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Study Information
Study Attribute Value
CEBS Accession Number: 002-01176-0001-0000-8
Chemical Name: 2,3,5,6-Tetrachlorophenol
CASRN: 935-95-5
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 707071_SCE
Study Result: Positive

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

Trial #: 1    Activation: No Activation    Date: 12/05/1985    Trial Call: 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 1018 386 0.379 7.72 25.5 0.000
Test Chemical 2,3,5,6-Tetrachlorophenol 
 0.5       
 50 1010 402 0.398 8.04 31.0 4.970 
1.7       
 50 1006 481 0.478 9.62 31.0 26.098 
5         
 50 1002 456 0.455 9.12 31.0 20.021 
16.7       
 0 0 0 0.000 0.00 31.0 N/A
Positive Control Mitomycin-C 
 0.001     
 50 1021 606 0.594 12.12 25.5 56.534
Mitomycin-C 
 0.01      
 5 102 174 1.706 34.80 25.5 349.893
Trend: 3.397        
Probability: 0.000        

Trial #: 2    Activation: No Activation    Date: 12/15/1985    Trial Call: 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 1015 378 0.372 7.56 25.3 0.000
Test Chemical 2,3,5,6-Tetrachlorophenol 
5         
 50 1024 405 0.396 8.10 25.3 6.201 
10         
 50 1023 478 0.467 9.56 32.2 25.466 
15.1       
 50 1030 467 0.453 9.34 32.2 21.746 
20.4       
 0 0 0 0.000 0.00 32.2 N/A
Positive Control Mitomycin-C 
 0.001     
 50 1018 522 0.513 10.44 25.3 37.688
Mitomycin-C 
 0.01      
 5 103 184 1.786 36.80 25.3 379.684
Trend: 3.601        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 12/05/1985    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 1020 391 0.383 7.82 25.5 0.000
Test Chemical 2,3,5,6-Tetrachlorophenol 
16.7       
 50 1013 445 0.439 8.90 25.5 14.597 
50         
 50 1010 393 0.389 7.86 25.5 1.507 
166.7       
 50 1021 496 0.486 9.92 31.0 26.730 
500         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.4       
 50 1005 594 0.591 11.88 25.5 54.186
Cyclophosphamide 
2         
 5 104 244 2.346 48.80 25.5 512.040
Trend: 2.875        
Probability: 0.002        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 12/17/1985    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 1016 389 0.383 7.78 25.5 0.000
Test Chemical 2,3,5,6-Tetrachlorophenol 
75.4       
 50 1025 466 0.455 9.32 31.0 18.742 
150.8       
 50 1024 395 0.386 7.90 31.0 0.749 
225         
 50 1023 496 0.485 9.92 31.0 26.634 
300         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.4       
 50 1032 590 0.572 11.80 25.5 49.319
Cyclophosphamide 
2         
 5 102 188 1.843 37.60 25.5 381.395
Trend: 2.226        
Probability: 0.013