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Study Information
Study Attribute Value
CEBS Accession Number: 002-01694-0014-0000-7
Chemical Name: Benzidine dihydrochloride
CASRN: 531-85-1
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 018793
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         
 104 87 53 17 19
    106 115 65 20
    105 99 64 20
    124r 107 79 21
Test Chemical Benzidine dihydrochloride 
6.25      
 101 92 76 25 23
    99 101 61 21
  
12.5       
 103 105 57 18 17
    96 107 43 15
  
25         
 96 91 84 29 32*
    95 86 101 35
  
50         
 182r 119 186 34
    105# 90 147 47
  
100         
 96 20 351 122 124*
    89 19 338 127
  
150         
   
Positive Control Ethyl Methane Sulfonate 
500         
 92# 38 1286 468 622*
    73 27 1338 611
    50 22 1170 788

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         
 99# 90 57 19 15
    102 116 45 15
    99 100 35 12
    101 94 39 13
Test Chemical Benzidine dihydrochloride 
12.5       
 103 115 41 13 16
    103 106 59 19
  
25         
 100 102 54 18 17
    101 107 47 16
  
50         
 87 72 75 29 30*
    102 92 96 31
  
75         
 88 46 141 53 60*
    79 38 121 51
    71 38 158 75
  
100         
 64 4 170 89 83*
    53 4 116 73
    89 17 233 88
  
125         
   
   
Positive Control Ethyl Methane Sulfonate 
500         
 26 13 585 736 651*
    35 14 773 729
    51 30 740 488

Induced S9 Trial: 1 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Water 
 0         
 101 94 95 31 27
    93 94 73 26
    102 115 85 28
    99 97 73 24
Test Chemical Benzidine dihydrochloride 
6.25      
 102 92 80 26 30
    97# 92 96 33
  
12.5       
 72 72 70 33 35
    63 71 69 37
  
25         
 99# 79 120 40 37
    82 61 83 34
  
50         
 79 46 185 79 75*
    62 46 134 72
  
100         
 68 29 285 139 152*
    75 29 367 164
  
150         
 69 14 579 278 261*
    72 18 526 244
  
200         
 48 5 620 429
Positive Control 3-Methylcholanthrene 
5         
 50 16 495 333 355*
    54 22 500 309
    45# 11 565.5 424

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         
 120r 149 265 74 75
    105 121 227 72
    86 69 218 85
    102 110 204 66
Test Chemical Benzidine dihydrochloride 
6.25      
 83 107 228 92
    137r 200 192 47
  
12.5       
 111 120 246 74
    133r 175 157 39
  
25         
 104 113 290 93 95
    107 77 316 98
  
50         
 97 72 494 170 232*
    55 35 490 295
  
75         
 41 13 517 417 492*
    26 4 362 467
    26 3 470 591
Positive Control 3-Methylcholanthrene 
5         
 250*
    16 2 104 212
    20 2 176 289

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