2,4-dimethyl-6-(1-methyl-pentadecyl)phenol

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

01.10.1991 - 27.01.1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: OECD guideline study, GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

adopted May 12, 1981

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Species:

guinea pig

Strain:

other: Pirbright white

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Ciba-Geigy Ltd., Animal Production, 4332 Stein, Switzerland
- Age at study initiation: approx. 10 weeks old
- Weight at study initiation: 345-420 g
- Housing: individually in Macrolon cages
- Diet: standard guinea pig pellets - NAFAG No. 845, Gossau SG - ad libitum
- Water: fresh water, ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature: 22 ± 3 °C
- Humidity: 30-70 %
- Photoperiod: 12 hours dark/12 hours light

IN-LIFE DATES: from 12-November to 19-December 1991

Route:

intradermal and epicutaneous

Vehicle:

other: Intradermal applic.: arachis oil; epidermal applic.: vaseline (soft white petrolatum)

Concentration / amount:

Induction:
Intradermal application: the concentration was selected on account of the solubility of the test substance in standard vehicles.
Concentration: 5 %
Vehicle: arachidis oil
Epidermal application: the concentration was selected on account of the primary irritation potential of the test substance.
Concentration: 30 %
Vehicle: vaseline

Challenge:
Epidermal application: the concentration was selected on account of the primary irritation potential of the test substance.
Concentration: 10 % (first challenge)
Concentration: 5 % (second challenge)
Vehicle: vaseline.

Route:

epicutaneous, semiocclusive

Vehicle:

other: Intradermal applic.: arachis oil; epidermal applic.: vaseline (soft white petrolatum)

Concentration / amount:

Induction:
Intradermal application: the concentration was selected on account of the solubility of the test substance in standard vehicles.
Concentration: 5 %
Vehicle: arachidis oil
Epidermal application: the concentration was selected on account of the primary irritation potential of the test substance.
Concentration: 30 %
Vehicle: vaseline

Challenge:
Epidermal application: the concentration was selected on account of the primary irritation potential of the test substance.
Concentration: 10 % (first challenge)
Concentration: 5 % (second challenge)
Vehicle: vaseline.

No. of animals per dose:

The test was performed on 10 male and 10 female guinea pigs in the test group and 5 males and 5 females in the control group

Details on study design:

A. INDUCTION EXPOSURE
First induction week (intradermal application): Three pairs of intradermal injections (0.1 mL per injection) were made simultaneously into the shaved neck of the guinea pigs as follows:
- adjuvant/saline mixture 1:1 (v/v)
- test substance in oleum arachidis (w/v)
- test substance in the adjuvant saline mixture (w/v)

Second induction week (epidermal application): the test substance was incorporated in vaseline (w/w) and applied on a filterpaper patch to the neck of the animals (patch 2x4 cm; approx. 0.4 g paste per patch; occluded administration for 48 hours).

- Control group: A control group was treated with adjuvant and the vehicle during the induction period.
- Site: neck region

B. CHALLENGE EXPOSURE (week 5)
The animals (10 males and 10 females) were tested on the flank with the test substance in vaseline (w/w) and the vehicle alone (patch 2x2 cm; approx. 0.2 g paste per patch; occluded administration for 24 hours). Twenty four and forty eight hours after removing the dressings, the challenge reactions were graded according to the Draize scoring scale.
- Control group: During the challenge period the group was treated with the vehicle as well as with the test article (at least 10 animals) to check the maximum subirritant concentration of the test article in adjuvant treated animals.

C. RECHALLENGE (week 6)
In attempt to get more clear-cut results, a second challenge application with the animals of the test group was performed.

Challenge controls:

10 males and 10 females

Positive control substance(s):

yes

Remarks:

The sensitivity of the strain is checked every six months with a known sensitiser. The results of the latest positive control test (1-Chlor-2,4-dinitrobenzene) are presented in the report.

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

10 % test substance in vaseline

No. with + reactions:

8

Total no. in group:

20

Clinical observations:

Immediately after this challenge application the animals of the test group showed strong stress responses.

Remarks on result:

other: see Remark

Remarks:

Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 10 % test substance in vaseline . No with. + reactions: 8.0. Total no. in groups: 20.0. Clinical observations: Immediately after this challenge application the animals of the test group showed strong stress responses..

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

10 % test substance in vaseline

No. with + reactions:

11

Total no. in group:

20

Clinical observations:

Immediately after this challenge application the animals of the test group showed strong stress responses.

Remarks on result:

other: see Remark

Remarks:

Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 10 % test substance in vaseline . No with. + reactions: 11.0. Total no. in groups: 20.0. Clinical observations: Immediately after this challenge application the animals of the test group showed strong stress responses..

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

10 % test substance in vaseline

No. with + reactions:

3

Total no. in group:

10

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 10 % test substance in vaseline . No with. + reactions: 3.0. Total no. in groups: 10.0.

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

10 % test substance in vaseline

No. with + reactions:

2

Total no. in group:

10

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 10 % test substance in vaseline . No with. + reactions: 2.0. Total no. in groups: 10.0.

Reading:

rechallenge

Hours after challenge:

24

Group:

test chemical

Dose level:

5 % test substance in vaseline

No. with + reactions:

12

Total no. in group:

20

Remarks on result:

other: Reading: rechallenge. . Hours after challenge: 24.0. Group: test group. Dose level: 5 % test substance in vaseline . No with. + reactions: 12.0. Total no. in groups: 20.0.

Reading:

rechallenge

Hours after challenge:

48

Group:

test chemical

Dose level:

5 % test substance in vaseline

No. with + reactions:

11

Total no. in group:

20

Remarks on result:

other: Reading: rechallenge. . Hours after challenge: 48.0. Group: test group. Dose level: 5 % test substance in vaseline . No with. + reactions: 11.0. Total no. in groups: 20.0.

Interpretation of results:

sensitising

Remarks:

Migrated information

Conclusions:

40 and 55% of the animals were sensitised by the test item under the experimental conditions employed. After a second challenge application
60 and 55% of the animals were sensitised 24 and 48 hours after challenge, respectively. According to the maximisation grading the test article showed a moderate grade of skin-sensitising (contact allergenic) potential in albinoguinea pigs.

Executive summary:

The dermal sensitization potential of the test substance was assessed in a guinea pig maximization test with ten animals per sex according to OECD guideline 406 and in compliance with GLP. Test substance concentrations were based on account of the solubility of the test article in standard vehicles and its local and systemic tolerability (intradermal concentration) and on account of the primary irritation potential (epidermal concentrations). Induction was a two-stage operation. First, three pairs of intradermal injections (0.1 mL/site) were made simultaneously into the shaved neck of the guinea pigs as follows:

A) A 1:1 v/v mixture of Freund’s Complete Adjuvant with saline

B) The test substance at a 5% concentration on oleum arachidis (w/v)

C) Test article in the adjuvant saline mixture (w/v)

One week later, the test article at a concentration of 30% in vaseline was applied occlusively on a filterpaper patch to the neck of the animals for 48 hours (patch 2x4 cm; approx. 0.4 g paste per patch). Two weeks after the epidermal application all animals were challenged on the flank with a 10% test substance concentration in vaseline and the vehicle alone for 24 hours (patch 2x2 cm; approx. 0.2 g paste per patch; occluded administration). A control group of 10 animals (5 m/5 f) was treated with adjuvant and the vehicle during the induction period. 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. In attempt to get more clear-cut results, a second challenge application with the animals of the test group was performed (5% test item concentration). Skin reactions were assessed 24 and 48 hours after the removal of the challenge patches according to the Draize scoring scale. 40 and 55% of the animals were sensitised by the test item under the experimental conditions employed. After the second challenge application, 60 and 55% of the animals were sensitised 24 and 48 hours after challenge, respectively. According to the maximisation grading the test article showed a moderate grade of skin-sensitising (contact allergenic) potential in albinoguinea pigs. Based on these results the test item required classification for skin sensitization.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

The test substance was investigated for its sensitizing potential in a Maximization test according to OECD guideline 406 and under GLP requirements (CIBA-GEIGY, 1992). Pirbright White guinea pigs received two intradermal induction treatments with 5% in arachis oil and one epicutanous induction treatment with 30% in vaseline. For each injection, three pairs (adjuvant/saline; test item in vehicle; test item in vehicle plus adjuvant/saline) were given. Control animals were treated equally with test substance replaced by the vehicle. Epidermal challenge was performed by occlusive application for 24 h two weeks later (10% in vaseline). A second challenge was performed with 5% test item in vaseline. Skin reactions were assessed 24 and 48 hours after the removal of the challenge patches according to the Draize scoring scale. 40 and 55% of the animals were sensitised by the test item under the experimental conditions employed. After the second challenge application, 60 and 55% of the animals were sensitised 24 and 48 hours after challenge, respectively. In conclusion, the test substance is considered to be a skin sensitizer in albino guinea pigs and requires classification.

Migrated from Short description of key information:
The test item was found to have skin sensitizing properties in a Guinea Pig Maximization Test. No data on respiratory sensitization are available.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Dangerous Substance Directive (67/548/EEC)

The available experimental test data is reliable and suitable for the purpose of classification under Directive 67/548/EEC. Based on the present data, classification for sensitization is warranted under Directive 67/548/EEC (R43).

 

Classification, Labeling, and Packaging Regulation (EC) No. 1272/2008

The available experimental test data are reliable and suitable for the purpose of classification under Regulation (EC) No.1272/2008. Based on the present data, classification for sensitization is warranted under Regulation (EC) No.1272/2008 (GHS Cat 1B).