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Study Information
Study Attribute Value
CEBS Accession Number: 002-02910-0002-0000-6
Chemical Name: Thiourea
CASRN: 62-56-6
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: G27458
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: Negative and Non-Toxic
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Water 
 0         
 97 107 49 17 22
    87 99 72 28
Test Chemical Thiourea 
313         
 76 101 60 26 24
    95 85 60 21
  
625         
 78 82 51 22 20
    78 80 41 18
  
1250         
 91 71 85 31 29
    86 80 71 28
  
2500         
 85 67 71 28 29
    90 72 81 30
  
5000         
 97 67 72 25 26
    89 77 75 28
Positive Control Ethyl Methane Sulfonate 
500         
 68 52 876 430 406*
    72 41 824 381
Negative Control Negative (Not Specified) 
 0         
 98 97 56 19 25*
    80 97 72 30

Nonactivation 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 Water 
 0         
 99 106 69 23 31
    91 111 86 32
    84 73 93 37
    102 110 99 32
Test Chemical Thiourea 
625         
 117 122 88 25
    131r 111 99 25
  
1250         
 105# 98 96 30 26
    114 94 73 21
  
2500         
 91 80 100 37
  
5000         
 84 69 78 31 36
    85 65 105 41
  
7500         
 87 61 108 41 39
    88 60 95 36
  
10000         
 88 69 143 54 47
    95 49 114 40
Positive Control Ethyl Methane Sulfonate 
500         
 49 28 1003 685 717*
    50 25 1114 750

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 Water 
 0         
 112 108 83 25 27
    100 98 75 25
    90 105 90 33
    75 89 56 25
Test Chemical Thiourea 
250         
 82 87 73 30 33
    86 92 93 36
  
500         
 91 94 85 31 33
    73 75 77 35
  
1000         
 81 83 76 31 29
    88 87 72 27
  
2000         
 79 76 58 24 27
    78 73 71 30
  
4000         
 88 73 102 39 40
    87 60 108 42
  
5000         
 74 57 82 37 36
    92 51 97 35
Positive Control Ethyl Methane Sulfonate 
500         
 44 22 871 665 757*
    34 19 772 757
    32 17 814 848

Induced S9 Trial: 1 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Water 
 0         
 81 90 183 75 81
    90 106 185 69
    101 110 236 78
    79 94 238 101
Test Chemical Thiourea 
500         
 81 76 272 113 145*
    65 61 344 177
  
1000         
 64 51 287 150 128*
    58 92 185 106
  
2000         
 71 71 280 132 135*
    57 70 237 138
  
4000         
 94 88 307 109 123
    84 87 347 137
  
6000         
 70 42 475 228 198*
    73 49 368 168
Positive Control 3-Methylcholanthrene 
5         
 36# 11 480 451 460*
    29 11 415 469

Induced S9 Trial: 2 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Water 
 0         
 89 102 125 47 52
    98 110 126 43
    77 98 132 57
    84 91 149 59
Test Chemical Thiourea 
250         
 88 68 213 81 75
    76 62 175 76
    87 59 174 67
  
500         
 71 39 250 117 101*
    72 47 254 118
    89 67 186 70
  
1000         
 64# 34 229.5 120 105*
    79 63 227 96
    85 70 253 99
  
2000         
 66 33 297 150 111*
    75 47 251 111
    87 124 184 70
  
4000         
 78# 42 246 105 110*
    65 45 228 118
    72 59 231 108
  
5000         
 69 22 281 137 115*
    74 32 248 112
    87 48 250 95
Positive Control 3-Methylcholanthrene 
5         
 42 13 361 289 310*
    39 9 389 332
    46 14 430 309

Induced S9 Trial: 3 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Water 
 0         
 93 111 105 38 34
    87 101 106 41
    87 89 57 22
    92 100 96 35
Test Chemical Thiourea 
250         
 81 80 86 35 35
    77 74 80 35
    87 68 88 34
  
500         
 79 83 70 29 31
    92 99 92 33
    125r 157 65 17
  
1000         
 95 89 113 40 33
    88 82 92 35
    77 78 54 23
  
2000         
 77 70 92 40 40
    92 72 120 44
    71 74 81 38
  
4000         
 88 67 122 46 44
    59 56 74 42
    70 63 96 46
  
5000         
 77 57 141 61 59*
    69 47 141 68
    88 70 128 49
Positive Control 3-Methylcholanthrene 
5         
 52 26 403 259 293*
    45 24 372 274
    44 23 453 347

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