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Study Information
Study Attribute Value
CEBS Accession Number: 002-01542-0001-0000-5
Chemical Name: 5-Methoxypsoralen
CASRN: 484-20-8
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 197424_SCE
Study Result: Positive

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

Trial #: 1    Activation: No Activation    Date: 10/10/1990    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 1042 389 0.373 7.78 26.0 0.000
Test Chemical 5-Methoxypsoralen 
16         
 50 1026 635 0.619 12.70 26.0 65.785 
50         
 50 1032 619 0.600 12.38 26.0 60.668 
160         
 50 1028 645 0.627 12.90 26.0 68.068 
500         
 50 1037 656 0.633 13.12 26.0 69.451
Positive Control Mitomycin-C 
 0.0E-4    
 50 1022 525 0.514 10.50 26.0 37.603
Mitomycin-C 
 0.005     
 10 211 341 1.616 34.10 26.0 332.902
Trend: 7.133        
Probability: 0.000        

Trial #: 2    Activation: No Activation    Date: 11/13/1990    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 1039 416 0.400 8.32 26.0 0.000
Test Chemical 5-Methoxypsoralen 
16         
 50 1044 708 0.678 14.16 26.0 69.377 
50         
 50 1045 624 0.597 12.48 26.0 49.139 
160         
 50 1042 624 0.599 12.48 26.0 49.568 
500         
 50 1048 648 0.618 12.96 26.0 54.432
Positive Control Mitomycin-C 
 0.0625    
 10 210 620 2.952 62.00 26.0 637.386
Mitomycin-C 
 0.25      
 10 208 800 3.846 80.00 26.0 860.614
Trend: 4.768        
Probability: 0.000        

Trial #: 3    Activation: No Activation    Date: 12/09/1990    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 367 0.351 7.34 26.0 0.000
Test Chemical 5-Methoxypsoralen 
16         
 50 1025 621 0.606 12.42 26.0 72.842 
50         
 50 1033 570 0.552 11.40 26.0 57.418 
160         
 50 1039 609 0.586 12.18 26.0 67.218 
500         
 50 1043 599 0.574 11.98 26.0 63.841
Positive Control Mitomycin-C 
 0.0E-4    
 50 1035 583 0.563 11.66 26.0 60.697
Mitomycin-C 
 0.005     
 10 209 292 1.397 29.20 26.0 298.582
Trend: 6.019        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 10/10/1990    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 408 0.390 8.16 26.0 0.000
Test Chemical 5-Methoxypsoralen 
160         
 50 1038 504 0.486 10.08 26.0 24.600 
500         
 50 1029 608 0.591 12.16 26.0 51.626 
1600         
 50 1040 624 0.600 12.48 26.0 53.971 
2500         
 50 1036 611 0.590 12.22 26.0 51.345
Positive Control Cyclophosphamide 
 0.15      
 50 1024 535 0.522 10.70 26.0 34.073
Cyclophosphamide 
 0.6       
 10 206 179 0.869 17.90 26.0 122.983
Trend: 7.469        
Probability: 0.000