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Study Information
Study Attribute Value
CEBS Accession Number: 002-03142-0001-0000-3
Chemical Name: o-Toluidine
CASRN: 95-53-4
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 489590_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  Weakly Positive 
Induced Rat Liver S9  2_S9  Weakly Positive 

Trial #: 1    Activation: No Activation    Date: 11/12/1982    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 Negative (Not Specified) 
0         
 50 1047 446 0.426 8.92 26.0 -4.573
Dimethyl Sulfoxide 
0         
 50 1026 458 0.446 9.16 26.0 0.000
Test Chemical o-Toluidine 
1.6       
 50 1039 510 0.491 10.20 26.0 9.960 
5         
 50 1044 534 0.511 10.68 26.0 14.584 
16         
 50 1040 544 0.523 10.88 26.0 17.178 
50         
 50 1038 605 0.583 12.10 26.0 30.569 
160         
 50 1048 691 0.659 13.82 26.0 47.706 
500         
 0 0 0 0.000 0.00 26.0 N/A
Positive Control Mitomycin-C 
 0.01      
 50 1038 1996 1.923 39.92 26.0 330.770
Trend: 7.122        
Probability: 0.000        

Trial #: 2    Activation: No Activation    Date: 12/13/1982    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 1038 467 0.450 9.34 26.0 0.000
Negative (Not Specified) 
0         
 50 1034 374 0.362 7.48 26.0 -19.605
Test Chemical o-Toluidine 
25         
 50 1042 550 0.528 11.00 26.0 17.321 
50         
 50 1048 558 0.532 11.16 26.0 18.346 
100         
 50 1047 624 0.596 12.48 26.0 32.470 
250         
 50 1038 750 0.723 15.00 43.0 60.600 
500         
 50 1029 872 0.847 17.44 43.0 88.357 
750         
 0 0 0 0.000 0.00 43.0 N/A
Positive Control Mitomycin-C 
 0.01      
 50 1048 2694 2.571 53.88 26.0 471.369
Trend: 13.062        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 11/12/1982    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 1040 465 0.447 9.30 26.0 0.000
Negative (Not Specified) 
0         
 50 1044 441 0.422 8.82 26.0 -5.525
Test Chemical o-Toluidine 
16         
 50 1039 436 0.420 8.72 26.0 -6.146 
50         
 50 1045 445 0.426 8.90 26.0 -4.759 
160         
 50 1029 470 0.457 9.40 26.0 2.156 
500         
 50 1038 464 0.447 9.28 26.0 -0.023 
1600         
 50 1040 559 0.538 11.18 26.0 20.215 
5000         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
1.5       
 50 1047 1630 1.557 32.60 26.0 248.194
Trend: 3.235        
Probability: 0.001        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 12/13/1982    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 1046 439 0.420 8.78 26.0 0.000
Negative (Not Specified) 
0         
 50 1049 416 0.397 8.32 26.0 -5.510
Test Chemical o-Toluidine 
500         
 50 1046 481 0.460 9.62 26.0 9.567 
750         
 50 1038 521 0.502 10.42 26.0 19.593 
1000         
 50 1048 529 0.505 10.58 26.0 20.271 
1500         
 50 1048 527 0.503 10.54 26.0 19.816 
2000         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
2         
 50 1045 1868 1.788 37.36 26.0 325.920
Trend: 3.140        
Probability: 0.001