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Study Information
Study Attribute Value
CEBS Accession Number: 002-01694-0013-0000-6
Chemical Name: Benzidine dihydrochloride
CASRN: 531-85-1
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 011624
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: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Water 
 0         
 59 96 100 56 59
    61 95 105 57
    64 114 139 73
    61 95 89 49
Test Chemical Benzidine dihydrochloride 
13         
 49 80 128 87 68
    61 100 91 49
  
26         
 42 59 83 67 80
    49 66 135 92
  
51         
 46 32 158 114 121*
    51 31 195 128
  
64         
 28 6 156 186 175*
    38 16 186 165
  
80         
 26 5 140 176 192*
    23 5 145 209
Positive Control Ethyl Methane Sulfonate 
500         
 36 36 534 499 442*
    39 45 499 423
    37 41 446 405

Nonactivation Trial: 2 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Water 
 0         
 61 100 134 73 62
    64 100 114 60
    59 100 98 56
    65 99 121 62
Test Chemical Benzidine dihydrochloride 
26         
 49 66 109 75 68
    65 82 120 61
  
33         
 67 69 135 68 62
    70 73 119 57
  
41         
 57 40 131 77 93
    59 44 191 108
  
51         
 41 15 171 138 148*
    36 13 171 158
  
64         
 19 3 131 232
  
80         
   
Positive Control Ethyl Methane Sulfonate 
500         
 39 37 663 564 619*
    40 41 716 602
    34 36 697 690

Induced S9 Trial: 1 Experiment Call: Rejected
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Water 
 0         
 60 108 156 87 71
    61 97 119 65
    56 93 115 69
    58 102 110 63
Test Chemical Benzidine dihydrochloride 
13         
 57 90 122 72 66
    53 85 97 61
  
26         
 50 60 52 35 60
    71 74 183 86
  
51         
 50 13 175 117 148*
    33 10 174 178
  
64         
 16 3 53 108 169*
    25 4 174 229
  
80         
 9r 1 146 551
  
100         
 9r 1 100 364
    7r 1 85 386
Positive Control 3-Methylcholanthrene 
6         
 21 8 313 505 488*
    17 5 221 438
    17 6 266 522

Induced S9 Trial: 2 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Water 
 0         
 107 97 315 99 97
    102 89 322 105
    106 106 256 80
    117 107 364 104
Test Chemical Benzidine dihydrochloride 
11.37      
 84# 77 373 148 135
    110 93 403 122
  
22.73      
 87 73 394 151 130
    99 83 322 109
  
45.47      
 70 30 1088 521 510*
    67 29 1008 500
  
56.83      
 26 4 903 1180 1041*
    33 6 901 901
  
71.04      
   
Positive Control 3-Methylcholanthrene 
5         
 55 26 827 498 526*
    49# 21 838.5 576
    65 28 979 503

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