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Study Information
Study Attribute Value
CEBS Accession Number: 002-02131-0008-0000-7
Chemical Name: Ethionamide
CASRN: 536-33-4
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 292497
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 Dimethyl Sulfoxide 
 0         
 116 91 121 35 33
    122r 96 160 44
    101 97 97 32
    120 112 119 33
Test Chemical Ethionamide 
25         
 106 84 112 35 30
    120 81 92 26
    113 74 102 30
  
50         
 112 86 125 37 35
    120r 94 120 33
    118 85 117 33
  
100         
 82 58 129 52 46
    114 80 133 39
    98 63 140 47
  
200         
 101 57 152 50 46
    114 52 175 51
    112 64 128 38
  
300         
 93 44 196 70 53*
    105 55 130 41
    105 60 149 47
  
500         
 119 30 261 73 91*
    64 11 237 123
    112 25 255 76
Positive Control Methyl Methane Sulfonate 
5         
 90 58 879 324 278*
    73 42 778 355
    83 61 386 154

Nonactivation Trial: 2 Experiment Call: Inconclusive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 104 96 101 32 32
    101 95 81 27
    109 102 114 35
    113 106 115 34
Test Chemical Ethionamide 
25         
 108 86 150 46 45
    119 108 146 41
    103 88 150 49
  
50         
 104 93 120 39 37
    104 84 114 37
    112# 99 120 36
  
100         
 91 76 93 34 36
    101 87 120 40
    104 78 102 33
  
200         
 96 61 147 51 41
    103 69 126 41
    96 68 92 32
  
300         
 110 62 120 37 39
    107 64 126 39
    105 60 131 42
  
500         
 77 44 114 50 50*
    97 57 146 50
    83 49 122 49
Positive Control Methyl Methane Sulfonate 
5         
 73 49 440 201 229*
    77 45 555 239
    66 46 492 247

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         
 58 91 144 83 66
    60 56 166 92
    80 133 122 51
    71 120 82 38
Test Chemical Ethionamide 
200         
 72 54 171 80 83
    71 47 144 68
    82 35 252 103
  
300         
 90 48 234 87 104*
    72 26 255 119
    59# 25 185 105
  
400         
 113 21 305 90 89
    73 22 230 106
    82 31 172 70
  
500         
 101 59 204 67 144*
    65 11 326 168
    59 8 344 195
  
600         
   
   
Positive Control Methyl Methane Sulfonate 
5         
 32 36 943 977 1014*
    29# 23 1061 1241
    40 37 978 825

Induced S9 Trial: 1 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 107 107 92 29 30
    103 124 92 30
    104 84 90 29
    100 85 104 35
Test Chemical Ethionamide 
100         
 124r 66 108 29 33
    112 82 95 28
    107# 71 121 38
  
200         
 99 80 101 34 32
    121r 79 126 35
    113 75 104 31
  
300         
 118 88 134 38 34
    104 76 75 24
    115 64 137 40
  
400         
 124r 68 145 39 44
    108 60 142 44
    106 67 140 44
  
600         
 104# 54 146 47 44
    121r 52 125 35
    99 57 125 42
  
800         
 111 33 101 30 28
    99 9 76 26
Positive Control 3-Methylcholanthrene 
2.5       
 79# 43 805 338 275*
    97 47 801 275
    114 46 723 212

Induced S9 Trial: 2 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 96 101 88 31 31
    86# 95 80 31
    72 90 62 29
    74 114 78 35
Test Chemical Ethionamide 
100         
 103 144 90 29 28
    137r 219 91 22
    98 158 80 27
  
200         
 121r 174 103 28
    94 143 97 34
    123r 146 92 25
  
300         
 120 117 63 18 28
    107 102 117 37
    105 108 91 29
  
400         
 112 73 109 32 33
    112 95 116 34
    122r 80 141 39
  
600         
 90 32 134 49 39
    97 39 86 30
    107 47 124 39
  
800         
 107 32 126 39 50*
    78 9 122 52
    100 14 170 57
Positive Control 3-Methylcholanthrene 
2.5       
 60 54 731 408 326*
    73 42 523 240
    67 56 661 328

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