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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:
weight of evidence
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 431 (In Vitro Skin Corrosion: Human Skin Model Test)
Deviations:
no
Qualifier:
according to
Guideline:
other: B.40 BIS (In vitro Skin Corrosion: Human Skin Model Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: oil

In vitro test system

Test system:
other: Commercially available Epi-200-Kit
Source species:
human
Cell type:
non-transformed keratinocytes
Details on test system:
Epi-200 tissues were procured from MatTek In Vitro Life Science Laboratories.
Day of delivery: 08 Oct 2013
Batch EPI-200-CORR: 18381

Chemicals and Media:
- MTT reagent: Contains 1mg/mL 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide, which can be reduced to a blue formazan. Prepared as concentrate (5mg/mL in DPBS buffer, stored at -20 °C).
For the pre-test, the concentration was thawed and diluted with serum-free MEM medium directly before use.
For the main study, the concentrate was thawed and diluted with assay medium directly before use.

Isopropanol 99,9%, batch 3100602 used as exctracting solvent for formazan

The EpiDerm tissue consists of normal, human-derived epidermal keratinocytes which have been cultured to form a multi-layered, highly differentiated model of the human epiderms. It consists of organised 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 EpiDerm tissues are cultured on specially prepared cell cultures inserts. Negative control: Deionised H2O Positive control: KOH, solution in deionised H2O containing 8.0 mol/L.

Results and discussion

In vitro

Results
Irritation / corrosion parameter:
dye content (µg/disc)
Value:
ca. 98.1
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
no indication of irritation
Other effects / acceptance of results:
The photometric absorption of the negative controls was considered as 100%. For the mean of the three replicates of test item and positive control. formazan production was calculated as % photometric absorption compared with the negative control.
See table below for assessment

Any other information on results incl. tables

Assessment:

 % Formazan productionafter 3 min. incubation time % Formazan productionafter 1 h incubation time  Assessment 
 < 50% of negative control  irrelevant  Corrosive!
 > = 50% of negative control  < 15% of negative control  Corrosive!
 >= 50% of negative control  >= 15% of negative control  not corrosive

Results:

The absorption values of negative control, test item and positive control are given in the following table:

Negative Control   Test Item  Positive Control  Incubation time
Tissue 1  Tissue 2  Tissue 1  Tissue 2  Tissue 1  Tissue 2     
 2.202  1.956  2.067  2.075  0.443  0.472     3 min
 2.199  1.975  2.048  2.026  0.452  0.465     3 min
 2.166  2.074  2.038  2.079  0.452  0.459  3 min   
 1.948  2.014  1.716  1.875  0.199  0.205     1 hour
 1.986  1.924  1.750  1.916  0.198  0.203     1 hour
 1.986  2.016  1.756  1.909  0.194  0.204     1 hour
 Mean  Mean  Mean  
 2.095  2.056  0.457  3 min
 1.979  1.820  0.201  1 hour

Validity:

The criterion for optical density of the negative control (> 0.8) was fulfilled: optical density was 2.095 (3 minutes) resp. 1.979 (1 hour). The positive control showed a clear corrosive effect: the value of the three-minuteexperiment was 21.8% and the value of the one-hour-experiment was 10.1%. Values for negative control and for positive control were within the range of historical data of the test facility (see Annex 2: Comparison with Historical Data, page 17). Therefore, the experiment is considered valid.

Discussion:

The test item is considered not corrosive. After three minutes treatment, the relative absorbance values were decreased to 98.1%. This value is well above the threshold for corrosivity (50%). After one hour treatment relative absorbance values were reduced to 92.0%. This value is well above the threshold for corrosivity (15%). In the guideline, values greater or equal to the threshold are considered as “non-corrosive to skin”. The values of the negative control were well above the required acceptability criterion of mean OD > 0.8 for both treatment intervals thus showing the quality of the tissues. The positive control induced a decrease in the relative absorbance as compared to the negative control to 21.8% for the three minutes treatment interval and 10.1% for the one hour treatment interval thus ensuring the validity of the test system. For these reasons, the result of the test is considered valid.

Applicant's summary and conclusion

Interpretation of results:
other: non-corrosive (Skin Irrit. 2 or not classified according to Regulation (EC) No 1272/2008)
Conclusions:
Under the conditions of the test, the source substance (CAS 126-57-8) was shown to have no corrosive potential towards reconstructed human epidermis tissue in the EpiDerm model. The result does not allow for the non-classification or classification as irritant of the test substance and therefore further evaluation and/or data generation is required.