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Study Information
Study Attribute Value
CEBS Accession Number: 002-03010-0011-0000-8
Chemical Name: Xylenes (mixed)
CASRN: 1330-20-7
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 196823
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: Inconclusive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 95 104 84 30 23
    94 89 62 22
    97 97 65 22
    98 110 53 18
Test Chemical Xylenes (mixed) 
16         
 99 87 69 23 22
    98 82 60 20
  
24         
 95 87 57 20 21
    111 111 70 21
  
32         
 80 59 38 16 20
    71 84 51 24
  
40         
 72 56 53 24 29
    76 70 77 34
  
48         
 73 73 63 29 26
    65 70 44 23
Positive Control Methyl Methane Sulfonate 
15         
 57 32 244 144 164*
    47 42 261 184

Nonactivation 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         
 68 91 43 21 17
    82 108 41 17
    89 99 36 14
    73 102 36 17
Test Chemical Xylenes (mixed) 
45         
 80 83 45 19 18
    87 94 45 17
  
60         
 61 67 47 26 24
    61 34 40 22
  
75         
 80 53 71 30 35*
    55 46 67 40
  
90         
 81 38 53 22 25
    87 19 74 28
  
105         
 49 7 66 45 45*
    33 5 44 44
Positive Control Methyl Methane Sulfonate 
15         
 30 22 92 103 108*
    25 19 85 113

Nonactivation Trial: 3 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Dimethyl Sulfoxide 
 0         
 77 89 86 37 33
    94 86 98 35
    89 137 77 29
    91 89 79 29
Test Chemical Xylenes (mixed) 
45         
 83 98 85 34 32
    95 108 85 30
  
60         
 92 93 114 42 30
    87 105 48 18
  
75         
 93 75 84 30 27
    82 83 57 23
  
90         
 69 52 47 23 34
    64 39 86 45
  
105         
 59 15 142 80 88*
    67 11 191 95
Positive Control Methyl Methane Sulfonate 
15         
 39 35 162 138 132*
    35 29 130 126

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