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Study Information
Study Attribute Value
CEBS Accession Number: 002-02131-0001-0000-0
Chemical Name: Ethionamide
CASRN: 536-33-4
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 457178_SCE
Study Result: Negative

Study Result: Negative
Activation Trial Trial Call
No Activation  1  Negative 
Induced Rat Liver S9  1_S9  Weakly Positive 
Induced Rat Liver S9  2_S9  Negative 
Induced Rat Liver S9  3_S9  Negative 

Trial #: 1    Activation: No Activation    Date: 01/30/1986    Trial Call: Negative   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Dimethyl Sulfoxide 
0         
 50 1042 476 0.457 9.52 26.0 0.000
Test Chemical Ethionamide 
5         
 50 1041 418 0.402 8.36 26.0 -12.101 
16         
 50 1046 436 0.417 8.72 26.0 -8.754 
50         
 50 1043 498 0.477 9.96 26.0 4.522 
160         
 16 326 116 0.356 7.25 26.0 -22.107 
500         
 0 0 0 0.000 0.00 26.0 N/A
Positive Control Mitomycin-C 
 0.0E-4    
 50 1047 656 0.627 13.12 26.0 37.157
Mitomycin-C 
 0.005     
 10 210 351 1.671 35.10 26.0 265.888
Trend: -0.403        
Probability: 0.657        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 04/15/1986    Trial Call: Weakly Positive   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Dimethyl Sulfoxide 
0         
 50 1050 458 0.436 9.16 26.0 0.000
Test Chemical Ethionamide 
160         
 50 1049 449 0.428 8.98 26.0 -1.872 
500         
 50 1049 468 0.446 9.36 26.0 2.281 
1600         
 50 1049 571 0.544 11.42 26.0 24.791 
2500         
 50 1050 487 0.464 9.74 26.0 6.332
Positive Control Cyclophosphamide 
 0.1       
 50 1049 571 0.544 11.42 26.0 24.791
Cyclophosphamide 
 0.6       
 10 210 251 1.195 25.10 26.0 174.017
Trend: 2.960        
Probability: 0.002        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 07/01/1986    Trial Call: Negative   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Dimethyl Sulfoxide 
0         
 50 1044 464 0.444 9.28 26.0 0.000
Test Chemical Ethionamide 
1000         
 50 1046 547 0.523 10.94 26.0 17.663 
1600         
 0 0 0 0.000 0.00 26.0 N/A 
2000         
 50 1047 545 0.521 10.90 26.0 17.120
Positive Control Cyclophosphamide 
 0.15      
 50 1047 581 0.555 11.62 26.0 24.857
Cyclophosphamide 
 0.6       
 10 210 205 0.976 20.50 26.0 119.643
Trend: 2.138        
Probability: 0.016        

Trial #: 3_S9    Activation: Induced Rat Liver S9    Date: 06/28/1988    Trial Call: Negative   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Dimethyl Sulfoxide 
0         
 50 1040 451 0.434 9.02 26.0 0.000
Test Chemical Ethionamide 
1000         
 50 1045 447 0.428 8.94 26.0 -1.361 
1200         
 50 1033 459 0.444 9.18 26.0 2.463 
1400         
 50 1041 505 0.485 10.10 26.0 11.866
Positive Control Cyclophosphamide 
 0.15      
 50 1046 581 0.555 11.62 26.0 28.086
Cyclophosphamide 
 0.6       
 10 210 196 0.933 19.60 26.0 115.225
Trend: 1.822        
Probability: 0.034