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Skin irritation / corrosion

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skin irritation / corrosion
in vitro
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Recent GLP compliant study with detailed test report

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 431 (In Vitro Skin Corrosion: Human Skin Model Test)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Reference substance name:
Test material form:
liquid: viscous
Details on test material:
Batch No. P23_11_12 + P25_07_13
Purity > 99%
Production date 23 Nov. 2012
Condition at receipt: room temperature, in proper conditions

In vitro test system

Test system:
human skin model
Source species:
other: skin model EpiDerm
Cell type:
other: skin model EpiDerm
Cell source:
other: skin model EpiDerm
Source strain:
other: skin model EpiDerm
Control samples:
yes, concurrent negative control
yes, concurrent positive control

Test animals

other: No test animals were used, as it concerns an in vitro test
other: not applicable (in vitro test)

Test system

unchanged (no vehicle)
other: Deionised water was used as negative control, KOH was used as a positive control
Amount / concentration applied:
The liquid test item was applied without preparation (50 microL to each well)
Duration of treatment / exposure:
Three minutes and one hour, respectively
Observation period:
The tissues were incubated with MTT reagent for three hours. After this time, the MTT reagent was aspirated and replaced by DPBS buffer. This was then aspirated, too, and replaced several times. At last, each insert was thoroughly dried and set into an empty, pre-warmed plate. Into each well, 2 mL isopropanole were pipetted. The plate was then covered with Parafilm and left to stand overnight at room temperature.
Number of animals:
Not applicable (in vitro test)
Details on study design:
After incubation overnight, the inserts in which formazan had been produced over night were pierced with an injection needle, taking care that all colour was extracted. The inserts were then discarded and the content of each well was thoroughly mixed in order to achieve homogenenisation. From each well, three replicates with 200 microL Solution (each) were pipetted into a 96-well plate which was read in a plate spectral photometer at 570 nm.

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 negative control.

Results and discussion

In vitro

Irritation / corrosion parameter:
other: absorption
Run / experiment:
Formazan production
ca. 1.727
Vehicle controls validity:
not applicable
Negative controls validity:
Positive controls validity:
Remarks on result:
no indication of irritation

Any other information on results incl. tables

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

Absorption values


Negative Control Test item Positive control Incubation
Tissue 1 Tissue 2 Tissue 1 Tissue 2 Tissue 1 Tissue 2  
1,814 2,046 1,824 1,665 0,587 0,636 3 min
1,778 1,98 1,784 1,664 0,559 0,683
1,768 1,953 1,764 1,66 0,598 0,57
2,067 1,724 1,656 1,685 0,158 0,152 1 hour
1,994 1,962 1,758 1,825 0,172 0,172
2,085 2,065 1,795 1,837 0,185 0,174
Mean Mean Mean  
1,89 1,727 0,606 3 min
1,983 1,759 0,169 1 hour

For the test item and the positive control, the following percentage values of mean formazan production were calculated in comparison to the mean of the negative controls.

Test item Positive control Incubation
91,40% 32,00% 3 min
88,70% 8,50% 1 hour


Applicant's summary and conclusion

Interpretation of results:
other: not corrosive
Criteria used for interpretation of results: EU
Executive summary:

The skin corrosion potential of the substance was assessed via an in vitro test according to OECD and GLP guidelines, using the Human Skin Model test.

Two tissues of the human skin model EpiDerm were treated with the test substance for three minutes and one hour, respectively.

50 μL of the liquid test item were applied to each tissue and spread to match the tissue size. Deionised water was used as negative control, 8m KOH was used as positive control.

After treatment, the respective substance was rinsed from the tissue; then, cell viability of the tissues was evaluated by addition of MTT which can be reduced to a blue formazan. Formazan production was measured by measuring the optical density (OD) of the resulting solution. After treatment with the negative control, the absorbance values 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 showed clear corrosive effects for both treatment intervals. After three minutes treatment with the test item, the relative absorbance values were reduced to 91.4 %. This value is well above the threshold for corrosion potential (50%). After one hour treatment, relative absorbance values were reduced to 88.7 %. This value, too, is well above the threshold for corrosion potential (15%).

In the guideline, values greater or equal to the threshold are considered as “non-corrosive to skin”. Therefore, the test substance is considered as not corrosive in the Human Skin Model Test.