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Study Information
Study Attribute Value
CEBS Accession Number: 002-02915-0001-0000-0
Chemical Name: Tolbutamide
CASRN: 64-77-7
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 481185_SCE
Study Result: Positive

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

Trial #: 1    Activation: No Activation    Date: 08/20/1985    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 1037 341 0.329 6.82 26.5 0.000
Test Chemical Tolbutamide 
50.5       
 50 1036 447 0.431 8.94 26.5 31.212 
151         
 50 1040 394 0.379 7.88 26.5 15.209 
504         
 50 1046 451 0.431 9.02 26.5 31.120
Positive Control Mitomycin-C 
 0.0015    
 50 1030 439 0.426 8.78 26.5 29.614
Mitomycin-C 
 0.01      
 10 209 209 1.000 20.90 26.5 204.106
Trend: 2.958        
Probability: 0.002        

Trial #: 2    Activation: No Activation    Date: 09/18/1985    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 1043 317 0.304 6.34 26.5 0.000
Test Chemical Tolbutamide 
92         
 50 1049 395 0.377 7.90 26.5 23.893 
368         
 50 1044 426 0.408 8.52 26.5 34.256 
460         
 50 1044 438 0.420 8.76 26.5 38.038 
690         
 50 1037 457 0.441 9.14 26.5 44.998 
966         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.002     
 50 1046 486 0.465 9.72 26.5 52.873
Mitomycin-C 
 0.01      
 10 210 204 0.971 20.40 26.5 219.621
Trend: 5.231        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 08/20/1985    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 1045 327 0.313 6.54 25.5 0.000
Test Chemical Tolbutamide 
50.5       
 50 1045 403 0.386 8.06 25.5 23.242 
151         
 50 1040 470 0.452 9.40 25.5 44.422 
504         
 50 1039 365 0.351 7.30 25.5 12.265
Positive Control Cyclophosphamide 
 0.5       
 50 1047 599 0.572 11.98 25.5 82.831
Cyclophosphamide 
2.5       
 10 210 279 1.329 27.90 25.5 324.574
Trend: 2.067        
Probability: 0.019