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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2004
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP and appropriate guidelines

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2004
Report Date:
2004

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
GLP compliance:
yes (incl. certificate)
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
study was done before requirements were known

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
White crystalline solid
Storage conditions : room temperature in the dark
Purity : 99.34%

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male
Details on test animals and environmental conditions:
Weight range of 300 to 450g, eight to twelve weeks old.
The animals were housed singly or in pairs in solid-floor polypropylene cages furnished with
woodflakes with free access to mains tap water and food.
The temperature and relative humidity were set to achieve limits of 17 to 23°C and 30 to 70%
respectively. The rate of air exchange was at least fifteen changes per
hour and the lighting was controlled by a time switch to give twelve hours continuous light (06:00
to 18:00) and twelve hours darkness.

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal and epicutaneous
Vehicle:
arachis oil
Concentration / amount:
For intradermal induction: 5% w/w in arachis oil BP.
For topical induction: 75%, 50%, 25% and 10% w/w in arachis oil BP.
For topical Challenge: 75%, 50%, 25% and 10% w/w in arachis oil BP
Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
arachis oil
Concentration / amount:
For intradermal induction: 5% w/w in arachis oil BP.
For topical induction: 75%, 50%, 25% and 10% w/w in arachis oil BP.
For topical Challenge: 75%, 50%, 25% and 10% w/w in arachis oil BP
No. of animals per dose:
Intradermal Induction: One guinea pig.
Topical induction: Two guinea pigs.
Topical Challenge: Two guinea pigs.
Main study: A group of fifteen guinea pigs was used for the main study, ten test and five control.
Details on study design:
Selection of concentrations for main study:
Selection of concentration for Intradermal study: Intradermal injections (0.1ml/injection site) were made on the clipped shoulder of one guinea pig, at a concentration of 5% w/w in arachis oil BP. The degree of erythema at the injection sites was assessed approx. 24, 48, 72 and 7 days after injection.
Selection of concentration for tropical induction: Two guinea pigs (intradermally injected with Freund's Adjuvant seven days earlier) were treated with four preparations of the test material (75%, 50%, 25% and 10% w/w in arachis oil BP). Applications were made to the clipped flanks under occlusive dressings for an exposure period of 48 hr. The degree of erythema and oedema was evaluated approx. 1, 24 and 48 hr after dressing removal. The highest concentration producing only mild to moderate dermal irritation was selected for the topical induction stage of the main study.
Selection of concentration for topical challenge: Four preparations of the test material (75%, 50%, 25% and 10% w/w in arachis oil BP) were applied to the clipped flanks of two guinea pigs under occlusive dressings for an exposure period of 24 hr. These guinea pigs did not form part of the main study but had been treated identically to the control animals of the main study, up to day 14. The degree of erythema and oedema was evaluated approx. 1, 24 and 48 hr after dressing removal.The highest non-irritant concentration of the test material and one lower concentration were selected for the topical challenge stage of the main study.
Main study:
group of fifteen guinea pigs was used for the main study, ten test and five control.
Two phases were involved in the main study (a) an induction of the response and (b) a challenge of that response
Induction:
Induction of test animals:
Test animals were injected with Freunds complete adjuvant plus distilled water in the ratioo 1:1; a 5% w/w formulation of the test material in arachis oil BP; a 5% w/w formulation of the test material in a 1:1 preparation of Freunds complete adjuvant pus distilled water.
Approx. 24 and 48 hr after injection the degree of erythema at the test injection sites were evaluated.
On day 7 the same area used for intradermal injections was clipped and treated with topical application of the test material formulation. The occlusive dressing was kept in place for 48 hr. The degree of erythema and oedema was quantified one and 24 hr following removal of the patches .
induction of control animals: The intradermal induction was performed using identical procedure to that used for the test animals except that the test material was omitted from the intradermal injections. Similarly, the topical induction procedure was identical to that used for the test animals except that the test material was omitted.
Challenge:
Shortly before treatment on day 21 a square filter paper patch loaded with the test material formulation at the maximum non-irritant concentration (75% w/w in arachis oil BP) was applied to the shorn right flank of each animal and was held in place with a strip of surgical adhesive tape. To ensure that maximum non-irritant concentration was used at challenge, the test material at a concentration of 50% w/w in arachis oil BP was similarly applied to a skin site on the left shorn flank. After 24 hr, the dressing was removed and discarded. Appox. 24 and 48 hr after challenge removal, the degree of erythema and oedema was quantified.
Challenge controls:
non
Positive control substance(s):
yes
Remarks:
2-MERCAPTOBENZOTHIAZOLE

Results and discussion

Positive control results:
2-MERCAPTOBENZOTHIAZOLE produced a 80% (8/10) sensitisation rate (see attacment)

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
48
Group:
test group
Dose level:
75% w/w
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
Moderate and confluent erythema was noted at the intradermal induction sites
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
48
Group:
test group
Dose level:
50% and 75%
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
Discrete or patchy to moderate and confluent erythema was noted at the intradermal induction sites of control group animals
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
48
Group:
negative control
Dose level:
0
No. with + reactions:
0
Total no. in group:
5
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
48
Group:
positive control
Dose level:
50 and 25%
No. with + reactions:
8
Total no. in group:
10
Remarks on result:
positive indication of skin sensitisation
Remarks:
strong sensitizer to guinea pigs skin

Any other information on results incl. tables

Skin Reactions Observed After Intradermal Induction:

Moderate and confluent erythema was noted at the intradermal induction sites of test group

animals.

Discrete or patchy to moderate and confluent erythema was noted at the intradermal induction

sites of control group animals.

Skin Reactions Observed After Topical Induction:

Discrete or patchy to moderate and confluent erythema with or without very slight to slight

oedema was noted at the topical induction sites of test group animals.

Discrete or patchy to moderate and confluent erythema was noted at the topical induction sites of

control group animals.

Bleeding from the intradermal injection sites was noted in eight test group animals and one

control group animal.

Skin Reactions Observed After Topical Challenge:

75% w/w in Arachis Oil BP:

No skin reactions were noted at the challenge sites of the test or control group animals at the 24 or

48-hour observations.

50% w/w in Arachis Oil BP:

No skin reactions were noted at the challenge sites of the test or control group animals at the 24 or

48-hour observations.

Applicant's summary and conclusion

Conclusions:
Under the conditions of the test, the test material produced a 0% (0/10) sensitisation
rate and was classified as a non-sensitiser to guinea pig skin.