Piperonyl butoxide (Ref: ENT 14250)

Piperonyl butoxide (Ref: ENT 14250)	Last updated: 04/09/2025
(Also known as: PBO; butacide; butoxide)

GENERAL INFORMATION

Description

An unclassified synergist used in a wide variety of insecticides to provide enhanced performance of the active ingredient

Examples of veterinary uses

Typically used in products for lice, flea and fliy infestations

Examples of species treated

Cats; Dogs; Horses; Pigeons; Caged birds

Approval status

VMR 2013/2033 approval status (GB/UK)

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

EU Regulatory approval status

Approved

Chemical structure

Isomerism

None

Chemical formula

C₁₉H₃₀O₅

Canonical SMILES

CCCCOCCOCCOCC1=CC2=C(C=C1CCC)OCO2

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

FIPWRIJSWJWJAI-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C19H30O5/c1-3-5-7-20-8-9-21-10-11-22-14-17-13-19-18(23-15-24-19)12-16(17)6-4-2/h12-13H,3-11,14-15H2,1-2H3

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Product performance enhancer

Other bioactivity & uses

Synergist

Substance groups

Cyclic aromatic substance; Synergist

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Blocks pests natural detoxification system. Synergist. P450-dependent monooxygenase inhibitor.

Molecular targets

[Cytochrome P-450, Inhibitor]

CAS RN

51-03-6

EC number

200-076-7

CIPAC number

US EPA chemical code

067501

PubChem CID

Therapeutic Class

Sensory organs: Otological substances

ATCvet Code

QS02QA

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: Bovine, Ovine, Caprine, Equidae)

Molecular mass

338.44

PIN (Preferred Identification Name)

IUPAC name

5-[2-(2-butoxyethoxy)ethoxymethyl]-6-propyl-1,3-benzodioxole

CAS name

5-((2-(2-butoxyethoxy)ethoxy)methyl)-6-propyl-1,3-benzodioxole

Forever chemical

Other status information

Listed on USA Toxic Release Inventory; Some applications may be approved under GB Biocides Products Regulations

Relevant Environmental Water Quality Standards

Physical state

Colourless to yellow oily liquid

Related substances & organisms

piperonyl sulfoxide

piperonyl cyclonene

Commercial

Property

Product

Manufacturer

Authorisation Route

Legal Class (GB/UK)

Availability status

Current

Introduction & key dates

circa 1950, introduced

Example products (past and present) using this active

Beaphar Cat Flea Spray

Sinclair Animal & Household Care Ltd

UK National authorisation

Authorised veterinary medicine for general sale (AVM-GSL)

Beaphar Ear Drops Solution

Sinclair Animal & Household Care Ltd

UK National authorisation

Authorised veterinary medicine for general sale (AVM-GSL)

Johnson's Anti Pest Insect Spray

Johnsons Veterinary Products Ltd

UK National authorisation

Authorised veterinary medicine for general sale (AVM-GSL)

Pets with Wilko Insectidal Shampoo

Sinclair Animal and Household Care Ltd

UK National authorisation

Authorised veterinary medicine for general sale (AVM-GSL)

Formulation and application details

Formulated for topical application such as cutaneous sprays, shampoos and powders

Commercial production

Piperonyl butoxide is synthesised through a multi-step chemical process that typically begins with safrole, a natural compound extracted from sassafras oil. The safrole undergoes catalytic hydrogenation to form dihydrosafrole, which is then subjected to chloromethylation using hydrochloric acid and polyformaldehyde to produce chloromethyl-dihydrosafrole. This intermediate is then reacted in a Williamson etherification with butyl alcohol derivatives under basic conditions to form the final ether structure of piperonyl butoxide.

Impact on climate of production and use

Data for the amount of life cycle GHGs produced by piperonyl butoxide are not available in the public domain. However, whilst estimates vary, more general data suggests that between 14 and 30 kilograms of CO₂e is emitted per kilogram of pesticide produced.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

14.3

Moderate

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

Melting point (°C)

Not applicable

Boiling point (°C)

Degradation point (°C)

164

Flashpoint (°C)

179

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

5.62 X 10⁰⁴

Calculated

Log P

4.75

High

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.06

Dissociation constant pKa) at 25 °C

Vapour pressure at 20 °C (mPa)

2.00 X 10^-02

Low volatility

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

2.30 X 10^-06

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)

50.39

Refractive Index

1.497-1.507

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)

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

Note

Best available data

Manure DT₅₀ (days)

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Note

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

Value

250

Persistent

Note

Stable pH 5 to pH 9 at 25 °C

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

K_d (mL g⁻¹)

Non-mobile

K_oc (mL g⁻¹)

89125

Notes and range

Other data: K_oc range 399-830 mL g⁻¹ (L3)

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

-1.06

Calculated

Low leachability

Bio-concentration factor

BCF (l kg⁻¹)

260

Lepomis macrochinis

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)

> 7220

Rat

Low

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat 2 yr

High

(ppm diet)

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

Birds - Acute LD₅₀ (mg kg⁻¹)

> 2250

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)

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

Soil micro-organisms

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Non-target plants

Vegetative vigour ER₅₀ (g ha⁻¹)

Seedling emergence ER₅₀ (g ha⁻¹)

Honeybees (Apis spp.)

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

294

Apis mellifera

Low

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) as Mortality LC₅₀ mg l⁻¹

> 1644

Coccinella septempunctata Adult

Beneficial insects (Lacewings) as Mortality, Contact LD₅₀ g l⁻¹

> 1.71

Chrysoperla carnea Larva

Moderate

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)

5.3

Cyprinidae spp.

Moderate

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

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

3.84

Danio rerio Embryo

Moderate

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

0.51

Daphnia magna

Moderate

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

0.12

Daphnia magna LOEC

Moderate

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, 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)

0.24

Unknown species

Moderate

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)

High (class III)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 7220

Rat

Low

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

1880

Rabbit

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 5.9

Rat

Other Mammal toxicity endpoints

Intraperitoneal LDLo = 1000 mg kg⁻¹

Mouse

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

0.2

JMPR 1995

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

None allocated

JMPR 2002

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

Majority of dose eliminated in faeces

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

No data found

General human health issues

Possible liver toxicant
IARC Group 3 carcinogen - not classifiable; US EPA - possible human carcinogen; Some sources dispute carcinogenicity

Handling issues

Property

Value and interpretation

General

Not explosive
IMDG Transport Hazard Class 9

CLP classification 2013

Health: H330, H361
Environment: H400, H410

WHO Classification

U (Unlikely to present an acute hazard)

UN Number

UN3082

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

piperonyl butoxide

French

pipéronyl butoxyde

German

Piperonylbutoxid

Danish

piperonylbutoxyd

Italian

piperonil butossido

Spanish

butoxido de piperonilo

Greek

Polish

piperonyl butoksydu

Swedish

piperonylbutoxid

Hungarian

Dutch

Norwegian

Record last updated:	04/09/2025
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