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Study Information
Study Attribute Value
CEBS Accession Number: 002-02269-0001-0000-2
Chemical Name: Hydroquinone
CASRN: 123-31-9
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 886668_SCE
Study Result: Positive

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

Trial #: 1    Activation: No Activation    Date: 02/23/1982    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 1019 374 0.367 7.48 25.5 0.000
Test Chemical Hydroquinone 
 0.5       
 50 1022 545 0.533 10.90 25.5 45.294 
1.67      
 50 1025 866 0.845 17.32 25.5 130.195 
5         
 50 1024 1013 0.989 20.26 25.5 169.533
Positive Control Mitomycin-C 
 0.005     
 25 515 817 1.586 32.68 25.5 332.232
Trend: 18.864        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 02/23/1982    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 1045 461 0.441 9.22 25.8 0.000
Test Chemical Hydroquinone 
50         
 50 1036 559 0.540 11.18 25.8 22.312 
167         
 50 1040 593 0.570 11.86 25.8 29.252 
500         
 50 1026 671 0.654 13.42 25.8 48.249 
1670         
 0 0 0 0.000 0.00 25.8 N/A
Positive Control Cyclophosphamide 
1.5       
 25 524 1032 1.969 41.28 25.8 346.441
Trend: 6.478        
Probability: 0.000        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 03/04/1982    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 1041 461 0.443 9.22 25.5 0.000
Test Chemical Hydroquinone 
600         
 50 1043 765 0.733 15.30 25.5 65.625 
700         
 50 1018 899 0.883 17.98 25.5 99.417 
800         
 50 1044 876 0.839 17.52 25.5 89.476
Positive Control Cyclophosphamide 
1.5       
 25 530 634 1.196 25.36 25.5 170.124
Trend: 11.431        
Probability: 0.000