Decahydro-2-naphthyl acetate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

08 February 2016 - 30 March 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

In the absence of prior testing, the Murine Local Lymph Node Assay (LLNA) was the endorsed method to assess skin sensitisation potential under REACH, as no EU-OECD in vitro tests for skin sensitisation had been validated. However, the REACH Annex VII information requirements were revised in 2016 to endorse a battery of in vitro assays for skin sensitisation. The LLNA for skin sensitisation (OECD 429) was initiated and completed for Decahydro-2-naphthyl acetate prior to changes in regulatory guidance. The reliable and GLP compliant in vivo LLNA was considered sufficient to fulfil the endpoint.

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:

2010

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Version / remarks:

2003

Deviations:

no

GLP compliance:

yes

Remarks:

Exceptions: Misture analysis and solubility not performed

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Decahydro-2-naphthyl acetate

EC Number:

234-054-3

EC Name:

Decahydro-2-naphthyl acetate

Cas Number:

10519-11-6

Molecular formula:

C12H20O2

IUPAC Name:

decahydronaphthalen-2-yl acetate

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/JcrHSD

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Females nulliparous and non-pregnant: yes
- Age at study initiation: Born 08 January 2016, study initiated on 16 March 2016
- Weight at study initiation: 18.3 to 21.7g
- Housing: 1 to 5 per cage in polycarbonate box with bedding
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 23°C
- Humidity (%): 25 to 91% relative humidity
- Air changes (per hr): 10+ air changes per hour
- Photoperiod (hrs dark / hrs light): 12-hour light/dark cycle
- IN-LIFE DATES: From: 08 January 2016 To: 21 March 2016

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

25, 50 and 100%

No. of animals per dose:

5

Details on study design:

PRE-SCREEN TESTS: A range-finding test was not conduced for this study.

MAIN STUDY

ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: LLNA
- Criteria used to consider a positive response: Incorporation of tritiated thymidine was measured by liquid scintillation counting as disintegrations per minute (DPM) from paired lymph nodes of each animal, and mean DPM/animal were calculated for each group.

TREATMENT PREPARATION AND ADMINISTRATION: On Days 1, 2 and 3, each test animal received an open application of 25µL of the appropriate dilution (25 or 50%) of the test item in 4:1 v/v acetone:olive oil vehicle, or 100% test item, to the dorsum of both ears. Animals were given a two-day rest period on Days 4 and 5. On Day 6 of the study, test animals were injected in the tail vein with tritiated methyl-thymidine. Animals were sacrificed 5 hours after injection and the draining auricular lymph nodes were excised and processed.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

A one-way parametric analysis of variance (ANOVA) with Dunnett's Multiple Comparisons Test was performed on DPM counts. As the SI was <3 in all test groups, an extrapolated EC3 was not calculated.

Results and discussion

Positive control results:

One positive control animal was found dead on Day 6. Three animal (surviving to termination) lost weight. The mean DPM count was 12104 (standard deviation: 4050).

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

0.6

Variability:

Mean DPM count: 1603 (standard deviation: 810)

Test group / Remarks:

25%

Results 2

Parameter:

SI

Value:

1

Variability:

Mean DPM count: 2403 (standard deviation: 744)

Test group / Remarks:

50%

Results 3

Key result

Parameter:

SI

Value:

1.2

Variability:

Mean DPM count: 2981 (standard deviation: 1009)

Test group / Remarks:

100%

Cellular proliferation data / Observations:

DETAILS ON STIMULATION INDEX CALCULATION: Ratio of Test item to Vehicle control derived for each test group based on group mean DPM. Vehicle Control mean DPM count: 2472 (standard deviation: 1059).

EC3 CALCULATION: An extrapolated EC3 was not calculated since the SI was <3 in all test groups.

CLINICAL OBSERVATIONS: All test item treatment animals appeared normal for the duration of the study.

BODY WEIGHTS: 1 to 3 animals in each test group lost weight during the study.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The skin sensitisation potential of the test item was determined in a local lymph node assay (LLNA) in female CBA/JcrHSD mice. The test item produced a stimulation index <3 at concentrations up to and including 100%.

Executive summary:

The skin sensitisation potential of the test item was determined in a local lymph node assay (LLNA) in female CBA/JcrHSD mice. Doses of 25, 50 and 100% test item was applied to the dorsum of both ears on Days 1, 2 and 3, alongside a vehicle control and positive control. All animals were given a two-day rest period on Days 4 and 5 and animals were injected with tritiated methyl-thymidine and sacrificed on Day 6. The test item produced a stimulation index <3 in all groups of test animals. The study is reliable without restriction (Klimisch 1) as it was GLP-compliant and was conducted according to OECD Guideline 429 and EPA OCSPP 870.2600.