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Study Information
Study Attribute Value
CEBS Accession Number: 002-02419-0001-0000-9
Chemical Name: Methoxychlor
CASRN: 72-43-5
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 344617_SCE
Study Result: Positive

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

Trial #: 1    Activation: No Activation    Date: 07/10/1990    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 Methoxychlor 
0         
 50 1044 338 0.324 6.76 26.0 -16.323
Dimethyl Sulfoxide 
0         
 50 1039 402 0.387 8.04 26.0 0.000
Test Chemical Methoxychlor 
 0.5       
 50 1048 418 0.399 8.36 26.0 3.087 
1.7       
 50 1052 423 0.402 8.46 26.0 3.924 
5         
 50 1046 425 0.406 8.50 26.0 5.014 
17         
 0 0 0 0.000 0.00 31.0 N/A
Positive Control Mitomycin-C 
 0.001     
 50 1052 571 0.543 11.42 26.0 40.285
Mitomycin-C 
 0.004     
 10 207 227 1.097 22.70 26.0 183.429
Trend: 0.704        
Probability: 0.241        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 07/10/1990    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 1046 389 0.372 7.78 26.0 0.000
Dimethyl Sulfoxide 
0         
 50 1047 389 0.372 7.78 31.0 -0.096
Test Chemical Methoxychlor 
17         
 50 1049 426 0.406 8.52 26.0 9.198 
50         
 50 1048 507 0.484 10.14 26.0 30.085 
167         
 50 1051 536 0.510 10.72 31.0 37.134 
500         
 0 0 0 0.000 0.00 31.0 N/A 
1667         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.125     
 50 1049 504 0.480 10.08 26.0 29.192
Cyclophosphamide 
 0.5       
 10 209 308 1.474 30.80 26.0 296.266
Trend: 5.330        
Probability: 0.000        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 11/08/1990    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 1051 401 0.382 8.02 26.0 0.000
Dimethyl Sulfoxide 
0         
 50 1050 401 0.382 8.02 31.0 0.095
Test Chemical Methoxychlor 
75         
 50 1046 420 0.402 8.40 26.0 5.239 
150         
 50 1046 528 0.505 10.56 26.0 32.300 
300         
 50 1046 527 0.504 10.54 31.0 32.050
Positive Control Cyclophosphamide 
 0.125     
 50 1050 569 0.542 11.38 26.0 42.030
Cyclophosphamide 
 0.5       
 10 209 262 1.254 26.20 26.0 228.559
Trend: 5.085        
Probability: 0.000