Registration Dossier

Administrative data

Description of key information

- in vitro EPISKIN(TM) 15 min - 42h skin irritation test (OECD439) with neat WS400123:
Mean tissue viability after treatment with WS400123 = 103.9 ± 6.1 %. Validity of the assay confirmed for negative and positive controls. Therefore, WS400123 predicted to be not irritant to skin.
- in vivo skin irritation/corrosion rabbit (OECD 404 of 1981), 24 h occlusive treatment of intact or abraded skin with formulation containing ca. 50% WS400123
Intact skin: At each observation time point (0, 48 h and 6 d post patch removal) no erythema and no edema reaction in each of 5 animals.
Abraded skin: Only at 0 h post patch removal erythema and edema, both grade 1, in all animals. Apart from these, no skin reactions during the study.
- 2 in vivo eye irritation studies, rabbit (OECD 405), one with neat, the other with ca. 50% formulation of WS400123:
All findings noted were fully reversible and their incidence has been within the category “not irritating to eyes”.
Conclusion from all skin and eye irritation studies: No requirement of classification regarding skin or eye irritation/corrosion.
- Local lymph node assay, mouse (Endpoint study record "7.4.1 Skin sensitisation - LLNA_mouse_HLS_GAH0111"):
Group Mean Stimulation Index (SI) = 1.0, 3.9, 6.4 and 10.1 at test substance concentrations of 0 % (vehicle control), 25, 50 and 100% w/v, respectively.
Conclusion: Classification and labelling as
"irritant (Xi)" and "may cause sensitisation by skin contact (R43)" [DIRECTIVE 67/548/EEC] and
“Category 1, subcategory 1B” [Warning: May cause an allergic skin reaction; other (than strong) skin sensitiser]" [REGULATION (EC) 1272/2008]

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records
Reference
Endpoint:
skin irritation: in vivo
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was conducted according to internationally accepted technical guidelines and in compliance with GLP in a contract research organization. The study is scientifically valid and the report is fully adequate for assessment, despite some minor restrictions (e.g. due to limited reporting).
Qualifier:
according to
Guideline:
OECD Guideline 404 (Acute Dermal Irritation / Corrosion)
Version / remarks:
of 1981
Deviations:
yes
Remarks:
24 h instead of 4 h exposure to a formulation of WS400123. Skin examination 0 h, 48 h and 6 days after patch removal.
Qualifier:
according to
Guideline:
other: Appraisal of the Safety of Chemicals in Foods, Drugs and Cosmetics, Division of Pharmacology, FDA
Deviations:
not specified
GLP compliance:
yes
Species:
rabbit
Strain:
New Zealand White
Details on test animals and environmental conditions:
- Number: 5 animals,
- Average bodyweight: 3.0 kg
- Housing: Individual housing in cages.
- Diet: Commercially available standard laboratory diet for rabbits ( Altromin, Lage, Germany).
- Water: Ad libitum

ENVIRONMENTAL CONDITIONS

Room temperature kept constant at 18±2°C, the relative humidity at 50-60%. 12 hours illumination per day.

Type of coverage:
occlusive
Preparation of test site:
other: abraded versus only shaved
Vehicle:
unchanged (no vehicle)
Remarks:
The test substance was a 50% aquaeous formulation
Controls:
not required
Amount / concentration applied:
0.5 mL of the test material (i.e. formulation containing 49.86% WS400123) was administered to the skin by means of a "2.5 cm2" cellulose patch.*

* Comment by the data submitter:
There is no indication in the report, whether the size of treated skin patches was inadvertently stated as only "2.5 cm2" in reality having been sized 2.5 cm x 2.5 cm (i.e. ca. 6 cm2) or whether, contrarily to the cited OECD 404 test guideline, the size of the treated skin patches was really confined to only 2.5 cm2. Regardless whether the treated skin patch was ca. 6 cm2 or only 2.5 cm2, the study results are considered to be valid for assessment.
Duration of treatment / exposure:
24 hours
Observation period:
7 days (i.e. the final observation time point was 6 days post patch removal)
Number of animals:
5
Details on study design:
TEST SITE PREPARATION

Samples of 0.5 mL of the unchanged test material were applied to the shaved intact and to shaved and then abraded skin of albino rabbits by means of cellulose patches. Patches were fixed with Leukoplast(R) and the whole trunk of each animal was enwrapped by a rubber cloth during the 24 hour treatment period, in order to delay evaporation of substances. From the coverage of the whole animal trunk (patches inclusive) with rubber cloth occlusive treatment was concluded by the data submitter, although the report did not specify whether this coverage was considered to be occlusive or semi-occlusive.

Two untreated skin sites (one of shaved intact skin and one of shaved and then abraded skin) served as controls. Only skin reactions different to controls were graded as positive skin reactions.


TREATMENT PERIOD AND REMOVAL OF TEST SUBSTANCE

Occlusive treatment lasted 24 hours. Then the dressings were removed. There was no mentioning in the report that exposed skin patches were cleaned from residual test substance after treatment.

TIME POINTS OF SKIN EVALUATION:

The treated skin patches were evaluated 24 and 72 hours and 7 days post application (i.e. immediately and 48 hours and 6 days post patch removal). The scoring system for the grading of skin reactions is listed in Table 1 (next field below).

Reporting of irritation results in the present robust study summary has been focused to those attained on intact skin, as currently valid test guidelines do not require treatment of abraded skin.
Irritation parameter:
erythema score
Remarks:
as defined in Table 1
Basis:
mean
Remarks:
over 5 animals and 2 time points
Time point:
other: 24 and 72 h post treatment start
Score:
0
Max. score:
4
Reversibility:
other: erythema formation was not evident
Remarks on result:
other: Administered to intact skin for 24 hours
Irritation parameter:
edema score
Remarks:
as defined in Table 1
Basis:
mean
Remarks:
over 5 animals and 2 time points
Time point:
other: 24 and 72 h post treatment start
Score:
0
Max. score:
4
Reversibility:
other: edema formation was not evident
Remarks on result:
other: Administered to intact skin for 24 hours
Irritation parameter:
erythema score
Remarks:
as defined in Table 1
Basis:
mean
Remarks:
over 5 animals and 2 time points
Time point:
other: 24 and 72 h post treatment start
Score:
0.5
Max. score:
4
Reversibility:
fully reversible within: 72 hours post treatment start, i.e. within 48 hours post patch removal
Remarks on result:
other: Administered to abraded skin for 24 hours
Irritation parameter:
edema score
Remarks:
as defined in Table 1
Basis:
mean
Remarks:
over 5 animals and 2 time points
Time point:
other: 24 and 72 h post treatment start
Score:
0.5
Max. score:
4
Reversibility:
fully reversible within: 72 hours post treatment start, i.e. within 48 hours post patch removal
Remarks on result:
other: Administered to abraded skin for 24 hours
Irritant / corrosive response data:
In each animal, shaved intact skin patches treated with a test material formulation (containing 49.86 % WS400123) for 24 hours were free from erythema, scab or edema formation at any observation time point of the study, whereas on abraded skin patches treated with the same dose erythema and edema, both grade 1, were recorded in each animal at 24 hours post treatment start, i.e. immediately after patch removal. These findings were fully reversible, as by 72 hours after treatment start test material treated abraded skin patches did not differ from control abraded skin patches.
Other effects:
None
Interpretation of results:
not irritating
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Occlusive administration of an undiluted test material formulation (containing 49.86% WS400123) to shaved, intact skin of five rabbits for 24 hours did not induce any skin reactions during the present study. The same treatment to abraded skin induced only erythema and edema, both grade 1, in each of 5 animals, which were fully reversible within 72 hours post treatment start. In view of the absence of any irritating effects of this formulation on intact skin and the very mild and fully reversible erythema and edema reactions of abraded skin, the present study provides supporting evidence that only 4 h exposure of intact skin to undiluted WS400123 would not induce skin reactions necessitating any labelling regarding skin irritation according to EU classification rules [DIRECTIVE 67/548/EEC and REGULATION (EC) 1272/2008].
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

The conduct of an in vitro skin corrosion test (OECD 431) was deemed unnecessary for the following reasons:
1. Absence of any dermal irritation in the local lymph node assay in mice treated with WS400123 at up to and including 100% w/v,

2. Non-irritancy of neat WS400123 in the in vitro EPPISKIN skin irritation study, and of WS400123 formulation in the in vivo skin irritation study.

3. Absence of relevant eye irritation or corrosion in the in vivo eye irritation studies with neat WS400123 or WS400123 formulation,
4. S
kin corrosion properties of WS400123 are not to be expected from its pH value (measured to be 7.64 as part of the in vivo eye irritation study with neat WS400123).

Justification for classification or non-classification

In view of the absence of any relevant effects during the skin and eye irritation studies with WS400123, the attained results do not necessitate any classification and labelling regarding skin or eye irritation according to EU classification rules [DIRECTIVE 67/548/EEC and REGULATION (EC) 1272/2008].

 

However, the positive sensitisation response elicited at three concentration levels of WS400123 in a local lymph node assay* in mice necessitates classification and labelling as "irritant (Xi)" and "May cause sensitisation by skin contact (R43)” according to DIRECTIVE 67/548/EEC and as “Category 1” (Warning: May cause an allergic skin reaction) according to REGULATION (EC) 1272/2008.

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*Endpoint study record "7.4.1 Skin sensitisation - LLNA_mouse_HLS_GAH0111”