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Study Information
Study Attribute Value
CEBS Accession Number: 002-02418-0003-0000-0
Chemical Name: Methdilazine hydrochloride
CASRN: 1229-35-2
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 714394_SCE
Study Result: Equivocal

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

Trial #: 1    Activation: No Activation    Date: 09/21/1982    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 Water 
0         
 50 1029 518 0.503 10.36 25.7 0.000
Test Chemical Methdilazine hydrochloride 
 0.5       
 50 1022 440 0.431 8.80 25.7 -14.476 
1.67      
 50 1030 419 0.407 8.38 25.7 -19.191 
5         
 50 1035 388 0.375 7.76 25.7 -25.531 
16.7       
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.001     
 50 1033 678 0.656 13.56 25.7 30.381
Mitomycin-C 
 0.01      
 5 105 196 1.867 39.20 25.7 270.811
Trend: -4.494        
Probability: 1.000        

Trial #: 2    Activation: No Activation    Date: 09/29/1982    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 Water 
0         
 50 1035 403 0.389 8.06 25.5 0.000
Test Chemical Methdilazine hydrochloride 
17.4       
 50 1035 423 0.409 8.46 25.5 4.963 
20.2       
 50 1030 492 0.478 9.84 36.5 22.677 
25.2       
 50 1014 499 0.492 9.98 36.5 26.386
Positive Control Mitomycin-C 
 0.001     
 50 1038 657 0.633 13.14 25.5 62.556
Mitomycin-C 
 0.01      
 5 105 262 2.495 52.40 25.5 540.837
Trend: 3.984        
Probability: 0.000        

Trial #: 3    Activation: No Activation    Date: 11/03/1982    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 Water 
0         
 50 1018 396 0.389 7.92 25.5 0.000
Test Chemical Methdilazine hydrochloride 
12.5       
 50 1024 424 0.414 8.48 25.5 6.443 
15         
 50 1014 448 0.442 8.96 30.3 13.578 
17.4       
 0 0 0 0.000 0.00 30.3 N/A 
19.8       
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.001     
 50 1017 558 0.549 11.16 25.5 41.048
Mitomycin-C 
 0.01      
 5 103 205 1.990 41.00 25.5 411.646
Trend: 1.848        
Probability: 0.032        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 09/21/1982    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 Water 
0         
 50 1030 469 0.455 9.38 25.7 0.000
Test Chemical Methdilazine hydrochloride 
16.7       
 50 1033 461 0.446 9.22 25.7 -1.991 
50         
 0 0 0 0.000 0.00 0.0 N/A
Trend: -0.307        
Probability: 0.620        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 09/29/1982    Trial Call: Questionable   
  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 Water 
0         
 50 1045 406 0.389 8.12 25.5 0.000
Test Chemical Methdilazine hydrochloride 
15.1       
 50 1041 465 0.447 9.30 25.5 14.972 
20.1       
 50 1033 505 0.489 10.10 25.5 25.829 
30         
 50 1039 443 0.426 8.86 25.5 9.743 
40         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.3       
 50 1035 654 0.632 13.08 25.5 62.640
Cyclophosphamide 
2         
 5 104 210 2.019 42.00 25.5 419.728
Trend: 1.504        
Probability: 0.066        

Trial #: 3_S9    Activation: Induced Rat Liver S9    Date: 12/23/1982    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 Water 
0         
 50 1034 451 0.436 9.02 25.4 0.000
Test Chemical Methdilazine hydrochloride 
20.1       
 50 1040 409 0.393 8.18 25.4 -9.836 
24.9       
 50 1029 466 0.453 9.32 25.4 3.828 
30         
 50 1020 498 0.488 9.96 25.4 11.937 
35.1       
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.3       
 50 1028 615 0.598 12.30 25.4 37.160
Cyclophosphamide 
2         
 5 104 128 1.231 25.60 25.4 182.176
Trend: 2.362        
Probability: 0.009