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Diss Factsheets

Administrative data

Endpoint:
skin irritation: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2010-03-03 to 2010-03-08
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 guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
other: Commission Regulation (EC) No. 440/2008 B.46 (draft)
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: ECVAM international validation study on in vitro tests for acute skin irritation (Altern Lab Anim. 2007 Dec; 35 (6):559-601)
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: OECD Guideline for the Testing of Chemicals; Draft proposal for a new guideline, in vitro skin irritation: Reconstructed Human Epidermis (RhE) Test method, 11 December 2009, Vers. 4.
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
signed 2009-03-30

Test material

Constituent 1
Chemical structure
Reference substance name:
Divanadium trioxide
EC Number:
215-230-9
EC Name:
Divanadium trioxide
Cas Number:
1314-34-7
Molecular formula:
O3V2
IUPAC Name:
Divanadium trioxide
Test material form:
other: granules
Details on test material:
- Name of test material (as cited in study report): Divanadium trioxide
- Trivial name: Vanadium trioxide
- Molecular formula: V2O3
- Molecular weight: 149.88 g/mol
- Physical state: Solid, black granules
- Storage condition of test material: At room temperature, protected from moisture

Test animals

Details on test animals or test system and environmental conditions:
Not applicable - This was a in vitro study without any test animals.

Test system

Vehicle:
water
Amount / concentration applied:
TEST MATERIAL
- Amount(s) applied (volume or weight with unit): Approx. 15 mg of the test item were applied to each of triplicate tissues.
No further information on the amount/concentration applied was stated.
Duration of treatment / exposure:
15+/- 1 min
Observation period:
not applicable
Number of animals:
not applicable
Details on study design:
CELL CULTURE
EpiSkin TM kits (Lot No.: 10-EKIN-007) were purchased from Skinethic Laboratories (06000 Nice, France). The EpiSkin TM tissue consists of normal, human-derived epidermal keratinocytes that have been cultured to form a multilayered, highly differentiated model of the human epidermis. It 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. The EpiSkin TM tissues (surface 0.38 cm^2) are cultured on specially prepared cell culture inserts.
EpiSkin TM tissues were shipped with ice packs on medium-supplemented agarose gels in a 12-well plate. On day of experiment EpiSkin TM tissues were transferred to 12-well plates with maintenance medium.

TREATMENT:
The negative control (deionised water (lot no. 1.3.10, produced in-house; 15 µL were applied to each of triplicate tissues) and positive control (5% sodium lauryl sulphate (lot no. 1353471 51508322; Fluka, Sigma-Aldrich, 89555 Steinheim, Germany) solution in deionised water, prepared freshly prior to the performance of the experiment; 15 µL were applied to each of triplicate tissues), and the test item were added into the insert atop the concerning EpiSkin TM triplicate tissues. Additionally, the test item tissues were wetted with 15 µl of deionised water. The plates were placed into the incubator for 15+/- 1 min at 37 +/- 1.5 °C, 5 +/- 0.5 % CO2.
After the end of the treatment interval the inserts were removed immediately from the plate. Using a wash bottle the tissues were gently rinsed with PBS to remove any residual test material. Excess PBS was removed by gently shaking the inserts and blotting the bottom with blotting paper. The inserts were placed in the plates with 2 mL maintenance medium. The tissues were incubated for 42 +/- 1 hour at 37 +/- 1.5 °C, 5 +/- 0.5 % CO2.

MTT ASSAY:
Cell viability is measured by dehydrogenase conversion of MTT [(3-4,5-dimethyl thiazole 2-yl) 2,5-diphenyl-tetrazoliumbromide], present in cell mitochondria, into a blue formazan salt that is quantitatively measured after extraction from tissues (Faller, C., Bracher, M., Dami, N., Roguet, R., 2002. Predictive ability of reconstructed human epidermis equivalents for assessment of skin irritation of cosmetics. Toxicology in vitro 16 (5), 557-552.).The percent reduction of cell viablity in comparison of untreated negative controls is used to predict skin irritation potential.
After the treatment procedure (42 hours) was completed for all tissues of each time point cell culture inserts were transferred from the holding plates to plates containing 2 mL assay medium containing 0.3 mg/mL MTT per well. After a 3 hour incubation period (37 +/- 1.5 °C, 5 +/- 0.5 % CO2) MTT solution was aspirated from the wells and the wells were rinsed three times with PBS. Tissues samples were cut out of the inserts with a biopsy punch and transferred into plastic vials. The tissue samples were immersed into extractant solution by gently pipetting 0.5 mL extractant solution (isopropanol) into each vial. The tissue samples were completely covered by isopropanol. The vials were sealed to inhibit isopropanol evaporation. The formazan salt was extracted for approx. 72 hours in the refrigerator.
Per each tissue sample 2 X 200 µL aliquots of the formazan blue solution were transferred into a 96-well flat bottom microtiter plate. OD was read in a microplate reader (Versamax® Molecular Devices, 85737 Ismaning, Germany) at 570 nm without reference filter. Mean values were calculated from the 2 wells per tissue sample.

EVALUATION OF RESULTS:
The mean OD of the three negative control tissues was calculated. This value corresponds to 100% tissue viability in the current test. For each individual tissue treated with the test item or the positive control the individual relative tissue viability is calculated according to the following formula:
Relative viability (%) = [OD test item/ OD negative control] * 100
For the test item and the positive control the mean relative viability +/- standard deviation of the three individual tissues are calculated and used for classification according to the following prediction model:
For the current test, an irritation potential of a test item according to EU classification R38 is predicted if the mean relative tissue viablity of three individual tissues is reduced below 50 % of the negative control.

ACCEPTABILITY OF THE ASSAY:
The absolute OD 570 nm of the negative control tissues in the MTT test is an indicator of tissue viability obtained after the shipping and storing procedure and under specific conditions of the assay. Tissue viability is meeting the acceptance criterion if the mean OD of the three tissues is ≥0.6 till ≤ 1.5.
An assay is meeting the acceptance criterion if mean relative tissue viability of the positive control is ≤ 40%.
The standard deviations in between tissues of the same treatment group should be ≤ 18%.

The data of the quality control (determined by Skinethic Laboratories, 06000 Nice, France) of the respecitve EpiSkin TM lot is mentioned below under "Attached background material" (the acceptance limit of the IC50 should be in the between 1.0 and 3.0 mg/L after 18 hours treatment with SLS).

TEST FOR DIRECT MTT REDUCTION.
For correct interpretation of results it was necessary to assess the ability of the test item to directly reduce MTT. To test for this ability approximately 15 mg of the test item were added to 1 mL of MTT solution and the mixture was incubated in the dark at room temperature for 60 minutes. Untreated MTT medium was used as control. If the MTT solution colour turned blue/purple, the test item was presumed to have reduced the MTT.
A colour change was not observed.

Results and discussion

In vitro

Results
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
1
Value:
86.2
Negative controls validity:
valid
Positive controls validity:
valid
Other effects / acceptance of results:
After treatment with divanadium trioxide, the relative absorbance values decreased to 86.2%. This value is well above the threshold for irritancy of ≤ 50 %. Therefore, the test item is not considered to possess an irritant potential.

Any other information on results incl. tables

Results after treatment with divanadium trioxide

 

Dose group

Treatment Interval

Absorbance 570 nm
Tissue 1

Absor-bance 570 nm
Tissue 2

Absorbance 570 nm
Tissue 3

Mean Absorbance of 3 Tissues

Absorbance [%] Tissue 1, 2 + 3

Rel. Standard Deviation

Rel. Absorbance

[% of Negative Control]

Negative Control

15 min

0.878

0.819

0.873

0.857

102.5
95.6
101.9

3.8

100.0

Positive Control

15 min

0.293

0.209

0.203

0.235

34.2
24.4
23.7

5.9

27.4

Divana-dium trioxide

15 min

0.790

0.712

0.714

0.739

92.1
83.1
83.4

5.1

86.2

Optical evaluation of the MTT-reducing capacity of the test item after 1 hour incubation with MTT-reagent did not show blue colour.

Historical data:

Positive Control

Negative Control

Number of Studies

73

Number of Studies

73

Period

July 2007 - March 2010

Period

July 2007 - March 2010

Mean Viability

16.5 %

Mean OD

1.081

Standard Deviation

11.0%

Standard Deviation

0.262

Range of Viabilities

3% - 36%

Range of ODs

0.7 – 1.6*

* The upper OD value is outside of the range of 0.6 - 1.5 recommended by the OECD guideline. Nevertheless since the OD value is only slightly above the required range, the historical data can still be considered as valid.

Applicant's summary and conclusion

Interpretation of results:
not irritating
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
After treatment with divanadium trioxide, the relative absorbance values decreased to 86.2%. This value is well above the threshold for irritancy of ≤ 50 %. Therefore, the test item is not considered to possess an irritant potential. The test item is not classified as skin irritant according to Directive 67/548/EEC and according to regulation (EC) No.: 1272/2008.

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