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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:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1991
Report date:
1991

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Principles of method if other than guideline:
Modified Buehler test:
20 female animals were indiced by epidermal application of 0.4 ml (25% in water) of the test substance (3 times on 3 following weeks).
10 animals were included in the challenge control group and 10 in rechallenge control group.
The positive control dinitrochlorobenzene (DNBC) was applied to 5 animals with additional 3 animals as DNBC challenge control.
Blood samples were collected before and after the test period. After each induction, test sites were scored for dermal irritation. Following a rest period of 14 days, animals were exposed to challenge dose.
A rechallenge was performed on the test and challenge control animals 7 days after the challenge procedure. The extent and degree of skin reaction to the challenge exposure in the test animals is compared with that demonstrated by control animals which undergo sham treatment during induction and receive the challenge exposure.
GLP compliance:
yes
Remarks:
(Life Sciences Division, Springborn Laboratories Inc.)
Type of study:
Buehler test
Justification for non-LLNA method:
Study from 1991

Test material

Constituent 1
Chemical structure
Reference substance name:
ε-caprolactam
EC Number:
203-313-2
EC Name:
ε-caprolactam
Cas Number:
105-60-2
Molecular formula:
C6H11NO
IUPAC Name:
azepan-2-one
Specific details on test material used for the study:
- Name of test material (as cited in study report): Caprolactam
- Physical state: white flakes
- Lot/batch No.: S1:600142 F from BASF Corporation Chemicals Division, New Jersey

In vivo test system

Test animals

Species:
guinea pig
Strain:
Hartley
Sex:
female
Details on test animals and environmental conditions:
Except as noted below, all animal housing and care conformed to AAALAC standards and to those published in the Guide for the Care and Use of Laboratory Animals, NIH Publication No. 86-23.

TEST ANIMALS
- Source: Harlan Sprague Dawley Inc., Indiana
- Housing: single
- Diet (e.g. ad libitum): Agway Prolab Guinea Pig formula
- Water (e.g. ad libitum): rap water
- Acclimation period: 5 days


ENVIRONMENTAL CONDITIONS
- Photoperiod (hrs dark / hrs light):12/12

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
water
Concentration / amount:
0.4 ml of 25 % test substance in water for induction and challenge
Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
water
Concentration / amount:
0.4 ml of 25 % test substance in water for induction and challenge
No. of animals per dose:
Test group: 20
Challenge control group: 10
Rechallenge control group: 10
Positive control group: 5
DNCB Challenge control group: 3
Details on study design:
RANGE FINDING TESTS:
A repeated (3x) application preliminary irritation screen was performed to determine an appropriate concentration of the test article for induction and challenge. Four concentrations of Caprolactam were applied to the exposed skin of 4 each range-finding animals: 75%, 50%, 25% and 10% w/v Caprolactam in sterile water. Each concentration was first applied to a Webril patch (0.4 ml/patch) and the patches immediately applied to the animals. Approximately 6 hours after dosing, the dental dam and patches were removed and sites were graded for dermal irritation at 24 hours after the exposure according to the following scale:
0 - No reaction
± - Slight patchy erythema
1- Slight confluent or moderate patchy erythema
2 - Moderate erythema
3 - Severe erythema with, or without edema

Based on slight patchy erythema and desquamation, concentration of 25% was chosen for induction, challenge and rechallenge.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3
- Exposure period: 6 h
- Test group: a Webril patch containing 0.4 ml of 25% w/v Caprolactam in sterile water
- Control group: a Webril patch containing 0.4 ml of sterile water
- Site: left shoulder
- Frequency of applications: 3 (1 per week)
- Duration: 3 weeks
- Following each induction, test sites were scored for dermal irritation using the scale presented previously (24 and 48 hours postdose).

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- 14 day rest period
- Exposure period: 6 h
- Test group: a Webril patch containing 0.4 ml of 25% w/v Caprolactam in sterile water
- Control group: a Webril patch containing 0.4 ml of sterile water
- Site: posterior left flank
- Evaluation (hr after challenge): 24 and 48 according to the Dermal Irritation Grading System as described above


C. RECHALLENGE EXPOSURE
- No. of exposures: 1
- 7 day rest period after first challenge
- Exposure period: 6 h
- Test group: a Webril patch containing 0.4 ml of 25% w/v Caprolactam in sterile water
- Control group: a Webril patch containing 0.4 ml of sterile water
- Site: posterior left flank
- Evaluation (hr after challenge): 24 and 48 according to the Dermal Irritation Grading System as described above


Challenge controls:
10 guinea pigs for challenge control and 10 guinea pigs for Rechallenge control group.
Positive control substance(s):
yes
Remarks:
dinitrochlorobenzene (DNCB)

Results and discussion

Positive control results:
Challenge with DNCB produced substantially stronger dermal responses, demonstrating that the test system could detect potential contact sensitizers.

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
25% in water
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 25% in water. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
25% in water
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 25% in water. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
rechallenge
Hours after challenge:
24
Group:
test chemical
Dose level:
25% in water
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: rechallenge. . Hours after challenge: 24.0. Group: test group. Dose level: 25% in water. No with. + reactions: 0.0. Total no. in groups: 10.0.

Any other information on results incl. tables

Minimal dermal irritation (grades 0 to ±) was observed in both the test and negative control animals at challenge (table 1) and rechallenge (data not shown). Group mean dermal scores were also comparable between groups.

Table 1: Responding animals versus total animals in the challenge.

 

Dermal score

24h

48h

Test 25%

+/-

18/20

4/20

Control 25%

+/-

8/10

2/10

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
Based on the results, the test substance is not considered a contact sensitizer in guinea pigs under the conditions of this test.
Executive summary:

A modified Buehler test was performed. 20 female animals were indiced by epidermal application of 0.4 ml (25% in water) of the test substance (3 times on 3 following weeks). 10 animals were included in the challenge control group and 10 in rechallenge control group. The positive control dinitrochlorobenzene (DNBC) was applied to 5 animals with additional 3 animals as DNBC challenge control.

Blood samples were collected before and after the test period. After each induction, test sites were scored for dermal irritation. Following a rest period of 14 days, animals were exposed to challenge dose.

A rechallenge was performed on the test and challenge control animals 7 days after the challenge procedure. The extent and degree of skin reaction to the challenge exposure in the test animals is compared with that demonstrated by control animals which undergo sham treatment during induction and receive the challenge exposure.

Based on the results, the test substance is not considered a contact sensitizer in guinea pigs under the conditions of this test.