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Study Information
Study Attribute Value
CEBS Accession Number: 002-01568-0002-0000-4
Chemical Name: 8-Methoxypsoralen
CASRN: 298-81-7
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 421568_CA
Study Result: Positive

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

Trial #:1   Activation: No Activation    Date: 03/05/1987    Harvest Time: 20 hour(s)   Trial Call: Positive   
  Dose
µg/mL		 Total
Cells Examined		 Total Aberrations Complex Aberrations Simple Aberrations Other Abs
No. of
Abs		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs
Vehicle Control: Dimethyl Sulfoxide 
0         
 200 3 0.015 1.5 1 0.005 0.5 2 0.010 1.0 0 0.000 0.0
Negative (Not Specified) 
0         
 200 1 0.005 0.5 1 0.005 0.5 0 0.000 0.0 0 0.000 0.0
Test Chemical: 8-Methoxypsoralen 
100         
 200 21 0.105 9.5 10 0.050 5.0 11 0.055 4.5 0 0.000 0.0 
150         
 200 22 0.110 10.5 8 0.040 4.0 14 0.070 7.0 0 0.000 0.0 
200         
 100 42 0.420 35.0 10 0.100 10.0 32 0.320 28.0 0 0.000 0.0
Positive Control: Mitomycin-C 
 0.05      
 200 39 0.195 14.5 11 0.055 5.0 28 0.140 10.5 0 0.000 0.0
Mitomycin-C 
 0.08      
 25 20 0.800 52.0 9 0.360 28.0 11 0.440 28.0 0 0.000 0.0
Trend: 7.380 3.321 7.058  
Probability: 0.000 0.000 0.000  


Trial #:1_S9   Activation: Induced Rat Liver S9    Date: 05/07/1987    Harvest Time: 12 hour(s)   Trial Call: Weakly Positive   
  Dose
µg/mL		 Total
Cells Examined		 Total Aberrations Complex Aberrations Simple Aberrations Other Abs
No. of
Abs		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs
Vehicle Control: Negative (Not Specified) 
0         
 100 1 0.010 1.0 0 0.000 0.0 1 0.010 1.0 0 0.000 0.0
Dimethyl Sulfoxide 
0         
 100 2 0.020 2.0 1 0.010 1.0 1 0.010 1.0 0 0.000 0.0
Test Chemical: 8-Methoxypsoralen 
498         
 100 9 0.090 8.0 7 0.070 7.0 2 0.020 2.0 0 0.000 0.0 
552         
 100 7 0.070 7.0 5 0.050 5.0 2 0.020 2.0 0 0.000 0.0 
600         
 100 9 0.090 9.0 6 0.060 6.0 3 0.030 3.0 0 0.000 0.0
Positive Control: Cyclophosphamide 
7.5       
 100 11 0.110 11.0 4 0.040 4.0 7 0.070 7.0 0 0.000 0.0
Cyclophosphamide 
37.5       
 25 11 0.440 32.0 3 0.120 12.0 8 0.320 28.0 0 0.000 0.0
Trend: 1.803 1.357 0.948  
Probability: 0.036 0.087 0.172  


Trial #:2   Activation: No Activation    Date: 04/30/1987    Harvest Time: 20.2 hour(s)   Trial Call: Positive   
  Dose
µg/mL		 Total
Cells Examined		 Total Aberrations Complex Aberrations Simple Aberrations Other Abs
No. of
Abs		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs
Vehicle Control: Negative (Not Specified) 
0         
 100 2 0.020 2.0 1 0.010 1.0 1 0.010 1.0 0 0.000 0.0
Dimethyl Sulfoxide 
0         
 100 1 0.010 1.0 0 0.000 0.0 1 0.010 1.0 0 0.000 0.0
Test Chemical: 8-Methoxypsoralen 
200         
 100 19 0.190 15.0 9 0.090 6.0 10 0.100 10.0 0 0.000 0.0 
225         
 100 15 0.150 15.0 4 0.040 4.0 11 0.110 11.0 0 0.000 0.0 
250         
 100 33 0.330 29.0 19 0.190 18.0 14 0.140 13.0 0 0.000 0.0
Positive Control: Mitomycin-C 
 0.05      
 100 34 0.340 26.0 23 0.230 20.0 11 0.110 10.0 0 0.000 0.0
Mitomycin-C 
 0.08      
 25 29 1.160 52.0 8 0.320 28.0 21 0.840 40.0 0 0.000 0.0
Trend: 5.230 4.502 2.931  
Probability: 0.000 0.000 0.002  


Trial #:2_S9   Activation: Induced Rat Liver S9    Date: 04/09/1987    Harvest Time: 12 hour(s)   Trial Call: Negative   
  Dose
µg/mL		 Total
Cells Examined		 Total Aberrations Complex Aberrations Simple Aberrations Other Abs
No. of
Abs		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs
Vehicle Control: Negative (Not Specified) 
0         
 200 3 0.015 1.5 1 0.005 0.5 2 0.010 1.0 0 0.000 0.0
Dimethyl Sulfoxide 
0         
 200 5 0.025 2.5 2 0.010 1.0 3 0.015 1.5 0 0.000 0.0
Test Chemical: 8-Methoxypsoralen 
101         
 200 6 0.030 3.0 3 0.015 1.5 3 0.015 1.5 0 0.000 0.0 
252         
 200 8 0.040 3.5 1 0.005 0.5 7 0.035 3.0 0 0.000 0.0 
502.5       
 200 14 0.070 6.5 6 0.030 3.0 8 0.040 4.0 0 0.000 0.0
Positive Control: Cyclophosphamide 
7.5       
 200 26 0.130 10.5 12 0.060 5.5 14 0.070 5.0 0 0.000 0.0
Cyclophosphamide 
37.5       
 25 14 0.560 44.0 6 0.240 24.0 8 0.320 24.0 0 0.000 0.0
Trend: 2.000 1.210 1.823  
Probability: 0.023 0.113 0.034