[No public or meaningful name is available]

Endpoint summary

Description of key information

The key study for skin sensitisation for the submission substance, reports the test material not to be sensitising to skin. The study was conducted according to OECD TG 406 and in compliance with GLP (Safepharm, 1999).

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:

1999-01-04 to 1999-02-13

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

An LLNA study was not performed because there is an existing reliable study for skin sensitisation using the Guinea Pig Maximisation test method. Furthermore, the LLNA test method is not considered to be suitable for substances that contain silicon. Please refer to the attached document for further details.

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: David Hall Limited
- Age at study initiation: 8 - 12 weeks
- Weight at study initiation: 354 - 457 g
- Housing: housed singly or in pairs in solid-floor polypropylene cages
- Diet: guinea-pig FD1 diet, ad libitum
- Water: mains tap water, ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 - 22
- Humidity (%): 40 - 55 %
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Route:

epicutaneous, occlusive

Vehicle:

arachis oil

Concentration / amount:

TEST GROUP
Intradermal induction: 25% w/v in arachis oil BP
Topical induction: undiluted as supplied
Topical challenge: undiluted as supplied and 75% v/v in archis oil BP

NEGATIVE CONTROL:
Intradermal induction: Freund's Complete Adjuvant/distilled water 1:1; arachis oil BP; 50 % arachis oil BP in Freund's Complete Adjuvant/distilled water 1:1
Topical induction: blank patch applied
Topical challenge: 75% and 100% in arachis oil BP

POSITIVE CONTROL:
Intradermal induction: 10 % 2-mercaptobenzothiazole in arachis oil BP
Topical induction: 50 % in acetone PEG 400 (70:30)
Topical challenge: 25 % and 50 % in acetone PEG 400 (70:30)

Route:

epicutaneous, occlusive

Vehicle:

arachis oil

Concentration / amount:

TEST GROUP
Intradermal induction: 25% w/v in arachis oil BP
Topical induction: undiluted as supplied
Topical challenge: undiluted as supplied and 75% v/v in archis oil BP

NEGATIVE CONTROL:
Intradermal induction: Freund's Complete Adjuvant/distilled water 1:1; arachis oil BP; 50 % arachis oil BP in Freund's Complete Adjuvant/distilled water 1:1
Topical induction: blank patch applied
Topical challenge: 75% and 100% in arachis oil BP

POSITIVE CONTROL:
Intradermal induction: 10 % 2-mercaptobenzothiazole in arachis oil BP
Topical induction: 50 % in acetone PEG 400 (70:30)
Topical challenge: 25 % and 50 % in acetone PEG 400 (70:30)

No. of animals per dose:

Number of animals in test group: 10
Number of animals in negative control group: 5

Details on study design:

RANGE FINDING TESTS:
Selection of concentrations for intradermal injection: Solution of 1 %, 5 %, 10 % and 25 % (v/v) of test material in arachis oil BP was injected to 4 guinea-pigs. Each animal received four 0.1 ml injections of only one concentration. The degree of erythema was assessed at 24 h, 48 h, 72 h and 7 days. The degree of oedema was not assessed. The highest concentration that caused mild to moderate skin irritation and that was well-tolerated systematically was selected for the intradermal injection stage. Mild to moderate erythema was observed in all the animals at 24, 48, 72 hours and 7 days post-treatment. The selected concentration for intradermal injection was 25 % (w/v) in arachis oil BP.

Selection of concentration for topical induction: Two guinea-pigs were injected with Freund's Complete Adjuvant 16 days earlier. They were treated with undiluted test material as well as solutions of 25 %, 50 % and 75 % (v/v) of the test material in arachis oil BP. The test material was applied for 48 h under occlusive dressing and the degree of erythema and oedema was evaluated at 1 h, 24 h, 48 h after dressing removal. The highest concentration producing mild to moderate irritation reaction was selected for the topical induction stage. The results showed that the test material was not irritating and undiluted test material was selected for the topical induction stage of the main study.

Selection of concentration for topical challenge: The test material was applied undiluted and in solutions of 25 %, 50 % and 75 % in arachis oil BP to clipped skin of two guinea-pigs for 24 h under occlusive dressing. The degree of erythema and oedema was evaluated at 1 h, 24 h and 48 h after dressing removal. The highest non-irritant concentration and one lower were selected for the topical challenge stage. Slight erythema was observed at 1 hour post-treatment. There were no other clinical changes at 1, 24 and 48 hours observations. Undiluted test material and 75 % (v/v) in arachis oil BP were the selected concentrations for the challenge stage of the main study.

MAIN STUDY
A test group of 10 guinea-pigs and a control group of 5 guinea-pigs were used in the study. The body weight of each animal was recorded at the start and the end of the study.

A. INDUCTION EXPOSURE
Test group: The shoulder region of all the test animals was clipped and 3 injections (0.1 ml) were administered on each side of the mid-line. Injection 1 - Freund's Complete Adjuvant plus distilled water in the ratio 1:1; injection 2 - 25 % (w/v) of the test material in arachis oil BP, injection 3 - 25 % (w/v) of the test material in 1:1 preparation of Freund's Complete Adjuvant plus distilled water. The degree of erythema was evaluated at 24 h and 48 h post-injection using Draize score system. On day 7 of the study period, the same area was clipped and shaved. The undiluted test material was applied to the test area and kept under occlusive dressing for 48 hours. The degree of erythema and oedema was evaluated at 1 and 24 hours after removal of the dressing. Other reactions were also recorded.

Control group: Three intradermal injections were administered to the control animals. Injection 1 - Freund's Comlete Adjuvant plus distilled water in ration 1:1. Injection 2 - arachis oil BP. Injection 3 - 50 % solution of arachis oil BP in Freund's Complete Adjuvant plus distilled water in ration 1:1. The degree of erythema and oedema was evaluated according to Draize score at 24 and 48 hours post-injections. The test material was kept for 48 hours under an occlusive dressing.

B. CHALLENGE EXPOSURE
Test and control group: On day 21 the right and left shorn flank of each animal were clipped and shaved. The unsaturated test material was applied onto the right shorn flank under an occlusive dressing for 24 hours. A solution of 75 % (v/v) test material in arachis oil BP was applied to the left shorn flank under occlusive dressing, kept for 24 hours. After removal of both patches, the test sites were swabbed with diethyl ether to remove residual material. The degree of erythema and oedema was evaluated using Draize scale at 24 and 48 hours after removal of the dressing.

Challenge controls:

A 75% and 100% application of test material on control animals, resulted in no erythema or oedema and no other reactions were noted.

Positive control substance(s):

yes

Remarks:

2-mercaptobenzothiazole

Positive control results:

The historical positive control data records show appropriate positive control reactions, ranging from 70-100% of the test animals being sensitised.

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

100%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

None

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

100%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

None

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

75%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

None

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

75%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

None

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

100%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

None

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

100%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

None

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

75%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

None

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

75%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

None

Key result

Reading:

other: Historical positive control data

Group:

positive control

Remarks on result:

positive indication of skin sensitisation

Remarks:

Historical positive control data were reported in Appendix XI of the study report. Appropriate incidence of sensitisation was reported for 2-mercaptobenzothiazole and 2,4,-dinitrochlorobenzene.

Signs of irritation during induction:
Skin Reactions Observed After Intradermal Induction:
Test group: Well-defined moderate to severe erythema was noted at the intradermal induction sites of all test group animals at the 24-hour observation with very slight to moderate to severe erythema at the 48-hour observation.
Control group: Very slight to well-defined erythema was noted at the intradermal induction sites of all control group animals at the 24-hour observation with very slight erythema at the 48-hour observation.

Skin Reactions Observed After Topical Induction:

Test group: Hardened, adhered test material, which precluded the accurate evaluation of erythema, was noted at the topical induction sites of four test group animals with residual test material at the topical induction sites of three other test group animals at the 1-hour observation. Slight yellow-coloured staining was noted at the topical induction sites of three test group animals at the 24-hour observation.

Very slight to well-defined erythema was noted at the topical induction sites of six test group animals at the 1-hour observation. Very slight to slight oedema was noted at the topical induction sites of all test group animals at the 1-hour observation. Very slight erythema with or without very slight oedema was noted at the topical induction sites of nine test group animals at the 24-hour observation.

Other skin reactions noted at the topical induction sites of test group animals at the 1-hour observation were desquamation and bleeding from the intradermal injection sites of the two test group animals at the 24-hour observation.

Control group: Very slight to well-defined erythema with or without very slight oedema was noted at the topical induction sites of all control group animals at the 1-hour observation. Very slight erythema was noted at the topical induction sites of four control group animals at the 24-hour observation.

Other skin reactions noted at the topical induction sites of control group animals at the 1-hour observation were desquamation and bleeding from the intradermal injection sites. Dried blood was noted at the intradermal injection sites of two control group animals at the 24-hour observation.

Evidence of sensitisation of each challenge concentration: Number of animals showing evidence of sensitisation at each
challenge concentration: 0/10

Gain in body weight was observed in both the test and control groups.

Interpretation of results:

GHS criteria not met

Conclusions:

The test substance was found not to be sensitising to skin, in Guinea Pig Maximisation Test, conducted according to OECD TG 406 and in compliance with GLP.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The key study for skin sensitisation for the submission substance, reports the test material not to be sensitising to skin. The study was conducted according to OECD TG 406 and in compliance with GLP (Safepharm, 1999).

Following an intradermal induction of 25% (w/v) test material in arachis oil BP into guinea-pigs, moderate to severe erythema was observed at 24 hours post-injection in all of the 10 treated animals. Slight erythema was observed at 48 hours post-injection in all the test animals. The same effect was observed at 24 hours and 48 hours post-injection in all the 5 control animals.

Following topical induction with undiluted test material onto guinea-pig skin, well-defined to slight erythema was observed in 6 out of 10 of the treated animals at 1 hour post-treatment. Slight signs of oedema were noted in all the treated guinea-pigs at 1 hour observation. Slight erythema was observed at 24 hours post-treatment in 9 of the treated animals. Slight erythema with or without sings of oedema was observed at 1 hour and 24 hours post-treatment in all the 5 control animals.

At challenge, the test material was administered undiluted and at 75 % (v/v) in arachis oil BP, as a topcial occlusive application to guinea-pigs. Following treatment with both the undiluted application and 75% (v/v) test material, no signs of erythema or oedema were observed in any of the 10 treated animals at 24 hours and 48 hours post-treatment.

The negative and positive control animals, all demonstrated appropriate reactions.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the available information for the submission substance, no classification is required for skin sensitisation, in accordance with Regulation (EC) No. 1272/2008.