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Study Information
Study Attribute Value
CEBS Accession Number: 002-02502-0001-0000-2
Chemical Name: N,N'-Dicyclohexylthiourea
CASRN: 1212-29-9
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 818765_SCE
Study Result: Positive

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

Trial #: 1    Activation: No Activation    Date: 08/25/1983    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 1043 415 0.398 8.30 26.0 10.129
Dimethyl Sulfoxide 
0         
 50 1049 379 0.361 7.58 26.0 0.000
Test Chemical N,N'-Dicyclohexylthiourea 
 0.5       
 50 1046 407 0.389 8.14 26.0 7.696 
1.6       
 50 1050 412 0.392 8.24 26.0 8.604 
50         
 50 1044 442 0.423 8.84 26.0 17.181 
160         
 50 1046 528 0.505 10.56 26.0 39.714 
500         
 50 1043 500 0.479 10.00 26.0 32.685 
700         
 50 1047 485 0.463 9.70 26.0 28.213 
1600         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.005     
 50 1050 1735 1.652 34.70 26.0 357.348
Trend: 5.875        
Probability: 0.000        

Trial #: 2    Activation: No Activation    Date: 11/15/1983    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 410 0.394 8.20 26.0 0.000
Negative (Not Specified) 
0         
 50 1047 396 0.378 7.92 26.0 -4.060
Test Chemical N,N'-Dicyclohexylthiourea 
 0.16      
 50 1037 457 0.441 9.14 26.0 11.786 
 0.5       
 50 1036 458 0.442 9.16 26.0 12.139 
1         
 50 1032 432 0.419 8.64 26.0 6.183 
5         
 50 1041 441 0.424 8.82 26.0 7.458 
50         
 50 1042 539 0.517 10.78 31.0 31.211
Positive Control Mitomycin-C 
 0.005     
 50 1052 1890 1.797 37.80 26.0 355.717
Trend: 3.616        
Probability: 0.000        

Trial #: 3    Activation: No Activation    Date: 12/14/1983    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 1046 380 0.363 7.60 26.0 -2.184
Dimethyl Sulfoxide 
0         
 50 1042 387 0.371 7.74 26.0 0.000
Test Chemical N,N'-Dicyclohexylthiourea 
5         
 50 1044 496 0.475 9.92 36.0 27.920 
10         
 50 1041 589 0.566 11.78 46.0 52.343 
16         
 0 0 0 0.000 0.00 0.0 N/A 
25         
 0 0 0 0.000 0.00 0.0 N/A 
50         
 50 1043 516 0.495 10.32 46.0 33.205
Positive Control Mitomycin-C 
 0.005     
 0 0 0 0.000 0.00 0.0 N/A
Trend: 3.549        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 11/15/1983    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 Negative (Not Specified) 
0         
 50 1048 404 0.385 8.08 26.0 -8.291
Dimethyl Sulfoxide 
0         
 50 1042 438 0.420 8.76 26.0 0.000
Test Chemical N,N'-Dicyclohexylthiourea 
50         
 50 1045 437 0.418 8.74 26.0 -0.515 
160         
 50 1030 449 0.436 8.98 26.0 3.706 
500         
 50 1018 450 0.442 9.00 26.0 5.162 
1000         
 50 1039 469 0.451 9.38 26.0 7.387
Positive Control Cyclophosphamide 
1.5       
 50 1050 3078 2.931 61.56 26.0 597.386
Trend: 1.332        
Probability: 0.091