4-(cyclohex-1-en-1-yl)-3-methylbutan-1-ol

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

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 guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

4-(cyclohex-1-en-1-yl)-3-methylbutan-1-ol

EC Number:

806-826-5

Cas Number:

1359994-45-8

Molecular formula:

C11H20O

IUPAC Name:

4-(cyclohex-1-en-1-yl)-3-methylbutan-1-ol

Test material form:

liquid

Specific details on test material used for the study:

- Test substance storage In refrigerator (2-8°C) in the dark
- Description: Clear colourless liquid
- Expiry date: 19 March 2015

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Justification for test system used:

In the interest of sound science and animal welfare, a sequential testing strategy is recommended to minimise the need of in vivo testing. One of the validated in vitro skin irritation tests is the EPISKIN test, which is recommended in international guidelines (e.g. OECD and EC).

Vehicle:

unchanged (no vehicle)

Details on test system:

Test system
- EPISKIN Small ModelTM (EPISKIN-SMTM, 0.38 cm2, Batch no.: 14-EKIN-018). This model is a three-dimensional human epidermis model, which consists of adult human-derived epidermal keratinocytes which have been seeded on a dermal substitute consisting of a collagen type I matrix coated with type IV collagen. The keratinocytes were cultured for 13 days, which results in a highly differentiated and stratified epidermis model comprising the main basal, supra basal, spinous and granular layers and a functional stratum corneum.

Preparation and preincubation:
- Tissues: On the day of receipt the tissues were transferred to 12-well plates and preincubated with prewarmed Maintenance Medium for 26 hours at 37°C. Maintenance medium and Assay medium were supplied by Skinethic Laboratories, Lyon, France.
- MTT medium: MTT concentrate (Sigma Aldrich, Zwijndrecht, The Netherlands; 3 mg/ml in PBS) diluted (10x) in Assay medium (final concentration 0.3 mg/ml).
- Environmental conditions: All incubations, with the exception of the test substance incubation of 15 minutes at room temperature, were carried out in a controlled environment, in which optimal conditions were a humid atmosphere of 80 - 100% (actual range 72 - 89%), containing 5.0 ± 0.5% CO2 in air in the dark at 37.0 ± 1.0°C (actual range 36.0 - 36.9°C). Temperature and humidity were continuously monitored throughout the experiment. The CO2 percentage was monitored once on each working day. Temporary deviations from humidity occurred that were caused by opening and closing of the incubator door. Based on laboratory historical data these deviations are considered not to affect the study integrity.

Study design
- Test for reduction of MTT by the test substance: The test substance was checked for possible direct MTT reduction before the study was started. To assess the ability of the test substance to reduce MTT, 25 μl of the test substance was added to 2 ml MTT solution (0.3 mg/ml in PBS). The mixture was incubated for 3 hours at 37°C. A negative control, sterile Milli-Q water was tested concurrently.
- Application/Treatment of the test substance: The test was performed on a total of 3 tissues per test substance together with negative and positive controls. Twenty five μl of the undiluted test substance was added (with a pipette) into 12-well plates on top of the skin tissues. Three tissues were treated with 25 μl PBS (negative control) and 3 tissues with 25 μl 5% SDS (positive control) respectively. The positive control was re-spread after 7 minutes contact time. After the exposure period of 15 minutes at room temperature, the tissues were washed with phosphate buffered saline to remove residual test substance. After rinsing the cell culture inserts were each dried carefully and moved to a new well on 2 ml pre-warmed maintenance medium until all tissues were dosed and rinsed. Subsequently the skin tissues were incubated for 42 hours at 37°C.
- Cell viability measurement: After incubation, cell culture inserts were dried carefully to remove excess medium and were transferred into a 12-wells plate prefilled with 2 ml MTT-medium (0.3 mg/ml). The tissues were incubated for 3 h at 37°C. After incubation the tissues were placed on blotting paper to dry the tissues. Total biopsy was made by using a biopsy punch. Epidermis was separated from the collagen matrix and both parts were placed in prelabeled microtubes and extracted with 500 μl isopropanol (Merck, Darmstadt, Germany). Tubes were stored refrigerated and protected from light for 70 hours. The amount of extracted formazan was determined spectrophotometrically at 570 nm in duplicate with the TECAN Infinite® M200 Pro Plate Reader. Cell viability was calculated for each tissue as a percentage of the mean of the negative control tissues. Skin irritation potential of the test substance was classified according to remaining cell viability following exposure of the test substance.

Interpretation
- Acceptability of the assay: The in vitro skin irritation test is considered acceptable if it meets the following criteria: a) The absolute mean OD570 (optical density at 570 nm) of the three tissues of the negative control should reasonably be within the laboratory historical control data range and the Standard Deviation value (SD) of the % viability should be ≤18. b) The mean relative tissue viability of the positive control should be ≤40% relative to the negative control and the Standard Deviation value (SD) of the % viability should be ≤18. c) The SD calculated from individual % tissue viabilities of the three identically treated replicates should be ≤18.
- Data evaluation and statistical procedures: A test substance is considered irritant in the skin irritation test if: The relative mean tissue viability of three individual tissues after 15 minutes of exposure to the test substance and 42 hours of post incubation is ≤ 50% of the mean viability of the negative controls. A test substance is considered non-irritant in the in vitro skin irritation test if: The relative mean tissue viability of three individual tissues after 15 minutes of exposure to the test substance and 42 hours of post incubation is > 50% of the mean viability of the negative controls.

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Value:

9

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Applicant's summary and conclusion

Interpretation of results:

Category 2 (irritant) based on GHS criteria