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Study Information
Study Attribute Value
CEBS Accession Number: 002-02419-0014-0000-3
Chemical Name: Methoxychlor
CASRN: 72-43-5
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: G84704
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 Dimethyl Sulfoxide 
 0         
 115 111 106 31 33
    88 89 92 35
Test Chemical Methoxychlor 
11.3       
 88 89 87 33 36
    67 74 80 40
  
17.4       
 68 57 133 65 54
    85 82 109 43
  
26.8       
 83 72 99 40 45
    71 74 107 50
  
41.2       
 90 81 103 38 44
    78 79 116 50
  
63.4       
 79 43 147 62 54
    80 46 109 46
  
97.5       
 87 23 124 47 43
    89 22 105 39
  
150         
   
Positive Control Ethyl Methane Sulfonate 
500         
 34 26 716 695 681*
    35 29 696 666

Nonactivation Trial: 2 Experiment Call: No Call
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 111 96 115 34 38
    101 104 123 41
Test Chemical Methoxychlor 
44.5       
 104 71 115 37 29
    117 83 74 21
  
55.2       
 127r 65 83 22
    106 55 104 33
  
68.5       
 95 21 118 41 43
    91 21 121 44
  
84.9       
 56 6 114 67 66*
    59 6 114 65
  
105.3       
   
Positive Control Ethyl Methane Sulfonate 
500         
 702*
    52 26 1088 702

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         
 62 107 87 47 46
    153r 167 194 42
    58 88 69 40
    73 105 113 52
Test Chemical Methoxychlor 
19.7       
 93 93 126 45 53
    82 89 157 64
    82 100 125 51
  
26.3       
 84 83 114 45 48
    93 71 107 38
    93 40 170 61
  
35.2       
 99 85 120 40 42
    99 101 126 42
    82 92 105 43
  
47         
 86 98 99 38 41
    105 143 106 34
    84 96 125 50
  
62.8       
 94 95 115 41 56
    106 70 241 76
    69 71 108 52
  
83.9       
 89 47 139 52 58
    94 44 192 68
    91 49 142 52
  
112.1       
 90 12 324 120 82*
    85 19 166 65
    81 9 151 62
  
149.7       
   
   
Positive Control Ethyl Methane Sulfonate 
500         
 83 79 1045 421 630*
    34 36 847 839

Non-Induced S9 Trial: 1 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 85 82 109 43 46
    89 118 130 49
Test Chemical Methoxychlor 
12.8       
 77 64 164 71 64
    77 76 131 56
  
25.6       
 58 57 139 80 86*
    66 51 183 92
  
51.2       
 71 40 269 127 119*
    66 42 221 111
  
64         
 58 30 215 123 130*
    62 29 254 137
  
80         
 34 13 264 258 237*
    40 11 259 216
  
100         
  
125         
   
Positive Control 3-Methylcholanthrene 
6         
 66 49 399 201 203*
    80 56 494 205

Induced S9 Trial: 1 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 104 110 49 16 21
    86 90 66 26
Test Chemical Methoxychlor 
5.8       
 104 71 69 22 20
    83 70 44 18
  
9.7       
 104 110 55 18 18
    115 91 66 19
  
16.2       
 97 84 47 16
  
27         
 86 57 81 31 28
    88 54 65 25
  
45         
 83 34 67 27 37*
    77 34 110 48
  
75         
 49 13 72 49 46*
    41 10 53 43
  
125         
 29 4 45 52 59*
    24 3 48 67
Positive Control 3-Methylcholanthrene 
6         
 59 31 305 172 186*
    61 25 365 199

Induced S9 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         
 73 94 208 95 95
    82 106 235 96
Test Chemical Methoxychlor 
5.8       
 73 86 291 133 112
    93 109 253 91
  
9.7       
 86 85 316 122 134
    80 84 349 145
  
16.2       
 56 43 402 239 213*
    67 46 373 186
  
27         
 45 14 368 271 274*
    44 11 365 277
  
45         
 13 2 232 580 575*
    18 3 314 571
  
75         
   
Positive Control 3-Methylcholanthrene 
5         
 45 30 511 383 383*

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