Reaction Mass of (4R)-4-isopropenyl-1-methylcyclohexene and (4R)-4-(2-methoxypropan-2-yl)-1-methylcyclohexene

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

25 October - 04 November 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study was conducted in accordance with international guidelines and in accordance with GLP. All guideline validity criteria were met.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

(R)-p-mentha-1,8-diene

EC Number:

227-813-5

EC Name:

(R)-p-mentha-1,8-diene

Cas Number:

5989-27-5

Molecular formula:

C10H16

IUPAC Name:

(4R)-4-isopropenyl-1-methylcyclohexene

Constituent 2

Reference substance name:

(4R)-4-(2-methoxypropan-2-yl)-1-methylcyclohexene

Cas Number:

30199-25-8

Molecular formula:

C11H20O

IUPAC Name:

(4R)-4-(2-methoxypropan-2-yl)-1-methylcyclohexene

Test material form:

liquid

Specific details on test material used for the study:

RADIOLABELLING INFORMATION (if applicable)
- Radiochemical purity: n/a
- Specific activity: n/a
- Locations of the label: n/a
- Expiration date of radiochemical substance: n/a

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Refrigerated (2 - 8ºC) in the dark and under nitrogen.
- Stability under test conditions: Assumed stable
- Solubility and stability of the test substance in the solvent/vehicle: n/a
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: no

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: no
- Preliminary purification step (if any): n/a
- Final dilution of a dissolved solid, stock liquid or gel: n/a
- Final preparation of a solid: n/a

FORM AS APPLIED IN THE TEST (if different from that of starting material): applied as supplied.

OTHER SPECIFICS: n/a

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

other: reconstructed human epidermis

Cell source:

other: MatTek model kit - source not reported

Justification for test system used:

Guideline specific test system.

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: MatTek
- Tissue batch number(s): 23372
- Production date: not reported
- Shipping date: not reported
- Delivery date: 01 November 2016
- Date of initiation of testing: not reported

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37 ºC
- Temperature of post-treatment incubation (if applicable): 37 ºC

REMOVAL OF TEST MATERIAL AND CONTROLS -Volume and number of washing steps: Rinsing was achieved by filling and emptying each tissue under a constant soft stream of DPBS to gently remove any residual test item. Excess DPBS was removed by blotting the bottom of the tissue insert with tissue paper. Each tissue was placed into the prepared holding plate until all tissues were rinsed.
- Observable damage in the tissue due to washing: No
- Modifications to validated SOP: No

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 1.0 mg/mL
- Incubation time: 3 h
- Spectrophotometer: Anthos 2001 microplate reader
- Wavelength: 562 nm
- Filter: Not reported
- Filter bandwidth: Not reported
- Linear OD range of spectrophotometer: Not reported

FUNCTIONAL MODEL CONDITIONS WITH REFERENCE TO HISTORICAL DATA
- Viability: A comparison of laboratory historical data for negative and positive controls was made to verify the functioning of the test system.
- Barrier function: Not reported
- Morphology: Not reported
- Contamination: Not reported
- Reproducibility: Coefficient of Variation between tissue replicates was ≤ 30%.

NUMBER OF REPLICATE TISSUES: 2

CONTROL TISSUES USED IN CASE OF MTT DIRECT INTERFERENCE
The test item did not reduce MTT.

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

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 50 µL
- Concentration (if solution): unchanged - applied as supplied

VEHICLE
- Amount(s) applied (volume or weight with unit): n/a
- Concentration (if solution): n/a
- Lot/batch no. (if required): n/a
- Purity: n/a

NEGATIVE CONTROL
- Amount(s) applied (volume or weight): 50 µL
- Concentration (if solution): n/a

POSITIVE CONTROL
- Amount(s) applied (volume or weight): 50 µL
- Concentration (if solution): 8.0 N

Duration of treatment / exposure:

3 and 60 mins

Duration of post-treatment incubation (if applicable):

3 h MTT incubation followed by overnight isopropnaol extraction.

Number of replicates:

2 per test group

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

3 minute exposure

Value:

90.3

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Results 2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

60 min exposure

Value:

101.5

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

- OTHER EFFECTS:
- Visible damage on test system: No
- Direct-MTT reduction: No
- Colour interference with MTT: No

DEMONSTRATION OF TECHNICAL PROFICIENCY: Yes

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: The mean OD562 for the negative control treated tissues was 1.836 for the 3-Minute exposureperiod and 1.863 for the 60-Minute exposure period. The negative control acceptance criteria were therefore satisfied.
- Acceptance criteria met for positive control: The relative mean tissue viability for the positive control treated tissues was 2.7% relative to the negative control following the 60-Minute exposure period. The positive control acceptance criterion was therefore satisfied.
- Acceptance criteria met for variability between replicate measurements: In the range 20 to 100% viability the Coefficient of Variation between the two tissue replicates of each treatment group did not exceed 30%. The acceptance criterion was therefore satisfied.
- Range of historical values if different from the ones specified in the test guideline: All values for the positive and negative control were within the historical ranges achieved by the testing facility in the previous twelve months, thus confirming the acceptable functioning of the test system.

Any other information on results incl. tables

Table 1       Relative mean viabilities for each treatment group

Exposure Period	Percentage Viability^*
	Negative Control^§	Positive Control	Test Item
3 minutes	100	5.7	90.3
60 minutes	100	2.7	101.5

^*mean of 2 replicates

^§negative controls set to 100 %

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The test item was considered to be non-corrosive to the skin under the conditions of the test.

Executive summary:

OECD 431 (2017) - The skin corrosivity potential of reaction mass of (4R)-4-isopropenyl-1-methylcyclohexene and (4R)-4-(2-methoxypropan-2-yl)-1-methylcyclohexene was assessed using an EpiDerm Reconstructed Human Epidermis (RHE) Model Kit in accordance with OECD guidance 431 and GLP.

 

Duplicate tissues were treated with the test item for exposure periods of 3 and 60 mins. At the end of the exposure period the test item was rinsed from each tissue before being loaded with MTT. After MTT loading each tissue was placed in 2 mL isopropanol for MTT extraction. After extraction, each tissue was pierced and the extraction solution aliquoted for absorbance measurements. Absorbency at 562 nm of each well was measured using a Anthos 2001 microplate reader.

Mean viability of tissues exposed to the test substance after 3 and 60 minutes were 90.3 and 101.5 %, respectively. The quality criteria required for acceptance of the results was met.

Under the conditions of this study the test substance is not considered to be corrosive to the skin.