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Study Information
Study Attribute Value
CEBS Accession Number: 002-02464-0001-0000-9
Chemical Name: Methylene blue trihydrate
CASRN: 7220-79-3
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 563848_SCE
Study Result: Positive

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

Trial #: 1    Activation: No Activation    Date: 03/12/1991    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 Water 
0         
 50 1048 365 0.348 7.30 26.0 0.000
Test Chemical Methylene blue trihydrate 
 0.17      
 50 1047 385 0.368 7.70 26.0 5.580 
 0.5       
 50 1050 406 0.387 8.12 26.0 11.021 
1.7       
 50 1047 445 0.425 8.90 26.0 22.034 
5         
 0 0 0 0.000 0.00 31.0 N/A
Positive Control Mitomycin-C 
 0.001     
 50 1050 514 0.490 10.28 26.0 40.554
Mitomycin-C 
 0.004     
 10 210 203 0.967 20.30 26.0 177.553
Trend: 2.930        
Probability: 0.002        

Trial #: 2    Activation: No Activation    Date: 04/24/1991    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 1049 344 0.328 6.88 26.0 0.000
Test Chemical Methylene blue trihydrate 
 0.63      
 50 1048 470 0.448 9.40 26.0 36.758 
1.3       
 50 1048 497 0.474 9.94 26.0 44.615 
2.5       
 50 1046 559 0.534 11.18 26.0 62.966 
5         
 0 0 0 0.000 0.00 31.0 N/A
Positive Control Mitomycin-C 
 0.001     
 50 1050 549 0.523 10.98 26.0 59.441
Mitomycin-C 
 0.004     
 10 210 243 1.157 24.30 26.0 252.861
Trend: 6.987        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 03/12/1991    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 Water 
0         
 50 1048 395 0.377 7.90 26.0 0.000
Water 
0         
 50 1050 412 0.392 8.24 31.0 4.105
Test Chemical Methylene blue trihydrate 
 0.5       
 50 1047 399 0.381 7.98 26.0 1.109 
1.7       
 50 1050 452 0.430 9.04 26.0 14.212 
5         
 50 1048 770 0.735 15.40 31.0 94.937 
17         
 0 0 0 0.000 0.00 31.0 N/A
Positive Control Cyclophosphamide 
 0.125     
 50 1050 479 0.456 9.58 26.0 21.035
Cyclophosphamide 
 0.5       
 10 210 199 0.948 19.90 26.0 151.419
Trend: 11.550        
Probability: 0.000