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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:
weight of evidence
Study period:
2014-06-20 to 2014-06-18
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2014
Report date:
2014

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)
Version / remarks:
26 July 2013
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)
Version / remarks:
06 July 2012
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: EpiSkin™ SOP, Version 1.8 (February 2009), ECVAM Skin Irritation Validation Study: Validation of the EpiSkin™ test method 15 min - 42 hours for the prediction of acute skin irritation of chemicals.
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
3-[(3-{[(3-acetoxy-2,2-dimethylpropylidene)amino]methyl}-3,5,5-trimethylcyclohexyl)imino]-2,2-dimethylpropyl acetate
EC Number:
805-722-7
Cas Number:
1064082-81-0
Molecular formula:
C24H42N2O4
IUPAC Name:
3-[(3-{[(3-acetoxy-2,2-dimethylpropylidene)amino]methyl}-3,5,5-trimethylcyclohexyl)imino]-2,2-dimethylpropyl acetate
Test material form:
liquid

In vitro test system

Test system:
human skin model
Source species:
other: reconstructed human epidermis
Cell type:
non-transformed keratinocytes
Justification for test system used:
The EPISKIN model has been validated for irritation testing in an international trial. After a review of scientific reports and peer reviewed publications on the EPISKIN method, it showed evidence of being a reliable and relevant stand-alone test for predicting rabbit skin irritation, when the endpoint is evaluated by MTT reduction and for being used as a replacement for the Draize Skin Irritation test (OECD TG 404 and Method B.4 of Annex V to Directive 67/548/EEC) for the purposes of distinguishing between skin irritating and no skin irritating test substances (STATEMENT OF VALIDITY OF IN-VITRO TESTS FOR SKIN IRRITATION; ECVAM; Institute for Health & Consumer Protection; Joint Research Centre; European Commission; Ispra; 27 April 2007)
Vehicle:
unchanged (no vehicle)
Details on test system:
RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EpiSkinTMSM, EPISKIN SNC Lyon, France
- Tissue batch number: 14-EKIN-022
- Expiry date: 23 June 2014
- Date of initiation of testing: 18 June 2014

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: room temperature
- Temperature of post-treatment incubation: 37 °C

REMOVAL OF TEST MATERIAL AND CONTROLS
-Volume and number of washing steps: After the incubation time, the EPISKINTMSM units were removed and rinsed thoroughly with PBS 1 x solution to remove all of the test material from the epidermal surface. The rest of the PBS was removed from the epidermal surface with a suitable pipette tip linked to a vacuum source (care was taken to avoid damaging to the epidermis).
- Observable damage in the tissue due to washing: None

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 2 mL of 0.3 mg/mL MTT per well
- Incubation time: 3 h
- Spectrophotometer: Thermo Scientific; Multiscan FC
- Wavelength: 570 nm

NUMBER OF REPLICATE TISSUES: 3

CONTROL TISSUES USED IN CASE OF MTT DIRECT INTERFERENCE
According to the result of the In Vitro Skin Corrosion Test in the EPISKIN Model, the test item showed no direct interaction with MTT. Using of additional control was not necessary.

NUMBER OF INDEPENDENT TEST SEQUENCES / EXPERIMENTS TO DERIVE FINAL PREDICTION: 1

PREDICTION MODEL / DECISION CRITERIA
- The test substance is considered to be irritant to skin if the viability after 15 minutes exposure and 42 hours post incubation is less than or equal to 50% of the negative control.
- The test substance is considered to be non-irritant to skin if the viability after 15 minutes exposure and 42 hours post incubation is greater than 50% of the negative control.
Control samples:
yes, concurrent negative control
yes, concurrent positive control
Amount/concentration applied:
TEST MATERIAL
- Amount applied: 10 µL

NEGATIVE CONTROL
- Amount applied: 10 µL
- Concentration: 1 x PBS

POSITIVE CONTROL
- Amount applied: 10 µL
- Concentration: 5 % aq. Solution
Duration of treatment / exposure:
15 min
Duration of post-treatment incubation (if applicable):
42 h
Number of replicates:
3

Results and discussion

In vitro

Results
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
Test item
Value:
87
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Other effects / acceptance of results:
- OTHER EFFECTS:
- Visible damage on test system: none
- Direct-MTT reduction: According to the results of the previously performed “In Vitro Skin Corrosion Test with SIKA Hardener AI (SIKA Härter AI) in the EPISKIN Model (Study No.: 644-431-4850), no colour change was observed after three hours of incubation. The test material did not interact with the MTT, therefore additional controls and data calculations were not necessary. A false estimation of viability can be precluded.
- Colour interference with MTT: According to the results of the previously performed “In Vitro Skin Corrosion Test with SIKA Hardener AI (SIKA Härter AI) in the EPISKIN Model (Study No.: 644-431-4850), the test item showed no ability to become coloured in contact with water, therefore additional controls and data calculations were not necessary. A false estimation of viability can be precluded.

DEMONSTRATION OF TECHNICAL PROFICIENCY: Prior to routine use of the method TOXI-COOP ZRT. demonstrated the technical proficiency, using the ten Proficiency Chemicals according to OECD Test Guideline No. 439.

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: The mean OD value of the three negative control tissues was 0.819.
- Acceptance criteria met for positive control: The mean OD value obtained for the positive control was 0.143 and this result corresponds to 18 % viability when compared to the results obtained from the negative controls.
- Acceptance criteria met for variability between replicate measurements: Each calculated standard deviation value (SD) for the % viability was below 18.
All validity criteria were within acceptable limits and therefore the study can be considered as valid.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
The in vitro skin irritation study revealed that the test item is not irritating to the skin.
Executive summary:

In the OECD 439 compliant in vitro skin irritation study, the purpose was to determine the skin irritation potential of the test item on reconstituted human epidermis in the EPISKIN model.

Disks of epidermal units (three units / chemical) were treated with the test item and incubated for 15 minutes at room temperature. Exposure of the test material was terminated by rinsing the epidermal units with PBS 1 x solution. Epidermis units were then incubated at 37 °C for 42 hours in an incubator with 5 % CO2. The viability of each disk was assessed by incubating the tissues for 3 hours with MTT solution at 37 °C in 5 % CO2 and protected from light. The resulting formazan chrystals were extracted with acidified isopropanol and quantified with the optical densities (OD) recorded spectrophotometrically.

SDS 5 % aq. and 1 x PBS treated epidermis units were used as positive and negative controls, respectively. For each treated tissue, viability was expressed as a percentage relative to negative control.

The test item is considered to be a skin irritant, if the mean relative viability after 15 minutes exposure and 42 hours post incubation is less than or equal to (≤) 50 % when compared to the viability values obtained from the negative control.

In this In Vitro Skin Irritation Test using the EPISKIN model, the test item did not show significantly reduced cell viability in comparison to the negative control. All obtained test item viability results were above 50 % when compared to the viability values obtained from the negative control. Therefore the test item was considered to be non-irritant to skin.

Positive and negative controls showed the expected cell viability values within acceptable limits. The experiment was considered to be valid.