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Study Information
Study Attribute Value
CEBS Accession Number: 002-02439-0001-0000-1
Chemical Name: Methyl isocyanate
CASRN: 624-83-9
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 933693_SCE
Study Result: Positive

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

Trial #: 1    Activation: No Activation    Date: 12/21/1984    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 1027 400 0.389 8.00 25.5 0.000
Test Chemical Methyl isocyanate 
 0.3       
 50 1030 417 0.405 8.34 25.5 3.946 
 0.9       
 50 1030 677 0.657 13.54 32.0 68.757 
3.1       
 50 1029 759 0.738 15.18 32.0 89.381 
9.2       
 0 0 0 0.000 0.00 32.0 N/A 
30.8       
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.001     
 50 1027 557 0.542 11.14 25.5 39.250
Mitomycin-C 
 0.01      
 5 105 209 1.990 41.80 25.5 411.055
Trend: 12.521        
Probability: 0.000        

Trial #: 2    Activation: No Activation    Date: 01/10/1985    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         
 25 513 217 0.423 8.68 25.5 0.000
Test Chemical Methyl isocyanate 
 0.7       
 25 513 238 0.464 9.52 25.5 9.677 
1.5       
 25 517 250 0.484 10.00 30.3 14.316 
3         
 25 521 302 0.580 12.08 30.3 37.034 
6         
 0 0 0 0.000 0.00 30.3 N/A
Positive Control Mitomycin-C 
 0.001     
 25 516 333 0.645 13.32 25.5 52.564
Mitomycin-C 
 0.01      
 5 105 186 1.771 37.20 25.5 318.776
Trend: 3.549        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 12/31/1984    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 1028 376 0.366 7.52 25.5 0.000
Test Chemical Methyl isocyanate 
 0.3       
 50 1031 406 0.394 8.12 25.5 7.665 
 0.9       
 50 1031 530 0.514 10.60 32.0 40.547 
3.1       
 50 1023 595 0.582 11.90 32.0 59.018 
9.2       
 0 0 0 0.000 0.00 32.0 N/A 
30.8       
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
 0.4       
 50 1035 587 0.567 11.74 25.5 55.061
Cyclophosphamide 
2         
 5 103 138 1.340 27.60 25.5 266.309
Trend: 8.064        
Probability: 0.000