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Study Information
Study Attribute Value
CEBS Accession Number: 002-01906-0008-0000-6
Chemical Name: Coumaphos
CASRN: 56-72-4
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 110131
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: Rejected
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Acetone 
 0         
 79 103 84 36 30
    77 100 80 35
    78 90 55 23
    71 108 58 27
Test Chemical Coumaphos 
5         
 105 92 110 35 43
    104 98 158 51
  
10         
 106 91 228 72 73*
    98 92 219 74
  
20         
 83 41 413 166 189*
    83 31 524 212
  
40         
 92 28 415 151 119*
    76 23 200 87
  
80         
 94 21 596 211 204*
    93 18 548 196
Positive Control Methyl Methane Sulfonate 
15         
 42 27 150 118 142*
    33 24 165 166

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 Acetone 
 0         
 67 110 93 46 44
    69 101 76 37
    77 92 77 33
    69 98 122 59
Test Chemical Coumaphos 
5         
 75 98 82 36 31
    76 98 60 26
  
10         
 80 103 81 34 33
    76 108 76 33
  
20         
 77 84 51 22 20
    80 88 41 17
  
30         
 71 61 69 32 27
    82# 87 55.5 23
  
40         
 67 68 69 34 39
    54 66 69 43
Positive Control Methyl Methane Sulfonate 
15         
 51 36 232 152 128*
    52 49 163 103

Nonactivation Trial: 3 Experiment Call: Negative
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Acetone 
 0         
 69 93 86 42 44
    68 81 98 48
    89 114 120 45
    91 112 108 39
Test Chemical Coumaphos 
2.5       
 118 95 145 41 38
    76 86 81 35
  
5         
 86 94 88 34 38
    97 81 119 41
  
10         
 109 71 91 28 37
    87 75 119 46
  
20         
 73 24 99 45 50
    68 28 112 55
Positive Control Methyl Methane Sulfonate 
15         
 52 30 294 189 199*
    44 30 277 208
Methyl Methane Sulfonate 
250         
 76 76 501 219 206*
    71 74 409 192

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 Acetone 
 0         
 89 102 59 22 28
    94 103 84 30
    82 97 67 27
    73 97 70 32
Test Chemical Coumaphos 
10         
 81 85 61 25 25
    90 84 64 24
  
12.5       
 80 73 64 27 26
    67 67 51 26
  
15         
 96 72 77 27 28
    75 62 66 29
  
20         
 90 65 71 26 28
    78 67 70 30
  
25         
 90 69 75 28 30
    74 46 70 32
Positive Control Methyl Methane Sulfonate 
15         
 26 19 97 124 119*
    41 23 140 114
Methyl Methane Sulfonate 
250         
 58 76 313 181 177*
    69 74 358 173

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 Acetone 
 0         
 86 96 41 16 21
    79 106 52 22
    78 103 48 21
    82 95 61 25
Test Chemical Coumaphos 
2.5       
 89 92 45 17 21
    94 94 71 25
  
5         
 91 89 111 41 39*
    77 79 84 36
  
10         
 86 83 65 25 26
    83 87 67 27
  
15         
 81 62 72 30 31
    77 69 75 33
  
20         
 87 52 71 27 29
    85 28 78 31
  
25         
   
Positive Control 3-Methylcholanthrene 
2.5       
 28 9 317 377 384*
    42 15 493 390

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 Acetone 
 0         
 100 99 90 30 26
    101 106 67 22
    100 105 68 23
    93 90 85 30
Test Chemical Coumaphos 
5         
 102 85 69 22 20
    117 89 61 17
  
10         
 85 73 109 43 35
    87 63 70 27
  
15         
 91 44 66 24 23
    88 79 59 22
  
20         
 85 67 90 36 30
    100 91 75 25
  
25         
 70 24 48 23 23
    90 21 62 23
Positive Control 3-Methylcholanthrene 
2.5       
 33 5 401 401 321*
    51 13 364 240

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