3,7-dimethyloct-1-en-3-ol

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed according to OECD 429 and GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Version / remarks:

adopted 22 July 2010

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Version / remarks:

Commission Regulation (EC) No. 440/2008, B.42: “Skin Sensitisation: Local Lymph Node Assay”, updated 06 July 2012.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

3,7-dimethyloct-1-en-3-ol

EC Number:

242-358-2

EC Name:

3,7-dimethyloct-1-en-3-ol

Cas Number:

18479-49-7

Molecular formula:

C10H20O

IUPAC Name:

3,7-dimethyloct-1-en-3-ol

Test material form:

liquid

In vivo test system

Test animals

Species:

mouse

Strain:

CBA/Ca

Remarks:

CBA/CaOlaHsd

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
Source: Envigo RMS B.V., Inc Postbus 6174 5960 AD Horst / The Netherlands
Age (beginning of treatment): 1st pre-test and main study: 11 - 12 weeks 2nd pre-test: 10 - 11 weeks
Main Study: 10 - 11 weeks
Identification: The animals were distributed into the test groups at random. All animals belonging to the same experimental group were kept in one cage. In the main experiment, the animals were identified by tail tags. In the pre-experiment, animals were identified by cage number.
Acclimation: At least 5 days prior to the start of dosing under test conditions after health examination. Only animals without any visible signs of illness were used for the study.

Study design: in vivo (LLNA)

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

10, 25 and 50 %

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:

All calculations conducted on the DPM values, were performed with a validated test script of “R”, a language and environment for statistical computing and graphics.
Within the program a statistical analysis was conducted on the DPM values to assess whether the difference was statistically significant between the test item groups and negative control group. Statistical significance was set at the five per cent level (p < 0.05). Additionally, the Dean-Dixon-Test and Grubb’s Test were used for identification of possible outliers.

Results and discussion

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 positive control experiment was performed using CBA/CaOlaHsd mice in April 2016.
Result: 25 % α-Hexylcinnamaldehyde (in acetone/olive oil, 4+1 v/v): S.I. 7.84

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

1

Test group / Remarks:

vehicle control group (acetone/olive oil (4:1 v/v)

Remarks on result:

other: vehicle control group (acetone/olive oil (4:1 v/v)

Results 2

Key result

Parameter:

SI

Value:

1.1

Test group / Remarks:

10% 3,7-dimethyloct-1-en-3-ol

Remarks on result:

other: - vehicle control group (acetone/olive oil (4:1 v/v)

Results 3

Key result

Parameter:

SI

Value:

2.4

Test group / Remarks:

25% 3,7-dimethyloct-1-en-3-ol

Remarks on result:

other: vehicle control group (acetone/olive oil (4:1 v/v)

Results 4

Key result

Parameter:

SI

Value:

2.3

Test group / Remarks:

50% 3,7-dimethyloct-1-en-3-ol

Remarks on result:

other: vehicle control group (acetone/olive oil (4:1 v/v)

Results 5

Parameter:

other: disintegration per inute (DPM)

Remarks on result:

other: - vehicle control group: mean DPM per animal 1776.9 - 10% 3,7-dimethyloct-1-en-3-ol: mean DPM per animal 1954.3 - 25% 3,7-dimethyloct-1-en-3-ol: mean DPM per animal 4208.2 - 50% 3,7-dimethyloct-1-en-3-ol: mean DPM per animal 4102.1

Any other information on results incl. tables

No EC3 calculated, since all Stimulation indices (S.I.) are below the threshold of 3

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The test item 3,7-dimethyloct-1-en-3-ol was not a skin sensitiser under the test conditions of this study.

Executive summary:

In the study the test item 3,7-dimethyloct-1-en-3-ol formulated in acetone/olive oil (4:1 v/v) was assessed for its possible skin sensitising potential.

For this purpose a local lymph node assay was performed using test item concentrations of 10, 25, and 50%. The highest concentration tested was the highest concentration that could be achieved whilst avoiding systemic toxicity and excessive local skin irritation as confirmed by two pre-experiments.

No cases of mortality were observed. On day 1 after application, the animals treated with the high dose of the test item showed squinted eyes. On test days 2 to 4, the animals treated with the high dose of the test item showed an erythema of the ear skin (score 1). Moreover, a transient erythema of the ear skin was observed in the animals treated with the mid dose of the test item on day 4 only.

Due to technical reasons, the disintegrations per minute (DPM value) from animal 12 could not be measured (vial was spilled during preparation). However, this has no influence on the validity of the study, since all Stimulation indices (S.I.) determined for this dose group as well as the mean S.I. of this dose group are below the threshold index of 3.

A statistically significant increase in DPM values (p<0.05) was observed in the mid and high dose group, respectively, when compared to the vehicle control group. However this was considered to be not biologically relevant, since the S.I. determined for these dose groups were below the threshold index of 3. An outlier (DPM value for animal 6) was detected in the Grubb’s Test, but not in the Dean-Dixon-Test, and was therefore not excluded from any calculations.

In this study Stimulation Indices (S.I.) of 1.1, 2.4 and 2.3 were determined with the test item at concentrations of 10, 25, and 50% in acetone/olive oil (4:1 v/v), respectively.

Conclusion: The test item 3,7-dimethyloct-1-en-3-ol was not a skin sensitiser under the test conditions of this study.