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Study Information
Study Attribute Value
CEBS Accession Number: 002-02663-0001-0000-0
Chemical Name: Phenazopyridine hydrochloride
CASRN: 136-40-3
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 693896_SCE
Study Result: Positive

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

Trial #: 1    Activation: No Activation    Date: 07/21/1982    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 Dimethyl Sulfoxide 
0         
 25 515 213 0.414 8.52 25.5 0.000
Test Chemical Phenazopyridine hydrochloride 
6         
 25 512 257 0.502 10.28 33.5 21.364 
20         
 0 0 0 0.000 0.00 0.0 N/A
Trend: 2.093        
Probability: 0.018        

Trial #: 2    Activation: No Activation    Date: 08/03/1982    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 1034 495 0.479 9.90 25.5 0.000
Test Chemical Phenazopyridine hydrochloride 
2.5       
 50 1024 525 0.513 10.50 25.5 7.096 
5         
 47 1014 524 0.517 11.15 25.5 7.947 
10         
 37 1024 647 0.632 17.49 34.5 31.984 
20         
 0 0 0 0.000 0.00 34.5 N/A
Positive Control Mitomycin-C 
 0.005     
 25 518 625 1.207 25.00 25.5 152.038
Trend: 4.521        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 07/21/1982    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 Dimethyl Sulfoxide 
0         
 25 519 195 0.376 7.80 25.5 0.000
Test Chemical Phenazopyridine hydrochloride 
60         
 25 513 222 0.433 8.88 25.5 15.178 
200         
 0 0 0 0.000 0.00 0.0 N/A
Trend: 1.441        
Probability: 0.075        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 08/03/1982    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 Dimethyl Sulfoxide 
0         
 50 1020 428 0.420 8.56 25.5 0.000
Test Chemical Phenazopyridine hydrochloride 
60         
 50 1030 561 0.545 11.22 32.6 29.802 
80         
 50 1002 530 0.529 10.60 32.6 26.056 
100         
 50 1013 601 0.593 12.02 32.6 41.391 
120         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
2         
 25 518 801 1.546 32.04 25.5 268.518
Trend: 4.886        
Probability: 0.000