Reaction mass of (1S*, 2R*, 5S*)-2-Isopropenyl-5-methylcyclohexanol and (1S*, 2S*, 5R*)-2-Isopropenyl-5-methylcyclohexanol

Endpoint summary

Description of key information

Skin irritation/ corrosion (OECD 439 and OECD 431): irritating

Eye irritation (OECD 437): not irritating

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

27 Sep - 04 Nov 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted 28 July 2015

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Commission Regulation (EC) No 440/2008, 1st
ATP of 23 July 2009

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

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

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

other: EpiDerm™

Source strain:

not specified

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EpiDerm™ (MatTek Corporation, Bratislava, Slovakia)
- Tissue batch number: 23372
- Delivery date: 01 Nov 2016
- Date of initiation of testing: 01 Nov 2016

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37 ± 1.5 °C for 35 min in the incubator; thereafter at room temperature for 25 min in a sterile bench
- Temperature of post-treatment incubation: 37 ± 1.5 °C for 42 h

REMOVAL OF TEST MATERIAL AND CONTROLS
-Volume and number of washing steps: Tissues were gently rinsed with DPBS at least 15 times in order to remove any residual test material. After the rinsing the inserts were submerged in DPBS at least three times. Afterwards the inserts were once again rinsed with sterile DPBS from the inside and the outside.

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, version 4.7.1)
- Wavelength: 570 nm

FUNCTIONAL MODEL CONDITIONS WITH REFERENCE TO HISTORICAL DATA
- Viability: The quality of the EpiDerm™ tissue was assessed by undertaking an MTT cell viability test. The determined OD (540 - 570 nm) was 1.587 ± 0.089 (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 6.25 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: 3

CONTROL TISSUES USED IN CASE OF MTT DIRECT INTERFERENCE: Since the test substance did not directly reduce MTT, an additional test with freeze-killed tissues 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 irritant to skin if the viability after 1 hour exposure is less than 50%.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount applied: 30 µL

NEGATIVE CONTROL
- Amount applied: 30 µL

POSITIVE CONTROL
- Amount applied: 30 µL
-Concentration: 5%

Duration of treatment / exposure:

60 min

Duration of post-treatment incubation (if applicable):

approx. 42 h

Number of replicates:

triplicates for each treatment and control group

Irritation / corrosion parameter:

% tissue viability

Remarks:

mean value of 3 tissues

Run / experiment:

60 min exposure

Value:

2.5

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

OTHER EFFECTS:
- Direct-MTT reduction: The test substance was not considered to be a MTT reducer.
- Colour interference with MTT: The test substance did not change colour when mixed with deionised water. Also its intrinsic colour was not intensive.

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: The negative control OD (1.978, 2.115, 1.902) was in the range of the required acceptability criterion of mean OD ≥ 0.8 and ≤ 2.8 for the 60 min treatment interval thus showing the quality of the tissues.
- Acceptance criteria met for positive control: Exposure to the positive control induced a decrease in the relative absorbance as compared to the negative control to 3.1% thus confirming the validity of the test system.
- Acceptance criteria met for variability between replicate measurements: The relative standard deviations of the 3 identical replicates of the test substance and negative control in the main test were below 10% (threshold of OECD 439: <18%).

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

	Absorbance at 570 nm *			Mean absorbance of 3 wells blank corrected	Rel. absorbance (%) **			Rel. SD (%)	Rel. absorbance (% of negative control)***
	Tissue 1	Tissue 2	Tissue 3		Tissue 1	Tissue 2	Tissue 3
Negative control	1.978	2.115	1.902	1.998	99.0	105.8	95.2	5.4	100.0
Positive control	0.064	0.062	0.057	0.061	3.2	3.1	2.9	5.8	3.1
Test substance	0.051	0.054	0.044	0.050	2.5	2.7	2.2	10.0	2.5

* Mean of 3 replicate wells after blank correction (mean blank value: 0.038)

** Relative absorbance per tissue (rounded values): 100 × (absorbance tissue) / (mean absorbance negative control)

*** Relative absorbance per treatment group (rounded values): 100 × (mean absorbance test item/positive control) / (mean absorbance negative control)

Interpretation of results:

other: irritating potential (Skin Irrit. 2 or Skin Corr. 1 according to Regulation (EC) No 1272/2008)

Conclusions:

Under the conditions of the conducted test, the test substance possessed irritating properties towards reconstructed human epidermis tissue in the EpiDerm™ model.

Executive summary:

The skin irritation potential of the test substance was assesed by an in vitro skin irritation test using a reconstructed human skin model according to OECD Guideline 439 and in compliance with GLP (2017). After treatment with the test substance for 60 min the tissue viability decreased to 2.5% compared to the negative control (threshold for irritancy ≤ 50%). Therefore, the test substance is considered to possess an irritant potential towards human-derived epidermal keratinocytes.

Reference 2

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 Jan - 2 Feb 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted 29 July 2016

Deviations:

no

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 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) TISSUE
- Model used: EpiDerm™ (MatTek Corporation, Bratislava, Slovakia)
- Tissue batch number: 23390
- Delivery date: 31 Jan 2017
- Date of initiation of testing: 31 Jan 2017

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

REMOVAL OF TEST MATERIAL AND CONTROLS
-Volume and number of washing steps: Tissues were gently rinsed using a wash bottle containing DPBS to remove any residual test material (20 times).

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 undertaking an MTT cell viability test.
- 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 6.79 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 MTT, an additional test with freeze-killed or viable tissues was not performed.

PREDICTION MODEL / DECISION CRITERIA
- 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 or equal than 50% and the viability after 1 hour exposure is greater or equal 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:

in duplicates for each treatment and control group

Irritation / corrosion parameter:

% tissue viability

Remarks:

mean value of 2 tissues

Run / experiment:

3 min exposure

Value:

99.1

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Irritation / corrosion parameter:

% tissue viability

Remarks:

mean value of 2 tissues

Run / experiment:

60 min exposure

Value:

46.2

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 negative control OD, both for the 3 and 60 min exposure period, was in the range of ≥ 0.8 and ≤ 2.8 for every exposure time (range: 1.638 to 1.668).
- Acceptance criteria met for positive control: Exposure to the positive control induced a decrease in the relative absorbance < 15% as compared to the negative control, both for the 3 min exposure period (29.4%) and for the 60 min exposure period (8.7%) thus confirming the validity of the test system and the specific batch of tissue models.
- Acceptance criteria met for variability between replicate measurements: The coefficient of variation in the range 20 - 100% viability between tissue replicates was < 30% (range: 0.8 - 11%).

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

	Exposure interval (min)	Mean absorbance of 3 wells		Absorbance at 570 nm *		Mean absorbance of 2 tissues	CV (%)	Mean Rel. absorbance (% of negative control) **
		Tissue 1	Tissue 2	Tissue 1	Tissue 2
Negative control	3	1.655	1.638	1.615	1.597	1.606	0.8	100.0
Positive control		0.483	0.544	0.442	0.503	0.473	9.2	29.4
Test substance		1.756	1.508	1.716	1.467	1.592	11.0	99.1
Negative control	60	1.668	1.644	1.633	1.610	1.622	1.0	100.0
Positive control		0.160	0.189	0.126	0.155	0.140	14.5	8.7
Test substance		0.828	0.740	0.794	0.705	0.750	8.3	46.2

* Mean of three replicate wells after blank correction

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

Interpretation of results:

other: non-corrosive according to Regulation (EC) No 1272/2008

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.

Executive summary:

The skin corrosion potential of the test substance was assessed by an in vitro skin corrosion test using a human skin model according to OECD Guideline 431 and in compliance with GLP (2017). After treatment with the test substance the mean relative absorbance values were 99.1% (3 min exposure) and 46.2% (1 h exposure) and did not exceed threshold for corrosivity (50% after 3 min and 15% after 1h) compared to the negative control. Therefore, the test substance is not considered to be corrosive to the skin.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

04 - 21 Oct 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)

Version / remarks:

adopted Jul 2013

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU method B.47 (Bovine corneal opacity and permeability test method for identifying ocular corrosives and severe irritants)

Version / remarks:

Commission directive (EC) No 1152/2010/EC

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

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

Species:

cattle

Strain:

not specified

Details on test animals or tissues and environmental conditions:

SOURCE OF COLLECTED EYES
- Source: Schlachthof Aschaffenburg, Aschaffenburg, Germany
- Characteristics of donor animals: at least 9 month old
- Storage, temperature and transport conditions of ocular tissue: The isolated eyes were transported in Hank's Buffered Salt Solution (HBSS) at ambient temperature.
- Time interval prior to initiating testing: The corneae were isolated on the same day after delivery of the eyes and directly used in the BCOP test.
- Indication of any existing defects or lesions in ocular tissue samples: All eyes were carefully examined macroscopically for defects. Those presenting defects such as vascularization, pigmentation, opacity and scratches were discarded.

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

TEST MATERIAL
- Applied volume: 0.75 mL

POSITIVE SUBSTANCE
- Applied volume: 0.75 mL
- Purity: 99%

NEGATIVE CONTROL
- Applied volume: 0.75 mL

Duration of treatment / exposure:

10 min at 32 ± 1 °C

Duration of post- treatment incubation (in vitro):

2 h

Number of animals or in vitro replicates:

triplicates for each treatment and control groups

Details on study design:

SELECTION AND PREPARATION OF CORNEAS:
The cornea was carefully removed from the eye using scalpel and rounded scissors. A rim of about 2 mm of tissue (sclera) was left for stability and handling of the isolated cornea. Each cornea was mounted in a specially designed cornea holder.

QUALITY CHECK OF THE ISOLATED CORNEAS:
At the end of the equilibration period, the basal opacity was determined (t0). Each cornea with a value of a basal opacity >7 was discarded.

NUMBER OF REPLICATES: 3 corneae per test group
The test was performed twice, but two replicates of the positive control in the 1st experiment did not meet the acceptance criteria of an IVIS > 55. Therefore, only the results of the 2nd experiment are reported, but the raw data of both experiments are archived.

TREATMENT METHOD:
The cornea holder consists of anterior and posterior compartments, which interface with the epithelial and endothelial sides of the cornea, respectively. The endothelial side of the cornea was positioned against the sealing ring (O-ring) of the posterior part of the holder. The cornea was gently flattened over the O-ring but stretching was avoided. The anterior part of the holder was positioned on the top of the cornea and fixed in place with screws. Both compartments of the holder were filled with incubation medium. The posterior compartment was filled first to return the cornea to its natural convex position. After equilibration for about 1 hour, the anterior compartment received the test substance or the controls on the surface of the corneae. The corneae were incubated in a horizontal position at 32 ± 1 °C in the water-bath for 10 minutes.

REMOVAL OF TEST SUBSTANCE:
The test substance was rinsed off from the application side with saline.
- POST-EXPOSURE INCUBATION: 2 h in a vertical position

METHODS FOR MEASURED ENDPOINTS:
- Corneal opacity: Corneal opacity was determined by the amount of light transmission through the cornea via an opacitometer (OP_KiT opacitometer, Electro Design, France).
- Corneal permeability: The passage of sodium fluorescein dye was measured with the aid of a microplate reader (Versamax Molecular Devices) at 490 nm (OD490).

SCORING SYSTEM: In Vitro Irritancy Score (IVIS), IVIS = opacity value + (15 x OD490 value)

DECISION CRITERIA:
Test substance with an IVIS > 55 was regarded as serious eye damage and labelled Category 1 according to CLP/EPS/GHS.
Test substance with an IVIS ≤ 3 was regarded as non-irritant and labelled in no category.
Test substance with an IVIS > 3; ≤ 55: no prediction can be made.

Irritation parameter:

in vitro irritation score

Remarks:

(mean value of 3 corneae)

Run / experiment:

10 min

Value:

2.72

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

With the negative control (saline) neither an increase of opacity nor permeability of the corneae could be observed (mean IVIS = 1.03).
The positive control (2-ethoxyethanol) was tested undiluted and showed clear opacity and distinctive permeability of the corneae (mean IVIS = 101.18) corresponding to a classification as serious eye damaging.
Relative to the negative control, the test substance did not cause an increase of the corneal opacity or permeability (mean IVIS = 2.72).

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: The negative control resulted in opacity and permeability values that were less than the established upper limits for background opacity and permeability values for bovine corneae treated with the respective negative control.
- Acceptance criteria met for postive control: The positive control resulted in an IVIS which was within two standard deviations of the current historical mean.

Table 2. Results after 10 min incubation period.

Test group	Opacity value = Difference (t130-t0) of Opacity		Permeability at 490 nm (OD490)		IVIS	Mean IVIS
		Mean		Mean
Negative Control	0	0.00	0.086	0.069	1.29	1.03
	0		0.055		0.83
	0		0.065		0.98
Positive Control	83.0*		1.132*		99.99	101.18
	92.0*		1.084*		108.27
	82.0*		0.885*		95.28
Test substance	1.00*		0.110*		2.66	2.72
	1.00*		0.065*		1.98
	3.00*		0.034*		3.52

*: corrected values

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No 1272/2008

Conclusions:

Under the conditions of the BCOP assay the test substance was not irritating to the eye. Application of the test substance to bovine corneae resulted in a calculated mean IVIS of 2.72.

Executive summary:

The eye irritation potential of the test substance was determined by a bovine corneal opacity and permeability (BCOP) test according to OECD Guideline 437 and in compliance with GLP (2017). Application of the test substance to bovine corneae resulted in a calculated mean IVIS of 2.72. Thus, the test substance is not considered to be irritant to the eye.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin

The skin irritation potential of the test substance was assesed by an in vitro skin irritation test using a reconstructed human skin model according to OECD Guideline 439 and in compliance with GLP (2017). After treatment with the test substance for 60 min the tissue viability decreased to 2.5% compared to the negative control (threshold for irritancy ≤ 50%). Therefore, the test substance is considered to possess an irritant potential towards human-derived epidermal keratinocytes.

In a next step, the skin corrosion potential of the test substance was assessed by an in vitro skin corrosion test using a human skin model according to OECD Guideline 431 and in compliance with GLP (2017). After treatment with the test substance the mean relative absorbance values were 99.1% (3 min exposure) and 46.2% (1 h exposure) and did not exceed threshold for corrosivity (50% after 3 min and 15% after 1h) compared to the negative control. Therefore, the test substance is not considered to be corrosive to the skin.

In conclusion, based on these studies the test substance is considered to be irritant to the skin.

Eye

The eye irritation potential of the test substance was determined by a bovine corneal opacity and permeability (BCOP) test according to OECD Guideline 437 and in compliance with GLP (2017). Application of the test substance to bovine corneae resulted in a calculated mean IVIS of 2.72. Thus, the test substance is not considered to be irritant to the eye.

Justification for classification or non-classification

The available data on skin irritation meet the criteria for classification as Skin Irrit. Cat. 2 (H315) according to Regulation (EC) 1272/2008.

The available data on eye irritation do not meet the criteria for classification according to Regulation (EC) 1272/2008, and are therefore conclusive but not sufficient for classification.