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Toxicological information

Skin irritation / corrosion

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Administrative data

Endpoint:
skin corrosion: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
June 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
liquid
Specific details on test material used for the study:
STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature
- Stability under test conditions: stable

In vitro test system

Test system:
human skin model
Source species:
human
Cell type:
non-transformed keratinocytes
Cell source:
foreskin from a single donor
Source strain:
not specified
Justification for test system used:
Standard test system for OECD 431
Vehicle:
unchanged (no vehicle)
Details on test system:
TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: for the 3 minutes exposure: room temperature, 1h exposure: 37°C
- Temperature of post-treatment incubation (if applicable): 37°C
DYE BINDING METHOD
- Dye used in the dye-binding assay: [none / MTT / Sulforhodamine B / other:] MTT
- Spectrophotometer: SunriseTM Absorbance Reader
- Wavelength: 570nm
- Assay medium: EPI-100-ASY assay medium
- MTT diluent: DMEM
- Washing buffer: PBD
- Extractin agent: Isopropanol
NUMBER OF INDEPENDENT TESTING RUNS / EXPERIMENTS TO DERIVE FINAL PREDICTION: 2
PREDICTION MODEL / DECISION CRITERIA (choose relevant statement)
- The test substance is considered to be corrosive to skin if the mean relative tissue viability after the 3-minute treatment with a test material is decreased below 50%. In addition, materials with a viability of more than 50% after the 3-minute treatment are considered to be corrosive if the mean relative tissue viability after a 1-hour treatment with test material is decreased below 15%.
Control samples:
yes, concurrent negative control
yes, concurrent positive control
Amount/concentration applied:
50µl
Duration of treatment / exposure:
3 min and 1h
Number of replicates:
2

Results and discussion

In vitro

Resultsopen allclose all
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
Mean (3 min exposure)
Value:
66.5
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
positive indication of irritation
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
Mean (1h exposure)
Value:
4.7
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
positive indication of irritation
Other effects / acceptance of results:
The viability of the cells after 3 minutes of exposure is higher than 50 %, but the viability of the cells after an exposure of 1 hour is lower than 15%. Hence, According to the decision criteria of the OECD Guideline 431 for evaluation of results of SCT, the substance is corrosive to skin.

Applicant's summary and conclusion

Interpretation of results:
Category 1 (corrosive) based on GHS criteria
Conclusions:
Based on the results of this in-vitro test, it was concluded that the test substance shows a skin corrosion potential in the EpiDerm in vitro irritation and corrosion test strategy under the test conditions chosen.
Executive summary:

The objective of this in-vitro study was to assess the skin irritation and corrosion potential of Phenyl acid phosphate. Using the methods currently available, a single in vitro assay is not sufficient to

cover the full range of skin irritating/corrosion potential.

Therefore, two in vitro assays were part of this in vitro skin irritation and corrosion test strategy:

The Skin Corrosion Test (SCT) and Skin Irritation Test (SIT).

The potential of the test substance to cause dermal corrosion/irritation was assessed by a single topical application of 50 μL (corrosion test) or 30 μL (irritation test) undiluted test substance to a reconstructed three-dimensional human epidermis model (EpiDerm™).

For the corrosion test, two EpiDerm™ tissues were incubated with the test substance for 3 minutes and 1 hour, each. The irritation test was performed with three EpiDerm™ tissues, which were incubated with the test substance for 1 hour followed by a 42-hour post-incubation period. Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation by using a colorimetric test. The reduction of mitochondrial dehydrogenase activity measured by reduced formazan production after incubation with a tetrazolium salt (MTT) was chosen as endpoint. The formazan production of the epidermal tissues treated with the test substance is compared to that of negative control tissues. The quotient of the values indicates the relative tissue viability.

The following results were obtained in the EpiDerm™ skin corrosion/irritation test:

The test substance is not able to reduce MTT directly.

Results of the Corrosion Test (SCT):

The relative mean viability of the tissues treated with the test substance determined after an exposure period of 3 minutes was 66.5%, and it was 4.7% after an exposure period of 1 hour.

Results of the Irritation Test (SIT):

The relative mean viability of the tissues treated with the test substance determined after an exposure period of 1 hour with an about 42-hour post-incubation was 2.1%.

The tissues treated with the test substance (SCT (1-hour exposure) and SIT) were pale yellow discolored (no visible compound residues left).

Based on these results, it was concluded that Phenyl acid phosphate shows a skin corrosion potential in the EpiDerm™ in vitro skin irritation and corrosion test strategy under the test conditions chosen.