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Toxicological information

Skin irritation / corrosion

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Administrative data

Endpoint:
skin irritation: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11 June 2010 - 18 June 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study was conducted according to official EC and OECD test guidelines, and in compliance with GLP.

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)
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Triiron phosphide
EC Number:
234-682-8
EC Name:
Triiron phosphide
Cas Number:
12023-53-9
Molecular formula:
Fe3P
IUPAC Name:
Iron (3+); phosphorous (3-)
Details on test material:
- Name of test material (as cited in study report): Ferrophosphorus (Fe3P)
- Substance type: inorganic
- Physical state: black powder (solid)
- Analytical purity: Fe: 82.7%, P: 15.7%
- Lot/batch No.: 1068487
- Expiration date of the lot/batch: 15 February 2011
- Storage condition of test material: room temperature

In vitro test system

Test system:
human skin model
Remarks:
EpiDerm™ three-dimensional human skin model
Source species:
human
Cell type:
non-transformed keratinocytes
Vehicle:
unchanged (no vehicle)
Details on test system:
TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37±1°C
- Temperature of post-treatment incubation (if applicable): 37±1°C

REMOVAL OF TEST MATERIAL AND CONTROLS
- Volume and number of washing steps: After the required dosing period, each tissue was rinsed with Dulbecco’s Phosphate Buffered Saline (DPBS), for a minimum of 20 rinses, and then blotted on absorbent paper. The inserts were then transferred to the holding plate. After rinsing with DPBS and gently swabbing with a sterile swab, a small quantity of the test material remained on the surface of each of the tissues treated with test material Ferrophosphorus (Fe3P).
- Post-incubation: transferred to the MTT assay plate which was then incubated for three hours at 37±1°C in a humidified atmosphere of 5% CO2 in air. After three hours, the tissues were rinsed with DPBS and transferred to 1 ml per well extraction solution (isopropanol) in 24-well plates. A further 1 ml was then added to each insert. The tissues were extracted overnight at room temperature, without shaking. After the extraction period, triplicate 200 μl aliquots of extractant from each tissue were pipetted into the wells of flat-bottomed 96-well plates and the absorbance read at 540 nm.

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 1 mL of 1 mg/mL MTT solution in duplicate
- Incubation time: 3 minutes and 1 hour
- Spectrophotometer: yes
- Wavelength: 540 nm

NUMBER OF REPLICATE TISSUES: duplicate tissues; triplicate measurements

PREDICTION MODEL / DECISION CRITERIA
If the tissue viability from the three minute exposure is less than 50% of the negative control value, then the sample is classified as corrosive. If the tissue viability from the three minute exposure is greater than or equal to 50% of the negative control value but the one hour value is less than 15% of the negative control value, the sample is classified as corrosive. If the tissue viability from the three minute exposure is greater than or equal to 50% and the one hour value is greater than or equal to 15% of the negative control value, then the sample is classified as non-corrosive.
Control samples:
yes, concurrent negative control
yes, concurrent positive control
yes, concurrent MTT non-specific colour control
Amount/concentration applied:
Nominal weights of 25 mg of the test material was dispensed over each tissue. The test material was then wetted with 25 μl purified water.
The positive and negative controls were in liquid form and were applied by dispensing a volume of 50 μl over each tissue using a pipette.
Duration of treatment / exposure:
3 minutes; 1 hour
Duration of post-treatment incubation (if applicable):
3 hours
Number of replicates:
duplicate tissues; triplicate measurements

Results and discussion

In vitro

Resultsopen allclose all
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
1 hour
Value:
97.5
Vehicle controls validity:
not examined
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: non-corrosive
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
3 minutes
Value:
109.1
Vehicle controls validity:
not examined
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: non-corrosive
Other effects / acceptance of results:
Negative control:
The mean optical density of each duplicate negative control value for the three minute and one hour contact were 1.707 and 1.805, respectively. Both values were above the minimum assay acceptance value of 0.8.

Positive control:
The mean relative tissue viability of the positive control, 8.0 N potassium hydroxide, for the one hour application was 7.0%. This value was below the maximum acceptable value of 15%.

Inter-tissue viability difference:
The coefficient of variation (CV) was not applicable for the positive control one hour application, as the mean percentage viability, 7.0%, was below the 20% - 100 % viability range. All other values did not exceed the CV value of 0.3.

Any other information on results incl. tables

Results

Reduction of MTT by test material

After the one hour incubation, the colour of the test material, Ferrophophorus (Fe3P) / MTT mixture (orange with black powder) and MTT solution control (orange) remained unchanged, from the start of incubation. Therefore, the test material had not reduced the MTT.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
The test material, Ferrophosphorus (Fe3P), elicited a mean tissue viability of 109.1% for three minute contact and 97.5% for one hour contact and was non-corrosive in the Epiderm™ Skin Corrosivity test.