ε-caprolactam

Skin sensitisation

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

Test material information

Constituent 1

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)

Induction

Induction 1

Route:

epicutaneous, occlusive

Vehicle:

water

Induction 2

Concentration / amount:

0.4 ml of 25 % test substance in water for induction and challenge

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

water

Challenge 2

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)

Results

Results 1

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.

Results 2

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.

Results 3

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.