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Study Information
Study Attribute Value
CEBS Accession Number: 002-01341-0001-0000-2
Chemical Name: 2-Mercaptobenzimidazole
CASRN: 583-39-1
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 550909_SCE
Study Result: Positive

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

Trial #: 1    Activation: No Activation    Date: 04/03/1984    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 1036 580 0.560 11.60 26.3 0.000
Test Chemical 2-Mercaptobenzimidazole 
5         
 50 1034 576 0.557 11.52 26.3 -0.498 
16.7       
 50 1036 589 0.569 11.78 26.3 1.552 
50         
 50 1034 611 0.591 12.22 26.3 5.549 
167         
 50 1041 748 0.719 14.96 34.0 28.346 
500         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.0015    
 50 1039 792 0.762 15.84 26.3 36.157
Mitomycin-C 
 0.01      
 5 104 260 2.500 52.00 26.3 346.552
Trend: 4.641        
Probability: 0.000        

Trial #: 2    Activation: No Activation    Date: 06/19/1984    Trial Call: 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 1042 517 0.496 10.34 26.5 0.000
Test Chemical 2-Mercaptobenzimidazole 
150         
 50 1042 692 0.664 13.84 36.5 33.849 
200         
 50 1051 707 0.673 14.14 36.5 35.579 
250         
 50 1050 732 0.697 14.64 36.5 40.507 
300         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.0015    
 50 1048 739 0.705 14.78 26.5 42.122
Mitomycin-C 
 0.01      
 5 105 232 2.210 46.40 26.5 345.324
Trend: 5.493        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 04/03/1984    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 1037 579 0.558 11.58 26.3 0.000
Negative (Not Specified) 
0         
 50 1037 561 0.541 11.22 26.3 -3.109
Test Chemical 2-Mercaptobenzimidazole 
500         
 50 1037 614 0.592 12.28 26.3 6.045 
1670         
 50 1032 762 0.738 15.24 26.3 32.244 
5000         
 50 1034 660 0.638 13.20 26.3 14.320
Positive Control Cyclophosphamide 
 0.4       
 50 1034 759 0.734 15.18 26.3 31.468
Cyclophosphamide 
2         
 5 103 180 1.748 36.00 26.3 212.994
Trend: 3.570        
Probability: 0.000