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Study Information
Study Attribute Value
CEBS Accession Number: 002-01391-0012-0000-9
Chemical Name: 3,3'-Dimethylbenzidine
CASRN: 119-93-7
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 570901
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: No Call
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 85 118 58 23 37
    77 102 67 29
    64 96 88 46
    56# 84 87 52
Test Chemical 3,3'-Dimethylbenzidine 
3.9       
 69 95 75 36 44
    61 90 94 51
  
7.8       
 68 91 68 33
  
15.6       
 56# 74 65 39 44
    66 87 100 50
  
31.3       
 65 87 114 58 55
    67 92 104 52
  
62.5       
 62 78 127 69 77*
    73 95 185 85
  
125         
 46 13 110 80 70*
    45# 25 82.5 61
  
250         
   
Positive Control Ethyl Methane Sulfonate 
500         
 3r 1 60 600
    1r 0 28.5 950

Nonactivation 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         
 75 107 40 18 19
    78 98 32 14
    77 111 49 21
    71 85 50 24
Test Chemical 3,3'-Dimethylbenzidine 
12.5       
 83 94 34 14 16
    84 101 52 21
    76 111 33 14
  
25         
 76 98 58 25 28
    61 70 56 31
    70 79 59 28
  
50         
 63 65 39 21 25
    69 73 50 24
    71# 65 61.5 29
  
100         
 38 14 78 68 57*
    48 24 81 56
    66 37 90 46
  
150         
 137*
    39# 2 132 113
    38 2 183 160
  
175         
   
   
Positive Control Ethyl Methane Sulfonate 
250         
 55 57 672 410 346*
    65 62 584 299
    72 72 704 328

Nonactivation Trial: 4 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 74 85 34 15 19
    100 100 52 17
    112 101 61 18
    89 114 65 24
Test Chemical 3,3'-Dimethylbenzidine 
50         
 113 82 41 12 17
    99 94 67 23
    101 96 48 16
  
75         
 71 47 75 35 28
    104 72 69 22
    85# 70 69 27
  
100         
 96 35 118 41 40*
    104 40 128 41
    85 38 127 50
    106 49 96 30
  
125         
 79 18 224 94 91*
    66 5 247 125
    67 12 178 89
    87 20 146 56
  
150         
 73 4 345 157 128*
    59# 3 285 161
    49 3 226 155
    79 58 94 39
Positive Control Ethyl Methane Sulfonate 
250         
 71 53 901 423 374*
    75 58 779 345
    66 53 702 355

Induced S9 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 94 52 21 28
    92 117 97 35
    92 90 80 29
Test Chemical 3,3'-Dimethylbenzidine 
15.6       
 77 92 82 36 38
    109 73 140 43
    117 91 122 35
  
31.3       
 101 99 142 47 42
    80# 88 111 46
    116# 112 109.5 31
  
62.5       
 87 91 134 51 44
    96 99 103 36
  
125         
 87# 61 165 63 52*
    77 66 105 45
    76 66 107 47
  
150         
 78 36 144 61 54*
    92 59 129 47
  
175         
 73 5 272 124 88*
    88 31 138 52
Positive Control 3-Methylcholanthrene 
2.5       
 61 31 481 262 252*
    57 22 416 242

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         
 89 131 59 22 31
    91 96 74 27
    83 88 81 33
    83 85 104 42
Test Chemical 3,3'-Dimethylbenzidine 
31.3       
 81 82 93 38 38
    75# 89 85 38
  
62.5       
 84 87 72 29 33
    94# 81 111 39
    92 68 82 30
  
125         
 79 56 118 50 37
    74 33 68 31
    93# 32 81 29
  
150         
 59 50 88 50 62*
    75 34 147 65
    53 41 114 71
  
175         
 81 22 191 78 75*
    76 18 188 82
    84 30 165 66
Positive Control 3-Methylcholanthrene 
2.5       
 51 26 504 332 278*
    69 46 462 225

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