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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
other: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1994
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
study conducted on the analogue substance; The Reliability of the Source Study is 1.
Justification for type of information:
The read across justification is detailed in section 13.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1994
Report Date:
1994

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
Old studies NON LLNA available

Test material

Reference
Name:
Unnamed
Type:
Constituent

In vivo test system

Test animals

Species:
guinea pig
Strain:
other: HsdWin:DH
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source:
- Age at study initiation: 5-7 weeks
- Weight at study initiation: 316-406 g
- Housing: 2-3 per cage throughout the study
- Diet ad libitum
- Water ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21
- Humidity (%): 40-70
- Air changes (per hr): 12-15
- Photoperiod (hrs dark / hrs light): 12 / 12

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal
Vehicle:
physiological saline
Concentration / amount:
5 %
Day(s)/duration:
one injection
Route:
epicutaneous, semiocclusive
Vehicle:
physiological saline
Concentration / amount:
50 %
Day(s)/duration:
48 h
Challengeopen allclose all
No.:
#1
Route:
epicutaneous, semiocclusive
Vehicle:
physiological saline
Concentration / amount:
50 % and 25 %
Day(s)/duration:
after three weeks for 24 h
No.:
#2
Route:
epicutaneous, semiocclusive
Vehicle:
physiological saline
Concentration / amount:
50 % and 25 %
Day(s)/duration:
after four weeks for 24 h
No. of animals per dose:
20
Details on study design:
Test Substance Formulation
Prior to each treatment the test substance was formulated (w/v) in sterile physiological saline solution to yield a suspension.
The formulations were continuously homogenized on a magnetic stirrer during the treatments.
The stability and homogeneity of the test substance in the formulations were analytically.
Three groups of animals were allocated by random selection to the main study: one test substance group consisting of 20 experimental animals (nos. 21 - 40), and two control groups made up of 10 animals each (nos. 1 - 10 and 11 -20). The second control group was held in reserve in case a second challenge might be necessary to check any ambiguous results from the first challenge, or to investigate concentration relationships if the first challenge produced positive results. The randomization list was generated on an IBM computer system using the Randu subroutine from IBM Scientific Subroutine Package.
The animals were identified using cage cards specifying the test substance, study number, animal number, dose and sex, and by individual markings using aqueous picric acid solution.

Dose Selection
The doses for the induction and challenge treatments were selected on the basis of the results of the dose range-finding studies. The selection of doses for the second challenge exposure was based on the results of the 1st challenge.
Challenge controls:
The animal of the control groups were treated in the same manner as the animals of the test substance group; however, the formulations did not contain any test substance but a corresponding amount of sterile physiological saline.
Positive control substance(s):
yes
Remarks:
2-mercaptobenzothiazole formulated with physiological NaCl

Results and discussion

Positive control results:
After the 1st challenge with a 40% and 12% test substance formulation 80% and 55% of the test animals exhibited dermal alterations. After the 2nd challenge both with 3% and 1% test substance formulations 15 % of the test animals developed dermal signs. There was no reddening of the skin to be observed on control group animals.
In another test series with 2-mercaptobenzothiazole and the Same induction concentrations 80% and 65% of the test animals showed reactions to the 1st challenge using 40% and 25% test substance formulations, and 80% and 75% of the animals to the 2nd challenge using 12% and 6% concentrations, while the control group animals exhibited no skin redness.
The sensitivity as well as the reliability of the maximization test method is thus confirmed by both studies.

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
50 %
No. with + reactions:
4
Total no. in group:
20
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
25 %
No. with + reactions:
8
Total no. in group:
20
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
50 %
No. with + reactions:
3
Total no. in group:
20
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
25 %
No. with + reactions:
7
Total no. in group:
20
Reading:
rechallenge
Hours after challenge:
24
Group:
test group
Dose level:
50 %
No. with + reactions:
14
Total no. in group:
20
Reading:
rechallenge
Hours after challenge:
24
Group:
test group
Dose level:
25 %
No. with + reactions:
9
Total no. in group:
20
Reading:
rechallenge
Hours after challenge:
48
Group:
test group
Dose level:
50 %
No. with + reactions:
9
Total no. in group:
20
Reading:
rechallenge
Hours after challenge:
48
Group:
test group
Dose level:
25 %
No. with + reactions:
9
Total no. in group:
20
Reading:
other: 1st and 2nd readings after challenge and rechallenge
Hours after challenge:
48
Group:
negative control
Dose level:
0 %
No. with + reactions:
0
Total no. in group:
10

Any other information on results incl. tables

Since the test substance was found not to cause a primary skin irritation in the dose range-finding study, the treated areas of the animals were irritated with sodium lauryl sulfate prior to the topical induction.

After the 2nd induction some animals of the first control and test substance group showed encrustations in places on the treatment areas.

After the 1st challenge, 4 (20%) and 8 (40%) of the test substance animals responded with "very mild" (barely visible) redness to the 50% and 25% test substance formulation. Skin reddenings were not found in the control group animals.

After the 2nd challenge, 14 (70%) and 9 (45%) of the test substance animals responded with "very mild" (barely visible) to readily visiblew redness to the 50% and 25% test substance formulation. Skin reddenings were not found in the control group animals.

Applicant's summary and conclusion

Interpretation of results:
other: Classified according to the CLP Regulation (EC) no.1272/2008 Skin sens. Cat. 1B
Conclusions:
The substance has sensitising properties.
Executive summary:

The maximization test of Magnusson and Kligman was performed on male guinea pigs to determine whether test item exhibits skin sensitization properties.

This GLP study was performed according to OECD Guideline No. 406. The study was conducted with the following test concentrations:

intradermal induction: 5%

topical induction: 50 %

first challenge: 50 and 25 %

second challenge: 50 and 25 %

formulated in sterile physiological saline solution to yield a suspension.

After the first challenge the 50 % and 25% formulations led to skin redness in 20 % and 40 % of the test animals respectively. There were no skin reactions in the control group.

After the second challenge the 50 % and 25 % formulations led to skin redness in 70 % and 45 % of the test animals, respectively. There were no skin reactions in the control group.

Therefore, the test item exhibits a definitive skin-sensitization potential under the conditions of the maximization test.

 


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