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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
refer to analogue justification provided in IUCLID section 13
Cross-reference
Reason / purpose:
read-across source
Reference
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Well documented study report, but no data on analytical purity of the substance, non-GLP, another positive control substance (DNCB) than recommended by TG OECD 406; 10 animals/group instead of recommended 20/group
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
17 July 1992
Deviations:
yes
Remarks:
/ another positive control substance (DNCB) than recommended by the guideline; 10 animals/group instead of 20/group as recommended
Principles of method if other than guideline:
The test procedure was based on the method described by Ritz & Buehler (1980).

Ritz H.L. & Buehler E.V. (1980). Current Concepts in Cutaneous Toxicity. Drill V.A. & Lazar T (Ed.), Academic Press, p. 25
GLP compliance:
no
Type of study:
Buehler test
Justification for non-LLNA method:
Test was done before LLNA as first-choice method for in-vivo testing was set into force.
Species:
guinea pig
Strain:
Hartley
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Strain: outbred Hartley white
- Source: Charles River Kingston, Route 209, Kingston, NY 12484, USA
- Age at study initiation: approx. 4 weeks old
- Weight at study initiation: 360 - 470 g
- Housing: individually in suspended stainless steel cages
- Diet: standard pellet diet (Purina Laboratory Guinea Pig Chow #5025), ad libitum
- Water: tap water, via automatic watering devices, ad libitum
- Acclimation period: at least 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.1 ± 5
- Humidity (%): 40 - 60
- Photoperiod (hrs dark / hrs light): 12 h dark / 12 h light

Route:
epicutaneous, occlusive
Vehicle:
other: (Squibb) Mineral Oil
Concentration / amount:
- Induction: 0.4 mL of a 50.0% (w/w) test substance solution in Squibb Mineral Oil
Day(s)/duration:
6 h
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
other: (Squibb) Mineral Oil
Concentration / amount:
- Challenge: 0.4 mL of a 25.0% (w/w) test substance solution in Squibb Mineral Oil
Day(s)/duration:
6 h
No.:
#2
Route:
epicutaneous, occlusive
Vehicle:
other: (Squibb) Mineral Oil
Concentration / amount:
Rechallenge: 0.4 mL of a 20.0% (w/w) or 12.5% test substance solution in Squibb Mineral Oil
Day(s)/duration:
6 h, 6 days after first exposure
No. of animals per dose:
- 4 animals for range-finding of primary irritation of the test substance (Irritation group)
- 10 test animals (Induction group)
- 10 control animals (Control group)
Details on study design:
RANGE FINDING TESTS:
- Primary irritation:
To determine the highest non-irritating concentration of the test material to be used in both the challenge and rechallenge phases of the test, a group of guinea pigs was treated with various concentrations of the test article.
Hair was removed from the entire back of 3 uncommitted guinea pigs using electric clippers. On the following day, patches were applied using a Hill Top Chamber System with a 25 mm Webril swatch moistened with 0.4 mL of either 100.0 (neat) or 75.0, 50.0, and 25.0% (w/w) test substance in Squibb Mineral Oil.
An irritant response was elicited by the 100.0, 75.0, 50.0, and 25.0% concentrations. Since even the lowest concentration of 25.0% (w/w) in mineral oil caused an irritant response, an additional group of 4 animals was used for a second primary irritation test. These animals were treated according to the procedure mentioned above. The concentrations of the test substance used were 50.0, 25.0, 10.0, and 5.0% (w/w) in Squibb Mineral oil.

The positive control material (DNCB) was administered in the same manner as for the test substance irritation groups. DNCB was administered at a concentration of 0.5, 0.1, or 0.05% (w/v) in acetone. These positive control irritation animals were also administered acetone via the chamber system.

The guinea pigs were wrapped with a piece of rubber dental dam (approx. 3"x4") that was placed over the patch site and secured with Elastoplast in order to ensure occlusive conditions. After an exposure period of approx. 6 h, the patches were removed and the treated sites wiped with cotton gauze wet with saline.
On the day following application of the test material, the clipped areas were depilated with Neet Cream Hair Remover. The depilatory was allowed to remain on the sites for 5 - 10 min and then wiped with cotton towels moistened with warm tap water. The patch sites were scored for erythema approx. 2 hours later (24-h reading) and approx. 24 h later (48-h reading) using the Draize scoring system.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3 exposures
- Exposure period: 6 h
- Control group: not treated
- Positive control group: DNCB was administered at a concentration of 0.1% (w/v) in 70% ethanol.
- Site: entire back
- Frequency of applications: once weekly
- Concentrations: 0.4 mL of 50.0% (w/w) in Squibb Mineral Oil
- Application: The patches were applied using a Hill Top Chamber with a 25 mm Webril swatch moistened with the substance. Then, the animals were wrapped with a piece of rubber dental dam (approx. 3"x4") that was placed over the patch site and secured with Elastoplast in order to ensure occlusive conditions.

- Rest period: 19 days

B. CHALLENGE EXPOSURE
- No. of exposures: 2 exposures (challenge and rechallenge after a 6-day rest period)
- Exposure period: 6 h
- Test group: treated as described
- Control group: treated as test group
- Positive control group: DNCB at 0.05% (w/v) in acetone
- Site: the lower right quadrant of the back for challenge; lower left and upper right quadrants of the back for rechallenge
- Concentrations: 0.4 mL of 25.0% (w/w) in Squibb Mineral Oil for challenge; 0.4 mL of 20.0% or 12.5% (w/w) in Squibb Mineral Oil for rechallenge
- Evaluation (hr after challenge): 24 h (after depilation for 5 - 10 min) and 48 h (without additional depilation)
- Application: The patches were applied using a Hill Top Chamber with a 25 mm Webril swatch moistened with the substance. Then, the animals were wrapped with a piece of rubber dental dam (approx. 3"x4") that was placed over the patch site and secured with Elastoplast in order to ensure occlusive conditions.

Challenge controls:
The control animals were maintained without treatment until primary challenge.
Positive control substance(s):
yes
Remarks:
2,4-Dinitrochlorobenzene (DNCB)
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
induction: 0%; challenge: 25%
No. with + reactions:
4
Total no. in group:
10
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
induction: 50%; challenge: 25%
No. with + reactions:
9
Total no. in group:
10
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
induction: 0.1%; challenge: 0.05%
No. with + reactions:
10
Total no. in group:
10
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
induction: 0%; challenge: 25%
No. with + reactions:
2
Total no. in group:
10
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
induction: 50%; challenge: 25%
No. with + reactions:
9
Total no. in group:
10
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
induction: 0.1%; challenge: 0.05%
No. with + reactions:
10
Total no. in group:
10
Reading:
rechallenge
Hours after challenge:
24
Group:
other: challenge control
Dose level:
induction: 0%; challenge: 12.5%
No. with + reactions:
0
Total no. in group:
5
Key result
Reading:
rechallenge
Hours after challenge:
24
Group:
test group
Dose level:
induction: 50%; challenge: 12.5%
No. with + reactions:
3
Total no. in group:
10
Reading:
rechallenge
Hours after challenge:
24
Group:
other: challenge control
Dose level:
Induction: 0%; challenge: 20%
No. with + reactions:
0
Total no. in group:
5
Key result
Reading:
rechallenge
Hours after challenge:
24
Group:
test group
Dose level:
induction: 50%; rechallenge: 20%
No. with + reactions:
4
Total no. in group:
10
Reading:
rechallenge
Hours after challenge:
48
Group:
other: challenge control
Dose level:
induction: 0%; challenge: 12.5%
No. with + reactions:
0
Total no. in group:
5
Reading:
rechallenge
Hours after challenge:
48
Group:
other: challenge control
Dose level:
induction: 0%; challenge: 20%
No. with + reactions:
0
Total no. in group:
5
Key result
Reading:
rechallenge
Hours after challenge:
48
Group:
test group
Dose level:
induction: 50%; rechallenge: 12.5%
No. with + reactions:
2
Total no. in group:
10
Key result
Reading:
rechallenge
Hours after challenge:
48
Group:
test group
Dose level:
induction: 50%; rechallenge: 20%
No. with + reactions:
4
Total no. in group:
10

Primary Irritation Tests:

 

1. Test:

In the evaluation of the primary irritation potential of the test substance, the 100.0% (neat) as well as the 75.0, 50.0, and 25.0% (w/w) concentrations produced significant irritant responses.

2. Test:

In the second test, significant dermal responses were observed at the highest concentration of 50.0%, but not at the lower concentrations. Based on these data, the 25.0% (w/w) concentration was determined to be the highest non-irritating concentration for challenge.

 

Challenge:

 

 

Number of animals showing indicated erythema score

 

Score

0

1

2

3

4

24-h reading

induced

1

4

5

0

0

 

control

6

2

2

0

0

 

positive control

0

0

4

5

1

48-h reading

induced

1

6

3

0

0

 

control

8

2

0

0

0

 

positive control

0

1

4

5

0

 

Rechallenge:

 

 

Number of animals showing indicated erythema score

 

Score

0

1

2

3

4

24-h reading

induced 12.5%     

7

3

0

0

0

 

induced 20.0%

6

3

0

1

0

 

control

10

0

0

0

0

48-h reading

induced 12.5%

8

1

1

0

0

 

induced 20.0%

6

1

3

0

0

 

control

10

0

0

0

0

Interpretation of results:
Category 1B (indication of skin sensitising potential) based on GHS criteria
Conclusions:
CLP: Skin Sens 1B, H317

Data source

Materials and methods

Test material

Reference
Name:
Unnamed
Type:
Constituent

Results and discussion

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
induction: 0%; challenge: 25%
No. with + reactions:
4
Total no. in group:
10
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
induction: 50%; challenge: 25%
No. with + reactions:
9
Total no. in group:
10
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
induction: 0.1%; challenge: 0.05%
No. with + reactions:
10
Total no. in group:
10
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
induction: 0%; challenge: 25%
No. with + reactions:
2
Total no. in group:
10
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
induction: 50%; challenge: 25%
No. with + reactions:
9
Total no. in group:
10
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
induction: 0.1%; challenge: 0.05%
No. with + reactions:
10
Total no. in group:
10
Reading:
rechallenge
Hours after challenge:
24
Group:
other: challenge control
Dose level:
induction: 0%; challenge: 12.5%
No. with + reactions:
0
Total no. in group:
5
Key result
Reading:
rechallenge
Hours after challenge:
24
Group:
test group
Dose level:
induction: 50%; challenge: 12.5%
No. with + reactions:
3
Total no. in group:
10
Reading:
rechallenge
Hours after challenge:
24
Group:
other: challenge control
Dose level:
Induction: 0%; challenge: 20%
No. with + reactions:
0
Total no. in group:
5
Key result
Reading:
rechallenge
Hours after challenge:
24
Group:
test group
Dose level:
induction: 50%; rechallenge: 20%
No. with + reactions:
4
Total no. in group:
10
Reading:
rechallenge
Hours after challenge:
48
Group:
other: challenge control
Dose level:
induction: 0%; challenge: 12.5%
No. with + reactions:
0
Total no. in group:
5
Reading:
rechallenge
Hours after challenge:
48
Group:
other: challenge control
Dose level:
induction: 0%; challenge: 20%
No. with + reactions:
0
Total no. in group:
5
Key result
Reading:
rechallenge
Hours after challenge:
48
Group:
test group
Dose level:
induction: 50%; rechallenge: 12.5%
No. with + reactions:
2
Total no. in group:
10
Key result
Reading:
rechallenge
Hours after challenge:
48
Group:
test group
Dose level:
induction: 50%; rechallenge: 20%
No. with + reactions:
4
Total no. in group:
10

Applicant's summary and conclusion

Interpretation of results:
Category 1B (indication of skin sensitising potential) based on GHS criteria
Conclusions:
CLP: Skin Sens 1B, H317
In a study according to OECD 406, the source substance was found to have skin sensitising potential. As explained in the analogue justification, this result is considered to be valid also for the target substance.