3-[[4-[(2-chloro-4-nitrophenyl)azo]phenyl]ethylamino]propiononitrile

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

other: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

From June 2 to July 5, 1999

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Source study has reliability 1. Details on the read across are available in section 13.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

not specified

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Deviations:

not specified

GLP compliance:

yes

Type of study:

Buehler test

Justification for non-LLNA method:

A LLNA study was not conducted because adequate data from a Buehler test was already available.

Test material

Test material information

Constituent 1

Reference substance name:

Similar Substance 01 - DsR050

IUPAC Name:

Similar Substance 01 - DsR050

In vivo test system

Test animals

Species:

guinea pig

Strain:

other: Ibm: GOHI; SPF-quality guinea pigs (synonym: Himalayan spotted)

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: RCC Ltd, Biotechnology & Animal Breeding Division, Wolferstrasse 4, CH-4414 Füllinsdorf / Switzerland
- Females nulliparous and non-pregnant: yes
- No. of animals for irritation screen: 4 F
- No. of animals for main study: 30 F; challenge: 20 test animals and 10 control animals
- Age at study initiation: 4 - 6 weeks
- Weight at study initiation: 301 - 400 g
- Housing: individually in Makroion type-4 cages with standard softwood bedding ("Lignocel", Schill AG, CH-4132 Muttenz).
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 1 week for control and test group under test conditions after health examination. However, contrary to test group, control group remained untreated during the 3 induction weeks. One day for animals used in the irritation screen for induction and challenge.
- Indication of any skin lesions: only animals without any visible signs of illness were used for the study.

ENVIRONMENTAL CONDITIONS
- Temperature: 22 ± 3 °C
- Humidity: 40 - 70 %
- Air changes: 10 - 15 per h
- Photoperiod: 12 hr dark / 12 hr light

Study design: in vivo (non-LLNA)

Induction

Route:

epicutaneous, occlusive

Vehicle:

water

Concentration / amount:

induction: 50 %
challenge: 50 %

Challenge

Route:

epicutaneous, occlusive

Vehicle:

water

Concentration / amount:

induction: 50 %
challenge: 50 %

No. of animals per dose:

Challenge:
- 20 test animals
- 10 control animals
Irritation screen:
- 4 animals

Details on study design:

IRRITATION SCREEN FOR INDUCTION AND CHALLENGE - PERF
Four guinea pigs were used. Four different concentrations were used on each animal for a 6-hour exposure period. Test article concentration of 50 % in bi-distilled water was considered to be the most qualified to assure an optimum technical application procedure.
The allocation of the different test dilutions to the sites (A, B, C, D) on the four animals was alternated in order to minimize site-to-site variation in responsiveness. Application sites were assessed for erythema and oedema 24 and approximately 48 hours after removal of the patches.
The highest test article concentration of 50 % in bi-distilled water was considered to be the most representative concentration to stimulate a state of immune hypersensitivity in the induction phase and the highest non-irritating concentration to be used for the challenge.

INDUCTION
Concentration of test article required for induction was agreed after the irritation screen had been completed. The fur was clipped from the left shoulder of each test animal and patches applied, over a period of 3 weeks. Each animal received one patch per week which remained in place for approximately 6 hours each. Repeated application was performed at the same site. Interval between exposure was one week. After the last induction exposure, animals were left untreated for 2 weeks before the challenge.
Skin responses were graded approximately 24 hours after patches have been removed. Any gross skin reactions were recorded without depilation.

CHALLENGE - PERFORMED ON TEST DAY 29
Animals previously exposed during the induction period (i.e. test group) as well as the previously untreated control animals were challenged two weeks after last induction exposure using the dose as prescribed. Fur was clipped from the left posterior quadrant of the side and back of the animals. Exposure period was 6 hours on a naive skin site. Responses were graded at 24 and 48 h after patches have been removed.

Positive control substance(s):

yes

Remarks:

alpha-hexylcinnamaldehyde

Results and discussion

Positive control results:

90 % of the animals of the test group were observed with significant skin reactions (grade of 0 and ± are considered to be non-significant responses, whereas those of 1 and greater are considered to be significant) after challenge performed with the highest nonirritating concentration of alpha-hexylcinnamaldehyde at 10 % in PEG 400.
No skin reactions were observed in the control group treated in the same conditions during the challenge phase.
Therefore, positive control applied at a concentration of 10 % in PEG 400 is considered to be a sensitizer when used under the described test conditions.

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

50 %

No. with + reactions:

8

Total no. in group:

20

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

50 %

No. with + reactions:

4

Total no. in group:

20

Any other information on results incl. tables

VIABILITY / MORTALITY / MACROSCOPIC FINDINGS

There were no deaths during the course of the study, hence no necropsies were performed.

CLINICAL SIGNS, SYSTEMIC

No symptoms of systemic toxicity were observed in the animals.

SKIN EFFECT IN THE INDUCTION

As test article at 50 % in bi-distilled water stained the skin violet, it was not possible to determine whether erythema was present or not. However, no oedema was observed.

SKIN EFFECT IN THE CHALLENGE

Discrete/patchy erythema was observed in 8 (at the 24 -hour reading) and 4 (at the 48 - hour reading) out of 20 test animals after treatment with test article at 50 % in bi-distilled water. No skin reactions were observed in animals of the control group treated with same test article, vehicle and concentration.

BODY WEIGHTS

The body weight of animals was within the range commonly recorded for animals of this strain and age.

Applicant's summary and conclusion

Interpretation of results:

other: classified as Category 1B (indication of skin sensitising potential) based on CLP Regulation (EC 1272/2008)

Conclusions:

Skin sensitising.

Executive summary:

Method

The skin sensitising potential of test substance was evaluated using a Buheler test, according to the OECD guideline 406.

Results

20 female animals of test group were treated topically with test substance at 50 % in bi-distilled water once a week for a 3 week induction phase. 2 weeks after the final induction application, animals were challenged with the same test article concentration of 50 % in bi-distilled water as used for induction. The 10 animals of the control group were not treated during the induction but were treated once at challenge with test substance at 50 % in bi-distilled water.

In this study, 40 % of animals in test group showed skin reactions after challenge treatment performed with the highest non-irritant concentration of test substance at 50 % in bi-distilled water. No skin reactions were observed in the control group treated in the same conditions during the challenge phase.

Under experimental conditions, the substance is considered as a skin sensitizer.