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Study Information
Study Attribute Value
CEBS Accession Number: 002-02579-0001-0000-6
Chemical Name: Naphthalene
CASRN: 91-20-3
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 040612_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  Questionable 
Induced Rat Liver S9  2_S9  Positive 

Trial #: 1    Activation: No Activation    Date: 09/22/1987    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 1046 388 0.371 7.76 25.8 0.000
Test Chemical Naphthalene 
9         
 50 1048 406 0.387 8.12 25.8 4.439 
27         
 50 1041 442 0.425 8.84 25.8 14.465 
90         
 50 1042 578 0.555 11.56 30.9 49.541 
270         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.001     
 50 1049 597 0.569 11.94 25.8 53.426
Mitomycin-C 
 0.01      
 5 105 217 2.067 43.40 25.8 457.148
Trend: 6.497        
Probability: 0.000        

Trial #: 2    Activation: No Activation    Date: 10/21/1987    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         
 25 525 178 0.339 7.12 25.8 0.000
Test Chemical Naphthalene 
27         
 25 525 222 0.423 8.88 25.8 24.719 
45         
 25 525 268 0.510 10.72 25.8 50.562 
90         
 25 525 268 0.510 10.72 25.8 50.562
Positive Control Mitomycin-C 
 0.001     
 25 525 376 0.716 15.04 25.8 111.236
Mitomycin-C 
 0.01      
 5 105 263 2.505 52.60 25.8 638.764
Trend: 4.530        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 09/22/1987    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 Dimethyl Sulfoxide 
0         
 50 1050 423 0.403 8.46 25.8 0.000
Test Chemical Naphthalene 
2.7       
 50 1050 411 0.391 8.22 25.8 -2.837 
9         
 50 1050 493 0.470 9.86 25.8 16.548 
27         
 50 1045 505 0.483 10.10 30.9 19.957 
90         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.4       
 50 1050 792 0.754 15.84 25.8 87.234
Cyclophosphamide 
2         
 5 105 197 1.876 39.40 25.8 365.721
Trend: 3.509        
Probability: 0.000        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 10/21/1987    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         
 25 525 189 0.360 7.56 25.8 0.000
Test Chemical Naphthalene 
9         
 25 525 199 0.379 7.96 25.8 5.291 
15         
 25 525 239 0.455 9.56 25.8 26.455 
27         
 25 525 266 0.507 10.64 25.8 40.741 
45         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.4       
 25 525 334 0.636 13.36 25.8 76.720
Cyclophosphamide 
2         
 5 105 174 1.657 34.80 25.8 360.317
Trend: 4.054        
Probability: 0.000