Silver cyanide

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03 October 2013 to 04 November 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-compliant, guideline study, available as an unpublished report.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Report date:

2014

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Deviations:

yes

Remarks:

The control groups were shared and the raw data are filed with another study. This deviation was considered not to affect the purpose or integrity of the study.

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)

Deviations:

yes

Remarks:

The control groups were shared and the raw data are filed with another study. This deviation was considered not to affect the purpose or integrity of the study.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Silver cyanide

EC Number:

208-048-6

EC Name:

Silver cyanide

Cas Number:

506-64-9

Molecular formula:

CAgN

IUPAC Name:

silver(1+) cyanide

Test material form:

other: solid

Details on test material:

- Name of test material: Silver cyanide
- Substance type: not reported
- Physical state: not reported
- Expiration date of the lot/batch: not reported
- Stability under test conditions: not reported
- Storage condition of test material: At room temperature in the dark.

Test animals

Species:

other: EPISKIN (TM) reconstructed human epidermis model

Strain:

other: Not applicable

Details on test animals or test system and environmental conditions:

Not applicable.

Test system

Type of coverage:

other: Topical

Preparation of test site:

other: Not applicable

Vehicle:

unchanged (no vehicle)

Controls:

other: Not applicable

Amount / concentration applied:

- Treatment group: Test carried out in triplicate. Approximately 10 mg of the test item was applied topically, ensuring an even covering, to the epidermis surface which had previously been moistened with 5 µL sterile, distilled water to improve contact between the solid test item and the epidermis.
- Negative control: 10 µL Dulbecco's Phosphate Buffered Saline (DPBS)
- Positive control: 10 µL Sodium Dodecyl Sulphate (SDS) at 5% w/v aqueous solution spread over entire surface of the epidermis using a pipette tip with the process being repeated after 7 minutes.

Duration of treatment / exposure:

- Treatment period: 15 minutes
- Post-exposure incubation: At the end of the exposure period, tissues were rinsed with DPBS with Ca++ and Mg++. Rinsing was achieved by filling and emptying each tissue insert for approximately 40 seconds using a soft stream of DPBS to gently remove any residual test item. The rinsed tissues were transferred to a second column of three wells, each containing 2 mL of maintenance medium, and incubated for 42 hours, at 37°C and 5% CO2 in air.

Observation period:

Not applicable.

Number of animals:

Not applicable.

Details on study design:

Triplicate samples of epidermis tissue were uniformly covered with approximately 10 mg of test item and moistened with 5µL sterile distilled water to improve contact with the solid test item. At the end of the 15 minute exposure period, each tissue was removed and rinsed with DPBS with Ca++ and Mg++. The tissues were then incubated for 42 hours at 37°C and 5% CO2 in air, in wells containing 2 mL maintenance media.

The measurement of tissue viability (cytotoxicity) was measured by means of the colourimetric MTT reduction assay. Cell viability was measured by enzymatic reduction of the yellow MTT tetrazolium salt to a blue formazan salt (by the mitochondrial succinate dehdroganase in viable cells) in the test item treated tissue relative to the negative control using the following procedure. After incubation, the triplicate tissue samples were transferred into three wells each containing 2ml of a 0.3 mg/L MTT solution, care being taken to remove any excess maintenance medium from the bottom of the tissue insert by blotting on absorbent paper. The tissues were incubated for 3 hours at 37ºC, 5% CO2 in air and then the epidermis was carefully separated from the collagen matrix using forceps and both parts placed into 1.5 mL microtubes containing 500 µL of acidified isopropanol. Each tube was plugged and mixed thoroughly on a vortex mixer. The tubes were refrigerated at 1 to 10ºC for 3 days to allow the extraction of formazan crystals out of the MTT-loaded tissues. At the end of the formazan extraction period each tube was thoroughly mixed on a vortex mixer to produce a homogeneous coloured solution. The optical density of the extracted solution was measured at 540 nm against an acidified isopropanol blank.

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

other: other: Percent Relative Viability

Value:

8.8

Remarks on result:

other:

Remarks:

Basis: mean. Time point: 15 minute exposureand 42-hour post-exposure incubation. Max. score: 10.4. Reversibility: no data. Remarks: Negative control item (set at 100). Standard deviation of relative mean viability 1.4 %. (migrated information)

In vivo

Irritant / corrosive response data:

- Viability: The relative mean (n = 3) viability of the treated tissues was 8.8 after a 15-minute exposure period, with standard deviation of 1.4 %
- Optical density: The mean optical density of the treated tissues at 562 nm was 0.084
- Conclusion: Test item is considered to be irritant using the EPISKIN (TM) human epidermis model (viability ≤ 50 %)

Other effects:

- Positive control: The relative mean tissue viability was 10.4 % relative to the negative control and the standard deviation was 4.5 %
- Negative control: The mean optical density was 0.950 and the standard deviation was 0.037.

Any other information on results incl. tables

Direct MTT reduction: The MTT solution containing the test item did not turn blue, indicating that test item did not directly reduce MTT.

The acceptance criteria were satisfied according to the protocol criteria for both the positive control (relative mean viability ≤ 40% and standard deviation ≤ 18%) and negative control (OD562 ≥ 0.6 and standard deviation of individual tissue viability ≤18%). The standard deviation of the triplicate treated tissues was 1.4 % and hence the test item acceptance criterion (≤ 18%) was also satisfied.

Table 1. Mean OD₅₄₀Values and Percentage Viability for Negative Control Item, Positive Control Item and Test Item

Item	OD540of tissue	Mean OD540of triplicate tissues	±SD of OD540	Relative Individual tissue viability (%)	Relative mean viability (%)	±SD of Relative mean viability (%)
Negative Control Item^1	0.931	0.950	0.037	98.0	100*	3.9
	0.927			97.6
	0.993			104.5
Positive Control Item^1	0.102	0.099	0.043	10.7	10.4	4.5
	0.054			5.7
	0.140			14.7
Test Item	0.099	0.084	0.013	10.4	8.8	1.4
	0.078			8.2
	0.074			7.8

SD = Standard deviation

* = The mean viability of the negative control tissues is set at 100%

¹Control group shared with test laboratory project number 41202604

Applicant's summary and conclusion

Interpretation of results:

irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Silver cyanide is considered to be irritant to the skin using the EPISKIN (TM) human epidermis model.

Executive summary:

The skin irritation potential of silver cyanide was evaluated using EPISKIN (TM) reconstructed human epidermis model after a treatment period of 15 minutes followed by a post-exposure period of 42 hours using a colourimetric MTT reduction assay following OECD guideline 439. Silver cyanide considered to be irritant to the skin using the EPISKIN (TM) human epidermis model. The quality criteria required for the acceptance of results in the test were satisfied and the study is considered reliable and relevant for use.