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Description of key information

Skin sensitisation (OECD429): sensitising (read-across)

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Referenceopen allclose all

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study performed according to OECD 429 and GLP.
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of study:
mouse local lymph node assay (LLNA)
Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS- Source: Envigo RMS B.V., Inc- Age at study initiation: Pre-test: 10 - 11 weeksMain study: 9 - 10 weeks- Weight at study initiation: 18.6 - 21.2 g- Assigned to test groups randomly: yes- Housing: animals were distributed into the test groups at random, all animals belonging to the same experimental group were kept in one cage- Diet: 2018C Teklad Global 18 % protein rodent diet (certified), ad libitum- Water: tap water ad libitum- Acclimation period: at least 5 days prior to the start of dosing under test conditions after health examinationENVIRONMENTAL CONDITIONS- Temperature (°C): 22 ± 2 - Humidity (%): 45 - 65- Photoperiod (hrs dark / hrs light): 12 / 12
Vehicle:
dimethylformamide
Concentration:
25, 50 and 100%
No. of animals per dose:
5
Details on study design:
Three groups each of five female mice were treated with different concentrations of the test item by topical application at the dorsum of each ear once daily each on three consecutive days. A control group of five mice was treated with the vehicle only. Five days after the first topical application, the mice were intravenously injected into a tail vein with radio-labelled thymidine (3H-methyl thymidine; 3HTdR). Approximately five hours after intravenous injection, the mice were sacrificed and the draining auricular lymph nodes were excised and pooled per animal. Single cell suspensions of lymph node cells were prepared from pooled lymph nodes, which were subsequently washed and incubated with trichloroacetic acid overnight. The proliferative capacity of pooled lymph node cells were then determined by the incorporation of 3H-methyl thymidine measured in a β-scintillation counter.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
A statistical analysis was conducted on the ear weights to assess whether the difference was statistically significant between test item groups and negative control (vehicle) group. For all statistical calculations validated statistical program R Script DecisionTree_2.Rnw was used. Statistical significance was set at the five per cent level (p < 0.05).
Positive control results:
The sensitivity and reliability of the experimental technique employed was assessed by use of α-hexyl cinnamaldehyde dissolved in acetone/olive oil (4+1 v/v) (compound listed in OECD 429 Guideline) which is known to have skin sensitisation properties in mice. The periodic positivecontrol experiment was performed using CBA/CaOlaHsd mice in October 2015.Result: - 10 % α-Hexylcinnamaldehyde (in acetone/olive oil, 4+1 v/v): S.I. 4.23- 25 % α-Hexylcinnamaldehyde: S.I. 17.56
Key result
Parameter:
EC3
Value:
35.5
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: - vehicle control group (DMF): mean DPM per animal: 835.5, SD 335.78- 25% Linalool: mean DPM per animal: 2073.9, SD 433.09- 50% Linalool: mean DPM per animal: 3104.5, SD 814.95- 100% Linalool: mean DPM per animal: 3564.3, SD 1086.55
Parameter:
SI
Value:
1
Test group / Remarks:
vehicle control group DMF
Parameter:
SI
Value:
2.48
Test group / Remarks:
25% Linalool
Parameter:
SI
Value:
3.72
Test group / Remarks:
50% Linalool
Parameter:
SI
Value:
4.27
Test group / Remarks:
100% Linalool

EC3 = 35.5% (w/v)

Interpretation of results:
sensitising
Remarks:
Criteria used for interpretation of results: EU
Conclusions:
The test item Linalool was found to be a skin sensitiser and an EC3 value of 35.5 % (w/v) was derived.
Executive summary:

In the study the test item Linalool formulated in water-free dimethylformamide (DMF) was assessed for its possible skin sensitising potential. For this purpose a local lymph node assay was performed using test item concentrations of 25, 50, (w/v) and 100%.

No cases of mortality were observed. From day 1 to 4, the animals showed an erythema of the ear skin (Score 1, animals treated with 25%: 1h after the third application, animals treated with 50%: 1h after the second and third application, animals treated with 100%: 1h after the first and second application, on days 3 and 4). Transiently, especially after applications, nervousness, tumbling and burrowing in the bedding were observed in some of the animals (for details see Appendix 3). A relevant increase in ear weights was not observed in any of the treated groups in comparison to the vehicle control group.

In this study Stimulation Indices (S.I.) of 2.48, 3.72, and 4.27 were determined with the test item at concentrations of 25, 50, and 100%, respectively.

The test item Linalool was found to be a skin sensitiser and an EC3 value of 35.5 % (w/v) was derived. The substance has to be classified according to criteria outlined in Annex I of the Regulation (EC) No. 1272/2008.

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
See attached justification
Reason / purpose:
read-across source
Positive control results:
The sensitivity and reliability of the experimental technique employed was assessed by use of α-hexyl cinnamaldehyde dissolved in acetone/olive oil (4+1 v/v) (compound listed in OECD 429 Guideline) which is known to have skin sensitisation properties in mice. The periodic positivecontrol experiment was performed using CBA/CaOlaHsd mice in October 2015.Result: - 10 % α-Hexylcinnamaldehyde (in acetone/olive oil, 4+1 v/v): S.I. 4.23- 25 % α-Hexylcinnamaldehyde: S.I. 17.56
Key result
Parameter:
EC3
Value:
35.5
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: - vehicle control group (DMF): mean DPM per animal: 835.5, SD 335.78- 25% Linalool: mean DPM per animal: 2073.9, SD 433.09- 50% Linalool: mean DPM per animal: 3104.5, SD 814.95- 100% Linalool: mean DPM per animal: 3564.3, SD 1086.55
Parameter:
SI
Value:
1
Variability:
Vehicle control group (DMF)
Parameter:
SI
Value:
2.48
Test group / Remarks:
25% Linalool
Parameter:
SI
Value:
3.72
Test group / Remarks:
50% Linalool
Parameter:
SI
Value:
4.27
Test group / Remarks:
100% Linalool

EC3 = 35.5% (w/v)

Interpretation of results:
sensitising
Remarks:
Criteria used for interpretation of results: EU
Conclusions:
The test item Linalool was found to be a skin sensitiser and an EC3 value of 35.5 % (w/v) was derived. This result is used for read-across to ethyllinalyl acetate.
Executive summary:

In the study the test item Linalool formulated in water-free dimethylformamide (DMF) was assessed for its possible skin sensitising potential. For this purpose a local lymph node assay was performed using test item concentrations of 25, 50, (w/v) and 100%.

No cases of mortality were observed. From day 1 to 4, the animals showed an erythema of the ear skin (Score 1, animals treated with 25%: 1h after the third application, animals treated with 50%: 1h after the second and third application, animals treated with 100%: 1h after the first and second application, on days 3 and 4). Transiently, especially after applications, nervousness, tumbling and burrowing in the bedding were observed in some of the animals (for details see Appendix 3). A relevant increase in ear weights was not observed in any of the treated groups in comparison to the vehicle control group.

In this study Stimulation Indices (S.I.) of 2.48, 3.72, and 4.27 were determined with the test item at concentrations of 25, 50, and 100%, respectively.

The test item Linalool was found to be a skin sensitiser and an EC3 value of 35.5 % (w/v) was derived. The substance has to be classified according to criteria outlined in Annex I of the Regulation (EC) No. 1272/2008. This result is used for read-across to ethyllinalyl acetate.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

Skin sensitisation

Three studies are available for this endpoint, all for read-across substances. The key study is a skin sensitisation study performed according to OECD 429 and in compliance with GLP. In the study the test item Linalool formulated in water-free dimethylformamide (DMF) was assessed for its possible skin sensitising potential. For this purpose a local lymph node assay was performed using test item concentrations of 25, 50, (w/v) and 100%. No cases of mortality were observed. From day 1 to 4, the animals showed an erythema of the ear skin (Score 1, animals treated with 25%: 1h after the third application, animals treated with 50%: 1h after the second and third application, animals treated with 100%: 1h after the first and second application, on days 3 and 4). Transiently, especially after applications, nervousness, tumbling and burrowing in the bedding were observed in some of the animals (for details see Appendix 3). A relevant increase in ear weights was not observed in any of the treated groups in comparison to the vehicle control group. In this study Stimulation Indices (S.I.) of 2.48, 3.72, and 4.27 were determined with the test item at concentrations of 25, 50, and 100%, respectively. The test item Linalool was found to be a skin sensitiser and an EC3 value of 35.5 % (w/v) was derived. This result is supported by a study in which an EC3 value of 48.2% (w/v) was found for Ethyllinalool. Another study exists for linalool in which a hRIPT with a relatively low concentration of linalool (12.7%) resulted in a negative outcome for skin sensitisation. All results are used for read-across to ethylinalyl acetate and taking this all together the substance should be considered a skin sensitiser at least at concentrations above 12.7%.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Based on the available data, ethyllinalyl acetate is considered to be a skin sensitiser (Category 1B / H317) in accordance with the criteria outlined in Annex I of the CLP Regulation (1272/2008/EC).