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Study Information
Study Attribute Value
CEBS Accession Number: 002-02417-0001-0000-7
Chemical Name: Methapyrilene hydrochloride
CASRN: 135-23-9
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 184622_SCE
Study Result: Positive

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

Trial #: 1    Activation: No Activation    Date: 07/13/1983    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 Medium 
0         
 50 1032 442 0.428 8.84 25.8 0.000
Test Chemical Methapyrilene hydrochloride 
50         
 50 1033 466 0.451 9.32 25.8 5.328 
166.7       
 50 1031 595 0.577 11.90 35.5 34.746 
500         
 0 0 0 0.000 0.00 35.5 N/A
Positive Control Mitomycin-C 
 0.01      
 5 103 215 2.087 43.00 25.8 387.370
Trend: 4.875        
Probability: 0.000        

Trial #: 2    Activation: No Activation    Date: 07/25/1983    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 Medium 
0         
 50 1046 483 0.462 9.66 25.8 0.000
Test Chemical Methapyrilene hydrochloride 
125.6       
 50 1030 476 0.462 9.52 25.8 0.082 
150.8       
 50 1024 567 0.554 11.34 25.8 19.913 
174.4       
 50 1037 596 0.575 11.92 31.3 24.466 
201         
 0 0 0 0.000 0.00 31.3 N/A
Positive Control Mitomycin-C 
 0.001     
 50 1032 627 0.608 12.54 25.8 31.575
Mitomycin-C 
 0.01      
 5 103 217 2.107 43.40 25.8 356.254
Trend: 4.378        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 07/13/1983    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 Medium 
0         
 50 1036 451 0.435 9.02 25.8 0.000
Test Chemical Methapyrilene hydrochloride 
166.7       
 50 1029 481 0.467 9.62 25.8 7.377 
500         
 50 1028 461 0.448 9.22 25.8 3.013 
1700         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
2         
 5 102 217 2.127 43.40 25.8 388.700
Trend: 0.462        
Probability: 0.322        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 07/25/1983    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 Medium 
0         
 50 1018 466 0.458 9.32 25.8 0.000
Test Chemical Methapyrilene hydrochloride 
597.8       
 50 1032 564 0.547 11.28 31.3 19.388 
696.4       
 50 1016 563 0.554 11.26 31.3 21.053 
797         
 50 1027 586 0.571 11.72 31.3 24.649 
904.4       
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.3       
 50 1030 697 0.677 13.94 25.8 47.828
Cyclophosphamide 
2         
 5 105 178 1.695 35.60 25.8 270.333
Trend: 3.371        
Probability: 0.000        

Trial #: 3_S9    Activation: Induced Rat Liver S9    Date: 08/02/1983    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 Medium 
0         
 50 1042 517 0.496 10.34 26.0 0.000
Test Chemical Methapyrilene hydrochloride 
800         
 50 1028 553 0.538 11.06 31.0 8.420 
850         
 50 1025 617 0.602 12.34 31.0 21.322 
900         
 50 1026 614 0.598 12.28 31.0 20.614
Positive Control Cyclophosphamide 
 0.3       
 50 1037 623 0.601 12.46 26.0 21.084
Cyclophosphamide 
2         
 5 104 172 1.654 34.40 26.0 233.328
Trend: 3.584        
Probability: 0.000