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Study Information
Study Attribute Value
CEBS Accession Number: 002-02915-0008-0000-7
Chemical Name: Tolbutamide
CASRN: 64-77-7
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 465250
Study Result: Negative


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: Inconclusive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 97 99 93 32 30
    88 100 71 27
    98 97 91 31
    95 104 87 31
Test Chemical Tolbutamide 
100         
 57 76 73 43 44
    59 74 81 46
  
200         
 80 73 101 42 42
    63 70 79 42
  
400         
 53 57 89 56 46
    68 63 73 36
  
800         
 60 53 90 50 44
    56 48 63 37
  
1600         
 75 41 57 25 27
    74 38 64 29
Positive Control Methyl Methane Sulfonate 
15         
 43 29 184 144 180*
    29 18 191 216

Nonactivation Trial: 2 Experiment Call: Negative and Non-Toxic
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 72 82 92 43 34
    84 110 92 37
    75 94 60 27
    73 115 67 31
Test Chemical Tolbutamide 
1000         
 76 93 94 41 40
    71 90 82 38
  
1200         
 62 66 90 49 49
    60 82 88 49
  
1400         
 69 71 77 37 35
    75 73 74 33
  
1600         
 76 62 80 35 34
    83 74 84 34
  
1800         
 79 70 75 32 32
    73 66 70 32
Positive Control Methyl Methane Sulfonate 
15         
 32 28 225 238 182*
    42 33 159 125

Induced S9 Trial: 1 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 60 110 158 87 66
    64 107 115 60
    56 83 84 50
    39r 62 79 68
Test Chemical Tolbutamide 
200         
 92 119 131 48 52
    43 99 71 56
  
400         
 59 85 97 55 51
    65 114 93 48
  
800         
 48 60 60 42 52
    55 90 103 62
  
1000         
 60 74 90 50 48
    68 100 94 46
  
1400         
 48 66 85 59 64
    72 133 151 70
  
1800         
   
Positive Control 3-Methylcholanthrene 
2.5       
 40 25 488 407 454*
    33 24 502 502

Induced S9 Trial: 2 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 72# 100 85 39 48
    59 102 92 52
    71 95 102 48
    68 104 111 55
Test Chemical Tolbutamide 
700         
 41 45 101 81 77*
    51# 55 113 73
  
900         
 57 37 219 128 125*
    55 36 201 123
  
1100         
 63 23 277 146 159*
    47 16 242 172
  
1300         
  
1500         
   
Positive Control 3-Methylcholanthrene 
2.5       
 27 11 437 533 482*
    39 14 498 431

Induced S9 Trial: 3 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 89 112 153 57 59
    74 107 105 47
    79 86 170 72
    89 95 159 60
Test Chemical Tolbutamide 
700         
 93# 86 126 45 61
    80 77 185 77
  
900         
 76 70 179 79 71
    75 85 142 63
  
1100         
 102 64 154 50 60
    98 68 201 69
  
1300         
 95 60 168 59 61
    103 79 194 63
  
1500         
 85 32 125 49 63
    65 20 152 78
  
1700         
   
Positive Control 3-Methylcholanthrene 
2.5       
 48 24 337 235 244*
    57 19 431 253

Induced S9 Trial: 4 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 66 112 70 36 41
    74 108 93 42
    57 84 94 55
    60# 95 55 31
Test Chemical Tolbutamide 
1100         
 73 59 88 40 47
    70 58 114 54
  
1200         
 63 55 96 51 43
    95 90 100 35
  
1300         
 75 74 81 36 29
    89 59 61 23
  
1400         
 77 58 84 36 35
    78 56 81 35
  
1500         
 69 26 73 35 41
    89 32 123 46
  
1600         
   
Positive Control 3-Methylcholanthrene 
2.5       
 41 21 421 342 283*
    41 27 273 225

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