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Study Information
Study Attribute Value
CEBS Accession Number: 002-02482-0001-0000-9
Chemical Name: Mono(2-ethylhexyl)phthalate
CASRN: 4376-20-9
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 289374_SCE
Study Result: Weakly Positive

Study Result: Weakly Positive
Activation Trial Trial Call
No Activation  1  Questionable 
No Activation  2  Negative 
No Activation  3  Weakly Positive 
Induced Rat Liver S9  1_S9  Test Failure 
Induced Rat Liver S9  2_S9  Test Failure 

Trial #: 1    Activation: No Activation    Date: 05/14/1983    Trial Call: Questionable   
  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 Negative (Not Specified) 
0         
 50 1036 429 0.414 8.58 26.5 22.116
Dimethyl Sulfoxide 
0         
 50 1041 353 0.339 7.06 26.5 0.000
Test Chemical Mono(2-ethylhexyl)phthalate 
 0.5       
 50 1038 410 0.395 8.20 26.5 16.483 
1.6       
 50 1038 437 0.421 8.74 26.5 24.154 
16         
 50 1041 389 0.374 7.78 26.5 10.198 
50         
 0 0 0 0.000 0.00 26.5 N/A 
160         
 0 0 0 0.000 0.00 26.5 N/A
Positive Control Mitomycin-C 
 0.003     
 50 1040 1285 1.236 25.70 26.5 264.373
Mitomycin-C 
 0.005     
 50 1033 1623 1.571 32.46 26.5 363.334
Trend: 1.130        
Probability: 0.129        

Trial #: 2    Activation: No Activation    Date: 06/04/1983    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 Negative (Not Specified) 
0         
 50 1042 399 0.383 7.98 28.0 -3.394
Dimethyl Sulfoxide 
0         
 50 1047 415 0.396 8.30 28.0 0.000
Test Chemical Mono(2-ethylhexyl)phthalate 
10         
 50 1036 447 0.431 8.94 28.0 8.854 
25         
 50 1037 394 0.380 7.88 28.0 -4.145 
50         
 50 1033 444 0.430 8.88 28.0 8.438 
75         
 50 1027 438 0.426 8.76 28.0 7.598
Positive Control Mitomycin-C 
 0.003     
 50 1041 913 0.877 18.26 28.0 121.268
Mitomycin-C 
 0.005     
 50 1028 1216 1.183 24.32 28.0 198.428
Trend: 0.808        
Probability: 0.210        

Trial #: 3    Activation: No Activation    Date: 06/04/1983    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 1047 415 0.396 8.30 28.0 0.000
Negative (Not Specified) 
0         
 50 1042 399 0.383 7.98 28.0 -3.394
Test Chemical Mono(2-ethylhexyl)phthalate 
50         
 50 1024 474 0.463 9.48 31.0 16.782 
75         
 50 1031 476 0.462 9.52 31.0 16.479 
100         
 50 1036 523 0.505 10.46 31.0 27.362 
150         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.003     
 50 1041 913 0.877 18.26 28.0 121.268
Mitomycin-C 
 0.005     
 50 1028 1216 1.183 24.32 28.0 198.428
Trend: 3.436        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 05/14/1983    Trial Call: Test Failure   
  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 Negative (Not Specified) 
0         
 50 1044 418 0.400 8.36 26.0 -3.945
Dimethyl Sulfoxide 
0         
 50 1046 436 0.417 8.72 26.0 0.000
Test Chemical Mono(2-ethylhexyl)phthalate 
5         
 50 1047 394 0.376 7.88 26.0 -9.719 
16         
 50 1028 420 0.409 8.40 26.0 -1.983 
50         
 50 1037 448 0.432 8.96 26.0 3.644 
160         
 50 1028 437 0.425 8.74 26.0 1.984 
500         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
2         
 0 0 0 0.000 0.00 0.0 N/A
Trend: 1.146        
Probability: 0.126        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 06/04/1983    Trial Call: Test Failure   
  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 Negative (Not Specified) 
0         
 50 1036 430 0.415 8.60 28.0 8.716
Dimethyl Sulfoxide 
0         
 50 1032 394 0.382 7.88 28.0 0.000
Test Chemical Mono(2-ethylhexyl)phthalate 
100         
 50 1027 444 0.432 8.88 28.0 13.239 
200         
 0 0 0 0.000 0.00 0.0 N/A 
300         
 0 0 0 0.000 0.00 0.0 N/A 
400         
 0 0 0 0.000 0.00 0.0 N/A 
500         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
2         
 50 1040 1446 1.390 28.92 28.0 264.182
Trend: 1.798        
Probability: 0.036