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Toxicological information

Skin irritation / corrosion

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Administrative data

Endpoint:
skin irritation: in vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Between 24 April 2012 and 10 May 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 404 (Acute Dermal Irritation / Corrosion)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.4 (Acute Toxicity: Dermal Irritation / Corrosion)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
semi-solid (amorphous): gel
Remarks:
migrated information: paste
Details on test material:
Sponsor's identification: Bis(2,4-dichlorobenzoyl) peroxide (CAS# 133-14-2), paste, 50% in silicone oil
Description : white paste
Batch number : 1012011395
Purity : 50.7%
Date received : 08 November 2011
Expiry date : 01 January 2013
Storage conditions: approximately -20°C in the dark
The integrity of supplied data relating to the identity, purity and stability of the test item is the responsibility of the Sponsor.
A Certificate of Analysis supplied by the Sponsor is given in Appendix 1 (attachment 1).

Test animals

Species:
rabbit
Strain:
New Zealand White
Details on test animals and environmental conditions:
Two New Zealand White (Hsdlf:NZW) strain rabbits were supplied by Harlan Laboratories UK Ltd., Leicestershire, UK. At the start of the study the animals weighed 2.35 or 3.19 kg and were twelve to twenty weeks old. After an acclimatisation period of at least five days each animal was given a number unique within the study which was written with a black indelible marker-pen on the inner surface of the ear and on the cage label.
The animals were individually housed in suspended cages. Free access to mains drinking water and food (2930C Teklad Global Certified Rabbit diet supplied by Harlan Laboratories UK Ltd., Oxon, UK) was allowed throughout the study. The diet and drinking water were considered not to contain any contaminant of a level that might have affected the purpose or integrity of the study.
The temperature and relative humidity were set to achieve limits of 17 to 23°C and 30 to 70% respectively. Any occasional deviations from these targets were considered not to have affected the purpose or integrity of the study. The rate of air exchange was at least fifteen changes per hour and the lighting was controlled by a time switch to give twelve hours continuous light (06:00 to 18:00) and twelve hours darkness.
The animals were provided with environmental enrichment items which were considered not to contain any contaminant of a level that might have affected the purpose or integrity of the study.

Test system

Type of coverage:
semiocclusive
Preparation of test site:
other: clipped
Vehicle:
unchanged (no vehicle)
Controls:
no
Amount / concentration applied:
A quantity of 0.5 ml of the test item was applied directly to the skin
Duration of treatment / exposure:
4 hours
Observation period:
7 days
Number of animals:
2
Details on study design:
On the day before the test each rabbit was clipped free of fur from the dorsal/flank area using veterinary clippers. Only animals with a healthy intact epidermis by gross observation were selected for the study.
One rabbit was initially treated. Three suitable sites were selected on the back of the rabbit. A quantity of 0.5 ml of the test item was applied directly to the skin under a 2.5 cm x 2.5 cm cotton gauze patch. Each patch was secured in position with a strip of surgical adhesive tape. To prevent the animal interfering with the patches, the trunk of the rabbit was wrapped in an elasticated corset for the duration of the exposure period.
One patch was removed at each of three time points: 3 minutes, 1 hour and 4 hours after application. Any residual test item was removed by gentle swabbing with cotton wool soaked in distilled water.
After consideration of the skin reactions produced in the first animal, an additional animal was treated with 0.5 ml of test item. One patch was applied to the back of the rabbit and was allowed to remain in contact with the skin for a period of four hours.
Immediately following removal of the patches and approximately 1, 24, 48 and 72 hours later, the test sites were examined for evidence of primary irritation and scored according to the following scale:
EVALUATION OF SKIN REACTIONS
Erythema and Eschar Formation Value
No erythema 0
Very slight erythema (barely perceptible) 1
Well-defined erythema 2
Moderate to severe erythema 3
Severe erythema (beef redness) to eschar formation preventing grading of erythema 4
Oedema Formation Value
No oedema 0
Very slight oedema (barely perceptible) 1
Slight oedema (edges of area well-defined by definite raising) 2
Moderate oedema (raised approximately 1 millimetre) 3
Severe oedema (raised more than 1 millimetre and extending beyond the area of exposure) 4
Any other skin reactions and clinical signs of toxicity, if present, were also recorded.
An additional observation was made on Day 7 to assess the reversibility of skin reactions.
Individual bodyweights were recorded on Day 0 (the day of dosing) and at the end of the observation period.

Results and discussion

In vivo

Resultsopen allclose all
Irritation parameter:
other: Erythema/Eschar Formation
Basis:
animal: 71953 male
Time point:
other: Highest score at 0, 24, 48, 72 hours and 7 days
Score:
2
Max. score:
4
Reversibility:
fully reversible within: 7 days
Irritation parameter:
other: Erythema/Eschar Formation
Basis:
animal: 71986 Male
Time point:
other: Highest score at 0, 24, 48, 72 hours and 7 days
Score:
2
Max. score:
4
Reversibility:
fully reversible within: 7 days
Irritation parameter:
other: Oedema Formation
Basis:
animal: 71953 male
Time point:
other: Highest score at 0, 24, 48, 72 hours and 7 days
Score:
1
Max. score:
4
Reversibility:
fully reversible within: 72 hours
Irritation parameter:
other: Oedema Formation
Basis:
animal: 71986 male
Time point:
other: Highest score at 0, 24, 48, 72 hours and 7 days
Score:
1
Max. score:
4
Reversibility:
fully reversible within: 48 hours
Irritant / corrosive response data:
3-Minute Exposure Period
The individual scores for erythema/eschar and oedema are given in Table 1.
No evidence of skin irritation was noted during the study.

1-Hour Exposure Period
The individual scores for erythema/eschar and oedema are given in Table 1.
No evidence of skin irritation was noted during the study.

4-Hour Exposure Period
The individual scores for erythema/eschar and oedema are given in Table 2.
Well-defined erythema and very slight oedema were noted at both treated skin sites at the 24 Hour observation. Well-defined erythema and very slight oedema persisted at one treated skin site with very slight erythema noted at the other treated skin site at the 48 Hour observation. Very slight erythema was noted at both treated skin sites at the 72 Hour observation.
Both treated skin sites appeared normal at the 7 Day observation.
Other effects:
Bodyweight
Individual bodyweights and bodyweight changes are given in Table 3.
Both animals showed expected gain in bodyweight during the study.

Any other information on results incl. tables

Interpretation of Results

Calculation of Primary Irritation Index and Grading of Irritancy Potential Using the Draize Scheme

The scores for erythema and oedema at the 24 and 72‑Hour readings were totalled for the two test rabbits (8 values) and this total was divided by four to give the primary irritation index of the test item. The test item was classified according to the following scheme devised by Draize J H (1959) "Dermal Toxicity" In: Appraisal of the Safety of Chemicals in Foods, Drugs and Cosmetics. Association of Food and Drug Officials of the,,, p.46‑59:

Primary Irritation Index

Classification of Irritancy

0

Non-irritant

> 0 to 2

Mild irritant

> 2 to 5

Moderate irritant

> 5 to 8

Severe irritant

If irreversible alteration of the dermal tissue is noted in any rabbit, as judged by the Study Director, which include ulceration and clear necrosis or signs of scar tissue, the test item is classified as corrosive to rabbit skin. Classification according to Draize may, therefore, not be applicable.

The results were also interpreted according to Regulation (EC) No. 1272/2008 on the classification, labelling and packaging of substances and mixtures.

Table 1              Individual Skin Reactions Following 3-Minute and 1-Hour Exposures

Skin Reaction

Observation Time
(following patch removal)

Individual Scores - Rabbit Number and Sex

71953Male

3-Minute Exposure

1-Hour Exposure

Erythema/Eschar Formation

Immediately

0

0

1 Hour

0

0

24 Hours

0

0

48 Hours

0

0

72 Hours

0

0

7 Days

0

0

Oedema Formation

Immediately

0

0

1 Hour

0

0

24 Hours

0

0

48 Hours

0

0

72 Hours

0

0

7 Days

0

0

Table 2              IndividualSkin ReactionsFollowing 4-Hour Exposure

Skin Reaction

Observation Time
(following patch removal)

Individual Scores – Rabbit Number and Sex

Total

71953Male

71986Male

Erythema/Eschar Formation

Immediately

0

0

(0 )

1 Hour

0

0

( 0 )

24 Hours

2

2

4

48 Hours

2

1

( 3 )

72 Hours

1

1

2

7 Days

0

0

( 0 )

Oedema Formation

Immediately

0

0

( 0 )

1 Hour

0

0

( 0 )

24 Hours

1

1

2

48 Hours

1

0

( 1 )

72 Hours

0

0

0

7 Days

0

0

( 0 )

Sum of 24 and 72‑Hour(S)    :          8

Primary Irritation Index (S/4)                  :          8/4 = 2.0

Classification                                       :          MILD IRRITANT

(   ) = Total values not used for calculation of primary irritation index

Table 3              Individual Bodyweights and Bodyweight Changes

Rabbit Number
and Sex

Individual Bodyweight (kg)

Bodyweight Change (kg)

Day 0

Day 7

71953Male

3.19

3.37

0.18

71986Male

2.35

2.46

0.11


Applicant's summary and conclusion

Interpretation of results:
other: MILD IRRITANT
Remarks:
Criteria used for interpretation of results: other: Draize classification scheme
Conclusions:
The test item produced a primary irritation index of 2.0 and was classified as a MILD IRRITANT to rabbit skin according to the Draize classification scheme. No corrosive effects were noted.
The test item did not meet the criteria for classification according to Regulation (EC) No. 1272/2008 on the classification, labelling and packaging of substances and mixtures.
Executive summary:

Introduction. The study was performed to assess the irritancy potential of the test item to the skin of the New Zealand White rabbit. The method was designed to be compatible with the following:

OECD Guidelines for the Testing of Chemicals No. 404 "Acute Dermal Irritation/Corrosion" adopted 24 April 2002)

Method B4 Acute Toxicity (Skin Irritation) of Commission Regulation (EC) No. 440/2008

Results. 3-minute and 1-hour semi-occluded applications of the test item to the intact skin of one rabbit produced no evidence of skin irritation.

A single 4-hour, semi-occluded application of the test item to the intact skin of two rabbits produced well-defined erythema and very slight oedema. Both treated skin sites appeared normal at the 7-Day observation. No corrosive effects were noted.

Conclusion. The test item produced a primary irritation index of 2.0 and was classified as a mild irritant to rabbit skin according to the Draize classification scheme.

The test item did not meet the criteria for classification according to Regulation (EC) No. 1272/2008 on the classification, labelling and packaging of substances and mixtures.