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Study Information
Study Attribute Value
CEBS Accession Number: 002-01141-0001-0000-0
Chemical Name: 1-trans-delta-9-Tetrahydrocannabinol
CASRN: 1972-08-3
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 829547_SCE
Study Result: Weakly Positive

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

Trial #: 1    Activation: No Activation    Date: 09/27/1983    Trial Call: Test Failure   
  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 1047 515 0.492 10.30 25.5 0.000
Test Chemical 1-trans-delta-9-Tetrahydrocannabinol 
3         
 50 1044 513 0.491 10.26 25.5 -0.102 
10         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.0015    
 50 1055 677 0.642 13.54 25.5 30.459
Mitomycin-C 
 0.01      
 5 105 234 2.229 46.80 25.5 353.071
Trend: -0.016        
Probability: 0.507        

Trial #: 2    Activation: No Activation    Date: 10/11/1983    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 Dimethyl Sulfoxide 
0         
 50 1043 523 0.501 10.46 25.5 0.000
Test Chemical 1-trans-delta-9-Tetrahydrocannabinol 
6         
 50 1046 536 0.512 10.72 33.0 2.192 
8         
 50 1046 524 0.501 10.48 33.0 -0.096 
10         
 50 1045 534 0.511 10.68 33.0 1.908 
15         
 0 0 0 0.000 0.00 33.0 N/A 
20         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.0015    
 50 1045 723 0.692 14.46 25.5 37.976
Mitomycin-C 
 0.01      
 5 104 201 1.933 40.20 25.5 285.430
Trend: 0.167        
Probability: 0.434        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 10/11/1983    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 1043 496 0.476 9.92 25.5 0.000
Test Chemical 1-trans-delta-9-Tetrahydrocannabinol 
7.5       
 50 1045 472 0.452 9.44 25.5 -5.021 
10         
 50 1041 550 0.528 11.00 25.5 11.100 
12.5       
 50 1041 619 0.595 12.38 33.0 25.038 
15         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.4       
 50 1047 670 0.640 13.40 25.5 34.565
Cyclophosphamide 
2         
 5 103 186 1.806 37.20 25.5 279.733
Trend: 4.409        
Probability: 0.000        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 10/25/1983    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 1047 525 0.501 10.50 25.5 0.000
Test Chemical 1-trans-delta-9-Tetrahydrocannabinol 
7.5       
 50 1046 540 0.516 10.80 25.5 2.955 
10         
 50 1045 559 0.535 11.18 29.3 6.680 
12.5       
 50 1043 693 0.664 13.86 29.3 32.506 
15         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.4       
 50 1047 780 0.745 15.60 25.5 48.571
Cyclophosphamide 
2         
 50 104 213 2.048 4.26 25.5 308.445
Trend: 4.853        
Probability: 0.000