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Study Information
Study Attribute Value
CEBS Accession Number: 002-01933-0006-0000-4
Chemical Name: Cytarabine hydrochloride
CASRN: 69-74-9
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 105521
Study Result: Positive


Table Instructions and Notes:
Studies are indicated to be "Nontoxic" when the observed reductions in relative total growth did not indicate that the maximum tolerated dose was achieved.

Nonactivation Trial: 1 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Fischer Medium 
 0         
 88 84 68 26 31
    90 104 79 29
    80 108 89 37
    70 103 68 32
Test Chemical Cytarabine hydrochloride 
5         
 61 10 908 500 493*
    49 10 708 487
  
10         
 53 10 777 487 529*
    49 9 846 572
  
20         
 42 7 601 473 438*
    55 9 669 403
  
40         
 16 2 403 857 766*
    21 3 425 675
  
80         
 11 1 321 944
    7r 1 258 1259
Positive Control Methyl Methane Sulfonate 
15         
 35 27 188 181 186*
    33 23 187 191

Nonactivation Trial: 2 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Fischer Medium 
 0         
 66 92 66 34 32
    69 113 84 41
    67 106 57 28
    64 90 50 26
Test Chemical Cytarabine hydrochloride 
5         
 38 9 948 828 796*
    42 9 951 764
  
10         
 38 5 795 691 799*
    38 6 1042 906
  
20         
 27 3 441 538 547*
    27 4 450 556
  
40         
 10 1 190 633 626*
    20 2 377 618
  
60         
 14 1 926 2286 2412*
    11 1 812 2537
  
80         
   
Positive Control Methyl Methane Sulfonate 
15         
 32 27 88 91 120*
    35 22 156 149

Nonactivation Trial: 3 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Fischer Medium 
 0         
 52 85 56 36 36
    54 100 55 34
    53 108 47 30
    52 108 72 46
Test Chemical Cytarabine hydrochloride 
 0.16      
 50 103 52 35 41
    47 105 66 47
  
 0.31      
 67 101 66 33 40
    59 80 85 48
  
 0.63      
 56 75 90 54 53
    61 85 94 52
  
1.25      
 53 65 196 124 130*
    57 62 231 136
  
2.5       
 38 20 468 412 410*
    44 21 532 408
  
5         
 39 9 841 728 718*
    40 9 838 707
Positive Control Methyl Methane Sulfonate 
15         
 12 12 113 323 304*
    13 14 108 284

Nonactivation Trial: 4 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Fischer Medium 
 0         
 84 92 133 53 48
    86 108 120 47
    88 93 132 50
    94 106 117 42
Test Chemical Cytarabine hydrochloride 
 0.31      
 80 85 138 58 60
    101 86 189 63
  
 0.63      
 108 76 224 69 67
    102 66 198 65
  
1.25      
 86 59 453 176 186*
    91 55 536 197
  
2.5       
 54 17 769 473 423*
    61 18 677 373
  
5         
 39 2 1125 966 1003*
    41 3 1269 1040
Positive Control Methyl Methane Sulfonate 
15         
 29 18 384 439 444*
    33 24 437 448

Nonactivation Trial: 5 Experiment Call:
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Fischer Medium 
 0         
 106 109 42 13 20
    77 106 64 28
    83 103 35 14
    71 82 55 26
Test Chemical Cytarabine hydrochloride 
 0.125     
 56 84 49 29 26
    87 85 58 22
  
 0.25      
 83 63 66 27 40*
    82 63 133 54
  
 0.5       
 57 47 263 155 143*
    69 45 272 131
  
1         
 52 17 467 301 335*
    48 13 528 369
  
2         
 43 6 751 589 590*
    45# 6 798 591
  
4         
 30 2 440 492 480*
    32# 2 442 468
Positive Control Methyl Methane Sulfonate 
15         
 22 19 147 223 196*
    40 26 200 169

Nonactivation Trial: 6 Experiment Call:
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Fischer Medium 
 0         
 55 98 48 29 23
    66 106 43 22
    63 97 44 23
    55# 98 30 18
Test Chemical Cytarabine hydrochloride 
 0.0125    
 88# 128 41 16 17
    92# 131 52 19
  
 0.025     
 78 118 56 24 19
    92 150 40 14
  
 0.05      
 69 115 50 24 19
    67# 110 28 14
  
 0.1       
 91 103 49 18 17
    107# 117 54 17
  
 0.2       
 77 113 52 22 24
    75 103 58 26
  
 0.4       
 100 93 122 41 42*
    94 92 121 43
Positive Control Methyl Methane Sulfonate 
15         
 36 26 136 125 137*
    30 24 136 149

Footnotes:
Asterisks(*) indicate significant responses.
r = rejected value due to quality control criteria
# = reduced sample size because of the loss of one culture dish due to contamination