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Study Information
Study Attribute Value
CEBS Accession Number: 002-01525-0002-0000-7
Chemical Name: 5,5-Diphenylhydantoin (phenytoin)
CASRN: 57-41-0
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 335957_CA
Study Result: Negative

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

Trial #:1   Activation: No Activation    Date: 08/13/1981    Harvest Time: 14 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: Dimethyl Sulfoxide 
0         
 100 2 0.020 2.0 0 0.000 0.0 2 0.020 2.0 0 0.000 0.0
Test Chemical: 5,5-Diphenylhydantoin (phenytoin) 
500         
 100 3 0.030 3.0 1 0.010 1.0 2 0.020 2.0 0 0.000 0.0 
1600         
 100 2 0.020 2.0 0 0.000 0.0 2 0.020 2.0 0 0.000 0.0 
5000         
 100 2 0.020 2.0 1 0.010 1.0 1 0.010 1.0 0 0.000 0.0
Positive Control: Triethylenemelamine 
 0.15      
 100 31 0.310 24.0 10 0.100 9.0 21 0.210 19.0 0 0.000 0.0
Trend: -0.151 0.630 -0.510  
Probability: 0.560 0.264 0.695  


Trial #:1_S9   Activation: Induced Rat Liver S9    Date: 09/10/1981    Harvest Time: 14 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: Dimethyl Sulfoxide 
0         
 100 3 0.030 3.0 1 0.010 1.0 2 0.020 2.0 0 0.000 0.0
Test Chemical: 5,5-Diphenylhydantoin (phenytoin) 
125         
 100 4 0.040 4.0 1 0.010 1.0 3 0.030 3.0 0 0.000 0.0 
250         
 100 7 0.070 6.0 1 0.010 1.0 6 0.060 5.0 0 0.000 0.0 
2500         
 100 2 0.020 2.0 0 0.000 0.0 2 0.020 2.0 0 0.000 0.0 
5000         
 100 2 0.020 2.0 0 0.000 0.0 2 0.020 2.0 0 0.000 0.0
Positive Control: Cyclophosphamide 
15         
 100 20 0.200 18.0 11 0.110 11.0 9 0.090 8.0 0 0.000 0.0
Trend: -0.945 -1.326 -0.417  
Probability: 0.828 0.908 0.662  


Trial #:2_S9   Activation: Induced Rat Liver S9    Date: 08/13/1981    Harvest Time: 14 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: Dimethyl Sulfoxide 
0         
 100 3 0.030 3.0 0 0.000 0.0 3 0.030 3.0 0 0.000 0.0
Test Chemical: 5,5-Diphenylhydantoin (phenytoin) 
16         
 100 5 0.050 5.0 2 0.020 2.0 3 0.030 3.0 0 0.000 0.0 
50         
 100 8 0.080 7.0 1 0.010 1.0 7 0.070 6.0 0 0.000 0.0 
160         
 100 8 0.080 8.0 1 0.010 1.0 7 0.070 7.0 0 0.000 0.0
Positive Control: Cyclophosphamide 
15         
 100 33 0.330 30.0 14 0.140 14.0 19 0.190 18.0 0 0.000 0.0
Trend: 1.632 0.450 1.576  
Probability: 0.051 0.326 0.058