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Study Information
Study Attribute Value
CEBS Accession Number: 002-01568-0001-0000-3
Chemical Name: 8-Methoxypsoralen
CASRN: 298-81-7
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 421568_SCE
Study Result: Positive

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

Trial #: 1    Activation: No Activation    Date: 12/23/1986    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         
 50 1046 413 0.395 8.26 25.7 0.000
Test Chemical 8-Methoxypsoralen 
3.3       
 50 1048 593 0.566 11.86 25.7 43.310 
10         
 50 1034 581 0.562 11.62 25.7 42.311 
33.3       
 50 1028 1207 1.174 24.14 25.7 197.369 
100         
 9 189 259 1.370 28.78 25.7 247.072 
333.3       
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.001     
 50 1046 877 0.838 17.54 25.7 112.349
Mitomycin-C 
 0.01      
 5 106 230 2.170 46.00 25.7 449.545
Trend: 23.006        
Probability: 0.000        

Trial #: 2    Activation: No Activation    Date: 02/04/1987    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         
 25 526 167 0.317 6.68 25.7 0.000
Test Chemical 8-Methoxypsoralen 
20.2       
 25 515 387 0.751 15.48 25.7 136.686 
50.5       
 25 515 410 0.796 16.40 25.7 150.753 
100.5       
 5 103 101 0.981 20.20 25.7 208.854 
150         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.001     
 25 519 284 0.547 11.36 25.7 72.354
Mitomycin-C 
 0.01      
 5 104 198 1.904 39.60 25.7 499.655
Trend: 10.195        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 12/23/1986    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         
 50 1047 391 0.373 7.82 25.7 0.000
Test Chemical 8-Methoxypsoralen 
33.3       
 50 1044 553 0.530 11.06 25.7 41.839 
100         
 50 1047 611 0.584 12.22 25.7 56.266 
333.3       
 50 1046 910 0.870 18.20 25.7 132.959 
1000         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.4       
 50 1036 644 0.622 12.88 25.7 66.455
Cyclophosphamide 
2         
 5 104 180 1.731 36.00 25.7 363.457
Trend: 14.618        
Probability: 0.000