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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report date:
1989

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
- Principle of test: The test was carried out to determine whether Tea Tree Oil is a skin sensitiser, according to the Magnusson & Kligmann method (Magnusson & Kligmann 1969, 1970, Magnusson 1980).
- Short description of test conditions: Test animals were exposed intradermally and epidermally to the test material, along with an adjuvant to enhance the immune reaction. The guinea pigs were subsequently exposed to a lower concentration of the test material, and the incidence of skin reaction noted.
- Parameters analysed / observed: Erythemal reactions, signs of toxicity and abnormal behaviour.
GLP compliance:
no
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
This study was conducted prior to development of the LLNA method and its introduction as the default in-vivo method for REACH registration.

Test material

Constituent 1
Reference substance name:
Melaleuca alternifolia, ext.
EC Number:
285-377-1
EC Name:
Melaleuca alternifolia, ext.
Cas Number:
85085-48-9
Molecular formula:
Not applicable (a generic molecular formula cannot be provided for this specific UVCB substance).
IUPAC Name:
Essential oil of melaleuca alternifolia
Test material form:
liquid
Specific details on test material used for the study:
Batch no.: 88/375.

Purity: 100%.

In vivo test system

Test animals

Species:
guinea pig
Strain:
other: HA strain - albino
Sex:
not specified
Details on test animals and environmental conditions:
- Source: Not specified.
- Age at study initiation: Not specified.
- Weight at study initiation: 200 - 500 g.
- Housing: Not described.
- Diet: Not specified.
- Water: Not specified.
- Acclimation period: Not described.
- Environmental conditions: Not described.

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal
Vehicle:
other: saline / Freund's complete adjuvant
Concentration / amount:
0.1 ml. 1:1:1 mixture of Tea Tree Oil, saline, and Freund's complete adjuvant.
Adequacy of induction:
not specified
Route:
intradermal
Vehicle:
paraffin oil
Concentration / amount:
0.1 ml. 5% Tea Tree Oil in paraffin oil B.P.
Adequacy of induction:
not specified
Route:
epicutaneous, occlusive
Vehicle:
unchanged (no vehicle)
Concentration / amount:
Not specified
Day(s)/duration:
48 hours
Adequacy of induction:
not specified
Challenge
Route:
epicutaneous, occlusive
Vehicle:
petrolatum
Concentration / amount:
30% w/w test sample in petroleum jelly
Day(s)/duration:
24 hours
Adequacy of challenge:
highest non-irritant concentration
No. of animals per dose:
20 test animals and 20 control animals.
Details on study design:
- Induction procedure: The induction procedure consisted of 2 intradermal injections (0.1ml each) and an epidermal induction application. In the case of the epidermal induction application, the substance was applied epicutaneously over the injection sites one week after injection and held under occlusion for 48 hours.
- Induction test concentrations: One induction injection consisted of 5% Tea Tree Oil in paraffin oil B.P. The other was a 1:1:1 mixture of Tea Tree Oil, saline, and Freund's complete adjuvant. The undiluted test sample was used for the epidermal induction.
- Challenge exposure: Two weeks after the induction application, the animals were tested on one flank with the maximum subirritant concentration of the test compound in petroleum jelly (occlusive administration for 24 hours).
- Challenge concentrations: The subirritant dose used for challenge was 30% w/w test sample in petroleum jelly.
- Control: Control animals were treated with the vehcles alone during the induction period.
Challenge controls:
The control group was challenged with the vehicle and the test compound in subirritant concentration.
Positive control substance(s):
no

Results and discussion

Positive control results:
No positive controls were used in this study.

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
Challenge: 30% w/w test sample in petroleum jelly
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
None
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
Challenge: 30% w/w test sample in petroleum jelly
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
None
Remarks on result:
no indication of skin sensitisation

Any other information on results incl. tables

The guinea pigs appeared normal during the test period. The dermal challenge irritations did not produce irritant responses in either treated or control animals.

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Conclusions:
The test sample did not induce sensitization reactions after dermal challenge.
Executive summary:

Skin sensitization studies were carried out to determine whether Tea Tree Oil (Batch 88/375) was a skin sensitizing agent in the guinea pig. The test was carried out according to the Magnusson & Kligmann maximisation method.  20 albino guinea pigs were used for the test and control experiments respectively. The induction procedure consisted of two intradermal injections and an epidermal induction application. Two weeks after the induction application, the challenge dose was applied (subirritant dose, 30% w/w test sample in petroleum jelly). All animals were observed for signs of toxicity and abnormal behaviour during the experimental period. The guinea pigs appeared normal during the test period. The test sample did not induce sensitization reactions after dermal challenge.