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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:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study with acceptable restrictions (use of an irritating dose for challenge exposure; lack of data on test substance)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995
Report Date:
1995

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
yes
Remarks:
(use of an irritating dose for challenge exposure; lack of data on test substance)
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
A non-LLNA test is available that was performed prior to the current data requirements, stipulated in Regulation (EC) No 1907/2006. In accordance with the same Regulation, the data were included to avoid unnecessary testing.

Test material

Reference
Name:
Unnamed
Type:
Constituent

In vivo test system

Test animals

Species:
guinea pig
Strain:
other: Hartley Albino
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Raleigh, NC, USA
- Age at study initiation: ca. 5 weeks
- Weight at study initiation: 286 - 342 g
- Housing: animals were housed separately in suspended stainless steel and wire mesh cages with absorbent paper below the cages.
- Diet: Agway PROLAB Certified Guinea Pig Chow, ad libitum
- Water: tap water, ad libitum
- Acclimation period: 9 d

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 - 22
- Humidity (%): 40 - 70
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES:
From: 14 Sep 1995
To: 16 Oct 1995

Study design: in vivo (non-LLNA)

Induction
Route:
intradermal and epicutaneous
Vehicle:
other: peanut oil, FCA
Concentration / amount:
intradermal: 5%
epicutaneous: 100%
Challenge
Route:
epicutaneous, occlusive
Vehicle:
other: peanut oil, FCA
Concentration / amount:
50%
No. of animals per dose:
10 irritation control animals, 10 positive control animals, 20 animals in test groups
Details on study design:
RANGE FINDING TESTS:
A primary irritation test (PIT) was performed to determine suitable concentrations for intradermal and epicutaneous induction. Therefore, three concentrations of the test substance (0.1, 1.0 and 5.0% v/v in peanut oil) were administered intradermally to 2 animals per concentration. The injection sites were evaluated 24 and 48 h after injection. None of the injection sites for the 5.0% animals showed skin corrosion or irritation at either the 24 or 48 h observations. Therefore, 5% of the test substance was chosen for intradermal induction. The PIT also indicated that 100% of the test substance applied topically produced mild to moderate irritation whereas 50% of the test substance was non-irritating. Therefore, concentrations of 100% of the test substance were chosen for the topical induction dose and 50% for the challenge dose, respectively.

MAIN STUDY
A. INDUCTION EXPOSURE
On Day 0, 3 pairs of intradermal injections (0.1 mL) were made in the shoulder region of the test animals. On Day 7, 100% of the test substance (0.5 mL) was applied topically under occlusive conditions for 48 h on the shoulder region of the test animals.
- Exposure period: 3 single injections (intradermal) and 48 h (epicutaneous)
- Test groups:
Intradermal (3 pairs of injections):
Injection 1: a 1:1 mixture (v/v) FCA/water
Injection 2: 5% (v/v) test substance in peanut oil
Injection 3: 5% (v/v) test substance in a 1:1 mixture (v/v) FCA/water

Epicutaneous: test substance (0.5 mL, occlusive conditions)

Evaluation: 1 and 24 h after each induction

- Control group:
Injection 1: a 1:1 mixture (v/v) FCA/water
Injection 2: peanut oil
Injection 3: peanut oil in a 1:1 mixture (v/v) FCA/water

Epicutaneous: peanut oil (0.5 mL, occlusive conditions)

Evaluation: 1 and 24 h after each induction

B. CHALLENGE EXPOSURE
On Day 21, the test substance in peanut oil (50% (v/v, 0.4 mL) was applied topically under occlusive conditions for 24 h to all animals.
- No. of exposures: 1
- Exposure period: 24 h
- Test groups: test substance in peanut oil (left flank) and peanut oil only (right flank)
- Control group: test substance in peanut oil (left flank) and peanut oil only (right flank)
- Evaluation (hr after challenge): 24 and 48 h

Due to the fact that the challenge dosing with 50% test substance was more irritating than is ideal for the challenge and rechallenge phases, the concentration for rechallenge dosing was lowered to 10% of the test substance.

C. RECHALLENGE EXPOSURE
On Day 28, the test substance in peanut oil (10% (v/v, 0.4 mL) was applied topically under occlusive conditions for 24 h to all animals.
- No. of exposures: 1
- Exposure period: 24 h
- Test groups: test substance in peanut oil (right flank) and peanut oil only (left flank)
- Control group: test substance in peanut oil (right flank) and peanut oil only (left flank)
- Evaluation (hr after rechallenge): 24 and 48 h after patch removal
Challenge controls:
The control group is actually a challenge control.
Positive control substance(s):
yes
Remarks:
2-Mercaptobenzothiazole (MBT): intradermal induction: 3%, epicutaneous induction: 25%, challenge: 0.5%; no rechallenge was done

Results and discussion

Positive control results:
The positive control substance (0.4% 2-Mercaptobenzothiazole in peanut oil) induced positive reactions in 10/10 animals (100%), thus meeting the reliability criteria.

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
5%
No. with + reactions:
9
Total no. in group:
10
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
5%
No. with + reactions:
18
Total no. in group:
20
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
3%
No. with + reactions:
10
Total no. in group:
10
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
5%
No. with + reactions:
7
Total no. in group:
10
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
5%
No. with + reactions:
7
Total no. in group:
20
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
3%
No. with + reactions:
10
Total no. in group:
10
Reading:
rechallenge
Hours after challenge:
24
Group:
negative control
Dose level:
5%
No. with + reactions:
5
Total no. in group:
10
Reading:
rechallenge
Hours after challenge:
24
Group:
test group
Dose level:
5%
No. with + reactions:
4
Total no. in group:
20
Reading:
rechallenge
Hours after challenge:
48
Group:
negative control
Dose level:
5%
No. with + reactions:
0
Total no. in group:
10
Reading:
rechallenge
Hours after challenge:
48
Group:
test group
Dose level:
5%
No. with + reactions:
0
Total no. in group:
20

Any other information on results incl. tables

In the test group and the irritation control animals, the 3 intradermal injections of the intradermal induction produced slight to moderate redness around the injection sites at either 1 and 24 h after injection. The topical application of 100% of the test substance for 24 h under occlusive conditions leads to very slight to well-defined erythema in 18/20 animals and severe erythema to slight eschar formation in one animal at the 1 and 24 h observations. Moderate to severe erythema formation was observed in one animal after 24 h. At the 1 h reading, very slight to slight edema were noted in 12/20 animals. At the 24 h reading, very slight to moderate edema were observed in 19/20 animals.

The topical application of peanut oil produced results similar to the treated animals. In all 10 irritation control animals, very slight to severe erythema and very slight to slight edema were noted at the 1 and 24 h observation time points.

The topical challenge dose of 50% test substance in peanut oil leads to very slight erythema in 11/20 animals and to well-defined erythema in 7/20 animals at the 24 h evaluations in test group animals. At the 48 h reading, 6/20 animals had very slight erythema, one animal had well-defined erythema and 13/20 animals were free of erythema. Very slight edema were observed in 4/20 treated animals at the 24 h observation and in one animal at the 48 h observation. In the irritation control group, the topical application of 50% test substance in peanut oil produced very slight erythema in 4/10 animals and well-defined erythema in 5/10 animals at the 24 h reading. At the 48 h observation, 6/10 animals had very slight erythema and one animal had well-defined erythema. Edema was not observed in any irritation control animal at the 24 or 48 h reading.

Since the severity of the erythema was similar between the treated group and the irritation control group and the incidence of erythema was higher in the irritation control group, the response was considered an irritation response and not a sensitization response. An examination of the individual animals' responses showed that the majority of the irritation scores decreased from the 24 h evaluation to the 48 h evaluation, which also is indicative of an irritation and not a sensitization response. However, since there was some irritation from the challenge application, it was decided to rechallenge at a lower concentration to confirm that the test material possessed no sensitization potential.

The rechallenge was performed with 10% test substance in peanut oil and produced very slight erythema in 4/20 animals at the 24 h observation. All animals were free of erythema at the 48 h evaluation. Edema was not observed in any treated animals at the 24 or 48 h observations.

In the irritation control group, topical application of 10% test substance in peanut oil leads to very slight erythema in 4/10 animals and well-defined erythema in one animal at the 24 h observation. All animals were free of erythema at the 48 h evaluation. Edema were not observed in any irritation

control animal at the 24 or 48 h observations.

Applicant's summary and conclusion

Interpretation of results:
other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No. 1272/2008.