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Study Information
Study Attribute Value
CEBS Accession Number: 002-02844-0001-0000-1
Chemical Name: Styrene
CASRN: 100-42-5
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 987609_SCE
Study Result: Negative

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

Trial #: 1    Activation: No Activation    Date: 07/15/1986    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 Dimethyl Sulfoxide 
0         
 50 1033 421 0.408 8.42 25.5 0.000
Test Chemical Styrene 
5         
 50 1017 462 0.454 9.24 25.5 11.465 
16.8       
 50 1006 444 0.441 8.88 25.5 8.294 
50.3       
 50 1020 459 0.450 9.18 25.5 10.416 
167.8       
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.001     
 50 1025 536 0.523 10.72 25.5 28.310
Mitomycin-C 
 0.01      
 5 101 229 2.267 45.80 25.5 456.330
Trend: 1.245        
Probability: 0.107        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 07/15/1986    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 1023 396 0.387 7.92 25.5 0.000
Test Chemical Styrene 
5         
 50 1026 421 0.410 8.42 25.5 6.002 
16.8       
 50 1022 481 0.471 9.62 25.5 21.583 
50.3       
 50 1008 446 0.442 8.92 25.5 14.302 
167.8       
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.4       
 50 1030 546 0.530 10.92 25.5 36.942
Cyclophosphamide 
2         
 5 106 173 1.632 34.60 25.5 321.619
Trend: 2.513        
Probability: 0.006        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 08/05/1986    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 Dimethyl Sulfoxide 
0         
 50 1027 465 0.453 9.30 25.8 0.000
Test Chemical Styrene 
16.1       
 50 1026 368 0.359 7.36 25.8 -20.783 
49.9       
 50 1028 443 0.431 8.86 25.8 -4.824 
99.7       
 50 1018 483 0.474 9.66 25.8 4.789 
151         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.4       
 5 104 285 2.740 57.00 25.8 505.242
Cyclophosphamide 
2         
 5 102 772 7.569 154.40 25.8 1571.609
Trend: 1.637        
Probability: 0.051        

Trial #: 3_S9    Activation: Induced Rat Liver S9    Date: 10/13/1987    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 Dimethyl Sulfoxide 
0         
 50 1050 309 0.294 6.18 25.5 0.000
Test Chemical Styrene 
4         
 50 1047 312 0.298 6.24 25.5 1.260 
8         
 50 1049 353 0.337 7.06 25.5 14.348 
16         
 50 1046 354 0.338 7.08 25.5 15.001 
33         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.4       
 50 1049 557 0.531 11.14 25.5 80.431
Cyclophosphamide 
2         
 5 105 199 1.895 39.80 25.5 544.013
Trend: 2.198        
Probability: 0.014