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Study Information
Study Attribute Value
CEBS Accession Number: 002-01525-0004-0000-9
Chemical Name: 5,5-Diphenylhydantoin (phenytoin)
CASRN: 57-41-0
NTP Study Type: Genetic Toxicology - Micronucleus
NTP Study ID: 252424
Strain and Species: B6C3F1 Mouse
Study Result: Male: Negative

Bone Marrow

Start Date Sample Collection Time Sex Methodology Used Route Dosing Regimen
1988-10-04 24 hour Male Slide Scoring Intraperitoneal Injection Intraperitoneal Injection x 3, 72 hour
  Dose
(mg/kg)		 Animal
Number		 Polychromatic Erythrocytes
Trend P: 0.171
No. Examined Total MN Cells Percent PCE MN Cells
per 1000
Vehicle Control Corn Oil 
 0         
 512 2000 3 60.0 1.5 
 0         
 514 2000 12 58.5 6.0 
 0         
 517 2000 5 43.0 2.5 
 0         
 519 2000 1 58.5 0.5 
 0         
 546 2000 2 60.0 1.0
Average ± SEM   56.000 ± 3.270 2.300 ± 0.980
 
Test Chemical 5,5-Diphenylhydantoin (phenytoin) 
17.5       
 502 2000 4 41.5 2.0 
17.5       
 513 2000 7 49.0 3.5 
17.5       
 515 2000 8 56.5 4.0 
17.5       
 531 2000 5 54.5 2.5 
17.5       
 537 2000 4 47.0 2.0
Average ± SEM   49.700 ± 2.690 2.800 ± 0.410
Pairwise P   0.327
 
Test Chemical 5,5-Diphenylhydantoin (phenytoin) 
35         
 504 2000 4 53.5 2.0 
35         
 525 0 0 0 0.0 
35         
 526 2000 6 52.0 3.0 
35         
 529 2000 7 58.0 3.5 
35         
 530 2000 12 40.5 6.0
Average ± SEM   51.000 ± 3.720 3.630 ± 0.850
Pairwise P   0.146
 
Test Chemical 5,5-Diphenylhydantoin (phenytoin) 
70         
 505 0 0 0 0.0 
70         
 506 2000 4 45.5 2.0 
70         
 516 2000 14 45.5 7.0 
70         
 522 2000 2 52.0 1.0 
70         
 528 2000 8 34.5 4.0 
70         
 535 2000 6 58.0 3.0
Average ± SEM   47.100 ± 3.920 3.400 ± 1.030
Pairwise P   0.175
 
Positive Control Dimethylbenzanthracene 
12.5       
 507 2000 13 43.0 6.5 
12.5       
 508 2000 20 47.5 10.0 
12.5       
 509 2000 18 47.0 9.0 
12.5       
 511 2000 12 30.5 6.0 
12.5       
 539 2000 10 27.0 5.0
Average ± SEM   39.000 ± 4.290 7.300 ± 0.940
Pairwise P   Value less than 0.0001
 

Blood

Start Date Sample Collection Time Sex Methodology Used Route Dosing Regimen
1988-10-04 24 hour Male Slide Scoring Intraperitoneal Injection Intraperitoneal Injection x 3, 72 hour
  Dose
(mg/kg)		 Animal
Number		 Polychromatic Erythrocytes
Trend P: 0.800
No. Examined Total MN Cells Percent PCE MN Cells
per 1000
Vehicle Control Corn Oil 
 0         
 512 2000 5 2.0 2.5 
 0         
 514 2000 7 2.8 3.5 
 0         
 517 2000 7 3.1 3.5 
 0         
 519 2000 7 2.9 3.5 
 0         
 546 2000 6 5.4 3.0
Average ± SEM   3.240 ± 0.570 3.200 ± 0.200
 
Test Chemical 5,5-Diphenylhydantoin (phenytoin) 
17.5       
 502 2000 8 4.2 4.0 
17.5       
 513 2000 5 3.1 2.5 
17.5       
 515 2000 7 4.5 3.5 
17.5       
 531 2000 7 3.7 3.5 
17.5       
 537 2000 5 2.7 2.5
Average ± SEM   3.640 ± 0.330 3.200 ± 0.300
Pairwise P   0.500
 
Test Chemical 5,5-Diphenylhydantoin (phenytoin) 
35         
 504 2000 4 3.0 2.0 
35         
 525 0 0 0 0.0 
35         
 526 2000 3 3.8 1.5 
35         
 529 2000 4 2.6 2.0 
35         
 530 2000 7 2.9 3.5
Average ± SEM   3.080 ± 0.260 2.250 ± 0.430
Pairwise P   0.886
 
Test Chemical 5,5-Diphenylhydantoin (phenytoin) 
70         
 505 0 0 0 0.0 
70         
 506 2000 8 3.6 4.0 
70         
 516 2000 4 3.1 2.0 
70         
 522 2000 7 4.0 3.5 
70         
 528 2000 4 4.4 2.0 
70         
 535 2000 4 3.0 2.0
Average ± SEM   3.620 ± 0.270 2.700 ± 0.440
Pairwise P   0.743
 
Positive Control Dimethylbenzanthracene 
12.5       
 507 2000 9 1.1 4.5 
12.5       
 508 2000 21 1.5 10.5 
12.5       
 509 2000 24 2.7 12.0 
12.5       
 511 2000 21 1.3 10.5 
12.5       
 539 2000 20 0.9 10.0
Average ± SEM   1.500 ± 0.320 9.500 ± 1.290
Pairwise P   Value less than 0.0001