1,2-dihydro-3H-1,2,4-triazol-3-one

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

01 Aug 2018 - 22 Aug 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

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:

triazol-4-one

Cas Number:

930-33-6

Molecular formula:

C2H3N3O

IUPAC Name:

triazol-4-one

Test material form:

solid: crystalline

Specific details on test material used for the study:

Batch: 0727/16
Purity: 99%

In vivo test system

Test animals

Species:

mouse

Strain:

CBA/Ca

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Envigo RMS (UK) Limited
- Females: nulliparous and non-pregnant
- Age at study initiation: 8 to 12 weeks old
- Weight at study initiation: 15 to 23 g
- Housing: randomly allocated to cages
- Diet (e.g. ad libitum): Free access to food
- Water (e.g. ad libitum): Free access to mains tap water
- Acclimation period: at least 5 days
- Indication of any skin lesions: none

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 25°C
- Humidity (%): 30 to 70%
- Air changes (per hr): at least fifteen changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours continuous light and 12 hours darkness

Study design: in vivo (LLNA)

Vehicle:

dimethyl sulphoxide

No. of animals per dose:

4

Details on study design:

PRE-SCREEN TESTS:
- Compound solubility: freshly prepared as a solution in dimethyl sulfoxide. This vehicle was chosen as it produced the highest concentration that was suitable for dosing.
- Using available information regarding the systemic toxicity/irritancy potential of the test item, a preliminary screening test was performed using one mouse. The mouse was treated by daily application of 25 µL of the test item at a maximum attainable concentration of 10% w/w in dimethyl sulfoxide, to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The mouse was observed twice daily on Days 1, 2 and 3 and once daily on Days 4, 5 and 6. Local skin irritation was scored daily.
Any clinical signs of toxicity, if present, were also recorded. The body weight of the mouse was recorded on Day 1 (prior to dosing) and on Day 6.
The thickness of each ear was measured using a Mitutoyo 547 300S gauge (Mitutoyo Corporation), pre dose on Day 1, post dose on Day 3 and on Day 6. A mean ear thickness increase of equal to or greater than 25% was considered to indicate excessive irritation and limited biological relevance to the endpoint of sensitization.

MAIN STUDY

TREATMENT PREPARATION AND ADMINISTRATION:
Groups of four mice were treated with the test item at concentrations of 2.5%, 5% or 10% w/w in dimethyl sulfoxide. The preliminary screening test suggested that the test item would not produce systemic toxicity or excessive local skin irritation at the highest suitable concentration. The mice were treated by daily application of 25 µL of the appropriate concentration of the test item to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The test item formulation was administered using an automatic micropipette and spread over the dorsal surface of the ear using the tip of the pipette.
A further group of four mice received the vehicle alone in the same manner.

- Criteria used to consider a positive response: Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group

Positive control substance(s):

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

Statistics:

not specified

Results and discussion

Positive control results:

The Stimulation Index expressed as the mean radioactive incorporation for the treatment group divided by the mean radioactive incorporation of the vehicle control group is as follows:

Concentration (% v/v) in dimethyl sulphoxide = 25
Stimulation index = 8.47
Result = Positive

α Hexylcinnamaldehyde, tech., 85% was considered to be a sensitizer under the conditions of the test.

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Remarks:

2.5% w/w

Value:

0.5

Test group / Remarks:

Negative

Results 2

Key result

Parameter:

SI

Remarks:

5% w/w

Value:

0.82

Test group / Remarks:

Negative

Results 3

Key result

Parameter:

SI

Remarks:

10% w/w

Value:

0.57

Test group / Remarks:

Negative

Cellular proliferation data / Observations:

CLINICAL OBSERVATIONS: There were no deaths. No signs of systemic toxicity were noted in the test or control animals during the test.

BODY WEIGHTS: Body weight change of the test animals between Day 1 and Day 6 was comparable to that observed in the corresponding control group animals over the same period.

Any other information on results incl. tables

Table 1. Results from main test (stimulation index)

Concentration (%w/w) in dimethyl sulfoxide	Stimulation Index	Result
2.5	0.50	Negative
5	0.82	Negative
10	0.57	Negative

The Stimulation Index is expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The test item was considered to be a non-sensitizer under the conditions of the test.