4-[(1-butyl-5-cyano-1,6-dihydro-2-hydroxy-4-methyl-6-oxo-3-pyridyl)azo]-N-(2-ethylhexyl)benzenesulphonamide

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20 May 1999 - 24 June 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-compliant guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

GLP compliance:

yes

Type of study:

Buehler test

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: D. Hall, Newchurch, Staffordshire, England
- Age at study initiation: four to seven weeks
- Weight at study initiation: 365 - 428 g
- Housing: in groups of five in suspended metal cages with wire mesh floors
- Diet: vitamin C enriched guinea-pig diet (Harlan Teklad 9600 FD2 SQC), ad libitum
- Water: drinking water, ad libitum
- Acclimation period: five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17.5 to 28.0°C
- Humidity (%): 37 to 64%
- Photoperiod (hrs dark / hrs light): 12/12

Route:

epicutaneous, occlusive

Vehicle:

other: Alembicol D (A product of coconut oil, supplied by Alembic Products)

Concentration / amount:

Based on the results of the preliminary investigations, the following concentrations were selected:
Induction topical application - 55% w/v in Alembicol D
Topical challenge - 55% w/v in Alembicol D

Route:

epicutaneous, occlusive

Vehicle:

other: Alembicol D (A product of coconut oil, supplied by Alembic Products)

Concentration / amount:

Based on the results of the preliminary investigations, the following concentrations were selected:
Induction topical application - 55% w/v in Alembicol D
Topical challenge - 55% w/v in Alembicol D

No. of animals per dose:

For the main test, twenty test and ten control animals were used. An additional four animals from the same supplier were used for the preliminary investigations.

Details on study design:

RANGE FINDING TESTS:
The topical irritancy of a range of dilutions of the test substance was investigated to identify where possible (a) concentrations of the test substance that would produce irritation suitable for the induction phase of the main study and (b) a maximum non-irritant concentration for the challenge phase. Approximately 0.5 ml of a range of concentrations (10 to 55% w/v) in a suitable vehicle (Alembicol D) was applied to patches of surgical gauze (20 x 20 mm). These were placed occlusively on the clipped and shaved flanks of each of four guinea-pigs. After an exposure period of approximately six hours the dressings were removed and the reaction sites were assessed for erythema and oedema. Further examination of the sites was carried out approximately 24 and 48 hours after removal of the dressings.

MAIN STUDY
A. INDUCTION EXPOSURE
Prior to each induction application, the skin on the left shoulder region of the guinea-pig was clipped free of hair using electric clippers. A 20 x 20 mm patch of surgical gauze (three layers thick) was saturated with approximately 0.5 ml of the test article 55% w/v in Alembicol D. The patch was placed on the skin and covered by a length of impermeable plastic adhesive tape (50 mm width "Blenderm"). This in turn was firmly secured by elastic adhesive bandage (50 mm width "Elastoplast") wound round the torso of the animals and fixed with "Sleek" impervious plastic adhesive tape. Contact with the skin was maintained for approximately 6 hours for each induction exposure. The dressings were then removed and the resulting dermal reactions assessed approximately 24 hours later. One induction application was made in this manner on Days 1, 8 and 15 so a total of three induction applications were made.
During the induction phase, the control animals were treated similarly to the test animals with the exception that the test substance was omitted from the induction applications.

B. CHALLENGE EXPOSURE
The control and test animals were challenged topically two weeks after the final induction application using the test article, 55% w/v in Alembicol D. Hair was removed by clipping and then shaving from a 50 x 50 mm area on the right flank of each guinea-pig. A 20 x 20 mm surgical gauze patch was saturated with approximately 0.5 ml of the test substance, 55% w/v in Alembicol D and applied to the flank in a similar manner to the induction applications. The patches were sealed to the flank under strips of "Blenderm" covered by "Elastoplast" wound round the trunk and secured with "Sleek". Dressings were left in place for approximately 6 hours after which time they were removed.

Positive control substance(s):

yes

Remarks:

The sensitivity of the guinea-pig strain used is checked periodically at Huntingdon Life Sciences with known sensitisers hexyl cinnamic aldehyde (HCA) or 2-mercaptobenzothiazole (MBT).

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

55%

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 55%. No with. + reactions: 0.0. Total no. in groups: 20.0.

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

55%

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 55%. No with. + reactions: 0.0. Total no. in groups: 20.0.

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

55%

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 55%. No with. + reactions: 0.0. Total no. in groups: 10.0.

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

55%

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 55%. No with. + reactions: 0.0. Total no. in groups: 10.0.

CLINICAL SIGNS

No signs of ill health or toxicity were observed.

BODYWEIGHT

Bodyweight increases were recorded for all guinea-pigs over the period of the study.

INDUCTION

There were no dermal reactions seen in any of the test or control animals.

CHALLENGE

There were no dermal reactions seen in any of the test or control animals, therefore all twenty test animals gave negative responses.

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The test article did not produce evidence of skin sensitization (delayed contact hypersensitivity) in any of the twenty test animals.

Executive summary:

A Buehler Test following OECD guideline 406 was performed to assess the skin sensitization potential of the test article using the guinea-pig. Based on the results of a preliminary study and in compliance with the guidelines, the following dose levels were selected: Topical application: 55% w/v in Alembicol D; Challenge application: 55% w/v in Alembicol D. Twenty test and ten control guinea-pigs were used in this study. In this study the test article did not produce evidence of skin sensitization (delayed contact hypersensitivity) in any of the twenty test animals.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

A GLP-compliant Buehler Test following OECD guideline 406 was performed to assess the skin sensitization potential of the test article using the guinea-pig. Based on the results of a preliminary study and in compliance with the guidelines, the following dose levels were selected: Topical application: 55% w/v in Alembicol D; Challenge application: 55% w/v in Alembicol D. Twenty test and ten control guinea-pigs were used in this study. Topical induction applications on the clipped shoulder were performed on days 1, 8 and 15. Two weeks after the final induction a challenge application was performed. In this study the test article did not produce evidence of skin sensitization (delayed contact hypersensitivity) in any of the twenty test animals.

Migrated from Short description of key information:
The test article did not cause sensitizing effects in a Buehler study using guinea pigs.

Justification for selection of skin sensitisation endpoint:
GLP-compliant guideline study