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Study Information
Study Attribute Value
CEBS Accession Number: 002-02756-0028-0000-2
Chemical Name: Pyridine
CASRN: 110-86-1
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 746434
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: Negative and Non-Toxic
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Fischer Medium 
 0         
 112 102 95 28 30
    101 89 92 31
    108 103 100 31
    99 106 86 29
Test Chemical Pyridine 
312.5       
 124r 115 112 30
    123r 115 98 27
  
625         
 105 102 95 30 34
    89 100 99 37
  
1250         
 86 101 80 31 26
    73 88 47 21
  
2500         
 78 71 56 24 26
    94 69 81 29
  
5000         
 88 77 113 43 34
    82 70 60 24
Positive Control Methyl Methane Sulfonate 
15         
 49 26 195 133 160*
    43 26 239 186

Nonactivation Trial: 2 Experiment Call: Equivocal
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Fischer Medium 
 0         
 65 102 120 62 49
    84 97 122 49
    99 102 136 46
    76 98 89 39
Test Chemical Pyridine 
1000         
 58 90 106 61 63
    82 101 160 65
  
2000         
 68 78 167 81 75
    74 77 154 69
  
3000         
 71 76 161 76 77*
    78 68 182 78
  
4000         
 55 76 154 94 81*
    47 68 97 68
  
5000         
 69 66 151 73 85*
    48 57 138 97
Positive Control Methyl Methane Sulfonate 
15         
 24 20 473 671 610*
    27 23 440 550

Nonactivation Trial: 3 Experiment Call:
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Fischer Medium 
 0         
 102 106 85 28 25
    71 84 70 33
    108 110 67 21
    98 100 60 20
Test Chemical Pyridine 
2000         
 79 85 53 22 24
    90 87 68 25
  
3000         
 90 79 64 24 25
    116 85 89 26
  
4000         
 88 79 145 55 47*
    72 75 86 40
  
5000         
 89 67 79 30 30
    82 70 73 30
Positive Control Methyl Methane Sulfonate 
15         
 23 13 103 151 159*
    25 14 126 166

Induced S9 Trial: 1 Experiment Call: Negative and Non-Toxic
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Fischer Medium 
 0         
 74 105 141 64 55
    83 102 137 55
    79 104 124 53
    90 90 126 47
Test Chemical Pyridine 
1000         
 89 96 152 57 56
    82 88 133 54
  
2000         
 77 99 123 53 68
    94 77 230 82
  
3000         
 89 80 140 52 71
    77 86 204 89
  
4000         
 78 79 147 63 59
    100 70 167 55
  
5000         
 98 73 207 70 63
    95 81 158 55
Positive Control 3-Methylcholanthrene 
2.5       
 43 20 726 561 556*
    50 18 820 552

Induced S9 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 Fischer Medium 
 0         
 105 98 159 50 52
    100 93 188 62
    91 108 138 50
    85 101 111 43
Test Chemical Pyridine 
2000         
 87 108 119 46 41
    86 104 95 37
  
3000         
 79 105 117 49 43
    78 101 87 37
  
4000         
 84 91 107 42 41
    80 97 94 39
  
5000         
 109 84 115 35 33
    109 78 101 31
Positive Control 3-Methylcholanthrene 
2.5       
 58 28 791 451 436*
    54 24 686 421

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