Propylene glycol

Propylene glycol	Last updated: 15/09/2025
(Also known as: methylethyl glycol; E1520)

GENERAL INFORMATION

Description

A synthetic food and feed additive

Examples of veterinary uses

Used for the treatment of acetonaemia and ketosis, to aid the delivery of skin healing medication as well as a general purpose feed additive

Examples of species treated

Dogs; Cattle; Sheep; Horses

Approval status

VMR 2013/2033 approval status (GB/UK)

Approved - authorisation legal class is variable and depends on product and application

EU Regulatory approval status

Approved

Chemical structure

Isomerism

None

Chemical formula

C₃H₈O₂

Canonical SMILES

CC(CO)O

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

DNIAPMSPPWPWGF-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C3H8O2/c1-3(5)2-4/h3-5H,2H2,1H3

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Feed additive

Other bioactivity & uses

Solvent; Humectant; Carrier

Substance groups

Unclassified substance

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Inert

Molecular targets

[No molecular target - physical mode of action]

CAS RN

57-55-6

EC number

200-338-0

CIPAC number

US EPA chemical code

068603

PubChem CID

Therapeutic Class

Alimentary tract & metabolism: Other alimentary tract & metabolism products

ATCvet Code

QA16QA01

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: All food producing species)

Molecular mass

76.09

PIN (Preferred Identification Name)

IUPAC name

propane-1,2-diol

CAS name

1,2-propanediol

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

Physical state

Colourless viscous liquid

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1942, GRAS status USA

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

Zoetis UK Ltd
Alfasan Nederland B.V.
Norbrook Laboratories Ltd

Example products using this active

Dermisol Cream
Forketos Oral Solution
Ketosaid Oral Solution

Formulation and application details

Available in a variety of formulations including creams and ointments, oral drenches and oral solutions

Commercial production

The production of propylene glycol primarily involves the hydration of propylene oxide, a compound derived from petroleum or natural gas. In this process, propylene oxide reacts with water, either under high temperature and pressure or in the presence of a catalyst, to yield a mixture of mono- and di-propylene glycol, with propylene glycol being the major product. Alternative methods include the chlorohydrin process and biobased synthesis from glycerol or lactic acid, offering more sustainable routes.

Impact on climate of production and use

The production of propylene glycol emits approximately 4.17 kilograms of CO₂e per kilogram of product. This figure reflects the climate footprint based on a benchmark industrial process and includes emissions from raw material sourcing, chemical processing, and energy use. The majority of the emissions stem from fossil resource inputs, about 77%, while the remaining 23% comes from processing energy.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

1000000

at 25 °C

High

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

Miscible

Ethanol

Miscible

Acetone

Miscible

Chloroform

Miscible

Ether

Melting point (°C)

-59

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

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

1.20 X 10^-01

Calculated

Log P

-0.92

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.036

Dissociation constant pKa) at 25 °C

14.9

Very weak acid

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)

Refractive Index

Environmental release

Degradation

Property

Value

Source; quality score; and other information

Interpretation

Soil degradation (days) (aerobic)

DT₅₀ (typical)

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

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

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)

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

Bio-concentration factor

BCF (l kg⁻¹)

CT₅₀ (days)

Known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 20000

Rat

Low

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)

2080

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)

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

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)

710

Pimephales promelas

Low

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)

10000

Daphnia magna

Low

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 (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)

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)

Low (class I)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 20000

Rat

Low

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

20800

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

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

Occupational

Mammalian dose elimination route and rate

Mainly eliminated unchanged in the urine

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

No data found

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

Possible liver and kidney toxicant
May cause seizures, coma, arrhythmias & cardiorespiratory arrest

Handling issues

Property

Value and interpretation

General

Flammable

CLP classification 2013

WHO Classification

Not listed (Not listed)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

propylene glycol

French

German

1,2-Propylenglykol

Danish

Italian

Spanish

Greek

Polish

propylenowo-glikolowy

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	15/09/2025
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