| Indolylacetic acid |
![]() Last updated: 28/11/2025 |
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(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. |
| Hazard alerts |
The following Pesticide Hazard Tricolour (PHT) 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. The alerts for Highly Hazardous Pesticides (HHPs) are based on applying the FAO/WHO (Type 1) and the PAN (Type II) criteria to PPDB data. Further details on the HHP indicators are given in the tables below. Neither the PHT nor the HHP hazard alerts take account of usage patterns or exposure, thus they do not represent risk.
| PHT: Environmental fate | PHT: Ecotoxicity | PHT: Human health | Highly Hazardous Pesticide |
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|   |   | Warning:Significant data are missing |
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A botanical auxin extract used to improve rootings of woody plant cuttings | |
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Growth | |
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Ornamentals | |
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| GB regulatory status |
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Not approved | ||
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Expired | ||
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No UK approval for use as a plant protection agent |
| EC Regulation 1107/2009 (repealing 91/414) |
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Not approved | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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France | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Expired | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Not applicable | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Yes | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Additional information |
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USA; South Africa |
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| Chemical structure |
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None | |
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C₁₀H₉NO₂ | |
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C1=CC=C2C(=C1)C(=CN2)CC(=O)O | |
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No data | |
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SEOVTRFCIGRIMH-UHFFFAOYSA-N | |
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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) | |
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Yes |
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| Common Name | Relationship | Link |
|---|---|---|
| indolylacetic acid | - | ![]() |
| General status |
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Plant Growth Regulator | ||||||||||||||
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Plant-derived substance; Micro-organism derived substance | ||||||||||||||
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990 g kg⁻¹ | ||||||||||||||
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EU dossier - none declared | ||||||||||||||
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Natural | ||||||||||||||
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Broad-spectrum, effects cell division and elongation stimulating the formation of roots. | ||||||||||||||
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87-51-4 | ||||||||||||||
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201-748-2 | ||||||||||||||
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8186 | ||||||||||||||
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128915 | ||||||||||||||
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- | ||||||||||||||
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175.18 | ||||||||||||||
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- | ||||||||||||||
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1H-indole-3-acetic acid | ||||||||||||||
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indol-3-ylacetic acid | ||||||||||||||
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Not applicable | ||||||||||||||
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Not applicable | ||||||||||||||
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Not applicable | ||||||||||||||
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Not applicable | ||||||||||||||
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Colourless to pale pink crystals | ||||||||||||||
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| Commercial |
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Current | |||
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Circa 1940s, developed; 1946, first introduced | |||
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Often supplied as a dustable powder or as water soluble tablets | |||
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Indole-3-acetic acid is produced commercially using microbial fermentation processes. Specific strains of bacteria or fungi, such as Streptomyces fradiae or Rhizobium sp. are selected for their high production capabilities. The microorganisms are cultured under optimised conditions and incubated in a suitable medium, often supplemented with L-tryptophan, which is a precursor for Indole-3-acetic acid production. After fermentation, Indole-3-acetic acid is extracted from the culture medium and purified using techniques like thin-layer chromatography and high-performance liquid chromatography | |||
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Data for the amount of life cycle GHGs produced by indolylacetic acid are not available in the public domain. However, whilst estimates vary, similar small molecules emit roughly 0.5-1.0 kg CO₂e per kg of product under conventional energy mixes. |
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1500 | A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 5 = Verified data used for regulatory purposes |
High | ||||||||
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1000000 | L3 L = Pesticide manuals and hard copy reference books / other sources Ethanol3 = Unverified data of known source |
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| 65000 | L3 L = Pesticide manuals and hard copy reference books / other sources Diethyl ether3 = Unverified data of known source |
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| 65000 | L3 L = Pesticide manuals and hard copy reference books / other sources Acetone3 = Unverified data of known source |
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| 20000 | L3 L = Pesticide manuals and hard copy reference books / other sources Chloroform3 = Unverified data of known source |
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167 | A3 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 3 = Unverified data of known source |
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363 | A3 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 3 = Unverified data of known source |
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171 | E4 E = Manufacturers safety data sheets 4 = Verified data |
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2.57 X 1001 | Calculated | - | |||||||
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1.41 | A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 5 = Verified data used for regulatory purposes |
Low | ||||||||
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1.576 | E4 E = Manufacturers safety data sheets 4 = Verified data |
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4.75 | A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 5 = Verified data used for regulatory purposes |
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| Weak acid | |||||||||||
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0.021 | A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 4 = Verified data |
Low volatility | ||||||||
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2.3 X 10-06 | A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 5 = Verified data used for regulatory purposes |
Non-volatile | ||||||||
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Neutral: max at 220nm, shoulders at 200nm, 280nm | A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 5 = Verified data used for regulatory purposes |
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| Degradation |
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General literature reports rapid degradation in soil | ||||||||||
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- | B2 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 2 = Unverified data of unknown source |
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Unstable in UV light | ||||||||||
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Stable | B2 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 2 = Unverified data of unknown source |
Stable | |||||||
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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. | ||||||||||
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| Soil adsorption and mobility |
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| Fate indices |
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Cannot be calculated | - | - | |||||||||||||||||||||||||
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| Known metabolites |
None
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| Terrestrial ecotoxicology |
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> 5000 | A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) Rat5 = Verified data used for regulatory purposes |
Low | ||||||||
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| Aquatic ecotoxicology |
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> 1.69 | F3 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment ) Scenedesmus quadricauda3 = Unverified data of known source |
Moderate | ||||||||
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| Regulatory Threshold Levels (RTLs) |
Note: These RTLs have been calculated using the regulatory approach used in the European Union and based on ecotoxocity values in the PPDB.
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500 | Worst case of acute and chronic mammals | |||
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No data | No data for acute and chronic birds | |||
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No data | No data for acute and chronic earthworms | |||
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No data | No data for non-target plants vegetative vigour and seedling emergence | |||
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No data | No data for contact and oral honeybees | |||
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No data | No data for parasitic wasps and predatory mites | |||
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No data | No data for temperate acute and chronic fish | |||
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No data | No data for temperate acute and chronic aquatic invertebrates | |||
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0.169 | Worst case of free-floating plants, rooted plants, acute and chronic algae |
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| General |
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Low (class I) | - | - | ||||||||
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> 5000 | A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) Rat5 = Verified data used for regulatory purposes |
Low | ||||||||
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> 2000 | A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) Rat5 = Verified data used for regulatory purposes |
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> 1.77 | A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) Rat5 = Verified data used for regulatory purposes |
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Intraperitoneal LD₅₀ = 150 mg kg⁻¹ | V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) Mouse3 = Unverified data of known source |
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Not allocated | A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 5 = Verified data used for regulatory purposes |
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Not allocated | A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 5 = Verified data used for regulatory purposes |
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0.055 | A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) Mouse SF=9005 = Verified data used for regulatory purposes |
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11.3 | A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 4 = Verified data |
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Not expected to pose a significant risk | |||||||||
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Not expected to pose a significant risk | ||||||||||
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| Health issues |
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May cause respiratory problems | ||||||||||||||||||||||||||||
| Handling issues |
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Light sensitive Not explosive or oxidising Not expected to auto-ignite; Not highly flammable |
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Health: H315, H319, H335 | |||
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Not listed (Not listed) | |||
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Limited shelf life. Store at -20 DegC |
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indolylacetic acid | ||
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AIA | ||
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| Record last updated: | 28/11/2025 |
| 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 |
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