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Study Information
Study Attribute Value
CEBS Accession Number: 002-02308-0003-0000-8
Chemical Name: Isobutyl nitrite
CASRN: 542-56-3
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 841266_SCE
Study Result: Positive

Study Result: Positive
Activation Trial Trial Call
No Activation  1  Positive 
Induced Rat Liver S9  1_S9  Weakly Positive 
Induced Rat Liver S9  2_S9  Positive 

Trial #: 1    Activation: No Activation    Date: 12/01/1982    Trial Call: Positive   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Dimethyl Sulfoxide 
0         
 50 1050 427 0.407 8.54 26.0 0.000
Test Chemical Isobutyl nitrite 
16         
 50 1043 446 0.428 8.92 26.0 5.151 
50         
 50 1051 520 0.495 10.40 26.0 21.664 
160         
 50 1048 597 0.570 11.94 26.0 40.079
Positive Control Mitomycin-C 
 0.005     
 25 526 740 1.407 29.60 26.0 245.945
Trend: 5.845        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 10/27/1982    Trial Call: Weakly Positive   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Dimethyl Sulfoxide 
0         
 50 1049 448 0.427 8.96 26.0 0.000
Test Chemical Isobutyl nitrite 
16         
 50 1050 484 0.461 9.68 26.0 7.933 
50         
 50 1051 510 0.485 10.20 26.0 13.623 
160         
 50 1047 599 0.572 11.98 26.0 33.961
Positive Control Cyclophosphamide 
1         
 50 1047 878 0.839 17.56 26.0 96.357
Trend: 4.773        
Probability: 0.000        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 01/19/1983    Trial Call: Positive   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Dimethyl Sulfoxide 
0         
 50 1048 475 0.453 9.50 26.0 0.000
Test Chemical Isobutyl nitrite 
150         
 50 1048 515 0.491 10.30 26.0 8.421 
200         
 50 1047 617 0.589 12.34 26.0 30.019 
250         
 50 1051 652 0.620 13.04 26.0 36.871
Positive Control Cyclophosphamide 
1         
 50 1046 888 0.849 17.76 26.0 87.305
Trend: 5.958        
Probability: 0.000