Hexahydro-2H-azepin-2-one, sodium salt

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

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:

Twenty female animals were induced by intra-dermal application to 0.1 ml (3 %) of the test substance with FCA, followed by epidermal application in the treatment group. 5 animals were included in the challenge 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.
Following a rest period of 14 days, animals were exposed to the challenge dose.
The extent and degree of skin reaction to the challenge exposure in the test animals was 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:

guinea pig maximisation test

Justification for non-LLNA method:

data already available

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

Details on test material:

- 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
- Storage condition of test material: room temperature

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): tap water
- Acclimation period: 5 days

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

Study design: in vivo (non-LLNA)

Induction

Route:

intradermal and epicutaneous

Vehicle:

water

Concentration / amount:

0.1 ml of 3 % test substance in water and 0.8 ml of 75% (w/v) test substance

Challenge

Route:

epicutaneous, occlusive

Vehicle:

water

Concentration / amount:

Challenge: 0.4 ml of 75 % (w/v) test substance in water

No. of animals per dose:

Test group: 20
Challenge control group: 5
Positive control group: 5
DNBC Challenge control group: 3

Details on study design:

1st application: Induction 3 % intracutaneous
2nd application: Induction 75 % occlusive epicutaneous
3rd application: Challenge 75 % occlusive epicutaneous

RANGE FINDING TESTS:
For the topical irritation screen, 4 concentrations (10, 25, 50 and 75% w/v in water, 4 animals/conc.) of Caprolactam were applied to the clipped skin of each animal under occlusive conditions. Approximately 24 hours after dosing, patches were removed from each animal and the test sites wiped with gauze moistened with distilled water. Approximately 21 hours later, the test sites were shaved (if necessary) and three hours thereafter, the test sites were graded for irritation according to the Dermal Irritation Grading System. The grading was repeated approximately 24 hours later (48 hour scores).

For the intra-dermal irritation screen, 4 concentrations (0.1, 1.0, 3.0 and 5.0% w/v in water, 4 animals/conc.) of Caprolactam were injected intradermally (0.1 ml/injection) to each animal. Approximately 24 and 48 hours later, the test sites were graded for irritation according to the Dermal Irritation Grading System as described for topical application:
0 - No reaction
± - Slight patchy erythema
1 - Slight but confluent or moderate patchy erythema
2 - Moderate confluent erythema
3- Severe erythema with or without edema

The results indicated that a test article concentration of 3.0 % w/v would be appropriate for the intradermal induction since it was the highest dose that did not produce excessive ulceration of the test sites. A 75% w/v concentration of Caprolactam was chosen for topical induction and challenge due to the minimal response noted at 24 hours post-dose and the complete resolution of the responses by 48 hours (see chapter 7.3.1 for details).

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (1x3 intra-dermal injection on day 1 and 1x topical application for 24 h on day 8)
- Test groups: On day 1, three pairs of intra-dermal injections were made in the clipped area of the study animals:
a. 0.1 ml of FCA/sterile water for injection, (1:1 v/v)
b. 0.1 ml of test article (3.0% w/v) in sterile water for injection,
c. 0.1 ml of test article (3.0% w/v) in FCA/sterile water for injection, (1:1 v/v)
On day 8, each animal received a patch consisting of 0.8 ml of the 75% w/v Caprolactam in sterile water over the intra-dermal site for 24 h under occlusive conditions.
- Challenge Control group: On day 1, three pairs of intra-dermal injections were made in the clipped area of the study animals:
a. 0.1 ml of FCA/sterile water for injection, (1:1 v/v)
b. 0.1 ml of sterile water for injection,
c. 0.1 ml of vehicle (3.0% w/v) in FCA/sterile water for injection, (1:1 v/v)
On day 8, each animal received a patch consisting of 0.8 ml of the sterile water over the intra-dermal site for 24 h under occlusive conditions.
- Site: scapular area

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- 14 day rest period
- Exposure period: 24 h
- Test groups: 0.4 ml of the 75% w/v Caprolactam in sterile water
- Control group: 0.4 ml of the sterile water
- Site: hip area
- Evaluation (hr after challenge): 24 and 48 according to the Dermal Irritation Grading System as described above

OTHER: 2 days ahead of application of the test substance and following the 48 hour scoring, a blood sample was obtained from each animal (orbital sinus) for evaluation of leukocyte and differential parameters. A second blood plasma sample was then obtained from the descending vena cava from 10 Caprolactam test animals (those showing the strongest dermal responses), the 5 Caprolactam controls and the 5 DNCB test animals for evaluation of plasma histamine.

Challenge controls:

5 guinea pigs

Positive control substance(s):

yes

Remarks:

dinitrochlorobenzene

Results and discussion

Positive control results:

Challenge with DNCB produced substantially stronger dermal responses in all animals previously induced with the positive control demonstrating that the test system could detect potential contact sensitizers. However, there were no differences in leukocyte, differential or plasma histamine data.

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

0.75 % in water

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

no indication of skin sensitisation

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

0.75 % in water

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

no indication of skin sensitisation

Any other information on results incl. tables

Following challenge with caprolactam, dermal responses in the test group consisted of grade ± reactions (13/20) and grade 1 reactions (7/20). Slight edema was also observed at 7/20 test sites at the 24 hours interval. By 48 hours, a grade 1 reaction was noted in 1/20 test animals (see table 1).

Dermal responses in challenge control group animals consisted of a grade 1 reaction (with slight edema) in 1/5 animals at 24 hours and of grade ± to 0 responses at all other control sites during the scoring intervals. The skin effects in the control group animals after challenge treatment are an indication of an irritation reaction to the used test concentration.

Challenge with DNCB produced substancially stronger dermal responses in all DNCB-induced animals.

No differences were observed between the challenge control and Caprolactam induced animals concerning leukocyte, differential or plasma histamine data. Evaluation of the tests regarding the skin sensitization potential is limited by using an irritant concentration for the challenge treatment. Based on the concurrent reaction in the control group animals and the fading of reactions from 24 to 48 hours, caprolactam is not considered to be a contact sensitizer under the test conditions chosen.

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

	Dermal score	24h	48h
Test 75%	+/-	13/20	14/20
	1	7/20	1/20
	slight edema	7/20	0/20
Control 75%	+/-	4/5	4/5
	1	1/5	0/5
	slight edema	1/5	0/0

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met