Trisilicon tetranitride

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 13 to 19 June 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study run to a method comparable with current guidelines and to GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

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:

Trisilicon tetranitride

EC Number:

234-796-8

EC Name:

Trisilicon tetranitride

Cas Number:

12033-89-5

Molecular formula:

N4Si3

IUPAC Name:

1Si-hexacyclo[3.1.1.0¹,⁴.0²,⁵.0³,⁶.0³,⁷]trisilazane

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

Batch No.: A126325
Purity: >98%

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/Ca

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Age at study initiation: approximately eight to twelve weeks
- Weight at study initiation: 17.4 to 20.9 g
- Housing: Animals were housed inside a barriered rodent facility (Building F21, Room 061/062).
- Diet (e.g. ad libitum): The animals were allowed free access to a standard rodent diet (Rat and Mouse No. 1 Maintenance Diet).
- Water (e.g. ad libitum): Potable water taken from the public supply was freely available via polycarbonate bottles fitted with sipper tubes.
- Acclimation period: at least 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 23°C
- Humidity (%): 40 to 70%
- Photoperiod (hrs dark / hrs light): a cycle of 12 hours continuous light and 12 hours continuous dark per 24 hours

IN-LIFE DATES: From: 13 June 2013 To: 18 June 2013

Study design: in vivo (LLNA)

Vehicle:

dimethylformamide

Concentration:

10, 25 and 50% w/v in dimethylformamide

No. of animals per dose:

4

Details on study design:

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: LLNA
- Criteria used to consider a positive response: The test substance is regarded as a sensitizer if at least one concentration of the chemical has a Stimulation Index (SI) of three or more.

TREATMENT PREPARATION AND ADMINISTRATION:
Groups of four mice were treated at one of three concentrations of the test substance. The mice were treated by daily application of 25 μL of the appropriate concentration of the test substance to the dorsal surface of each ear for three consecutive days (Days 1-3). The test substance was applied to the dorsal surface of each ear using an automatic micropipette and was spread over the entire dorsal surface of the ear using the tip of the pipette. Further groups of four mice received the vehicle alone or the positive control substance in the same manner.
Five days following the first topical application of test substance (Day 6) all mice were injected via the tail vein with 250 μL of phosphate buffered saline containing 3H-methyl Thymidine (3HTdR: 80 μCi/mL) giving a nominal 20 μCi to each mouse. The injection into the tail vein was carried out using a plastic syringe and needle after the mouse had been heated in a warming chamber.

Positive control substance(s):

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

Statistics:

None stated

Results and discussion

Positive control results:

The SI for the positive control substance hexyl cinnamic aldehyde (HCA), was 4.8 which demonstrates the validity of this study.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

1.5

Test group / Remarks:

4

Remarks on result:

other: The SI (test/control ratios) obtained for 10, 25 and 50% w/v test substance were 0.8, 1.2 and 1.5 respectively. As a SI of 3 or more was not recorded for any of the concentrations tested, the test substance is not considered to have the potential to cause

Results 2

Parameter:

SI

Value:

1.2

Test group / Remarks:

3

Remarks on result:

other: The SI (test/control ratios) obtained for 10, 25 and 50% w/v test substance were 0.8, 1.2 and 1.5 respectively. As a SI of 3 or more was not recorded for any of the concentrations tested, the test substance is not considered to have the potential to cause

Results 3

Parameter:

SI

Value:

0.8

Test group / Remarks:

2

Remarks on result:

other: see Remark

Remarks:

The SI (test/control ratios) obtained for 10, 25 and 50% w/v test substance were 0.8, 1.2 and 1.5 respectively. As a SI of 3 or more was not recorded for any of the concentrations tested, the test substance is not considered to have the potential to cause skin sensitization.

Results 4

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: The DPM for the 10% w/v, 25% w/v and 50% w/v is 7584.00, 13279.50 and 16457.10 respectively.

Any other information on results incl. tables

Mortality and clinical signs

There were no deaths and no signs of ill health or toxicity were observed during this study.

Wet/greasy fur on the head was noted following each dosing occasion, this was related to unoccluded dermal administration of a liquid formulation/vehicle and not an effect of the test substance. White dose residue was seen in all test groups from after dosing on Day 1. These findings were no longer present on Day 6.

Dermal reactions

No signs of dermal irritation were seen on the ear during the study.

Bodyweight

There was no indication of an effect of treatment on bodyweight gain.

Group dpm/node and Stimulation Index

Group	Concentration	dpm	Number of lymph nodes per group	dpm/node	Stimulation Index†	Result + = positive - = negative
1 2 3 4 5	DMF 10% w/v 25% w/v 50% w/v HCA 25% v/v	11099.20 7584.00 13279.50 16457.10 53735.00	8.0 7.0 8.0 8.0 8.0	1387.40 1083.43 1659.94 2057.14 6716.88	n/a 0.8 1.2 1.5 4.8	n/a - - - +

† Stimulation Index of 3 or more indicates a positive result

n/a Not applicable

dpm Disintegrations per minute (less background count of 45.70 dpm)

DMF Dimethylformamide (vehicle control)

HCA Hexyl cinnamic aldehyde (positive control)

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

The test substance is not regarded as a potential skin sensitizer.