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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:
1988
Report Date:
1988

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
(1981)
GLP compliance:
yes
Type of study:
guinea pig maximisation test

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Stability under test conditions: The stability of the test item in the vehicle was analytically verified prior to study.

In vivo test system

Test animals

Species:
guinea pig
Strain:
other: DHPW
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Strain: DHPW, SPF-bred
- Source: Winkelmann, Borchen, Germany
- Age at study initiation: 5-8 weeks
- Weight at study initiation: 344-411 g
- Housing: in groups of 5 in Makrolon Typ IV cages (according to Meister, Zschr. Versuchstierkunde 7, 144-153, 1965) on low dust wood granulate bedding
- Diet and water: ad libitum
- Acclimation period: at least 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2
- Humidity (%): approx. 50
- Air changes (per hr): approx. 10
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal and epicutaneous
Vehicle:
other: acetone/peanut oil 10:90
Concentration / amount:
intradermal induction: 1 % test substance
epicutaneous induction: 100 % test substance
challenge: 25 % test substance
re-challenge: 3 % test substance
Challengeopen allclose all
Route:
epicutaneous, semiocclusive
Vehicle:
other: acetone/peanut oil 10:90
Concentration / amount:
intradermal induction: 1 % test substance
epicutaneous induction: 100 % test substance
challenge: 25 % test substance
re-challenge: 3 % test substance
No. of animals per dose:
20
Details on study design:
RANGE FINDING TESTS:
A pre-test for range finding was performed. In this pre-test intradermal concentrations of 0, 1, 2.5, and 5 % and epicutaneous concentrations of 12, 25, 50, and 100 % were tested for an assessment of tolerability. The pre-experiment for challenge used epicutaneous doses of 12, 25, 50, and 100 %. Based on the results of the pre-experiments the concentrations for the main test were chosen.

MAIN STUDY

A. INDUCTION EXPOSURE:
Intradermal induction: The dorsal region and the flanks of the guinea pigs (20 animals + 2 x 10 for control groups) were shorn 24 hours prior to 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 distance between the injections were in the range 1-2 cm and the application volume was 0.1 mL/injection site. Injections were a) Freund's complete adjuvent/saline solution 1:1, b) test substance 1 % in acetone/peanut oil 10:90, c) test substance 1 % in acetone/peanut oil // Freund's complete adjuvant 1:1. Animals of the control group were treated in the same manner but without adding test substance.
Epicutaneous induction: One week following the intradermal induction the epicutaneous induction was performed. The application sites of the guinea pigs were shorn 24 hours prior to application and treated with 10 % sodium laurylsulfate. For induction hypoallergenic plaster treated with 100 % test substance or with vehicle (control) were applied to the skin and covered with aluminium foil and a self-adhesive tape. The exposure time was 48 hours.

B. CHALLENGE EXPOSURE:
3 and 5 weeks after the intradermal induction the challenge experiment was conducted. The dorsal region and the flanks of the guinea pigs were shorn 24 hours prior to application. On day of challenge a hypoallergenic plaster treated with 0.5 mL test substance at 25 % (challenge) or 3 % (re-challenge) was applied on the left flanks of the test and control group (one control group for challenge with 25 % and one for challenge with 3 %) and fixed with a semiocclusive dressing. For negative control the right flank of each animal was treated with 0.5 mL of the vehicle only. The exposure time was 24 hours, readings were 48 and 72 hours after test substance application.

Results and discussion

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
48
Group:
test group
Dose level:
25 %
No. with + reactions:
16
Total no. in group:
20
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 25 %. No with. + reactions: 16.0. Total no. in groups: 20.0.
Reading:
2nd reading
Hours after challenge:
72
Group:
test group
Dose level:
25 %
No. with + reactions:
5
Total no. in group:
20
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: test group. Dose level: 25 %. No with. + reactions: 5.0. Total no. in groups: 20.0.
Reading:
1st reading
Hours after challenge:
48
Group:
negative control
Dose level:
25 %
No. with + reactions:
1
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 25 %. No with. + reactions: 1.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
72
Group:
negative control
Dose level:
25 %
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: 25 %. No with. + reactions: 0.0. Total no. in groups: 10.0.
Reading:
other: rechallenge, 1st reading
Hours after challenge:
48
Group:
test group
Dose level:
3 %
No. with + reactions:
18
Total no. in group:
20
Remarks on result:
other: Reading:
Reading:
other: rechallenge, 2nd reading
Hours after challenge:
72
Group:
test group
Dose level:
3 %
No. with + reactions:
1
Total no. in group:
20
Remarks on result:
other: Reading:
Reading:
other: rechallenge, 1st and 2nd reading (48 and 72)
Group:
negative control
Dose level:
3 %
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading:

Any other information on results incl. tables

At challenge 16/20 test group animals reacted to the 25 % concentration and 18/20 to the re-challenge with a 3 % concentration. For challenge control (only treated with vehicle instead of test substance for intradermal and epicutaneous induction) 1/10 animals showed a positive skin reaction to the 25 % test substance, none reacted at re-challenge to the 3 % test substance. None of the test group animals showed a skin reaction on the right flank (solely vehicle treated at challenge).

The treatment was tolerated by the guinea pigs without clinical findings. No effect on body weight gain occurred compared to controls.

Applicant's summary and conclusion

Executive summary:

A guinea pig maximation test according to OECD TG 406 is available for the substance. In this study guinea pigs (20 for test and 10 for control groups) were induced intradermally with a 1 % test substance formulation (vehicle acetone/peanut oil) and, with a one week interval, epicutaneously with undiluted test substance. Animals of the control groups received the treatment without the addition of test substance (the amount of test substance was replaced by the vehicle). For challenge the test substance was applied epicutaneously at a 25 % concentration, and a further re-challenge used a 3 % concentration of the test substance.

48 hours after challenge 16/20 animals of the test group showed a positive skin reaction on the test substance-treated flanks. The re-challenge at 3 % confirmed the positive reaction (18/20). Only one positive skin reaction (1/10) occurred in the control group treated with a 25 % concentration, none occurred in the control group at 3 %.

Therefore the conclusion was drawn that the substance has a potential for skin sensitization.