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Study Information
Study Attribute Value
CEBS Accession Number: 002-01385-0002-0000-1
Chemical Name: 3,3',5,5'-Tetramethylbenzidine
CASRN: 54827-17-7
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 509405
Study Result: Negative


Table Instructions and Notes:
Studies are indicated to be "Nontoxic" when the observed reductions in relative total growth did not indicate that the maximum tolerated dose was achieved.

Nonactivation Trial: 1 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 81 96 41 17 22
    77 96 67 29
    82# 106 53 22
    71 102 43 20
Test Chemical 3,3',5,5'-Tetramethylbenzidine 
12.5       
 68# 115 28.5 14 14
    88# 146 34.5 13
  
25         
 75 126 40 18 12
    85# 144 16.5 6
  
50         
 84 68 39 16 19
    79 80 51 22
  
75         
 82 81 78 32 24
    92 86 44 16
  
100         
 44 9 91 69 63*
    52 15 91 58
  
125         
 49 31 78 53 42*
    70 55 64 31
  
150         
 39 2 132 113 83*
    61 12 99 54
  
200         
   
Positive Control Ethyl Methane Sulfonate 
500         
 20 12 607 1012 1000*
    17 8 514 988

Nonactivation Trial: 2 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 105 105 41 13 21
    76 99 49 22
    96 105 69 24
    93 91 68 24
Test Chemical 3,3',5,5'-Tetramethylbenzidine 
50         
 97 68 61 21 20
    90 82 39 14
    62 54 47 25
  
75         
 89# 46 42 16 25
    86 32 83 32
    69 28 54 26
  
100         
 56 6 110 65 52*
    45 3 86 63
    89 30 71 27
  
125         
 94 15 85 30 25
    67 15 47 23
    50 4 34 23
  
150         
 72 16 58 27 23
    108 17 60 19
    42 4 29 23
  
200         
 83 12 73 29 25
    72 12 64 30
    102 25 45 15
Positive Control Ethyl Methane Sulfonate 
500         
 11 4 474 1394 1126*
    16 7 438 942
    11 4 344 1042

Nonactivation Trial: 3 Experiment Call: Equivocal
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 94 92 128 45 35
    107 100 117 37
    119 99 103 29
    105 109 88 28
Test Chemical 3,3',5,5'-Tetramethylbenzidine 
50         
 101 82 103 34 33
    101 78 83 27
    94 84 107 38
  
75         
 87 46 155 60 62*
    91 54 121 44
    95 32 234 83
  
100         
 67 15 166 83 60*
    101 33 161 53
    101 37 130 43
  
125         
 101 22 171 56 51*
    98 20 121 41
    86 11 145 56
  
150         
 52 9 106 68 56*
    79 18 97 41
    82 17 144 58
  
200         
 75# 9 104 46 39
    87# 12 85 33
Positive Control Ethyl Methane Sulfonate 
500         
 7r 1 333 1514 966*
    35 8 530 510
    11 2 462 1422

Nonactivation Trial: 4 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 63# 95 156 83 76
    71# 102 154 73
    66# 102 143 73
Test Chemical 3,3',5,5'-Tetramethylbenzidine 
40         
 90 86 187 69 61
    70 105 131 62
    91 133 139 51
  
60         
 71 74 149 70 72
    70 76 169 80
    96 99 191 67
  
80         
 81 48 143 59 60
    74 42 154 69
    98 59 154 53
  
100         
 73 27 189 86 78
    94# 26 226 80
    75 36 155 69
  
120         
 78# 12 134 57 67
    86 27 187 72
    77 14 168 73
  
150         
 86 13 180 70 84
    65# 9 181 93
    67# 8 179 89
Positive Control Ethyl Methane Sulfonate 
250         
 33 33 844 853 684*
    42# 43 794 630
    48# 44 820 569

Non-Induced S9 Trial: 1 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 97 98 265 91 80
    113 101 269 79
    109# 89 249 76
    115 112 256 74
Test Chemical 3,3',5,5'-Tetramethylbenzidine 
50         
 84 84 223 89 89
    81 60 217 89
  
100         
 74# 34 210 95 101
    77# 34 166 72
    55 17 225 136
  
200         
 84 39 234 93 83
    72 31 179 83
    80 23 174 72
  
300         
 39 6 141 122 119*
    61 12 222 122
    82 19 276 113
Positive Control 3-Methylcholanthrene 
7         
 31# 7 363 390 393*
    36# 12 382.5 359
    33 20 422 428

Non-Induced S9 Trial: 2 Experiment Call:
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 82# 89 105 43 32
    93 106 101 36
    89 88 60 22
    94 117 80 28
Test Chemical 3,3',5,5'-Tetramethylbenzidine 
100         
 88 73 99 37 36
    82 53 99 40
    97 81 91 31
  
150         
 92 65 82 30 33
    97 48 105 36
    89 54 93 35
  
200         
 96 55 92 32 35
    107 45 118 37
    77 14 82 35
  
300         
 83 53 66 26 39
    88 48 97 37
    73 4 118 54
  
400         
 78 32 91 39 37
    104 28 129 41
    113 27 102 30
Positive Control 3-Methylcholanthrene 
3.5       
 94 61 423 151 145*
    91 52 447 163
    80 53 292 121

Induced S9 Trial: 1 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 84 113 106 42 47
    97 110 104 36
    72 92 117 54
    76 85 127 56
Test Chemical 3,3',5,5'-Tetramethylbenzidine 
12.5       
 77# 86 132 57 48
    102 100 125 41
    95 118 134 47
  
25         
 86 103 123 48 44
    101 99 125 41
  
50         
 101 153 122 40 52
    69 77 103 50
    83# 73 160.5 65
  
100         
 96 86 100 35 33
    87 45 93 36
    90 57 76 28
  
200         
 65 7 140 72 47
    61 36 52 28
    52 31 63 40
  
400         
 31r 4 59 64
Positive Control 3-Methylcholanthrene 
5         
 330*
    7r 1 78 355
    15 2 145 330

Induced S9 Trial: 2 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 107 111 97 30 37
    93 85 90 32
    97 99 112 38
    103 105 140 45
Test Chemical 3,3',5,5'-Tetramethylbenzidine 
12.5       
 115 71 133 39 34
    101# 92 90 30
    79 56 82 35
  
25         
 62 64 133 71 58*
    86 56 150 58
    77 59 99 43
  
50         
 95 52 113 40 38
    106 43 128 40
    110 68 114 35
  
100         
 79 40 57 24 24
    125r 39 69 18
    86 31 62 24
  
200         
 56 14 115 69 44
    40 5 24 20
    78 17 104 45
  
400         
 21# 1 20 32 55*
    64 8 142 74
    80 13 142 59
Positive Control 3-Methylcholanthrene 
5         
 22 4 245 374 314*
    19 3 169 305
    33# 5 260 263

Footnotes:
Asterisks(*) indicate significant responses.
r = rejected value due to quality control criteria
# = reduced sample size because of the loss of one culture dish due to contamination