4-methylpentan-2-ol

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Report date:

1997

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

1992

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Test material

Test material information

Constituent 1

Reference substance name:

4-methylpentan-2-ol

EC Number:

203-551-7

EC Name:

4-methylpentan-2-ol

Cas Number:

108-11-2

Molecular formula:

C6H14O

IUPAC Name:

4-methylpentan-2-ol

Details on test material:

- Name of test material (as cited in study report): METHYL ISOBUTYL CARBINOL.
- Physical state: Colourless liquid.
- Analytical purity: 99.04%.
- Lot/batch No.: 9609P0519.
- Expiration date of the lot/batch: October 1997.
- Stability under test conditions: Not reported.
- Storage condition of test material: At room temperature and protected from light.

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Centre d'Elevage Lebeau, 78950 Gambais, France.
- Age at study initiation: Approximately 3 months old.
- Weight at study initiation: 357 ± 26 g (males); 366 ± 23 g (females).
- Housing: Housed individually in polycarbonate cages.
- Diet (e.g. ad libitum): 106 pelleted diet (U.A.R., 91360 Villemoisson-sur-Orge, France), ad libitum.
- Water (e.g. ad libitum): Drinking water was filtered by a F.G. Millipore membrane (0.22 micron) was provided ad libitum.
- Acclimation period: At least 5 days before the beginning of the study.


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 ± 2 °C.
- Humidity (%): 30 to 70%.
- Air changes (per hr): 12 per hr.
- Photoperiod (hrs dark / hrs light): 12 hr dark / 12 hr light.

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

other: See details under study design

Induction 2

Concentration / amount:

-Intradermal induction: 1% (w/w) in paraffin oil.
-Cutaneous induction: Undiluted.
-Cutaneous challenge: Undiluted.

II) Challenge period
-application of 0.5 mL of the test substance, undiluted.

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

other: See details under study design

Challenge 2

Concentration / amount:

-Intradermal induction: 1% (w/w) in paraffin oil.
-Cutaneous induction: Undiluted.
-Cutaneous challenge: Undiluted.

II) Challenge period
-application of 0.5 mL of the test substance, undiluted.

No. of animals per dose:

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

Details on study design:

RANGE FINDING TESTS: A preliminary test was conducted in order to determine the concentrations to be tested in the main study.

Preparation of the animals:
For all animals and before each treatment, the application sites were:
-clipped on Days -1 and 7 (scapular area 4 cm x 2 cm),
-clipped and shaved on Day 21 (each flank 2 cm x 2 cm).

I) Induction phase by intradermal and cutaneous routes

1) Intradermal route
On Day 1, six injections were made deep into the dermis of a clipped area (4 cm x 2 cm) in the dorsal region between the shoulders, using a needle mounted on a 1 mL glass syringe.

Three injections of 0.1 mL were made into each side of this shoulder region, as follows:
Treatment group:
A) Anterior: Freund's complete adjuvant diluted at 50% (v/v) with 0.9% NaCl
B) Middle: test substance at 1% (w/w) in paraffin oil
C) Posterior: mixture of 50/50 (w/v) of A and B

Control group:
A) Anterior: Freund's complete adjuvant diluted at 50% (v/v) with 0.9% NaCl
B) Middle: vehicle (paraffin oil)
C) Posterior: mixture of 50/50 (w/v) of A and B

2) Cutaneous route
On Day 7, the scapular area was clipped. As the test substance was shown to be non-irritant during the preliminary tests, the animals were treated with 0.5 mL of sodium lauryl sulfate (10% w/w) in vaseline in order to induce local irritation.

On Day 8, a topical application to the region of the intradermal injection was performed.

Control group:
Application of 0.5 mL of the vehicle

Treatment group:
Application of 0.5 mL of the test substance undiluted.

The test substance and the vehicle were prepared on a dry gauze pad, which was then applied to the dorsal region between the shoulders and held in place for 48 hours by means of an adhesive hypoallergenic dressing and an adhesive anallergenic waterproof plaster. No residual test substance was observed after removal of the dressing. Cutaneous reactions were recorded one hour after removal of the occlusive dressing.

II) Challenge phase
On Day 22, the animals from both groups received an application of 0.5 mL of the test substance undiluted to the posterior right flank, and 0.5 mL of the vehicle to the posterior left flank. This application was performed using a 1 mL glass syringe. The test substance and the vehicle were prepared on a dry gauze pad, then applied to a 4 square cm clipped area of the skin. The gauze pad was held in contact with the skin for 24 hours by means of occlusive, hypoallergenic dressing and an adhesive anallergenic waterproof plaster. No residual test substance was observed after removal of the dressing.

Twenty-four and 48 hours after the challenge application, both flanks of the treated and control animals were observed in order to evaluate cutaneous reactions, according to the following scale:

Erythema and eschar formation: Grade
No erythema: 0
Very slight erythema (barely perceptible): 1
Well-defined erythema: 2
Moderate to severe erythema: 3
Severe erythema (beet redness) to slight eschar formation (injuries in depth): 4

Oedema: Grade
No oedema: 0
Very slight oedema (barely perceptible): 1
Slight oedema (visible swelling with well-defined edges): 2
Moderate oedema (visible swelling raised more than 1 mm): 3
Severe oedema (visible swelling raised more than 1 mm and extending beyond the area of exposure): 4

Any other lesions were noted.

Clinical examinations: The animals were observed twice a day during the study in order to check for clinical signs and mortality.

Body weight: The animals were weighed individually on the day of allocation into the groups, on the first day of the study (Day 1), on Days 8 and 15 and on the last day of the study (Day 25).

Macroscopic examination of the main organs was performed on the animal found dead during the study. At the end of the study, all the animals were killed and no necropsy was performed.

Challenge controls:

See details on study design.

Positive control substance(s):

yes

Remarks:

2,4-Dinitro chlorobenzene

Results and discussion

Positive control results:

Positive control: Under the experimental conditions and according to the Magnusson and Kligman method, the test substance 2,4-dinitro chlorobenzene at a concentration of 0.5% (w/w) induced positive skin sensitization reactions in 50% of the guinea-pigs. 

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

Undliuted

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

No cutaneous reactions were observed

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: Undliuted. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: No cutaneous reactions were observed.

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

Undiluted

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

No cutaneous reactions were observed

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: Undiluted. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: No cutaneous reactions were observed.

Results 3

Reading:

other: 1st reading: right flank

Hours after challenge:

24

Group:

negative control

Dose level:

Undiluted

No. with + reactions:

0

Total no. in group:

9

Clinical observations:

No cutaneous reactions were observed; 1 animal died on Day 8 - death was not attributed to treatment

Remarks on result:

other: see Remark

Remarks:

Reading: other: 1st reading: right flank. . Hours after challenge: 24.0. Group: negative control. Dose level: Undiluted. No with. + reactions: 0.0. Total no. in groups: 9.0. Clinical observations: No cutaneous reactions were observed; 1 animal died on Day 8 - death was not attributed to treatment.

Results 4

Reading:

other: 2nd reading: right flank

Hours after challenge:

48

Group:

negative control

Dose level:

Undiluted

No. with + reactions:

0

Total no. in group:

9

Clinical observations:

No cutaneous reactions were observed; 1 animal died on Day 8 - death was not attributed to treatment

Remarks on result:

other: see Remark

Remarks:

Reading: other: 2nd reading: right flank. . Hours after challenge: 48.0. Group: negative control. Dose level: Undiluted. No with. + reactions: 0.0. Total no. in groups: 9.0. Clinical observations: No cutaneous reactions were observed; 1 animal died on Day 8 - death was not attributed to treatment.

Results 5

Reading:

other: 1st reading: left flank

Hours after challenge:

24

Group:

negative control

Dose level:

Paraffin oil

No. with + reactions:

0

Total no. in group:

9

Clinical observations:

No cutaneous reactions were observed; 1 animal died on Day 8 - death was not attributed to treatment

Remarks on result:

other: see Remark

Remarks:

Reading: other: 1st reading: left flank. . Hours after challenge: 24.0. Group: negative control. Dose level: Paraffin oil. No with. + reactions: 0.0. Total no. in groups: 9.0. Clinical observations: No cutaneous reactions were observed; 1 animal died on Day 8 - death was not attributed to treatment.

Results 6

Reading:

other: 2nd reading: left flank

Hours after challenge:

48

Group:

negative control

Dose level:

Paraffin oil

No. with + reactions:

0

Total no. in group:

9

Clinical observations:

No cutaneous reactions were observed; 1 animal died on Day 8 - death was not attributed to treatment

Remarks on result:

other: see Remark

Remarks:

Reading: other: 2nd reading: left flank. . Hours after challenge: 48.0. Group: negative control. Dose level: Paraffin oil. No with. + reactions: 0.0. Total no. in groups: 9.0. Clinical observations: No cutaneous reactions were observed; 1 animal died on Day 8 - death was not attributed to treatment.

Any other information on results incl. tables

Clinical examinations: Hypoactivity and piloerection were observed on Day 7 in one animal of the control group; it was found dead on Day 8. Such spontaneous clinical signs and mortality are sometimes observed in this species; they were not attributed to treatment. 

No clinical signs and no mortalities were noted in the remaining animals. The body weight gain of the treated animals was normal when compared to that of the control animals.

 

Scoring of cutaneous reactions:

1) End of induction period: On Day 10, after topical application of the induction period, signs of irritation were observed at the test site (dorsal region between shoulders) in the control and treated groups.

2) Challenge application: No residual test substance was observed after removal of the dressing. 

 

Necropsy: Macroscopic examination of the main organs of the animal found dead during the study revealed no abnormalities. No microscopic examinations were performed. 

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information

Conclusions:

Under the experimental conditions and according to the maximization method of Magnusson and Kligman, no cutaneous reactions attributable to the sensitization potential of the test substance were observed in guinea-pigs.

Executive summary:

The skin sensitization potential of methyl iso butyl carbinol was assessed in a study performed according to OECD Guidelines for the Testing of Chemicals No. 406 and in compliance with GLP in male and female Dunkin-Hartley guinea pigs.  In the main study, 10 animals/sex comprised the methyl iso butyl carbinol test group and 5 animals/sex comprised the vehicle control group.  The intradermal induction was carried out with 0.1 mL of 1% (w/w) of methyl iso butyl carbinol in vehicle (paraffin oil), and epicutaneous induction was performed with 0.5 mL of undiluted methyl iso butyl carbinol to the dorsal area under occlusive conditions.  The challenge exposure also was conducted with 0.5 mL of undiluted methyl iso butyl carbinol.  Additionally, all animals were dermally exposed to 0.5 mL of 10% w/w sodium lauryl sulphate (SDS) in vaseline 24 hours prior to topical sensitization of the skin area in order to induce local irritation (methyl iso butyl carbinol was shown to be non-irritating in the preliminary test).  Skin reactions were observed and recorded 1 hour after dermal and 24 and 48 hours after the challenge exposure, all according to the grading scale by Magnusson and Kligman.  Hypoactivity and piloerection were observed on Day 7 in one animal of the control group and it was found dead on Day 8. Macroscopic examination of the main organs of the animal found dead revealed no abnormalities and the authors determined that these findings were not attributed to treatment. Other control animals and test animals displayed normal body weight gain throughout the investigation and no mortalities or clinical signs were observed in these animals.  Under the experimental conditions and according to the maximization method of Magnusson and Kligman, no cutaneous reactions attributable to the sensitization potential of methyl iso butyl carbinol were observed in guinea-pigs.  Therefore, the results of this study demonstrated that methyl iso butyl carbinol showed no evidence of contact skin sensitization in guinea pigs.