2,4,6-trimethylphenol

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other: GLP compliant guideline study, available as unpublished report, no restrictions, fully adequate for assessment.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: Dermatotoxicology, F.N. Marzulli and H.I. Maibach, editors, 4th edition, 1991, pages 374-378, Hemisphere Publishing Corporation, New York.

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: Magnusson B. and Kligman A.M. (1969). The identification of contact allergens by animal assay. The guinea pig maximisation test. J. Invest. Dermatol., 52, 268

GLP compliance:

yes

Type of study:

Buehler test

Justification for non-LLNA method:

Application of REACH Annex XI sect. 1.1.2 criteria. Data available by letter of access.

Test material

Test material information

Constituent 1

Reference substance name:

2,4,6-trimethylphenol

EC Number:

208-419-2

EC Name:

2,4,6-trimethylphenol

Cas Number:

527-60-6

Molecular formula:

C9H12O

IUPAC Name:

2,4,6-trimethylphenol

Test material form:

other: powder or cake

Details on test material:

- Name of test material (as cited in study report): 2,4,6-Trimethyl phenol (TMP, Mesitol)
- Batch #: (Grade 8093)
- Description: White crystalline powder or cake
- Physical state: Solid
- Stability: Stability under normal storage and use conditions
- Storage: Room temperature (in hood preferably)
- Color: White

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Elm Hill Breeding Labs, Inc., Chelmsford, MA
- Age at study initiation: at least 21 days old (adult)
- Weight at study initiation: 377.8 – 434.1 g
- Housing: Group housed, suspended stainless steel cages; Bedding: Prochip, Harlan Teklad, Madison, WI (non-contact)
- Diet: TEK 8602 Guinea Pig Diet, Harlan Teklad, Madison, WI, ad libitum
- Water: Tap water, ad libitum
- Acclimation period: Minimum 5 days under the same conditions as for the actual test.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ± 3
- Humidity (%): 30 - 70
- Air changes (per hr): 10 to 15
- Photoperiod (hrs dark / hrs light): 12-hour light/dark cycle, full spectrum fluorescent lights

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

epicutaneous, occlusive

Vehicle:

other: 80% ethanol/water

Induction 2

Concentration / amount:

RANGE FINDING TEST: 10, 25, 50 and 100%
MAIN STUDY: Induction exposure and challange: 50%

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

other: 80% ethanol/water

Challenge 2

Concentration / amount:

RANGE FINDING TEST: 10, 25, 50 and 100%
MAIN STUDY: Induction exposure and challange: 50%

No. of animals per dose:

- Experimental group: 10 males, 10 females
- Negative control group: 5 males, 5 females
- Positive control group: 3 males, 2 females
- Preliminary irritation group: 1 male, 2 females

Details on study design:

RANGE FINDING TESTS:
Four different concentrations of the test substance were applied to the skin for 6 hours. The responses were scored 24 hours after the test substance application and the test substance was determined not to be an irritant at a concentration of 50%.

MAIN STUDY
A. INDUCTION EXPOSURE
- Before each application of the test or control substance, the animals were clipped and shaved or depilitated on the scapula region in an area of about 3 cm x 4 cm.
- No. of exposures: The test substance was applied once per week for 3 consecutive weeks (Days 0, 7, and 14).
- Exposure period: The patch was removed after 6 hours of exposure and any residual test substance was wiped off with a gauze pad.
- Site: Closed patches for the experimental group were prepared with the test substance and were applied directly to the skin and covered with a gauze pad of approximately 4 - 6 cm2.
- Concentrations: 50% of the test substance was used

B. CHALLENGE EXPOSURE
- On the day of the challenge, a 4 x 3 cm virgin skin site was shaved on the flanks of the experimental and control animals.
- The challenge test was performed on freshly clipped skin sites of test and naïve control animals in the same way as the 6-hour closed patch test of the induction phase.
- Day of challenge: Day 28
- Exposure period: 6 hours
- Concentrations: 50% of the test substance was used
- Evaluation: At approximately 21 hours after removal of the challenge dose, the area of the challenge was marked and the whole back shaved. Approximately three hours after shaving, the test site was examined for erythema and edema. The reaction was graded according to the Magnusson and Kligman Grading Scale for the Evaluation of Challenge Patch Test Reactions. Reading of the skin area was repeated at approximately 48 hours after removal of the challenge dose and the skin reactions were graded.

Challenge controls:

Negative control: During induction, the animals were not treated. The challenge was performed similar to the treated animals.
Positive control: During induction, the positive control substance (0.4 mL of 0.1% DNCB in acetone) was applied in the same manner as the test substance. For the challenge 0.1% DNCB in acetone was used to challenge the positive control animals.

Positive control substance(s):

yes

Remarks:

0.1% DNCB in acetone

Results and discussion

Positive control results:

100% reactivity was observed in the positive control group at challenge

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

50%

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: 50%. 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:

50%

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: 50%. 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:

50%

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: 50%. 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:

50%

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: 50%. No with. + reactions: 0.0. Total no. in groups: 10.0.

Results 5

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

0.1%

No. with + reactions:

5

Total no. in group:

5

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: positive control. Dose level: 0.1%. No with. + reactions: 5.0. Total no. in groups: 5.0.

Results 6

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

0.1%

No. with + reactions:

5

Total no. in group:

5

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: positive control. Dose level: 0.1%. No with. + reactions: 5.0. Total no. in groups: 5.0.

Any other information on results incl. tables

- Preliminary irritation trial: Irritation (erythema and edema) was absent from all sites treated with the test article concentrations of 50%, 25%, and 10% at the 24-hour observation point.

- Body weight: All animals gained weight during the course of the study.

- Clinical observations: No abnormal clinical observations were evident in any of the animals during the course of the preliminary irritation trial.

- All test animals showed no signs of erythema or edema at the 24- and 48-hour observation points for the challenge phase. No reactions were observed in the negative control group at challenge

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The test substance is not considered to be a skin sensitizer under the conditions of this study.

Executive summary:

2,4,6-Trimethyl Phenol (TMP, Mesitol) was evaluated for its potential to produce allergenic skin reactions in a GLP-compliant OECD 406 guideline study. 38 albino guinea pigs were selected for the study, of which twenty were treated with the test substance, ten were used as negative controls, five were used as positive controls and three were used in a preliminary irritation test. The concentrations of the test substance used in the main study were determined by the results of the preliminary irritation test. During the induction phase 50% of the test substance was applied once per week for 3 consecutive weeks (days 0, 7 and 14) on one side of the animal for 6 hours. The positive control substance (0.1% dinitrochlorobenzene, DNCB in acetone) was applied in the same manner. The negative controls received no treatment during the induction phase. The challenge test, on day 28, was performed on freshly clipped skin sites of test and naïve control animals with 50% of the test substance and 0.1% of the positive control substance for 6 hours to the positive control animals. 24 and 48 hours after removal of the challenge skin reactions were graded. No erythema and edema was observed in the test substance group and negative control group. 100% reactivity was observed in the positive control group. It can be concluded that the test substance shows no skin sensitizing potential in guinea pigs.