Iron cobalt black spinel

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10 February 2017 - 20 July 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

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)

Version / remarks:

28 July 2015

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

6 July 2012

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

BASF SE Experimental Toxicology and Ecology 67056 Ludwigshafen, Germany

Test material

Test material information

Constituent 1

Reference substance name:

Iron cobalt black spinel

EC Number:

269-102-2

EC Name:

Iron cobalt black spinel

Cas Number:

68187-50-8

Molecular formula:

CoFe2O4

IUPAC Name:

Iron cobalt spinel

Test material form:

solid

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EpiDerm™ 200 kit, 24 EPI-200 tissues (human reconstructed epidermis): surface 0.6 cm²
- Tissue batch number: 23393
- Production date: 15 February 2017

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: room temperature (first 25 min) and at 37°C (for further 35 min)
- Temperature of post-treatment incubation: 37°C

REMOVAL OF TEST MATERIAL AND CONTROLS
- washing steps: washed with sterile PBS
- Observable damage in the tissue due to washing: no, but minimal compound residues remained on the tissues treated with the test substance after the washing procedure
- Modifications to validated SOP: no

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 1 mg/mL
- Incubation time: 3 hours
- Spectrophotometer: SunriseTM Absorbance Reader
- Wavelength: 570 nm

FUNCTIONAL MODEL CONDITIONS
- Viability: OD [540-570] = 1.52 ± 0.144
- Barrier function: ET-50 = 5.55 h
- Contamination: none

NUMBER OF REPLICATE TISSUES: 3

CONTROL TISSUES USED IN CASE OF MTT DIRECT INTERFERENCE
- killed tissues
- Procedure used to prepare the killed tissues: freeze-killed
- N. of replicates : 3

PREDICTION MODEL / DECISION CRITERIA (choose relevant statement)
A chemical is considered as "irritant" if the mean relative tissue viability with a test material is less than or equal to 50%.
Mean tissue viability (% of negative control): < 45 (irritant)
Mean tissue viability (% of negative control): 45-55 (borderline)
Mean tissue viability (% of negative control): > 55 (nin-irritant)
The “borderline“ evaluation (50 ± 5%) was statistically determined by using historic BASF data and hence considers the variance of the test method. This evaluation is confirming the borderline range provided in OECD Guideline 439.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

yes, concurrent MTT non-specific colour control

Amount/concentration applied:

TEST MATERIAL
- Amount applied:
25 µL sterile PBS was applied first. Thereafter, a bulk volume of ca. 25 µL (ca. 17 mg) solid test material was applied with a sharp spoon and homogeneously distributed together.

NEGATIVE CONTROL
- Amount applied: 30 µL sterile PBS

POSITIVE CONTROL
- Amount applied: 30 µL 5% SDS

Duration of treatment / exposure:

1 hour

Duration of post-treatment incubation (if applicable):

42 hours

Number of replicates:

3

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

1.Experiment /1 hour treatment

Value:

76.7

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

100%

Positive controls validity:

valid

Remarks:

2.7%

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

- OTHER EFFECTS:
- Visible damage on test system: none
- Direct-MTT reduction: Due to the intense color of the test substance, it was not possible to evaluate whether the test substance is able to directly reduce MTT.
- Colour interference with MTT: none (result from pre-test)

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: Yes [1.902]
Tissue viability is acceptable if the mean OD570 of the NC is > 0.8. The mean OD570 of the NC should not exceed 2.8.
- Acceptance criteria met for positive control: Yes
5% SDS is used as PC and reflects the sensitivity of the tissues used in the test conditions. A viability of < 20% is acceptable
- Acceptance criteria met for variability between replicate measurements: Yes
For every treatment, three tissues are treated in parallel. The inter-tissue variability is considered to be acceptable if the SD of % viability is < 18%.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met