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Study Information
Study Attribute Value
CEBS Accession Number: 002-01687-0002-0000-6
Chemical Name: Benz(a)anthracene
CASRN: 56-55-3
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: G62003
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 Dimethyl Sulfoxide 
 0         
 115 111 106 31 33
    88 89 92 35
Test Chemical Benz(a)anthracene 
10.2       
 86 81 77 30 41
    96 89 147 51
  
25.6       
 83 78 124 50 50
    78 76 116 49
  
64         
 83 49 139 56 70*
    69 39 174 84
  
160         
 81 30 133 55 63*
    77 41 163 71
  
400         
 67 25 205 102 101*
    75 30 227 101
  
1000         
 60 18 153 85 92*
    69 15 207 100
Positive Control Ethyl Methane Sulfonate 
500         
 34 26 716 695 681*
    35 29 696 666

Nonactivation Trial: 2 Experiment Call: No Call
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 101 104 123 41 38
    111 96 115 34
Test Chemical Benz(a)anthracene 
4.1       
 113 98 136 40 41
    110 113 137 42
  
10.2       
 131r 130 167 42
    119 119 118 33
  
25.6       
 125r 108 82 22
    118 102 141 40
  
64         
 105 80 139 44
    132r 90 93 23
  
160         
 116 83 132 38 45
    100 71 158 53
  
400         
    102 40 149 49
  
1000         
   
Positive Control Ethyl Methane Sulfonate 
500         
 702*
    52 26 1088 702

Nonactivation Trial: 3 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         
 89 82 81 30 24
    97 116 67 23
    93 104 60 22
    103 99 62 20
Test Chemical Benz(a)anthracene 
108         
 107 78 73 23 31
    90 70 95 35
    94 74 97 35
  
134         
 84 73 100 40 35
    119 91 126 35
    97 75 85 29
  
168         
 105 77 61 19 30
    96 70 96 33
    87 63 96 37
  
210         
 88 64 63 24 34
    71 52 85 40
    90 60 104 39
  
262         
 86 56 86 33 32
    104 67 101 33
    95 67 84 30
  
328         
 80 41 96 40 36*
    84 45 84 33
    89 52 91 34
Positive Control Ethyl Methane Sulfonate 
500         
 49 33 904 617 594*
    53 37 940 595
    54 38 928 571

Nonactivation Trial: 4 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         
 128r 118 189 49 44
    108 112 153 47
    100 102 128 43
    94 86 119 42
Test Chemical Benz(a)anthracene 
81         
 106 81 148 47 40
    110 102 127 39
    115 117 124 36
  
108         
 109 52 113 35 39
    104 61 133 42
    102 103 122 40
  
144         
 117 94 231 66 53
    109 96 158 48
    106 97 147 46
Positive Control Ethyl Methane Sulfonate 
500         
 66 46 1320 663 643*
    60 25 1188 656
    73 22 1332 608

Non-Induced S9 Trial: 1 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 85 103 103 40 43
    89 97 119 45
Test Chemical Benz(a)anthracene 
2.7       
 72 81 110 51 66
    79 96 190 81
  
3.6       
 73 74 128 59 57
    68 88 114 56
  
4.7       
 70 69 210 101 93*
    92 79 232 84
  
6.3       
 77 62 188 82 83*
    92 66 230 84
  
8.4       
 77 50 318 137 129*
    83 41 299 121
  
11.3       
 42 6 288 229 206*
    46 6 252 184
  
15         
   
Positive Control 3-Methylcholanthrene 
6         
 80 56 494 205 203*
    66 49 399 201

Induced S9 Trial: 1 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 111 109 64 19 18
    89 91 47 18
Test Chemical Benz(a)anthracene 
3.9       
 90 87 39 14 21
    89 88 71 27
  
4.9       
 102 77 90 29 28
    98 67 80 27
  
6.1       
 92 72 75 27 30
    99 65 95 32
  
7.7       
 74 51 77 35 28
    82 48 54 22
  
9.6       
 56 18 106 63 63*
    63 17 119 63
  
12         
   
Positive Control 3-Methylcholanthrene 
6         
 59 34 305 172 186*
    61 28 365 199

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         
 93 103 284 102 113
    90 97 337 124
Test Chemical Benz(a)anthracene 
3.9       
 84 85 396 157 158
    83 75 395 159
  
4.9       
 65 54 445 227 216*
    68 50 419 206
  
6.1       
 69 34 436 211 226*
    60 28 432 241
  
7.7       
 62 18 475 257 244*
    61 20 424 232
  
8.5       
 49 13 454 307 320*
    54 12 539 333
  
9.5       
 46 6 504 367 347*
    51 8 502 328
  
10.5       
   
Positive Control 3-Methylcholanthrene 
5         
 43 23 475 373 359*
    51 23 531 346

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