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Study Information
Study Attribute Value
CEBS Accession Number: 002-02469-0002-0000-5
Chemical Name: Methylphenidate hydrochloride
CASRN: 298-59-9
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 597775_CA
Study Result: Positive

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

Trial #:1   Activation: No Activation    Date: 03/08/1983    Harvest Time: 12 hour(s)   Trial Call: 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: Medium 
0         
 100 0 0.000 0.0 0 0.000 0.0 0 0.000 0.0 0 0.000 0.0
Negative (Not Specified) 
0         
 100 3 0.030 3.0 0 0.000 0.0 3 0.030 3.0 0 0.000 0.0
Test Chemical: Methylphenidate hydrochloride 
1500         
 100 1 0.010 1.0 0 0.000 0.0 1 0.010 1.0 0 0.000 0.0 
1750         
 100 16 0.160 16.0 1 0.010 1.0 15 0.150 15.0 0 0.000 0.0 
2000         
 100 16 0.160 15.0 5 0.050 4.0 11 0.110 11.0 0 0.000 0.0
Positive Control: Mitomycin-C 
 0.5       
 100 51 0.510 38.0 17 0.170 15.0 33 0.330 25.0 1 0.010 1.0
Trend: 5.002 2.590 4.262  
Probability: 0.000 0.005 0.000  


Trial #:1_S9   Activation: Induced Rat Liver S9    Date: 03/08/1983    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         
 100 1 0.010 1.0 1 0.010 1.0 0 0.000 0.0 0 0.000 0.0
Medium 
0         
 100 4 0.040 4.0 2 0.020 2.0 2 0.020 2.0 0 0.000 0.0
Test Chemical: Methylphenidate hydrochloride 
1000         
 100 5 0.050 5.0 1 0.010 1.0 4 0.040 4.0 0 0.000 0.0 
1250         
 100 8 0.080 8.0 5 0.050 5.0 3 0.030 3.0 0 0.000 0.0 
1500         
 100 27 0.270 20.0 6 0.060 6.0 21 0.210 17.0 0 0.000 0.0 
1750         
 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         
 100 57 0.570 41.0 32 0.320 25.0 21 0.210 19.0 4 0.040 4.0
Trend: 3.903 1.980 3.913  
Probability: 0.000 0.024 0.000  


Trial #:2   Activation: No Activation    Date: 02/24/1983    Harvest Time: 12.5 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 2 0.020 2.0 0 0.000 0.0 2 0.020 2.0 0 0.000 0.0
Medium 
0         
 100 3 0.030 3.0 0 0.000 0.0 3 0.030 3.0 0 0.000 0.0
Test Chemical: Methylphenidate hydrochloride 
16         
 100 1 0.010 1.0 0 0.000 0.0 1 0.010 1.0 0 0.000 0.0 
50         
 100 4 0.040 4.0 3 0.030 3.0 1 0.010 1.0 0 0.000 0.0 
160         
 100 1 0.010 1.0 0 0.000 0.0 1 0.010 1.0 0 0.000 0.0 
500         
 100 2 0.020 2.0 0 0.000 0.0 2 0.020 2.0 0 0.000 0.0 
1600         
 100 6 0.060 6.0 2 0.020 2.0 3 0.030 3.0 1 0.010 1.0 
5000         
 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 
 0.5       
 100 103 1.030 64.0 53 0.530 45.0 50 0.500 37.0 0 0.000 0.0
Trend: 1.081 0.917 0.269  
Probability: 0.140 0.180 0.394  


Trial #:2_S9   Activation: Induced Rat Liver S9    Date: 02/24/1983    Harvest Time: 12.5 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: Medium 
0         
 100 1 0.010 1.0 0 0.000 0.0 1 0.010 1.0 0 0.000 0.0
Negative (Not Specified) 
0         
 100 3 0.030 3.0 2 0.020 2.0 1 0.010 1.0 0 0.000 0.0
Test Chemical: Methylphenidate hydrochloride 
16         
 100 3 0.030 3.0 0 0.000 0.0 3 0.030 3.0 0 0.000 0.0 
50         
 100 0 0.000 0.0 0 0.000 0.0 0 0.000 0.0 0 0.000 0.0 
160         
 100 2 0.020 2.0 1 0.010 1.0 1 0.010 1.0 0 0.000 0.0 
500         
 100 2 0.020 2.0 1 0.010 1.0 1 0.010 1.0 0 0.000 0.0 
1600         
 100 2 0.020 2.0 0 0.000 0.0 2 0.020 2.0 0 0.000 0.0 
5000         
 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         
 100 123 1.230 65.0 79 0.790 47.0 39 0.390 34.0 5 0.050 5.0
Trend: 0.376 0.828 0.003  
Probability: 0.353 0.204 0.499