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Study Information
Study Attribute Value
CEBS Accession Number: 002-01385-0003-0000-2
Chemical Name: 3,3',5,5'-Tetramethylbenzidine
CASRN: 54827-17-7
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 831590
Study Result: Positive


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: Inconclusive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Solvent 
 0         
 99 110 139 47 51
    86 97 121 47
    95 102 122 43
    84 91 164 65
Test Chemical 3,3',5,5'-Tetramethylbenzidine 
15.4       
 91 82 242 89 79
    78# 62 160 69
  
30.7       
 99 98 250 84 79*
    73 74 163 74
  
51.2       
 70 30 278 133 133*
    61 14 243 133
  
100         
 58 18 504 289 208*
    72 33 275 128
  
125         
 67 19 438 217 181*
    74 27 320 144
Positive Control Ethyl Methane Sulfonate 
500         
 42 36 990 783 617*
    46 39 1125 821
    98 120 726 248

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         
 58 89 75 43 49
    55 74 111 68
    72# 137 93 43
    58 101 73 42
Test Chemical 3,3',5,5'-Tetramethylbenzidine 
42         
 45 12 96 72 62
    34 10 52 51
  
53         
 15 5 40 88 79
    30 6 63 69
  
66         
    25 3 69 91
  
82         
   
Positive Control Ethyl Methane Sulfonate 
500         
 40 50 955 803 843*
    30 29 813 908
    37 41 903 817

Nonactivation Trial: 3 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 85 106 54 21 24
    86 81 74 29
    83 116 41 17
    84 97 75 30
Test Chemical 3,3',5,5'-Tetramethylbenzidine 
26         
 64 93 82 43 37*
    89 111 73 27
    74 100 91 41
  
33         
 71 92 68 32 23
    120 163 53 15
    124r 161 116 31
  
41         
 81 98 74 30 32
    76 89 102 45
    85 94 54 21
  
51         
 73 53 101 46 59*
    66 28 151 76
    73 60 118 54
  
64         
   
   
Positive Control Ethyl Methane Sulfonate 
500         
 59 50 1163 655 702*
    49 45 1110 750
    64 59 1354 702

Induced S9 Trial: 1 Experiment Call: Rejected
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 75 111 47 21 26
    53 77 46 29
    73 112 61 28
Test Chemical 3,3',5,5'-Tetramethylbenzidine 
41         
 78 138 55 24 21
    83 146 48 19
  
51         
 89 142 69 26 27
    60 103 52 29
  
64         
 72 118 22 10 17
    68 116 47 23
  
80         
 68 114 47 23 25
    69 117 56 27
  
100         
 72 118 51 24 24
    70 106 53 25
  
125         
 60 84 46 26 30
    61 83 64 35
Positive Control 3-Methylcholanthrene 
5         
 43 54 217 168 162*
    47 56 247 176
    54 60 230 143

Induced S9 Trial: 2 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 100 116 331 110 102
    112 99 399 119
    104 85 236 76
Test Chemical 3,3',5,5'-Tetramethylbenzidine 
52         
 85# 100 225 88 83
    81# 135 163 67
    55 74 155 94
  
66         
 80 79 276 116 85
    80 127 150 62
    78 105 179 76
  
82         
 82 78 212 86 85
    93 99 213 77
    88 81 240 91
  
102         
 86 81 204 79 74
    82 74 172 70
    91 95 199 73
  
128         
 105 90 154 49 54
    118 106 209 59
    97 87 161 55
Positive Control 3-Methylcholanthrene 
5         
 61 33 814 445 460*
    77 38 1002 437
    60 32 900 497

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