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Study Information
Study Attribute Value
CEBS Accession Number: 002-02845-0006-0000-7
Chemical Name: Styrene oxide
CASRN: 96-09-3
NTP Study Type: Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID: 692229
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: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Ethanol 
 0         
 92 95 68 25 19
    90 116 55 20
    95 94 35 12
    99 95 55 19
Test Chemical Styrene oxide 
10         
 109 50 174 53 68*
    85 49 224 88
    108 51 206 64
  
20         
 89 43 377 141 172*
    63 34 319 170
    66 35 407 205
  
30         
 54 22 504 310 357*
    44 18 483 366
    62# 27 727 394
  
40         
 78# 25 719 309 461*
    26 2 487 637
    51 10 668 438
  
50         
 51# 7 665 433 532*
    20 1 424 707
    36 4 494 455
  
60         
 15# 1 270 600 594*
    16r 1 327 703
    42 3 747 588
Positive Control Methyl Methane Sulfonate 
5         
 92 51 568 205 235*
    94 41 561 200
    63 32 568 300

Nonactivation Trial: 2 Experiment Call: Positive
  Conc.
ug/mL 		Cloning
Efficiency 		Relative Total
Growth 		Mutant Colonies Mutant Frequency Avg Mutant Frequency
Vehicle Control Ethanol 
 0         
 69 82 59 29 28
    94 97 81 29
    89 111 93 35
    87 109 54 21
Test Chemical Styrene oxide 
10         
 54 62 147 92 91*
    75 85 215 95
    72 55 187 87
  
20         
 44 34 418 314 334*
    54 29 541 335
    38 29 399 352
  
30         
 26 11 591 748 611*
    37 14 577 525
    38 12 639 561
  
40         
 36 10 617 574 758*
    26 6 712 913
    29 6 680 786
  
50         
 681*
    26 3 604 765
    29 4 528 597
  
60         
   
   
Positive Control Methyl Methane Sulfonate 
5         
 63 40 568 299 332*
    41 34 437 360
    40 19 403 337

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