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Study Information
Study Attribute Value
CEBS Accession Number: 002-02538-0001-0000-1
Chemical Name: N-Ethyl-N-nitrosourea
CASRN: 759-73-9
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 226054_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: 10/20/1987    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 1050 384 0.366 7.68 26.0 0.000
Test Chemical N-Ethyl-N-nitrosourea 
5         
 50 1049 567 0.541 11.34 26.0 47.797 
16         
 50 1050 731 0.696 14.62 26.0 90.365 
50         
 10 210 201 0.957 20.10 26.0 161.719 
160         
 10 210 302 1.438 30.20 26.0 293.229 
500         
 0 0 0 0.000 0.00 0.0 N/A 
1600         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.0E-4    
 50 1049 528 0.503 10.56 26.0 37.631
Mitomycin-C 
 0.005     
 10 211 291 1.379 29.10 26.0 277.110
Trend: 19.231        
Probability: 0.000        

Trial #: 2    Activation: No Activation    Date: 12/15/1987    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 1040 464 0.446 9.28 26.0 0.000
Test Chemical N-Ethyl-N-nitrosourea 
30         
 50 1045 1018 0.974 20.36 26.0 118.347 
50         
 10 210 265 1.262 26.50 26.0 182.841 
100         
 10 210 325 1.548 32.50 26.0 246.880 
160         
 10 212 406 1.915 40.60 26.0 329.245
Positive Control Mitomycin-C 
 0.0E-4    
 50 1045 559 0.535 11.18 26.0 19.898
Mitomycin-C 
 0.005     
 10 210 250 1.190 25.00 26.0 166.831
Trend: 24.224        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 10/20/1987    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 1051 359 0.342 7.18 26.0 0.000
Test Chemical N-Ethyl-N-nitrosourea 
16         
 50 1051 586 0.558 11.72 26.0 63.231 
50         
 50 1048 714 0.681 14.28 26.0 99.455 
160         
 10 211 210 0.995 21.00 26.0 191.370 
500         
 10 210 537 2.557 53.70 26.0 648.623 
1600         
 0 0 0 0.000 0.00 0.0 N/A 
5000         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.1       
 50 1051 439 0.418 8.78 26.0 22.284
Cyclophosphamide 
 0.6       
 10 210 208 0.990 20.80 26.0 189.969
Trend: 30.434        
Probability: 0.000