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Toxicological information

Skin sensitisation

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Administrative data

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

Data source

Reference
Reference Type:
publication
Title:
Conjugated Dienes as Prohaptens in Contact Allergy: In Vivo and in Vitro Studies of Structure-Activity Relationships, Sensitizing Capacity, and Metabolic Activation
Author:
Bergstrom M A
Year:
2006
Bibliographic source:
Chem. Res. Toxicol. 2006, 19, 760-769

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
yes
Remarks:
Lack of data on test animals and housing conditions.
GLP compliance:
not specified
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
Type:
Constituent

In vivo test system

Test animals

Species:
mouse
Strain:
not specified
Sex:
not specified

Study design: in vivo (LLNA)

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
0 (vehicle), 1, 5 10, 15 and 25% w/v
No. of animals per dose:
three females
Details on study design:
MAIN STUDY

ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: murine local lymph node assay.
- Criteria used to consider a positive response:
Test materials that at one or more concentrations gave rise to an stimulation index (SI) greater than 3 were considered to be sensitizers in the LLNA.
The sensitizing potency of the test compound was classified according to the following: <0.1, extreme; ≥0.1-<1, strong; ≥1- <10, moderate; and ≥10-<100, weak ((ECETOC (2003), Kimber et al. (2003)).
Positive control substance(s):
other: The results of this study were compared with the prohaptenic cinnamic alcohol and its reactive metabolite cinnamic aldehyde.
Statistics:
Results were expressed as mean dpm/lymph node for each experimental group and as stimulation index (SI), i.e., test group/control group ratio.
EC3 values were calculated by linear interpolation (Basketter et al. (1999)) and used to determine the sensitizing potency of the test substance.

Results and discussion

Positive control results:
Prohaptenic cinnamic alcohol and its reactive metabolite cinnamic aldehyde gave EC3 values of 1.5 (20.1%) and 0.10 M (1.3%), respectively (Elahi et al. (2004)).

In vivo (LLNA)

Resultsopen allclose all
Key result
Parameter:
SI
Value:
1.1
Test group / Remarks:
1 % w/v
Key result
Parameter:
SI
Value:
1.5
Test group / Remarks:
5 % w/v
Key result
Parameter:
SI
Value:
3.4
Test group / Remarks:
10 % w/v
Key result
Parameter:
SI
Value:
8.9
Test group / Remarks:
15 % w/v
Key result
Parameter:
SI
Value:
23
Test group / Remarks:
25% w/v
Key result
Parameter:
EC3
Value:
8.9
Remarks on result:
other: EC3= estimated concentration to induce a Stimulation index of 3

Any other information on results incl. tables

Table 1. LLNA results for alpha terpinene

Alpha terpinene and test concentrations

(% w/v)

[3H]thymidine

incorporation

(dpm/lymph node)

SI

 

EC3 value of  

Alpha terpinene and test concentrations

(% w/v)

sensitizing potency

% w/v

M

0

755

 

8.9

0.65

moderate

1

848

1.1

5

1153

1.5

10

2595

3.4

15

6740

8.9

25

17176

23

Applicant's summary and conclusion

Interpretation of results:
other: Category 1B (CLP Regulation EC no. 1272/2008)
Conclusions:
Based on the results of this study, alpha terpinene was shown to be sensitizer of moderate potency with the EC3 value of 0.65 M (8.9 % w/v). The SI was greater than 3 at the concentrations of 10, 15 and 25 %.
Executive summary:

The murine LLNA assay was used in this study to assess the sensitizing potency of alpha terpinene which was tested at concentrations of 0 (acetone/olive oil, 4:1 v/v), 1, 5, 10, 15 and 25 (% w/v) using mice in groups of three. The results were expressed as mean dpm/lymph node for each experimental group and as stimulation index (SI), i.e., test group/control group ratio. Test material that at one or more concentrations gave rise to an SI greater than 3 were considered to be sensitizers in the LLNA. The results of this study were compared with the prohaptenic cinnamic alcohol and its reactive metabolite cinnamic aldehyde, which have EC3 values of 1.5 (20.1%) and 0.10 M (1.3%), respectively. The results demonstrated that the SI was greater than 3 at the concentrations of 10, 15 and 25 % of alpha terpinene. Based on these results, alpha terpinene was shown to be a sensitizer of moderate potency with EC3 value of 0.65 M (8.9 % w/v).