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Study Information
Study Attribute Value
CEBS Accession Number: 002-01690-0018-0000-7
Chemical Name: Benzene
CASRN: 71-43-2
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 342509
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
  Conc.
uL/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Ethanol 
 0         
 89 107 91 34 37
    91 94 120 44
    80 101 83 35
    74 98 77 35
Test Chemical Benzene 
 0.0625    
 70 74 81 38 39
    60 73 66 37
    51 62 63 42
  
 0.125     
 80 66 64 27 34
    73# 66 75 34
    72 67 88 41
  
 0.25      
 72 59 68 31 39
    74 63 88 40
    64 44 90 47
  
 0.5       
 87# 32 113 43
  
1         
 75 14 121 54 48
    74 12 100 45
    78# 16 108 46
  
3         
   
   
Positive Control Ethyl Methane Sulfonate 
250         
 70 50 740 354 376*
    71 45 843 395
    82 45 931 380

Nonactivation Trial: 2 Experiment Call: Negative
  Conc.
uL/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Ethanol 
 0         
 100 98 151 50 45
    91# 94 144 53
    113# 108 106 31
Test Chemical Benzene 
 0.0313    
 91 94 88 32 35
    110# 97 126 38
  
 0.0625    
 95 110 69 24 28
    101 110 101 33
    106 105 88 28
  
 0.125     
 107 110 111 35 31
    94 103 81 29
    103 106 91 29
  
 0.25      
 100 87 107 36 34
    103 108 91 29
    92 98 102 37
  
 0.5       
 116# 78 68 20 29
    112 88 105 31
    77 66 80 35
  
1         
 48
    80# 25 141 59
    84 27 96 38
  
3         
   
   
Positive Control Ethyl Methane Sulfonate 
250         
 80# 53 859 360 392*
    83 52 912 366
    58 50 789 451

Non-Induced S9 Trial: 1 Experiment Call: Rejected
  Conc.
uL/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Ethanol 
 0         
 70 143 251 120 120
    78 99 333 143
    80 87 262 109
    60 70 198 111
Test Chemical Benzene 
 0.25      
 65 86 184 95 110
    56 81 212 127
    74# 73 236 107
  
 0.5       
 70 42 291 138 156
    54 57 275 170
    54 64 260 161
  
 0.75      
 46 8 305 221 217*
    47 42 254 181
    37 14 273 248
  
1         
 191*
    49 18 321 217
    67 43 332 166
  
1.5       
   
   
Positive Control 3-Methylcholanthrene 
3.5       
 62 40 710 381 383*
    58 42 689 393
    64 50 726 376

Non-Induced S9 Trial: 2 Experiment Call: Rejected
  Conc.
uL/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Ethanol 
 0         
 71 136 114 54 60
    65 101 141 72
    54 60 142 87
    62 103 51 28
Test Chemical Benzene 
 0.25      
 57 39 170 100 102*
    51 33 181 118
    67 55 179 89
  
 0.5       
 47 17 158 113 113*
    43 22 144 112
    37 19 127 114
  
 0.75      
 28 21 96 114 88
    54# 41 114 70
    67 59 164 81
  
1         
   
    60 41 137 76
  
1.5       
   
   
Positive Control 3-Methylcholanthrene 
3.5       
 63 73 237 126 246*
    50 40 289 194
    62 44 772 417

Non-Induced S9 Trial: 3 Experiment Call: Negative
  Conc.
uL/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Ethanol 
 0         
 77 99 91 39 54
    79# 96 179 76
    81 101 109 45
    80 104 133 55
Test Chemical Benzene 
 0.125     
 77 57 132 57 50
    69 68 107 52
    88 78 111 42
  
 0.25      
 60 61 89 49 51
    58# 67 86 49
    55 58 92 55
  
 0.5       
 58 65 78 45 54
    60 61 140 77
    62# 62 72 39
  
 0.75      
 64 45 135 71 56
    68# 24 135 67
    65 53 61 31
  
1         
 72 45 113 53 51
    49# 19 74 50
  
1.5       
 93 29 130 46
   
   
  
2         
   
   
Positive Control 3-Methylcholanthrene 
3.5       
 99 71 608 204 194*
    87# 63 538 207
    102# 69 523 171

Non-Induced S9 Trial: 4 Experiment Call: Negative
  Conc.
uL/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Ethanol 
 0         
 67 113 58 29 38
    65 105 84 43
    68 97 74 37
    71 86 88 41
Test Chemical Benzene 
 0.125     
 72 68 113 52 43
    63 64 57 30
    63# 71 86 46
  
 0.25      
 67 69 68 34 40
    61 61 80 44
    76 87 94 42
  
 0.5       
 65 54 105 54 49
    63 67 100 53
    75 62 90 40
  
 0.75      
 72 47 134 62 51
    58 71 88 50
    63 16 76 40
  
1         
 71 72 71 33 40
    66 46 84 43
    78 22 100 43
  
1.5       
 64 6 111 58
   
   
  
2         
   
   
Positive Control 3-Methylcholanthrene 
3.5       
 87 93 332 128 132*
    94# 88 378 135
    87 78 349 133

Induced S9 Trial: 1 Experiment Call: Inconclusive
  Conc.
uL/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Ethanol 
 0         
 101 125 142 47 55
    82 49 139 56
    90 109 153 57
    80 118 146 61
Test Chemical Benzene 
 0.0625    
 95 106 130 46 54
    77 121 131 57
    72 116 128 59
  
 0.125     
 89 78 183 68 59
    82 115 145 59
    73 83 110 50
  
 0.25      
 66 84 127 64 57
    71 119 115 54
    66 113 106 54
  
 0.5       
 81 73 101 41 51
    85 91 145 57
    102 46 169 55
  
1         
 84
    74 38 179 80
    73 32 193 88
  
2         
   
   
Positive Control 3-Methylcholanthrene 
2.5       
 77 60 501 218 224*
    92 74 639 231

Induced S9 Trial: 2 Experiment Call: Inconclusive
  Conc.
uL/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Ethanol 
 0         
 99 91 141 47 50
    118 109 148 42
    110 93 162 49
    99 106 186 62
Test Chemical Benzene 
 0.0625    
 85 97 124 49 56
    66# 88 149 76
    87# 88 111 42
  
 0.125     
 85 90 96 38 45
    75 83 103 46
    76 93 120 53
  
 0.25      
 85 94 122 48 61
    73 79 160 74
    82 77 152 62
  
 0.5       
 93 56 165 59 53
    101 70 168 56
    116 72 151 43
  
1         
   
   
Positive Control 3-Methylcholanthrene 
2.5       
 95 76 501 176 187*
    81# 69 457 189
    87 72 508 195

Induced S9 Trial: 3 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Ethanol 
 0         
 90 115 204 75 70
    80 94 170 71
    97 99 207 71
    96 92 184 64
Test Chemical Benzene 
62.5       
 80 65 112 47 59
    76 61 119 52
    70 60 166 79
  
125         
 71 56 154 72 64
    91 59 166 61
    90 63 162 60
  
250         
 74# 55 234 106 88
    69 48 196 94
    82 61 156 64
  
500         
 89 45 241 91 95
    72 31 220 101
    62 28 174 94
  
750         
 81 19 213 87 96
    80 19 215 89
    60 9 201 111
  
1000         
   
    72 14 215 100
  
1500         
   
   
Positive Control 3-Methylcholanthrene 
2.5       
 52 25 680 435 470*
    45 20 666 490
    35 8 514 487

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