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Study Information
Study Attribute Value
CEBS Accession Number: 002-01073-0001-0000-4
Chemical Name: 1,3-Dichloro-5,5-dimethylhydantoin
CASRN: 118-52-5
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 807055_SCE
Study Result: Negative

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

Trial #: 1    Activation: No Activation    Date: 02/24/1982    Trial Call: Weakly 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 1049 432 0.412 8.64 26.0 0.000
Test Chemical 1,3-Dichloro-5,5-dimethylhydantoin 
 0.5       
 50 1049 400 0.381 8.00 26.0 -7.407 
1.6       
 50 1048 462 0.441 9.24 26.0 7.046 
5         
 50 1049 739 0.704 14.78 26.0 71.065 
16         
 50 1050 472 0.450 9.44 26.0 9.155
Positive Control Mitomycin-C 
 0.005     
 50 1047 810 0.774 16.20 26.0 87.858
Trend: 5.882        
Probability: 0.000        

Trial #: 2    Activation: No Activation    Date: 06/10/1982    Trial Call: Negative   
  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 405 0.387 8.10 26.0 0.000
Test Chemical 1,3-Dichloro-5,5-dimethylhydantoin 
4         
 50 1048 386 0.368 7.72 26.0 -4.782 
8         
 50 1046 407 0.389 8.14 26.0 0.590 
12         
 50 1040 429 0.413 8.58 26.0 6.639 
16         
 50 1050 412 0.392 8.24 26.0 1.438
Positive Control Mitomycin-C 
 0.005     
 25 523 565 1.080 22.60 26.0 179.279
Trend: 0.990        
Probability: 0.161        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 02/24/1982    Trial Call: Weakly 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 1044 600 0.575 12.00 26.0 0.000
Test Chemical 1,3-Dichloro-5,5-dimethylhydantoin 
 0.5       
 50 1049 533 0.508 10.66 26.0 -11.590 
1.6       
 50 1050 512 0.488 10.24 26.0 -15.154 
5         
 50 1051 523 0.498 10.46 26.0 -13.414 
16         
 50 1048 736 0.702 14.72 26.0 22.198
Positive Control Cyclophosphamide 
1         
 50 1048 729 0.696 14.58 26.0 21.036
Trend: 3.369        
Probability: 0.000        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 06/10/1982    Trial Call: Negative   
  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 1045 404 0.387 8.08 26.0 0.000
Test Chemical 1,3-Dichloro-5,5-dimethylhydantoin 
4         
 50 1050 361 0.344 7.22 26.0 -11.069 
8         
 50 1043 327 0.314 6.54 26.0 -18.904 
12         
 50 1047 352 0.336 7.04 26.0 -13.038 
16         
 50 1046 429 0.410 8.58 26.0 6.087
Positive Control Cyclophosphamide 
1.5       
 50 1049 1355 1.292 27.10 26.0 234.117
Trend: 0.148        
Probability: 0.441