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Study Information
Study Attribute Value
CEBS Accession Number: 002-01391-0013-0000-0
Chemical Name: 3,3'-Dimethylbenzidine
CASRN: 119-93-7
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 576643
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         
93 104 103 37 37
    85 105 94 37
    82 112 97 39
    69 78 74 36
Test Chemical 3,3'-Dimethylbenzidine
13         
63 90 113 60 47
    95 123 97 34
 
26         
77 105 113 49
 
51         
79 43 152 64 81*
    80 61 236 98
 
64         
47 8 286 201
 
80         
 
100         
   
Positive Control Ethyl Methane Sulfonate
500         
32 23 957 992 1086*
    32 24 1088 1133
    30 25 1026 1134

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         
63 104 56 29 25
    58 106 48 27
    57 94 31 18
    58 97 41 24
Test Chemical 3,3'-Dimethylbenzidine
26         
53 84 81 51 44*
    58 78 63 36
 
33         
59 95 79 44 44*
    66 102 86 43
 
41         
36 27 107 100 75*
    39 54 58 50
 
51         
40 17 108 91 95*
    31 18 91 99
 
64         
18 3 60 112 94*
    27 6 61 75
 
80         
 
100         
   
Positive Control Ethyl Methane Sulfonate
500         
45 57 915 673 687*
    40 48 772 643
    38 41 838 745

Nonactivation Trial: 3 Experiment Call: Positive
  Conc.
ug/mL
Cloning
Efficiency
Relative Total
Growth
Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide
 0         
72 103 64 30 29
    75 92 80 36
    79 105 50 21
Test Chemical 3,3'-Dimethylbenzidine
26         
73 94 64 29 37
    80# 104 105 44
 
33         
82 100 83 34 41
    73 100 105 48
 
41         
72 79 126 58 54*
    73 78 109 50
 
51         
62 40 231 124 104*
    74 65 188 84
 
64         
58 34 186 108 140*
    48 18 245 172
 
80         
28 4 162 195 228*
    25 3 195 262
 
100         
   
Positive Control Ethyl Methane Sulfonate
500         
50 44 821 544 537*
    44 48 736 564
    49 54 742 503

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         
94 104 138 49 44
    82 89 140 57
    104 112 114 37
    87 95 89 34
Test Chemical 3,3'-Dimethylbenzidine
13         
66 77 92 47 47
    72 90 80 37
    67 81 112 56
 
26         
89 84 141 53 50
    90 79 118 44
    91 96 148 54
 
51         
88 68 147 56 62
    106 89 237 74
    80 72 134 56
 
102         
88 90 93 35 49
    85 79 131 52
    81 69 145 60
 
205         
63 32 203 108 106*
    66 33 173 87
    66 35 240 122
 
256         
49 16 319 218 171*
    48 14 203 142
    45 13 206 152
 
320         
331*
    15 1 160 348
    15 1 143 314
 
400         
   
   
Positive Control 3-Methylcholanthrene
5         
77 80 281 122 140*
    79 89 413 175
    81 87 297 122

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         
65 127 85 44 41
    55 101 76 46
    61 72 61 34
Test Chemical 3,3'-Dimethylbenzidine
105         
61 51 122 67 71*
    59 98 135 76
 
131         
62# 47 179 97 75*
    52# 70 82 52
 
164         
46# 38 155 112 115*
    53# 48 186 117
 
205         
39# 28 108 92 87*
    39# 13 96 82
 
256         
53# 30 127 80 83*
    46# 31 118 86
 
320         
    12# 2 33 92
 
400         
   
Positive Control 3-Methylcholanthrene
5         
57 85 387 226 221*
    54 83 348 216

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