4-chloro-7H-pyrrolo[2,3-d]pyrimidine

Endpoint summary

Description of key information

The LLNA study was performed on the test item according to OECD Guideline 442B under GLP.

Topical application of test article at 10%, 25%, and 50% (w/v) in DMSO resulted in SI values greater than 1.6. Therefore, this test article is a dermal sensitizer in the Local Lymph Node Assay.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 20 Dec 2016 to 19 Jan 2017

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 442B (Skin Sensitization: Local Lymph Node Assay: BrdU-ELISA)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA): BrdU-ELISA

Species:

mouse

Strain:

CBA:J

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Jackson Laboratories (Bar Harbor, ME) on 07 Dec 2016.
- Females (if applicable) nulliparous and non-pregnant: yes
- Microbiological status of animals, when known:
- Age at study initiation: The animals were born on 18 Oct 2016, ± 3 days.
- Weight at study initiation: The Day 1 body weight range for the preliminary dermal irritation screen animals was 18.7 - 20.8 grams. The Day 1 body weight range for the main test animals was 20.6 - 24.5 grams.
- Housing: During the acclimation period the animals were housed two per cage in suspended wire-bottom cages; during the study the animals were housed one per cage. Bedding was placed beneath the cages and changed at least three times per week.
- Diet (e.g. ad libitum): Fresh PMI Rodent Chow (Diet No. 5001) were available ad libitum.
- Water (e.g. ad libitum): Water were available ad libitum.
- Acclimation period: at least five days
- Indication of any skin lesions: The animals were observed prior to the study start to ensure that
no skin lesions were present on the ears.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): temperature-controlled
- Humidity (%):
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light): 12-hour light/dark cycle

Vehicle:

dimethyl sulphoxide

Concentration:

10%, 25% and 50% [w/v]

No. of animals per dose:

5 females

Details on study design:

PRE-SCREEN TESTS:
- Compound solubility: The test article was found to be soluble in DMSO, with approximately 30 minutes of sonication.
- Irritation: no
- Systemic toxicity: no
- Ear thickness measurements: Ear thickness measurements were performed on Day 1 prior to dosing, on Day 3 before the third test article application, and on Day 6 before euthanasia. None of the test article treatments resulted in increases in ear thickness of 25% or more, and therefore the test article was not considered irritating.
- Erythema scores: No test article treatment produced erythema.

MAIN STUDY
The test article concentrations used in the main LLNA study were chosen such that the
maximum concentration tested was the highest achievable solution of the test article in the vehicle, while avoiding both overt systemic toxicity and excessive local dermal irritation. Concentrations of 10%, 25% and 50% (w/v) were chosen.

ANIMAL ASSIGNMENT AND TREATMENT
- Criteria used to consider a positive response: A test article is considered to have a positive response if treatment results in a 1.6-fold or greater increase in the mean LNC proliferation (BrdU ELISA OD values) relative to that obtained for the vehicle control. Therefore, test articles that yield an SI value of 1.6 or more are characterized as potential sensitizing articles.

TREATMENT PREPARATION AND ADMINISTRATION: Treatment was made by topical application of the test article concentrations to the dorsum of each ear once daily for three consecutive days. The test article was spread over the entire dorsal surface of the ear using a micropipette to deliver 25 μl/ear.

Positive control substance(s):

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

Statistics:

Statistical evaluation of the calculated SI values was made by ANOVA followed by the Student's t-test.

Key result

Parameter:

SI

Value:

1.2

Test group / Remarks:

10% w/v

Key result

Parameter:

SI

Value:

1.9

Test group / Remarks:

25% w/v

Key result

Parameter:

SI

Value:

3.3

Test group / Remarks:

50% w/v

Cellular proliferation data / Observations:

Mortality and Systemic Observations:
All animals survived the in-life phase of the study.
Body Weights:
Body weight changes were normal.
Erythema Scores:
No test article treatment produced erythema. The 25% HCA positive control produced no more than very slight erythema.
Ear Thickness as a Measure of Dermal Irritation:
In the main test, none of the test item concentrations tested resulted in excessive dermal irritation.

Interpretation of results:

Category 1B (indication of skin sensitising potential) based on GHS criteria

Conclusions:

Topical application of test article at 10%, 25%, and 50% (w/v) in DMSO resulted in SI values greater than 1.6. Therefore, this test article is a dermal sensitizer in the Local Lymph Node Assay.

Executive summary:

The LLNA study was performed on the test item according to OECD Guideline 442B under GLP.

Topical application of test article at 10%, 25%, and 50% (w/v) in DMSO resulted in SI values greater than 1.6. Therefore, this test article is a dermal sensitizer in the Local Lymph Node Assay.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Skin sensitisation:
LLNA study give positive result with SI value of greater than 1.6.
According to Regulation (EC) No 1272/2008, table 3.4.2, this substance should be classified as Category 1B for this endpoint.