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Study Information
Study Attribute Value
CEBS Accession Number: 002-01873-0001-0000-2
Chemical Name: Chlorothalonil
CASRN: 1897-45-6
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 739007_SCE
Study Result: Positive

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

Trial #: 1    Activation: No Activation    Date: 08/02/1982    Trial Call:   
  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 1043 461 0.442 9.22 26.3 0.000
Test Chemical Chlorothalonil 
 0.25      
 50 1039 519 0.500 10.38 26.3 13.015
Positive Control Mitomycin-C 
 0.005     
 25 519 713 1.374 28.52 26.3 210.818
Trend: 0.000        
Probability: 0.000        

Trial #: 2    Activation: No Activation    Date: 09/14/1982    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 466 0.445 9.32 25.8 0.000
Test Chemical Chlorothalonil 
 0.4       
 50 1043 508 0.487 10.16 25.8 9.431 
 0.45      
 50 1041 513 0.493 10.26 25.8 10.720 
 0.5       
 50 1047 511 0.488 10.22 33.3 9.657
Positive Control Mitomycin-C 
1         
 50 1040 690 0.663 13.80 25.8 49.065
Mitomycin-C 
10         
 5 105 264 2.514 52.80 25.8 464.905
Trend: 1.418        
Probability: 0.078        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 08/02/1982    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 1043 419 0.402 8.38 26.3 0.000
Test Chemical Chlorothalonil 
 0.25      
 50 1031 428 0.415 8.56 26.3 3.337 
 0.75      
 50 1038 436 0.420 8.72 26.3 4.559 
2.5       
 50 1037 522 0.503 10.44 26.3 25.303 
7.5       
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
1.5       
 25 522 732 1.402 29.28 26.3 249.069
Trend: 3.418        
Probability: 0.000        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 09/14/1982    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 1050 439 0.418 8.78 25.8 0.000
Test Chemical Chlorothalonil 
1.5       
 50 1045 470 0.450 9.40 25.8 7.574 
2         
 50 1043 553 0.530 11.06 33.3 26.814 
2.5       
 50 1050 585 0.557 11.70 33.3 33.257 
3         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.3       
 50 1047 710 0.678 14.20 25.8 62.195
Cyclophosphamide 
2         
 5 105 236 2.248 47.20 25.8 437.585
Trend: 5.199        
Probability: 0.000