Zinc acrylate

Skin irritation / corrosion

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 guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)

Version / remarks:

Adopted Jul. 29, 2016

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

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. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Zinc acrylate

EC Number:

238-692-3

EC Name:

Zinc acrylate

Cas Number:

14643-87-9

Molecular formula:

C3H4O2.1/2Zn

IUPAC Name:

zinc acrylate

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

Results

Results 1

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

Results 2

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).