018

Chironomus decorus 24 hr

High

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)

> 0.0667

Pseudokirchneriella subcapitata

Moderate

Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)

1.3

Unknown species

Low

Mesocosm study data

NOEAEC mg l⁻¹

0.00005

Aquatic invertebrates and algae

NOEAEC mg l⁻¹

Marine bivalves – Acute EC₅₀ development (mg l⁻¹)

> 2.27

Crassostrea gigas Embryo

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)

287

Rat

Moderate

Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

3.56

Rat

Other Mammal toxicity endpoints

Intraperitoneal LD₅₀ = 404 mg kg⁻¹

Rat

Intravenous LDLo = 6.0 mg kg⁻¹

Rat

ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)

0.005

ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)

0.005

AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)

0.0025

AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)

0.0025

Dermal penetration studies (%)

0.8-5

concentration dependent

Dangerous Substances Directive 76/464

Exposure Routes

Public

Negligible risks for bystanders and residents

Occupational

No unacceptable risks identified when following product label for poposed uses and using PPE/PPC

Mammalian dose elimination route and rate

Metabolised by the liver, urine is the principal route of elimination, faecal route less so, skin and pulmonary routes are not significant

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

Eye irritant

Phototoxicant

General human health issues

Highly toxic
US EPA - possible human carcinogen
Endocrine issues - Estrogenic effect
Possible liver & kidney toxicant

Handling issues

Property

Value and interpretation

General

Not explosive or oxidising
IMDG Transport Hazard Class 9
Not expected to auto-ignite; Not highly flammable

CLP classification 2013

Health: H301; H335. H373
Environment: H400, H410

WHO Classification

II (Moderately hazardous)

UN Number

UN3077

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

cypermethrin

French

cypermethrine

German

Cypermethrin

Danish

cypermethrin

Italian

cipermetrina

Spanish

cipermetrin

Greek

Polish

cypermetryna

Swedish

cypermetrin

Hungarian

cypermethrin

Dutch

cypermetrine

Norwegian

Record last updated:	14/11/2024
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