2,2,3-trimethylcyclopent-3-enylacetonitrile

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-05-11 to 2015-06-17

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to OECD Guideline and GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2010

Deviations:

no

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

2,2,3-trimethylcyclopent-3-enylacetonitrile

EC Number:

239-405-4

EC Name:

2,2,3-trimethylcyclopent-3-enylacetonitrile

Cas Number:

15373-31-6

Molecular formula:

C10H15N

IUPAC Name:

2-(2,2,3-trimethylcyclopent-3-en-1-yl)acetonitrile

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/Jcr

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Sprague-Dawley; Indianapolis, IN
- Age at study initiation: 8.5 weeks (Date Born: 10 Apr 15)
- Weight at study initiation: 19.2-23.2 g
- Housing: 1-5 per cage, Polycarbonate boxes with bedding
- Diet: ad libitum, PMI Feeds Inc.™ Formulab #5008
- Water: ad libitum, Municipal water supply analyzed by TCEQ Water Utilities Division
- Acclimation period: 5 days quarantine

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22-28
- Humidity (%): 49-91
- Air changes (per hr): 10+
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

25, 50 and 100 %

No. of animals per dose:

5 (female)

Details on study design:

RANGE FINDING TESTS: was not conducted

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: open application
- Criteria used to consider a positive response: EC3

TREATMENT PREPARATION AND ADMINISTRATION:
Five females were selected for each of three Test groups (Groups I - III). On Days 1, 2 and 3, each Test animal in its group received an open application of 25 µL of appropriate dilution (25 or 50 %) of test item in 4:1 v/v acetone:olive oil vehicle, or 100 % test item, to the dorsum of both ears. The Vehicle Control group (5 females) was treated the same way as test animals, but with vehicle alone instead of test item. The Positive Control group (5 females) was treated with 100 % alpha-hexylcinnamaldehyde. All Test and Control animals were given a two-day rest period on Days 4 and 5.
On Day 6 of the study, all Test and Control animals were injected in the tail vein with 250 µL of 0.01 M phosphate-buffered saline (PBS; Sigma, Lot SLBJ110V, Exp Jun 2024), pH 7.4 at 25°C per manufacturer, containing 20 µCi of [methyl-3H] Thymidine (PerkinElmer, Lot 201408, Exp Aug 2015). Five hours after injection, animals were sacrificed with an overdose of CO2, the draining auricular lymph nodes excised and pairs from each individual animal processed.

Observations
Individual body weights were recorded on Day 1 prior to dosing, and Day 6. prior to injection. All Test and Control animals were observed daily for clinical signs of toxicity and any signs of excessive irritation at the test site.

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 the DPM counts. If the test groups showed a stimulation index (SI) of > 3, then the extrapolated EC3 (estimated concentration required for a 3-fold stimulation index value) was calculated from the stimulation index values at 25% and either the 50% or 100% concentration and the substance was assessed as a weak, moderate- strong or extreme sensitizer.

Results and discussion

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: Please refer to "Any other information on results".

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: Please refer to "Any other information on results".

Any other information on results incl. tables

Body weight

One animal in each of Test Groups I and II lost weight during the study.

Clinical signs

All animals appeared normal for the duration of the study.

Stimulation Index or Test/Vehicle Control Ratio derived for each Test group based on group mean DPM:

Animal Group	Test Item Concentration [%]	Average DPM Count per Mouse	Number of Mice in Group	Test/Vehicle Control Ratio (Stimulation Index)
Vehicle Control	NA	534	5	NA
Test Group I	25	599	5	1.1
Test Group II	50	579	5	1.1
Test Group III	100	814	5	1.5
Positive Control	NA	2490	5	4.7*

NA - Not applicable

* - Positive Control used to confirm animal sensitization potential and validate procedures

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The test substance induced a stimulation index of < 3 in all test groups. Therefore it was considered to be not sensitising.

Executive summary:

A skin sensitization study was conducted on 3 groups of 5 female mice to determine if test item Cantryl possessed a significant potential to cause skin sensitization. Five females were assigned to each of three groups, designated Groups I - III. Test groups were treated with an appropriate dilution (25 or 50 %) in 4:1 v/v acetone:olive oil, or 100 % test item. Each animal received 25 µL to the dorsum of each ear. Animals were treated once daily for three days. After a two-day rest period, all animals were injected with tritiated methyl-thymidine in the tail vein. Five hours later, animals were sacrificed, and the draining auricular lymph nodes removed and prepared for cell suspension and scintillation counting. A Vehicle Control group of five females was run concurrently, treated in the same manner with vehicle only instead of test item or dilution. A Positive Control group of five females was also run concurrently, treated with 100 % alpha-hexylcinnamaldehyde.

The test item produced a stimulation index < 3 in all groups of test animals, and therefore was not a senitizer.