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Study Information
Study Attribute Value
CEBS Accession Number: 002-01756-0009-0000-0
Chemical Name: Butylated hydroxytoluene
CASRN: 128-37-0
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 441614
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: Inconclusive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 66 113 72 36 38
    64# 113 67.5 35
    55 90 62 38
    57 84 72 42
Test Chemical Butylated hydroxytoluene 
1.25      
 78 109 51 22 28
    78 122 81 35
  
2.5       
 63 95 76 40 46
    62 92 95 51
  
5         
 75# 86 71 32 31
    75# 109 69 31
  
10         
 76 105 103 45 48
    73 105 110 50
  
20         
 69# 81 139 67 58
    71 87 105 49
  
40         
   
Positive Control Methyl Methane Sulfonate 
15         
 19 16 138 249 213*
    17# 16 91.5 178

Nonactivation Trial: 2 Experiment Call:
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 113 148 110 32 35
    104 60 110 35
    93 96 89 32
    95 95 110 39
Test Chemical Butylated hydroxytoluene 
6         
 99 92 128 43 39
    91 102 96 35
  
12         
 112 98 130 39 39
    102 105 120 39
  
18         
 101 25 155 51 79*
    86 27 274 107
  
24         
   
Positive Control Methyl Methane Sulfonate 
15         
 50 27 321 213 172*
    57 26 223 132

Nonactivation Trial: 3 Experiment Call: Inconclusive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 96 105 142 50 58
    66 95 124 63
    99 109 146 49
    89 91 183 69
Test Chemical Butylated hydroxytoluene 
14         
 88 77 164 62 54
    119 93 164 46
  
18         
 97 84 186 64 58
    117 94 185 53
  
22         
 99 86 196 66 68
    75 69 156 69
  
26         
 71 77 168 79 73
    73 78 147 67
  
30         
 79 72 165 70 70
    76 56 160 70
Positive Control Methyl Methane Sulfonate 
15         
 55 28 336 205 193*
    49 29 265 182

Nonactivation 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         
 85 90 151 59 68
    73# 109 161 74
    83 98 172 69
    76 103 160 71
Test Chemical Butylated hydroxytoluene 
5         
 73 119 152 69 72
    67 102 149 75
  
10         
 94 105 148 52 56
    89 103 158 60
  
15         
 83 91 153 61 61
    79 101 142 60
  
20         
 81 69 180 74 76
    82 89 193 78
  
25         
   
Positive Control Methyl Methane Sulfonate 
15         
 58 37 308 178 178*
    39 28 207 178

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         
 110 103 170 52 63
    84 101 147 58
    71 100 164 77
    80 96 156 65
Test Chemical Butylated hydroxytoluene 
8         
 110 78 192 58 62
    110 76 216 65
  
12         
 90 55 220 81 76
    95 72 200 70
  
16         
 98 45 262 89 88
    77 48 198 86
  
20         
 88 27 301 114 109*
    104 30 322 104
  
24         
 58 12 307 176 178*
    65 10 351 180
  
28         
   
Positive Control 3-Methylcholanthrene 
2.5       
 77 70 515 223 230*
    74 70 522 236

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         
 88 95 177 67 62
    96 86 176 61
    84 128 124 49
    78 90 162 69
Test Chemical Butylated hydroxytoluene 
2         
 61 82 121 66 59
    80 58 125 52
  
8         
 59 57 138 78 78
    68 55 159 78
  
14         
 71 12 327 153 170*
    43 8 238 187
  
20         
   
Positive Control 3-Methylcholanthrene 
2.5       
 53 20 821 513 532*
    51 27 839 550

Induced S9 Trial: 3 Experiment Call:
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 97 97 151 52 49
    79 91 138 58
    104 112 118 38
    90 100 129 48
Test Chemical Butylated hydroxytoluene 
2         
 67 74 158 78 70
    69 74 128 62
  
6         
 67 61 172 86 85*
    72 48 183 85
  
10         
 45 6 278 204 194*
    59 11 327 184
  
14         
   
Positive Control 3-Methylcholanthrene 
2.5       
 43 21 639 499 485*
    47 25 658 470

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