Dilauroyl peroxide

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Apparently well conducted GLP study

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Dilauroyl peroxide

EC Number:

203-326-3

EC Name:

Dilauroyl peroxide

Cas Number:

105-74-8

Molecular formula:

C24H46O4

IUPAC Name:

dodecanoyl dodecaneperoxoate

Constituent 2

Reference substance name:

Laurox

IUPAC Name:

Laurox

Details on test material:

A consignment of 100 g (net) Laurox, white flakes, was received from the Sponsor on 2 October 1992. The test material was further identified by the
Batch No. 0029209020111, the CAS No. 105-74-8 and the EINECS No. 2033263. It was stated Dilauroyl peroxide and was 99.7% pure.
It was stored in a refrigerator (approximately 4°C), in the original container. The identity, strength and purity of the test material received, and its
stability under the storage conditions above, were the responsibility of the Sponsor. A certificate of analysis for the batch of test material used
on this study is presented in Appendix 1.

Test animals

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

Young albino rabbits of an outbred New Zealand White strain were supplied by Rosemead Rabbits, Rosemead, Waltham Abbey, Essex, England. They
were individually housed in suspended stainless steel cages mounted in mobile batteries (Modular Systems and Development Company limited,
London, England). The cages were fitted with perforated counter-sunk floor panels. Atray beneath the floor was lined with absorbent paper which was
changed regularly. Animals had free access to a commercially available standard pelleted rabbit diet (S.Q.C. Rabbit Diet, Special Diets Services
Limited, Witham, Essex, England). The rabbits had free access to tap water taken from the public supply; in England the supply and quality of this water is
governed by Department of the Environment regulations. Results of these analyses are retained in the archives. There was no information indicating
that normal levels of common contaminants, or specific contaminants, in the diet or drinking water would influence the outcome of the study.

The animals were housed in a lagomorph room within a limited-access building. The room was kept at slight positive pressure relative to the outside and had its own filtered air supply giving approximately 15 complete air changes per hour without re-circulation. A temperature range of 18-22°C
and a relative humidity range of 45-56% R.H. Electric time-switches operated a lighting cycle of 12 hours of artificial light per day. An emergency
generator was available to maintain the electricity supply in the event of a power failure.

Test system

Type of coverage:

semiocclusive

Preparation of test site:

other: Clipped

Vehicle:

unchanged (no vehicle)

Controls:

other: Second untreated test site on each animal served as a control

Amount / concentration applied:

0.5 grams

Duration of treatment / exposure:

4 hours

Observation period:

72 hours

Number of animals:

3

Details on study design:

Each animal was inspected on arrival, and unsuitable individuals were rejected. Individual bodyweight was recorded on the day of arrival and at weekly
intervals thereafter. All animals were identified by a uniquely numbered ear-tag. During the acclimatization period, the health status of each animal
was monitored and a record kept.

On the day before dosing, the dorsum between the limb girdles was clipped (chemical depilatories were not used). Bodyweight on the day of dosing was within the range 2.44 - 4.45 kg. The rabbits were either approximately three or six months old at this time.

Each rabbit was securely restrained by a technician. Two test sites (6 x 6 cm) were marked on either side of the clipped area of dorsum, moistened by direct application of approximately 0.2 ml distilled water per test site. A single dose (0.5 g) was applied directly to the skin and covered by an
unmedicated gauze patch (3 x 2 cm) which was held in place on the left test site by strips of Blenderm (Community Care Products, 3M Health Care,
Loughborough, England). The right test site, acting as a control, was covered by a similar semi-occlusive dressing but otherwise remained untreated. Pads of cotton wool and elasticated bandage were used to protect the patches and ensure good contact between the skin and the test material during the four-hour exposure period. The elasticated bandage was held in place by thin strips of waterproof plaster ('Blenderm') at both edges.
The dressings were removed after four hours exposure; the treatment sites were gently washed with warm water and dried with paper towels to
remove excess test material adhering to the skin.

Assessment of skin irritation responses at the control and treated test sites were made 1, 24, 48 and 72 hours after removal of the bandages.
Reactions of the test sites were assessed according to the criteria of Draize (1959) below .

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

erythema score

Basis:

animal: 362

Time point:

24/48/72 h

Score:

0

Results 2

Irritation parameter:

edema score

Basis:

animal: 362

Time point:

24/48/72 h

Score:

0

Results 3

Irritation parameter:

erythema score

Basis:

animal: 2091

Time point:

24/48/72 h

Score:

0

Results 4

Irritation parameter:

edema score

Basis:

animal: 2091

Time point:

24/48/72 h

Score:

0

Results 5

Irritation parameter:

erythema score

Basis:

animal: 455

Time point:

24 h

Score:

1

Results 6

Irritation parameter:

erythema score

Basis:

animal: 455

Time point:

48 h

Score:

0

Results 7

Irritation parameter:

erythema score

Basis:

animal: 455

Time point:

72 h

Score:

0

Results 8

Irritation parameter:

edema score

Basis:

animal: 455

Time point:

24/48/72 h

Score:

0

Irritant / corrosive response data:

Very slight erythema was observed in one rabbit during the first 24 hours following bandage removal. The test site of this rabbit was overtly normal by the 48 hour examination. No dermal response was observed at the test site of the remaining two animals at any time during the 72 hour
observation period.
The control sites did not show any response to the control procedure.

Other effects:

None

Any other information on results incl. tables

Summary of dermal lesions (following 4-h application)

no.	Effect	1  hour*	24-hours	48-hours	72-hours	Mean score erythema 24/48/72 h	Mean score oedema 24/48/72 h
362	Erythema/ eschar Oedema	0 0	0 0	0 0	0 0	0	0
455	Erythema/ eschar Oedema	1 0	1	0 0	0 0	0.3	0
2091	Erythema/ eschar Oedema	0 0	0	0 0	0 0	0	0

*~One hour following removal of dressing

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The 4 hour application of Laurox to the skin of rabbits, induced very slight erythema was observed in one rabbit during the first 24 hours
following bandage removal. The test site of this rabbit was overtly normal by the 48 hour examination. No dermal response was observed at the
test site of the remaining two animals at any time during the 72 hour observation period. Laurox is not classified as a skin irritatant in
accordance with GHS.

Executive summary:

The irritation potential of Lauox was assessed following the 4 hour application of 0.5 grams to the skin or rabbits in accordance with OECD 404. Test sites were evaluated for irritation one hour following bandage removal and 24, 48 and 72 hours following application.

The 4 hour application of Laurox to the skin of rabbits, induced very slight erythema was observed in one rabbit during the first 24 hours following bandage removal. The test site of this rabbit was overtly normal by the 48 hour examination. No dermal response was observed at the test site of the remaining two animals at any time during the 72 hour observation period.

Laurox is not classified as a skin irritatant in accordance with GHS.