Reaction product of o-cresol and camphene, obtained by addition, hydrogenation and distillation

Endpoint summary

Description of key information

Skin irritation/corrosion (OECD 439): not irritating

Eye irritation (OECD 437): not irritating

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 Jun - 04 Aug 2017

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 Jul 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) 440/2008, 1st ATP 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: 25834
- Delivery date: 01 Aug 2017
- Date of initiation of testing: 01 Aug 2017

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

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 3 times. Afterwards the inserts were once again rinsed with 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 v.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 1.866 ± 0.143 (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 6.02 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 or equal 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% aqueous solultion

Duration of treatment / exposure:

60 min

Duration of post-treatment incubation (if applicable):

approximately 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

Value:

75.2

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 (1.436, 1.405 and 1.404) 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 4.2% 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 4.9% (threshold of OECD 439: <18%).

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

	Mean absorbance at 570 nm *			Mean absorbance of 3 tissues 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	1.436	1.405	1.404	1.415	101.5	99.3	99.2	1.3	100.0
Positive control	0.056	0.061	0.060	0.059	3.9	4.3	4.3	4.9	4.2
Test substance	1.033	1.097	1.062	1.064	73.0	77.5	75.0	3.0	75.2

* Mean of 3 replicate wells after blank correction (blank values: well 1 and 2: 0.038; well 3: 0.037)

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

Conclusions:

Under the conditions of the conducted test, the test substance did not possess irritating properties towards reconstructed human epidermis tissue in the EpiDerm™ model.

Executive summary:

Under the conditions of the conducted test, the test substance did not possess irritating properties towards reconstructed human epidermis tissue in the EpiDerm™ model. The tissue viablilty was 75.2%.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not 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:

19 Jun 2017

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:

Apr 1997

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 Regulation (EU) No 1152/2010

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: AB Schlachthof GmbH & Co. KG, Aschaffenburg, Germany
- 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) containing 1% (v/v) penicillin/streptomycin (100 units/mL penicillin and 100 μg/mL streptomycin) in the cooled slaughter-house until transportation on the same morning to the laboratory using a Styrofoam box.
- Time interval prior to initiating testing: The corneae were isolated on the same day after delivery of the eyes. The cornea were directly used in the BCOP test on the same day.
- 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
- Amount applied: 0.75 mL

POSITIVE CONTROL
- Amount applied: 0.75 mL
- Purity: 99%

NEGATIVE CONTROL
- Amount applied: 0.75 mL
- Concentration: 0.9% NaCl (w/v) in deionised water

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 group

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.

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 in a vertical position, 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 followed by a second opacity reading (t130)

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 after incubation for 90 minutes 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 + (15x 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 cornea

Run / experiment:

10 min

Value:

0.57

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 = 0.74).
The positive control (2-ethoxyethanol) was tested undiluted and showed clear opacity and distinctive permeability of the corneae (mean IVIS = 83.64) corresponding to a classification as serious eye damaging. Relative to the negative control, the test substance did not cause a relevant increase of the corneal opacity or permeability (mean IVIS = 0.57).

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 positive control: The positive control resulted in an IVIS which was within two standard deviations of the current historical mean.

Table 1. Results after 10 min incubation time

Test group	Opacity value = Difference (t130-t0) of Opacity		Permeability at 490 nm (OD490)		IVIS	Mean IVIS
		Mean		Mean
Negative Control	0	0.00	0.050	0.049	0.75	0.74
	0		0.050		0.75
	0		0.048		0.72
Positive Control	61.0*		1.276*		80.14	83.64
	64.0*		0.483*		86.24
	67.0*		1.169*		84.53
Test substance	1.00*		0.010*		0.15*	0.57
	0.00*		0.012*		0.18*
	0.00*		0.026*		0.39*

* Corrected values

Interpretation of results:

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

Conclusions:

Under conditions of the Bovine Corneal Opacity and Permeability Test (BCOP) the test subtance was not irritating to the eye. Application of the test substance to bovine corneae resulted in a calculated mean IVIS of 0.57.

Executive summary:

Under conditions of the Bovine Corneal Opacity and Permeability Test (BCOP) the test subtance was not irritating to the eye. Application of the test substance to bovine corneae resulted in a calculated mean IVIS of 0.57.

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 determined 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 was 75.2% (threshold for irritancy ≤ 50%).Therefore, the test substance is not considered to possess an irritant potential towards human-derived epidermal keratinocytes.

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 0.57. Thus, the test substance is not considered to be irritating to the eye.

Justification for classification or non-classification

The available data on skin and eye irritation do not meet the criteria for classification according to Regulation (EC) No. 1272/2008, and are therefore conclusive but not sufficient for classification.