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Study Information
Study Attribute Value
CEBS Accession Number: 002-01389-0014-0000-8
Chemical Name: 3,3'-Dimethoxybenzidine dihydrochloride
CASRN: 20325-40-0
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 948661
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: Equivocal
  Conc.
ug/mL
Cloning
Efficiency
Relative Total
Growth
Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Solvent
 0         
97 93 60 21 25
    93 105 83 30
    80 97 65 27
    91 104 64 24
Test Chemical 3,3'-Dimethoxybenzidine dihydrochloride
40         
75 56 49 22 20
    57 84 26 15
    75 62 55 24
 
50         
86 58 48 19 19
    53# 49 27 17
    90 76 55 20
 
60         
79 56 48 20 19
    70# 49 30 14
    62 54 41 22
 
70         
62 26 47 25 29
    63 25 63 33
 
80         
56 13 54 32 35
    52# 10 66 42
    48 10 45 32
 
90         
51 6 71 46 43*
    63 10 56 29
    55 8 86 52
Positive Control Ethyl Methane Sulfonate
500         
27 11 660 810 953*
    34 18 908 886
    20 9 680 1162

Nonactivation Trial: 2 Experiment Call: Positive
  Conc.
ug/mL
Cloning
Efficiency
Relative Total
Growth
Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Solvent
 0         
84 109 67 27 27
    94 91 77 27
    165r 178 54 11
    125r 150 51 14
Test Chemical 3,3'-Dimethoxybenzidine dihydrochloride
40         
61 58 42 23 28
    90 54 91 34
    83 90 69 28
 
50         
87 59 47 18 29
    51 32 65 43
    70 60 57 27
 
60         
96 32 120 42 61*
    73 28 119 55
    42 7 108 85
 
70         
59 10 131 74 74*
    59 16 116 66
    70 10 176 84
 
80         
50# 13 92 61 72*
    74 12 139 63
    53 7 146 92
Positive Control Ethyl Methane Sulfonate
250         
79 69 743 314 283*
    109 77 761 233
    89# 70 807 303

Nonactivation Trial: 3 Experiment Call: Positive
  Conc.
ug/mL
Cloning
Efficiency
Relative Total
Growth
Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Solvent
 0         
9r 9 37.5 134 13
    85 107 25 10
    71 93 33 16
Test Chemical 3,3'-Dimethoxybenzidine dihydrochloride
40         
82 48 35 14 14
    91 60 30 11
    82 54 42 17
 
50         
70 29 38 18 17
    72# 34 36 17
    68 48 31 15
 
60         
61 20 48 26 22
    76 26 40 17
 
70         
58 3 136 78 59*
    78# 8 94.5 40
 
80         
   
    68 5 101 50
 
90         
   
   
Positive Control Ethyl Methane Sulfonate
250         
60 61 617 346 674*
    20 16 781 1302
    55 47 622 375

Nonactivation Trial: 4 Experiment Call: Positive
  Conc.
ug/mL
Cloning
Efficiency
Relative Total
Growth
Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Water
 0         
103 90 53 17 22
    94 98 70 25
    96 103 72 25
    88 110 60 23
Test Chemical 3,3'-Dimethoxybenzidine dihydrochloride
40         
83 70 62 25 26
    100 74 45 15
    53 47 62 39
 
50         
97 59 75 26 22
    85 64 41 16
    92 77 65 24
 
60         
75 43 75 33 37*
    77 26 104 45
    94 44 89 32
 
70         
93 45 94 34 30
    81 38 72 30
    70 45 54 26
 
80         
52 7 96 62 61*
    49 5 99 67
    71 9 116 54
 
90         
37 2 85 76 66*
    43 4 101 79
    60 14 76 42
Positive Control Ethyl Methane Sulfonate
250         
64 55 842 439 380*
    80 57 808 339
    80 64 868 363

Induced S9 Trial: 1 Experiment Call: Positive
  Conc.
ug/mL
Cloning
Efficiency
Relative Total
Growth
Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Solvent
 0         
82 97 95 39 36
    86 105 76 30
    92 88 115 42
    102 110 103 34
Test Chemical 3,3'-Dimethoxybenzidine dihydrochloride
4.7       
98 103 120 41 36
    87 86 80 31
 
9.4       
85 95 108 42 39
    87 85 93 36
 
18.8       
63 77 84 44 48
    86 81 133 52
 
37.5       
91 90 126 46 46
    90 103 122 45
 
75         
65 73 130 66 63*
    87 105 157 60
 
150         
118 90 149 42 64*
    79 75 203 85
Positive Control 3-Methylcholanthrene
5         
24 2 256 353 338*
    30 3 277 304
    25 2 267 356

Induced S9 Trial: 2 Experiment Call: Positive
  Conc.
ug/mL
Cloning
Efficiency
Relative Total
Growth
Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Solvent
 0         
89 113 87 33 29
    70 114 69 33
    87 91 51 19
    70 82 62 30
Test Chemical 3,3'-Dimethoxybenzidine dihydrochloride
100         
65 74 102 52 55*
    62 61 102 55
    70 71 121 58
 
125         
52 83 71 46 53*
    57 76 88 52
    55 70 101 62
 
150         
67 66 104 52 49*
    68 62 126 62
    54 62 53 33
 
200         
63 56 90 48 45*
    89 32 118 44
    62 58 79 42
 
250         
76 64 143 63 62*
    60 70 100 56
    54 48 107 66
Positive Control 3-Methylcholanthrene
5         
23 5 167 244 272*
    24 4 203 282
    26 4 224 289

Induced S9 Trial: 3 Experiment Call: Positive
  Conc.
ug/mL
Cloning
Efficiency
Relative Total
Growth
Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Solvent
 0         
93 107 57 20 17
    77 130 38 16
    76 89 25 11
    72 73 41 19
Test Chemical 3,3'-Dimethoxybenzidine dihydrochloride
50         
72 67 79 37 33*
    78 80 80 34
    74# 96 60 27
 
100         
69# 59 94.5 46 37*
    82 50 72 29
    63# 66 66 35
 
150         
87 95 92 35 37*
    93 70 120 43
    63 72 62 33
 
200         
61 57 84 46 36*
    50 64 56 37
    86 90 67 26
 
250         
66 80 60 30 37*
    65 74 73 38
    56 45 71 42
 
300         
52 29 57 36 32*
    60 63 46 25
    64 44 69 36
    60 47 58 32
Positive Control 3-Methylcholanthrene
2.5       
54 44 299 183 188*
    69 41 405 196
    61# 52 342 186

Induced S9 Trial: 4 Experiment Call: Positive
  Conc.
ug/mL
Cloning
Efficiency
Relative Total
Growth
Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Water
 0         
94 83 99 35 34
    133r 113 114 29
    108 112 101 31
    110 105 115 35
Test Chemical 3,3'-Dimethoxybenzidine dihydrochloride
50         
98 94 164 56 60*
    96 89 168 58
    103 73 204 66
 
100         
130r 97 203 52 59*
    113# 100 193.5 57
    96 71 176 61
 
200         
80 42 171 71
 
250         
128r 98 187 49 62*
    109# 77 234 71
    118 82 189 53
 
300         
85# 65 217.5 86 82*
    98 57 235 80
    104# 59 253.5 81
 
400         
132*
    72 10 365 169
    82 13 232 95
 
500         
   
   
Positive Control 3-Methylcholanthrene
2.5       
85 17 628 247 440*
    34 4 398 394
    27# 3 546 678

Induced S9 Trial: 5 Experiment Call: Positive
  Conc.
ug/mL
Cloning
Efficiency
Relative Total
Growth
Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Water
 0         
87# 96 75 29 29
    110 124 63 19
    97 93 91 31
    78# 87 85.5 37
Test Chemical 3,3'-Dimethoxybenzidine dihydrochloride
50         
90 87 183 68 62*
    97 90 150 51
    95 92 186 66
 
100         
84 97 149 59 66*
    90 93 184 69
    74 76 155 70
 
200         
102 103 176 58 67*
    90 71 204 76
    120r 104 169 47
 
250         
101 79 162 53 58*
    96 75 162 56
    92 63 181 66
 
300         
90 48 149 55 64*
    63 46 122 65
    64 57 138 72
    83 58 154 62
 
400         
102 30 237 78 100*
    52 12 195 126
    74 12 253 114
    72 18 176 82
Positive Control 3-Methylcholanthrene
2.5       
52 34 388 250 257*
    59 33 519 293
    64# 40 435 228

Induced S9 Trial: 6 Experiment Call: Positive
  Conc.
ug/mL
Cloning
Efficiency
Relative Total
Growth
Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Water
 0         
72# 71 52 24 20
    87 129 42 16
    87 96 55 21
    85 105 46 18
Test Chemical 3,3'-Dimethoxybenzidine dihydrochloride
50         
57# 64 63 37 35*
    60 74 67 37
    43 43 40 31
 
100         
69 50 110 54 48*
    53 60 83 52
    65 64 76 39
 
200         
45 50 69 51 52*
    51# 45 67 44
    43 45 78 60
 
250         
67 61 81 40 38*
    74 72 95 43
    90 70 81 30
 
300         
57 58 73 43 46*
    56 53 71 42
    75# 57 112.5 50
    57 60 84 49
 
400         
72 55 127 59 49*
    74 50 86 39
Positive Control 3-Methylcholanthrene
2.5       
76# 70 349.5 154 159*
    55# 55 282 171
    92 54 425 153

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