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Study Information
Study Attribute Value
CEBS Accession Number: 002-02251-0001-0000-3
Chemical Name: Hexamethyldisilazane
CASRN: 999-97-3
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: A81034_CA
Study Result: Negative

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

Trial #:1   Activation: No Activation    Date: 05/05/1992    Harvest Time: 12 hour(s)   Trial Call: Weakly Positive*   
  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         
 200 2 0.010 1.0 1 0.005 0.5 1 0.005 0.5 0 0.000 0.0
Acetone 
0         
 200 3 0.015 1.5 2 0.010 1.0 1 0.005 0.5 0 0.000 0.0
Test Chemical: Hexamethyldisilazane 
503         
 200 3 0.015 1.5 2 0.010 1.0 1 0.005 0.5 0 0.000 0.0 
1081         
 200 2 0.010 1.0 2 0.010 1.0 0 0.000 0.0 0 0.000 0.0 
2325         
 200 2 0.010 1.0 0 0.000 0.0 2 0.010 1.0 0 0.000 0.0 
5000         
 50 38 0.760 40.0 0 0.000 0.0 38 0.760 40.0 0 0.000 0.0
Positive Control: Mitomycin-C 
 0.4       
 25 22 0.880 48.0 12 0.480 40.0 10 0.400 20.0 0 0.000 0.0
Trend: 6.568 -1.289 7.968  
Probability: 0.000 0.901 0.000  


Trial #:1_S9   Activation: Induced Rat Liver S9    Date: 05/05/1992    Harvest Time: 12 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         
 200 4 0.020 1.5 2 0.010 1.0 2 0.010 1.0 0 0.000 0.0
Acetone 
0         
 200 3 0.015 1.5 2 0.010 1.0 1 0.005 0.5 0 0.000 0.0
Test Chemical: Hexamethyldisilazane 
1081         
 200 3 0.015 1.0 3 0.015 1.0 0 0.000 0.0 0 0.000 0.0 
2325         
 200 5 0.025 1.5 1 0.005 0.5 4 0.020 1.0 0 0.000 0.0 
5000         
 200 2 0.010 1.0 2 0.010 1.0 0 0.000 0.0 0 0.000 0.0
Positive Control: Cyclophosphamide 
20         
 25 26 1.040 44.0 7 0.280 24.0 9 0.360 24.0 10 0.400 4.0
Trend: -0.285 -0.170 -0.259  
Probability: 0.612 0.567 0.602  


Trial #:2   Activation: No Activation    Date: 01/20/1993    Harvest Time: 12 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: Acetone 
0         
 200 3 0.015 1.5 2 0.010 1.0 1 0.005 0.5 0 0.000 0.0
Negative (Not Specified) 
0         
 200 1 0.005 0.5 0 0.000 0.0 1 0.005 0.5 0 0.000 0.0
Test Chemical: Hexamethyldisilazane 
3000         
 200 5 0.025 2.0 2 0.010 1.0 3 0.015 1.5 0 0.000 0.0 
4000         
 200 1 0.005 0.5 0 0.000 0.0 1 0.005 0.5 0 0.000 0.0 
5000         
 200 12 0.060 2.0 0 0.000 0.0 12 0.060 2.0 0 0.000 0.0
Positive Control: Mitomycin-C 
 0.4       
 25 10 0.400 40.0 3 0.120 12.0 7 0.280 28.0 0 0.000 0.0
Trend: -0.065 -1.825 0.988  
Probability: 0.526 0.966 0.161