tert-butyl peracetate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1998-10-19 and 1998-11-20

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

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:

1996

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The Guinea Pig Test (1999) met the previous requirements before the entry into force of REACH. The test 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:

tert-butyl peracetate

EC Number:

203-514-5

EC Name:

tert-butyl peracetate

Cas Number:

107-71-1

Molecular formula:

C6H12O3

IUPAC Name:

tert-butyl ethaneperoxoate

Details on test material:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: in the refrigeratore in the dark between +10 and +30°C

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River, Germany
- Age at study initiation: approx. 4 weeks
- Weight at study initiation: individual bw did not exceed 500 g
- Housing: 5 animals per labelled metal cage with wire-mesh floors
- Diet: standard guinea pig diet, including ascorbic acid (1600 mg/kg), LC-23 B, pellet diameter 4 mm (Hope farms, Woerden, The Netherlands), ad libitum; hay once a week
- Water: tap-water, diluted with decalcified water; ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21
- Humidity (%): 50
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Induction

Route:

intradermal and epicutaneous

Vehicle:

corn oil

Concentration / amount:

intradermal injection:
a) 10%
b) 1:1 mixture of FCA and 20% test substance concentration
epidermal application:
50% test substance concentration

Challenge

Route:

epicutaneous, semiocclusive

Vehicle:

corn oil

Concentration / amount:

epidermal, challenge:
10% test substance concentration

No. of animals per dose:

experimental group: 10 females
control group: 5 females

Details on study design:

RANGE FINDING TESTS:
A. INTRADERMAL INJECTIONS:
- Concentrations: 100%, 50%, 20% and 10% test substance
- each of two animals received two different concentrations in duplicate (0.1 mL/site) in the clipped scapular region
- the injection sites were assessed for irritation 24 and 48 hours after treatment

B. EPIDERMAL APPLICATION:
- Concentrations: 100%, 50%, 20% and 10% test substance
- 2 different concentrations were applied (0.5 mL each) per animal to the clipped flank
- animals receiving intradermal injections were treated with the lowest concentrations and two further animals with the highest concentrations
- Time of exposure: 24 hours
- Observation point after exposure: 24 and 48 hours

MAIN STUDY
A.1. INDUCTION EXPOSURE (intradermal), on day 1
- Exposure period: three pairs of intradermal injections (0.1 mL/site)
- Test groups: (A) 1:1 mixture (w/w) of FCA and water, (B) 10% test substance concentration, (C) 1:1 mixture (w/w) of FCA and a 20% test substance concentration
- Control group: were treated as decribed for the experimental animals, except that, instead of the test substance, the vehicle was administered
- Site: scalpular region; one of each pair was on each side of the midline and from cranial (A) to caudal (C)
- Duration: single injection

A.2 INDUCTION EXPOSURE (epidermal), on day 8
- Test group: 50% test substance concentration
- Control group: see comment in section A.1.
- Site: scalpular area between the injection sites
- Duration 48 hours

B. CHALLENGE EXPOSURE; on day 22
- No. of exposures: 1
- Exposure period: 24 hours
- Test group and control group: 10% test substance concentration and the vehicle
- Site: flank
- Evaluation (hr after challenge): 24 and 48 hours

Challenge controls:

yes

Positive control substance(s):

yes

Remarks:

Alpha-Hexylcinnamicaldehyde, Tech. 85%

Results and discussion

Positive control results:

The results lead to a sensitisation rate of 100 per cent of the 10% concentration. From these results, it was concluded that the female guinea pig of the albino Dunkin Hartley strain is an appropriate animal model for the performance of studies designed to evaluate the sensitising potential of a substance in a Maximisation type of test.

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

10%

No. with + reactions:

0

Total no. in group:

5

Results 2

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

0%

No. with + reactions:

0

Total no. in group:

5

Results 3

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

10%

No. with + reactions:

0

Total no. in group:

5

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

0%

No. with + reactions:

0

Total no. in group:

5

Results 5

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

10%

No. with + reactions:

7

Total no. in group:

10

Results 6

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

0%

No. with + reactions:

0

Total no. in group:

10

Results 7

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

10%

No. with + reactions:

7

Total no. in group:

10

Clinical observations:

one animal showed scaliness

Results 8

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

0%

No. with + reactions:

0

Total no. in group:

10

Results 9

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Remarks on result:

not measured/tested

Any other information on results incl. tables

No mortality occured and no symptoms of systemic toxicity were observed in the animals of the main study.

Body weights and body weight gain of the experimental animals remained in the same range as controls over the study period.

Seven animals of the 24 readings and seven animals of the 48 readings in the challenge phase were considered indicative of sensitisation. In sum eight different animals were considered indicative of sensitisation.

 

The skin effects caused by the intradermal injections and epidermal exposure during the induction phase are given in the following table.

Animal Number	Intradermal Injection (Day 3) A                                            B                                                    C			Epidermal Exposure (Day 10)                          D
Control 1 2 3 4 5	E2 E3 E3 E3 E4	E2 E1 NA NA NA	E3 E3 E2 E3 E3	Erythema 0 0 0 0 0	Oedema 0 0 0 0 0
Experimental 6 7 8 9 10 11 12 13 14 15	E2 E3 E2 E2 E3 E3 E3 E3 E2 E2	E1 E3 NA E1 E2 E1 E1 E1 E1 E1	E2 E3 E3 E4 E4 E4 E3 E3 E3 E2	2 2 0 2 2 2 2 3 1 2	0 0 0 0 0 0 0 0 0 0

A. 1:1 Mix of FCA and water

B. 10% test substance concentration (experimental); vehicle (control)

C. 1:1 Mix of FCA and a 20% concentration (experimental) or vehicle (control)

D. 50% test substance concentration (experimental); vehicle (control)

Skin effects intradermal injections: NA no abnormalities; E( ) Erythema (grade)

Applicant's summary and conclusion

Interpretation of results:

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

Conclusions:

The skin reactions observed in response to a 10% test substance concentration in 7 (of the 10) experimental animals in the challenge phase were considered indicative of sensitisation, based on the absence of any response in the control animals. The results indicate a sensitisation rate of 70 per cent.

Executive summary:

The test substance (50% in aromatic free mineral spirit) were tested for contact hypersensitivity in the albino guinea pig according to the EU method B6, the OECD guideline 406 and based on the method described by Magnusson and Kligman. Test substance concentrations selected for the main study were based on the results of a preliminary study. In the main study, 10 experimental animals were intradermally injected with 10% concentration and epidermally exposed to a 50% concentration. 5 control animals were similarly treated, but with the vehicle (corn oil) only. Two weeks after the epidermal application all animals were challenged with a 10% test substance concentration and the vehicle.

No mortality occured and no symptoms of systemic toxicity were observed in the animals of the main study. Body weights and body weight gain of experimental animals remained in the same range as controls over the study period.

Skin reactions of grade 1 were observed in eight experimental animals in response to the 10% test substance concentration. No skin reactions were evident in the control animals. Scaliness was seen in the treated skin site of one experimental animal. The skin reactions observed in response to a 10% test substance concentration in 7 (of the 10) experimental animals in the challenge phase were considered indicative of sensitisation, based on the absence of any response in the control animals. The results indicate a sensitisation rate of 70 per cent.