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Study Information
Study Attribute Value
CEBS Accession Number: 002-03029-0001-0000-7
Chemical Name: alpha-Methylstyrene
CASRN: 98-83-9
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 235924_SCE
Study Result: Positive

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

Trial #: 1    Activation: No Activation    Date: 05/05/1986    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 1050 351 0.334 7.02 25.5 0.000
Test Chemical alpha-Methylstyrene 
5         
 50 1049 340 0.324 6.80 25.5 -3.042 
16.7       
 50 1049 336 0.320 6.72 25.5 -4.182 
50         
 50 1050 359 0.342 7.18 25.5 2.279 
166.7       
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.001     
 50 1049 578 0.551 11.56 25.5 64.829
Mitomycin-C 
 0.01      
 5 104 200 1.923 40.00 25.5 475.279
Trend: 0.225        
Probability: 0.411        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 05/05/1986    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 1050 380 0.362 7.60 25.5 0.000
Test Chemical alpha-Methylstyrene 
5         
 50 1048 399 0.381 7.98 25.5 5.200 
16.7       
 50 1050 373 0.355 7.46 25.5 -1.842 
50         
 50 1050 488 0.465 9.76 25.5 28.421 
166.7       
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.4       
 50 1050 682 0.650 13.64 25.5 79.474
Cyclophosphamide 
2         
 5 104 153 1.471 30.60 25.5 306.503
Trend: 3.222        
Probability: 0.001        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 05/15/1986    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 25.2 0.000
Test Chemical alpha-Methylstyrene 
50         
 25 524 248 0.473 9.92 25.2 39.592 
124.4       
 25 524 265 0.506 10.60 25.2 49.161 
149.9       
 25 518 321 0.620 12.84 25.2 82.774
Positive Control Cyclophosphamide 
 0.4       
 25 522 344 0.659 13.76 25.2 94.369
Cyclophosphamide 
2         
 5 104 180 1.731 36.00 25.5 410.480
Trend: 6.054        
Probability: 0.000