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Diss Factsheets

Administrative data

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Bacterial reverse mutation test:

The registered substance, α,α-bis[4-(dimethylamino)phenyl]-4-(phenylamino)naphthalene-1-methanol (CAS Number: 6786-83-0) tested non-mutagenic (negative) in Salmonella typhimurium tester strains TA1537, TA1535, TA98, TA100 and TA102 with and without S9 metabolic activation system. The test was performed according to OECD TG 471 and in compliance with OECD Principles of Good Laboratory Practice.

In vitro mammalian chromosomal aberration test:

The registered substance, (4-anilino-1-naphthyl){bis[4-(dimethylamino)phenyl]}methanol (CAS No. 6786-83-0) was tested non-clastogenic (negative) in mammalian cells up to the concentration of 0.00625 mg/ml either in the presence or absence of S9 metabolic activation system in CHO cells. The test was performed according to OECD TG 473 and in compliance with GLP.

In vitro gene mutation test in mammalian cells:

The registered substance, α,α-bis[4-(dimethylamino)phenyl]-4-(phenylamino)naphthalene-1-methanol [CAS No.: 6786-83-0] was tested non-mutagenic (negative) in mammalian cells up to 0.015 mg/mll both in the presence and absence of S9 metabolic activation. The test was performed according to OECD TG 476 and in compliance with GLP.

Link to relevant study records

Referenceopen allclose all

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
The study contains experimental data of the registered substance.
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
Adopted: 21st July 1997, Corrected: 26th June2020
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay
Specific details on test material used for the study:
- Name of test material: (4-anilino-1-naphthyl){bis[4-(dimethylamino)phenyl]methanol
- Molecular formula: C33H33N3O
- SMILES: CN(C)C1=CC=C(C=C1)C(C2=CC=C(C=C2)N(C)C)(C3=CC=C(C4=CC=CC=C43)NC5=CC=CC=C5)O
- Physical state: Solid
- Purity: 99.62%
- Apperance: Blackish powder
- Batch Number: KCP/FS/742/20
- Expiry Date: 21.08.2021
- Storage condition: Room Temperature (20 to 30 C)
Target gene:
Histidine operon
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102
Metabolic activation:
with and without
Metabolic activation system:
S9 mix [Cofactors (Cofactor ingredients: D-glucose-6-phosphate, β-NADP, magnesium chloride, potassium chloride, sodium phosphate and Liver homogenate] was prepared prior to use in the study. The post-mitochondrial fraction (liver homogenate) was used at the concentration of 10 % (v/v) in the S9 mix.
Test concentrations with justification for top dose:
0 (solvent control), 0.0625, 0.125, 0.25, 0.5 and 1 mg/plate.

Justification for the top dose: The highest test concentration was selected based on solubility, precipitation checks, and a preliminary cytotoxicity test. The test substance was soluble in DMSO up to 10 mg/ml, giving the final test concentration of 1 mg/ml. No precipitation that can interfere with scoring was observed at 1 mg/ml. A reduction in revertant counts and moderate inhibition of the background lawn was observed at 1 mg/m. Hence, 1 mg/ml was selected as the highest test dose for the reverse mutation test.
Vehicle / solvent:
dimethyl sulfoxide (DMSO)
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
2-nitrofluorene
sodium azide
benzo(a)pyrene
mitomycin C
Details on test system and experimental conditions:
METHOD OF APPLICATION: Trial1 (plate incorporation) in agar, Trial 2 (preincubation) in medium

DURATION
- Preincubation period: 20 min
- Exposure duration: 48 hours
- Expression time (cells in growth medium): 48 hours

SELECTION AGENT (mutation assays): Top agar was prepared with 0.6 % (w/v) bacto agar and 0.6 % (w/v) sodium chloride and was supplemented with 10 % (v/v) of 0.5 mM histidine/biotin solution for selection of histidine revertants

NUMBER OF REPLICATIONS: Triplicates
Evaluation criteria:
A Test Item is considered as a mutagen if a biologically relevant increase in the mean number of revertants exceeding the threshold of twice (strains TA98, TA100 and TA102) or thrice (strains TA1535 and TA1537) the colony count of the corresponding solvent control is observed. A dose-dependent increase is considered biologically relevant if the threshold is exceeded at more than one concentration. A dose-dependent increase exceeding the threshold at only one concentration is judged as biologically relevant if reproduced in an independent experiment. A dose-dependent increase in the number of revertant colonies below the threshold is regarded as an indication of a mutagenic potential if reproduced in an independent experiment.
Statistics:
The colonies were counted manually. Then, the mean number of revertant colonies and the standard deviation within the plates for each concentration were compared to the spontaneous reversion rates of the control. Microsoft Office Excel-based calculations were used for descriptive statistical analysis.
Key result
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
A decrease in mean revertant counts was observed at 1 mg/ml both with and without S9 mix.
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
True negative controls validity:
not examined
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
A decrease in mean revertant counts was observed at 1 mg/ml both with and without S9 mix.
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
True negative controls validity:
not examined
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
A decrease in mean revertant counts was observed at 1 mg/ml both with and without S9 mix.
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
True negative controls validity:
not examined
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
A decrease in mean revertant counts was observed at 1 mg/ml both with and without S9 mix.
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
True negative controls validity:
not examined
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 102
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
A decrease in mean revertant counts was observed at 1 mg/ml both with and without S9 mix.
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
True negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
For each tester strain, the frequency of the spontaneous revertant colonies in the vehicle control was within the acceptable range of historical data of the lab. In addition, the positive controls used in the study produced significant increases in the mean number of revertant colonies in all of the tester strains when compared to the control data, thus confirming the validity of the test system to detect specific mutagens in the presence and absence of a metabolic activation system.
Remarks on result:
other: No mutagenic potential was observed

TABLES

Table1          Mean Revertant Colony Count – Preliminary Cytotoxicity Assay

Test Item

Concentration

(mg/plate)

TA 98

TA 100

- S9

+ S9

- S9

+ S9

Mean

SD

Mean

SD

Mean

SD

Mean

SD

NC

(Distilled water)

22.00

(NI)

2.00

20.33

(NI)

0.58

101.33

(NI)

3.06

101.00

(NI)

6.24

VC

(Dimethyl sulfoxide)

20.67

(NI)

2.08

21.00

(NI)

2.65

100.67

(NI)

6.11

99.00

(NI)

3.00

T1

(0.0000128)

22.00

(NI)

1.73

21.67

(NI)

1.15

95.67

(NI)

1.53

96.67

(NI)

3.06

T2

(0.000064)

20.00

(NI)

2.00

21.33

(NI)

2.31

100.67

(NI)

2.08

97.33

(NI)

1.53

T3

(0.00032)

20.33

(NI)

2.31

21.67

(NI)

1.15

95.67

(NI)

2.89

94.33

(NI)

1.53

T4

(0.0016)

20.33

(NI)

1.15

22.00

(NI)

2.00

95.00

(NI)

2.65

94.67

(NI)

2.08

T5

(0.008)

21.33

(NI)

1.53

19.67

(NI)

3.06

97.33

(NI)

4.93

93.00

(NI)

3.46

T6

(0.04)

19.67

(NI)

2.52

21.33

(NI)

0.58

95.67

(NI)

3.51

88.00

(NI)

5.29

T7

(0.2)

19.33

(NI)

1.53

18.67

(NI)

0.58

91.00

(NI)

5.00

88.00

(NI)

3.46

T8

(1.0)

15.00

(MI)

1.00

16.67

(MI)

1.15

86.00

(MI)

2.00

82.00

(MI)

1.73

PC

333.67

(NI)

13.58

323.33

(NI)

8.33

684.00

(NI)

5.00

673.67

(NI)

11.24

Key:   NC = Negative Control, VC = Vehicle control, PC = Positive Control, -S9 = Absence of metabolic activation, +S9 = Presence of metabolic activation, SD = Standard Deviation, T1-T8 = Test Item concentration from lower to higher, NI = No inhibition, MI = Moderate inhibition.

 

Positive Controls:

2-Nitrofluorene

:

TA98 (absence of metabolic activation)

Sodium azide

:

TA100 (absence of metabolic activation)

Benzo[a]pyrene

:

TA98 and TA100 (presence of metabolic activation)


Table2          Mean Revertant Colony Count in Trial I(Plate Incorporation Method)

Absence of metabolic activation

Presence of metabolic activation (+S9 10% v/v S9 Mix)

Test Item

Concentration

(mg/plate)

TA 1535

TA 1537

TA 102

TA 98

TA 100

TA 1535

TA 1537

TA 102

TA 98

TA 100

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mean

SD

NC (Distilled water)

12.67

1.53

7.00

1.00

240.00

8.19

20.33

2.52

102.33

4.51

14.33

1.15

5.67

0.58

236.67

6.81

21.67

3.21

94.67

1.15

VC (Dimethyl sulfoxide)

13.00

1.00

5.33

0.58

241.67

4.04

21.00

2.65

97.67

4.73

12.33

0.58

6.33

1.15

233.00

6.24

20.67

2.08

102.67

4.04

T1(0.625)

12.67

1.15

6.67

1.15

237.67

8.62

21.33

2.89

104.33

2.52

12.33

1.15

5.67

0.58

230.67

6.11

20.67

2.31

97.00

5.57

T2 (0.125)

11.67

1.15

6.67

0.58

237.67

7.23

21.67

2.52

99.33

5.51

13.33

2.08

7.33

1.15

236.67

5.69

18.33

1.15

98.67

3.06

T3 (0.25)

13.33

1.15

6.00

2.00

231.67

4.93

19.33

1.15

98.33

4.51

12.67

1.53

6.33

1.15

232.33

7.37

20.67

1.15

96.00

2.65

T4 (0.5)

12.67

2.08

6.33

0.58

229.67

6.66

21.00

2.00

102.67

4.04

13.33

0.58

6.00

2.00

235.33

7.09

18.67

1.15

95.33

2.52

T5 (1.0)

10.33

0.58

5.67

1.15

198.33

12.66

16.67

1.15

82.00

2.00

10.00

1.00

5.00

1.73

193.67

11.93

16.00

1.00

84.67

4.73

PC

329.00

16.09

191.00

4.36

1606.00

27.84

329.00

15.87

682.33

9.71

315.00

12.29

196.00

10.44

1627.67

9.61

323.33

8.33

701.67

14.50

Key:   NC = Negative Control, VC = Vehicle control, PC = Positive Control, -S9 = Absence of metabolic activation, +S9 = Presence of metabolic activation, SD = Standard Deviation, T1-T5 = Test Item concentration from lower to higher.

 

Positive Controls:

2-Nitrofluorene

:

TA98 (absence of metabolic activation)

Sodium azide

:

TA100 and TA1535 (absence of metabolic activation)

9-Aminoacridine

:

TA1537 (absence of metabolic activation)

Mitomycin-C

:

TA102(absence of metabolic activation)

Benzo[a]pyrene

:

TA98, TA100, TA1535, TA1537 and TA102 (presence of metabolic activation)

 

Table3          Mean Revertant Colony Count in Trial II(Preincubation Method)

Absence of metabolic activation

Presence of metabolic activation (+S9 10% v/v S9 Mix)

Test Item

Concentration

(mg/plate)

TA 1535

TA 1537

TA 102

TA 98

TA 100

TA 1535

TA 1537

TA 102

TA 98

TA 100

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mean

SD

NC (Distilled water)

12.33

1.53

7.33

1.15

239.00

7.00

21.7

3.2

99.33

6.81

13.67

0.58

6.33

1.53

233.00

7.00

21.33

1.53

100.67

3.21

VC (Dimethyl sulfoxide)

12.00

1.73

6.33

1.15

239.67

9.45

20.0

2.0

101.33

7.02

12.67

1.15

5.33

0.58

236.67

7.09

21.33

0.58

97.33

2.89

T1(0.625)

12.33

1.53

6.67

1.15

238.00

8.72

20.0

3.0

95.33

2.08

13.33

0.58

6.67

0.58

235.00

10.15

21.67

3.21

91.67

2.65

T2 (0.125)

12.67

2.31

6.00

1.73

233.33

6.51

20.3

2.3

98.33

4.04

13.67

1.53

7.67

0.58

232.67

4.04

20.67

2.08

102.00

3.51

T3 (0.25)

12.67

0.58

5.33

0.58

234.67

2.31

22.0

2.0

94.33

2.52

12.33

1.15

5.67

1.53

236.00

7.00

22.00

1.73

96.00

4.36

T4 (0.5)

14.33

1.53

6.67

1.15

230.00

12.12

19.0

1.0

92.67

3.21

12.67

1.15

5.67

2.08

234.33

7.57

20.00

3.00

95.00

0.58

T5 (1.0)

10.67

1.15

5.00

1.44

194.33

8.50

15.7

1.5

81.67

3.79

9.33

1.15

3.33

1.15

185.67

6.66

14.67

0.58

82.00

3.21

PC

323.33

10.02

204.33

11.68

1590.33

15.63

325.7

10.6

700.67

14.57

313.00

6.56

201.00

13.45

1630.00

18.68

329.67

17.21

713.67

6.51

Key:     NC = Negative Control, VC = Vehicle control, PC = Positive Control, -S9 = Absence of metabolic activation, +S9 = Presence of metabolic activation, SD = Standard Deviation,T1-T5 = Test Item concentration from lower to higher.

 

Positive Controls:

2-Nitrofluorene

:

TA98 (absence of metabolic activation)

Sodium azide

:

TA100 and TA1535 (absence of metabolic activation)

9-Aminoacridine

:

TA1537 (absence of metabolic activation)

Mitomycin-C

:

TA102 (absence of metabolic activation)

Benzo[a]pyrene  

:

TA98, TA100, TA1535, TA1537 and TA102 (presence of metabolic activation)

Table4          Fold Increase

Trial I - Plate Incorporation Method

Trial II – Preincubation Method

Test Item

Concentration

(mg/plate)

TA 98

TA 100

TA 1535

TA 1537

TA 102

TA 98

TA 100

TA 1535

TA 1537

TA 102

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

-S9

+S9

NC (Distilled water)

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

VC (Dimethyl sulfoxide)

1.03

0.95

0.95

1.08

1.03

0.86

0.76

1.12

1.01

0.98

0.92

1.00

1.02

0.97

0.97

0.93

0.86

0.84

1.00

1.02

T1(0.625)

1.02

1.00

1.07

0.94

0.97

1.00

1.25

0.89

0.98

0.99

1.00

1.02

0.94

0.94

1.03

1.05

1.05

1.25

0.99

0.99

T2 (0.125)

1.03

0.89

1.02

0.96

0.90

1.08

1.25

1.16

0.98

1.02

1.02

0.97

0.97

1.05

1.06

1.08

0.95

1.44

0.97

0.98

T3 (0.25)

0.92

1.00

1.01

0.94

1.03

1.03

1.13

1.00

0.96

1.00

1.10

1.03

0.93

0.99

1.06

0.97

0.84

1.06

0.98

1.00

T4 (0.5)

1.00

0.90

1.05

0.93

0.97

1.08

1.19

0.95

0.95

1.01

0.95

0.94

0.91

0.98

1.19

1.00

1.05

1.06

0.96

0.99

T5 (1.0)

0.79

0.77

0.84

0.82

0.79

0.81

1.06

0.79

0.82

0.83

0.78

0.69

0.81

0.84

0.89

0.74

0.79

0.63

0.81

0.78

PC

15.67

15.65

6.99

6.83

25.31

25.54

35.81

30.95

6.65

6.99

16.28

15.45

6.91

7.33

26.94

24.71

32.26

37.69

6.64

6.89

Key:   NC = Negative Control, VC = Vehicle control, PC = Positive Control, -S9 = Absence of metabolic activation, +S9 = Presence of metabolic activation, T1-T5 = Test Item concentration from lower to higher.


Table5          S9 Efficiency Check- Summary

Summary of S9 efficiency check

 

TA100

TA1535

Mean

SD

Mean

SD

VC Dimethyl Sulfoxide (-S9)

100.67

6.11

13.00

1.00

VC Dimethyl Sulfoxide (+S9)

99.00

3.00

12.33

0.58

PC Benzo[a]pyrene (-S9)

96.33

2.08

13.67

0.58

PC Benzo[a]pyrene (+S9)

673.67

11.24

315.00

12.29

Key:   VC = Vehicle control, PC = Positive control, -S9 = Absence of metabolic activation, +S9 = Presence of metabolic activation, SD = Standard Deviation.

Conclusions:
The registered substance, α,α-bis[4-(dimethylamino)phenyl]-4-(phenylamino)naphthalene-1-methanol (CAS Number: 6786-83-0; EC Number: 229-851-8) tested non-mutagenic (negative) in Salmonella typhimurium tester strains TA1537, TA1535, TA98, TA100 and TA102 with and without S9 metabolic activation system. The test was performed according to OECD TG 471 and in compliance with OECD Principles of Good Laboratory Practice.
Executive summary:

The mutagenicity of the test substance, α,α-bis[4-(dimethylamino)phenyl]-4-(phenylamino)naphthalene-1-methanol (CAS Number: 6786-83-0; EC Number: 229-851-8) was tested according to OECD 471 using Salmonella typhimurium tester strains TA1537, TA1535, TA98, TA100 and TA102. The test was performed as two independent experiments according to the plate incorporation method (Trial I) and the preincubation method (Trial II), both in the presence and absence of rat liver microsomal activation (S9 mix). Concentrations used in the mutagenicity assay were selected based on a preliminary cytotoxicity assay. This preliminary cytotoxicity assay was performed using concentrations of 0.0000128, 0.000064, 0.00032, 0.0016, 0.008, 0.04, 0.2 and 1 mg/plate, with and without metabolic activation (10 % v/v S9 mix) using TA98 and TA100 strains. A slight reduction in the revertant counts and moderate inhibition of the background lawn was observed at 1mg/plate, and no reduction in the revertant count and/or inhibition in the background lawn was noted at concentrations from 0.0000128 to 0.2 mg/plate when compared to the vehicle control data. Based on the observations of the pre-test, the following doses were applied in the mutagenicity test: 0.0 (NC), 0.0 (VC), 0.0625, 0.125, 0.25, 0.5 and 1mg/plate, both in the presence and absence of metabolic activation, along with the negative, vehicle and positive controls. Trial I was performed according to the plate incorporation method. The test substance, together with the negative, vehicle and positive controls, were tested in triplicates. The Test Item doses were selected using a spacing factor of 2. There was slight precipitation, a slight reduction in revertant colony count and a moderate inhibition in the background lawn at 1 mg/plate. Furthermore, there was no increase in the number of revertant colonies and/or diminution of the background lawn at concentrations of 0.0625 - 0.5 mg/plate, neither in the presence nor the absence of metabolic activation compared to the vehicle control data. Trial II was performed to confirm the negative results observed in Trial I. Trial II was conducted according to the preincubation method; the substance was tested in all the tester strains in triplicates. There was slight precipitation, a slight reduction in revertant colony count and a moderate inhibition in the background lawn at 1 mg/plate. There was no increase in the number of revertant colonies and/or diminution of the background lawn at concentrations of 0.0625 - 0.5 mg/plate, neither in the presence nor in the absence of metabolic activation when compared to the vehicle control data. The numbers of revertant colonies of the vehicle (spontaneous revertant colonies) and positive controls (induced revertant colonies) of all the tester strains were within the range of historical data of the laboratory. The positive controls used in the study produced significant increases in the mean number of revertant colonies under both activated and non-activated conditions in all tester strains compared to the vehicle control data confirming the validity of the mutagenicity test. Based on the results of this study, it is concluded that(4-anilino-1-naphthyl){bis[4-(dimethylamino)phenyl]}methanol (CAS No. 6786-83-0) is non-mutagenic as it does not induce gene mutations (point and frameshift) in the histidine operon by base-pair changes or frameshifts, in the presence or the absence of metabolic activation system, in any of the five tester strains of Salmonella typhimurium (TA1537, TA1535, TA98, TA100 and TA102).

Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
The study contains experimental data of the registered substance.
Qualifier:
according to guideline
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosomal Aberration Test)
Version / remarks:
Adopted: 29 July 2016
GLP compliance:
yes
Type of assay:
in vitro mammalian chromosome aberration test
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Lot/batch number of test material: KCP/FS/742/20
- Purity: 99.62%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room Temperature (20 to 30oC)


OTHER SPECIFICS
-Solubility: The Test Item was found to be soluble up to 10 mg/ml in dimethyl sulfoxide.
-Precipitation of Test Item was performed by adding 50 µl of the Test Item solution (10 mg/ml) to 4.950 ml of culture media to attain 0.1 mg/ml. No precipitation was observed at a tested concentration of 0.1 mg/ml.

Species / strain / cell type:
Chinese hamster Ovary (CHO)
Details on mammalian cell type (if applicable):
CELLS USED
- Type and source of cells: NCCS, Pune, India
- Suitability of cells: CHO Cell lines are a commonly used test system for in vitro chromosomal aberration tests. The CHO cell line is recommended in OECD 473 (29th July 2016), and it meets the requirements of most regulatory agencies..

MEDIA USED
- Type and composition of media, CO2 concentration, humidity level, temperature, if applicable: CHO cells were cultured in complete RPMI-1640 medium (10 % Fetal bovine serum), and maintained at 37±2 °C, 5% CO2, in a CO2 incubator
Metabolic activation:
with and without
Metabolic activation system:
- source of S9 : A combination of phenobarbitone and β-naphthoflavone-induced rat liver microsomal enzymes (S9 homogenate) prepared in-house was used for the assay
- method of preparation of S9 mix: Prior to treatment freshly prepared S9 mix was used, an appropriate quantity of S9 fraction was thawed and mixed with co-factor solution to obtain a final concentration of 1% v/v as mentioned below. Cofactor solution: Glucose-6-phosphate [180 mg/ml], NADP [25 mg/ml] and Potassium chloride [150 mM] ) to obtain a final concentration of 1% v/v.Type and composition of metabolic activation system:
- concentration or volume of S9 mix and S9 in the final culture medium : 1 v/v%
Test concentrations with justification for top dose:
Test concentrations: 0.0 (VC), 0.0 (NC), 0.0015625, 0.003125 and 0.00625 mg/ml

Justification: The test concentrations were selected based on the solubility, precipitation and pH checks, as well as a preliminary cytotoxicity test. The substance was soluble in DMSO at a 0.1 mg/ml concentration. No precipitation was observed at the concentration of 0.1 mg/ml. The preliminary cytotoxicity assay was performed with test substance concentrations of 0.0 (NC), 0.0 (VC), 0.00625, 0.0125, 0.025, 0.05, 1.0 mg/ml. Excessive cytotoxicity (defined by a Relative Increase in Cell Count [RICC] of ≤40% of the concurrent vehicle control data) was observed for the Test Item concentrations from ≥0.0125 mg/ml, both in the presence and absence of metabolic activation. RICC decreased by 55±5% compared to vehicle control at 0.00625 mg/ml in the presence and absence of metabolic activation. Hence, 0.00625 mg/ml was selected as the highest test concentration.
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: Dimethyl sulfoxide

- Justification for choice of solvent/vehicle: The substance was insoluble in distilled water and was soluble in dimethyl sulfoxide up to 10 mg/ml.
Untreated negative controls:
yes
Remarks:
Distilled water
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
True negative controls:
no
Positive controls:
yes
Positive control substance:
benzo(a)pyrene
methylmethanesulfonate
Details on test system and experimental conditions:
NUMBER OF REPLICATIONS:
- Number of cultures per concentration (single, duplicate, triplicate): Single cultures were used.
- Number of independent experiments: Phase I (4-hour treatment, without S9), Phase II (4hrs treatment with S9), Phase III (24 hrs treatment without S9)

METHOD OF TREATMENT/ EXPOSURE:
- Cell density at seeding (if applicable): 1 × 10^6 cells/flask
- Test substance added in medium; in agar (plate incorporation); preincubation; in suspension; as impregnation on paper disk: in medium

TREATMENT AND HARVEST SCHEDULE:
- Preincubation period, if applicable:NA
- Exposure duration/duration of treatment: 4hrs (Phase I-II), 24 hrs (Phase III)
- Harvest time after the end of treatment (sampling/recovery times): Recovery period: 20 hrs (Phase I-II), Harvest time: 24 hrs (Phase I-III)

FOR CHROMOSOME ABERRATION AND MICRONUCLEUS:
- Spindle inhibitor (cytogenetic assays): indicate the identity of mitotic spindle inhibitor used (e.g., colchicine), its concentration and, duration and period of cell exposure: Two hours before cell harvest, colchicine (final concentration of 1 µg/ml) was added to cultures and incubated at 37 ±2 °C, 5 % CO2.
- Methods of slide preparation and staining technique used including the stain used (for cytogenetic assays): Each cell suspension obtained after harvesting was dropped on a clean chilled slide using the hanging drop method and kept for drying on a slide warmer. Duplicate slides were prepared from each culture.

- Number of cells spread and analysed per concentration (number of replicate cultures and total number of cells scored): At least 300 well-spread metaphases per concentration (single culture) were analysed using 100x magnification for the incidence of structural aberrations.
- Criteria for scoring chromosome aberrations (selection of analysable cells and aberration identification): Cells with structural chromosomal aberration(s) including and excluding gaps were scored. Chromatid and chromosome-type aberrations were recorded separately and classified by sub-types (breaks, exchanges). Cells that contain the number of centromeres equal to the number 2n ± 2 were scored.

METHODS FOR MEASUREMENT OF CYTOTOXICITY
- Method, e.g.: background growth inhibition; mitotic index (MI); relative population doubling (RPD); relative increase in cell count (RICC); replication index; cytokinesis-block proliferation index; cloning efficiency; relative total growth (RTG); relative survival (RS); other: The cytotoxicity was evaluated based on the reduction in the Relative Increase in Cell Counts (RICC). The concentration, which yielded 55±5% cytotoxicity, i.e., reduction in RCC to 45±5% of the concurrent vehicle control, was selected as the highest test concentration. Two lower concentrations using spacing factor 2 were selected as middle and low test concentrations.
Evaluation criteria:
The substance was considered to be clearly positive if, in any of the experimental conditions examined:
- At least one of the test concentrations exhibits a significant increase compared with the concurrent negative/vehicle control,
- The increase is dose-related when evaluated with an appropriate trend test,
- Any of the results are outside of the distribution of the laboratory historical negative/vehicle control database
When all these criteria were met, the Test Item was then considered to induce chromosomal aberrations in cultured mammalian cells in this test system.

The substance was considered clearly negative if, in all experimental conditions examined:
- None of the test concentrations exhibits a significant increase compared with the concurrent negative/vehicle control.
- There is no concentration-related increase when evaluated with an appropriate trend test.
- The results are inside the distribution of the laboratory historical negative control database.
Statistics:
Statistical analysis was performed to assess a possible dose-dependent increase of aberrant cell frequencies using Fisher’s Exact Test (NCSS statistics software). The percentage of aberrant cells from the Test Item treated group was compared to the solvent control groups. A trend is judged as significant whenever the p-value (probability value) is below 0.05.
Key result
Species / strain:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
Cytotoxicity was 55.79%, (without S9, Phase I), 54.96% (with S9, Phase II) and 51.24 % (without S9, in Phase III) observed at 0.00625 mg/ml.
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
True negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
Solubility and precipitation check: The substance was soluble in dimethyl sulfoxide at 10 mg/ml concentration. No precipitation was observed at the concentration of 0.1 mg/ml.
pH check: The substance at concentration of 0.1 mg/ml did not induce alteration of the pH of medium at 0 and 4 hours incubation.

Preliminary cytotoxicity test: In the preliminary cytotoxicity assay, excessive cytotoxicity (defined by a Relative Increase in Cell Count [RICC] of ≤40% of the concurrent vehicle control data) was observed for the Test Item concentrations from ≥0.0125 mg/ml, both in the presence and absence of metabolic activation. RICC decreased by 55±5% compared to vehicle control at 0.00625 mg/ml both in the presence and absence of metabolic activation
Remarks on result:
other: No mutagenic potetial was observed

Appendix1: Relative Increase in Cell Counts – Preliminary Cytotoxicity Assay

 

Dose

Level

Conc.

(mg/ml)

Absence of Metabolic activation

Presence of Metabolic activation

Cell count

RICC

% Cytotoxicity

Cell count

RICC

% Cytotoxicity

Starting

Final

Starting

Final

NC

Distilled water

1000000

3650000

100.00

0.00

1000000

3680000

100.00

0.00

VC

DMSO

1000000

3620000

98.87

1.13

1000000

3650000

98.88

1.12

T1

0.00625

1000000

2140000

43.51

56.49

1000000

2210000

45.66

54.34

T2

0.0125

1000000

1280000

10.69

89.31

1000000

1320000

12.08

87.92

T3

0.025

1000000

0

0.00

100.00

1000000

0

0.00

100.00

T4

0.05

1000000

0

0.00

100.00

1000000

0

0.00

100.00

T5

0.1

1000000

0

0.00

100.00

1000000

0

0.00

100.00

Key: NC = Negative Control, VC = Vehicle Control, Conc. = Concentration, mg = milligram, ml = milliliter, RICC = Relative Increase in Cell Counts, % = percentage.


Appendix 2: Relative Increase in Cell Counts- Main Study

 

Dose

Level

Conc.

 

Phase I -Absence of Metabolic activation

Cell count

RICC

% Cytotoxicity

Starting

Final

NC

Distilled water

1000000

3620000

100.00

0.00

VC

DMSO

1000000

3590000

98.85

1.15

T1

0.015625 mg/ml

1000000

2840000

71.04

28.96

T2

0.003125 mg/ml

1000000

2580000

61.00

39.00

T3

0.00625 mg/ml

1000000

2145000

44.21

55.79

PC

20 µg/ml

1000000

2560000

60.23

39.77

 

Dose

Level

Conc.

Phase II -Presence of Metabolic activation

Cell count

RICC

% Cytotoxicity

Starting

Final

NC

Distilled water

1000000

3640000

100.00

0.00

VC

DMSO

1000000

3580000

97.73

2.27

T1

0.015625 mg/ml

1000000

2920000

74.42

25.58

T2

0.003125 mg/ml

1000000

2684000

65.27

34.73

T3

0.00625 mg/ml

1000000

2162000

45.04

54.96

PC

30 µg/ml

1000000

2540000

59.69

40.31

 

Dose

Level

Conc.

Phase III -Absence of Metabolic activation

Cell count

RICC

% Cytotoxicity

Starting

Final

NC

Distilled water

1000000

3612000

100.00

0.00

VC

DMSO

1000000

3420000

92.65

7.35

T1

0.015625 mg/ml

1000000

2785000

73.76

26.24

T2

0.003125 mg/ml

1000000

2540000

63.64

36.36

T3

0.00625 mg/ml

1000000

2180000

48.76

51.24

PC

20 µg/ml

1000000

2560000

64.46

35.54

Key: NC = Negative Control, VC = Vehicle Control, PC = Positive Control, Conc. = Concentration, mg = milligram, ml = milliliter, µg = microgram, RICC = Relative Increase in Cell Counts, % = percentage.


Appendix 3:Individual Data on Chromosome Aberrations-Phase I:Absence of metabolic activation (short term)

 

Dose level

&

Concentration

No. of Metaphases

Frequencies of Aberration

Total No of Aberrant cells

 with gap

without gap

NC

(Distilled wate)

300

-

0

0

VC

(DMSO)

300

1 Ctb

1

1

T1

0.0015625 mg/ml

300

2 fragments

2

2

T2

0.003125 mg/ml

300

1 ring, 1 fragment

2

2

T3

0.00625 mg/ml

300

1 Ctg, 1 Ctb

2

1

PC

20 µg/ml

300

1 Csg, 9 Ctb, 3 fragment, 2 ring, 3 exchange,

4 dic

21

20

 Key: NC = Negative control (distilled water), VC = Vehicle Control (dimethyl sulfoxide), PC = Positive Control (methyl methanesulfonate), mg = milligram, µg = microgram, ml = milliliter, T3- T1 = Test Item concentration from higher to lower, Ctg = Chromatid gap, Csg = Chromosome gap, Ctb = Chromatid break, Csb = Chromosome break, dic = dicentric.

 


 

Appendix 4:Individual Data on Chromosome Aberrations- Phase II:Presence ofmetabolic activation (short term)

Dose level

&

Concentration

No. of Metaphases

Frequencies of Aberration

Total No of Aberrant cells

 with gap

without gap

NC

0 mg/ml

300

-

0

0

VC

0 mg/ml

300

-

0

0

T1

0.0015625 mg/ml

300

1 Ctb, 1 dic

2

2

T2

0.003125 mg/ml

300

1 Ctb

1

1

T3

0.00625 mg/ml

300

-

0

0

PC

30 µg/ml

300

9 Ctb, 8 fragment, 3 ring, 2 exchange, 3 dic,

1 minute

22

22

 

Key: NC = Negative control (distilled water), VC = Vehicle Control (dimethyl sulfoxide), PC = Positive Control (methyl methanesulfonate), mg = milligram, µg = microgram, ml = milliliter, T3-T1 = Test Item concentration from higher to lower, Ctg = Chromatid gap, Csg = Chromosome gap, Ctb = Chromatid break, Csb = Chromosome break, dic = dicentric.


           

Appendix 5: Individual Data on Chromosome Aberrations- Phase III:Absenceof metabolic activation (Continuous)

 

Dose level

&

Concentration

No. of Metaphases

Frequencies of Aberration

Total No of Aberrant cells

with gap

without gap

NC

0 mg/ml

300

-

0

0

VC

0 mg/ml

300

1 Ctb

1

1

T1

0.0015625 mg/ml

300

-

0

0

T2

0.003125 mg/ml

300

1 ring, 1 Csb, 1 fragment

3

3

T3

0.00625 mg/ml

300

1 Ctb, 1 dic

2

2

PC

20 µg/ml

300

9 Ctb, 1 Csb, 5 fragment, 1 ring, 2 exchange,

7 dic

23

23

Key: NC = Negative Control (distilled water), VC = Vehicle Control (dimethyl sulfoxide), PC = Positive Control (methyl methanesulfonate), mg = milligram, µg = microgram, ml = milliliter, T3-T1 = Test Item concentration from higher to lower, Ctg = Chromatid gap, Csg = Chromosome gap, Ctb = Chromatid break, Csb = Chromosome break, dic = dicentric.

 


 

Appendix 6: Summary Dataon Chromosome Aberrations - Phase I

 

Dose Level

Concentration

 

Absence of metabolic activation

Total No. of Aberrant cells without gap

 Percent aberrant cells

 

NC

Distilled water

0

0.00

 

VC

DMSO

1

0.33

 

T1

0.015625 mg/ml

2

0.67

 

T2

0.003125 mg/ml

2

0.67

 

T3

0.00625 mg/ml

1

0.33

 

PC

20 µg/ml*

20

6.67

 

Key: NC = Negative Control (distilled water), VC = Vehicle Control (dimethyl sulfoxide), PC = Positive Control, mg = milligram, ml = milliliter, µg = microgram,* = Statistical significant increase in % aberrant cell (p<0.05).

 


 

Appendix 7:Summary Data on Chromosome Aberrations - Phase II

 

 

Dose Level

Concentration

 

Presence of metabolic activation

Total No. of Aberrant cells without gap

Percent aberrant cells

 

NC

Distilled water

0

0.00

 

VC

DMSO

0

0.00

 

T1

0.015625 mg/ml

2

0.67

 

T2

0.003125 mg/ml

1

0.33

 

T3

0.00625 mg/ml

0

0.00

 

PC

30 µg/ml*

22

7.33

 

Key: NC = Negative Control (distilled water), VC = Vehicle Control (dimethyl sulfoxide), PC = Positive Control, mg = milligram, ml = milliliter, µg = microgram,* = Statistical significant increase in % aberrant cell (p<0.05).


 

Appendix 8: SummaryData on Chromosome Aberrations - Phase III

 

Dose Level

Concentration

Absence of metabolic activation

Total No. of Aberrant cells without gap

Percent aberrant cells

 

NC

Distilled water

0

0.00

 

VC

DMSO

1

0.33

 

T1

0.015625 mg/ml

0

0.00

 

T2

0.003125 mg/ml

3

1.00

 

T3

0.00625 mg/ml

2

0.67

 

PC

20 µg/ml*

23

7.67

 

Key: NC = Negative Control (distilled water), VC = Vehicle Control (dimethyl sulfoxide), PC = Positive Control, mg = milligram, ml = milliliter, µg = microgram,* = Statistical significant increase in % aberrant cell (p<0.05).

Conclusions:
The registered substance, (4-anilino-1-naphthyl){bis[4-(dimethylamino)phenyl]}methanol (CAS No. 6786-83-0) did not induce chromosomal aberration up to 0.00625 mg/ml either in the presence or absence of S9 metabolic activation system in CHO cells. The test was performed according to OECD TG 473 and in compliance with GLP.
Executive summary:

The potential of (4-anilino-1-naphthyl){bis[4-(dimethylamino)phenyl]}methanol (CAS No. 6786-83-0) to induce structural chromosomal aberration was tested according to OECD TG 473 with and without metabolic activation in cultured Chinese Hamster Ovary (CHO) cells. Cofactor-supplemented liver S9 microsomal fraction was used as an exogenous metabolic activation. The S9 fraction was obtained from phenobarbitone and β-naphthoflavone-injected rats. The substance was insoluble in distilled water but was soluble in dimethyl sulfoxide up to 10 mg/ml. Test concentrations were chosen based on a preliminary cytotoxicity experiment. In this pre-test, CHO cells were exposed to 0.0 (VC), 0.0 (NC), 0.00625, 0.0125, 0.025, 0.05 and 0.1 mg/ml for 4 hours in the presence (1 % v/v S9 mix) and absence of metabolic activation system. Excessive cytotoxicity (defined by a Relative Increase in Cell Count [RICC] of <40% of the concurrent vehicle control data) was observed for the Test Item concentrations at ≥0.0125 mg/ml, both in the presence and absence of metabolic activation. RICC decreased by 55±5% compared to vehicle control at 0.00625 mg/ml both in the presence and absence of metabolic activation. Hence, Phase I (short term[4hrs]exposure in the absence of metabolic activation), Phase II (short term[4 hrs]exposure in the presence of metabolic activation) and Phase III (continuous[24 hrs]exposure in the absence of metabolic activation) were conducted with the Test Item at the concentrations of 0.0015625, 0.003125 and 0.00625 mg/ml, along with vehicle (DMSO), negative (Distilled water) and concurrent positive (Methyl methanesulfonate, 20µg/ml, without S9 mix;Benzo (a) pyrene, 30µg/ml with S9 mix)controls. At least 300 well-spread metaphases per concentration (single culture) were analyzed using 100x magnification for the incidence of structural aberrations. Breaks (chromatid and chromosomal), gaps(chromatid and chromosomal), rings and fragments, and dicentric chromosomes were found as structural chromosome aberrations. Gaps were recorded and reported separately but not included in the total aberration frequency.Results:In Phase I experiment, CHO cells were exposed to the substance, vehicle, negative and positive controls for 4 hours (short term exposure) in the absence of metabolic activation. The average RICC values were 98.85 % (vehicle control), 71.04 % (at 0.0015625 mg/ml), 61.00 % (at 0.003125 mg/ml) and 44.21 % (at 0.00625 mg/ml). No significant increase in mean percent aberrant cells was observed at 0.0015625 mg/ml (mean % aberrant cells: 0.67%), 0.003125 mg/ml (mean % aberrant cells: 0.67%), or at 0.00625 mg/ml (mean % aberrant cells: 0.33%) compared to the vehicle control data (mean % aberrant cells 0.33 %). In Phase II experiment, cultures were exposed to the substance, vehicle, negative and positive controls for 4 hours (short term exposure) in the presence of metabolic activation (1 % v/v S9 mix). The average RICC values were 97.73 % (vehicle control), 74.42 % (at 0.0015625 mg/ml), 65.27 % (at 0.003125 mg/ml) and 45.04 % (at 0.00625 mg/ml). No significant increase in mean percent aberrant cells was observed at 0.0015625 mg/ml (mean % aberrant cells: 0.67%), 0.003125 mg/ml (mean % aberrant cells: 0.33%), or at 0.00625 mg/ml (mean % aberrant cells: 0.00%) compared to the vehicle control data (mean % aberrant cells: 0.00 %). In Phase III, cultures were exposed to the substance, vehicle, negative and positive control for 24 hours (continuous exposure) without metabolic activation. The average RICC values were 92.65 % (vehicle control), 73.76 % (at 0.0015625 mg/ml), 63.64 % (at 0.003125 mg/ml) and 48.76 % (at 0.00625 mg/ml). No significant increase in mean percent aberrant cells was observed at 0.0015625 mg/ml (mean % aberrant cells: 0.00%), 0.003125 mg/ml (mean % aberrant cells: 1.00%), or at 0.00625 mg/ml (mean % aberrant cells: 0.67%) compared to the vehicle control data (mean % aberrant cells 0.33 %). In all phases of the study, no significant reduction in RICC (cytotoxicity) and no increase in percent aberrant cells were observed in vehicle control (DMSO) either in the presence or absence of metabolic activation, when compared to the negative control (distilled water). The positive controls (-S9: methyl methanesulfonate, +S9: Benzo[a]pyrene) used in the study produced statistically significant increases in the percent of cells with structural chromosome aberrations (Phase I: 6.67%; p<0.0001, Phase II: 7.33%; p<0.0001, Phase III: 7.67%; p<0.0001) indicating the sensitivity of the test system to specific mutagens and confirmed that the test conditions were appropriate and that the metabolic activation system functioned properly.Conclusion:The registered substance, (4-anilino-1-naphthyl){bis[4-(dimethylamino)phenyl]}methanol (CAS No. 6786-83-0) did not induce chromosomal aberration up to the highest concentration of 0.00625mg/ml, either in the presence or absence of S9 metabolic activation in CHO cells.

Endpoint:
in vitro gene mutation study in mammalian cells
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
The study contains experimental data of the registered substance.
Qualifier:
according to guideline
Guideline:
OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test using the Hprt and xprt genes)
Version / remarks:
OECD 476 (Adopted July 29 2016)
GLP compliance:
yes
Type of assay:
in vitro mammalian cell gene mutation test using the Hprt and xprt genes
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Lot/batch number of test material: KCP/FS/439/21
- Expiration date of the lot/batch: 09-11-2022
- Purity: >90%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room Temperature (20 to 30oC)

OTHER SPECIFICS
-Solubility:The Test Item was found to be soluble up to 50 mg/ml in dimethyl formamide.
-Precipitation of Test Item was performed by adding 50 µl of Test Item formulation (50 mg/ml) to 4.95 ml of culture media to attain 0.5 mg/ml. Slight precipitation was observed at the tested concentrations of 0.5 mg/ml, which was considered not to interfere with the conduct of the study.
Target gene:
hypoxanthine-guanine phosphoribosyltransferase (Hprt)
Species / strain / cell type:
Chinese hamster Ovary (CHO)
Details on mammalian cell type (if applicable):
CELLS USED
- Type and source of cells: NCCS, Pune, India
- Suitability of cells: CHO cell lines are commonly used for in vitro mammalian cell gene mutation assays because of the stable karyotype, relatively low spontaneous mutant frequency and sensitivity to various chemical mutagens.

MEDIA USED
- Type and composition of media, CO2 concentration, humidity level, temperature, if applicable: CHO cells were cultured in complete RPMI-1640 medium (10 % Fetal bovine serum), 100 units Penicillin/ml, 10 µg Streptomycin/ml, and incubated at 37±2 °C, 5% CO2, in a CO2 incubator
Metabolic activation:
with and without
Metabolic activation system:
Type and composition of metabolic activation system:
- source of S9 : A combination of phenobarbital and β-naphthoflavone-induced rat liver microsomal enzymes (S9 homogenate) prepared at the test facility.
- method of preparation of S9 mix: 2 ml of S9 fraction was thawed and mixed with 1 ml of 180 mg/ml Glucose-6-phosphate, 1 ml of 25 mg/ml NADP and 1 ml of 150 mM Potassium chloride (cofactor solution) to obtain a concentration of 40% v/v S9 in Cofactor mix.
- concentration or volume of S9 mix and S9 in the final culture medium : A volume of 2.5 ml S9 cofactor mix (40%) was added to 100 ml of culture medium to achieve 1 % v/v S9 in the culture medium.
Test concentrations with justification for top dose:
Test concentrations: 0 (Negative control), 0 (Vehicle control), 0.001875, 0.00375, 0.0075 and 0.015 mg/ml

Justification: Test concentrations were selected based on the solubility, precipitation and pH checks as well as a preliminary cytotoxicity test. The test substance was soluble in dimethylformamide up to 50 mg/ml. Slight precipitation was observed at 0.5 mg/ml under the actual testing conditions, which did not interfere with the conduct of the study. The initial cytotoxicity test was performed with concentrations of 0.0 (NC), 0.0 (VC), 0.03125, 0.0625, 0.125, 0.25, and 0.5 mg/ml in the presence and absence of S9 metabolic activation system. Complete cytotoxicity (determined by the Relative Survival [RS is cloning efficiency (CE) of cells plated immediately after treatment adjusted by any loss of cells during treatment as compared with cloning efficiency in vehicle control]) was observed at tested concentrations of 0.03125-0.5 mg/ml both in the presence and absence of metabolic activation. Hence, the preliminary cytotoxicity test was repeated with the concentrations of 0.0 (NC), 0.0 (VC), 0.001875, 0.00375, 0.0075, 0.015 and 0.03 mg/ml. The concentration of 0.03 mg/ml was cytotoxic in the absence and presence of metabolic activation. Limited cytotoxicity (within the recommended range of 10-20% RS) was observed at 0.015 mg/ml. Hence, in the main test, the following test concentrations were selected: 0.001875, 0.00375, 0.0075 and 0.015 mg/ml, with and without the S9 metabolic activation system.
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: Dimethylformamide
- Justification for choice of solvent/vehicle: Based on the solubility of the test item, dimethylformamide was used as a vehicle.
- Justification for percentage of solvent in the final culture medium: The Test Item was found to be insoluble in distilled water, but was soluble in dimethylformamide up to 50 mg/ml.

Untreated negative controls:
yes
Remarks:
Distilled water
Negative solvent / vehicle controls:
yes
Remarks:
Dimethylformamide
True negative controls:
no
Positive controls:
yes
Positive control substance:
benzo(a)pyrene
ethylmethanesulphonate
Details on test system and experimental conditions:
NUMBER OF REPLICATIONS:
- Number of cultures per concentration: Single
- Number of independent experiments: One

METHOD OF TREATMENT/ EXPOSURE:
- Cell density at seeding (if applicable): 10 x 10^6 cells
- Test substance added in medium: Complete RPMI-1640 medium (10 % Fetal bovine serum)

TREATMENT AND HARVEST SCHEDULE:
- Exposure duration/duration of treatment:4 hours at 37°C

FOR GENE MUTATION:
- Expression time (cells in growth medium between treatment and selection): 7 days
- Fixation time (start of exposure up to fixation or harvest of cells): 16 day (7-day expression time and and 9-day culturing on selective medium)

METHODS FOR MEASUREMENT OF CYTOTOXICITY
- Method: Cytotoxicity was determined by the relative survival (RS), i.e. cloning efficiency measured immediately after treatment and adjusted for any cell loss during treatment as compared to the vehicle control. The maximum test concentration that yielded 20 and 10% RS value were selected as the highest test concnetration.
- Any supplementary information relevant to cytotoxicity: Limited cytotoxicity was observed up to the highest tested concentration, i.e. 0.015 mg/ml, either in the absence (RS: 18.73%) or presence (RS: 17.45%) of metabolic activation.
Evaluation criteria:
The test chemical was considered to be clearly positive if in any of the experimental conditions examined:
a)at least one of the test concentrations exhibited a statistically significant increase compared with the concurrent negative control,
b) the increase was concentration-related when evaluated with an appropriate trend test,
c) any of the results were outside the distribution of the laboratory negative control data.
When all of these criteria were met, the test chemical was then considered able to induce gene mutations in cultured mammalian cells in this test system.

The test chemical was considered clearly negative if, in all experimental conditions examined:
a) none of the test concentrations exhibited a significant increase compared with the concurrent negative control,
b) all results were inside the distribution of the laboratory negative control data.
The test chemical was then considered unable to induce gene mutations in cultured mammalian cells in this test system.
Statistics:
Statistical analysis was performed to assess a possible dose-dependent increase of mutation frequency using Fisher’s Exact Test (NCSS statistics software). The mutation frequency of the TestItem-treated group was compared to the solvent control groups. A trend is judged as significant whenever the p-value (probability value) is below 0.05.
Key result
Species / strain:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
Limited cytotoxicity was observed at 0.015 mg/ml, either in the absence (RS: 18.73%) or presence (RS: 17.45%) of metabolic activation.
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
True negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Data on pH: To determine the changes in the pH of the medium, 50 µl of the Test Item formulation was added to 4.95 ml of complete medium, resulting in a final Test Item concentration of 0.5 mg/ml in the medium. There was no alteration of the pH after 0 and 4 hrs incubation.
- Water solubility: Test chemical was insoluble in distilled water, but was soluble in dimethylformamide up to 50 mg/ml.
- Precipitation: Slight precipitation was observed at the tested concentrations of 0.5 mg/ml, which was considered not to interfere with the conduct of the study.


RANGE-FINDING/SCREENING STUDIES (if applicable):
Test concentrations were selected based on a preliminary cytotoxicity test.
The initial cytotoxicity test was performed with concentrations of 0.0 (NC), 0.0 (VC), 0.03125, 0.0625, 0.125, 0.25, and 0.5 mg/ml in the presence and absence of S9 metabolic activation system. Complete cytotoxicity (determined by the Relative Survival [RS is cloning efficiency (CE) of cells plated immediately after treatment adjusted by any loss of cells during treatment as compared with cloning efficiency in vehicle control]) was observed at tested concentrations of 0.03125-0.5 mg/ml both in the presence and absence of metabolic activation. Hence, the preliminary cytotoxicity test was repeated with the concentrations of 0.0 (NC), 0.0 (VC), 0.001875, 0.00375, 0.0075, 0.015 and 0.03 mg/ml. The concentration of 0.03 mg/ml was cytotoxic in the absence and presence of metabolic activation. Limited cytotoxicity (within the recommended range of 10-20% RS) was observed at 0.015 mg/ml. Hence, in the main test, the following test concentrations were selected: 0.001875, 0.00375, 0.0075 and 0.015 mg/ml, with and without the S9 metabolic activation system..
STUDY RESULTS
- Concurrent vehicle negative and positive control data: Data available. For tabular data refer to the section “Any additional information on results including tables”.
Gene mutation tests in mammalian cells:
- Results from cytotoxicity measurements: For tabular data, refer to the section “Any additional information on results including tables”.
- Genotoxicity results:
o Number of cells treated and sub-cultures for each culture: 10 x 10^6 cell/flask
o Number of cells plated in selective and non-selective medium: 2x10^5cells / 10 ml of cloning media were seeded in the presence of 10 µg/ml of 6-thioguanine (6TG) in triplicates. 100 cells / 10 ml of cloning media and then plated in 60 mm culture plates in triplicate to determine the cloning efficiency.
o Number of colonies in non-selective medium and number of resistant colonies in selective medium, and related mutant frequency: For tabular data, refer to the section “Any additional information on results incl tables”.
HISTORICAL CONTROL DATA (with ranges, means and standard deviation, and 95% control limits for the distribution as well as the number of data)
- Positive historical control data: Available but not shown.
- Negative (solvent/vehicle) historical control data: Available but not shown.
Remarks on result:
other: No mutagenic potential observed

Appendix1: Relative Survival – Preliminary Cytotoxicity Assay:Absence of metabolic activation

 

Dose

 level

Concentration

No. of Cells

No. of colonies

Mean Colony count

No. of

cells seeded

CE

Adjusted

 CE

RS

Before

After

R1

R2

R3

NC

Distilled water

20000000

23300000

-

-

-

-

-

-

-

-

VC

Dimethylformamide

20000000

22820000

-

-

-

-

-

-

-

-

T1

0.03125 mg/ml

20000000

0

-

-

-

-

-

-

-

-

T2

0.0625 mg/ml

20000000

0

-

-

-

-

-

-

-

-

T3

0.125 mg/ml

20000000

0

-

-

-

-

-

-

-

-

T4

0.25 mg/ml

20000000

0

-

-

-

-

-

-

-

-

T5

0.5 mg/ml

20000000

0

-

-

-

-

-

-

-

-

Key: NC = Negative Control, VC = Vehicle Control, T5 - T1= Test Item concentration from higher to lower, R = Replicate, CE = Cloning Efficiency, RS = Relative Survival, mg = milligram, ml = milliliter.

 

 

Appendix2:Relative Survival – Preliminary Cytotoxicity Assay: Presence of metabolic activation

 

Dose

 level

Concentration

No. of Cells

No. of colonies

Mean Colony count

No. of

cells seeded

CE

Adjusted

 CE

RS

Before

After

R1

R2

R3

NC

Distilled water

20000000

22980000

-

-

-

-

-

-

-

-

VC

Distilled water

20000000

22640000

-

-

-

-

-

-

-

-

T1

0.03125 mg/ml

20000000

0

-

-

-

-

-

-

-

-

T2

0.0625 mg/ml

20000000

0

-

-

-

-

-

-

-

-

T3

0.125 mg/ml

20000000

0

-

-

-

-

-

-

-

-

T4

0.25 mg/ml

20000000

0

-

-

-

-

-

-

-

-

T5

0.5 mg/ml

20000000

0

-

-

-

-

-

-

-

-

  Key: NC = Negative Control, VC = Vehicle Control, T5 - T1= Test Item concentration from higher to lower, R = Replicate, CE = Cloning Efficiency, RS = Relative Survival, mg = milligram, ml = milliliter.

 

 

Appendix 3: Relative Survival – Repeated Preliminary Cytotoxicity Assay: Absence of metabolic activation

 

Dose

 level

Concentration

No. of Cells

No. of colonies

Mean Colony count

No. of

cells seeded

CE

Adjusted

 CE

RS

Before

After

R1

R2

R3

NC

Distilled water

20000000

23650000

235

218

230

227.67

100

2.277

2.692

100.00

VC

Dimethylformamide

20000000

23260000

225

215

226

222.00

100

2.220

2.582

95.90

T1

0.001875 mg/ml

20000000

22820000

215

203

211

209.67

100

2.097

2.392

92.66

T2

0.00375 mg/ml

20000000

21620000

175

182

180

179.00

100

1.790

1.935

74.95

T3

0.0075 mg/ml

20000000

16680000

165

156

163

161.33

100

1.613

1.346

52.11

T4

0.015 mg/ml

20000000

8662000

116

105

114

111.67

100

1.117

0.484

18.73

T5

0.03 mg/ml

20000000

0

0

0

0

0.00

100

0.000

0.000

0.00

Key: NC = Negative Control, VC = Vehicle Control, T5 - T1= Test Item concentration from higher to lower, R = Replicate, CE = Cloning Efficiency, RS = Relative Survival, mg = milligram, ml = milliliter.

 

 

Appendix 4:Relative Survival – Repeated Preliminary Cytotoxicity Assay: Presence of metabolic activation

 

Dose

 level

Concentration

No. of Cells

No. of colonies

Mean Colony count

No. of

cells seeded

CE

Adjusted

 CE

RS

Before

After

R1

R2

R3

NC

Distilled water

20000000

23820000

224

236

232

230.67

100

2.307

2.747

100.00

VC

Dimethylformamide

20000000

23440000

215

226

235

225.33

100

2.253

2.641

96.13

T1

0.001875 mg/ml

20000000

22420000

216

211

209

212.00

100

2.120

2.377

89.99

T2

0.00375 mg/ml

20000000

19240000

185

193

173

183.67

100

1.837

1.767

66.90

T3

0.0075 mg/ml

20000000

16540000

158

163

168

163.00

100

1.630

1.348

51.04

T4

0.015 mg/ml

20000000

8862000

108

98

106

104.00

100

1.040

0.461

17.45

T5

0.03 mg/ml

20000000

0

0

0

0

0.00

100

0.000

0.000

0.00

  Key: NC = Negative Control, VC = Vehicle Control, T5 - T1= Test Item concentration from higher to lower, R = Replicate, CE = Cloning Efficiency, RS = Relative Survival, mg = milligram, ml = milliliter.

 

 

Appendix 5: RelativeSurvival – Main Study: Absence of metabolic activation

 

Dose

 level

Concentration

No. of Cells

No. of colonies

Mean Colony count

No. of

cells seeded

CE

Adjusted

 CE

RS

Before

After

R1

R2

R3

NC

Distilled water

20000000

23440000

232

224

229

228.33

100

2.283

2.676

100.00

VC

Dimethylformamide

20000000

23140000

221

224

218

221.00

100

2.210

2.557

95.55

T1

0.001875 mg/ml

20000000

21820000

216

210

212

212.67

100

2.127

2.320

90.74

T2

0.00375 mg/ml

20000000

19280000

190

197

194

193.67

100

1.937

1.867

73.01

T3

0.0075 mg/ml

20000000

16660000

168

162

157

162.33

100

1.623

1.352

52.88

T4

0.015 mg/ml

20000000

8140000

122

113

119

118.00

100

1.180

0.480

18.78

PC

400 µg/ml

20000000

21480000

219

214

208

213.67

100

2.137

2.295

89.75

  Key: NC = Negative Control, VC = Vehicle Control, PC = Positive Control (Ethylmethanesulfonate), T4-T1= Test Item concentration from higher to lower, R = Replicate, CE = Cloning Efficiency, RS = Relative Survival, mg = milligram, µg =microgram, ml = milliliter.

 

 

 

Appendix 6:Relative Survival – Main Study: Presence of metabolic activation

 

Dose

 level

Concentration

No. of Cells

No. of colonies

Mean Colony count

No. of

cells seeded

CE

Adjusted

 CE

RS

Before

After

R1

R2

R3

NC

Distilled water

20000000

23320000

230

221

221

224.00

100

2.240

2.612

100.00

VC

Dimethylformamide

20000000

23020000

218

224

216

219.33

100

2.193

2.525

96.66

T1

0.001875 mg/ml

20000000

21180000

203

209

211

207.67

100

2.077

2.199

87.11

T2

0.00375 mg/ml

20000000

18720000

186

180

182

182.67

100

1.827

1.710

67.73

T3

0.0075 mg/ml

20000000

15820000

162

154

168

161.33

100

1.613

1.276

50.55

T4

0.015 mg/ml

20000000

8524000

110

111

108

109.67

100

1.097

0.467

18.51

PC

30 µg/ml

20000000

20960000

210

215

211

212.00

100

2.120

2.222

88.01

  Key: NC = Negative Control, VC = Vehicle Control, PC = Positive Control (Benzo[a]pyrene), T4-T1= Test Item concentration from higher to lower, R = Replicate, CE = Cloning Efficiency, RS = Relative Survival, mg = milligram, µg =microgram, ml = milliliter.

 

 

 

 

Appendix 7:Cloning Efficiency(Non-selective medium)Main Study: Absence of metabolic activation

 

Dose level

Non Selective medium

Concentration

No. of cells

 seeded

No. of colonies

Mean No. of colonies

CE

R1

R2

R3

NC

Distilled water

100

214

221

211

215

2.15

VC

Dimethylformamide

100

213

206

211

210

2.10

T1

0.001875 mg/ml

100

186

190

192

189

1.89

T2

0.00375 mg/ml

100

179

182

190

184

1.84

T3

0.0075 mg/ml

100

184

181

176

180

1.80

T4

0.015 mg/ml

100

176

177

170

174

1.74

PC

400 µg/ml

100

165

174

179

173

1.73

Key: NC = Negative Control, VC = Vehicle Control, PC = Positive Control (Ethylmethanesulfonate), T4-T1= Test Item concentration from higher to lower, R = Replicate, CE = Cloning Efficiency, RS = Relative Survival, mg = milligram, µg =microgram, ml = milliliter.

 

 

 

Appendix 8: CloningEfficiency(Non-selective medium)Main Study: Presence of metabolic activation

 

Dose level

Non Selective medium

Concentration

No. of cells

 seeded

No. of colonies

Mean No. of colonies

CE

R1

R2

R3

NC

Distilled water

100

220

218

217

218

2.18

VC

Dimethylformamide

100

211

198

216

208

2.08

T1

0.001875 mg/ml

100

189

184

195

189

1.89

T2

0.00375 mg/ml

100

186

179

184

183

1.83

T3

0.0075 mg/ml

100

181

168

174

174

1.74

T4

0.015 mg/ml

100

178

168

174

173

1.73

PC

30 µg/ml

100

168

174

178

173

1.73

 

Key: NC = Negative Control, VC = Vehicle Control, PC = Positive Control (Benzo[a]pyrene), T4-T1= Test Item concentration from higher to lower, R = Replicate, CE = Cloning Efficiency, RS = Relative Survival, mg = milligram, µg =microgram, ml = milliliter

 

Appendix 9: Cloning Efficiency(Selective medium):Absence of metabolic activation

 

Dose level

Selective medium

Concentration

No. of cells

 seeded

No. of colonies

Mean No. of colonies

CE

R1

R2

R3

NC

Distilled water

200000

4

4

2

3.33

0.00001667

VC

Dimethylformamide

200000

3

5

3

3.67

0.00001833

T1

0.001875 mg/ml

200000

4

4

3

3.67

0.00001833

T2

0.00375 mg/ml

200000

3

4

3

3.33

0.00001667

T3

0.0075 mg/ml

200000

4

3

4

3.67

0.00001833

T4

0.015 mg/ml

200000

4

3

4

3.67

0.00001833

PC

400 µg/ml

200000

88

76

79

81.00

0.00040500

 Key: NC = Negative Control, VC = Vehicle Control, PC = Positive Control (Ethylmethanesulfonate), T4-T1= Test Item concentration from higher to lower, R = Replicate, CE = Cloning Efficiency, RS = Relative Survival, mg = milligram, µg =microgram, ml = milliliter.

 

 

Appendix 10: Cloning Efficiency(Selective medium)Phase I: Presence of metabolic activation

 

Dose level

Selective medium

 

Concentration

No. of cells

 seeded

No. of colonies

Mean No. of colonies

CE

R1

R2

R3

NC

Distilled water

200000

3

4

3

3.33

0.00001667

VC

Dimethylformamide

200000

4

2

4

3.33

0.00001667

T1

0.001875 mg/ml

200000

3

5

3

3.67

0.00001833

T2

0.00375 mg/ml

200000

4

4

2

3.33

0.00001667

T3

0.0075 mg/ml

200000

3

3

4

3.33

0.00001667

T4

0.015 mg/ml

200000

3

5

3

3.67

0.00001833

PC

30 µg/ml

200000

82

80

85

82.33

0.00041167

 

Key: NC = Negative Control, VC = Vehicle Control, PC = Positive Control (Benzo[a]pyrene), T4-T1= Test Item concentration from higher to lower, R = Replicate, CE = Cloning Efficiency, RS = Relative Survival, mg = milligram, µg =microgram, ml = milliliter.


Appendix11: Mutation Frequency: Absence of metabolic activation

 

Dose level

Absence of metabolic activation

Concentration

Mutation Frequency

MF x 10-6

NC

Distilled water

0.00000774

7.74

VC

Dimethylformamide

0.00000873

8.73

T1

0.001875 mg/ml

0.00000968

9.68

T2

0.00375 mg/ml

0.00000907

9.07

T3

0.0075 mg/ml

0.00001017

10.17

T4

0.015 mg/ml

0.00001052

10.52

PC

400 µg/ml*

0.00023456

234.56

 

Dose level

Presence of metabolic activation

Concentration

Mutation Frequency

MF x 10-6

NC

Distilled water

0.00000763

7.63

VC

Dimethylformamide

0.00000800

8.00

T1

0.001875 mg/ml

0.00000968

9.68

T2

0.00375 mg/ml

0.00000911

9.11

T3

0.0075 mg/ml

0.00000956

9.56

T4

0.015 mg/ml

0.00001058

10.58

PC

30 µg/ml*

0.00023750

237.50

Key: NC = Negative Control, VC = Vehicle Control, PC = Positive Control (Absence of metabolic activation- Ethylmethanesulfonate, Presence of metabolic activation- Benzo[a]pyrene), T4-T1= Test item concentration from higher to lower, MF = Mutation Frequency, mg = milligram, µg =microgram, ml = milliliter, * = Stastically significant increse in mutation frequency.

Conclusions:
The registered substance, α,α-bis[4-(dimethylamino)phenyl]-4-(phenylamino)naphthalene-1-methanol [CAS No.: 6786-83-0] was tested non-mutagenic (negative) in mammalian cells both in the presence and absence of S9 metabolic activation. The test was performed according to OECD TG 476 and in compliance with GLP.
Executive summary:

The potential of the registered substance, α,α-bis[4-(dimethylamino)phenyl]-4-(phenylamino)naphthalene-1-methanol [CAS No.: 6786-83-0] to induce gene mutation at the hypoxanthine-guanine phosphoribosyltransferase (Hprt) locus was tested in the presence and absence of an exogenous metabolic activation system using cultured Chinese Hamster Ovary (CHO) cells. The study was performed as per OECD Test Guideline No. 476 (Adopted: 29 July 2016). Cofactor-supplemented S9 liver microsomal fraction was used as an exogenous metabolic activation system. Dimethylformamide was selected as a solvent for the test substance during the experiment. Test concentrations were determined based on a preliminary cytotoxicity test. In the initial cytotoxicity test, the CHO cells were exposed to test item concentrations of 0 (VC), 0 (NC), 0.03125, 0.0625, 0.125, 0.25 and 0.5 mg/ml in culture medium, both in the presence and absence of a metabolic activation system (1 % v/v S9 mix). Cytotoxicity was determined by the Relative survival (RS[RS is cloning efficiency (CE) of cells plated immediately after treatment adjusted by any loss of cells during treatment as compared with cloning efficiency in vehicle control]) values. Complete cytotoxicity was observed at tested concentrations of 0.03125-0.5 mg/ml both in the presence and absence of metabolic activation. Hence, the preliminary cytotoxicity test was repeated using the following concentrations: 0 (VC), 0 (NC), 0.001875, 0.00375, 0.0075, 0.015 and 0.03 mg/ml both in the presence and absence of a metabolic activation system (1 % v/v S9 mix). In the absence of metabolic activation, the RS values were 100% (negative control), 95.90% (vehicle control), 92.66% (at 0.001875 mg/ml), 74.95% (at 0.00375 mg/ml), 52.11% (at 0.0075 mg/ml), 18.73% (at 0.015 mg/ml) and 0.00% (at 0.03 mg/ml). In the presence of metabolic activation, the RS values were 100% (negative control), 96.13% (vehicle control), 89.99%, (at 0.001875 mg/ml), 66.90% (at 0.00375 mg/ml), 51.04% (at 0.0075 mg/ml), 17.45% (at 0.015 mg/ml) and 0.00% (at 0.03 mg/ml). Thus, complete cytotoxicity was observed at 0.03 mg/ml in the absence and presence of metabolic activation. Whereas at the reaming tested concentrations, limited cytotoxicity (>17% RS)was observed at 0.015 mg/ml, in the absence (RS: 18.73%) or presence (RS: 17.45%) of the S9 metabolic activation system. Hence, the gene mutation study was conducted with substance concentrations of 0.0 (NC), 0.0 (VC), 0.001875, 0.00375, 0.0075 and 0.015 mg/ml, both in the presence (1 % v/v S9 mix) and absence of metabolic activation system along with and positive controls (Ehtylmethanesulfonate: 400 µg/ml without S9mix;Benzo (a) pyrene: 30µg/ml, with S9 mix).Results:In the absence of metabolic activation, the RS values were 100% (negative control), 95.55% (vehicle control), 90.74% (at 0.001875 mg/ml), 73.01% (at 0.00375 mg/ml), 52.88% (at 0.0075 mg/ml), 18.78% (at 0.015 mg/ml) and 89.75% (at 400 µg/ml-positive control [Ehtylmethanesulfonate]). In the presence of metabolic activation, the RS values were 100% (negative control), 96.66% (vehicle control), 87.11% (at 0.001875 mg/ml), 67.73% (at 0.00375 mg/ml), 50.55% (at 0.0075 mg/ml) 18.51% (at 0.015 mg/ml) and 88.01% (30 µg/ml-positive control[Benzo[a]pyrene]). No significant increase in the mutation frequency (MF) either in absence(9.68x10-6, 9.07 x10-6, 10.17 x10-6and 10.52 x10-6at 0.001875 mg/ml, 0.00375 mg/ml, 0.0075 mg/ml and 0.015 mg/ml, respectively) or presence of metabolic activation (9.68 x10-6, 9.11x10-6, 9.56x10-6and 10.58x10-6at 0.001875 mg/ml, 0.00375 mg/ml, 0.0075 mg/ml and 0.015 mg/ml, respectively) was observed when compared to vehicle control (8.73 x10-6, 8.00 x10-6, absence and presence of S9, respectively). The positive controls (Ethylmethanesulfonate and Beno[a]pyrene in the absence and presence of metabolic activation, respectively) used in the study produced statistically significant increases in mutation frequency (234.56 x10-6, p<0.0001 [Ethylmethanesulfonate], 237.50 x10-6, p<0.0001 [Benzo(a)pyrene] in the absence and presence of metabolic activation, respectively).Conclusion:The Substance, α,α-bis[4-(dimethylamino)phenyl]-4-(phenylamino)naphthalene-1-methanol [CAS No.: 6786-83-0], did not induce gene mutation at the locus of hypoxanthine-guanine phosphoribosyltransferase (Hprt) in CHO cells up to 0.5 mg/ml, either in the presence or absence of S9 metabolic activation system.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Bacterial reverse mutation test:

The mutagenicity of the test substance, α,α-bis[4-(dimethylamino)phenyl]-4-(phenylamino)naphthalene-1-methanol (CAS Number: 6786-83-0; EC Number: 229-851-8) was tested according to OECD 471 using Salmonella typhimurium tester strains TA1537, TA1535, TA98, TA100 and TA102. The test was performed as two independent experiments according to the plate incorporation method (Trial I) and the preincubation method (Trial II), both in the presence and absence of rat liver microsomal activation (S9 mix). Concentrations used in the mutagenicity assay were selected based on a preliminary cytotoxicity assay. This preliminary cytotoxicity assay was performed using concentrations of 0.0000128, 0.000064, 0.00032, 0.0016, 0.008, 0.04, 0.2 and 1 mg/plate, with and without metabolic activation (10 % v/v S9 mix) using TA98 and TA100 strains. A slight reduction in the revertant counts and moderate inhibition of the background lawn was observed at 1mg/plate, and no reduction in the revertant count and/or inhibition in the background lawn was noted at concentrations from 0.0000128 to 0.2 mg/plate when compared to the vehicle control data. Based on the observations of the pre-test, the following doses were applied in the mutagenicity test: 0.0 (NC), 0.0 (VC), 0.0625, 0.125, 0.25, 0.5 and 1mg/plate, both in the presence and absence of metabolic activation, along with the negative, vehicle and positive controls. Trial I was performed according to the plate incorporation method. The test substance, together with the negative, vehicle and positive controls, were tested in triplicates. The Test Item doses were selected using a spacing factor of 2. There was slight precipitation, a slight reduction in revertant colony count and a moderate inhibition in the background lawn at 1 mg/plate. Furthermore, there was no increase in the number of revertant colonies and/or diminution of the background lawn at concentrations of 0.0625 - 0.5 mg/plate, neither in the presence nor the absence of metabolic activation compared to the vehicle control data. Trial II was performed to confirm the negative results observed in Trial I. Trial II was conducted according to the preincubation method; the substance was tested in all the tester strains in triplicates. There was slight precipitation, a slight reduction in revertant colony count and a moderate inhibition in the background lawn at 1 mg/plate. There was no increase in the number of revertant colonies and/or diminution of the background lawn at concentrations of 0.0625 - 0.5 mg/plate, neither in the presence nor in the absence of metabolic activation when compared to the vehicle control data. The numbers of revertant colonies of the vehicle (spontaneous revertant colonies) and positive controls (induced revertant colonies) of all the tester strains were within the range of historical data of the laboratory. The positive controls used in the study produced significant increases in the mean number of revertant colonies under both activated and non-activated conditions in all tester strains compared to the vehicle control data confirming the validity of the mutagenicity test. Based on the results of this study, it is concluded that(4-anilino-1-naphthyl){bis[4-(dimethylamino)phenyl]}methanol (CAS No. 6786-83-0) is non-mutagenic as it does not induce gene mutations (point and frameshift) in the histidine operon by base-pair changes or frameshifts, in the presence or the absence of metabolic activation system, in any of the five tester strains of Salmonella typhimurium (TA1537, TA1535, TA98, TA100 and TA102).

In vitro mammalian chromosome aberration test:

The potential of (4-anilino-1-naphthyl){bis[4-(dimethylamino)phenyl]}methanol (CAS No. 6786-83-0) to induce structural chromosomal aberration was tested according to OECD TG 473 with and without metabolic activation in cultured Chinese Hamster Ovary (CHO) cells. Cofactor-supplemented liver S9 microsomal fraction was used as an exogenous metabolic activation. The S9 fraction was obtained from phenobarbitone and β-naphthoflavone-injected rats. The substance was insoluble in distilled water but was soluble in dimethyl sulfoxide up to 10 mg/ml. Test concentrations were chosen based on a preliminary cytotoxicity experiment. In this pre-test, CHO cells were exposed to 0.0 (VC), 0.0 (NC), 0.00625, 0.0125, 0.025, 0.05 and 0.1 mg/ml for 4 hours in the presence (1 % v/v S9 mix) and absence of metabolic activation system. Excessive cytotoxicity (defined by a Relative Increase in Cell Count [RICC] of <40% of the concurrent vehicle control data) was observed for the Test Item concentrations at ≥0.0125 mg/ml, both in the presence and absence of metabolic activation. RICC decreased by 55±5% compared to vehicle control at 0.00625 mg/ml both in the presence and absence of metabolic activation. Hence, Phase I (short term[4hrs]exposure in the absence of metabolic activation), Phase II (short term[4 hrs]exposure in the presence of metabolic activation) and Phase III (continuous[24 hrs]exposure in the absence of metabolic activation) were conducted with the Test Item at the concentrations of 0.0015625, 0.003125 and 0.00625 mg/ml, along with vehicle (DMSO), negative (Distilled water) and concurrent positive (Methyl methanesulfonate, 20µg/ml, without S9 mix; Benzo (a) pyrene, 30µg/ml with S9 mix)controls. At least 300 well-spread metaphases per concentration (single culture) were analyzed using 100x magnification for the incidence of structural aberrations. Breaks (chromatid and chromosomal), gaps(chromatid and chromosomal), rings and fragments, and dicentric chromosomes were found as structural chromosome aberrations. Gaps were recorded and reported separately but not included in the total aberration frequency.Results:In the Phase I experiment, CHO cells were exposed to the substance, vehicle, negative and positive controls for 4 hours (short term exposure) in the absence of metabolic activation. The average RICC values were 98.85 % (vehicle control), 71.04 % (at 0.0015625 mg/ml), 61.00 % (at 0.003125 mg/ml) and 44.21 % (at 0.00625 mg/ml). No significant increase in mean percent aberrant cells was observed at 0.0015625 mg/ml (mean % aberrant cells: 0.67%), 0.003125 mg/ml (mean % aberrant cells: 0.67%), or at 0.00625 mg/ml (mean % aberrant cells: 0.33%) compared to the vehicle control data (mean % aberrant cells 0.33 %). In the Phase II experiment, cultures were exposed to the substance, vehicle, negative and positive controls for 4 hours (short term exposure) in the presence of metabolic activation (1 % v/v S9 mix). The average RICC values were 97.73 % (vehicle control), 74.42 % (at 0.0015625 mg/ml), 65.27 % (at 0.003125 mg/ml) and 45.04 % (at 0.00625 mg/ml). No significant increase in mean percent aberrant cells was observed at 0.0015625 mg/ml (mean % aberrant cells: 0.67%), 0.003125 mg/ml (mean % aberrant cells: 0.33%), or at 0.00625 mg/ml (mean % aberrant cells: 0.00%) compared to the vehicle control data (mean % aberrant cells: 0.00 %). In Phase III, cultures were exposed to the substance, vehicle, negative and positive control for 24 hours (continuous exposure) without metabolic activation. The average RICC values were 92.65 % (vehicle control), 73.76 % (at 0.0015625 mg/ml), 63.64 % (at 0.003125 mg/ml) and 48.76 % (at 0.00625 mg/ml). No significant increase in mean percent aberrant cells was observed at 0.0015625 mg/ml (mean % aberrant cells: 0.00%), 0.003125 mg/ml (mean % aberrant cells: 1.00%), or at 0.00625 mg/ml (mean % aberrant cells: 0.67%) compared to the vehicle control data (mean % aberrant cells 0.33 %). In all phases of the study, no significant reduction in RICC (cytotoxicity) and no increase in percent aberrant cells were observed in vehicle control (DMSO) either in the presence or absence of metabolic activation, when compared to the negative control (distilled water). The positive controls (-S9: methyl methanesulfonate, +S9: Benzo[a]pyrene) used in the study produced statistically significant increases in the percent of cells with structural chromosome aberrations (Phase I: 6.67%; p<0.0001, Phase II: 7.33%; p<0.0001, Phase III: 7.67%; p<0.0001) indicating the sensitivity of the test system to specific mutagens and confirmed that the test conditions were appropriate and that the metabolic activation system functioned properly.Conclusion:The registered substance, (4-anilino-1-naphthyl){bis[4-(dimethylamino)phenyl]}methanol (CAS No. 6786-83-0) did not induce chromosomal aberration up to 0.00625mg/ml, either in the presence or absence of S9 metabolic activation in CHO cells.

In vitro gene mutation test in mammalian cells:

The potential of the registered substance, α,α-bis[4-(dimethylamino)phenyl]-4-(phenylamino)naphthalene-1-methanol [CAS No.: 6786-83-0] to induce gene mutation at the hypoxanthine-guanine phosphoribosyltransferase (Hprt) locus was tested in the presence and absence of an exogenous metabolic activation system using cultured Chinese Hamster Ovary (CHO) cells. The study was performed as per OECD Test Guideline No. 476 (Adopted: 29 July 2016). Cofactor-supplemented S9 liver microsomal fraction was used as an exogenous metabolic activation system. Dimethylformamide was selected as a solvent for the test substance during the experiment. Test concentrations were determined based on a preliminary cytotoxicity test. In the initial cytotoxicity test, the CHO cells were exposed to test item concentrations of 0 (VC), 0 (NC), 0.03125, 0.0625, 0.125, 0.25 and 0.5 mg/ml in culture medium, both in the presence and absence of a metabolic activation system (1 % v/v S9 mix). Cytotoxicity was determined by the Relative survival (RS[RS is cloning efficiency (CE) of cells plated immediately after treatment adjusted by any loss of cells during treatment as compared with cloning efficiency in vehicle control]) values. Complete cytotoxicity was observed at tested concentrations of 0.03125-0.5 mg/ml both in the presence and absence of metabolic activation. Hence, the preliminary cytotoxicity test was repeated using the following concentrations: 0 (VC), 0 (NC), 0.001875, 0.00375, 0.0075, 0.015 and 0.03 mg/ml both in the presence and absence of a metabolic activation system (1 % v/v S9 mix). In the absence of metabolic activation, the RS values were 100% (negative control), 95.90% (vehicle control), 92.66% (at 0.001875 mg/ml), 74.95% (at 0.00375 mg/ml), 52.11% (at 0.0075 mg/ml), 18.73% (at 0.015 mg/ml) and 0.00% (at 0.03 mg/ml). In the presence of metabolic activation, the RS values were 100% (negative control), 96.13% (vehicle control), 89.99%, (at 0.001875 mg/ml), 66.90% (at 0.00375 mg/ml), 51.04% (at 0.0075 mg/ml), 17.45% (at 0.015 mg/ml) and 0.00% (at 0.03 mg/ml). Thus, complete cytotoxicity was observed at 0.03 mg/ml in the absence and presence of metabolic activation. Whereas at the reaming tested concentrations, limited cytotoxicity (>17% RS)was observed at 0.015 mg/ml, in the absence (RS: 18.73%) or presence (RS: 17.45%) of the S9 metabolic activation system. Hence, the gene mutation study was conducted with substance concentrations of 0.0 (NC), 0.0 (VC), 0.001875, 0.00375, 0.0075 and 0.015 mg/ml, both in the presence (1 % v/v S9 mix) and absence of metabolic activation system along with and positive controls (Ehtylmethanesulfonate: 400 µg/ml without S9mix;Benzo (a) pyrene: 30µg/ml, with S9 mix).Results:In the absence of metabolic activation, the RS values were 100% (negative control), 95.55% (vehicle control), 90.74% (at 0.001875 mg/ml), 73.01% (at 0.00375 mg/ml), 52.88% (at 0.0075 mg/ml), 18.78% (at 0.015 mg/ml) and 89.75% (at 400 µg/ml-positive control [Ehtylmethanesulfonate]). In the presence of metabolic activation, the RS values were 100% (negative control), 96.66% (vehicle control), 87.11% (at 0.001875 mg/ml), 67.73% (at 0.00375 mg/ml), 50.55% (at 0.0075 mg/ml) 18.51% (at 0.015 mg/ml) and 88.01% (30 µg/ml-positive control[Benzo[a]pyrene]). No significant increase in the mutation frequency (MF) either in absence(9.68x10-6, 9.07 x10-6, 10.17 x10-6and 10.52 x10-6at 0.001875 mg/ml, 0.00375 mg/ml, 0.0075 mg/ml and 0.015 mg/ml, respectively) or presence of metabolic activation (9.68 x10-6, 9.11x10-6, 9.56x10-6and 10.58x10-6at 0.001875 mg/ml, 0.00375 mg/ml, 0.0075 mg/ml and 0.015 mg/ml, respectively) was observed when compared to vehicle control (8.73 x10-6, 8.00 x10-6, absence and presence of S9, respectively). The positive controls (Ethylmethanesulfonate and Beno[a]pyrene in the absence and presence of metabolic activation, respectively) used in the study produced statistically significant increases in mutation frequency (234.56 x10-6, p<0.0001 [Ethylmethanesulfonate], 237.50 x10-6, p<0.0001 [Benzo(a)pyrene] in the absence and presence of metabolic activation, respectively).Conclusion:The Substance, α,α-bis[4-(dimethylamino)phenyl]-4-(phenylamino)naphthalene-1-methanol [CAS No.: 6786-83-0], did not induce gene mutation at the locus of hypoxanthine-guanine phosphoribosyltransferase (Hprt) in CHO cells up to 0.5 mg/ml, either in the presence or absence of S9 metabolic activation system.

Justification for classification or non-classification

The registered substance, α,α-bis[4-(dimethylamino)phenyl]-4-(phenylamino)naphthalene-1-methanol [CAS No.: 6786-83-0], did not induce gene mutation by base-pair exchange and/or frameshift in five Salmonella Typhimurium tester strains (TA98, TA100, TA1535, TA1537 and TA102) in the presence and absence of liver S9 microsomal activation. The substance was tested non-clastogenic in mammalian cells as the exposure of Chinese Hamster Ovary (CHO) cells to the substance did not raise the percent of cells with structural chromosomal aberrations in either the presence or the absence of S9 metabolic activation. Additionally, the substance tested non-mutagenic (negative) in cultured mammalian cells as it did not produce point mutation at the locus of hypoxanthine-guanine phosphoribosyltransferase (Hprt) in CHO cells either in the presence or absence of S9 metabolic activation. Hence, the registered substance, α,α-bis[4-(dimethylamino)phenyl]-4-(phenylamino)naphthalene-1-methanol [CAS No.: 6786-83 -0] is classified as Non-Classified for Germ cell mutagenicity according to the Regulation (EC) No 1272/2008 on classification, labelling and packaging (CLP) of substances and mixtures.