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Administrative data

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Clearly negative in vitro studies - both with and without metabolic activation.


Gene mutation (Bacterial reverse mutation assay / Ames test, in vitro) - (GLP, OECD TG 471, EU method B13/14) : S. typhimurium TA 100, TA98, TA1535, TA1537 and E. coli WP2uvrA: negative with and without metabolic activation, 9 concentrations (0, 1.5, 5, 15, 50, 150, 500, 1500 and 5000 µg/plate)

Mouse lymphoma assay (in vitro) - (GLP, OECD 476, EU Method B17): negative with and without metabolic activation (TK +/- locus in mouse lymphoma L5178Y cells), 7 concentrations (0, 156.25, 312.5, 625, 1250, 2500 and 5000 μg/mL)

Chromosome aberration test (human lymphocytes, in vitro) - (GLP, OECD 473) : negative with and without metabolic activation, 8 concentrations (0, 0.09, 0.188, 0.375, 0.75, 1.25, 2.5 and 5 µg/ml).

Link to relevant study records

Referenceopen allclose all

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: DNA damage and/or repair
Type of information:
experimental study
Adequacy of study:
key study
Study period:
8.10.2014-6.11.2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study was performed according to the recommended Guidelines (OECD Guidelines for Testing of Chemicals No. 471 (1997) "Bacterial Reverse Mutation Test", Method B13/14 of Commission Regulation (EC) number 440/2008 of 30 May 2008, USA, EPA OCSPP harmonized guideline 870.5100 - Bacterial Reverse Mutation Test, Japanese Ministry of Economy, Trade and Industry, Japanese Ministry of Health, Labour and Welfare and Japanese Ministry of Agriculture, Forestry and Fisheries) and GLP.
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
1997
Deviations:
yes
Remarks:
No analysis was carried out to determine the homogeneity, concentration or stability of the test item formulation. This exception is considered not to affect the purpose or integrity of the study.
Qualifier:
according to guideline
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
Version / remarks:
(EC) 440/2008 of 30 May 2008
Deviations:
yes
Remarks:
No analysis was carried out to determine the homogeneity, concentration or stability of the test item formulation. This exception is considered not to affect the purpose or integrity of the study.
GLP compliance:
yes (incl. QA statement)
Remarks:
Certificate is included as an attachment to the study report.
Type of assay:
bacterial reverse mutation assay
Target gene:
Type of mutations indicated: frame shift mutations, base-pair substitutions
Species / strain / cell type:
E. coli WP2 uvr A
Additional strain / cell type characteristics:
other: Genotype: trp-; uvrA-:; Type of mutations indicated: base-pair substitution
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Additional strain / cell type characteristics:
other: Genotype: his C 3076; rfa-; uvrB-: /his D 3052; rfa-; uvrB-;R-factor: /his G 46; rfa-; uvrB-: /his G 46; rfa-; uvrB-;R-factor; Type of mutations indicated: frame shift mutations/base-pair substitutions
Metabolic activation:
with and without
Metabolic activation system:
S9
Test concentrations with justification for top dose:
The test item was tested using the following method. The maximum concentration was 5000 ug/plate (the maximum recommended dose level). Eight concentrations of the test item (1.5, 5, 15, 50, 150, 500, 1500 and 5000 ug/plate) were assayed in triplicate against each tester strain, using the direct plate incorporation method.
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: Sterile, distilled water
- Justification for choice of solvent/vehicle: The test item was insoluble in sterile distilled water, dimethyl sulphoxide, dimethyl formamide and acetonitrile at 50 mg/mL, acetone at 100 mg/mL and tetrahydrofuran at 200 mg/mL in solubility checks performed in–house. The test item formed the best doseable suspension in sterile distilled water, therefore, this solvent was selected as the vehicle.
Untreated negative controls:
yes
Remarks:
Negative (untreated) controls were used in parallel with the test item.
Negative solvent / vehicle controls:
yes
Remarks:
Culture with vehicle (sterile, distilled water)
True negative controls:
no
Positive controls:
yes
Positive control substance:
4-nitroquinoline-N-oxide
9-aminoacridine
N-ethyl-N-nitro-N-nitrosoguanidine
benzo(a)pyrene
other: 2-Aminoanthracene
Remarks:
2-Aminoanthracene and benzo(a)pyrene were used in the series of plates with S9-mix
Details on test system and experimental conditions:
Experiment 1.
DOSES: 1.5, 5, 15, 50, 150, 500, 1500 and 5000 ug/plate were assayed in triplicate against each tester strain, using the direct plate incorporation method.

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 48 h (incubation at 37 C± 3 C)

NUMBER OF REPLICATIONS: 3

OTHER EXAMINATIONS:
All of the plates were scored for the presence of revertant colonies using an automated colony counting system. The plates were viewed microscopically for evidence of thinning (toxicity).

Experiment 2.
As Experiment 1 was deemed negative, Experiment 2 was performed using the pre-incubation method in the presence and absence of metabolic activation.

METHOD OF APPLICATION: preincubation

DOSES: 50, 150, 500, 1500 and 5000 ug/plate were assayed in triplicate against each tester strain, using the pre-incubation method.

DURATION
- Exposure duration: 20 min preincubation (37 C± 3 C with shaking), 48 h incubation (37 C± 3 C)

NUMBER OF REPLICATIONS: 3

OTHER EXAMINATIONS:
All of the plates were scored for the presence of revertant colonies using an automated colony counting system. The plates were viewed microscopically for evidence of thinning (toxicity).
Evaluation criteria:
There are several criteria for determining a positive result. Any, one, or all of the following can be used to determine the overall result of the study:

1. A dose-related increase in mutant frequency over the dose range tested (De Serres and Shelby, 1979).
2. A reproducible increase at one or more concentrations.
3. Biological relevance against in-house historical control ranges.
4. Statistical analysis of data as determined by UKEMS (Mahon et al., 1989).
5. Fold increase greater than two times the concurrent solvent control for any tester strain (especially if accompanied by an out-of-historical range response (Cariello and Piegorsch, 1996)).

A test item will be considered non-mutagenic (negative) in the test system if the above criteria are not met.

Although most experiments will give clear positive or negative results, in some instances the data generated will prohibit making a definite judgment about test item activity. Results of this type will be reported as equivocal.
Statistics:
The individual plate counts, the mean number of revertant colonies and the standard deviations were determined for the test item, positive and vehicle controls, both with and without metabolic activation.

The analyses were appropriate to determine the mutagenicity of the test item.

A history profile of vehicle, untreated and positive control values (reference items) are also presented.
Species / strain:
other: S. typhimurium strains TA1535, TA1537, TA98 and TA100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not determined
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not determined
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Water solubility: Insoluble in water. However, the test item formed the best doseable suspension in sterile distilled water, therefore, this solvent was selected as the vehicle.
- Precipitation: test item precipitate (greasy in appearance) was observed at and above 1500 ug/plate. This observation did not prevent the scoring of revertant colonies.

COMPARISON WITH HISTORICAL CONTROL DATA: See table 1
Remarks on result:
other: all strains tested

Table 1. History Profile of Vehicle and Positive Control Values

COMBINED VEHICLE AND UNTREATED CONTROL VALUES 2012
Strain S9-Mix TA100 TA1535 TA102 WP2uvrA TA98 TA1537 WP2uvrA pKM101 WP2pKM101
-S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9
Mean 97 96 20 14 274 313 32 37 22 25 12 13 124 153 95 123
SD 16.9 17.9 5.1 3.3 26.8 38.2 8.0 7.8 5.8 6.7 2.7 2.8 27.0 37.4 15.9 18.0
Min 62 63 9 9 209 255 14 15 11 5 4 3 79 78 66 89
Max 162 169 39 33 321 355 58 59 48 42 24 25 216 242 161 168
Values† 780 560 561 347 20 8 668 479 898 369 880 347 64 43 56 34
POSITIVE CONTROL VALUES 2012
Strain S9-Mix TA100 TA1535 TA102 WP2uvrA TA98 TA1537 WP2uvrA pKM101 WP2pKM101
-S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9
Mean 546 1097 406 287 1033 840 734 330 167 204 778 245 764 1420 2027 633
SD 223.5 394.5 378.8 143.3 413.1 248.9 223.3 139.8 54.2 76.8 444.9 90.8 393.4 357.5 522.9 308.7
Min 266 268 85 108 541 418 256 120 81 85 146 98 158 714 1065 261
Max 3151 3241 4157 1335 1961 1284 1661 1409 420 677 3110 622 1910 2070 3071 1700
Values† 221 233 212 226 13 13 189 188 345 233 340 226 20 22 21 36
COMBINED VEHICLE AND UNTREATED CONTROL VALUES 2013
Strain S9-Mix TA100 TA1535 TA102 WP2uvrA TA98 TA1537 WP2uvrA pKM101 WP2pKM101
-S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9
Total Plates 843 855 1612 798 12 6 1542 765 1655 876 1646 807 42 36 42 36
Min 68 63 9 8 191 266 15 13 10 12 5 5 110 112 105 108
Max 147 153 37 29 292 292 47 54 42 43 26 23 162 181 154 162
Mean 103 101 20 15 255 279 28 33 22 26 11 13 138 152 124 137
SD 14.4 15.6 4.4 3.5 47.3 18.4 6.6 7.1 5.0 5.1 3.1 3.5 14.4 22.2 15.4 17.1
POSITIVE CONTROL VALUES 2013
Strain S9-Mix TA100 TA1535 TA102 WP2uvrA TA98 TA1537 WP2uvrA pKM101 WP2pKM101
-S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9 -S9 +S9
Total Plates 849 861 810 795 6 6 765 762 828 849 825 804 21 30 21 30
Min 240 349 91 103 668 673 129 101 102 84 113 86 501 840 302 385
Max 1429 3117 3750 1153 1016 694 1275 733 783 669 2161 1238 1124 2391 2889 1198
Mean 543 1211 644 250 842 684 611 320 207 226 813 286 698 1359 1288 665
SD 192.1 509.3 685.5 98.9 246.1 14.elo 256.3 120.9 76.9 92.6 384.2 127.7 263.1 441.9 894.7 305.7

SD Standard deviation

Min Minimum value

Max Maximum value

† Number of mean values used to create dataset

Table 2 Spontaneous Mutation Rates (Concurrent Negative Controls).

Experiment 1

Number of revertants (mean number of colonies per plate)
Base-pair substitution type Frameshift type
TA100 TA1535 WP2uvrA TA98 TA1537
71 (81) 8 (15) 23 (26) 17 (14) 7 (10)
87 13 31 12 12
84 23 23 12 11

Experiment 2

Number of revertants (mean number of colonies per plate)
Base-pair substitution type Frameshift type
TA100 TA1535 WP2uvrA TA98 TA1537
103 (100) 21 (15) 11 (17) 11 (14) 11 (9)
95 11 23 12 7
103 12 17 20 9

Table 3. Test Results:

Experiment 1 – Without Metabolic Activation

Test Period From: 20 October 2014 To: 23 October 2014
S9-Mix
(-)
Dose Level Per Plate Number of revertants (mean) +/- SD
Base-pair substitution strains Frameshift strains
TA100 TA1535 WP2uvrA TA98 TA1537
Solvent
Control (WATER)
87 (80) 16 (13) 27 (23) 19 (20) 9 (11)
76 6.4+ 11 2.5 20 3.5 19 1.2 13 2.1
76   13   23   21   12  
1.5 ug 82 (82) 8 (11) 28 (26) 20 (24) 9 (10)
83 0.6 16 4.6 20 4.9 27 3.5 13 2.6
82   8   29   24   8  
5 ug 75 (73) 12 (15) 28 (27) 17 (15) 5 (7)
79 7.2 19 3.8 36 9.5 12 2.5 5 4.0
65   13 17   15 12  
15 ug 107 (91) 12 (10)  24 (23) 15 (15) 8 (7)
82 14.2 11 2.6 29 6.0 17 2.5 8 1.7
83   7   17   12   5  
50 ug 84 (76) 20 (14) 19 (21) 12 (15) 11 (10)
60 13.6 15 6.0 12 10.7 12 5.2 12 2.6
83   8 33   21 7  
150 ug 83 (86) 15 (12) 11 (16) 13 (16) 9 (10)
91 4.6 15 4.6 21 5.0 24 7.0 5 5.0
83   7   17   11   15  
500 ug 86 (83) 12 (14) 12 (20) 13 (15) 5 (11)
72 9.5 20 5.7 28 8.0 15 1.5 16 5.6
90   9 20   16 12  
1500 ug 76P (80) 12P (12) 21P (17) 11P (16) 11P (12)
83P 3.5 13P 1.0 15P 3.5 20P 4.6 16P 4.0
80P   11P   15P   17P   8P  
5000 ug 100P (89) 11P (11) 15P (21) 11P (10) 15P (10)
92P 12.2 8P 3.5 21P 6.5 8P 1.7 7P 4.2
76P   15P 28P   11P 9P  
Positive controls S9-Mix (-) Name Dose Level No. of Revertants ENNG ENNG ENNG 4NQO 9AA
3 ug 5 ug 2 ug 0.2 ug 80 ug
648 (632) 859 (852) 1121 (1162) 158 (178) 970 (1186)
539 85.7 841 9.9 1276 100.4 219 35.8 1056 302.1
708   857   1088   156   1531  

ENNG N-ethyl-N'-nitro-N-nitrosoguanidine

4NQO 4-Nitroquinoline-1-oxide

9AA 9-Aminoacridine

P Test item precipitate

+ Standard deviation

Experiment 1 – With Metabolic Activation

Test Period From: 20 October 2014 To: 23 October 2014
S9-Mix
(+)
Dose Level Per Plate Number of revertants (mean) +/- SD
Base-pair substitution strains Frameshift strains
TA100 TA1535 WP2uvrA TA98 TA1537
Solvent
Control (WATER)
98 (87) 17 (13) 21 (19) 16 (20) 19 (12)
79 10.0+ 12 3.2 21 2.9 24 4.0 9 5.8
83   11   16   21   9  
1.5 ug 74 (74) 9 (11) 20 (24) 16 (19) 11 (13)
76 2.0 9 3.5 24 3.5 29 9.3 15 2.1
72   15   27   11   12  
5 ug 79 (77) 11 (15) 24 (21) 16 (16) 15 (10)
86 10.7 11 7.5 20 2.6 16 0.6 7 4.2
65   24 19   15 9  
15 ug 71 (78) 11 (12)  24 (23) 19 (20) 16 (14)
72 11.3 9 3.6 25 2.6 23 2.3 16 4.0
91   16   20   19   9  
50 ug 95 (93) 12 (13) 17 (19) 12 (18) 19 (12)
82 10.1 11 2.1 20 1.5 17 6.6 11 6.1
102   15 19   25 7  
150 ug 69 (81) 12 (12) 29 (21) 15 (21) 15 (15)
107 22.2 11 0.6 13 8.0 23 4.9 19 3.5
68   12   20   24   12  
500 ug 79 (91) 13 (10) 24 (23) 21 (24) 9 (11)
83 20.8 7 3.1 19 3.2 27 3.0 15 3.8
115   11 25   24 8  
1500 ug 98P (82) 16P (14) 25P (23 17P (19) 20P (16)
64P 17.0 13P 2.1 23P 2.5 17P 3.5 16P 4.5
83P   12P   20p   23P   11P  
5000 ug 86P (82) 7P (8) 19P (16) 15P (17) 8P (10)
76P 53. 8P 1.0 13P 3.1 25P 6.8 5P 5.7
84P   9P 15P   12P 16P  
Positive controls S9-Mix
(+)
Name Dose Level No. of Revertants 2AA 2AA 2AA BP 2AA
3 ug 5 ug 2 ug 5 ug 80 ug
1431 (1544) 188 (216) 237 (237) 275 (261) 674 (677)
1612 98.5 211 30.8 237 0.0 257 12.5 659 19.7
1589   249   237   251   698  

BP Benzo(a)pyrene

2AA 2-Aminoanthracene

P Test item precipitate

+ Standard deviation

Experiment 2 – Without Metabolic Activation

Test Period From: 3 November 2014 To: 6 November 2014
S9-Mix
(-)
Dose Level Per Plate Number of revertants (mean) +/- SD
Base-pair substitution strains Frameshift strains
TA100 TA1535 WP2uvrA TA98 TA1537
Solvent
Control (WATER)
92 (101) 11 (13) 25 (21) 12 (15) 9 (11)
100 9.0+ 11 3.5 23 5.3 15 2.5 11 2.0
110   17   15   17   13  
50 ug 91 (93) 9 (13) 13 (14) 16 (13) 9 (12)
84 9.6 16 3.8 17 2.3 12 2.3 15 3.1
103   15   13   12   13  
150 ug 106 (100) 9 (9) 13 (14) 24 (16) 9 (11)
87 11.3 9 0 11 4.2 11 7.8 8 4.9
107   9 19   12 17  
500 ug 104 (103) 15 (13)  11 (15) 15 (16) 16 (9)
96 7.0 12 2.1 13 4.7 9 3.8 3 6.6
110   11   20   16   8  
1500 ug 107P (92) 13P (12) 20P (17) 11P (10) 9P (10)
88P 13.1 15P 3.1 20P 5.2 9P 1.2 8P 2.1
82P   9P 11P   11P 12P  
5000 ug 79P (80) 13P (16) 13P (16) 16P (15) 7P (8)
87P 6.1 20P 3.6 19P 3.0 11P 4.0 5P 4.2
75P   15P   16P   19P   13P  
Positive controls S9-Mix
(-)
Name Dose Level No. of Revertants ENNG ENNG ENNG 4NQO 9AA
3 ug 5 ug 2 ug 0.2 ug 80 ug
763 (660) 186 (171) 664 (644) 198 (211) 517 (441)
664 105.1 114 51.6 631 17.8 227 14.7 429 71.2
553   214   636   208   376  

ENNG N-ethyl-N'-nitro-N-nitrosoguanidine

4NQO 4-Nitroquinoline-1-oxide

9AA 9-Aminoacridine

P Test item precipitate

+ Standard deviation

Experiment 2 – With Metabolic Activation

Test Period From: 3 November 2014 To: 6 November 2014
S9-Mix
(+)
Dose Level Per Plate Number of revertants (mean) +/- SD
Base-pair substitution strains Frameshift strains
TA100 TA1535 WP2uvrA TA98 TA1537
Solvent
Control (WATER)
107 (103) 9 (11) 20 (21) 23 (20) 8 (9)
96 6.4+ 12 1.7 17 4.0 16 3.5 11 1.7
107   12   25   20   8  
50 ug 118 (111) 11 (13) 17 (18) 20 (18) 13 (10)
108 6.4 12 2.1 15 3.1 16 2.1 5 4.4
106   15   21   17   12  
150 ug 100 (93) 19 (14) 19 (20) 32 (21) 8 (9)
100 12.1 12 4.4 24 4.0 17 3.8 12 2.3
79   11 16   24 8  
500 ug 116 (104) 9 (10) 25 (23) 25 (20) 19 (15)
92 12.1 9 1.2 19 3.2 27 10.4 15 3.5
104   11   24   8   12  
1500 ug 86P (93) 11P (11) 25P (20) 23P (18) 8P (9)
88P 12.0 12P 0.6 21P 5.0 13P 5.0 7P 2.6
104P   11P 15P   19P 12P  
5000 ug 100P (102) 11P (11) 23P (20) 21P (20) 9P (14)
94P 8.6 11P 0.6 25P 6.4 23P 3.1 13P 5.0
111P   12P   13P   17P   19P  
Positive controls S9-Mix
(+)
Name Dose Level No. of Revertants 2AA 2AA 2AA BP 2AA
1 ug 2 ug 10 ug 5 ug 2 ug
3626 (3505) 261 (279) 178 (187) 106 (123) 535 (562)
3417 108.8 287 15.9 178 16.2 126 16.2 516 64.5
3473   290   206   138   636  

BP Benzo(a)pyrene

2AA 2-Aminoanthracene

P Test item precipitate

+ Standard deviation

Conclusions:
Interpretation of results: negative. Not classified according to the CLP Regulation based on the Reverse Mutation Assay 'Ames Test' using Salmonella
typhimurium and Escherichia coli. The test item was considered to be non-mutagenic under the conditions of the test.
Executive summary:

Salmonella typhimurium strains TA1535, TA1537, TA98 and TA100 and Escherichia coli strain WP2uvrA were treated with suspensions of the test item using both the Ames plate incorporation and pre-incubation methods at up to eight dose levels, in triplicate, both with and without the addition of a rat liver homogenate metabolizing system (10% liver S9 in standard co-factors). The dose range for Experiment 1 was predetermined and was 1.5 to 5000 ug/plate. The experiment was repeated on a separate day (pre-incubation method) using fresh cultures of the bacterial strains and fresh test item formulations. The dose range was amended following the results of Experiment 1 and was 50 to 5000 μg/plate.

The vehicle (sterile distilled water) control plates gave counts of revertant colonies within the normal range. All of the positive control chemicals used in the test induced marked increases in the frequency of revertant colonies, both with or without metabolic activation. Thus, the sensitivity of the assay and the efficacy of the S9 -mix were validated.

The maximum dose level of the test item in the first experiment was selected as the maximum recommended dose level of 5000 μg/plate. There was no visible reduction in the growth of the bacterial background lawn at any dose level, either in the presence or absence of metabolic activation (S9-mix), in the first mutation test (plate incorporation method) and consequently the same maximum dose level was used in the second mutation test. Similarly, there was no visible reduction in the growth of the bacterial background lawn at any dose level, either in the presence or absence of S9-mix, in the second mutation test (pre-incubation method). A test item precipitate (greasy in appearance) was observed at and above 1500 g/plate, this observation did not prevent the scoring of revertant colonies.

There were no significant increases in the frequency of revertant colonies recorded for any of the bacterial strains, with any dose of the test item, either with or without S9-mix in Experiment 1 (plate incorporation method). Similarly, no significant increases in the frequency of revertant

colonies were recorded for any of the bacterial strains, with any dose of the test item, either with or without S9-mix in Experiment 2 (pre-incubation method).

The substance was considered to be non-mutagenic under the conditions of the test.

Endpoint:
in vitro gene mutation study in mammalian cells
Remarks:
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
31.3.2015-9.6.2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study was performed following the recommended Guidelines (OECD Guidelines for Testing of Chemicals No.476 "In Vitro Mammalian Cell Gene Mutation Test" and Method B17 of Commission Regulation (EC) No. 440/2008) and GLP.
Qualifier:
according to guideline
Guideline:
EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)
Version / remarks:
(EC) No. 440/2008 of 30 May 2008
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)
Version / remarks:
Adopted 21 July 1997
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
Cerificate is included in the study report as an attachment
Type of assay:
other: In vitro gene mutation study in mammalian cells
Target gene:
Thymidine kinase, TK +/-, locus of the L5178Y mouse lymphoma cell line
Species / strain / cell type:
mouse lymphoma L5178Y cells
Details on mammalian cell type (if applicable):
CELLS USED
- Source of cells: The L5178Y TK+/- 3.7.2c mouse lymphoma cell line was obtained from Dr. J. Cole of the MRC Cell Mutation Unit at the University of Sussex, Brighton, UK. The cells were originally obtained from Dr. D. Clive of Burroughs Wellcome (USA) in October 1978 and were frozen in liquid nitrogen at that time.
- Suitability of cells: The thymidine kinase heterozygote system, TK +/- to TK -/-, was described by Clive et al., (1972) and is based upon the L5178Y mouse lymphoma cell line established by Fischer (1958). This system has been extensively validated (Clive et al., 1979; Amacher et al., 1980; Jotz and Mitchell, 1981).
- Cell cycle length, doubling time or proliferation index: The cells have a generation time of approximately 12 hours and were subcultured accordingly.

MEDIA USED
- Type and identity of media: The stocks of cells are routinely cultured in RPMI 1640 medium with Glutamax-1 and HEPES buffer (20 mM) supplemented with Penicillin (100 units/mL), Streptomycin (100 μg/mL), Sodium pyruvate (1 mM), Amphotericin B (2.5 μg/mL) and 10% donor horse serum (giving R10 media) at 37 °C with 5% CO2 in air.
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically "cleansed" against high spontaneous background: yes

Additional strain / cell type characteristics:
other: L5178Y TK +/- 3.7.2c mouse lymphoma cells (heterozygous at the thymidine kinase locus)
Metabolic activation:
with and without
Metabolic activation system:
S9
Test concentrations with justification for top dose:
The molecular weight of the test item was 843, therefore the maximum proposed dose level was 5000 μg/mL, the maximum recommended dose.

Experiment 1 (Concentration of test item (μg/mL) plated for mutant frequency): 156.25, 312.5, 625, 1250, 2500, 5000

Experiment 2 (Concentration of test item (μg/mL) plated for mutant frequency): 156.25, 312.5, 625, 1250, 2500, 5000
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: R0 (RPMI 1640 without serum)
- Solvent (R0 medium) treatment groups were used as the vehicle controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
R0
True negative controls:
no
Positive controls:
yes
Positive control substance:
cyclophosphamide
ethylmethanesulphonate
Details on test system and experimental conditions:
METHOD OF APPLICATION: in medium (microtitre plates)
- Cell density at the beginning (if applicable): 1x 10^6 cells/mL and 0.3 x 10^6 cells/mL

DURATION
- Exposure duration: 4 h or 24 h
- Expression time (cells in growth medium): 2 days
- Selection time (if incubation with a selection agent): 10 - 14 days

SELECTION AGENT (mutation assays): trifluorothymidine

NUMBER OF REPLICATIONS: 2

NUMBER OF CELLS EVALUATED: mutant frequency: 2000 cells/well; viability: 2 cells/well

Rationale for test conditions:
A preliminary toxicity test was performed on the cell cultures. The dose range used in the preliminary toxicity test was 19.53 to 5000 μg/mL for all three of the exposure groups. During the course of the study dose selection for the mutagenicity experiments was made using data from the preliminary toxicity test in an attempt to obtain the desired levels of toxicity.

Results from the preliminary toxicity test were used to set the test item dose levels for the mutagenicity experiments. Maximum dose levels were selected using the following criteria:
i) Maximum recommended dose level, 5000 μg/mL or 10 mM.
ii) The presence of excessive precipitate where no test item-induced toxicity was observed.
iii) Test item-induced toxicity, where the maximum dose level used should produce 10 to 20% survival (the maximum level of toxicity required). This optimum upper level of toxicity was confirmed by an IWGT meeting in New Orleans, USA (Moore et al 2002).
Evaluation criteria:
For a test item to demonstrate a mutagenic response it must produce a statistically significant increase in the induced mutant frequency (IMF) over the concurrent vehicle mutant frequency value. Following discussions at an International Workshop on Genotoxicity Test Procedures in Plymouth, UK, 2002 (Moore et al 2003) it was felt that the IMF must exceed some value based on the global background MF for each method (agar or microwell). This Global Evaluation Factor (GEF) value was set following a further meeting of the International Workshop in Aberdeen, Scotland, 2003 (Moore et al 2006) at 126 x 10^-6 for the microwell method. Therefore, any test item dose level that has a mutation frequency value that is greater than the corresponding vehicle control by the GEF of 126 x 10^-6 and demonstrates a positive linear trend will be considered positive. However, if a test item produces a modest increase in mutant frequency, which only marginally exceeds the GEF value and is not reproducible or part of a dose-related response, then it may be considered to have no toxicological significance. Conversely, when a test item induces modest reproducible increases in the mutation frequencies that do not exceed the GEF value then scientific judgement will be applied. If the reproducible responses are significantly dose-related and include increases in the absolute numbers of mutant colonies then they may be considered to be toxicologically significant.
Statistics:
During the course of the study dose selection for the mutagenicity experiments was made using data from the preliminary toxicity test in an attempt to obtain the desired levels of toxicity. This optimum toxicity is approximately 20% survival (80% toxicity), but no less than 10% survival (90% toxicity). Relative Total Growth (RTG) values are usually the primary factor to designate the level of toxicity achieved by the test item for any individual dose level. However, under certain circumstances, %RSG values may also be taken into account when designating the level of toxicity achieved. Dose levels that have RTG survival values markedly less than 10% are excluded from any statistical analysis, as any response they give would be considered to have no biological or toxicological relevance.

The experimental data was analysed using a dedicated computer program, Mutant 240C by York Electronic Research, which follows the statistical guidelines recommended by the UKEMS (Robinson W D et al., 1989). Small significant increases designated by the UKEMS statistical package will be reviewed using
the evaluation criteria, and may be disregarded at the Study Director’s discretion.

Statistical analysis: Viability (%V), Suspension Growth, Relative Suspension Growth (%RSG), Relative Total Growth, 5-TFT resistant mutants, cell count.

The Reviewer considers the analyses used appropriate.
Species / strain:
mouse lymphoma L5178Y cells
Remarks:
L5178Y TK+/- 3.7.2c mouse lymphoma cell line
Metabolic activation:
with and without
Genotoxicity:
not determined
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Remarks:
The test item did not induce any toxicologically significant dose related increases in the mutant frequency at any of the dose levels (including the maximum recommended dose), in either the absence or presence of metabolic activation
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: No effect. There was no marked change in pH when the test item was dosed into media.
- Effects of osmolality: No effect. The osmolality did not increase by more than 50 mOsm when the test item was dosed into media.
- Water solubility: Test item not soluble in water
- Precipitation: Precipitate of the test item was observed at all of the dose levels.

RANGE-FINDING/SCREENING STUDIES:
For results of the Preliminary Cytotoxicity Test, see Table 1 in "Any other information on results incl. tables".

COMPARISON WITH HISTORICAL CONTROL DATA:
For historical control data, see Tables 15 and 16 in "Any other information on results incl. tables".

ADDITIONAL INFORMATION ON CYTOTOXICITY:
See Table 2 in "Any other information on results incl. tables".

Key to tables 1 to 16:

$ = Cell counts (x10^5 cells/mL). Set up on previous day to 2 x 10^5 cells/mL unless otherwise stated in parenthesis.

%RSG = Relative Suspension Growth

RTG = Relative Total Growth

%V = Viability Day 2

SG = Suspension growth

§ or # = Positive wells per tray, 96 wells plated unless otherwise stated in parenthesis

A,B = Replicate cultures

CP = Cyclophosphamide

EMS = Ethylmethanesulphonate

MF§ = 5-TFT resistant mutants/10^6 viable cells 2 days after treatment

NP = Not plated, surplus to requirements

Ø = Not plated for viability or 5-TFT resistance

Nv = Number of wells scored, viability plates

Yv = Number of wells without colonies, viability plates

Ym = Number of wells without colonies, mutation plates

Nm = Number of wells scored, mutation plates

Table 1. Preliminary Cytotoxicity Test

The dose range of the test item used in the preliminary toxicity test was 19.53 to 5000 μg/mL.

The results for the Relative Suspension Growth (%RSG) were as follows:

Dose (

ug/ml)
% RSG (-S9) 4-hour exposure % RSG (+S9) 4-hour exposure % RSG (-9) 24-hour exposure
0 100 100 100
19.53 99 103 117
39.06 98 102 118
78.13 97 102 115
156.25 98 97 118
312.5 78 47 93
625 61 58 79
1250 49 58 78
2500 50 49 57
5000 38 34 41

There was evidence of modest reductions in the Relative Suspension Growth (%RSG) of cells treated with the test item when compared to the concurrent vehicle controls in all three of the exposure groups. Precipitate of the test item was observed at all of the dose levels. Based on the %RSG values observed, the maximum dose level in the subsequent Mutagenicity Test was the maximum recommended dose of 5000 μg/mL.

Table 2. Mutagenicity Test - Summary of results

Experiment 1:

Treatment (μg/ml) 4-Hours-S9 Treatment
(μg/ml)
4-Hours+S9
%RSG RTG MF§ %RSG RTG MF§
0 100 1 105.50 0 100 1 127.25
39.06 Ø 96 39.06 Ø 99
78.13 Ø 101 78.13 Ø 102
156.25 94 1.01 103.45 156.25 107 1.06 112.66
312.5 89 0.97 111.70 312.5 93 0.98 106.08
625 84 0.89 116.36 625 72 1.01 88.03
1250 64 0.92 99.28 1250 69 1.04 89.16
2500 59 0.78 111.22 2500 60 0.73 106.06
5000 43 0.64 104.09 5000 44 0.60 124.27
Linear trend

NS

Linear trend

NS

EMS CP
400 68 0.53 971.56 1.5 71 0.50 1007.24

Experiment 2:

Treatment (μg/ml) 24-Hours-S9 Treatment
(μg/ml)
4-Hours+S9
%RSG RTG MF§ %RSG RTG MF§
0 100 1 144.22 0 100 1 125.12
39.06 Ø 91 39.06 Ø 98
78.13 Ø 95 78.13 Ø 94
156.25 93 1.10 100.89 156.25 102 1.09 133.06
312.5 105 1.09 123.21 312.5 88 1.09 96.46
625 41 0.83 116.68 625 61 0.71 113.45
1250 36 0.89 104.09 1250 59 0.90 98.16
2500 33 0.81 97.72 2500 54 0.91 89.16
5000 7 0.27 130.27 5000 42 0.62 117.62
Linear trend

NS

Linear trend

NS

EMS CP
150 34 0.36 1137.01 1.5 71 0.58 705.30

Table 3. Cell and 96-Well Plate Counts: Experiment 1 (-S9) 4-Hour Exposure

Treatment Cell counts $  Viability § Resistant mutants §
(μg/ml)     after day 2 after day 2
        2 cells/well  2000 cells/well 
    0 h 24 h 48 h                
0 A 9.64 6.05 7.59 73 76 81 75 16 15 13 13
  B 9.39 6.02 7.62 70 73 83 79 14 17 15 15
39.06 A 9.87 6.36 7.02 NP NP   NP NP  
  B 9.4 6.12 6.98 NP NP   NP NP  
78.13 A 9.69 6.39 7.46 NP NP   NP NP  
  B 9.77 6.27 6.88 NP NP   NP NP  
156.25 A 9.58 5.97 7.05 77 80   17 10  
  B 9.29 6.54 6.89 82 75   19 16  
312.5 A 9.71 6.02 6.78 80 75   18 18  
  B 9.89 6.07 6.38 83 77   15 16  
625 A 7.75 7.7 5.95 80 80   17 18  
  B 8.5 7.35 6 78 76   17 17  
1250 A 7.25 6.2 6.05 85 83   19 21  
  B 8.15 5.6 6.2 91 86   20 18  
2500 A 7.25 5.65 6.3 83 81   23 19  
  B 7.2 5.85 6.1 85 88   17 21  
5000 A 6 5.5 5.85 90 85   23 20  
  B 6 5.6 5.5 85 87   17 23  

Positive control EMS (μg/ml)

400 A 9.05 5.19 6.25 66 63 72 65    
  B 9.06 5.22 6.42 73 69     65 65    

Table 4. Statistical Analysis: Experiment 1 (-S9) 4-Hour Exposure

Treatment SG %RSG %V RTG MF§
(μg/ml)          
0 11.47 100 79.06 1 105.5
39.06 Ø 10.92 96    
78.13 Ø 11.35 101    
156.25 10.9 94 85.11 1.01 103.45
312.5 9.94 89 85.83 0.97 111.7
625 11.24 84 85.11 0.89 116.36
1250 9.03 64 114.35 0.92 99.28
2500 8.91 59 105.02 0.78 111.22
5000 7.87 43 116.99 0.64 104.09
Positive control EMS
Treatment SG %RSG %V RTG MF§
(μg/ml)          
400   8.24 68 61.16 0.53 971.56

Test for linear trend

Slope -3.73E-10
Variance 6.91E-18
b²/Sb 0.02

Table 5. Large and Small Colonies Analysis: Experiment 1 (-S9) 4-Hour Exposure

Treatment Viability # Small colonies # Large colonies #
(μg/ml) after day 2 after day 2 after day 2
0 A 73 76 81 75 7 8 7 9 9 7 6 4
  B 70 73 83 79 7 9 4 7 7 8 11 8
156.25 A 77 80   6 8   11 2  
  B 82 75   10 7   9 9  
312.5 A 80 75   8 8   10 10  
  B 83 77   6 7   9 9  
625 A 80 80   9 7   8 11  
  B 78 76   7 7   10 10  
1250 A 85 83   8 8   11 13  
  B 91 86   9 10   11 8  
2500 A 83 81   8 8   15 11  
  B 85 88   9 7   8 14  
5000 A 90 85   9 8   14 12  
  B 85 87   9 7   8 16  
400 EMS A 66 63   32 26   40 39  
  B 73 69     20 36     45 29    

Mutation frequencies

Treatment  Viable Small colonies  Large colonies Proportion small colony mutants
(μg/ml)
  Mutants   Mutants  
  Yv Nv Ym Nm MF§ Ym Nm MF§
0 158 768 710 768 49.7 708 768 51.4 0.49
156.25 70 384 353 384 49.5 353 384 49.5 0.5
312.5 69 384 355 384 45.7 346 384 60.7 0.43
625 70 384 354 384 47.8 345 384 62.9 0.43
1250 39 384 349 384 41.8 341 384 51.9 0.45
2500 47 384 352 384 41.4 336 384 63.6 0.4
5000 37 384 351 384 38.4 334 384 59.6 0.4
400 EMS 113 384 270 384 287.9 231 384 415.5 0.43

Table 6. Cell and 96-Well Plate Counts: Experiment 1 (+S9) 4-Hour Exposure

Treatment Cell counts $  Viability § Resistant mutants §
(μg/ml)     after day 2 after day 2
        2 cells/well  2000 cells/well 
    0 h 24 h 48 h                
0 A 9.53 6.3 7.58 70 79 82 78 17 18 23 19
  B 9.98 5.56 7.44 78 79 82 79 17 19 18 18
39.06 A 9.3 6.11 7.36 NP NP   NP NP  
  B 9.56 6.1 7.6 NP NP   NP NP  
78.13 A 8.95 6.59 7.89 NP NP   NP NP  
  B 9.12 5.83 7.83 NP NP   NP NP  
156.25 A 8.63 6.86 7.76 82 79   19 14  
  B 9.13 6.19 8.25 75 76   17 16  
312.5 A 8.5 6.38 7.78 84 81   16 17  
  B 8.54 5.68 7.91 79 77   18 16  
625 A 8.3 6.4 5.75 91 83   15 19  
  B 8.55 5.7 6.5 91 84   22 17  
1250 A 8.5 5.9 5.95 91 89   20 18  
  B 7.9 5.4 6.95 87 88   20 21  
2500 A 6.25 6.6 6.35 87 87   19 21  
  B 6.9 5.2 7.15 83 79   19 17  
5000 A 4.3 5.85 6.25 88 88   28 27  
  B 5.45 6.05 6.95 83 86     20 20    

Positive control CP (μg/ml)

1.5 A 9.74 4.25 7.45 63 64     62 67    
  B 9.75 4.86 6.37 74 68     66 75    

Table 7. Statistical Analysis: Experiment 1 (+S9) 4-Hour Exposure

Treatment   SG %RSG %V RTG MF§
(μg/ml)            
0 11.13 100 84.75 1 127.25
39.06 Ø 11.42 99    
78.13 Ø 12.2 102    
156.25 13.06 107 83.7 1.06 112.66
312.5 11.83 93 90.38 0.98 106.08
625 9.26 72 119.76 1.01 88.03
1250 9.11 69 129.17 1.04 89.16
2500 9.96 60 103.97 0.73 106.06
5000 9.82 44 114.35 0.6 124.27

Positive control EMS

Treatment SG %RSG %V RTG MF§
(μg/ml)          
1.5   7.87 71 60.29 0.5 1007.24

Test for linear trend

Slope 1.64E-09
Variance 8.88E-18
b²/Sb 0.302

Table 8. Large and Small Colonies Analysis: Experiment 1 (+S9) 4-Hour Exposure

Treatment Viability # Small colonies # Large colonies #
(μg/ml) after day 2 after day 2 after day 2
0 A 70 79 82 78 7 10 14 10 10 8 9 9
  B 78 79 82 79 7 10 8 8 10 9 10 10
156.25 A 82 79   9 8   10 6  
  B 75 76   9 9   8 7  
312.5 A 84 81   8 10   8 7  
  B 79 77   10 8   8 8  
625 A 91 83   11 10   4 9  
  B 91 84   9 9   13 8  
1250 A 91 89   7 10   13 8  
  B 87 88   13 10   7 11  
2500 A 87 87   9 12   10 9  
  B 83 79   11 7   8 10  
5000 A 88 88   12 13   16 14  
  B 83 86   12 9   8 11  
1.5 CP A 63 64   47 46   15 21  
  B 74 68     40 49     26 26    

Mutation frequencies

Treatment  Viable Small colonies  Large colonies Proportion small colony mutants
(μg/ml)
  Mutants   Mutants  
  Yv Nv Ym Nm MF§ Ym Nm MF§
0 141 768 694 768 59.8 693 768 60.6 0.5
156.25 72 384 349 384 57.1 353 384 50.3 0.53
312.5 63 384 348 384 54.5 353 384 46.6 0.54
625 35 384 345 384 44.7 350 384 38.7 0.53
1250 29 384 344 384 42.6 345 384 41.5 0.51
2500 48 384 345 384 51.5 347 384 48.7 0.51
5000 39 384 338 384 55.8 335 384 59.7 0.48
1.5 CP 115 384 202 384 532.8 296 384 215.9 0.67

Table 9. Cell and 96-Well Plate Counts: Experiment 2 (-S9) 24-Hour Exposure

Treatment Cell counts $  Viability § Resistant mutants §
(μg/ml)     after day 2 after day 2
        2 cells/well  2000 cells/well 
    0 h 24 h 48 h                
0 A 8.02 6.92 7.86 72 75 70 77 18 18 20 18
  B 9.22 6.32 7.52 70 77 75 70 20 19 17 14
39.06 A 7.85 8.13 6.36 NP NP   NP NP  
  B 8.44 7.38 6.98 NP NP   NP NP  
78.13 A 9.34 6.82 6.98 NP NP   NP NP  
  B 8 7.77 6.14 NP NP   NP NP  
156.25 A 9.19 6.58 7.03 81 81   15 20  
  B 8.6 5.68 7.41 79 78   14 14  
312.5 A 9.37 6.35 7.47 78 79   16 20  
  B 8.47 6.63 7.85 73 73   16 15  
625 A 6.05 4.95 9.45 82 85   22 16  
  B 4.9 7.8 6.8 84 75   19 19  
1250 A 4.3 7.9 6.55 85 84   22 17  
  B 6.9 4.9 7 90 88   22 22  
2500 A 6.35 5.85 5.7 89 86   21 21  
  B 5.45 5.45 7.15 88 87   18 21  
5000 A 3.8 5.2 4.9 86 78   22 24  
  B 3.15 3.75 4.85 88 92   27 25  

Positive control EMS (μg/ml)

150 A 5.66 5.76 6.12 69 54 79 73    
  B 6.19 6.4 5.85 67 60     56 60    

Table 10. Statistical Analysis: Experiment 2 (-S9) 24-Hour Exposure

Treatment SG %RSG %V RTG MF§
(μg/ml)          
0   73.14 100 71.99 1 144.22
39.06 Ø 70.22 91    
78.13 Ø 69.15 95    
156.25   65.61 93 88.81 1.1 100.89
312.5   73.91 105 77.81 1.09 123.21
625   47.26 41 94.51 0.83 116.68
1250   40.47 36 116.99 0.89 104.09
2500   35.7 33 121.21 0.81 97.72
5000   12.63 7 113.09 0.27 130.27
Positive control EMS
Treatment SG %RSG %V RTG MF§
(μg/ml)          
150   35.93 34 52.64 0.36 1137.01

Test for linear trend

Slope -7.94E-10
Variance 9.33E-18
b²/Sb 0.068

Table 11. Large and Small Colonies Analysis: Experiment 2 (-S9) 24-Hour Exposure

Treatment Viability # Small colonies # Large colonies #
(μg/ml) after day 2 after day 2 after day 2
0 A 72 75 70 77 2 7 12 9 16 11 8 9
  B 70 77 75 70 7 8 8 7 13 11 9 7
156.25 A 81 81   6 9   9 11  
  B 79 78   7 8   7 6  
312.5 A 78 79   6 9   10 11  
  B 73 73   9 8   7 7  
625 A 82 85   7 6   15 10  
  B 84 75   10 4   9 15  
1250 A 85 84   7 7   15 10  
  B 90 88   11 13   11 9  
2500 A 89 86   9 10   12 11  
  B 88 87   9 12   9 9  
5000 A 86 78   9 10   13 14  
  B 88 92   11 10   16 15  
150 EMS A 69 54   34 34   45 39  
  B 67 60     20 29     36 31    

Mutation frequencies

Treatment  Viable Small colonies  Large colonies Proportion small colony mutants
(μg/ml)
  Mutants   Mutants  
  Yv Nv Ym Nm MF§ Ym Nm MF§
0 182 768 708 768 56.5 684 768 80.5 0.42
156.25 65 384 354 384 45.8 351 384 50.6 0.48
312.5 81 384 352 384 55.9 349 384 61.4 0.48
625 58 384 357 384 38.6 335 384 72.2 0.36
1250 37 384 346 384 44.5 339 384 53.3 0.46
2500 34 384 344 384 45.4 343 384 46.6 0.49
5000 40 384 344 384 48.6 326 384 72.4 0.41
150 EMS 134 384 267 384 345.2 233 384 474.5 0.44

Table 12. Cell and 96 -Well Plate Counts: Experiment 2 (+S9) 4 -Hour Exposure

Treatment Cell counts $  Viability § Resistant mutants §
(μg/ml)     after day 2 after day 2
        2 cells/well  2000 cells/well 
    0 h 24 h 48 h                
0 A 8.67 7.26 7.31 75 76 81 73 17 18 16 16
  B 8.77 6.69 7.26 74 74 70 77 16 14 19 17
39.06 A 8.54 7.46 6.80 NP NP   NP NP  
  B 8.35 7.19 7.27 NP NP   NP NP  
78.13 A 7.61 7.62

7.30

NP NP   NP NP  
  B 8.75 6.99 6.63 NP NP   NP NP  
156.25 A 8.10 7.56 7.33 77 80   16 21  
  B 8.01 8.11 6.98 79 73   18 20  
312.5 A 8.33 7.80 5.76 76 82   16 15  
  B 8.36 7.26 6.69 87 81   18 15  
625 A 6.10 7.60 7.15 77 75   18 15  
  B 5.50 6.35 6.25 85 80   17 19  
1250 A 5.95 5.85 6.70 87 87   21 22  
  B 5.90 6.75 7.30 85 87   17 18  
2500 A 7.10 5.10 6.60 92 88   17 22  
  B 6.20 4.95 7.65 89 86   24 16  
5000 A 4.50 6.60 7.20 87 79   21 20  
  B 4.55 5.30 6.75 89 87     24 23    
Positive control CP (μg/ml)
1.5 A 8.25 6.82 5.94 74 66     67 52    
  B 8.35 6.07 5.81 74 60     56 50    

Table 13. Statistical Analysis: Experiment 2 (+S9) 4-Hour Exposure

Treatment   SG %RSG %V RTG MF§
(μg/ml)            
0 12.7 100 75.99 1 125.12
39.06 Ø 12.88 98    
78.13 Ø 12.72 94    
156.25 14.01 102 81.66 1.09 133.06
312.5 11.72 88 94.51 1.09 96.46
625 11.68 61 87.3 0.71 113.45
1250 11.03 59 115.65 0.9 98.16
2500 8.95 54 129.17 0.91 89.16
5000 10.38 42 110.65 0.62 117.62
Positive control EMS
Treatment SG %RSG %V RTG MF§
(μg/ml)          
1.5   9.47 71 62.51 0.58 705.3

Test for linear trend

Slope -2.07E-09
Variance 8.32E-18
b²/Sb 0.513

Table 14. Large and Small Colonies Analysis: Experiment 2 (+S9) 4 -Hour Exposure

Treatment Viability # Small colonies # Large colonies #
(μg/ml) after day 2 after day 2 after day 2
0 A 75 76 81 73 8 7 8 6 9 11 8 10
  B 74 74 70 77 7 8 11 9 9 6 8 8
156.25 A 77 80   7 9   9 12  
  B 79 73   10 9   8 11  
312.5 A 76 82   7 7   9 8  
  B 87 81   8 9   10 6  
625 A 77 75   5 7   13 8  
  B 85 80   6 9   11 10  
1250 A 87 87   10 9   11 13  
  B 85 87   8 10   9 8  
2500 A 92 88   9 5   8 17  
  B 89 86   11 6   13 10  
5000 A 87 79   9 7   12 13  
  B 89 87   10 8   14 15  
1.5 CP A 74 66   47 38   20 14  
  B 74 60     40 37     16 13    

Mutation frequencies

Treatment  Viable Small colonies  Large colonies Proportion small colony mutants
(μg/ml)
  Mutants   Mutants  
  Yv Nv Ym Nm MF§ Ym Nm MF§
0 168 768 704 768 57.3 699 768 61.9 0.48
156.25 75 384 349 384 58.5 344 384 67.4 0.47
312.5 58 384 353 384 44.5 351 384 47.5 0.48
625 67 384 357 384 41.8 342 384 66.3 0.39
1250 38 384 347 384 43.8 343 384 48.8 0.47
2500 29 384 353 384 32.6 336 384 51.7 0.39
5000 42 384 350 384 41.9 330 384 68.5 0.39
1.5 CP 110 384 222 384 438.3 321 384 143.3 0.72

Table 15. Historical Vehicle and Positive Control Mutation Frequencies

Experiments -S9

Vehicle control Positive control
MF MF
145.91 950.8
120.76 1112.08
143.66 896.5
162.69 1229.56
158.66 1390.11
144.88 1458.54
105.22 1119.99
95.59 1090.89
114.37 1030.44
140.14 1014.32
99.14 1219.66
110.92 861.66
135.32 880.2
165.68 1305.45
125.21 905.45
118.81 1456.13
132.29 971.93
125.59 783.41
130.09 1021.61
160.24 674.85

Table 16. Historical Vehicle and Positive Control Mutation Frequencies

Experiments +S9

Vehicle control Positive control
MF MF
96.54 1073.42
120.03 1221.59
151.9 830.77
140.46 1320.32
126.59 742.1
175.99 1137.22
179.16 1474.77
110.11 931.18
107.82 892.85
133.99 1335.45
118.75 796.22
127.35 613.66
134.47 1089.84
131.07 905.61
118.37 1427.97
108.9 963.74
141.92 1000
109.28 724.93
127.28 1120.01
156.35 695.46
Conclusions:
Interpretation of results: negative. The test item did not induce any toxicologically significant increases in the mutant frequency at the TK +/- locus in L5178Y cells. The substance does not fulfill the classification criteria as mutagenic according to the CLP Regulation (EC No 1272/2008).
Executive summary:

The study was conducted according to a method that was designed to assess the potential mutagenicity of the test item on the thymidine kinase, TK +/-, locus of the L5178Y mouse lymphoma cell line. The method was designed to be compatible with the OECD Guidelines for Testing of Chemicals No.476 "In Vitro Mammalian Cell Gene Mutation Tests" adopted 21 July 1997, Method B17 of Commission Regulation (EC) No. 440/2008 of 30 May 2008, the US EPA OPPTS 870.5300 Guideline, and in alignment with the Japanese MITI/MHW guidelines for testing of new chemical substances.

Two independent experiments were performed. In Experiment 1, L5178Y TK +/- 3.7.2c mouse lymphoma cells (heterozygous at the thymidine kinase locus) were treated with the test item at eight dose levels in duplicate, together with vehicle (R0 medium), and positive controls using 4-hour exposure groups both in the absence and presence of metabolic activation (2% S9). In Experiment 2, the cells were treated with the test item at eight dose levels using a 4-hour exposure group in the presence of metabolic activation (1% S9) and a 24-hour exposure group in the absence of metabolic activation. The dose range of test item used in the main test was selected following the results of a preliminary toxicity test.

The maximum dose level used in the Mutagenicity Test was the maximum recommended dose of 5000 μg/mL. Precipitate of the test item was observed at and above 39.06 μg/mL in the Mutagenicity Test. The vehicle controls had mutant frequency values that were acceptable for the L5178Y cell line at the TK +/- locus. The positive control treatment induced marked increases in the mutant frequency indicating the satisfactory performance of the test and of the activity of the metabolizing system.

The test item did not induce any toxicologically significant increases in the mutant frequency at any of the dose levels, either with or without metabolic activation, in either the first or the second experiment.

As the test item did not induce any toxicologically significant increases in the mutant frequency at the TK +/- locus in L5178Y cells, the substance does not fulfill the classification criteria as mutagenic according to the CLP Regulation (EC No 1272/2008).

Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
experimental study
Adequacy of study:
key study
Study period:
09.4.2015 - 21.5.2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study was performed according to recommended Guidelines (OECD Guidelines for Testing of Chemicals No. 473 " In Vitro Mammalian Chromosome Aberration Test", adopted 26 September 2014) and GLP.
Qualifier:
according to guideline
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
Version / remarks:
Adopted 26 September 2014
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
Certificate is attached to the study report
Type of assay:
other: In vitro mammalian chromosome aberration test
Target gene:
Structural chromosomal aberrations
Species / strain / cell type:
lymphocytes: metaphase cells of normal human lymphocytes
Details on mammalian cell type (if applicable):
CELLS USED
- Source of cells: For each experiment, sufficient whole blood was drawn from the peripheral circulation of a non-smoking volunteer (aged 18-35) who had been previously screened for suitability.

- Suitability of cells: Human peripheral blood lymphocytes are recognized in the OECD 473 guidelines as being a suitable cell line for the Mammalian Chromosome Aberration Test. The volunteers of the cells had not knowingly been exposed to high levels of radiation or hazardous chemicals and had not knowingly recently suffered from a viral infection.

- Cell cycle length, doubling time or proliferation index: The cell-cycle time for the lymphocytes from the donors used in this study was determined using BrdU (bromodeoxyuridine) incorporation to assess the number of first, second and third division metaphase cells and so calculate the average generation time (AGT). The mean value of the AGT for the pool of regular donors used in this laboratory has been determined to be approximately 16 hours under typical experimental exposure conditions.

- Sex, age and number of blood donors if applicable: The details of the donors used are:
Preliminary Toxicity Test: male, aged 34 years
Main Experiment: male, aged 29 years

- Whether whole blood or separated lymphocytes were used if applicable: heparinized whole blood

MEDIA USED
- Type and identity of media including CO2 concentration if applicable: Cells (whole blood cultures) were grown in Eagle's minimal essential medium with HEPES buffer (MEM), supplemented “in-house” with L-glutamine, penicillin/streptomycin,
amphotericin B and 10% foetal bovine serum (FBS), at approximately 37 ºC with 5% CO2 in humidified air. The lymphocytes of fresh heparinized whole blood were stimulated to divide by the addition of phytohaemagglutinin (PHA).

- Properly maintained: yes


Metabolic activation:
with and without
Metabolic activation system:
S9
Test concentrations with justification for top dose:
0, 0.09, 0.188, 0.375, 0.75, 1.25, 2.5, 5 μg test item/mL

The molecular weight of the test item was supplied as 843; therefore, the maximum dose level was 2000 μg/mL, which was the maximum recommended dose level. The dose range for the Preliminary Toxicity Test was 0, 7.81, 15.63, 31.25, 62.5, 125, 250, 500, 1000 and 2000 μg/mL. The selection of the maximum dose level for the Main Experiment was based on the lowest precipitating dose level and was 5 μg/mL for both the 4(20)-hour exposure groups and for the continuous exposure group.
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: Minimal Essential Medium
- Justification for choice of solvent/vehicle: The test item was suspended in Minimal Essential Medium (MEM) at 20 mg/mL as it did form a suspension suitable for dosing at this concentration.
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Remarks:
Minimal Essential Medium
True negative controls:
no
Positive controls:
yes
Positive control substance:
cyclophosphamide
mitomycin C
Details on test system and experimental conditions:
METHOD OF APPLICATION: in medium

DURATION
- Preincubation period: 48 hours
- Exposure duration:
4-hour exposure to the test item without S9-mix, followed by 20-hour culture in treatment-free media prior to cell harvest.
4-hour exposure to the test item with S9-mix (2%), followed by 20-hour culture in treatment-free media prior to cell harvest.
24-hour continuous exposure to the test item without S9-mix prior to cell harvest.

- Expression time (cells in growth medium): 20 hours

STAIN (for cytogenetic assays): 5% Giemsa

NUMBER OF REPLICATIONS: 2

METHODS OF SLIDE PREPARATION AND STAINING TECHNIQUE USED:
Mitosis was arrested by addition of demecolcine (Colcemid 0.1 μg/mL) two hours before the required harvest time. After incubation with demecolcine, the cells were centrifuged, the culture medium was drawn off and discarded, and the cells re-suspended in 0.075M hypotonic KCl. After approximately fourteen minutes (including centrifugation), most of the hypotonic solution was drawn off and discarded. The cells were re-suspended and then fixed by dropping the KCl cell suspension into fresh methanol/glacial acetic acid (3:1 v/v). The fixative was changed at least three times and the cells stored at approximately 4 ºC to ensure complete fixation prior to
slide preparation.

The lymphocytes were re-suspended in several mL of fresh fixative before centrifugation and resuspension in a small amount of fixative. Several drops of this suspension were dropped onto clean, wet microscope slides and left to air dry. Each slide was permanently labeled with the appropriate identification data.

When the slides were dry they were stained in 5% Giemsa for 5 minutes, rinsed, dried and a cover slip applied using mounting medium.

NUMBER OF CELLS EVALUATED: A total of 2000 lymphocyte cell nuclei were counted and the number of cells in metaphase recorded and expressed as the mitotic index and as a percentage of the vehicle control value.

NUMBER OF METAPHASE SPREADS ANALYSED PER DOSE (if in vitro cytogenicity study in mammalian cells): Where possible the first 150 consecutive well-spread metaphases from each culture were counted, where there were at least 15 cells with aberrations (excluding gaps), slide evaluation was terminated.

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index

OTHER EXAMINATIONS:
- Determination of polyploidy: Cells with 69 chromosomes or more were scored as polyploid cells and the incidence of polyploid cells (%) (including endoreduplicated cells) is reported
- Other: Qualitative Slide Assessment
Rationale for test conditions:
Human peripheral blood lymphocytes are recognized in the OECD 473 guidelines as being a suitable cell line for the Mammalian Chromosome Aberration Test. The test methods of the study are designed to be compatible with the procedures indicated by the OECD Guidelines for Testing of Chemicals No. 473 " In Vitro Mammalian Chromosome Aberration Test".
Evaluation criteria:
The following criteria were used to determine a valid assay:
- The frequency of cells with chromosome aberrations (excluding gaps) in the vehicle control cultures was within the laboratory historical control data range.
- All the positive control chemicals induced a positive response (p≤0.01) and demonstrated the validity of the experiment and the integrity of the S9-mix.
- The study was performed using all three exposure conditions using a top concentration which meets the requirements of the current testing guideline.
- The required number of cells and concentrations were analyzed.
Statistics:
The frequency of cells with aberrations excluding gaps and the frequency of polyploid cells was compared, where necessary, with the concurrent vehicle control value using Fisher's Exact test. (Richardson et al. 1989).

A toxicologically significant response is recorded when the p value calculated from the statistical analysis of the frequency of cells with aberrations excluding gaps is less than 0.05 when compared to its concurrent control and there is a dose-related increase in the frequency of cells with aberrations which is reproducible. Incidences where marked statistically significant increases are observed only with gap-type aberrations will be assessed on a case by case basis.
Species / strain:
lymphocytes: metaphase cells of normal human lymphocytes
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not determined
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: No effect. There was no significant change in pH when the test item was dosed into media.
- Effects of osmolality: No effect. When the test item was dosed into media, the osmolality did not increase by more than 50 mOsm.
- Water solubility: The test item is not soluble in water

- Precipitation: Precipitate observations were made at the end of exposure in the parallel blood-free cultures and was noted at 5 μg/mL level in all three of the exposure groups in the parallel blood-free cultures.

RANGE-FINDING/SCREENING STUDIES:
The dose range for the Preliminary Toxicity Test was 0, 7.81, 15.63, 31.25, 62.5, 125, 250, 500, 1000 and 2000 μg/mL. The maximum dose was the maximum recommended dose level.

A precipitate of the test item was observed in the parallel blood-free cultures at the end of the exposure, at and above 31.25 μg/mL in the 4(20)-hour exposure groups and at all test item dose levels in the 24-hour exposure group. A precipitate in the pellet of the blood cultures of the4(20)-hour exposure groups at the end of exposure was noted when the cultures were centrifuged and washed at all test item dose levels. Precipitate of the test item was also observed on the slides of the 4(20)-hour exposure groups in the absence and presence of S9 mix at and above 15.63 μg/mL, and in the 24-hour exposure group at and above 7.81 μg/mL.

Microscopic assessment of the slides prepared from the exposed cultures showed that metaphase cells were present up to 500 μg/mL in all three of the exposure groups. The mitotic index data are presented in the study. The test item induced some modest evidence of toxicity but the dose selection for the main experiment was limited to include the lowest precipitating dose level as directed by the OECD 473 test guideline.

The selection of the maximum dose level for the Main Experiment was based on the lowest precipitating dose level and was 5 μg/mL for both the 4(20)-hour exposure groups and for the continuous exposure group.

COMPARISON WITH HISTORICAL CONTROL DATA:
The frequency of cells with chromosome aberrations (excluding gaps) in the vehicle control cultures were within the current historical control data range.
All the positive control chemicals induced a demonstrable positive response (p≤0.01) and confirmed the validity and sensitivity of the assay and the integrity of the S9-mix. For Historical Aberration Ranges, see Tables 8 and 9 in "Any other information on results incl. tables".

Preliminary Toxicity Test

Table 1. Mitotic Index - Preliminary Toxicity Test

Dose Level (μg/mL) 4(20)-Hour Without S9 4(20)-Hour With S9 24-Hour Without S9
Mitotic Index % of Control Mitotic Index % of Control Mitotic Index % of Control
0 6.3 100 6 100 4.05 100
7.81 3.65 58 3.7 62 3.45P‡ 85
15.63 3.8P‡ 60 5.15P‡ 86 3.45P‡ 85
31.25 -P‡ - -P‡ - -P‡ -
62.5 -P‡ - -P‡ - -P‡ -
125 -P‡ - -P‡ - -P‡ -
250 -P‡ - -P‡ - -P‡ -
500 -P‡ - -P‡ - -P‡ -
1000 -P‡ - -P‡ - NM P‡ NM
2000 -P‡ - -P‡ - NM P‡ NM

- = Not assessed for mitotic index

NM = No metaphases or insufficient metaphases suitable for scoring

P = Precipitate observed at end of exposure period in blood-free cultures

‡ = Precipitate observed on the slides

Chromosome Aberration Test – Main Experiment

Table 2. Mitotic Index – Main Experiment (4(20)-hour Exposure Groups)

Dose Level (μg/mL) 4(20)-Hour Without S9 4(20)-Hour With S9
A B Mean % of Control A B Mean % of Control
0 3.5 6.55 5.03 100 5.5 4.8 5.15 100
0.09 - - - - - - - -
0.188 - - - - - - - -
0.375 - - - - - - - -
0.75 - - - - - - - -
1.25 7.05 5.1 6.08 121 4.6 4.2 4.4 85
2.5 4.7 4 4.35 87 7.95 4 5.98 116
5 6.45P 3.6P 5.03 100 6.55P 7.4P 6.98 135
MMC 0.3 2.8 2.25 2.53 50 NA NA NA NA
CP 3 NA NA NA NA 1.55 1.4 1.48 29

MMC = Mitomycin C

CP = Cyclophosphamide

NA = Not applicable

- = Not assessed for mitotic index

P = Precipitate observed at end of exposure period in blood-free cultures

Table 3. Mitotic Index – Main Experiment (24-hour Exposure Group)

Dose Level (μg/mL) 4(20)-Hour Without S9
A B Mean % of Control
0 6.75 5.5 6.13 100
0.09 - - - -
0.188 - - - -
0.375 - - - -
0.75 - - - -
1.25 3.8 3.65 3.73 61
2.5 5.1 5.2 5.15 84
5 5.05P 4.6P 4.83 79
MMC 0.1 1.65 2.05 1.85 30

MMC = Mitomycin C

- = Not assessed for mitotic index

P = Precipitate observed at end of exposure period in blood-free cultures

Table 4. Results of Chromosome Aberration Test – Main Experiment 4(20)-hour Exposure Without Metabolic Activation (S9)

Treatment Group Replicate Mitotic
Index (%)
Number of
Cells Scored
Number of Aberrations Total Number of Aberrations Frequency of Aberrant Cells
Gaps Chromatid Chromosome Others
Breaks Exchanges Breaks Exchanges X (+ Gaps) (-Gaps) (+ Gaps) (-Gaps)
Vehicle Control
(MEM)
A 3.5 150 1 0 0 0 0 0 1 0 1 0
B 6.55 150 0 1 0 0 0 0 1 1 1 1
Total (100) 300 1 1 0 0 0 0 2 1 2 (0.7) 1 (0.3)
1.25 ug/mL A 7.05 150 0 0 0 0 0 0 0 0 0 0
B 5.1 150 0 0 0 0 0 0 0 0 0 0
Total (121) 300 0 0 0 0 0 0 0 0 0 (0.0) 0 (0.0)
2.5 ug/mL A 4.7 150 0 2 0 1 1 0 4 4 4 4
B 4 150 0 0 0 0 1 0 1 1 1 1
Total (87) 300 0 2 0 1 2 0 5 5 5 (1.7) 5 (1.7)
5 ug/mL A 6.45 150 1 0 0 0 0 0 1 0 1 0
B 3.6 150 2 0 0 1 0 0 3 1 3 1
Total (100) 300 3 0 0 1 0 0 4 1 4 (1.3) 1 (0.3)
Positive Control MMC 0.3 ug/mL A 2.8 44a 3 11 5 1 0 0 20 17 16 15
B 2.25 44a 3 10 14 5 1 0 33 30 17 15
Total (50) 88 6 21 19 6 1 0 53 47 33 (37.5) 30*** (34.1)

MMC = Mitomycin C

a Slide evaluation terminated when 15 metaphases with aberrations (excluding gaps) had been observed

*** P < 0.001

MEM Minimal Essential Medium

Table 5. Results of Chromosome Aberration Test – Main Experiment 4(20)-hour Exposure With Metabolic Activation (2% S9)

Treatment Group Replicate Mitotic
Index (%)
Number of
Cells Scored
Number of Aberrations Total Number of Aberrations Frequency of Aberrant Cells
Gaps Chromatid Chromosome Others
Breaks Exchanges Breaks Exchanges X (+ Gaps) (-Gaps) (+ Gaps) (-Gaps)
Vehicle Control
(MEM)
A 5.5 150 2 0 0 0 0 0 2 0 2 0
B 4.8 150 0 0 0 0 0 0 0 0 0 0
Total (100) 300 2 0 0 0 0 0 2 0 2 (0.7) 0 (0.0)
1.25 ug/mL A 4.6 150 1 0 0 0 0 0 1 0 1 0
B 4.2 150 0 0 0 0 0 0 0 0 0 0
Total (85) 300 1 0 0 0 0 0 1 0 1 (0.3) 0 (0.0)
2.5 ug/mL A 7.95 150 0 0 0 0 0 0 0 0 0 0
B 4 150 0 0 0 0 0 0 0 0 0 0
Total (116) 300 0 0 0 0 0 0 0 0 0 (0.0) 0 (0.0)
5 ug/mL A 6.55 150 0 0 0 0 0 0 0 0 0 0
B 7.4 150 1 0 0 0 0 0 1 0 1 0
Total (135) 300 1 0 0 0 0 0 1 0 1 (0.3) 0 (0.0)
Positive Control CP 3 ug/mL A 1.55 70a 1 14 1 0 0 0 16 15 15 15
B 1.4 73a 2 13 2 2 0 0 19 17 16 15
Total (29) 143 3 27 3 2 0 0 35 32 31 (21.7) 30*** (21.0)

CP = Cyclophosphamide

a Slide evaluation terminated when 15 metaphases with aberrations (excluding gaps) had been observed

*** P < 0.001

MEM Minimal Essential Medium

Table 6. Results of Chromosome Aberration Test – Main Experiment 24-hour Continuous Exposure

Without Metabolic Activation (S9)

Treatment Group Replicate Mitotic
Index (%)
Number of
Cells Scored
Number of Aberrations Total Number of Aberrations Frequency of Aberrant Cells
Gaps Chromatid Chromosome Others
Breaks Exchanges Breaks Exchanges X (+ Gaps) (-Gaps) (+ Gaps) (-Gaps)
Vehicle Control
(MEM)
A 6.75 150 1 0 0 0 0 0 1 0 1 0
B 5.5 150 0 0 0 0 0 0 0 0 0 0
Total (100) 300 1 0 0 0 0 0 1 0 1 (0.3) 0 (0.0)
1.25 ug/mL A 3.8 150 0 0 0 0 0 0 0 0 0 0
B 3.65 150 1 0 0 0 0 0 1 0 1 0
Total (61) 300 1 0 0 0 0 0 1 0 1 (0.3) 0 (0.0)
2.5 ug/mL A 5.1 150 0 0 0 0 0 0 0 0 0 0
B 5.2 150 2 1 0 0 0 0 3 1 3 1
Total (84) 300 2 1 0 0 0 0 3 1 3 (1.0) 1 (0.3)
5 ug/mL A 5.05 150 0 0 0 0 0 0 0 0 0 0
B 4.6 150 0 0 0 0 0 0 0 0 0 0
Total (79) 300 0 0 0 0 0 0 0 0 0 (0.0) 0 (0.0)
Positive Control CP 3 ug/mL A 1.65 29a 0 11 4 4 0 0 19 19 15 15
B 2.05 125a 0 13 5 0 0 0 18 18 15 15
Total (30) 154 0 24 9 4 0 0 37 37 30 (19.5) 30*** (19.5)

MMC = Mitomycin C

a Slide evaluation terminated when 15 metaphases with aberrations (excluding gaps) had been observed

*** P < 0.001

MEM Minimal Essential Medium

Table 7. Mean Frequency of Polyploid Cells (%),Main Experiment

Dose Level
(μg/mL)
Exposure Group
4(20)-Hour Without S9 4(20)-Hour With S9 24-Hour Without S9
0 0 0 0
1.25 0 0 0
2.5 0 0.3 0
5 0 0 0
MMC 0.4 0 NA NA
MMC 0.1 NA NA 0
CP 3 NA 0 NA

MMC = Mitomycin C

CP = Cyclophosphamide

NA = Not applicable

Table 8. Historical Aberration Ranges for Vehicle Control Cultures

4(20)-hour exposure
without S9
4(20)-hour exposure with
S9 (1%)
24-hour exposure without
S9
4(20)-hour exposure with
S9 (2%)
% cells
with
aberrations
(-gaps)
% cells
with
polyploids
% cells
with
aberrations
(-gaps)
% cells
with
polyploids
% cells
with
aberrations
(-gaps)
% cells
with
polyploids
% cells
with
aberrations
(-gaps)
% cells
with
polyploids
Minimum 0 0 0 0 0 0 0 0
Maximum 3 1 2 0.5 2.5 1 2 1
Mean 0.48 0.05 0.4 0.02 0.44 0.07 0.53 0.09
Standard Deviation 0.56 0.17 0.48 0.11 0.52 0.22 0.56 0.24
Number 88 88 87 87 86 86 87 87

Table 9. Historical Aberration Range for Positive Control Cultures

4(20)-hour exposure
without S9
4(20)-hour exposure with
S9 (1%)
24-hour exposure without
S9
4(20)-hour exposure with
S9 (2%)
% cells
with
aberrations
(-gaps)
% cells
with
polyploids
% cells
with
aberrations
(-gaps)
% cells
with
polyploids
% cells
with
aberrations
(-gaps)
% cells
with
polyploids
% cells
with
aberrations
(-gaps)
% cells
with
polyploids
Minimum 14 0 10 0 8.7 0 7.3 0
Maximum 72 1 53 1 68 1 54 1
Mean 39.86 0.02 30.66 0.02 39.09 0.02 25.32 0.06
Standard Deviation 14.04 0.13 9.65 0.12 14.57 0.013 10.09 0.21
Number 88 88 87 87 87 87 88 88
Conclusions:
The test item did not induce any statistically significant increases in the frequency of cells with chromosome aberrations, in either the absence or presence of a liver enzyme metabolizing system. The test item was therefore considered to be non-clastogenic to human lymphocytes in vitro.

The substance does not fulfill the classification criteria as mutagenic according to the CLP Regulation (EC No 1272/2008).
Executive summary:

Duplicate cultures of human lymphocytes, treated with the test item, were evaluated for chromosome aberrations at three dose levels, together with vehicle and positive controls. In this study, the main experiment was performed using three exposure conditions; 4 hours in the presence of an induced rat liver homogenate metabolizing system (S9), at a 2% final concentration with cell harvest after a 20-hour expression period, a 4 hours exposure in the absence of metabolic activation (S9) with a 20-hour expression period and a 24-hour exposure in the absence of metabolic activation.

The dose levels selected for the main experiment were based on the results of the preliminary toxicity test and were limited to include the lowest precipitating dose level.

All vehicle (Minimal Essential Medium) controls had frequencies of cells with aberrations within the range expected for normal human lymphocytes.

All the positive control items induced statistically significant increases in the frequency of cells with aberrations. The metabolic activation system was therefore shown to be functional and the test method itself was operating as expected.

The test item did not induce any statistically significant increases in the frequency of cells with aberrations, using a dose range that included a dose level that was the lowest precipitating dose level.

The test item was considered to be non-clastogenic to human lymphocytes in vitro. The substance does not fulfil the criteria as mutagenic according to the CLP Regulation (EC No 1272/2008).

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

Genetic toxicity in vivo

Description of key information

Justification for selection of genetic toxicity endpoint
No study was selected, since all three in vitro studies were negative.

Endpoint conclusion
Endpoint conclusion:
no study available

Mode of Action Analysis / Human Relevance Framework

There is no reason to believe that the negative results of all the three in vitro tests in genetic toxicity would not be relevant to humans. The substance is not classified as mutagenic.

Additional information

All the in vitro studies were GLP compliant guideline studies and negative in terms of adverse effects observed. There are no data gaps in genetic toxicity. Since all three in vitro studies were negative, there is no need to perform in vivo studies on genetic toxicity. Therefore, there is no reason to believe that these results would not be relevant to humans.

Short description of key information:
Clearly negative in vitro studies - both with and without metabolic activation.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

The substance does not fulfill the classification criteria as mutagenic according to the CLP Regulation (EC No 1272/2008). All three in vitro studies were negative.

Reverse Mutation Assay 'Ames Test' using Salmonella typhimurium and Escherichia coli: the test item was considered to be non-mutagenic under the conditions of the test.

L5178Y TK +/- Mouse Lymphoma Assay: the test item did not induce any toxicologically significant increases in the mutant frequency at the TK +/- locus in L5178Y cells.

Chromosome Aberration Test in Human Lymphocytes in vitro: the test item was considered to be non-clastogenic to human lymphocytes in vitro.