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Study Information
Study Attribute Value
CEBS Accession Number: 002-02502-0010-0000-2
Chemical Name: N,N'-Dicyclohexylthiourea
CASRN: 1212-29-9
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: G55329
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.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 74 95 82 37 33
    81 105 69 28
Test Chemical N,N'-Dicyclohexylthiourea 
27.7       
 90 65 32 12 19
    70 53 53 25
  
50.3       
 72 35 66 30 28
    77 50 58 25
  
91.5       
 72 33 35 16 17
    74 32 41 18
  
166.4       
 64 27 59 31 31
    59 21 55 31
  
302.5       
 63 19 47 25 21
    64 24 31 16
  
550         
 64 14 41 21 20
    68 18 38 19
  
1000         
 61 13 56 31 30
    58 12 51 29
Positive Control Ethyl Methane Sulfonate 
500         
 29 21 711 808 856*
    27 20 724 905

Nonactivation Trial: 2 Experiment Call: Rejected
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 116 105 172 49 38
    109 106 132 40
    109 97 108 33
    91 92 83 31
Test Chemical N,N'-Dicyclohexylthiourea 
84         
 91 31 113 41 36
    97 30 73 25
    91 27 116 43
  
105         
 91 31 143 52 54
    80 23 166 70
    87 26 102 39
  
131         
 55 16 127 77 79*
    102 26 244 80
  
164         
 58 12 102 58 82*
    46 13 104 76
    35 6 115 111
Positive Control Ethyl Methane Sulfonate 
500         
 31 23 1234 1313 893*
    76 53 1298 569
    52 35 1246 796

Nonactivation Trial: 3 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 81 91 93 39 41
    110 104 143 43
    100 105 126 42
Test Chemical N,N'-Dicyclohexylthiourea 
62.9       
 66 21 119 61 54
    75 25 105 46
  
78.6       
 59 17 101 57 58
    63 20 141 74
    70 20 91 43
  
98.3       
 55 14 86 52 60
    62 18 108 58
    69 20 144 70
  
122.9       
 77 14 116 50 49
    81 21 131 54
    90 15 120 44
  
153.6       
 76 14 91 40 42
    74 16 109 49
    73 16 79 36
Positive Control Ethyl Methane Sulfonate 
500         
 58 37 1151 663 617*
    59 37 869 492
    57 38 1194 696

Non-Induced S9 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         
 85 106 106 41 43
    86 106 116 45
    82 92 98 40
    83 96 118 48
Test Chemical N,N'-Dicyclohexylthiourea 
52         
 90 116 155 58 54
    77 99 118 51
  
65         
 95 92 120 42 50
    82 83 141 58
  
82         
 76 39 165 73 81*
    63 32 171 90
  
102         
 67 25 281 140 148*
    68 25 320 156
  
128         
 56# 25 216 128 97*
    59 9 115 65
  
160         
 83 53 131 52 56
    76 45 135 60
  
200         
 71 42 116 55 53
    68 43 104 51
Positive Control 3-Methylcholanthrene 
5         
 57 58 400 233 215*
    77 68 430 187
    69 65 462 224

Non-Induced S9 Trial: 2 Experiment Call: Inconclusive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 136r 136 214 53 77
    119 106 285 80
    108 96 246 76
    99 97 224 75
Test Chemical N,N'-Dicyclohexylthiourea 
63         
 88 93 203 77 71
    96 112 188 65
  
79         
 80 64 195 82 72
    91 75 171 63
  
98         
 28 11 213 254
  
123         
 68 35 203 100
  
154         
 78 42 214 91 102
    61 32 207 113
  
192         
 71 38 183 86 92
    72 38 211 98
  
240         
 76 39 208 92 87
    79 37 196 83
  
300         
 88 45 243 92
    167r 40 159 32
Positive Control 3-Methylcholanthrene 
5         
 94 85 875 310 292*
    98 89 870 295
    116 98 938 271

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 Dimethyl Sulfoxide 
 0         
 102# 109 108 35 42
    93 91 136 49
Test Chemical N,N'-Dicyclohexylthiourea 
140         
 94 65 133 47 42
    96 60 107 37
  
233.3       
 81 44 93 38 38
    92 57 104 38
  
388.8       
 84 59 127 50 55
    79 50 142 60
  
648         
 71 50 119 56 46
    68 38 72 35
  
1080         
 83 54 145 58 50
    97 63 124 43
  
1800         
 89 42 128 48 60
    72 41 155 72
  
3000         
 86 42 123 48 44
    91 53 110 40
Positive Control 3-Methylcholanthrene 
5         
 64 33 335 175 215*
    41 17 311 255

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 Dimethyl Sulfoxide 
 0         
 100 85 249 83 65
    118 97 215 61
    108 91 211 65
    112 126 175 52
Test Chemical N,N'-Dicyclohexylthiourea 
52         
 96 84 213 74 67
    106 59 178 56
    91 71 195 72
  
66         
 83 33 196 79 77
    99 57 233 79
    81 48 178 74
  
82         
 91 41 201 74 82
    103 36 251 82
    79 42 212 90
  
102         
 90 39 219 81 86
    87 41 232 89
    88 42 236 89
  
128         
 95 43 235 83 78
    96 46 184 64
    90 39 235 87
  
160         
 85 40 234 92 78
    106# 87 181.5 57
    95 69 237 83
  
200         
 93 63 210 75 70
    108 89 213 66
    104 71 217 70
Positive Control 3-Methylcholanthrene 
5         
 86 71 554 214 224*
    84# 77 515 205
    85 66 644 254

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