Phenol, 4-(9H-carbazol-3-ylamino)-, reaction products with sodium sulfide (Na2(Sx)) and sulfur, leuco deriv.

Endpoint summary

Description of key information

Skin irritation:

Based on the results of an OECD 439 study, the test item is considered not to be irritant to skin.

Eye irritation:

Based on the results of an OECD 437 study, the test item is considered not to have an eye damaging potential.

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:

12 June 2017 - 21 July 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:

2015

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2017

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Justification for test system used:

The EPISKIN model has been validated for irritation testing in an international trial. After a review of scientific reports and peer reviewed publications on the EPISKIN method, it showed evidence of being a reliable and relevant stand-alone test for predicting rabbit skin irritation, when the endpoint is evaluated by MTT reduction and for being used as a replacement for the Draize Skin Irritation test (OECD TG 404 and Method B.4 of Annex V to Directive 67/548/EEC) for the purposes of distinguishing between skin irritating and non-skin irritating test substances (STATEMENT OF VALIDITY OF IN-VITRO TESTS FOR SKIN IRRITATION; ECVAM; Institute for Health & Consumer Protection; Joint Research Centre; European Commission; Ispra; 27 April 2007).

Vehicle:

unchanged (no vehicle)

Details on test system:

EpiSkinTM Small Model (EpiSkinTMSM), manufactured by EPISKIN SNC Lyon, France, is a three-dimensional human epidermis model. Adult human-derived epidermal keratinocytes are seeded on a dermal substitute consisting of a collagen type I matrix coated with type IV collagen. A highly differentiated and stratified epidermis model is obtained after 13-day culture period comprising the main basal, supra basal, spinous and granular layers and a functional stratum corneum (Tinois et al., 1994). Its use for skin irritation testing involves topical application of test materials to the surface of the epidermis, and the subsequent assessment of their effects on cell viability.

Supplier: SKINETHIC Laboratories, 4, rue Alexander Fleming, 69366 Lyon Cedex 07 - France
Batch No.: 17-EKIN-024
Expiry date: 19 June 2017
Units: EpiSkinTMSM plate containing up to 12 reconstructed epidermis units (area: 0.38 cm2) each reconstructed epidermis is attached to the base of a tissue culture vessel with an O-ring set and maintained on nutritive agar for transport.
Plate: 12-well assay plate
Punch: EpiSkinTMSM biopsy punch for easy sampling of epidermis
Medium: sterile “Maintenance Medium” for incubations (Batch No.: 17 MAIN3 024; Exp. Date: 21 June 2017)
sterile “Assay Medium” for use in MTT assays (Batch No.: 17 ESSC 023; Exp. Date: 21 June 2017)
The EpiSkinTMSM units were kept in their packaging at room temperature until the pre-incubation was started. The maintenance and assay medium were stored at 2-8 °C.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

yes, concurrent MTT non-specific colour control

Amount/concentration applied:

10 mg of the test item was applied evenly to the epidermal surface.
10 µL positive control (SDS 5 % aq.) or negative control (1x PBS) was used.

Duration of treatment / exposure:

The plates with the treated epidermis units were incubated for the exposure time of 15 minutes (± 0.5 min) at room temperature.

Duration of post-treatment incubation (if applicable):

42 hours (± 1h) at 37°C in an incubator with 5 % CO2, ≥ 95 % humidified atmosphere.

Number of replicates:

In this assay 3 replicates per test item and 3 replicates negative controls, 3 replicates positive controls, 2 replicates colour controls and 2 replicates non-specific colour control were used. Furthermore, 3 killed treated tissues and 3 killed negative control tissues are used for the MTT evaluation.

Irritation / corrosion parameter:

% tissue viability

Remarks:

relative viability %

Run / experiment:

1

Value:

75

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Irritation / corrosion parameter:

% tissue viability

Remarks:

% relative viability

Run / experiment:

2

Value:

74

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Irritation / corrosion parameter:

% tissue viability

Remarks:

% relative viability

Run / experiment:

3

Value:

85

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Irritation / corrosion parameter:

% tissue viability

Remarks:

% mean relative viability

Run / experiment:

1-3

Value:

78

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:

Positive and negative controls showed the expected cell viability values within acceptable limits. The experiment was considered to be valid.

OD values and viability percentages of the controls:

Substance	Optical Density (OD)		Viability (%)
Negative Control: 1x PBS	1	0.771	107
	2	0.602	84
	3	0.786	109
	mean	0.720	100
	standard deviation (SD)		14.23
Positive Control: SDS (5 % aq.)	1	0.056	8
	2	0.062	9
	3	0.124	17
	mean	0.081	11
	standard deviation (SD)		5.27

 

OD values and viability percentages of the test item (including corrected values):

Test Item	Optical Density (OD)		TODTT	Viability (%)	Relative Viability (%)
	1	0.558	0.542	78	75
	2	0.552	0.536	77	74
	3	0.630	0.614	87	85
	mean	0.580	0.564	81	78
	standard deviation (SD)			6.00	6.00

 

OD values of additional controls for MTT-interacting test item:

Additional controls	Optical Density (OD)
Negative control killed tissues: 1x PBS	1	0.054
	2	0.044
	3	0.066
	mean	0.055
Test item treated killed tissues:	1	0.107
	2	0.059
	3	0.047
	mean	0.071

 

OD values and NSC % of additional control:

Additional colour control	Optical Density (OD)		Non Specific Colour %(NSC %)
Test item (test item treated tissues without MTT incubation)	1	0.031	4.9
	2	0.040
	mean	0.035

Interpretation of results:

GHS criteria not met

Conclusions:

The test item is considered to be non-irritant to skin and is therefore not classified (UN GHS No Category).

Executive summary:

EpiSkinTMSM test with the test item has been performed to predict its irritation potential by measurement of its cytotoxic effect, as reflected in the MTT assay, according to the OECD Test Guideline No. 439. Disks of EPISKIN (three units) were treated with test item and incubated for 15 minutes at room temperature. Exposure of test material was terminated by rinsing with PBS 1x solution. Epidermis units were then incubated at 37°C for 42 hours in an incubator with 5% CO2. The viability of each disk was assessed by incubating the tissues for 3 hours with MTT solution at 37°C in 5% CO2protected from light. The precipitated formazan was then extracted using acidified isopropanol and quantified spectrophotometrically. SDS (5% aq.) and 1×PBS treated (three units / positive and negative control) epidermis were used as positive and negative controls respectively. For each treated tissue viability was expressed as a percentage relative to negative control. The test item has an intrinsic colour (black, copper), therefore two additional test item treated tissues were used for the non-specific OD evaluation. The test item is a possible MTT-reducer, therefore additional controls (test item treated killed tissues and negative control treated killed tissues) were used to detect and correct for test substance interference with the viability measurement. As the test item is a possible MTT-reducer and has an intrinsic colour (black, copper) to avoid a possible double correction for colour interference, a third control for non-specific colour in killed tissues was performed. Two killed treated tissues were used to avoid a possible double correction for colour interference. The test chemical is identified as requiring classification and labelling according to UN GHS (Category 2 or Category 1), if the mean relative viability after 15 minutes exposure and 42 hours post incubation is less or equal (≤) to 50% of the negative control.

In this in vitro skin irritation test using the EPISKIN model, the test item did not show significantly reduced cell viability in comparison to the negative control (mean relative viability: 78 %). All obtained test item viability results were above 50 % when compared to the viability values obtained from the negative control. Positive and negative controls showed the expected cell viability values within acceptable limits. The experiment was considered to be valid. The test item is considered to be non-irritant to skin and is therefore not classified (UN GHS No Category).

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:

30 October 2017 - 05 March 2018

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 Ocular Corrosives and Severe Irritants)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Species:

cattle

Strain:

not specified

Details on test animals or tissues and environmental conditions:

- Source: Schlachthof Aschaffenburg, 63739 Aschaffenburg, Germany
- Age at study initiation: at least 9 month old donor cattle

Vehicle:

physiological saline

Controls:

yes, concurrent vehicle

yes, concurrent positive control

Amount / concentration applied:

The test item was tested as a 20% suspension (w/v) in saline using sonication for 10 minutes. The pH value of the suspension prior to application was 6.91.

Duration of treatment / exposure:

240 minutes

Number of animals or in vitro replicates:

3 corneae per group (test item, negative control, positive control)

Details on study design:

The corneae were distributed as follows:
Groups Number of Corneae
1 Negative Control 3
2 Positive Control 3
3 Test Item 3
The anterior compartment received the test item suspension or the negative or positive controls at a volume of 0.75 mL each on the surface of the corneae, respectively. The corneae were incubated in a horizontal position at 32 ± 1 °C in the water-bath.
The incubation time lasted 240 minutes.
Afterwards, the test item or the control items, respectively, were each rinsed off from the according application sides with saline, and fresh incubation medium was added into the anterior compartment and opacity was measured (t240). The opacity measurement is described in chapter 3.5.
In the second step of the assay, permeability of the cornea was determined.


SCORING SYSTEM:
Opacity measurement
The opacitometer determines changes in the light transmission passing through the corneae, and displays a numerical opacity value. This value was recorded in a table. The opacitometer OP_KiT opacitometer (Electro Design, 63-Riom France) was calibrated as described in the manual and the opacity of each of the corneae was determined by reading each holder placed in the photoreceptor compartment for treated cornea.

For equilibration and prior to application of the test item or controls, the corneae in the holder were incubated in a vertical position for about one hour at 32 ± 1 °C in a water-bath. At the end of the incubation period, the basal opacity was determined (t0). After exposure of the corneae to the test groups, after rinsing and further incubation of the corneae for two hours, the opacity value was determined again (t240).

Permeability Determination
Following to the opacity readings, the permeability was measured as an indication of the integrity of the epithelial cell sheets. After the final opacity measurement was performed, the incubation medium will be removed from the anterior compartment and replaced by 1 mL of a 0.5% (w/v) sodium fluorescein solution in HBSS. Corneae were incubated again in a horizontal position for 90 ± 10 minutes in a water-bath at 32 ± 1 °C. Incubation medium from the posterior compartment were removed, well mixed and transferred into a 96 well plate and the optical density at 490 nm (OD490) was determined with a spectrophotometer (Versamax® Molecular Devices). The absorbance values will be determined using the software SoftMax Pro Enterprise (version 4.7.1).

DATA EVALUATION
Opacity
The change of opacity value of each treated cornea or positive and negative control corneae is calculated by subtracting the initial basal opacity from the post treatment opacity reading (t240 – t0), for each individual cornea.
The average change in opacity of the negative control corneae is calculated and this value is subtracted from the change in opacity of each treated cornea or positive control to obtain a corrected opacity.

Permeability
The corrected OD490 value of each cornea treated with positive control and test item is calculated by subtracting the average negative control cornea value from the original permeability value for each cornea.

IVIS Calculation
The following formula is used to determine the IVIS of the negative control:
IVIS = opacity value + (15 x OD490 value)
The following formula is used to determine the IVIS of the positive control and the test item:
IVIS = (opacity value – opacity value mean negative control) + (15 x corrected OD490 value)
The mean IVIS value of each treated group is calculated from the IVIS values.
Depending on the score obtained, the test item is classified into the following category according to OECD guideline 437:

IVIS: In vitro Irritancy Score (according to OECD 437):

≤ 3 No Category (according to GHS)
> 3; ≤ 55 No prediction can be made
> 55 Serious eye damaging according to CLP/EPA/GHS (Cat 1)


Criteria for Determination of a Valid Test

The test will be acceptable if
• the positive control gives an IVIS that falls within two standard deviations of the current historical mean (updated every three months), and if
• the negative control responses result in opacity and permeability values that are less than the established upper limits for background opacity and permeability values for bovine corneae treated with the respective negative control.

Irritation parameter:

in vitro irritation score

Remarks:

mean

Run / experiment:

1.3

Value:

0.79

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Irritation parameter:

in vitro irritation score

Remarks:

Replicate 1

Run / experiment:

1

Value:

-0.29

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Irritation parameter:

in vitro irritation score

Remarks:

Replicate 2

Run / experiment:

1

Value:

0.89

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Irritation parameter:

in vitro irritation score

Remarks:

Replicate 3

Run / experiment:

1

Value:

1.77

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Results after 240 Minutes Treatment Time

Test Group	Opacity value = Difference (t240-t0) of Opacity		Permeability at 490 nm (OD490)		IVIS	Mean IVIS	Proposed in vitro Irritancy Score	Standard deviation of in vitro score
		Mean		Mean
Negative Control	0	0.33	0.072	0.063	1.08	1.28	No Category	0.56
	1		0.061		1.92
	0		0.056		0.84
Positive Control	121.67*		0.233*		125.16	126.41	Category 1	1.76
	125.67*		0.184*		128.43
	122.67*		0.198*		125.64
Test item	-0.33*		0.003*		-0.29	0.79	No Category	1.03
	0.67*		0.015*		0.89
	1.67*		0.007*		1.77

*corrected values

Interpretation of results:

GHS criteria not met

Conclusions:

In conclusion, according to the current study and under the experimental conditions reported, thet test item is not categorised as an eye irritant (GHS).

Executive summary:

This in vitro study according to OECD guideline 437 was performed to assess the corneal damage potential of the test item by means of the BCOP assay using fresh bovine corneas. After a first opacity measurement of the fresh bovine corneas (t0), the 20% (w/v) suspension in saline of the test item, the positive, and the negative controls were applied to the different corneas and incubated for 240 minutes at 32± 1 °C. After the incubation phase, the test item as well as the positive and the negative controls were each rinsed from the corneas and opacity was measured again (t240). After the opacity measurements, permeability of the corneas was determined by measuring spectrophotometrically the transfer of sodium fluorescein after incubation in a horizontal position for 90 minutes at 32 ± 1 °C.

For the negative control (saline) neither an increase of opacity nor permeability of the corneas could be observed (mean IVIS = 1.28). The positive control (10% (w/v) benzalkonium chloride in saline) showed clear opacity and distinctive permeability of the corneas (mean IVIS =126.41) corresponding to a classification as serious eye damaging (CLP/EPA/GHS (Cat 1)). The IVIS of the positive control fell within two standard deviations of the HCD. The negative control responses resulted in opacity and permeability values that are less than the established upper limits for background opacity and permeability values for bovine corneas treated with the respective negative control. Therefore the acceptability criteria were fulfilled. The test item was tested as suspension. Relative to the negative control, the test item did not cause an increase of the corneal opacity or permeability. The calculated mean IVIS was 0.79 (threshold for serious eye damage: IVIS > 55). According to OECD 437, the test item is not categorized as an eye irritant (GHS).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin irritation:

EpiSkinTMSM test with the test item has been performed to predict its irritation potential by measurement of its cytotoxic effect, as reflected in the MTT assay, according to the OECD Test Guideline No. 439. Disks of EPISKIN (three units) were treated with test item and incubated for 15 minutes at room temperature. Exposure of test material was terminated by rinsing with PBS 1x solution. Epidermis units were then incubated at 37°C for 42 hours in an incubator with 5% CO2. The viability of each disk was assessed by incubating the tissues for 3 hours with MTT solution at 37°C in 5% CO2protected from light. The precipitated formazan was then extracted using acidified isopropanol and quantified spectrophotometrically. SDS (5% aq.) and 1×PBS treated (three units / positive and negative control) epidermis were used as positive and negative controls respectively. For each treated tissue viability was expressed as a percentage relative to negative control. The test item has an intrinsic colour (black, copper), therefore two additional test item treated tissues were used for the non-specific OD evaluation. The test item is a possible MTT-reducer, therefore additional controls (test item treated killed tissues and negative control treated killed tissues) were used to detect and correct for test substance interference with the viability measurement. As the test item is a possible MTT-reducer and has an intrinsic colour (black, copper) to avoid a possible double correction for colour interference, a third control for non-specific colour in killed tissues was performed. Two killed treated tissues were used to avoid a possible double correction for colour interference. The test chemical is identified as requiring classification and labelling according to UN GHS (Category 2 or Category 1), if the mean relative viability after 15 minutes exposure and 42 hours post incubation is less or equal (≤) to 50% of the negative control.

In this in vitro skin irritation test using the EPISKIN model, the test item did not show significantly reduced cell viability in comparison to the negative control (mean relative viability: 78 %). All obtained test item viability results were above 50 % when compared to the viability values obtained from the negative control. Positive and negative controls showed the expected cell viability values within acceptable limits. The experiment was considered to be valid. The test item is considered to be non-irritant to skin and is therefore not classified (UN GHS No Category).

Skin irritation:

An in vitro study according to OECD guideline 437 was performed to assess the corneal damage potential of the test item by means of the BCOP assay using fresh bovine corneas. After a first opacity measurement of the fresh bovine corneas (t0), the 20% (w/v) suspension in saline of the test item, the positive, and the negative controls were applied to the different corneas and incubated for 240 minutes at 32± 1 °C. After the incubation phase, the test item as well as the positive and the negative controls were each rinsed from the corneas and opacity was measured again (t240). After the opacity measurements, permeability of the corneas was determined by measuring spectrophotometrically the transfer of sodium fluorescein after incubation in a horizontal position for 90 minutes at 32 ± 1 °C.

For the negative control (saline) neither an increase of opacity nor permeability of the corneas could be observed (mean IVIS = 1.28). The positive control (10% (w/v) benzalkonium chloride in saline) showed clear opacity and distinctive permeability of the corneas (mean IVIS =126.41) corresponding to a classification as serious eye damaging (CLP/EPA/GHS (Cat 1)). The IVIS of the positive control fell within two standard deviations of the HCD. The negative control responses resulted in opacity and permeability values that are less than the established upper limits for background opacity and permeability values for bovine corneas treated with the respective negative control. Therefore the acceptability criteria were fulfilled. The test item was tested as suspension. Relative to the negative control, the test item did not cause an increase of the corneal opacity or permeability. The calculated mean IVIS was 0.79 (threshold for serious eye damage: IVIS > 55). According to OECD 437, the test item is not categorized as an eye irritant (GHS).

Justification for classification or non-classification

Classification, Labeling, and Packaging Regulation (EC) No 1272/2008

The available experimental test data are reliable and suitable for classification purposes under Regulation 1272/2008. Based on this data, the substance is not considered to be classified for skin or eye irritation under Regulation (EC) No 1272/2008, as amended for the twelfth time in Regulation (EC) No 2019/521.