Pyrethrins (mix)

Pyrethrins (mix)	Last updated: 22/10/2025
(Also known as: pyrethum)

GENERAL INFORMATION

Description

A non-persistent insecticide extracted from pyrethrum used to control a variety of insect parasites

Examples of veterinary uses

Used as a topical treatment for fleas and ticks

Examples of species treated

Dogs; Cats; Horses

Approval status

VMR 2013/2033 approval status (GB/UK)

Approved - usually available as an authorised veterinary medicine for general sale (AVM-GSL)

EU Regulatory approval status

Approved

Chemical structure

Isomerism

The technical pyrethrins material is a mixture of pyrethrin-I & II, jasmolin I & II and cinerin I & II all of which are complex molecules with three chiral centres each.

Chemical formula

Canonical SMILES

Isomeric SMILES

International Chemical Identifier key (InChIKey)

International Chemical Identifier (InChI)

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

[Voltage-gated sodium channels, Agonist]

CAS RN

8003-34-7

EC number

CIPAC number

US EPA chemical code

PubChem CID

Therapeutic Class

Antiparasitic Products, Insecticides and Repellents: Ectoparasiticides, Insecticides and Repellents

ATCvet Code

QP53AC51

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: All food producing species)

Molecular mass

PIN (Preferred Identification Name)

IUPAC name

CAS name

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

Viscous amber coloured liquid

Related substances & organisms

pyrethrins (cinerin I)

pyrethrins (jasmolin I)

pyrethrins (pyrethrin I)

pyrethrins (cinerin II)

pyrethrins (jasmolin II)

pyrethrins (pyrethrin II)

Commercial

Property

Value

Availability status

Current

Introduction & key dates

Circa 1930, introduced

Example manufacturers & suppliers of products using this active now or historically

Solabiol
Sumitomo Chemical Co.
MGK
Diatect International
Agropharm Ltd
Sinclair Animal and Household Care Ltd
Johnson's Veterinary Products

Example products using this active

Insektkonsentrat P
PyGanic
Evergreen Crop Protection 60-6
Diatect II
Pyrethrum 5EC concentrate
Armitage Pet Care Insecticidal Shampoo
Beaphar Flea Shampoo

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.

Commercial production

Chrysanthemum cinerariifolium plants are cultivated and once blooming the flowers are harvested and dried. The dried flower heads are processed to extract the pyrethrins. This is typically done using a proprietary extraction method that maintains the natural composition of the pyrethrins. The crude extract contains a mixture of pyrethrins, including pyrethrin I, pyrethrin II, cinerins, and jasmolins.

Impact on climate of production and use

There are no precise, published data on the GHG emissions associated with the production of pyrethrins. However, based on similar plant-derived biopesticides, the estimated emissions would be expected to be around 3.0–6.5 kg CO₂e per kg of pyrethrins.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

Solubility - In water at 20 °C at pH 7 (mg l⁻¹)

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

Melting point (°C)

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

7.94 X 10⁰⁵

Calculated

Log P

5.9

High

Fat solubility of residues

Solubility

Soluble

Data type

Regulatory data

Density (g ml⁻¹)

0.85

Dissociation constant pKa) at 25 °C

No dissociation

Vapour pressure at 20 °C (mPa)

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

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)

52.8

Refractive Index

Environmental release

Degradation

Property

Value

Source; quality score; and other information

Interpretation

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Non-persistent

DT₅₀ (lab at 20 °C)

2.5

Non-persistent

DT₅₀ (field)

Non-persistent

DT₉₀ (lab at 20 °C)

6.3

Non-persistent

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

[Wheat grain: 55 wks @ 30 DegC, 50% RH; Modelled data]

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d (mL g⁻¹)

K_oc (mL g⁻¹)

Notes and range

Freundlich

K_f (mL g⁻¹)

Non-mobile

K_foc (mL g⁻¹)

27019

¹/_n

0.986

Notes and range

EU dossier data for pyrethrins K_f range 198-430 mL g⁻¹, kfoc range 12472-74175 mL g⁻¹, ¹/_n range 0.907-1.10, Soils=4

pH sensitivity

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

Whole fish

Threshold for concern

CT₅₀ (days)

Not available

Known soil and groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

dicarboxylic-chrysanthenic acid

Plant; Humans (Urine)

aldehyde-chrysanthenic acid

Plant

hydroxy-chrysanthenic acid

Plant

dihydroxy-chrysanthenic acid

Plant

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

700

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

(ppm diet)

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

300

Rat Reproductive NOAEL

Low

Birds - Acute LD₅₀ (mg kg⁻¹)

> 51151

Anas platyrhynchos

Low

Birds - Short term dietary (LC₅₀/LD₅₀)

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

Coturnix japonica NOEL

Moderate

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

23.7

Eisenia foetida corr

Moderate

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

0.25

Eisenia foetida corr

Moderate

Soil micro-organisms

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Non-target plants

Vegetative vigour ER₅₀ (g ha⁻¹)

> 39.9

10 plant species tested

Seedling emergence ER₅₀ (g ha⁻¹)

> 39.9

10 plant species tested

Honeybees (Apis spp.)

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

0.013

Apis mellifera

High

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

0.95

Apis mellifera

High

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

Chronic

Notes

[USEPA LD50 contact reported as 0.022 ug/bee, oral reported as 0.15 ug/bee]

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) as Mortality, LR₅₀, g ha⁻¹, Std lab test

> 12.2

Chrysoperla carnea

Moderate

Beneficial insects (Parasitic wasps) as Mortality LR₅₀ g ha⁻¹, Std lab test

59.4

Aphidius rhopalosiphi

Moderate

Beneficial insects (Predatory mites) as Mortality LR₅₀ g ha⁻¹, Std lab test

5.2

Typhlodromus pyri

Moderate

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)

0.005

Oncorhynchus mykiss

High

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

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

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

0.012

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)

0.0014

Americamysis bahia

High

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

Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l⁻¹)

0.01

Chironomus riparius

Moderate

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)

320

Unknown species

Low

Algae - Chronic (growth rate, fresh; mg l⁻¹)

Mesocosm study data

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)

700

Rat

Moderate

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

> 2000

Rat A4

Mammals - Inhalation LC₅₀ (mg l⁻¹)

3.4

Rat

Other Mammal toxicity endpoints

Intraperitoneal LD₅₀ = 200 mg kg⁻¹

Rat

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

0.04

Rat SF=100

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

0.2

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

Dermal penetration studies (%)

default

Dangerous Substances Directive 76/464

Exposure Routes

Public

Occupational

Mammalian dose elimination route and rate

Almost completely excreted within 72hrs

Health issues

Specific human health issues (hazard-based)

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

No data found

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

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 Hazard Class 9, Not expected to auto-ignite; Not highly flammable

CLP classification 2013

Health: H332, H312, H302
Environment: H400, H410

WHO Classification

II (Moderately hazardous)

UN Number

UN3082

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

pyrethrins (mix)

French

pyrethrines

German

Pyrethrine

Danish

pyrethrin

Italian

piretrine

Spanish

piretrina

Greek

Polish

pyretryny

Swedish

pyretriner

Hungarian

Dutch

pyrethrinen

Norwegian

pyretriner

Record last updated:	22/10/2025
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