Registration Dossier

Administrative data

Endpoint:
skin corrosion: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From January 22, 2018 to January 25, 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)
Version / remarks:
Adopted Jul. 29, 2016
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.40 (In Vitro Skin Corrosion: Transcutaneous Electrical Resistance Test (TER))
Version / remarks:
Dated May 30, 2008
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
Test Substance Name: Zinc acrylate
Batch no: SC1703131C
Test Facility Identification Number: 17102308G
Appearance: White powder
Composition: 99.5% Zinc acrylate
Purity: 99.5% Zinc acrylate
Homogeneity: Homogeneous
Expiry date: Sep. 09, 2018
Storage: Room emperature: (20 ± 5°C), keep away from humidity.

In vitro test system

Test system:
other: EpiDermTM Kit (EPI-212-SCT; Batch# 25875)
Source species:
other: Human-derived
Cell type:
other: Human-derived epidermal keratinocytes which have been cultured to form a multi-layered, highly differentiated model of the human epidermis.
Cell source:
other: Supplier: MatTek In Vitro Life Science Laboratories, Bratislava.
Source strain:
not specified
Justification for test system used:
The test system consists of organized basal, spinous and granular layers, and a multi-layered stratum corneum containing intercellular lamellar lipid layers arranged in patterns analogous to those found in vivo.
Vehicle:
water
Remarks:
Demineralised water, prepared by LAUS GmbH, from an ion-exchanger, batch no: 20170815.
Details on test system:
- Environmental Condition during incubation / exposure: 37 ± 1°C and 5.0 ± 0.5% CO2
- Amount of test substance applied: 26.0 and 26.1 mg (3 minutes exposure); 26.6 mg (1 h exposure)
Control samples:
yes, concurrent vehicle
yes, concurrent positive control
Amount/concentration applied:
3 minutes exposure: 26.0 mg (Tissue 1); 26.1 mg (Tissue 2)
1 h exposure: 26.6 mg (Tissue 1 and 2)
Duration of treatment / exposure:
3 minutes exposure
1 h exposure
Number of replicates:
2

Results and discussion

In vitro

Resultsopen allclose all
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
3 minutes treatment
Value:
ca. 72.5
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: Inconclusive, to be determined based on 1 h reading
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
1 h treatment
Value:
ca. 10.7
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
positive indication of irritation
Other effects / acceptance of results:
All Validity criteria for the Experiment were met:
1.    The criterion for optical density of the negative control (≥ 0.8 and ≤ 2.8) was fulfilled: optical density was 2.1 (3 minutes); 2.0 (1 h).
2.    The positive control showed clear corrosive effects. The criterion for the viability of the 1 h experiment, expressed as % of the negative control (< 15%), was fulfilled, too. The mean value of relative tissue viability was 9.9%.
3.    Values for negative control and for positive control were within the range of historical data of the test facility

Any other information on results incl. tables

The mean value of relative tissue viability of the test substance was reduced to 72.5% after 3 minutes treatment. Per criteria for assessment of corrosivity, this value is above the threshold for corrosively (50%). After 1 h treatment, the mean value of relative tissue viability of the test substance was reduced to 10.7%, lying below the threshold for corrosively (15%). Therefore, the test substance is considered as corrosive to skin.

The values of the negative control met the required acceptability criterion of mean OD ≥ 0.8 and ≤ 2.8 for both treatment intervals, thus showing the quality of the tissues. The positive control has met the validity criterion too, thus ensuring the validity of the test system.

Absorbance values blank isopropanol (OD 570 nm)
Replicate 1 2 3 4 5 6 Mean
Absorbance 0.039 0.038 0.039 0.04 0.038 0.038 0.039
Replicate 7 8 9 10 11 12
Absorbance 0.04 0.038 0.043 0.038 0.039 0.038

Absorbance values (OD 570 nm) of negative control, test substance and positive control 
Incubation Negative Control Test substance Positive Control
  Tissue 1 Tissue 2 Tissue 1 Tissue 2 Tissue 1 Tissue 2
3 min 2.125 2.117 1.456 1.576 0.404 0.447
2.115 2.09 1.527 1.587 0.427 0.446
2.147 2.093 1.527 1.593 0.423 0.446
1 h 2 1.974 0.25 0.248 0.26 0.224
2.093 2.009 0.259 0.25 0.244 0.221
2.116 1.988 0.259 0.251 0.246 0.225

Mean Absorbance Values of the 3 Minutes Experiment
Designation Negative Control Test substance Positive Control
Mean – blank (tissue 1) 2.09 1.464 0.379
Mean – blank (tissue 2) 2.061 1.546 0.407
Mean of the two tissues 2.076 1.505 0.393
RSD 1.00% 3.90% 5.10%

Mean Absorbance Values of the 1 h Experiment
Designation Negative Control Test substance Positive Control
Mean – blank (tissue 1) 2.031 0.217 0.211
Mean – blank (tissue 2) 1.951 0.211 0.184
Mean of the two tissues 1.991 0.214 0.198
RSD 2.80% 2.10% 9.50%

Comparison of Tissue Viability
Incubation Positive Control Test substance 
3 min 18.90% 72.50%
1 h 9.90% 10.70%

Applicant's summary and conclusion

Interpretation of results:
Category 1 (corrosive) based on GHS criteria
Conclusions:
Under the study conditions, the test substance was considered as corrosive to skin.
Executive summary:

A study was conducted to determine skin corrosion potential of the test substance using the reconstructed human epidermis (RHE) test method according to OECD Guideline 431, in compliance with GLP. Two tissues of the human skin model EpiDermTM were treated with the test substance for 3 min and 1 h, respectively. Demineralised water was used as negative control and potassium hydroxide (8M) was used as positive control. After treatment, the respective substance was rinsed from the tissues. Then, cell viability of the tissues was evaluated by MTT, which can be reduced to a blue formazan. Formazan production was evaluated by measuring the optical density (OD) of the resulting solution. After treatment with the test substance, the mean value of relative tissue viability was reduced to 72.5% (3 min exposure) and 10.7% (1 h exposure), which qualifies as corrosive. Under the study conditions, the test substance was therefore considered as corrosive to skin (Andres, 2018).