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Study Information
Study Attribute Value
CEBS Accession Number: 002-01179-0001-0000-1
Chemical Name: 2,3,7,8-Tetrachlorodibenzo-p-dioxin
CASRN: 1746-01-6
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 764904_SCE
Study Result: Negative

Study Result: Negative
Activation Trial Trial Call
No Activation  1  Negative 
No Activation  2   
No Activation  3   
No Activation  4  Negative 
Induced Rat Liver S9  1_S9  Negative 
Induced Rat Liver S9  2_S9  Negative 

Trial #: 1    Activation: No Activation    Date: 05/25/1982    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 Ethanol 
0         
 50 1031 422 0.409 8.44 25.5 0.000
Test Chemical 2,3,7,8-Tetrachlorodibenzo-p-dioxin 
 0.04      
 50 1059 432 0.408 8.64 25.5 -0.337 
 0.133     
 50 1067 454 0.425 9.08 25.5 3.953 
 0.4       
 50 1047 402 0.384 8.04 25.5 -6.195
Positive Control Mitomycin-C 
 0.005     
 25 520 722 1.388 28.88 25.5 239.219
Trend: -0.638        
Probability: 0.738        

Trial #: 2    Activation: No Activation    Date: 06/10/1982    Trial Call:   
  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 Ethanol 
0         
 50 1053 385 0.366 7.70 25.5 0.000
Test Chemical 2,3,7,8-Tetrachlorodibenzo-p-dioxin 
 0.4       
 50 1045 430 0.411 8.60 25.5 12.543 
 0.6       
 50 1033 429 0.415 8.58 25.5 13.586 
 0.6       
 50 1045 508 0.486 10.16 36.3 32.958 
 0.8       
 50 1045 563 0.539 11.26 36.3 47.353
Positive Control Mitomycin-C 
 0.005     
 25 524 762 1.454 30.48 25.5 297.733
Trend: 5.963        
Probability: 0.000        

Trial #: 3    Activation: No Activation    Date: 06/21/1982    Trial Call:   
  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 1044 401 0.384 8.02 25.5 0.000
Ethanol 
0         
 0 0 0 0.000 0.00 25.5 N/A
Test Chemical 2,3,7,8-Tetrachlorodibenzo-p-dioxin 
 0.6       
 50 1041 427 0.410 8.54 25.5 0.000 
 0.7       
 50 1046 545 0.521 10.90 33.5 0.000 
 0.8       
 50 1039 551 0.530 11.02 33.5 0.000
Positive Control Mitomycin-C 
 0.005     
 25 526 710 1.350 28.40 25.5 0.000
Trend: 4.002        
Probability: 0.000        

Trial #: 4    Activation: No Activation    Date: 06/30/1982    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 Ethanol 
0         
 50 1052 527 0.501 10.54 32.5 0.000
Negative (Not Specified) 
0         
 50 1059 400 0.378 8.00 25.8 -24.600
Test Chemical 2,3,7,8-Tetrachlorodibenzo-p-dioxin 
 0.6       
 50 1048 513 0.490 10.26 32.5 -2.285 
 0.7       
 50 1059 537 0.507 10.74 32.5 1.224 
 0.8       
 50 1045 597 0.571 11.94 32.5 14.042
Positive Control Mitomycin-C 
 0.005     
 25 517 705 1.364 28.20 25.8 172.210
Trend: 2.264        
Probability: 0.012        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 05/25/1982    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 Ethanol 
0         
 50 1038 625 0.602 12.50 25.5 0.000
Test Chemical 2,3,7,8-Tetrachlorodibenzo-p-dioxin 
 0.04      
 50 1034 580 0.561 11.60 25.5 -6.841 
 0.133     
 50 1045 552 0.528 11.04 25.5 -12.272 
 0.4       
 50 1042 582 0.559 11.64 25.5 -7.237
Positive Control Cyclophosphamide 
1.5       
 25 523 897 1.715 35.88 25.5 184.845
Trend: -1.593        
Probability: 0.944        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 06/10/1982    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 Ethanol 
0         
 50 1043 534 0.512 10.68 25.5 0.000
Test Chemical 2,3,7,8-Tetrachlorodibenzo-p-dioxin 
 0.4       
 50 1037 525 0.506 10.50 25.5 -1.117 
 0.6       
 50 1035 569 0.550 11.38 25.5 7.378 
 0.8       
 50 1045 530 0.507 10.60 25.5 -0.939
Positive Control Cyclophosphamide 
1.5       
 25 526 834 1.586 33.36 25.5 209.687
Trend: 0.385        
Probability: 0.350