Alpha-terpineol	Last updated: 12/02/2025
(Also known as: Tea tree oil extract; Oil of Melaleuca; TTO; Carvomenthenol; Terpenol)

---

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
	Ecotoxicity Moderate alert: Fish acute ecotoxicity: Moderate; Bees acute contact ecotoxicity: Moderate Warning: Significant data are missing	Human health Low alert Warning: Significant data are missing

GENERAL INFORMATION

Description	A component of various essential oils including turpentine and tea tree and which is used to control various fungal pathogens on a wide range of crops
Example pests controlled	Various fungal pathogens including powdery mildew and early blight
Example applications	Potatoes; Carrots; Tomatoes; Cucumbers; Fruit; Ornamentals
Efficacy & activity	-
Appearance and life cycle	-
Availability status	Current
Introduction & key dates	1920s, Tea tree oil first reported
Taxonomic classification	-

GB regulatory status

GB COPR regulatory status	Not approved
Date COPR inclusion expires	Not applicable
GB LERAP status	Not applicable

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status	Approved (as Tea tree oil)
Dossier rapporteur/co-rapporteur	Poland/Bulgaria
Date EC 1107/2009 inclusion expires	31/01/2026
EU Candidate for substitution (CfS)	No
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	-

Chemical structure

Isomerism	-
Chemical formula	C₁₀H₁₈O
Canonical SMILES	CC1=CCC(CC1)C(C)(C)O
Isomeric SMILES	No data
International Chemical Identifier key (InChIKey)	WUOACPNHFRMFPN-UHFFFAOYSA-N
International Chemical Identifier (InChI)	InChI=1S/C10H18O/c1-8-4-6-9(7-5-8)10(2,3)11/h4,9,11H,5-7H2,1-3H3
2D structure diagram/image available?	Yes

General status

Biopesticide type	Fungicide
Substance groups	Plant-derived substance
Minimum active substance purity	-
Known relevant impurities	-
Substance origin	Natural
Mode of action	Tea tree oil appears to disrupt the permeability barrier of microbial cell membrane structures, causing loss of chemiosmotic control.
Substance source	Alpha-terpineol was discovered in the late 19th century as a component of various essential oils including turpentine oil and tea-tree oil
Substance production	Alpha-terpineol is often produced commercially by hydrating alpha-pinene, which is derived from turpentine oil. The process involves the addition of water to alpha-pinene in the presence of an acid catalyst, resulting in the formation of alpha-terpineol. Alternatively, it can be produced by the hydration of limonene, a monoterpene found in citrus oils. Microbial transformation has also ben used for its production using monoterpenes such as limonene, alpha-pinene, and beta-pinene. Microorganisms like Saccharomyces cerevisiaeare genetically engineered to express enzymes that convert these monoterpenes into alpha-terpineol.
Uses	Crop protection
Target pests	Various fungal pathogens including powdery mildew and early blight
Target host	Potatoes; Carrots; Tomatoes; Cucumbers; Fruit; Ornamentals
Farming system suitability	Tea tree oil is suitable for use in all farming systems where approved for use in that country
CAS RN	98-55-5
EC number	202-680-6
CIPAC number	-
US EPA chemical code	-
PubChem CID	-
Molecular mass	154.25
PIN (Preferred Identification Name)	-
IUPAC name	2-[(4-methyl-1-cyclohex-3-enyl)]propan-2-ol
CAS name	α-terpineol
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	Clear liquid
Related substances & organisms	terpinen-4-ol gamma-terpinene alpha-terpinene alpha-terpinoline para-cymene alpha-pinene

Formulations

Property	Product	Manufacturer
Example products	Timorex	BioMor Latvija
Formulation and application details	Tea tree oil is usually supplied as an emulsifable concentrate that is diluted and used as a foliar spray

ENVIRONMENTAL FATE

Property		Value	Source; quality score; and other information	Interpretation
Solubility - In water at 20 °C (mg l⁻¹)		710	V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source	Moderate
Solubility - In organic solvents at 20 °C (mg l⁻¹)		-	-	-
Melting point (°C)		-	-	-
Boiling point (°C)		220	V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source	-
Degradation point (°C)		-	-	-
Flashpoint (°C)		-	-	-
Octanol-water partition coefficient at pH 7, 20 °C	P	9.55 X 1002	Calculated	-
	Log P	2.98	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	Moderate
Fat solubility of residues	Solubility	-	-	-
	Data type	-	-	-
Density (g ml⁻¹)		-	-	-
Dissociation constant pKa) at 25 °C		Not applicable	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	-
		No dissociation
Vapour pressure at 20 °C (mPa)		562.6	V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source	Highly volatile. If applied directly to plants or soil, drift is a concern & mitigation is advisable
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)		-	-	-

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	-
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	-
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	Kd (mL g⁻¹)	-	-	-
	Koc (mL g⁻¹)	-
	Notes and range	-
Freundlich	Kf (mL g⁻¹)	-	-	-
	Kfoc (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)		5170	V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source 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)	17.1	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 as vapour mg l⁻¹ air	Moderate
	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)		6.6	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 Oncorhynchus mykiss	Moderate
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)		-	-	-
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)		-	-	-
Mesocosm study data	NOEAEC mg l⁻¹	-	-	-
	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)		5170	V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source Rat	Low
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)		-	-	-
Mammals - Inhalation LC₅₀ (mg l⁻¹)		-	-	-
Other Mammal toxicity endpoints		Intramuscular LD₅₀ = 2000 mg kg⁻¹	V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source Mouse	-
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		-	-	-

Health issues

Specific human health issues		Carcinogen Genotoxic Endocrine disruptor XNo, known not to cause a problem A0 A = Chromosome aberration (EFSA database) 0 = No data ; B0 B = DNA damage/repair (EFSA database) 0 = No data ; C0 C = Gene mutation (EFSA database) 0 = No data ; D0 D = Genome mutation (EFSA database) 0 = No data ; E0 E = Unspecified genotoxicity type (miscellaneous data source) 0 = No data No data found Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant No data found No data found XNo, known not to cause a problem Respiratory tract irritant Skin irritant Skin sensitiser ?Possibly, status not identified ?Possibly, status not identified XNo, known not to cause a problem Eye irritant Phototoxicant   ?Possibly, status not identified No data found
General human health issues		No further information available

Handling issues

Property	Value and interpretation
General	Not explosive or oxidising
CLP classification 2013	Health: H315, H319, H335 Environment: H411
WHO Classification	Not listed (Not listed)
UN Number	-
Waste disposal & packaging	-
Shelf-life, storage, stability and reactivity	-

TRANSLATIONS

Language	Name
English	alpha-terpineol
French	-
German	-
Danish	-
Italian	-
Spanish	-
Greek	-
Polish	-
Swedish	-
Hungarian	-
Dutch	-
Norwegian	-

---

Record last updated:	12/02/2025
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