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Study Information
Study Attribute Value
CEBS Accession Number: 002-02343-0001-0000-5
Chemical Name: L-Tryptophan
CASRN: 73-22-3
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 702434_SCE
Study Result: Negative

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

Trial #: 1    Activation: No Activation    Date: 01/30/1986    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 Medium 
0         
 50 1045 412 0.394 8.24 26.0 0.000
Test Chemical L-Tryptophan 
50         
 50 1046 411 0.393 8.22 26.0 -0.338 
160         
 50 1039 409 0.394 8.18 26.0 -0.155 
500         
 50 1043 436 0.418 8.72 26.0 6.028 
1000         
 50 1046 402 0.384 8.04 26.0 -2.520
Positive Control Mitomycin-C 
 0.0E-4    
 50 1047 656 0.627 13.12 26.0 58.919
Mitomycin-C 
 0.005     
 10 210 351 1.671 35.10 26.0 323.942
Trend: 0.176        
Probability: 0.430        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 04/08/1986    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 Medium 
0         
 50 1050 430 0.410 8.60 26.5 0.000
Test Chemical L-Tryptophan 
50         
 50 1050 441 0.420 8.82 26.5 2.558 
160         
 50 1050 441 0.420 8.82 26.5 2.558 
500         
 50 1050 475 0.452 9.50 26.5 10.465 
1000         
 50 1050 408 0.389 8.16 26.5 -5.116
Positive Control Cyclophosphamide 
 0.15      
 50 1049 620 0.591 12.40 26.0 44.323
Cyclophosphamide 
 0.6       
 10 210 235 1.119 23.50 26.5 173.256
Trend: 0.020        
Probability: 0.492