Indolylacetic acid

Indolylacetic acid	Last updated: 12/06/2024
(Also known as: IAA; AIA; beta-indoleacetic acid; auxins; heteroauxin; indole-3-ylacetic acid)

SUMMARY

A botanical extract that can be used as a plant growth regulator for use indoors but which does not have EU approval for use. It is highly soluble in water and volatile. Little is known about its environmental persistance but there are indications that it may be persistent under certain conditions in water. However, it is unstable in UV light. It is moderately toxic to mammals but generally not thought to present significant risk of causing problems for human health although there are uncertainties regarding its effect for reproduction and the CNS. Little is known regarding its ecotoxicology.

Data 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.

Environmental fate	Ecotoxicity	Human health
		Human health Moderate alert: Reproduction/development effects; Neurotoxicant

GENERAL INFORMATION

Description

A botanical auxin extract used to improve rootings of woody plant cuttings

Example pests controlled

Growth

Example applications

Ornamentals

Efficacy & activity

Appearance and life cycle

Availability status

Current

Introduction & key dates

circa 1940s, developed; 1946, first introduced

Taxonomic classification

GB regulatory status

GB COPR regulatory status

Not approved

Date COPR inclusion expires

Expired

GB LERAP status

No UK approval for use as a pesticide

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

Known to be also used in the following countries

USA, South Africa

Chemical structure

Isomerism

Chemical formula

C₁₀H₉NO₂

Canonical SMILES

C1=CC=C2C(=C1)C(=CN2)CC(=O)O

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

SEOVTRFCIGRIMH-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C10H9NO2/c12-10(13)6-8-5-7-3-1-2-4-9(7)11-8/h1-5,11H,6H2,(H,12,13)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
indolylacetic acid	-

General status

Biopesticide type

Plant Growth Regulator

Substance groups

Plant-derived substance; Micro-organism derived substance

Minimum active substance purity

990

Known relevant impurities

EU dossier - none declared

Substance origin

Natural

Mode of action

Broad spectrum, effects cell division and elongation stimulating the formation of roots.

Substance source

A plant auxin that is produced in cells of the buds and young leaves of plants, In addition, various microorganisms have shown the ability to produce IAA, such as bacteria, actinomycetes, fungi or yeast

Substance production

Produced via various techniques including chemical synthesis and microbial production

Uses

Yield enhancement

Target pests

None - PGR

Target host

Ornamentals

Farming system suitability

Suitable for use in all farming systems where approved for use in that country

CAS RN

87-51-4

EC number

201-748-2

CIPAC number

8186

US EPA chemical code

128915

PubChem CID

Molecular mass

175.18

PIN (Preferred Identification Name)

IUPAC name

1H-indole-3-acetic acid

CAS name

indol-3-ylacetic acid

Other status information

Relevant Environmental Water Quality Standards

Herbicide Resistance Class (HRAC MoA class)

Not applicable

Herbicide Resistance Class (WSSA MoA class)

Not applicable

Insecticide Resistance Class (IRAC MoA class)

Not applicable

Fungicide Resistance Class (FRAC MOA class)

Not applicable

Examples of recorded resistance

Physical state

Colourless to pale pink crystals

Related substances & organisms

1-naphthylacetic acid

Formulations

Property

Product

Manufacturer

Example products

Rhizopon AA

Hortus USA

1H-Indole-3-acetic acid, 99+%

Acros Organics BVBA

Formulation and application details

Often supplied as a dustable powder or as water soluble tablets

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

1500

High

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

1000000

Ethanol

65000

Diethyl ether

65000

Acetone

20000

Chloroform

Melting point (°C)

167

Boiling point (°C)

363

Degradation point (°C)

Flashpoint (°C)

171

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

2.57 X 10⁰¹

Calculated

Log P

1.41

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.576

Dissociation constant pKa) at 25 °C

4.75

Weak acid

Vapour pressure at 20 °C (mPa)

0.021

Low volatility

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

2.3 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

Neutral: max at 220nm, shoulders at 200nm, 280nm

Surface tension (mN m⁻¹)

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

DT₅₀ (lab at 20 °C)

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

General literature reports rapid degradation in soil

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

Note

Unstable in UV light

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

Value

Stable

Note

Water-sediment DT₅₀ (days)

Water 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

Known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 5000

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)

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

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

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)

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)

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 - Acute 7 day EC₅₀, biomass (mg l⁻¹)

Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)

> 1.69

Scenedesmus quadricauda

Moderate

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

Mesocosm study data

NOEAEC mg l⁻¹

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

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)

> 5000

Rat

Low

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 1.77

Rat

Other Mammal toxicity endpoints

Intraperitoneal LD₅₀ = 150 mg kg⁻¹

Mouse

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

Not allocated

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

Not allocated

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

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

0.055

Mouse SF=900

Dermal penetration studies (%)

11.3

Dangerous Substances Directive 76/464

Exposure Routes

Public

Not expected to pose a significant risk

Occupational

Not expected to pose a significant risk

Mammalian dose elimination route and rate

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

No data found

; ; ; ;

No data found

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

May cause respiratory problems

Handling issues

Property

Value and interpretation

General

Light sensitive
Not explosive or oxidising
Not expected to auto-ignite; Not highly flammable

CLP classification 2013

Health: H315, H319, H335

WHO Classification

Not listed (Not listed)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

Limited shelf life. Store at -20 DegC

TRANSLATIONS

Language

Name

English

indolylacetic acid

French

AIA

German

Danish

Italian

Spanish

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	12/06/2024
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