Ioxynil-octanoate

Ioxynil-octanoate	Last updated: 30/10/2025
(Not known by any other names)

SUMMARY

Hazard 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. These hazard alerts do not take account of usage patterns or exposure, thus do not represent risk.

Environmental fate	Ecotoxicity	Human health
Environmental fate Moderate alert: Drainflow: Moderately mobile; Potential for particle bound transport: Medium	Ecotoxicity High alert: Fish acute ecotoxicity: High; Daphnia acute ecotoxicity: High	Human health High alert: Endocrine disruptor

GENERAL INFORMATION

Description

A herbicide used for post-emergence control of various broadleaved weeds

Example pests controlled

Annual broadleaved weeds

Example applications

Cereals; Onions; Leeks; Garlic; Shallots; Flax; Sugarcane; Forage grasses; Lawns & turf

Efficacy & activity

GB regulatory status

GB COPR regulatory status

Not approved

Date COPR inclusion expires

Expired

GB LERAP status

No UK approval for use as a plant protection agent

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Not approved

Dossier rapporteur/co-rapporteur

France

Date EC 1107/2009 inclusion expires

Expired

EU Candidate for substitution (CfS)

Not applicable

Listed in EU database

Yes

Approved for use (✓) under EC 1107/2009 in the following EU Member States

ATAustria	BEBelgium	BGBulgaria	CYCyprus	CZCzech Republic	DEGermany	DKDenmark	EEEstonia	ELGreece

ESSpain	FIFinland	FRFrance	HRCroatia	HUHungary	IEIreland	ITItaly	LTLithuania	LULuxembourg

LVLatvia	MTMalta	NLNetherlands	PLPoland	PTPortugal	RORomania	SESweden	SISlovenia	SKSlovakia

Approved for use (✓) under EC 1107/2009 by Mutual Recognition of Authorisation and/or national regulations in the following EEA countries

ISIceland	NONorway

Additional information

Also used in

Australia

Chemical structure

Isomerism

None

Chemical formula

C₁₅H₁₇I₂NO₂

Canonical SMILES

CCCCCCCC(=O)OC1=C(C=C(C=C1I)C#N)I

Isomeric SMILES

International Chemical Identifier key (InChIKey)

QBEXFUOWUYCXNI-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C15H17I2NO2/c1-2-3-4-5-6-7-14(19)20-15-12(16)8-11(10-18)9-13(15)17/h8-9H,2-7H2,1H3

2D structure diagram/image available?

Yes

General status

Pesticide type

Herbicide

Substance groups

Nitrile herbicide

Minimum active substance purity

920 g kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

Selective, systemic with contact action. Photosynthetic electron transport inhibitor at the photosystem II.

CAS RN

3861-47-0

EC number

223-375-4

CIPAC number

US EPA chemical code

PubChem CID

19730

CLP index number

608-018-00-6

Molecular mass

497.1

PIN (Preferred Identification Name)

4-cyano-2,6-diiodophenyl octanoate

IUPAC name

4-cyano-2,6-diiodophenyl octanoate

CAS name

4-cyano-2,6-diiodophenyl octanoate

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

Highly Hazardous Pesticide (HHP)

Type I

Type II

Yes [; ]

Other status information

Marine pollutant

Herbicide Resistance Class (HRAC MoA class)

Herbicide Resistance Class (WSSA MoA class)

Insecticide Resistance Class (IRAC MoA class)

Not applicable

Fungicide Resistance Class (FRAC MOA class)

Not applicable

Examples of recorded resistance

Physical state

Fine white powder

Related substances & organisms

ioxynil

ioxynil-lithium

ioxynil-sodium

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1963, ioxynil patented; 1966, ioxynil introduced commercially

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

Bayer CropScience
Makhteshim-Agan
NuFarm

Example products using this active

Briotril
Oxytril
Stellox
Actril
Totril.

Formulation and application details

Often supplied as a emulsifiable concentrate that is mixed with water and used as a spray

Commercial production

Ioxynil-octanoate is commercially synthesised by esterifying ioxynil with octanoic acid. The production process begins with the preparation of the ioxynil intermediate, which involves iodination of 4-hydroxybenzonitrile to introduce the diiodo substituents. This compound is then reacted with octanoic acid or its acid chloride in the presence of a catalyst, typically a base or acid catalyst, to form the octanoate ester. The esterification is conducted under controlled temperature and solvent conditions to ensure high yield and purity.

Impact on climate of production and use

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

0.03

Low

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

1000000

Acetone

1000000

Ethyl acetate

111800

Methanol

1000000

Xylene

Melting point (°C)

56.6

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

240

Flashpoint (°C)

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

1.00 X 10⁰⁶

Calculated

Log P

6.0

High

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.81

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

0.9 X 10^-04

at 45 °C

Low volatility

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

227nm = 29738, 295nm = 1099

Surface tension (mN m⁻¹)

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Non-persistent

DT₅₀ (lab at 20 °C)

Non-persistent

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

EU dossier lab studies DT₅₀ range 3-10days

Dissipation rate RL₅₀ (days) on plant matrix

Value

Note

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

Note

Aqueous photolysis DT₅₀ (days) at pH 7

Value

6.9

Moderately fast

Note

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

Value

Non-persistent

Note

pH and temperature sensitive: stable at pH 4 and pH 5 both at 22-25 °C, DT₅₀ 6 days at pH 7 and 22 °C, 52 days at pH 7 and 25 °C, 16 days at pH 9 and 22 °C, 5.3 days pH 9 and 25 °C

Water-sediment DT₅₀ (days)

3.3

Fast

Water phase only DT₅₀ (days)

0.67

Fast

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)

3.94

Moderately mobile

K_foc (mL g⁻¹)

289

¹/_n

0.81

Notes and range

EU dossier K_f range 0.66-9.44 mL g⁻¹, K_foc range 64-786 mL g⁻¹, ¹/_n range 0.52-0.91

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.30

Calculated

Low leachability

SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate

Value

9.79 X 10^-03

Calculated

Note

Potential for particle bound transport index

Medium

Calculated

Potential for loss via drain flow

Moderately mobile

Calculated

Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk

7.2

Calculated using the Atkinson method. EU trigger for long-range transport is DT₅₀ in air <2 days.

Below the level of concern for long-range air transport

Bio-concentration factor

BCF (l kg⁻¹)

188

Whole fish

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

ioxynil (Ref: ACP 63-303)

Major fraction

0.526

3,5-di-iodo-4-hydroxybenzamide

Major fraction

3,5-di-iodo-4-hydroxybenzoic acid

Major fraction

Known groundwater metabolites

None

Other known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

165

Rat

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)

677

Coturnix japonica

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

2563 mg kg feed⁻¹

Coturnix japonica

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

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

> 60

Moderate

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

Soil micro-organisms

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

Dose: 2.94 mg ioxynil octanoate/kg soil

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)

> 200

Apis mellifera

Low

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

> 3.27

Apis mellifera

Moderate

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)

55.6% Mortality at dose 0.625 kg oxynil ha⁻¹

Aphidius rhopalosiphi Adult

Beneficial insects (Predatory mites)

98.7% Mortality at dose 0.625 kg oxynil ha⁻¹

Typhlodromus pyri Protonymph

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)

0.043

Unknown species

High

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

0.021

Unknown species

Moderate

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

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

0.011

Daphnia magna

High

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

0.010

Daphnia magna

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)

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) (EC₅₀)

0.017

Lemna gibba 14 day

Moderate

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)

High (class III)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

165

Rat

Moderate

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

> 2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

4.36

Rat

Other Mammal toxicity endpoints

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

0.005

Rat SF=100

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

0.04

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)

0.01

Rat SF=100

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

Exposure Routes

Public

Occupational

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

Mammalian dose elimination route and rate

Health issues

Specific human health issues (hazard-based)

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 thyroid toxicant

Handling issues

Property

Value and interpretation

General

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

CLP classification 2013

Health: H301, H317, H319
Environment: H410

WHO Classification

II (Moderately hazardous)

UN Number

UN3077

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

Sability may be affected by light

TRANSLATIONS

Language

Name

English

ioxynil-octanoate

French

German

Danish

Italian

Spanish

Greek

Polish

Swedish

ioxinil oktansyraester

Hungarian

Dutch

Norwegian

Record last updated:	30/10/2025
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