Cesium acetate

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 8 Dec, 2010 to 21 Dec, 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Test guideline 1

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Cesium acetate

EC Number:

222-248-0

EC Name:

Cesium acetate

Cas Number:

3396-11-0

Molecular formula:

C2H4O2.Cs

IUPAC Name:

cesium acetate

Test material form:

liquid

Details on test material:

- Name of test material (as cited in study report): Cesium acetate (liquid)
- Physical state: Clear colourless liquid
- Analytical purity: 83%
- Storage condition of test material: Room temperature in the dark over silica gel

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Test system

Amount / concentration applied:

10 µL

Duration of treatment / exposure:

15 min followed by a post-exposure incubation period of 42 h

Details on study design:

-Application of the test substance and rinsing (Day 1): 2 mL of maintenance medium, warmed to approx 37°C, was pipetted into the second column of 3 wells of the 12-well plate. Triplicate tissues were treated with the test substance for an exposure period of 15 min. The test substance was applied topically to the corresponding tissues ensuring uniform covering. 10 µL of the test substance was applied to the epidermis surface. Triplicate tissues treated with 10 µL of PBS served as the negative controls and triplicate tissues treated with 10 µL of SDS 50% w/v served as the positive controls. To ensure satisfactory contact with the positive control substance the SDS solution was spread over the entire surface of the epidermis using a pipette tip (taking particular care to cover the centre). After 7 min contact time the SDS solution was re-spread with a pipette tip to maintain the distribution of the SDS for the remainder of the contact period. The plate(s) were kept in the biological safety cabinet at room temperature for approx 15 min. At the end of the exposure period, each tissue was removed from the well using forceps and rinsed using a wash bottle containing PBS with Ca++ and Mg++. Rinsing was achieved by filling and emptying each tissue insert for approx 40 sec using a constant soft stream of PBS to gently remove any residual test substance. The rinsed tissues were transferred to the second column of 3 wells containing 2 mL of maintenance medium in each well. The rinsed tissues were incubated at 37°C, 5% CO2 in air for approx 42 h.
-MTT loading/formazan extraction (Day 3): Following the 42-h post-exposure incubation period each 12-well plate was placed onto a plate shaker for approx 15 min to homogenise the released mediators in the maintenance medium. 1.6 mL of the maintenance medium from beneath each tissue was transferred to pre-labelled micro tubes and stored in a freezer at -14 to -30°C for possible inflammatory mediator determination. 2 mL of a 0.3 mg/mL MTT solution, freshly prepared in assay medium, was pipetted into the third column of 3 wells of the 12 well plate(s). The tissues were transferred to the MTT filled wells, being careful to remove any excess maintenance medium from the bottom of the tissue insert by blotting on absorbent paper. The tissues were incubated for 3 h at 37°C, 5% CO2 in air. At the end of the 3-h incubation period each tissue was placed onto absorbent paper to dry. A total biopsy of the epidermis was made using the EPISKIN™ biopsy punch. The epidermis was carefully separated from the collagen matrix using forceps and both parts (epidermis and collagen matrix) placed into labelled 1.5 mL micro tubes containing 500 µL of acidified isopropanol, ensuring that both the epidermis and collagen matrix were fully immersed. Each tube was plugged to prevent evaporation and mixed thoroughly on a vortex mixer. The tubes were refrigerated at 1 to 10°C until Day 6 of the experiment, allowing the extraction of formazan crystals out of the MTT-loaded tissues.
-Absorbance/optical density measurements (Day 6): At the end of the formazan extraction period each tube was mixed thoroughly on a vortex mixer to produce a homogenous coloured solution. For each tissue, duplicate 200 µL samples were transferred to the appropriate wells of a pre-labeled 96-well plate. 200 µL of acidified isopropanol alone was added to the two wells designated as 'blanks'. The optical density was measured (quantitative viability analysis) at 540 nm (without a reference filter).

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

15 minutes

Value:

97.5

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Any other information on results incl. tables

Quality criteria: The relative mean tissue viability for the positive control treated tissues was ≤40% relative to the negative control treated tissues and the SD value of the percentage viability was ≤18%. The positive control acceptance criterion was therefore satisfied. The mean OD540 for the negative control treated tissues was ≥0.6 and the SD value of the percentage viability was ≤18%. The negative control acceptance criterion was therefore satisfied. The SD calculated from individual percentage tissue viabilities of the three identically treated tissues was ≤18%. The test substance acceptance criterion was therefore satisfied.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the study conditions, the test substance was considered to be non-irritating to skin.

Executive summary:

A study was conducted to evaluate the skin irritation potential of the test substance in brine form according to OECD Guideline 439 and EU Method B.46, in compliance with GLP. Triplicate tissue samples were treated with the substance for an exposure period of 15 min. The tissues were then rinsed before incubating for approximately 42 h. At the end of the post-exposure incubation period, the tissues were taken for MTT Ioading. The maintenance medium from beneath each tissue was transferred to pre-labelled microtubes and stored in a freezer for possible inflammatory mediator determination. After MTT loading, a total biopsy of each epidermis was made and placed into microtubes containing acidified isopropanol for extraction of formazan crystals out of the MTT-loaded tissues. At the end of the formazan extraction period, the tubes were mixed thoroughly and duplicate 200 µL samples were transferred to the appropriate wells of a pre-labelled 96-well plate. The optical density was measured at 540 nm. The relative mean viability of the treated tissues was 97.9% after the 15 min exposure period. Under the study conditions, the test substance was therefore considered to be non-irritating to skin (Warren, 2011).