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Study Information
Study Attribute Value
CEBS Accession Number: 002-02502-0009-0000-0
Chemical Name: N,N'-Dicyclohexylthiourea
CASRN: 1212-29-9
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: G18810
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 and Non-Toxic
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 78 114 98 42 38
    101 110 93 31
    79 92 87 37
    80 84 102 42
Test Chemical N,N'-Dicyclohexylthiourea 
62.5       
 79 44 116 49 41
    91 36 87 32
  
125         
 69 8 115 56 50
    75 17 99 44
  
250         
 78 6 100 43 42
    63# 5 79 42
  
500         
 34 2 54 54 60
    46 4 92 66
  
1000         
 47 4 77 54 55
    51 4 84 55
Positive Control Ethyl Methane Sulfonate 
500         
 38 29 846 739 647*
    67 49 1106 554

Nonactivation Trial: 2 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 87 92 55 21 17
    96 109 33 11
    81 94 38 16
    77 105 50 22
Test Chemical N,N'-Dicyclohexylthiourea 
31.3       
 53 19 26 16 14
    69 27 26 13
  
62.5       
 63 27 30 16 14
    81 30 30 12
  
125         
 65 16 23 12 14
    59 14 29 16
  
250         
 64 10 17 9 11
    64 13 27 14
  
500         
 51r 6 58 38
   
  
1000         
   
Positive Control Ethyl Methane Sulfonate 
500         
 16 9 302 629 540*
    17 9 234 450

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         
 105 101 71 23 22
    103 119 76 25
    92 92 55 20
    88 88 59 22
Test Chemical N,N'-Dicyclohexylthiourea 
15.6       
 99 61 38 13 12
    100 55 35 12
  
31.3       
 100 47 50 17 17
    98 34 48 16
  
62.5       
 64 14 41 21 20
    83 14 47 19
  
93.8       
 65 11 37 19 19
    75 14 42 19
  
125         
 56 6 84 50 48*
    68 9 94 46
  
187.5       
 36 3 63 58 60*
    39 3 71 61
Positive Control Ethyl Methane Sulfonate 
500         
 58 32 871 496 542*
    54 32 969 596
    59 31 944 535

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         
 115 125 47 14 25
    59 65 71 40
    85 110 55 22
Test Chemical N,N'-Dicyclohexylthiourea 
25         
 97 49 58 20 19
    96 90 55 19
  
50         
 59 19 54 31 26
    78 26 66 28
    82 62 45 18
  
100         
 65 9 69 35 30
    99 16 74 25
    84 12 75 30
  
125         
 83# 10 80 32 32
    42 3 31 25
    66 7 79 40
  
150         
 70# 10 72 34 28
    80 11 41 17
    84 11 79 31
  
187.5       
 77 8 76 33 30
    54 8 45 28
    71 8 60 28
Positive Control Ethyl Methane Sulfonate 
500         
 36 20 689 641 829*
    23 10 727 1054
    29 20 681 792

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         
 98 92 71 24 22
    92 98 59 21
    98 117 62 21
    86 93 54 21
Test Chemical N,N'-Dicyclohexylthiourea 
15.6       
 104 72 140 45 41*
    75 92 83 37
  
31.3       
 83 76 87 35 36*
    71 56 79 37
  
62.5       
 93 43 49 18 27
    78 39 87 37
  
93.8       
 106 39 70 22 34
    104 41 141 45
  
125         
 110 35 112 34 32
    103 24 91 30
  
187.5       
 78 17 93 40 35
    103 26 95 31
Positive Control 3-Methylcholanthrene 
7         
 88# 55 290 110 104*
    80 56 287 120
    87 63 212 82

Non-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         
 55 76 43 26 24
    78 97 61 26
    104 115 69 22
    78 112 50 21
Test Chemical N,N'-Dicyclohexylthiourea 
15.6       
 81 100 116 48 37*
    65 116 74 38
    58 89 46 26
  
31.3       
 77 89 71 31 31
    91 78 76 28
    67 79 66 33
  
62.5       
 79 73 69 29 31
    65 57 67 34
    88 76 77 29
  
93.8       
 65 55 71 37 34
    50 65 63 42
    91 66 60 22
  
125         
 104 40 97 31 31
    81 64 75 31
    104 73 95 31
  
187.5       
 106 81 73 23 29
    88 70 92 35
    82 46 71 29
Positive Control 3-Methylcholanthrene 
7         
 54 57 172 107 108*
    53 58 188 117
    60 51 181 101

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         
 74 91 115 52 47
    85# 104 109 43
    67 99 76 38
    74 106 120 54
Test Chemical N,N'-Dicyclohexylthiourea 
62.5       
 89 56 182 68 73*
    67 49 156 78
  
125         
 80 21 232 97 85*
    75 27 164 73
  
250         
 57 22 188 111 93*
    83 27 184 74
  
500         
 67 22 179 89 89*
    77 28 205 89
  
1000         
 71 29 154 72 72
    82 35 174 71
Positive Control 3-Methylcholanthrene 
5         
 50 26 589 395 389*
    50 27 577 383

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         
 66 113 93 47 53
    55 77 84 51
    71 95 157 74
    80 115 97 41
Test Chemical N,N'-Dicyclohexylthiourea 
50         
 69 65 152 73 68
    47 75 85 60
    89 77 191 72
  
75         
 64 84 97 50 59
    83 96 159 64
    71 66 134 63
  
100         
 79 59 158 67 64
    79 80 117 49
    94 59 211 75
  
150         
 73 53 139 63 67
    83 69 177 72
    89# 70 178.5 67
  
200         
 62 41 173 94 84*
    64 28 166 86
    73 29 158 72
  
250         
 51 39 76 50 63
    94 48 190 67
    97 50 207 72
Positive Control 3-Methylcholanthrene 
5         
 36 20 346 322 360*
    34 23 371 366
    24# 18 283.5 394

Induced S9 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         
 74 111 61 27 39
    94 98 108 38
    76 104 106 46
    69 88 92 45
Test Chemical N,N'-Dicyclohexylthiourea 
31.3       
 73 67 112 51 52
    68 54 106 52
  
62.5       
 82 46 79 32 34
    97 63 105 36
  
93.8       
 86 67 66 26 34
    67 56 86 43
  
125         
 76 56 86 38 38
    74 41 86 39
  
150         
 70 52 79 38 39
    66 47 80 41
  
187.5       
 100 47 139 46 47
    65 16 91 47
Positive Control 3-Methylcholanthrene 
5         
 70 66 530 252 252*
    72 48 517 240
    61 55 482 265

Induced S9 Trial: 4 Experiment Call: Equivocal
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 84# 82 130 52 53
    101 111 172 57
    87 104 140 54
    116 103 168 48
Test Chemical N,N'-Dicyclohexylthiourea 
31.3       
 51 32 114 75 85*
    64 33 193 101
    53 21 127 80
  
62.5       
 51 41 160 105 94*
    86 63 218 85
    91# 50 246 91
  
93.8       
 75# 29 222 99 90*
    74 32 193 87
    77 46 189 82
  
125         
 67 28 166 83 91*
    101 31 283 93
    63 23 180 95
  
150         
 70 41 146 70 69
    74# 34 154 69
  
187.5       
 70# 21 233 111 93*
    91 26 187 69
    74 22 223 100
Positive Control 3-Methylcholanthrene 
5         
 35 14 520 502 526*
    25 4 414 548
    29 6 460 529

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