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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report Date:
1997

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
(1992)
GLP compliance:
yes (incl. certificate)
Type of study:
guinea pig maximisation test

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Strain: Hsd Poc:DH (SPF-bred)
- Source: Harlan Winkelmann GmbH Laboratory Animal Breeders, Borchen, Germany.
- Age at study initiation: 5 - 7 weeks
- Weight at study initiation: mean weight 319 - 342 g
- Housing: in groups of 2 or 3 in type IV Makrolon cages
- Diet and water: ad libitum
- Acclimation period: at least 7 days.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 3
- Humidity (%): 40-60
- Air changes (per hr): >/= 10
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal and epicutaneous
Vehicle:
paraffin oil
Concentration / amount:
intradermal induction: 5 % test substance
epicutaneous induction: 50 % test substance
challenge: 10 % test substance
Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
paraffin oil
Concentration / amount:
intradermal induction: 5 % test substance
epicutaneous induction: 50 % test substance
challenge: 10 % test substance
No. of animals per dose:
20 test animals/10 controls
Details on study design:
RANGE FINDING TESTS:
Intradermal induction: One guinea pig was given intradermal injections twice, in each case 0.1 mL of the test substance concentrations 0%, 1%, 2.5%, 5%. The injection sites were evaluated after 24 and 48 hours.
Epicutaneous induction: 4 guinea pigs were treated epidermally in each case with 0.5 mL of the test substance concentrations 0%, 25%, 50%, 100% under occlusive conditions for 24 hours. Skin reactions were evaluated 24 and 48 hours after removal of the patch. Evidence of skin irritating properties of the 100% test substance formulation was seen.
Challenge: 5 guinea pigs, that were treated in the same manner as the control animals during the inductions, received epidermally in each case 0.5 mL of the test substance concentrations 0%, 5%, 25%, 40% under occlusive conditions for 24 hours. Skin reactions were evaluated 24 and 48 hours after removal of the patch. Evidence of skin irritating properties of the 25% test substance formulation for challenge was seen.

MAIN STUDY:
Intradermal induction: The dorsal region and the flanks of the guinea pigs were shorn one day prior to the application. Starting behind the nape of the neck, 3 injections each in a row were made on the left and the right side of the spinal column. The 1st and 2 nd injections were made as contiguous as possible and the 2nd and 3rd injections in a distance of about 2 cm. The application volume is 0.1 mL/injection site, the test substance concentration is 5% in paraffin oil (injection site medial/bilateral) and 5% in paraffin oil/FCA 1/1 (injection site caudal/bilateral), respectively. Animals of the control group were treated in the same manner with the corresponding amount of the vehicle.

Epicutaneous induction: Performed one week after the intradermal induction. On the day prior to topical treatment, the test areas were shorn. Hypoallergenic patches (2 x 4 cm), treated with 0.5 mL 50 % test substance formulation (test group) or solely vehicle (control group) were placed between and on the injection sites, covered with aluminium foil and held securely in place on the skin using a self-adhesive tape. At the end of the 48-hour exposure period, remaining substance was removed with sterile physiological saline solution.

Challenge: Performed three weeks after the intradermal induction. The dorsal region and the right flank were shorn one day prior to the challenge. During the challenge hypoallergenic patches loaded with a 10 % test substance formulation was placed on the right flank (caudal, for test substance and control group) and held securely in place with a self-adhesive tape for 24 hours. A patch loaded only with the vehicle (0.5 mL application volume) was placed on the right flank (cranial) as control. At the end of the exposure period, remaining test substance was removed with paraffin oil, and 6 hours later the skin of the animals was shorn in the zone of the challenge area. The skin reactions were assessed 48 and 72 hours after start of the application.

EVALUATION CRITERIA: A substance is interpreted to be sensitizing if by comparison with the control group 30% or more of the test group animals reacted positive.
Positive control substance(s):
yes
Remarks:
, 2-Mercaptobenzothiazole

Results and discussion

Positive control results:
Using a 2,5 % formulation of 2-mercaptobenzothiazole for intradermal induction, a 40 % formulation for topical induction and a 40 % formulation for challenge, 60 % of the test animals exhibited dermal reactions. No reddening of the skin was observed on control group animals.

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
48
Group:
test group
Dose level:
10 %
No. with + reactions:
13
Total no. in group:
20
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 10 %. No with. + reactions: 13.0. Total no. in groups: 20.0.
Reading:
2nd reading
Hours after challenge:
72
Group:
test group
Dose level:
10 %
No. with + reactions:
17
Total no. in group:
20
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: test group. Dose level: 10 %. No with. + reactions: 17.0. Total no. in groups: 20.0.
Reading:
1st reading
Hours after challenge:
48
Group:
negative control
Dose level:
10 %
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 10 %. No with. + reactions: 0.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
72
Group:
negative control
Dose level:
10 %
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: negative control. Dose level: 10 %. No with. + reactions: 0.0. Total no. in groups: 10.0.

Any other information on results incl. tables

Appearance and behaviour of the test substance group were not different from the control group. By the end of the study the body weight development of the treatment group animals was in the same range as that of the control group.

None of the animals in the test group reacted to the control patch moistened with the vehicle. None of the animals in the control group reacted to the test substance formulation or to the vehicle.

48 hours after the beginning of the challenge treatment the test substance formulation led to skin redness (grade 1 or 2) in 13/20 animals in the test group, one of the 13 positive reacting animals showed additionally an oedema grade. 72 hours after the challenge 17/20 animals in the test group showed an erythema grade 1 or 2 and the oedema in the specified animal still persisted. In total, 19/20 animals in the test group (95%) showed skin reaction to the test substance formulation.

Applicant's summary and conclusion

Executive summary:

A Skin Sensitisation test (GPMT) was conducted according to OECD TG 406 on female guinea pigs (20 test animals and 10 controls). Based on range finding tests the following concentrations were used in the main test: 5 % for intradermal induction, 50 % for topical induction and 10 % for challenge. As vehicle paraffin oil was used.

48 and 72 hours after the beginning of the challenge treatment 19/20 (95 %) animals in the test group showed skin reaction to the 10% test substance formulation (erythema grade 1 or 2, oedema grade 1 in one animal). None of the animals in the control group showed skin reactions. Thus, under the conditions of the maximization test and with respect to the evaluation criteria the test substance exhibits a skin-sensitisation potential.