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Description of key information

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:
1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: According to guideline; under GLP conditions
Qualifier:
according to guideline
Guideline:
EPA OPP 81-6 (Skin Sensitisation)
Deviations:
no
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
Qualifier:
equivalent or similar to guideline
Guideline:
EU Method B.6 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Species:
guinea pig
Strain:
other: Crl :(HA)BR
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Recognised animal supplier
- Age at study initiation: not reported
- Weight at study initiation: 351 - 421 g
- Housing: individually housed in screen-bottom stainless steel cages.
- Diet (e.g. ad libitum): certified guinea pig diet ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 25
- Humidity (%): 50 +/- 20
- Air changes (per hr): not reported
- Photoperiod (hrs dark / hrs light): 12h light / 12h dark

IN-LIFE DATES: From: To: 1995-07-11 to 1995-08-21
Route:
intradermal and epicutaneous
Vehicle:
other: mineral oil and petrolatum
Concentration / amount:
Preliminary skin irritation study: 1, 10, 15 and 25 %w/w
Induction dose: 25% w/w
Challenge dose: 25% w/w
Route:
epicutaneous, occlusive
Vehicle:
other: mineral oil and petrolatum
Concentration / amount:
Preliminary skin irritation study: 1, 10, 15 and 25 %w/w
Induction dose: 25% w/w
Challenge dose: 25% w/w
No. of animals per dose:
Group 1 - Preliminary skin irritation study: 4
Group 2 - Main test: 20
Group 3 - Irritation control: 10
Group 4 - Positive control (sulfathiazole): 10
Group 5 - Positive control-irritation control: 5
Details on study design:
RANGE FINDING TESTS:
The purpose of the irritation screening study was to find a moderately irritating dose level to use for the topical application and the highest non-irritating concentration to be used for the challenge application. Four animals were treated with the test material at concentrations of 1%, 10%, 15%, and 25% w/w in petrolatum. Each animal received two different concentrations of the test material. The test material concentrations were applied in a thick even layer to 2-cm x 2-cm Whatman No. 3 filter papers, applied to two sites (one on the right side and one on the left side) on the shaved back of each animal, covered with overlapping strips of Blenderm tape, and overwrapped with Elastoplast® tape. The patches remained in place for 24 hours after which they were removed. The application sites were observed for dermal reactions at approximately 24 and 48 hours after patch removal.

MAIN STUDY
A. INDUCTION EXPOSURE
Animals in Groups 2 and 4 received duplicate 0.1-ml intradermal injections on the shoulder area of a 1:1 dilution of Freund's Complete Adjuvant in sterile water, a 5% w/v suspension of the test material in mineral oil (Group 2) or a 5% w/v suspension of sulfathiazole in sterile water (Group 4), and a 5% w/v suspension of the test material in Freund's Complete Adjuvant in sterile water (Group 2) or a 5% w/v mixture of sulfathiazole in sterile water in Freund's Complete Adjuvant (Group 4). Animals in Groups 3 and 5 received duplicate 0.1-ml intradermal injections of a 1:1 dilution of Freund's Complete Adjuvant in sterile water, the respective vehicle (mineral oil for Group 3 or sterile water for Group 5) alone, and a 1:1 dilution of the respective vehicle in Freund's Complete Adjuvant in the same manner as for the animals in Groups 2 and 4. Six days later, the animals in Groups 2 through 5 were pretreated with sodium lauryl sulfate applied topically at the injection sites. On Day 8, a 25% w/w mixture of test material in petrolatum was applied over the injection sites of the animals in Group 2, a 25% w/w mixture of sulfathiazole in petrolatum was applied over the injection sites of the animals in Group 4, and petrolatum was applied over the injection sites of the animals in Groups 3 and 5. All induction sites were then occluded for 48 hours.

B. CHALLENGE EXPOSURE
Two weeks after the topical application, all animals received a challenge dose. A 25% w/w mixture of test material in petrolatum was applied to the
right side and the control material (petrolatum) was applied to the left side of each animal in Groups 2 and 3. A 10% w/w mixture of sulfathiazole in
petrolatum was applied to the right side and petrolatum alone was applied to the left side of each animal in Groups 4 and 5. All test and control sites
were occluded for 24 hours and then wiped clean. The challenge sites were examined for dermal reactions at 24 and 48 hours after patch removal.
Challenge controls:
Petrolatum alone
Positive control substance(s):
yes
Remarks:
sulfathiazole
Positive control results:
All animals in Group 4 {positive control) exhibited slight to moderate sensitization reactions on the test sites treated with sulfathiazole
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
25% w/w
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: 25% w/w. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
25% w/w
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: 25% w/w. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
Petrolatum (control)
No. with + reactions:
0
Total no. in group:
35
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: Petrolatum (control). No with. + reactions: 0.0. Total no. in groups: 35.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
Petrolatum (control)
No. with + reactions:
0
Total no. in group:
35
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: Petrolatum (control). No with. + reactions: 0.0. Total no. in groups: 35.0.
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
10% sulfathiazole
No. with + reactions:
10
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: positive control. Dose level: 10% sulfathiazole. No with. + reactions: 10.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
10% sulfathiazole
No. with + reactions:
10
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: positive control. Dose level: 10% sulfathiazole. No with. + reactions: 10.0. Total no. in groups: 10.0.
Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: US EPA pesticides
Conclusions:
Under the conditions of this study, the test material is not considered to be a skin sensitiser.
Executive summary:

The study was performed to assess the skin sensitisation potential of the test material in Crl :(HA)BR male guinea pigs following the guinea pig maximisation method. The study was performed to GLP and the method was designed to meet the requirements of EPA OPP 81-6 and equivalent methodology to OECD Guideline 406 and EU Method B.6. In a preliminary skin irritation screening test in 4 test animals were treated with the test material at concentrations of 1%, 10%, 15%, and 25% w/w in petrolatum and were applied to the shaved backs for a period of 24 hours. The test material caused no dermal reaction in any animal at any concentration and was therefore administered as a 25% w/w mixture in petrolatum for the topical induction application and for the challenge phase in the definitive study. In the main study, a group of 45 test animals (20 test animals treated with test material, 10 animals serving as an irritation control, 10 animals serving as a positive control and 5 animals serving as a positive control-irritation control) received induction doses by intradermal injection and topical application. The intradermal injections were made within the boundaries of a 2 -cm x 4 -cm area, one row of three injections on each side of the midline. Each animal received the following: anterior sites: 0.1 ml of a 1:1 dilution of Freund's Complete Adjuvant in sterile water; medial site: 0.1ml test material in Freund's Complete Adjuvant in sterile water / positive control in sterile water in Freund's Complete Adjuvant / vehicle in Freund's Complete Adjuvant. On Day 7 test animals backs were shaved and pretreated with a 10% w;w sodium lauryl sulfate (SLS) suspension in petrolatum before the topical induction application. A 25% w/w mixture of test material in petrolatum, a 25% w;w mixture of sulfathiazole (positive control substance) in petrolatum, or petrolatum was applied over the injection sites of the animals in the respective groups. The patches were covered with overlapping strips of BlendermN tape and secured by an overwrap of Elastoplast® tape wound around the trunk and remained in place for 48 hours. 2 weeks after the topical induction, a topical challenge dose was applied. A 25% w/w mixture of test material in petrolatum and petrolatum alone or a 10% w/w mixture of sulfathiazole in petrolatum and petrolatum alone were applied to the backs of the test animals. The filter paper containing the test or positive control material mixture was placed on the right side and the filter paper containing petrolatum alone was placed on the left side of each animal. The patches were sealed for 24 hours under occlussive dressing. Twenty-four hours after application, the wrappings were removed and the test sites wiped clean with wet disposable paper towels. The test sites were closely shaved approximately 3 hours before the 24-hour challenge observation.

None of the test animals exhibited a dermal reaction to the challenge application of the test or control materials. All animals of the positive control group exhibited slight to moderate sensitization reactions on the test sites treated with sulfathiazole and no dermal reactions on the test sites treated with petrolatum alone. None of the animals in the positive control-irritation control exhibited a dermal reaction to the challenge application of sulfathiazole or petrolatum. Based on these results, the test material is not considered to be a skin sensitizer in guinea pigs.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

EPA OPP 81-6, Glaza 1995f:

The study was performed to assess the skin sensitisation potential of the test material in Crl :(HA)BR male guinea pigs following the guinea pig maximisation method. The study was performed to GLP and the method was designed to meet the requirements of EPA OPP 81-6 and equivalent methodology to OECD Guideline 406 and EU Method B.6. In a preliminary skin irritation screening test in 4 test animals were treated with the test material at concentrations of 1%, 10%, 15%, and 25% w/w in petrolatum and were applied to the shaved backs for a period of 24 hours. The test material caused no dermal reaction in any animal at any concentration and was therefore administered as a 25% w/w mixture in petrolatum for the topical induction application and for the challenge phase in the definitive study. In the main study, a group of 45 test animals (20 test animals treated with test material, 10 animals serving as an irritation control, 10 animals serving as a positive control and 5 animals serving as a positive control-irritation control) received induction doses by intradermal injection and topical application. The intradermal injections were made within the boundaries of a 2 -cm x 4 -cm area, one row of three injections on each side of the midline. Each animal received the following: anterior sites: 0.1 ml of a 1:1 dilution of Freund's Complete Adjuvant in sterile water; medial site: 0.1ml test material in Freund's Complete Adjuvant in sterile water / positive control in sterile water in Freund's Complete Adjuvant / vehicle in Freund's Complete Adjuvant. On Day 7 test animals backs were shaved and pretreated with a 10% w;w sodium lauryl sulfate (SLS) suspension in petrolatum before the topical induction application. A 25% w/w mixture of test material in petrolatum, a 25% w;w mixture of sulfathiazole (positive control substance) in petrolatum, or petrolatum was applied over the injection sites of the animals in the respective groups. The patches were covered with overlapping strips of BlendermN tape and secured by an overwrap of Elastoplast® tape wound around the trunk and remained in place for 48 hours. 2 weeks after the topical induction, a topical challenge dose was applied. A 25% w/w mixture of test material in petrolatum and petrolatum alone or a 10% w/w mixture of sulfathiazole in petrolatum and petrolatum alone were applied to the backs of the test animals. The filter paper containing the test or positive control material mixture was placed on the right side and the filter paper containing petrolatum alone was placed on the left side of each animal. The patches were sealed for 24 hours under occlusive dressing. Twenty-four hours after application, the wrappings were removed and the test sites wiped clean with wet disposable paper towels. The test sites were closely shaved approximately 3 hours before the 24-hour challenge observation.

None of the test animals exhibited a dermal reaction to the challenge application of the test or control materials. All animals of the positive control group exhibited slight to moderate sensitisation reactions on the test sites treated with sulfathiazole and no dermal reactions on the test sites treated with petrolatum alone. None of the animals in the positive control-irritation control exhibited a dermal reaction to the challenge application of sulfathiazole or petrolatum. Based on these results, the test material is not considered to be a skin sensitiser in guinea pigs.

 

Buehler method, EPA OPP 81-6, Glaza 1995g:

The study was performed to assess the skin sensitisation potential of the test material in Crl :(HA)BR male guinea pigs following the Buehler method. The study was performed to GLP and the method was designed to meet the requirements of EPA OPP 81 -6 and OECD Guideline 406. In a preliminary skin irritation screening test in 4 test animals were treated with the test material at concentrations of 25%, 50%, 75%, and 100% w/w in methylcellulose and were applied to the shaved backs for a period of 6 hours. The test material caused no dermal reaction in any animal at any concentration and was therefore administered as a 100% w/w mixture in methylcellulose for the topical induction application and for the challenge phase in the definitive study. In the main study, a group of 10 test animals received induction doses by topical application. The appropriate test material concentrations, in the amount of 0.4 g or 0.4 ml, were applied to adhesive patches {Hill Top Chamber®, 25-mm diameter). The patches were then placed on two shaved sites (one on the right and one on the left anterior dorsal quadrants) on each animal, covered with an overlapping strip of dental dam, and overwrapped with Elastoplast® tape. The patches remained in place for 6 hours after which they were removed and the sites washed with warm tap water and patted dry with a disposable paper towel. A negative control group of 10 animals were not treated with an induction dose. A positive control group of 4 animals received an induction dose with the positive control material, 0.3% w/v 2,4-dinitrochlorobenzene (DNCB) in 80% v/v ethanol in deionized water and was administered as a 0.4-ml dose to the positive control animals in the same manner used for the test material. Two weeks following the administration of the last induction dose, a challenge dose of 0.4 g of test material (moistened with approximately 0.2 ml of 0.5% methylcellulose) was administered along the dorsal anterior right quadrant of the test group animals in the same manner as during the induction phase of the study. At this time the 10 negative control animals were also treated in the same manner with a challenge application of the test material. The positive control material was administered as a 0.4-ml dose at a concentration of 0.1% w/v in acetone. The respective application sites were examined and scored for dermal reactions according to the Buehler scoring scale at approximately 24 and 48 hours following the irritation screening, induction, and challenge applications.

None of the test animals exhibited a dermal reaction to the challenge application of the test materials. All animals of the positive control group exhibited moderate to severe sensitisation reactions. None of the animals in the negative control groups exhibited a dermal reaction to the challenge application of the test material. Based on these results, the test material is not considered to be a skin sensitiser in guinea pigs.


Migrated from Short description of key information:
Not sensitising, EPA OPP 81-6, Glaza 1995f
Not sensitising (Buehler method), EPA OPP 81-6, Glaza 1995g

Justification for selection of skin sensitisation endpoint:
Two studies available, both GLP compliant and Klimisch 1; both studies indicate no positive reaction to dermal exposure. Selected study representative of the lowest dose descriptor.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

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