Zinc nitrate

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 431 (In Vitro Skin Corrosion: Human Skin Model Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Zinc nitrate

EC Number:

231-943-8

EC Name:

Zinc nitrate

Cas Number:

7779-88-6

Molecular formula:

HNO3.1/2Zn

IUPAC Name:

zinc nitrate

Test material form:

solid: crystalline

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

skin obtained from plastic surgery from multiple donors

Vehicle:

unchanged (no vehicle)

Details on test system:

TEST SITE
- Area of exposure: approximately 25 mg of the test article + 25 µl tissue culture water (negative control) were applied on the top of each EpiDerm tissue (9mm in diameter)

REMOVAL OF TEST SUBSTANCE
- Washing (if done): at the end of the exposure period, each EpiDerm tissue was rinsed with phosphate buffered saline (PBS)
- Time after start of exposure: test article remained in contact with the EpiDerm tissue for 3 and 60 minutes.

SCORING SYSTEM:
After washing EpiDerm tissue was transferred to a 24 well plate contaiing 300µl MTT solution. Afterwards the tissues were returned to the incubator for a three-hour MTT incubation period. Following MTT incubation period, each EpiDerm tissue was rinsed with PBS and then treated overnight with 2.0 ml of extractant solution (isopropanol) per well. The absorbancy of an aliquot of the extracted MTT formazan was measured at 540nm using a microplate reader.

Analysis of data:
The mean absorbance value for each time point was calculated from the optical density (OD) of the duplicate samples and expressed as percent viability for each sample using the following formula:
% viability= 100x(OD sample/OD negative control)

Quality controls: negative controls meets the acceptance criterion if the mean OD of the 2 tissues each time point is greater than or equal to 0.8. The positive controls meets the acceptance criterion if the mean relative tissue viability at the 3 minute time point is less than or equal to 30%
Inter-tissue viability meets the acceptance criterion if the difference between two identically treated tissues is no greater than 30%

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied: 25 mg of the test article, plus 25 ul tissue culture water were applied to the top of each EpiDerm tissue

Duration of treatment / exposure:

3 and 60 min

Test system

Details on study design:

TEST SITE
- Area of exposure: approximately 25 mg of the test article + 25 µl tissue culture water (negative control) were applied on the top of each EpiDerm tissue (9mm in diameter)

REMOVAL OF TEST SUBSTANCE
- Washing (if done): at the end of the exposure period, each EpiDerm tissue was rinsed with phosphate buffered saline (PBS)
- Time after start of exposure: test article remained in contact with the EpiDerm tissue for 3 and 60 minutes.

SCORING SYSTEM:
After washing EpiDerm tissue was transferred to a 24 well plate contaiing 300µl MTT solution. Afterwards the tissues were returned to the incubator for a three-hour MTT incubation period. Following MTT incubation period, each EpiDerm tissue was rinsed with PBS and then treated overnight with 2.0 ml of extractant solution (isopropanol) per well. The absorbancy of an aliquot of the extracted MTT formazan was measured at 540nm using a microplate reader.

Analysis of data:
The mean absorbance value for each time point was calculated from the optical density (OD) of the duplicate samples and expressed as percent viability for each sample using the following formula:
% viability= 100x(OD sample/OD negative control)

Quality controls: negative controls meets the acceptance criterion if the mean OD of the 2 tissues each time point is greater than or equal to 0.8. The positive controls meets the acceptance criterion if the mean relative tissue viability at the 3 minute time point is less than or equal to 30%
Inter-tissue viability meets the acceptance criterion if the difference between two identically treated tissues is no greater than 30%

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

after 3 min

Value:

79.5

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Results 2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

after 60 min

Value:

49

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

In this in vitro EPIDERM model test with zinc nitrate hexahydrate, the results indicate that the test item is not a skin corrosive.

Executive summary:

A study was conducted to predict and classify the skin corrosivity potential of zinc nitrate hexahydrate by using a three-dimensional human epidermis model (OECD 431). MatTek EpiDerm tissue samples were treated in duplicate with the test article, negative control and positive control for 3 minutes and 60 minutes. Following treatment, the viability of the tissues was determined using MTT uptake and conversion, and the absorbance of each sample was measured at 540nm. The viability was then expressed as a percent of control values.

In this in vitro EPIDERM model test with zinc nitrate hexahydrate, the results indicate that the test item is not a skin corrosive.