Octabenzone

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10.9.1991 to 5.12.1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

1981 followed, reliability scoring based on 1992 guideline

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

84/449/EEC

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

A valid Guinea Pig Maximization Test (GPMT) is available with the test item and therefore no LLNA is required.

Test material

Test material information

Constituent 1

Reference substance name:

Octabenzone

EC Number:

217-421-2

EC Name:

Octabenzone

Cas Number:

1843-05-6

Molecular formula:

C21H26O3

IUPAC Name:

[2-hydroxy-4-(octyloxy)phenyl](phenyl)methanone

In vivo test system

Test animals

Species:

guinea pig

Strain:

other: Pirbright White (Tif: DHP)

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: CIBA-GEIGY Limited (Animal Production) 4332 Stein/Switzerland
- Age at study initiation: Not reported
- Weight at study initiation: 351 to 414 g
- Housing: individually in Macrolon cages (Type 3)
- Diet: standard guinea pig pellets-NAFAG No. 845, Gossau G, ad libitum
- Water: fresh water, ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 30 to 70
- Air changes (per hr): Not reported
- Photoperiod (hrs dark / hrs light): 12 hrs dark/12 hrs light

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal

Vehicle:

other: Oleum arachidis and vaseline

Concentration / amount:

5%

Induction 2

Route:

epicutaneous, occlusive

Vehicle:

other: vaseline

Concentration / amount:

30%

Day(s)/duration:

48h

Challenge

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

other: vaseline

Concentration / amount:

20%

No. of animals per dose:

Test group: 10/sex
Control group: 5/sex

Details on study design:

RANGE FINDING TESTS:
The concentration used for intradermal injections (5% test material in Oleum arachidis) was selected based on the solubility of the test article in standard vehicles and its local systemic tolerability. The concentration used for epidermal applications was selected based on the primary irritation potential of the test article. The maximum subirritant concentration of test material was determined by testing 1, 5, 10, and 30% test material in vaseline in a separate group of animals. Since none of the concentrations induced erythema, the highest concentration (30% in vaseline) was used for epidermal induction. To minimize non-specific reactions in adjuvant-treated animals, a concentration of 20% of test material in vaseline was used for epidermal challenge.

MAIN STUDY:
Control group: one side of flank induced with vehicle and challenged with vehicle; other side of flank induced with vehicle and challenged with test substance
Test group: one side of flank induced with test substance and challenged with vehicle; other side of flank induced with test substance and challenged with test substance

A. INDUCTION EXPOSURE
- No. of exposures: 2
- Exposure period: single exposure (intradermal), 48 hours (epidermal)
- Test groups:
FIRST INDUCTION WEEK, INTRADERMAL INJECTION Three pairs of intradermal injections (0.1 ml per injection) were made simultaneously into the shaved neck of guinea pigs as follows:
-adjuvant/saline mixture 1:1 (v/v)
-test article in Oleum arachidis (w/v)
-test article in the adjuvant/saline mixture (w/v)
SECOND INDUCTION WEEK, EPIDERMAL APPLICATION
In the second week of induction, test material was incorporated into vaseline (w/w) and applied on a filter paper patch to the neck of the animals (patch 2x4 cm; approx. 0.4 g paste per patch; occluded administration for 48 hours).
- Control group: 10 animals (5 m/5 f) were treated with adjuvant and the vehicle during the induction period
- Site: intradermal injection into the shaved neck region, followed by closed-patch exposure over the injection sites
- Frequency of applications: single-dose exposures (intradermal injection in the first week and epidermal application in the second week)
- Duration: 0-8 days
- Concentrations: 5% in vehicle (intradermal) and 30% in vaseline (epidermal)

INDUCTION REACTIONS: after intradermal and epidermal induction, irritant reactions are normally induced by the adjuvant, the high test article concentration, or the sodium lauryl sulfate pretreatment. Because most of the reactions are treatment-related rather than compound-related, such reactions are only described in special cases.

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: animals were challenged at Week 5.
- Exposure period: 24 hours
- Test groups: animals were tested on the flank with 20% test material in vaseline (w/w) or the vehicle alone (patch 2x2 cm; approx. 0.2 g paste per patch; occluded administration).
- Control group: animals were treated with the vehicle as well as with the test article to check the maximum subirritant concentration of the test article in adjuvant-treated animals.
- Site: flank
- Concentrations: 20% in vaseline (epidermal challenge)
- Evaluation (hr after challenge): 24 and 48 hrs

CHALLENGE REACTIONS: 24 and 48 hours after removing the dressings, the challenge reactions were graded according to the Draize scoring scale (Appraisals of the Safety of chemicals in Foods, Drugs and Cosmetics (1959), The US Association of Food and Drug Officials (AFDO).

The sensitising potential of the test material was classified according to the grading of Magnusson and Kligman.Maximisation grading:
Sensitisation rate (%) - Grade - Classification
(0-8) - I - weak(9-28) - II - mild
(29-64) - III - moderate
(65-80) - IV - strong
(81-100) - V - extreme

POSITIVE CONTROL TEST:
The sensitivity of the strain is checked by the laboratory every six months with a known sensitiser, such as 2,4-dinitrochlorobenzene, paraphenylene-diamine, or potassium dichromate.The results of the latest positive control test conducted from June 17, 1991 to July 18, 1991 using 1-chlor-2,4-dinitrobenzol were provided. The following concentrations were used: 0.1% in Oleum arachidis for intradermal induction, 1% in vaseline for epidermal induction, and 0.1% in vaseline for epidermal challenge. Induction and challenge procedures, including the scoring scale (Magnusson and Kligman) were as described for the main study.

Challenge controls:

During the challenge period, the group was treated with the vehicle as well as with the test article to check the maximum subirritant concentration of the test article in adjuvant-treated animals.

Positive control substance(s):

yes

Remarks:

1-chlor-2,4-dinitrobenzol

Study design: in vivo (LLNA)

Statistics:

Statistical analysis was not performed.

Results and discussion

Positive control results:

The number of animals with a positive reaction after occlusive epidermal application (induced with sensitiser and challenged with sensitiser) was 10/10 at both 24 and 48 hours. The sensitivity of the strain is checked every six months with a known sensitiser, such as 2,4-dinitrochlorobenzene, paraphenylene-diamine, or potassium dichromate. The results of the latest positive control test was provided using 1-chloro-2,4-dintrobenzol.

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

20%

No. with + reactions:

13

Total no. in group:

20

Clinical observations:

11 very slight erythema; 1 very slight erythema + edema; 1 well defined erythema

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

20%

No. with + reactions:

12

Total no. in group:

20

Clinical observations:

12 very slight erythema

Results 3

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

20%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

20%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Applicant's summary and conclusion

Interpretation of results:

Category 1B (indication of skin sensitising potential) based on GHS criteria

Conclusions:

65% and 60% of the animals were sensitised the test item under the experimental conditions employed 24 and 4 8 hours after challenge, respectively.

Executive summary:

The sensitization ptential of the test article was investigated in a GLP-compliant guinea-pig maximization study following OECD guideline 406. The induction was a two-stage operation. First, intradermal injections (into the neck region); second, closed patch exposure over the injection sites one week later. The concentration for the intradermal injections (5%) was selected on account of the solubility of the test article in standard vehicles and its local and systemic tolerability. Three pairs of intradermal injections (0.1 ml per injection) were made simultaneously into the shaved neck of the guinea with adjuvant/saline mixture 1:1, with the test article in Oleum arachidis, and with the test article in the adjuvant saline mixture. In the second week the test item was incorporated in vaseline (w/w) and applied on a filterpaper patch to the neck of the animals for 48 hours. The concentrations for the epidermal applications were selected on account of the primary irritation potential. Since at 30% no erythema reactions were seen, this concentration was used for the epidermal induction. Two weeks after the induction the animals were tested on the flank with the test item at 20% in vaseline and the vehicle alone for 24 hours. A control group of 10 animals (5 m/5 f) was treated with adjuvant and the vehicle during the induction period. Twenty four and forty eight hours after removing the dressings, the challenge reactions were graded according to the Draize scoring scale. Under the experimental conditions employed, 65 and 60% of the animals of the test group showed skin reactions 24 and 48 hours after removing the dressings, respectively. The test item is therefore classified as a sensitiser in albino guinea pigs.