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Study Information
Study Attribute Value
CEBS Accession Number: 002-02502-0008-0000-9
Chemical Name: N,N'-Dicyclohexylthiourea
CASRN: 1212-29-9
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 028630
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: 2 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 64 100 174 91 90
    69 103 218 106
    72# 97 162 75
Test Chemical N,N'-Dicyclohexylthiourea 
9.375     
 71 94 173 81 107
    45# 64 178.5 134
  
18.75      
 52 22 190 121 116
    63# 21 210 111
  
37.5       
 40 12 189 158 138
    47# 18 165 117
  
75         
 37 7 337 306 259*
    42 6 268 211
  
150         
   
Positive Control Ethyl Methane Sulfonate 
250         
 58 63 506 293 350*
    39 48 481 408

Nonactivation Trial: 3 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 91 105 131 48 53
    72 99 125 58
    91 97 132 49
    101 99 172 57
Test Chemical N,N'-Dicyclohexylthiourea 
18.75      
 86 62 90 35 48
    79 62 143 60
  
37.5       
 95 25 236 83 87*
    80 22 216 91
  
75         
 87 27 157 61 68
    75 25 169 75
  
150         
 57 6 497 290 268*
    60 10 443 246
Positive Control Ethyl Methane Sulfonate 
250         
 70 73 632 302 376*
    49 44 660 449

Non-Induced S9 Trial: 1 Experiment Call: Rejected
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 84 106 174 69 71
    94 92 197 70
    76 112 146 64
    76 89 183 81
Test Chemical N,N'-Dicyclohexylthiourea 
18.75      
 84 84 212 84 80
    101 87 228 75
  
37.5       
 76 46 184 80 75
    89 44 185 69
  
75         
 85 35 225 88 80
    93 45 201 72
  
150         
 73 29 219 100 85
    97 32 204 70
  
300         
 78 25 205 88 89
    70 33 189 90
Positive Control 3-Methylcholanthrene 
2.5       
 82 79 273 111 117*
    99 81 367 124

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         
 78 95 96 41 50
    80 111 130 54
    81# 93 130.5 54
Test Chemical N,N'-Dicyclohexylthiourea 
9.375     
 106 105 141 44
  
18.75      
 91 84 116 42 44
    85 72 115 45
  
37.5       
 118# 44 138 39
  
75         
 86# 24 84 33 35
    88# 26 99 37
  
150         
 82 11 111 45 37
    117# 14 102 29
Positive Control 3-Methylcholanthrene 
2.5       
 44# 24 388.5 293 310*
    39 18 385 326

Induced S9 Trial: 2 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Methanol 
 0         
 84 97 175 70 73
    84 119 139 55
    74 95 181 81
    59 88 152 85
Test Chemical N,N'-Dicyclohexylthiourea 
18.75      
 63 74 156 82 88
    59 73 165 93
  
37.5       
 84 43 204 81 102
    63 32 230 122
  
75         
 62 26 293 157 153*
    49 21 220 150
  
150         
 68 20 322 159 158*
    58 21 271 157
  
300         
 71 25 321 151 152*
    64 20 293 153
Positive Control 3-Methylcholanthrene 
2.5       
 29 13 707 813 866*
    27 9 754 920

Induced S9 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         
 29r 28 213 246 81
    33r 44 169 172
    76 113 182 80
    77 87 190 82
Test Chemical N,N'-Dicyclohexylthiourea 
18.75      
 66 57 184 93 84
    87 54 196 75
  
37.5       
 74 45 167 75 82
    85 35 228 89
  
75         
 75 23 216 97 106
    58 26 201 116
  
150         
 61 32 158 87 85
    83 35 209 84
  
300         
 88 22 191 73 80
    59 30 153 87
Positive Control 3-Methylcholanthrene 
2.5       
 42 29 624 501 535*
    34 22 584 570

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