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Para-cymene
Last updated: 17/09/2025
(Also known as: Tea tree oil extract; Oil of Melaleuca; TTO; Camphogen; p-cymene)
GENERAL INFORMATION
Description
A component of various essential oils including cumin oil (12-25%) and tea tree oil (0.5-8%) which is used to control various fungal pathogens on a wide range of crops
Examples of veterinary uses
-
Examples of species treated
-
Approval status
VMR 2013/2033 approval status (GB/UK)
-
EU Regulatory approval status
-
Chemical structure
Isomerism
Para-cymene (p-cymene) exhibits positional isomerism, a type of structural isomerism where the position of substituents on the aromatic ring varies. It consists of a benzene ring substituted with a methyl group and an isopropyl group in the para position, meaning they are located opposite each other on the ring. In addition to p-cymene, there are two other isomers: ortho-cymene, where the substituents are adjacent, and meta-cymene, where they are separated by one carbon atom. Para-cymene is the most naturally occurring isomer.
Chemical formula
C₁₀H₁₄
Canonical SMILES
CC1=CC=C(C=C1)C(C)C
Isomeric SMILES
No data
International Chemical Identifier key (InChIKey)
HFPZCAJZSCWRBC-UHFFFAOYSA-N
International Chemical Identifier (InChI)
InChI=1S/C10H14/c1-8(2)10-6-4-9(3)5-7-10/h4-8H,1-3H3
2D structure diagram/image available?
Yes
General status
Veterinary substance type
-
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.
Molecular targets
-
CAS RN
99-87-6
EC number
202-796-7
CIPAC number
-
US EPA chemical code
-
PubChem CID
-
Therapeutic Class
-
ATCvet Code
-
Controlled Drug?
-
Regulation 37/2010 MRL Classification
-
Molecular mass
134.22
PIN (Preferred Identification Name)
-
IUPAC name
1-methyl-4-isopropylbenzene
CAS name
para-cymene
Global Governance status: 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
-
Other status information
-
Physical state
Clear liquid
Related substances & organisms
Commercial
Property
Value
Availability status
Current
Introduction & key dates
1920s, Tea tree oil first reported
Example manufacturers & suppliers of products using this active now or historically
  • BioMor Latvija
Example products using this active
  • Timorex
Formulation and application details
Tea tree oil is usually supplied as an emulsifable concentrate that is diluted and used as a foliar spray
Commercial production
Para-cymene is commonly extracted from essential oils like cumin oil, tea-tree oil and thyme oil. The plant material is subjected to steam, which vaporises the para-cymene. The vapour is then condensed and collected. Fractional distillation or solvent extraction may also be used to separate para-cymene from other components in the essential oil. Para-cymene can be synthesised by alkylating toluene with propene in the presence of a catalyst.
Impact on climate of production and use
Data for specific plant oils is scarce. However, from publicly available data the carbon footprint of plant oils has been estimated at between 1.0 and 4.0 kg CO₂e per kg of oil. This depends on the plant oil content, agricultural practices and processing methods used.
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C at pH 7 (mg l⁻¹)
23.4
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)
177
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
2.75 X 1004 Calculated -
Log P
4.44
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
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)
1.94 X 1005
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)
- - -
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
Kd (mL g⁻¹)
- - Non-mobile
Koc (mL g⁻¹)
4732
Notes and range
EU dossier - estimated
Freundlich
Kf (mL g⁻¹)
- - -
Kfoc (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)
4750
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID )
3 = Unverified data of known source
Rat		 Low
Mammals - Short Term Oral NOAEL (mg kg⁻¹ bw d⁻¹)
- - -
Mammals - Long Term (Chronic) Oral NOAEL (mg kg⁻¹ bw d⁻¹)
- - -
Birds - Acute LD₅₀ (mg kg⁻¹)
- - -
Birds - Short term dietary LC₅₀ (mg kg⁻¹ bw d⁻¹)
- - -
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)
- - -
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹ dw soil)
> 1000
Q2 Q = Miscellaneous data from online sources
2 = Unverified data of unknown source
Expert judgement		 Low
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹ dw soil)
- - -
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)
> 100
Q2 Q = Miscellaneous data from online sources
2 = Unverified data of unknown source
Expert judgement		 Low
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)
- - -
Beneficial insects (Butterflies)
Contact
- - -
Notes
-
Oral
- - -
Notes
-
Aquatic ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Temperate Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
48.0
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
Cyprinodon variegatus marine species		 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)
6.5
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
Daphnia magna		 Moderate
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
- - -
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)
4750
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID )
3 = Unverified data of known source
Rat		 Low
Mammals - Short Term Oral NOAEL (mg kg⁻¹ bw d⁻¹)
- - -
Mammals - Long Term (Chronic) Oral NOAEL (mg kg⁻¹ bw d⁻¹)
- - -
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
- - -
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
- - -
Health issues
Specific human health issues (hazard-based)
Carcinogen
Genotoxic
Endocrine disruptor
No data found
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 No data found
Respiratory tract irritant Skin irritant Skin sensitiser
?Possibly, status not identified
✓Yes, known to cause a problem
XNo, known not to cause a problem
Eye irritant Phototoxicant  
✓Yes, known to cause a problem
 No data found  
General human health issues
No adverse health issues noted
Handling issues
Property
Value and interpretation
General
Not explosive or oxidising
Flammable
IMDG Transport Hazard Class 3
CLP classification 2013
Health: H304, H315, H319, H335
Handling: H226
Environment: H411
WHO Classification
Not listed (Not listed)
UN Number
UN2046
Waste disposal & packaging
-
Shelf-life, storage, stability and reactivity
-
TRANSLATIONS
Language
Name
English
para-cymene
French
-
German
-
Danish
-
Italian
-
Spanish
-
Greek
-
Polish
-
Swedish
-
Hungarian
-
Dutch
-
Norwegian
-
Record last updated: 17/09/2025
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

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