Cyclohexylbenzene

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well documented GLP study according to international guideline.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

adopted 17 July 1992

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

GLP compliance:

yes (incl. QA statement)

Type of study:

guinea pig maximisation test

Test material

Test material information

Constituent 1

Reference substance name:

Cyclohexylbenzene

EC Number:

212-572-0

EC Name:

Cyclohexylbenzene

Cas Number:

827-52-1

Molecular formula:

C12H16

IUPAC Name:

cyclohexylbenzene

Details on test material:

- Name of test material (as cited in study report): MCS-2805
- Lot No.: ABDR-016
- Description: clear colourless liquid
- Composition: cyclohexylbenzene: 92.6%; bicyclohexyl: 6.9%
- Date received: 2001-08-06
- Storage conditions: room temperature, in the dark

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: David Hall Limited, Burton-on-Trent, Staffordshire, UK
- Age at study initiation: approximately 8-12 weeks
- Weight at study initiation: 323-451g
- Housing: singly or in pairs in solid-floor polypropylene cages furnished with woodflakes
- Diet: ad libitum (Certified Guinea Pig Diet (Code 5026) supplied by PMI Nutrition International, Nottingham, UK)
- Water: ad libitum
- Acclimation period: ≥ 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17-23 °C
- Humidity (%): 30-70
- Air changes (per hr): ≥ 15
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

arachis oil

Induction 2

Concentration / amount:

Concentrations as used in the main study:
- Intradermal injections: 5% v/v in arachis oil BP
- Topical induction: 100% (undiluted)
- Topical challenge: 75% v/v in arachis oil BP

Challenge

Challenge 1

Route:

epicutaneous, semiocclusive

Vehicle:

arachis oil

Challenge 2

Concentration / amount:

Concentrations as used in the main study:
- Intradermal injections: 5% v/v in arachis oil BP
- Topical induction: 100% (undiluted)
- Topical challenge: 75% v/v in arachis oil BP

Details on study design:

RANGE FINDING TESTS: The concentrations of test material to be used at each stage of the main study were determined by "sighting tests" in which groups of guinea pigs were treated with various concentrations of test material.

Sighting test -- Intradermal induction:
Intradermal injections (0.1 ml/injection site) were made on the clipped shoulder of two guinea pigs, using concentrations of 1% and 5% v/v in arachis oil BP. The degree of erythema at the injection sites was assessed approximately 24, 48, 72 hours and 7 days after injection. The degree of oedema was not evaluated. Any evidence of systemic toxicity was also recorded. The highest concentration that caused only mild to moderate skin irritation, an which was well tolerated systemically, was selected for the intradermal induction stage of the main study.

Sighting test -- Topical induction:
Two guinea pigs (intradermally injected with Freund’s Complete Adjuvant fifteen days earlier) were treated with undiluted test material and 3 preparations of the test material (75%, 50% and 25% v/v in arachis oil BP). Applications were made to the clipped flanks under occlusive dressings for an exposure period of 48 hours. The degree of erythema and oedema was evaluated approx. 1, 24 and 48 hours after dressing removal. The highest concentration producing only mild to moderate dermal irritation was selected for the topical induction stage of the main study.

Sighting test -- Topical challenge:
The undiluted test material and 3 preparations of the test material (75%, 50% and 25% v/v in arachis oil BP) were applied to clipped flanks of two guinea pigs under occlusive dressings for an exposure period of 24 hours. These guinea pigs did not form part of the main study but had been treated identically to the control animals of the main study up to day 14. The degree of erythema and oedema was evaluated approx. 1, 24 and 48 hours after dressing removal. The highest non-irritant concentration of the test material and one lower concentration were selected for the topical challenge of the main study.


MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (intradermal injection (day 0) and topical application (day 7))
- Exposure period: topical application: 48 h
- Control group: intradermal and topical induction procedure was identical to that used for the test animals except that the test material was omitted
- Site: shoulder region
- Concentrations: intradermal injection: (a) Freund's Complete Adjuvant plus distilled water in the ration 1:1 (b) a 5% v/v formulation of test material in arachis oil BP (c) 5% v/v formulation of test material in 1:1 preparation of Freud's Complete Adjuvant plus distilled water

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: 21
- Exposure period: 24 h
- Site: right (undiluted) and left (75% v/v in arachis oil BP) flank
- Evaluation (hr after challenge): 24 and 48

Positive control substance(s):

no

Remarks:

No concurrent positive control but summary of historical positive control data was present (1998-2001)

Results and discussion

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

all dose levels

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: all dose levels. 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:

all dose levels

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: all dose levels. No with. + reactions: 0.0. Total no. in groups: 20.0.

Results 3

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

all dose levels

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: all dose levels. No with. + reactions: 0.0. Total no. in groups: 10.0.

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

all dose levels

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: all dose levels. No with. + reactions: 0.0. Total no. in groups: 10.0.

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Under the conditions of the test, the test material produced a 0% (0/20) sensitisation rate and was classified as a non-sensitiser to guinea pig skin.

Executive summary:

The study was performed to assess the contact sensitisation potential of the test material in the albino guinea pig.

20 test and 10 control animals were used for the study. 2 phases were involved in the main study: an induction of a response by intradermal injection and topical application and a topical challenge of that response.

Under the conditions of the test, the test material produced a 0% (0/20) sensitisation rate and was classified as a non-sensitiser to guinea pig skin.