Registration Dossier

Administrative data

Endpoint:
skin irritation: in vitro / ex vivo
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
Year:
2011

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 431 (In Vitro Skin Corrosion: Human Skin Model Test)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test substance (as cited in study report): Cyanethylimidazol
- Analytical purity: > 70% - < 80% (18% - 28% Water)
- Impurities: Acrylnitril > 2% - < 4%; Imidazole 3%
- Test substance No.: 11/0432-1
- Batch No.: 000STD77L0 of C1310
- Homogeneity: the tets substance was homogenous by visual inspection.
- Storage stability: the stability under storage conditions over the study period was guaranteed by the sponsor.
- pH-value: ca. 8 (undiluted test substance)

Test animals

Species:
other: in vitro test on three dimensional human epidermis model (EpiDermTM model which consists of human-derived epidermal keratinocytes cultured to form a multi layered, highly differentiated model of the human epidermis.)
Strain:
other: not applicable

Test system

Type of coverage:
other: not applicable
Preparation of test site:
other: not applicable
Vehicle:
unchanged (no vehicle)
Controls:
other: not applicable (in vitro test)
Amount / concentration applied:
- Corrosion test: 50 µL
- Irritation test: 30 µL
Duration of treatment / exposure:
- Corrosion test: 3 min and 1 h
- Irritation test: 1 h (42-h post-incubation period)
Observation period:
not applicable (in vitro test)
Number of animals:
not applicable (in vitro test)
Details on study design:
- Justification for skin model:
The objective was to assess the potential for corrosive activity and skin irritation of the test material upon first contact with skin. The assessment of the skin corrosion/irritation potential is included in international regulatory requirements for the testing of chemicals. Due to animals welfare reasons corrosivity and skin irritation were determined using the reconstructed human epidermal model EpiDermTM.
The present test is based on the experience that corrosive and irritant chemicals produce cytotoxicity in human reconstructed epidermis after a short term topical exposure. The test is designed to predict the skin corrosion or irritation potential of a chemical by using the three dimensional human epidermis model EpiDermTM. After application of the test material to the stratum corneum surface of the EpiDermTM tissue the induced cytotoxicity (= loss of viability) is measured by a colourimetric assay. Cytotoxicity is expressed as the reduction of mitochondrial dehydrogenase activity. The mitochondrial dehydrogenase reduces the yellow coloured water soluble MTT to the insoluble blue coloured formazan. After isopropanol extraction of the formazan from the tissues, the optical densitiy of the extract is determined spectrophotometrically. Optical density of the extracts of test substance treated tissues is compared to negative control values and expressed as relative tissue viability.
The study was conducted in two steps: first the irritation test and subsequently the corrosion test.

- Evaluation criteria:
1) the test substance is considered corrosive to the skin if the mean tissue viability (% of negative control) after 3 min treatment is less than 50% or if the mean tissue viability is >= 50% after 3 min treatment and less than 15% after 1 h treatment.
2) the test substance is considered as irritant if the mean relative tissue viability is less than or equal to 50%.

Results and discussion

In vitro

Resultsopen allclose all
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
3 min exposure (corrosion test)
Value:
102
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
1 h exposure (corrosion test)
Value:
97
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
1 h exposure, 42 h post-incubation (irritation test)
Value:
96

Any other information on results incl. tables

Table 1: corrosion test

Test

substance

 

Expsosure: 3 min

Exposure:1 hour

Tissue 1

Tissue 2

Mean

Tissue 1

Tissue 2

Mean

NC

Mean OD570

1.762

1.793

1.777

1.595

1.593

1.594

Viability (% of NC)

99.1

100.9

100

100.1

99.9

100

Test

Substance

Mean OD570

1.724

1.909

1.816

1.389

1.716

1.553

Viability (% of NC)

97.0

107.4

102

87.1

107.6

97

PC

Mean OD570

0.368

0.405

0.386

0.190

0.084

0.137

Viability (% of NC)

20.7

22.8

22

11.9

5.3

9

The value for inter-tissue variability of the test substance for the exposure period of 1 hour is 0.33 and therefore out of the acceptance range. Since the lower value still corresponds to a viability of 87%, this deviation is not considered to adversely affect the result of this study.

Table 2: irritation test

Test

substance

 

Tissue 1

Tissue 2

Tissue 3

Mean

SD

NC

Mean OD570

2.039

1.922

1.982

1.981

 

Viability (% of NC)

102.9

97.0

100.1

100

2.97

Test

Substance

Mean OD570

1.923

1.945

1.847

1.905

 

Viability (% of NC)

97.1

98.2

93.2

96

0.35

PC

Mean OD570

0.107

0.117

0.100

0.108

 

Viability (% of NC)

5.4

5.9

5.1

5

0.42

Applicant's summary and conclusion

Interpretation of results:
not irritating
Remarks:
Migrated information