2-Butanone, peroxide

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:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Report date:

1999

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

17th July 1992

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

92/69/EEC; 31st July 1992

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The Guinea Pig Maximazitation Test (2005) met the previous requirements before the entry into force of REACH. The GPMT is suitable and reliable to cover this endpoint. For this reason and for animal welfare reasons, no further in vivo study (LLNA test) needs to be performed.

Test material

Test material information

Constituent 1

Reference substance name:

2-[(2-hydroperoxybutan-2-yl)peroxy]butane-2-peroxol; butane-2,2-diperoxol

EC Number:

700-954-4

Cas Number:

1338-23-4

Molecular formula:

Mixture of C4H10O4 and C8H18O6

IUPAC Name:

2-[(2-hydroperoxybutan-2-yl)peroxy]butane-2-peroxol; butane-2,2-diperoxol

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: breeder: Charles River France, 76410 Saint-Aubin-lès-Elbeuf; France
- Age at study initiation: approximately three months old (main study)
- Weight at study initiation: 390 ± 10 g for the males and 363 ± 13 g
- Diet (e.g. ad libitum): "106 pelleted diet" (UAR, 91360 Villemoissonsur-Orge, France); Food is analysed regularly by the supplier for composition and contaminant levels.
- Water (e.g. ad libitum): water fitered by a FG Milipore 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
- Humidity (%): 30 to 70
- Air changes (per hr): approximately 12 cycles/hour of filtered, non-recycled air
- Photoperiod (hrs dark / hrs light): 12 h/12 h

Study design: in vivo (non-LLNA)

Induction

Route:

intradermal and epicutaneous

Vehicle:

corn oil

Concentration / amount:

- Preliminary study: 0.1 to 10 % (intradermal); 5 - 100 % (cutaneous)
- Main study:
Induction (treated group): intradermal injections: test substance at the concentration of 0.1 % (w/w) in corn oil; topical application: test substance at the concentration of 10 % (w/w) in corn oil

Challenge

Route:

epicutaneous, occlusive

Vehicle:

corn oil

Concentration / amount:

First challenge (all groups): topical application: test substance at the concentration of 5 % (w/w) in corn oil
second challenge (all groups): topical application: test substance at the concentration of 1 % (w/w) in corn oil

No. of animals per dose:

- two males and two females for the preliminary test
- 30 animals (15 males and 15 females) for the main test; a control group I (five males and five females) and a treated group II (ten males and ten females)

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.
By intradermal route:
- 24 hours before trtreatment, the dorsol region of the animals was clipped
- intradermal administrations of the test substance formulation (0.1 mL) at different concentrations were preformed in the interscapular region
- cutaneous reactions were evaluated approximately 24, 48 hours and 6 days after the injections
By cutaneous route:
- 24 hours before treatment, both flank regions of the animals were clipped,
- 0.5 mL of the undiluted test substance or test substance formulation at the chosen concentrations were placed on a dry gauze pad (approximately 4 cm2) which was then applied to the skin and held in place by an occlusive dressing for 24 hours
- cutaneous reactions were evaluated approximately 24 and 48 hours after removal of dressings

MAIN STUDY
A. INDUCTION EXPOSURE
Intradermal route:
On day 1, six injections were made deep into the dermis of 4 cm x 2 cm clipped interscapular area, using a needle (diameter: 0.50 x 16 mm) mounted on a 1 mL plastic syringe (0.01 mL graduations).)

Cutaneous route:
On day 7, the interscapular area was clipped.
As the test substance was shown to be irritant during the preliminary test, a topical application with sodium lauryl sulfate was not necessary on day 7.
On day 8, a cutanous application to the region of the intradermal injections (4 cm x 2 cm) was performed as follows:
Control group: application of 0.5 mL of the vehicle
Treated group: application of 0.5 mL the test substance at the concentration of 10 % (w/w)

This application was performed using a 1 mL plastic syringe (0.01 mL graduations).
The test substance or the vehicle was placed on a dry gauze pad, which was then applied to the interscapular region.
The pad was held in place for 48 hours by means of an adhesive hypoallergenic dressing and an adhesive anallergenic waterproof plaster.
On removal of dressing, no residual test substance was observed.
The presence of cutanous irritation was checked 1 hour after removal of the occlusive dressing.

B. CHALLENGE EXPOSURE
- First challenge application:
On day 22, the animals of both groups received an application of 0.5 mL of the test substance at the concentration of 5 % (w/w) to the posterior right flank, and 0.5 mL of the vehicle to the posterior left flank. This application was preformed using a 1 mL plastic syringe (0.01 mL graduations). The test substance or the vehicle was plased on a dry gauze pad, which was then applied to a 4 cm2 (2 cm x 2 cm) clipped area of skin.
The pads were held in contact with the skin for 24 hours by means of an occlusive, hypoallergenic dressing and an adhesive anallergenic waterproof plaster.
On removal of dressing, no residual test substance was observed.
- Second challenge application:
On day 33, the animals of both groups received an application of 0.5 mL of the test substance at the concentration of 1 % (w/w) to the posterior left flank and 0.5 mL of the vehicle to the posterior right flank under the same experimental conditions as for the first challenge application.
On removal of dressing, no residual test substance was observed.

Challenge controls:

Challenge application: 1 % (w/w) DNCB

Positive control substance(s):

yes

Remarks:

2,4-dinitro chlorobenzene (DNCB)

Results and discussion

Positive control results:

Under this experimental conditions and according to the Magnusson and Kligman method, the test substance DNCB at the concetration of 1 % (w/w) induced positive skin sensitization reactions in 90 % of the guinea-pigs.

In vivo (non-LLNA)

Results

Results 1

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

5 %

No. with + reactions:

5

Total no. in group:

10

Clinical observations:

very slight erythema (grade 1)

Results 2

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

5 %

No. with + reactions:

20

Total no. in group:

20

Clinical observations:

very slight to well-defined erythema (grade 1 to 2)

Results 3

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

5 %

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Results 4

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

5 %

No. with + reactions:

2

Total no. in group:

20

Clinical observations:

well-defined erythema (grade 2)

Results 5

Key result

Reading:

rechallenge

Hours after challenge:

24

Group:

negative control

Dose level:

1 %

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Results 6

Key result

Reading:

rechallenge

Hours after challenge:

24

Group:

test chemical

Dose level:

1 %

No. with + reactions:

2

Total no. in group:

20

Clinical observations:

very slight erythema (test substance; left flank)

Results 7

Key result

Reading:

rechallenge

Hours after challenge:

24

Group:

test chemical

Dose level:

1 %

No. with + reactions:

2

Total no. in group:

20

Clinical observations:

very slight to well-defined erythema (vehicle, right flank)

Results 8

Key result

Reading:

rechallenge

Hours after challenge:

48

Group:

negative control

Dose level:

1 %

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

none

Remarks on result:

other: Reading: rechallenge. . Hours after challenge: 48.0. Group: negative control. Dose level: 1 %. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: none.

Results 9

Key result

Reading:

rechallenge

Hours after challenge:

48

Group:

test chemical

Dose level:

1 %

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

none

Remarks on result:

other: Reading: rechallenge. . Hours after challenge: 48.0. Group: test group. Dose level: 1 %. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: none.

Results 10

Group:

positive control

Remarks on result:

not measured/tested

Any other information on results incl. tables

- First challenge application:

A very slight erythema (grade 1) was observed in 5/10 control animals at the 24 -hour reading.

In the treated group, at the 24 -hour reading, a very slight or well-defined erythema (grade 1 or 2) was noted in 14/20 and 6/20 animals, respectively.

A well-defined erythema (grade 2) persisted in 2/20 animals at the 48 hour reading. Dryness of the skin was observed in 3/10 control and 14/20 treated animals at the 48 -hour reading.

As the origin of the observed cutaneous reactions was unclear (irritant effect and/or delayed contact hypersensitivity), a second challenge application was performed at a lower concentration of 1 % (w/w).

- Second challenge application:

No cutaneous reactions were observed in the control animals.

In the treated group, a very slight erythema (grade 1) was observed on the left flank (test substance at 1 % (w/w) and the right flank (vehicle) of 2/20 and 1/20 animals, respectively.

A well-defined erythema (grade 2) was observed on the right flank of 1/20 animals and dryness of the skin was noted on the same site at the 24 and 48 -hour readings.

As the few cutaneous reactions noted after the second challange application were very slight, non-persistent and had a low incidence, they were attributed to the irritant properties of the test substance.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under this experimental conditions, methyl-ethylketone peroxide in DMP/diacetone alcohol doses not induce delayed contact hypersensitivity.

Executive summary:

The potential of methyl-ethylketone peroxide in DMP/diacetone alcohol to induce delayed contact hypersensitivity was evaluated in guinea-pigs according to maximization method of Magnusson and Kligman (OECD No. 406 and EC 92/69/EEC, B.6).

Thirty Dunkin - Hartley guinea-pigs were allocated to two groups: a control group 1 (five males and five females) and a treated group 2 (ten males and ten females). On day 1, intradermal injections of Freund's complete adjuvant mixed with the test substance at the concentration of 0.1 % methyl-ethylketone peroxide in corn oil (treated group) or vehicle (control group) were performed in the interscapular region. On day 8, the test substance (treated group; 10 % methyl-ethylketone peroxide in corn oil) or the vehicle (control group) was applied to the same test site which was then covered by an occlusive dressing for 48 hours. On day 22, after a rest period of 12 days, all animals of the treated and control groups were challenged by a cutaneous application of the test substance to the right flank ( 5%). The left flank served as control and received the vehicle only. Test substance and vehicle were maintained under an occlusive dressing for 24 hours. Skin reactions were evaluated approximately 24 and 48 hours after removal of the dressing.

At the end of the study, animals were killed without examination of internal organs. No skin samples were taken from the challenge application sites. No clinical signs and no deaths related to treatment were noted during the study. First challenge application: A very slight erythema was observed in 5/10 control animals at the 24-hour reading. In the treated group, at the 24-hour reading, a very slight or well-defined erythema was noted in 14/20 and 6/20 animals, respectively. A well-defined erythema persisted in 2/20 animals at the 48-hour reading. Dryness of the skin was observed in 3/10 control and 14/20 treated animals at the 48-hour reading. As the orgin of the observed cutaneous reactions was unclear (irritant effect and/or delayed contact hypersensitivity), a second challenge application was performed at a lower concentration. Second challenge application: No cutaneous reactions were observed in the control animals. In the treated group, a very slight erythema was observed on the left flank (test substance at 1% (w/w)) and the right flank (vehicle) of 2/20 and 1/20 animals, respectively.A well-defined erythema was observed on the right flank of 1/20 animals and dryness of the skin was noted on the same test site at the 24 and 48-hour readings. As the few cutaneous reactions noted after the second challenge application were slight, non-persistent and had a low incidence, they were attributed to the irritant properties of the test substance.

The species and strain which were used showed a satisfactory sensitization response in 90% of the animals treated with DNCB

Based on the results obtained methyl ethylketone peroxide has not to classified and labelled with regard to skin sensitisation according to Regulation No. 1272/2008 (CLP).