(E)-1-(2,4,4-trimethyl-2-cyclohexen-1-yl)-2-buten-1-one

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

05 - 11 May 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)

Version / remarks:

adopted: 29 Jul 2016

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: EU B.40 bis (In Vitro Skin Corrosion: Human Skin Model Test)

Version / remarks:

Commission Regulation (EC) No 440/2008 of 30 May 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Hess. Ministerium für Umwelt, Klimaschutz, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany

Test material

Test material information

Constituent 1

Reference substance name:

(E)-1-(2,4,4-trimethyl-2-cyclohexen-1-yl)-2-buten-1-one

EC Number:

254-663-8

EC Name:

(E)-1-(2,4,4-trimethyl-2-cyclohexen-1-yl)-2-buten-1-one

Cas Number:

39872-57-6

Molecular formula:

C13H20O

IUPAC Name:

(E)-1-(2,4,4-trimethyl-2-cyclohexen-1-yl)-2-buten-1-one

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

other: EpiDerm™ (EPI-200)

Source strain:

not specified

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE)
- Model used: EpiDerm™ (EPI-200) (MatTek Corporation, Bratislava, Slovakia)
- Tissue batch number: 25811
- Delivery date: 10 May 2017
- Date of initiation of testing: 10 May 2017

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: room temperature (3 ± 0.5 min exposure), 37 ± 1.5 °C (60 ± 5 min exposure)

REMOVAL OF TEST MATERIAL AND CONTROLS
-Volume and number of washing steps: Tissues were gently rinsed with DPBS (20 times) in order to remove any residual test material.

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 1 mg/mL
- Incubation time: 3 h
- Spectrophotometer: microplate reader (Versamax, Molecular Devices, SoftMax Pro Enterprise v.4.7.1)
- Wavelength: 570 nm
- Filter: without reference filter

FUNCTIONAL MODEL CONDITIONS WITH REFERENCE TO HISTORICAL DATA
- Viability: The quality of the EpiDerm™ tissue was assessed by an MTT cell viability test. The determined OD (540 - 570 nm) was 2.228 ± 0.215 (acceptance criteria: 1.0 - 3.0).
- Barrier function: The barrier function was assessed by determination of the exposure time required to reduce tissue viability by 50% (ET-50) upon application of 100 µL of 1% Triton X-100. The ET-50 value was determined to be 5.16 h (acceptance criteria: 4.77-8.72 h).
- Contamination: The cells used to produce the EpiDerm™ tissue were screened for the presence of viruses, bacteria, yeast and other fungi.

NUMBER OF REPLICATE TISSUES: 2

CONTROL TISSUES USED IN CASE OF MTT DIRECT INTERFERENCE
Since the test substance did not directly reduce the MTT solution, an additional functional check was not performed.

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

PREDICTION MODEL / DECISION CRITERIA
- The test substance is considered to be non-corrosive to skin if the viability after 3 minutes exposure is greater or equal than 50% and the viability after 1 hour exposure is greater or equal than 15%.
- The test substance is considered to be corrosive to skin if the viability after 3 minutes exposure is less than 50%, or if the viability after 3 minutes exposure is greater than or equal to 50% and the viability after 1 hour exposure is less than 15%.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount applied: 50 µL

NEGATIVE CONTROL
- Amount applied: 50 µL

POSITIVE CONTROL
- Amount applied: 50 µL
- Concentration: 8 N

Duration of treatment / exposure:

3 ± 0.5 min and 60 ± 5 min

Number of replicates:

duplicates for each treatment and control group

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

% tissue viability

Remarks:

mean value of 2 tissues

Run / experiment:

3 min exposure

Value:

108.7

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Results 2

Irritation / corrosion parameter:

% tissue viability

Remarks:

mean value of 2 tissues

Run / experiment:

60 min exposure

Value:

119.4

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

OTHER EFFECTS
- Direct-MTT reduction: Since the test substance did not directly reduce MTT, an additional test with freeze-killed or viable tissues was not performed.
- Colour interference with MTT: The test substance did not change colour, when mixed with deionised water and thus passed the colour interference pre-test.

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: The mean OD of the tissue replicates treated with the negative control was ≥ 0.8 and ≤ 2.8 for every exposure time (values between 1.412 and 1.455).
- Acceptance criteria met for positive control: The mean viability of the tissue replicates treated with the positive control for 1 hour was <15% compared to the negative control (4.3%).
- Acceptance criteria met for variability between replicate measurements: The coefficient of variation (CV) in the range 20 – 100% viability between tissue replicates is ≤ 30% (values between 0.4% and 9.8%).

Any other information on results incl. tables

Table 2. Results after treatment with the test substance and controls

	Exposure interval (min)	Aborbance at 570 nm *		Mean absorbance of 2 tissues	SD	Absorbance (% of negative control) **		CV (%)	Rel. absorbance (% of negative control) **
		Tissue 1	Tissue 2			Tissue 1	Tissue 2
Negative control	3	1.399	1.455	1.409	0.014	99.3	100.7	1.0	100.0
Positive control		0.322	0.280	0.301	0.003	22.8	19.9	9.8	21.4
Test substance		1.536	1.528	1.532	0.005	109.0	109.5	0.4	108.7
Negative control	60	1.417	1.377	1.397	0.028	101.4	98.6	2.0	100.0
Positive control		0.066	0.054	0.060	0.008	4.7	3.9	13.4	4.3
Test substance		1.661	1.674	1.667	0.010	118.9	119.9	0.6	119.4

* Mean of three replicate wells after blank correction (blank: 0.035-0.037)

 ** Relative absorbance (rounded values): 100 × (mean absorbance test substance/positive control) / (mean absorbance negative control)

Applicant's summary and conclusion

Interpretation of results:

other: non-corrosive according to OECD 431

Conclusions:

Under the conditions of the conducted test, the test substance did not possess corrosive properties towards reconstructed human epidermis tissue in the EpiDerm™ model, but no prediction on the skin irritation potential can be made and additional testing should be conducted for classification and labeling purposes.