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Study Information
Study Attribute Value
CEBS Accession Number: 002-02631-0002-0000-6
Chemical Name: Parathion
CASRN: 56-38-2
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 580599_CA
Study Result: Negative

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

Trial #:1   Activation: No Activation    Date: 01/11/1983    Harvest Time: 20.8 hour(s)   Trial Call: Negative   
  Dose
µg/mL		 Total
Cells Examined		 Total Aberrations Complex Aberrations Simple Aberrations Other Abs
No. of
Abs		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs
Vehicle Control: Negative (Not Specified) 
0         
 100 2 0.020 2.0 1 0.010 1.0 0 0.000 0.0 1 0.010 1.0
Dimethyl Sulfoxide 
0         
 100 4 0.040 4.0 2 0.020 2.0 0 0.000 0.0 2 0.020 2.0
Test Chemical: Parathion 
22.7       
 100 2 0.020 2.0 1 0.010 1.0 1 0.010 1.0 0 0.000 0.0 
45.4       
 100 4 0.040 4.0 1 0.010 1.0 0 0.000 0.0 3 0.030 3.0 
60.5       
 100 0 0.000 0.0 0 0.000 0.0 0 0.000 0.0 0 0.000 0.0 
70.8       
 0 0 0.000 0.0 0 0.000 0.0 0 0.000 0.0 0 0.000 0.0
Positive Control: Mitomycin-C 
 0.0625    
 50 35 0.700 50.0 27 0.540 42.0 8 0.160 16.0 0 0.000 0.0
Trend: -1.174 -1.265 -0.600  
Probability: 0.880 0.897 0.726  


Trial #:1_S9   Activation: Induced Rat Liver S9    Date: 02/03/1983    Harvest Time: 10.5 hour(s)   Trial Call: Negative   
  Dose
µg/mL		 Total
Cells Examined		 Total Aberrations Complex Aberrations Simple Aberrations Other Abs
No. of
Abs		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs
Vehicle Control: Negative (Not Specified) 
0         
 100 1 0.010 1.0 0 0.000 0.0 1 0.010 1.0 0 0.000 0.0
Dimethyl Sulfoxide 
0         
 100 1 0.010 1.0 1 0.010 1.0 0 0.000 0.0 0 0.000 0.0
Test Chemical: Parathion 
98         
 100 1 0.010 1.0 0 0.000 0.0 0 0.000 0.0 1 0.010 1.0 
115         
 100 3 0.030 3.0 3 0.030 3.0 0 0.000 0.0 0 0.000 0.0 
135         
 100 1 0.010 1.0 0 0.000 0.0 1 0.010 1.0 0 0.000 0.0 
161         
 0 0 0.000 0.0 0 0.000 0.0 0 0.000 0.0 0 0.000 0.0
Positive Control: Cyclophosphamide 
50         
 50 13 0.260 18.0 7 0.140 12.0 5 0.100 8.0 1 0.020 2.0
Trend: 0.370 -0.001 1.338  
Probability: 0.356 0.500 0.090  


Trial #:2_S9   Activation: Induced Rat Liver S9    Date: 01/11/1983    Harvest Time: 20.8 hour(s)   Trial Call: Negative   
  Dose
µg/mL		 Total
Cells Examined		 Total Aberrations Complex Aberrations Simple Aberrations Other Abs
No. of
Abs		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs		 No. of
Abs.		 Abs
Per
Cell		 % Cells
With
Abs
Vehicle Control: Negative (Not Specified) 
0         
 100 0 0.000 0.0 0 0.000 0.0 0 0.000 0.0 0 0.000 0.0
Dimethyl Sulfoxide 
0         
 100 2 0.020 2.0 1 0.010 1.0 0 0.000 0.0 1 0.010 1.0
Test Chemical: Parathion 
60.5       
 100 2 0.020 2.0 2 0.020 2.0 0 0.000 0.0 0 0.000 0.0 
70.8       
 100 1 0.010 1.0 0 0.000 0.0 1 0.010 1.0 0 0.000 0.0 
90.8       
 100 4 0.040 4.0 2 0.020 2.0 0 0.000 0.0 2 0.020 2.0 
121         
 0 0 0.000 0.0 0 0.000 0.0 0 0.000 0.0 0 0.000 0.0
Positive Control: Cyclophosphamide 
10         
 50 15 0.300 24.0 7 0.140 14.0 7 0.140 12.0 1 0.020 2.0
Trend: 0.831 0.321 0.320  
Probability: 0.203 0.374 0.374