Ethyl isovalerate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

24.3.2016 - 07.07.2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

It is suspected that false positive LLNA results could be caused by some kind of detergent effect. Seeing that "emulsion formation" was the cause of the inconclusive output of the in vitro test battery, no LLNA test was conducted.

Test material

Test material information

Constituent 1

Reference substance name:

3-methylbutyl isovalerate

EC Number:

211-536-1

EC Name:

3-methylbutyl isovalerate

Cas Number:

659-70-1

Molecular formula:

C10H20O2

IUPAC Name:

3-methylbutyl 3-methylbutanoate

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Microbiological status of animals, when known: SPF
- Age at study initiation: 5 weeks
- Weight at study initiation: 337–395 g
- Housing: (during the study) stainless wire mesh cages, 210W×350D×180H (mm), one animal per cage
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 12 days
- Indication of any skin lesions: no

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.0–23.8°C (permissible range: 18.0-24.0°C)
- Humidity (%): 33.9–52.1% (permissible range: 30.0-70.0%)
- Air changes (per hr):10–15 times/hour
- Photoperiod (hrs dark / hrs light):12 hour light/dark cycle

Study design: in vivo (non-LLNA)

Induction

Route:

intradermal and epicutaneous

Vehicle:

olive oil

Concentration / amount:

25% / 0.1 mL (intradermal), 100 % / 0.2 mL (topical application)

Day(s)/duration:

Day 0 Intradermal; Day 7 topical application for 48 h

Adequacy of induction:

non-irritant substance, but skin pre-treated with 10% SDS

Challenge

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

unchanged (no vehicle)

Concentration / amount:

100% / 0.1 mL

Day(s)/duration:

24 h

Adequacy of challenge:

highest non-irritant concentration

No. of animals per dose:

10 (5 for control)

Details on study design:

RANGE FINDING TESTS: Based on the results of the preliminary test the concentrations for the main study was determined

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (first induction: intradermal exposure; second induction: epicutaneous exposure)
- Exposure period: 20 days
- Test groups: 1
- Control group: 1
- Site: Six sites, three each on the left and right sides of the midline of the shoulder region for injection and two sites, one on the left and one on the right sidesfor application (region of the first induction sites)
- Frequency of applications: once
- Duration: 48 h
- Concentrations: 25%

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: Day 21
- Exposure period: 3 days
- Test groups: 1
- Control group: 1
- Site: two sites, one on the left (for test substance) and one on the right (for vehicle) sides (region of the induction sites)
- Concentrations: 100%
- Evaluation (hr after challenge): 24 and 48 hours

Positive control substance(s):

yes

Remarks:

CDNB (1-Chloro-2,4- dinitrobenzene)

Results and discussion

Positive control results:

The sensitization rate of CDNB was 100% and the sensitization grade was classified to be ‘V (Extreme)’ according to the classification of skin sensitization grade of Magnusson & Kligman. Consequently, the study was considered to be valid.

In vivo (non-LLNA)

Results

Results 1

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

100%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

no

Remarks on result:

no indication of skin sensitisation

Results 2

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

100%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

no

Remarks on result:

no indication of skin sensitisation

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The test item did not produce skin sensitization under the conditions of this study.

Executive summary:

A Guinea pig maximization test was performed (OECD 406). In the test substance group, the 25% test substance was injected intradermally for the first induction. The second induction was concluded with the 100% test substance occluded for 48 hours. The challenge was conducted with the 100% test substance and olive oil occluded for 24 hours. As a result, no skin reactions such as redness or swelling were observed in any animal at 24 and 48 hours after challenge patch removal. Based on the results, isoamyl isovalerate item did not produce skin sensitization under the conditions of this study.